DEVICE FOR THE IMPROVEMENT OF CARRYING A KAYAK › uploads › 8 › ...Device for Improvement of Carrying a Kayak Design Team Nick Herman, Nick Graham David Landerman, Mike Santry

DEVICE FOR THE IMPROVEMENT OF CARRYING A KAYAK

MEIE 4701/4702

Technical Design Report

December 5, 2017

Department of Mechanical and Industrial Engineering

College of Engineering, Northeastern University

Boston, MA 02115

Device for the Improvement of Carrying a Kayak

Fall 2017 Report

Design Advisor: Prof. Kowalski

Design Team Nick Graham, Nick Hermann

David Landerman, Mike Santry Jake Zimmerman

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Device for Improvement of Carrying a Kayak

Design Team

Nick Herman, Nick Graham David Landerman, Mike Santry

Jake Zimmerman

Design Advisor

Greg Kowalski

Abstract

Kayaking is a fun outdoor activity enjoyed by many, but the process one must go through to kayak can be grueling. Professor Kowalski, an avid kayaker, is looking for a more simplistic and efficient way to load and unload his kayak, as well as transport it to and from the loading dock. Professor Kowalski currently makes use of a set of attachable wheels, to roll his kayak to the loading dock and vice versa; this requires multiple trips and is very strenuous. By understanding the basic stress concentrators on the human body, as well as different methods of providing a mechanical advantage, the team looks to develop a wearable device/system that provides strength assistance in the transportation of a kayak. The concept in which the team will pursue consists of two systems. The first is a wearable upper body device to which the kayak will be secured at the hip, distributing the awkward load throughout the upper-body using a counterbalance on the opposite hip. The second system is a telescoping arm attached to the roof of the vehicle that will assist in the loading and unloading of the kayak by acting as a pivot point, reducing the kayaks weight by 50%. The team has developed the final working prototype and upon making final design improvements, is ready to enter the production phase.

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Table of Contents

1 Acknowledgments ................................................................................................................................. 8

2 Copyright .............................................................................................................................................. 8

3 Introduction ........................................................................................................................................... 9

4 Problem Statement .............................................................................................................................. 10

5 Background ......................................................................................................................................... 11

5.1 Physical Requirements ................................................................................................................ 11

5.2 Human Factors ............................................................................................................................ 11

5.3 Calculations & Theoretical Modeling ......................................................................................... 14

5.4 Patents ......................................................................................................................................... 14

5.4.1 Load and Torque Resistant Caliper Exoskeleton ................................................................ 15

5.4.2 Portable Load Lifting System ............................................................................................. 15

5.4.3 Adjustable, Iso-Elastic Support Apparatus ......................................................................... 16

5.4.4 Exoskeleton Arm Interface ................................................................................................. 17

5.5 Previously Published Work ......................................................................................................... 19

5.6 Existing Products ........................................................................................................................ 22

5.6.1 Removal from Roof of Car ................................................................................................. 22

5.6.2 Lower Body Support ........................................................................................................... 23

5.6.3 Lifting Assist ....................................................................................................................... 24

6 Preliminary Designs ............................................................................................................................ 26

6.1 Wheeled Jack .............................................................................................................................. 26

6.1.1 Advantages .......................................................................................................................... 27

6.1.2 Disadvantages ..................................................................................................................... 27

6.1.3 Thoughts for Moving Forward ............................................................................................ 27

6.2 Moment Arm Balancer ................................................................................................................ 27

6.2.1 Advantages .......................................................................................................................... 28

6.2.2 Disadvantages ..................................................................................................................... 28


6.3 Third Arm ................................................................................................................................... 29

6.3.1 Advantages .......................................................................................................................... 30

6.3.2 Disadvantages ..................................................................................................................... 31


6.4 Artificial Muscle ......................................................................................................................... 31

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6.4.1 Advantages .......................................................................................................................... 32

6.4.2 Disadvantages ..................................................................................................................... 33


7 Concept Decision ................................................................................................................................ 34

8 Design Review Process ....................................................................................................................... 35

8.1 Issues with Initial Design ............................................................................................................ 35

8.1.1 Degrees of Freedom in Exoskeleton Joints ......................................................................... 35

8.1.2 Development of Third Arm Subsystem .............................................................................. 35

8.1.3 Development Cost and Time Constraints ........................................................................... 36

8.2 Design Review ............................................................................................................................ 37

8.3 Post-Design Review Research .................................................................................................... 37

8.3.1 Carrying Harness for Surfboards and the Like ................................................................... 37

8.3.2 Canoe Carrier Backpack with Collapsible Table ................................................................ 38

8.3.3 Kayak Portage Harness and Method ................................................................................... 39

9 Final Design ........................................................................................................................................ 39

9.1 Pulley and Kayak Hook Subsystem ............................................................................................ 40

9.2 Procedure .................................................................................................................................... 41

9.3 Design Challenges ....................................................................................................................... 41

9.4 Potential Impact .......................................................................................................................... 42

10 Analysis & Testing .......................................................................................................................... 42

10.1 Moment Arm Analysis ................................................................................................................ 42

10.2 Frame Analysis ........................................................................................................................... 44

10.3 Frame 2D Analysis ...................................................................................................................... 45

10.4 Harness Testing ........................................................................................................................... 47

10.5 Frame Refinement ....................................................................................................................... 50

10.5.1 Geometric Compatibility ..................................................................................................... 50

10.5.2 Padding System ................................................................................................................... 50

10.5.3 Design for Manufacturability .............................................................................................. 51

10.5.4 Final Analysis ..................................................................................................................... 51

10.6 Telescoping Arm ......................................................................................................................... 57

10.7 Pulley Sub-system ....................................................................................................................... 62

11 Project Management ....................................................................................................................... 62

11.1 Future Improvements .................................................................................................................. 64

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11.2 Monitoring and Control .............................................................................................................. 64

11.3 SWOT Analysis .......................................................................................................................... 65

12 Conclusion ...................................................................................................................................... 65

13 Intellectual Property ........................................................................................................................ 66

13.1 Description of Problem ............................................................................................................... 66

13.2 Proof of Concept ......................................................................................................................... 66

13.3 Progress to Date .......................................................................................................................... 66

13.4 Individual Contributions ............................................................................................................. 66

13.5 Future Work ................................................................................................................................ 66

14 References ....................................................................................................................................... 67

15 Appendix A – Variables .................................................................................................................. 69

16 Appendix B – Human Factors Calculations .................................................................................... 71

17 Appendix C – Harness Calculations ............................................................................................... 73

18 Appendix D – Telescoping Arm Calculations ................................................................................ 83

19 Appendix E – Harness Testing SOP ............................................................................................... 85

19.1 Purpose ........................................................................................................................................ 86

19.2 Scope ........................................................................................................................................... 87

19.3 Pre-requisites ............................................................................................................................... 87

19.4 Responsibilities ........................................................................................................................... 88

19.5 Procedure .................................................................................................................................... 88

19.6 References ................................................................................................................................... 89

19.7 Definitions ................................................................................................................................... 89

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List of Figures

Figure 1: Wilderness Systems Tsunami 165 Kayak ..................................................................................... 9 Figure 2. Free Body Diagram of Current Kayak Lifting and Carrying Methods ....................................... 11 Figure 3: Human Factors Lifting Free Body Diagram [2] .......................................................................... 12 Figure 4: Typical Lifting Situation [1] ........................................................................................................ 13 Figure 5. Free Body Diagram of Current Kayak Lifting and Carrying Methods with Equations .............. 14 Figure 6. Patent Diagram of Full Body Exoskeleton [4] ............................................................................ 15 Figure 7. Powered Full Body Exoskeleton Patent Diagram [5] .................................................................. 16 Figure 8. Iso-Elastic Support Arm Patent Diagram [6] .............................................................................. 17 Figure 9. Passive Load Assist Arm Patent Diagram [7] ............................................................................. 18 Figure 10. Iso-Elastic Arm Free Body Diagram [8] ................................................................................... 19 Figure 11. Graph of Supporting Force v. Angle for Iso-Elastic Arm [8] ................................................... 20 Figure 12. Iso-Elastic Arm [8] .................................................................................................................... 20 Figure 13: Load Displacing Backpack [21] ................................................................................................ 21 Figure 14. Thule Hullavator [9] .................................................................................................................. 22 Figure 15. Thule Slipstream [10] ................................................................................................................ 23 Figure 16. Honda Walking Assist [11] ....................................................................................................... 23 Figure 17. Ski-Mojo [12] ............................................................................................................................ 24 Figure 18. Lowes Prototype Passive Exoskeleton [13] ............................................................................... 24 Figure 19. Lockheed Martin’s Human Universal Load Carrier (HULC) [14] ............................................ 25 Figure 20. The Lockheed Martin FORTIS Exoskeleton [15] ..................................................................... 25 Figure 21. Wheeled Jack Design ................................................................................................................. 26 Figure 22. Moment Arm Balancer Design .................................................................................................. 28 Figure 23. Third-Arm Design ..................................................................................................................... 30 Figure 24. Contraction of Nylon Fibers Under Varying Temperatures [16] .............................................. 32 Figure 25. Tensile Actuation v. Temperature for Nylon Fibers [16] .......................................................... 32 Figure 26: Iso-elastic Parallelogram ........................................................................................................... 36 Figure 27: Lockheed Martin FORTIS ......................................................................................................... 36 Figure 28: Carrying Harness for Surfboards [18] ....................................................................................... 38 Figure 29: Canoe Carrier Backpack [19] .................................................................................................... 38 Figure 30: Kayak Portage Harness [20] ...................................................................................................... 39 Figure 31: Pulley System ............................................................................................................................ 40 Figure 32: Hooking System ........................................................................................................................ 41 Figure 33: Combined free body diagram of Moment Arm Balancer (MAB) and the backpack ................ 42 Figure 34: List of Forces ............................................................................................................................. 43 Figure 35: MAB Free Body Diagram ......................................................................................................... 43 Figure 36: Frame Free Body Diagram ........................................................................................................ 44 Figure 37: Frame FBD 2, compatibility condition and strap force ............................................................. 44 Figure 38: 2-D Abaqus FEA of test frame (left) compared to initial frame design, stress and displacement ..................................................................................................................................................................... 46 Figure 39: ALPZ Outdoorz Commander Frame ......................................................................................... 47 Figure 40: Test Apparatus ........................................................................................................................... 47 Figure 41: Test with no counterweight ....................................................................................................... 48

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Figure 42: Test with 11-lb counterweight ................................................................................................... 49 Figure 43: 11-lb vs. 16-lb counterweight .................................................................................................... 49 Figure 44: Heavy Duty Hinge ..................................................................................................................... 50 Figure 45: Pipe Bend design to Notch/Weld design, shoulder flanges ....................................................... 51 Figure 46: Final Frame design with arms extended .................................................................................... 52 Figure 47: Final frame design with arms folded ......................................................................................... 52 Figure 48 ..................................................................................................................................................... 53 Figure 49: Final Moment Arm Balancer Free Body Diagrams .................................................................. 53 Figure 50 Final Frame Design Free Body Diagram .................................................................................... 54 Figure 51: Final Solidworks FEA Stress ..................................................................................................... 55 Figure 52 Final Solidworks Displacement .................................................................................................. 56 Figure 53 Final Solidworks Factor of Safety .............................................................................................. 57 Figure 54: Kayak supported at both sides with a centric load .................................................................... 58 Figure 55: Telescoping Arm Deflection ..................................................................................................... 59 Figure 56: Gantt Chart ................................................................................................................................ 63 Figure 57: Hinges and Cable Supports ....................................................................................................... 64 Figure 58. SWOT Analysis ......................................................................................................................... 65 Figure 59: User Wearing the Rigid Backpack ............................................................................................ 87 Figure 60: Test Apparatus ........................................................................................................................... 89

List of Tables

Table 1: Force Caused by Backpack [21] ................................................................................................... 21 Table 2: Percentage of Load Support by Back [21] .................................................................................... 22 Table 3: Design Matrix ............................................................................................................................... 34 Table 4: Material vs. Deflection ................................................................................................................. 60

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1 Acknowledgments

The team would like to thank Professor Kowalski for his feedback, support and guidance.

2 Copyright

“We the team members,

______________________________________________________________________________

Nick Graham Nick Hermann David Landerman Mike Santry Jake Zimmerman

______________________________________________________________________________

Greg Kowalski

Hereby assign our copyright of this report and of the corresponding Executive Summary to the Mechanical, and Industrial Engineering (MIE) Department of Northeastern University.” We also hereby agree that the video of our Oral Presentations is the full property of the MIE Department.

Publication of this report does not constitute approval by Northeastern University, the MIE Department or its faculty members of the findings or conclusions contained herein. It is published for the exchange and stimulation of ideas.

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3 Introduction

Sea kayaking, like running, is an aerobic exercise with a relatively low starting threshold for physical activity. However, several actions involved in getting the kayak to and from the water can be very challenging for some, and a significant limiting factor for others. Unlike other kinds of kayaks, sea kayaks have a relatively large chamber and length. Still-water kayaking requires the least amount of training, so it is the most often used by less avid kayakers. These people are less likely to possess the strength and or necessary equipment to easily accomplish the surrounding logistics of kayaking. The sponsor, Professor Kowalski, enjoys sea kayaking but has trouble with lifting the kayak on and off his car roof, as well as transporting the kayak to and from the water. Due to the location of the kayak on the vehicle, its height from the ground and the kayak’s rim distance from someone standing on the side of the vehicle, the action of getting the kayak on and off the car is quite awkward and the stress it puts on the lower back is significant. Additionally, after hours of paddling in the sun, the thought of carrying the kayak back to the car is dreadful. The team was tasked with building a device to assist Professor Kowalski, and those like him, in getting their kayaks on and off their cars as well as to and from the water. The specific kayak model in question is a Tsunami 165, made by Wilderness Systems and can be seen in Figure 1.

Figure 1: Wilderness Systems Tsunami 165 Kayak

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4 Problem Statement

The original assignment called for the development of an exoskeleton system, built to enhance the user’s upper body strength. To better understand the problem and the criteria for success, the team decided to examine the situation and craft a refined problem statement. The team must design for a kayak, approximately 45-60 pounds and 16.5 feet long, to be put atop and brought down from a car, approximately 5-6 feet high, and to be carried approximately 50 yards each way, to and from the water. Currently Professor Kowalski uses a set of wheels, which he affixes to the kayak, to roll the kayak between his car and the ocean. The wheels cannot be stowed inside the kayak nor can they be on the kayak when atop the vehicle, and thus, must be stowed in the car when not being used for their narrow purpose. One of the key design requirements was to save time, and the clearest way to do this was to make sure whatever device is used must be portable enough to fit inside the kayak. This would eliminate the need to make redundant trips to the car. The products currently on the market are not only overpriced but only accomplish parts of this process. Another goal of the product is to assist with lifting/lowering as well as carrying. With all this in mind, the final problem statement was, “Develop a portable device to assist in the transportation of a sea kayak, including lifting it on and off a car roof, as well as carrying it to and from the water, in a time efficient and cost-effective manner.”

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5 Background

5.1 Physical Requirements

The act of unloading a kayak from atop the car and carrying it to the water has the potential to cause excessive strain on the joints and back of the user. These actions were broken down and examined with the help of free body diagrams to identify the key points of strain. The diagrams, seen in Figure 2, show the user as the kayak is being raised or lowered (a) and while it is being carried on the shoulder (b).

Figure 2. Free Body Diagram of Current Kayak Lifting and Carrying Methods

When lowering the kayak to the water or picking it up from the water, the full weight of the kayak is supported by the user’s arms, causing additional forces at the lower back, shoulders, and arms. These areas along with the knees, are all areas of concern that should be addressed. When the kayak is carried on the user’s shoulder, the forces experienced are distributed through the shoulder closer to the center of gravity. However, this also shifts the user’s center of gravity upwards which could increase the risk of falling.

5.2 Human Factors

There are several human factor requirements to consider for this project including strength, flexibility, and body dimensions. Specifically, this section focuses on the stress induced in the lower back while lifting an

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object from the ground, as well as the reactionary forces through the arm. The lower back is of interest because it is considered the least durable link of the musculoskeletal system, and thus experiences the highest rate of injury [1]. As a rough estimate, when lifting an object from the ground, the lower back will experience 8 times the weight of the object plus 4 times the weight of the lifter’s torso. The forces and moments that cause the high load on the lower back are shown in Figure 3, below. For example, a lower back with a 120-pound torso, lifting a 50-pound kayak, will experience 880 pounds of force. This amount of force coupled with poor lifting form can easily cause injury to the L5/S1 lumbosacral disc. For a human to safely lift an object from the position seen in Figure 3, the moment created by the back-muscle must be greater than the moment created by the weight of load combined with the weight of a person’s torso. [2] With this calculation, the force the back-muscle must provide can be calculated; this is a great starting point for the project. Full calculations for muscular and compression forces as well as moment through the L5/S1 disc can be found in Appendix A.

Figure 3: Human Factors Lifting Free Body Diagram [2]

The team also decided to look at a typical carrying situation, with a person carrying a load in front of their body, with their two arms. Using Figure 4 on the following page, and adapting it to the group’s needs, the

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reactionary forces through the elbow and shoulder could be found. The full calculations for this can be found in Appendix A as well.

Figure 4: Typical Lifting Situation [1]

In a study funded by DARPA it was found that during analysis of soldiers walking with loads, the larger the load, the more their form changes. Specifically, the angle of their knee and the timing, position, and flexing of the ankle. This might be good to keep in mind when designing the lower body exoskeleton; possible remedies might include spring reinforcements on the knee and ankle [3].

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5.3 Calculations & Theoretical Modeling

Shown in Figure 5, are two free body diagrams depicting the non-assisted methods for lifting a kayak.

Figure 5. Free Body Diagram of Current Kayak Lifting and Carrying Methods with Equations

The first clearly shows a significant risk to the lower back, given the large distances between the centers of gravity. The second shows a person carrying a kayak over their shoulder. This approach is very top-heavy, leaving the kayaker vulnerable to slipping and falling, which is likely in low tide when walking out to the water. This phenomenon occurs when an angle is applied to the forces, i.e. the person is leaning slightly, making the perpendicular distance between the centers of gravity larger, causing a stronger moment. Furthermore, there is potential to damage the shoulder as well as the neck which is connected to the spinal cord and can make for some debilitating injuries.

5.4 Patents

A patent search was performed using the USPTO search tool and using the relevant classification schema for the proposed designs. These patents were granted to devices related to the use of exoskeletons designed to support and assist in carrying a load. The patented designs were all found to be distinct from the design proposed despite performing similar functions.

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5.4.1 Load and Torque Resistant Caliper Exoskeleton

This patent details an exoskeleton assembly with an upper body and lower body portion connected with a pivoting joint. This device is detailed as having a caliper assembly connected to both the upper and lower body portions. This assembly, as seen in Figure 6, includes a load arm supported with a strut and pistons. These pistons provide an upright position for a mounting component on the load arm. This patent portrays a method of mounting and maintaining a load in front of the user’s body; this may be useful in considering how best to handle such a load with an unpowered exoskeleton [4].

Figure 6. Patent Diagram of Full Body Exoskeleton [4]

5.4.2 Portable Load Lifting System

This patent describes a portable load lifting system consisting of a powered exoskeleton, with a backpack mounted lifting mechanism and a lower body support system, shown in Figure 7. The lifting mechanism is operated by using a moveable, over-the-shoulder lifting mechanism with lifting straps connected to a winch. These straps would be connected to a load and lifted in front of the user. This patent is related to the Lockheed Martin HULC exoskeleton, and details certain methods of its use. This design is another method of handling a load, although this positioning and load handling mechanism is not suitable for kayak carrying, it could provide inspiration for how to safely distribute the load [5].

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Figure 7. Powered Full Body Exoskeleton Patent Diagram [5]

5.4.3 Adjustable, Iso-Elastic Support Apparatus

This patent details a support for a camera utilizing an adjustable, iso-elastic support arm, shown in Figure 8. This is related to the Steadicam line of products and may be in use in their product line. This arm would be attached to a harness with tension in the springs to be continuously adjustable throughout operation so that the resting height of the mount can be raised or lowered. Another key feature of this iso-elastic design is that movement on one end of the arm will occur independently from the other arm, allowing for the stability desired in camera shots. This patent provides some insight into how an iso-elastic arm can be modified and adapted to support a considerable load [6].

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Figure 8. Iso-Elastic Support Arm Patent Diagram [6]

5.4.4 Exoskeleton Arm Interface

This design, seen in Figure 9, details a back-mounted pivot connection to which a load-assist arm would be mounted. The assembly is mounted on a rigid backpack that connects to the lower body exoskeleton in order to support the load. The load-assist arm is mounted at this pivot with a series of weights to balance its load and allow for ease of operation. This is another method of supporting a load through an arm, possibly iso-elastic, and should provide more inspiration for managing loads [7].

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Figure 9. Passive Load Assist Arm Patent Diagram [7]

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5.5 Previously Published Work

Ruprecht Altenburger, et al, describes a mechanical mechanism for which the lifting force remains relatively constant throughout its range of motion, in Robomech Journal. The intent of this device is to provide 7.5kg of lifting support, using only spring forces in a wearable exoskeleton. The basis of this design centers around iso-elasticity where a parallelogram is constructed with a spring connected between points A and B in order to compensate for gravity. A free body diagram of this concept is shown in Figure 10.

Figure 10. Iso-Elastic Arm Free Body Diagram [8]

In this case, the lifting force would be

𝑭𝒃 =𝒃𝒄𝑭𝒔𝒑𝒓𝒊𝒏𝒈 =

𝒃𝒄𝒌𝒄 = 𝒌𝒃 Equation 1

Where Fb is the lifting force, a, b, and c are the geometric lengths, and k is the spring constant. This means the lifting force is independent to the length of the spring c and the angle ϕ. Furthermore, no external torque or force is required to balance the weight in any orientation for the predefined load force Fz, a characteristic referred to as iso-elasticity. During this process, a modified parallelogram was designed and constructed in order to improve the characteristics of the design. The result is a parallelogram with a four-bar linkage so that the position of A causes the spring to exert greater forces when the parallelogram is extended upwards and less force while lowered. Figure 11 shows the supporting force Fz versus the angle ϕ both before (left) and after optimization (right).

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Figure 11. Graph of Supporting Force v. Angle for Iso-Elastic Arm [8]

Having performed desirably, the modified parallelogram was then mounted to another parallelogram and the entire assembly mounted to a carrying system at chest level. This assembly is then strapped to the user’s forearm, offering the 7.5 kg of load assistance as designed [8]. This setup can be seen below in Figure 12.

Figure 12. Iso-Elastic Arm [8]

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M. Lafiandra, et al, examines the forces encountered whilst using a backpack type load carrying system in Medicine & Science in Sports and Exercise. Using a military issue lightweight backpack, shown in Figure 13, with an externally mounted frame, the study mounted force transducers to examine the forces experienced while using a backpack with two contact points. [21]

Figure 13: Load Displacing Backpack [21]

The subjects in the study were fitted with backpacks with three mass conditions (13.6kg, 27.2kg, and 40.8kg) all with an identical center of mass (COM). The subjects then walked on a level treadmill at 1.34 m/s for approximately 3 minutes for each weight condition. Table 1 displays the mean maximum and minimum forces experienced by the subjects at each force transducer location. [21]

Table 1: Force Caused by Backpack [21]

This data was then used to determine the percentages of the loads supported by areas of the back. This data is displayed in Table 2 for each mass condition.

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Table 2: Percentage of Load Support by Back [21]

This shows that approximately 30% of the weight can be transferred to the lower back with the use of the hip level belt. Using a novel approach for measuring the forces experiences by the subjects allowed for the study to determine the areas where the forces experienced are greatest and the way this popular type of backpack distributes weight.

5.6 Existing Products

5.6.1 Removal from Roof of Car

There are a few approaches to get the kayak from the top of vehicle, to the user’s reach, so that it can then be carried. The powered assist devices are the Thule Hullavator, shown in Figure 14 and the Yakima Showdown which both use air struts to place the kayak within reach and then replace it safely on the car. These products cost around $600 and do nothing to assist the user with the walk to the water [9].

Figure 14. Thule Hullavator [9]

The Thule Slipstream, shown in Figure 15, offers an extended rear loading guide so the user can lift it straight onto the car’s roof with reduced effort, as the kayak is supported by the rack for most of the process. This device is less expensive than other products, but it offers no actual assistance in lifting the kayak [10].

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Figure 15. Thule Slipstream [10]

5.6.2 Lower Body Support

The Honda Walking Assist, seen in Figure 16, is a device currently being leased for use in rehabilitation centers, to assist in learning to walk. To move, a computer uses a hip angle sensor to activate a motor and improve the symmetry of the timing of the leg lifting. Weighing 2.7kg and with a battery life of 60 minutes, the device is appropriate for helping the user train to walk again, but does not carry a significant load [11].

Figure 16. Honda Walking Assist [11]

The Ski-mojo, shown in Figure 17, is a passive device that clips into the user’s ski boots and straps to the outside of the legs to assist in leg extension. These devices are intended to reduce the impact on the legs and reduce muscle fatigue. The use of this device requires the user be wearing ski boots, so they are limited outside of that scope [12].

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Figure 17. Ski-Mojo [12]

5.6.3 Lifting Assist

The Lowes Prototype exoskeleton, seen in Figure 18, is intended to assist in the lifting of objects and provides support as they are placed back down, a task common in retailers such as Lowes. This is done through the bending of carbon fiber rods behind the back that are strapped to the user at the shoulder, waist, and thigh. This device promotes proper lifting form as it assists with lifting to reduce the possibility of injury however it does not offer any assistance while walking around [13].

Figure 18. Lowes Prototype Passive Exoskeleton [13]

Lockheed Martin’s Human Universal Load Carrier (HULC) is a powered exoskeleton designed for use in combat situations to assist the user in carrying loads and reducing the oxygen required as the user completes tasks. The device, shown in Figure 19, can support a load of up to 200lbs and travel up to 20km on level terrain. Without power, the exoskeleton will continue to support a load while not hindering the user’s mobility. This device is a very advanced powered exoskeleton made through military contracts so even if it were available, the price would be exorbitantly high [14].

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Figure 19. Lockheed Martin’s Human Universal Load Carrier (HULC) [14]

The Lockheed Martin FORTIS exoskeleton is an unpowered variant of the HULC exoskeleton adapted for use in industrial applications. This device is lightweight and allows a tool of up to 36lbs to be moved freely and without any effort around the user. At $20,000, the system is still unaffordable but offers a lightweight solution to managing a load [15]. This exoskeleton can be seen below, in Figure 20.

Figure 20. The Lockheed Martin FORTIS Exoskeleton [15]

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6 Preliminary Designs

During the brainstorming phase, the team came up with several interesting and innovative concepts to accomplish the design goals. The major goal of the project is load management; how to get the load to be in a less awkward place to prevent injury and once it is there, to assist with providing the necessary force to lift the kayak. This section will focus on the four main preliminary designs to solve the problem.

6.1 Wheeled Jack

This design utilizes a cart with wheels and a jack to assist the user with lifting and transporting the kayak. In the fully extended position the jack would allow the user to slide the kayak from the car roof and strap it onto the wheeled cart. The jack would then be lowered to increase the ease of transportation to the body of water. Once rolled to the body of water, the kayak would be taken off the cart, at which point wheels would be folded into the cart to allow the entire assembly to slide into the kayak’s storage compartment. At the end of the day, this process would be repeated in reverse to get the kayak from the body of water to the roof of the car. This concept is flexible in that it leaves several options to provide the lifting force. A few options that the team considered were hydraulics, pneumatics, and a mechanical ratchet. However, these options are not ideal, as they complicate the system. A schematic of the Wheeled Jack can be seen in Figure 21.

Figure 21. Wheeled Jack Design

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6.1.1 Advantages

The main advantage of the wheeled jack is its simplicity. The design attempts to solve the problem statement in a very straightforward way. This simplicity allows for the design of a durable, low cost system that does not require any complex or expensive components. As mentioned above, another key advantage to this concept is the lift’s design flexibility. This flexibility will provide the team with more options to solve design challenges over the course of the project. Having several options will allow the team to the weigh cost and utility of each component and end up with the most functional, low cost final product.

6.1.2 Disadvantages

The main disadvantages of this concept center on the ability to fit it into the storage compartment of the kayak. The concept would likely be on the heavy end, unless high-strength materials such as carbon fiber or titanium were used to reduce the overall weight of the device. These materials are expensive and if used would make it more difficult for the team to keep the total cost of the device down. Additionally, it is possible that if the cart were too heavy, it could alter the buoyancy and balance of the kayak in the water. Along the same line, keeping the size of the concept small enough to fit into the kayak’s storage compartment would be a major engineering challenge. Since the device would need to extend up to the height of a car roof, it will naturally have to be somewhat large. One way around this is designing it to be foldable, which will increase complexity and cost.

6.1.3 Thoughts for Moving Forward

The simplicity and flexibility of this design concept are desirable, but they do not negate all of the disadvantages. The team will continue to pursue options and ideas to reduce size and weight of this device to increase its feasibility.

6.2 Moment Arm Balancer

This idea has three main aspects: moment management, load assistance and vehicle interface. When carrying a kayak over a distance, it is most convenient, due to space limitations, to carry the boat’s length in parallel to one’s path on one side of the body at either hip or shoulder level. This creates a distance between the kayak’s center of gravity and the kayaker’s center of gravity, thus applying a moment which wrenches the back to the left or right. The Moment Arm Balancer sought to first solve this problem by balancing the kayak, being hooked in to some sort of harness at hip level on one side, with a variable length arm on the opposite side which holds up a fixed weight. This idea is depicted below in the free body diagram.

The second aspect centered on how to deal with the force once it is balanced at the center of gravity. A lower body passive exoskeleton will distribute the force from the waist to the ground. The methods involved in this process are still being determined.

The third aspect of this idea is a roof-rack on top of the vehicle which would assist with getting the kayak up/down from the roof. This rack would mimic the Thule Hullavator Pro which had two hooks coming down the side of the car on a rail system; the main difference being that the Thule rack is run by air springs [6]. This design would be mechanical using a belt system along with a ratchet mechanism. There would

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also be an arm which folded into an inconspicuous location on the rack but when extended, would provide a significant mechanical advantage. This would highly reduce the amount of force the user would need to lift the kayak onto the car. While the kayak is being slid up the side of the car, it would be supported by pads as not to scratch the car. When being let down, the tension in the belt would be released, at which point, a rotational damper would ease the speed of descent, as not to damage the rack, the vehicle, or the kayak. In the side view shown in Figure 22, the bars shown are meant to run along the user’s legs, with foot pads to step into.

Figure 22. Moment Arm Balancer Design

6.2.1 Advantages

This device has several major advantages. For starters, the concept is intuitive. It is reminiscent of a shoulder yoke, which people used to carry buckets by balancing them on both shoulders. It is also hands free, and, considering all the team’s designs require a lower body passive exoskeleton, the remainder of the components that go on the user are comparatively light. This design is portable and unpowered, ergo splash resistant. Also, the roof rack’s control has a simple up and down motion of a long lever arm, resembling a breaker bar, providing unpowered assistance to the user.

6.2.2 Disadvantages

To maintain cost affectability and universality of adaptation with different cars, the concept of having a separate semi-complex roof rack assembly is not ideal. Professor Kowalski, and others in his position, may not have roof racks. Additionally, if they were presented with the opportunity for one, they would want it to be easily removable for convenience and practicality when it is not being used. Any roof rack which has

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enough stability to stay on while the car is in motion has to be affixed firmly, and as a result, will be hard to put on or take off.


Moving forward with this concept, there is an idea for this fixed weight to be the kayaker’s gear bag. This is a secondary goal, to be tackled after the team can prove the concept works. This would minimize the additional weight which would have to be carried since the kayaker needs to bring the gear bag to and from the water anyways. An augmentation to this idea would be to have small weights in case the weight of the gear bag is not heavy enough to properly balance the moments. Finally, this project still leaves the team with the difficult task of designing a lower body exoskeleton.

6.3 Third Arm

This design makes use of a mechanical arm, extruding from a wearable back brace, with the function of gripping and moving a kayak in a simple and controllable manner. This “third arm” would be controlled with a T-bar on the arm itself, located in front of the user for maximum control. The user first will put on the Third Arm and its accompanying back-brace along with a lower-body device worn on the legs. Then, the user will move the Third Arm up to kayak height and grab the kayak using an adjustable hook-grip. Once the kayak has been secured with the Third Arm, it is then lowered to waist height using the T-bar positioned in front of the user. Once the kayak is at waist height, the Third Arm will then swivel the kayak to the side of the user instead of in front of him; this is done for ease of transport, as it would be quite awkward to carry a 16.5-foot kayak in front of a person’s body. There is a plan in place for allowing the user to also carry the kayak at shoulder height if desirable. After the kayak has been swiveled to the side of the user, at hip height, the user can begin transporting the kayak to the loading dock. Upon arrival at the loading dock, the user then lowers the third arm to the ground and releases the kayak. After this step is complete, the user takes off the Third Arm as well as the lower body device if they wish and folds them up into the approximate size of a gear bag. The lower body device can be worn while kayaking if the user does not desire to take it off. The aim is to make this concept a passive one, to avoid significant power usage and maintain water resistance. The mechanical advantage provided by the arm will come from a spring/dampening system or elastic bands in tension to provide partial strength assistance in a safe and controllable manner. A simple sketch of the concept is shown in Figure 23, with allowable rotation at the hip.

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Figure 23. Third-Arm Design

6.3.1 Advantages

This design has a many strong suits to it, making it a desirable concept to move forward with. First, the device is very maneuverable. Using a three-bar linkage combined with the swiveling action at the hips, a kayak can be lifted from just about anywhere, and positioned in the most comfortable position for the user, whether that be an over-the-shoulder carry or a hip carry. Second, the three-bar linkage will also be very easy to fold up into a desirable size to be fit in the kayak. Third, due to the passive nature of this device, splash resistance is not a factor, which in turn, allows the team to keep the price point of the device down due to the lack of a power source and no water resistance considerations. Furthermore, with the adjustable hook, this device could be adapted to at-home use, carrying any device graspable by the hook. Lastly, with the method of spring/dampeners or elastic bands in tension, weights greater than 45-60 pounds could theoretically be lifted, with minimum strength input from the user.

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6.3.2 Disadvantages

Although this is a favorable design concept, there are a few disadvantages with it. The first disadvantage is bulkiness of this device. Although it will be able to fold up relatively easily, the device itself still has the potential of being very cumbersome. This is an issue because the device must fit in the kayak and cannot affect the buoyancy of the water-craft. Second, the swiveling action of the kayak from the front of the user to the user’s hip requires a significant amount of space. This kayak is going to be 16.5 feet long, requiring a very large turn radius to move from parallel to the human body, to a perpendicular position at the user’s hip. This is something that must be considered because quite often, the user’s car is not the only car at the loading facility for these kayaks. The user would have to either park their car 6-10 feet away from an adjacent car, or walk with the kayak in a very awkward position, until enough space has been obtained to allow for the swivel action to take place. Lastly, the back brace to which the Third Arm is attached would have to be very beefy, while still allowing the swivel motion. This back brace must displace the force on the arm due to the kayak through the back, to the legs. If this is not done properly, the user’s lower back would be taking the brunt of the force from the kayak, even though the arm is holding the kayak.


The advantages of this design concept make it a very promising concept moving forward. The disadvantages are something that should be noted, but are all solvable issues. However, there are two main concerns of this concept. The first concern is the force displacement issue mentioned above; the force created from the kayak must be displaced through the back and to the user’s legs, in a safe and simple manner. The second concern is the force displacement issue once the first concern is solved. Once the force is displaced to the legs, it must then be displaced through the legs, to the floor, using a lower body device that does not hinder walking.

6.4 Artificial Muscle

A concept was discussed involving the use of artificial muscles to provide strength assistance, or possibly combing an array of artificial muscles with one of the traditional exoskeleton concepts. Artificial muscle fibers are created by weaving nylon fiber, fishing wire or sewing thread, into extremely tight and complex patterns. These patterns are then heated or cooled to provide tension or compression which can be converted into strength assistance. With extreme twisting, coiled muscles “can contract by 49%, lift loads over 100 times heavier than can human muscle of the same length and weight, and generate 5.3 kilowatts of mechanical work per kilogram of muscle weight, similar to that produced by a jet engine [16].” Upon researching this relatively new field, there was initial excitement due to significant loads these artificial muscles could handle. To adapt these artificial muscles to the problem statement, it was decided that the woven pattern must be wearable by the user. There would then be a heating/cooling element on the backside of the fibers, covering the tricep area of the human arm, lower back and hamstring/glute area. Applying pressure on this element during the initial stages of lifting, would activate the heating element, heating the artificial muscle, providing compression, which would then provide the desired strength assistance. Once

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the pressures on the element are alleviated when the lifting action ceases, the cooling portion of the element activates, reducing the compression and returning the artificial muscles to the initial configuration. Theoretical concept design, advantages and disadvantages of this concept, as well as some data regarding tensile actuation and amount of heating provided are shown in Figures 24 and 25.

Figure 24. Contraction of Nylon Fibers Under Varying Temperatures [16]

Figure 25. Tensile Actuation v. Temperature for Nylon Fibers [16]

6.4.1 Advantages

The advantages of this design were immediately recognizable which is why this concept was included, even though it is new technology that is still being pioneered today. Initially, an array of artificial muscles has

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the potential to be extremely wearable and lightweight. They are also completely water resistant and could potentially be worn the entire time while kayaking, with just the heating and cooling elements in mind when considering water resistance. Furthermore, as mentioned above, these artificial muscles have the potential of lifting loads 100 times heavy than human muscles comparable in size. This is more than enough strength assistance and could provide total strength assistance as opposed to partial assistance, still requiring some user input. Finally, like the Third Arm, these artificial muscles could be adapted to at-home use, simply worn while executing normal chores around the house.

6.4.2 Disadvantages

Although this concept would be a revolutionary solution to the problem statement, there are a few major disadvantages that render this concept unfeasible for the easy, convenient transport of a kayak. The first disadvantage is highlighted in the graph above. Although these woven fibers can produce a significant amount tensile strength, a considerable amount of heating is required to produce this strength. For the scenario of carrying a 45-60-pound kayak, the heating element would need to reach a minimum of 100 ℃ (about 20% tensile actuation) to lift the weight. This is a concern because if the user is wearing this array of artificial muscles with nothing to guard his/her skin, serious burns can occur. To better understand how this concept could be adapted to the problem at hand, the group reached out to Carter Haines of the University of Texas at Dallas. [16] The group was informed that this heating would actually need to occur over 10’s of seconds to provide the desire strength assistance. This is not feasible for the task at hand because one of the main design requirements is “ease of use” and “time efficiency.” Additionally, an enormous amount of material would be required, driving up cost and further complicating the already complex process of weaving these fibers into a pattern which produces predictable tension and compression.


Taking into consideration everything discussed above, the team has decided to not move further with this concept. Although this would be an incredibly inventive way of solving the problem, it simply is not the best route to take regarding efficiency and ease of use.

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7 Concept Decision

To determine which concept to move forward with, the team made use of a design matrix to weigh each concept against the critical design requirements. This design matrix is shown in Table 3.

Table 3: Design Matrix

When crafting this design matrix, the team had to keep the main design requirements in mind. The top section of the matrix is used to determine which of the main design requirements are the most important. After comparing all design requirements, it was determined that time efficiency and water resistance were the two most important requirements. Water resistance was determined to be the most critical design requirement because the device must be able to withstand any water that could potentially find its way into the kayak; if the device breaks while kayaking, the user will not only have to transport the kayak on their own but the broken device itself. This is a major concern because every kayak user experiences some amount of fatigue after rowing, so the transportation of the kayak after the activity becomes an even more grueling task with an increased potential for injury.

With this is mind, the team then compared the four potential concepts as to how well they fulfilled the design requirements. The clear winner was the Moment Arm Balance due to its superior water resistance and lack of power usage. The reason this concept is the most water resistant out of the four presented is due to the fact that it will be completely passive; with no power supply to worry about, water resistance becomes a simple task. Although the Wheeled Jack was the most time efficient of the four concepts, it was determined that this did not fully answer the problem statement. Furthermore, the Wheeled Jack concept was very similar to the original scenario in which the team is improving upon. Although the Wheeled Jack assists the user in loading and unloading the kayak from the vehicle, the user is still dragging the kayak with the help of wheels. The team realized during these discussions that some combination of concepts was necessary to fully fulfil the problem statement.

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8 Design Review Process

8.1 Issues with Initial Design

Leading up to the design review, the team began to run into major issues with the final design concept chosen at the end of August. The first iteration design concept was previously discussed in greater detail in Section 7 of this report. These issues fell into three major categories, which will be detailed in the subsections below. The first challenge was how many degrees of freedom were required to design a comfortable exoskeleton that allows the user to walk with a normal gait. The second issue revolved around the complex geometry required for the “Third Arm” subsystem to operate properly. Finally, the last issue stemmed from the significant development cost and time associated with similar products already on the market.

8.1.1 Degrees of Freedom in Exoskeleton Joints

For an exoskeleton to allow a user to move freely and be comfortable, it must replicate the degrees of freedom (DOFs) in the human joint it seeks to enhance. For example, since the human hip is a ball and socket joint, it has three DOFs; flexion/extension, abduction/adduction, and internal/external rotation [17]. Similarly, the ankle has three DOFs and the knee has two DOFs. When the hip, knee, and ankle joints are combined into a single system it creates a very complex system. This high order system is very difficult to control with motors and hydraulic actuators, and becomes even more difficult to control if passive systems are used. To ensure such a system would work properly, a very high-level understanding of systems and control is required. In addition, this complexity requires a large amount of development time, which is much longer than the duration of this capstone project.

8.1.2 Development of Third Arm Subsystem

Several issues arose during the design of the third arm subsystem. The goal of this subsystem was to support the load of the kayak by making it feel weightless to the user; this phenomenon is illustrated by Figure 26. During the design process, the main issues that arose with this subsystem were its complexity and weight. For this design to work properly, it would have to be optimized for a specific load [8]. This would require many design and testing cycles to perfect, however, this is not the main issue. The main issue arises from the fact that optimizing for different loads would require different arm geometry and spring rates. This would mean that this design would not work for kayaks of all weights, unless the user swapped out the springs on their own. This is undesirable, as it decreases the overall ease of use for the device. The other primary issue with the subsystem was its size; during the design process, the team discovered that even when the third arm was made as small as possible and foldable, it would be difficult for a user to stow the third arm subsystem in the storage hatch of a kayak. The combination of these drawbacks led the team to decide to look for a more elegant solution.

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Figure 26: Iso-elastic Parallelogram

8.1.3 Development Cost and Time Constraints

The final, most important problems with the lower body exoskeleton and third arm combination are development time and cost. The Lockheed Martin FORTIS exoskeleton, shown by Figure 27 below, is very comparable to the team’s initial design concept. The FORTIS allows workers to hold a 36-pound tool in front of themselves as if it is weightless, and is coupled with a passive lower body exoskeleton [15]. This device costs over $20,000 new, which reflects the millions of dollars put into its development over several years by a team of experienced engineers. It is unlikely that the capstone team would be able to produce a comparable device without significantly more development time, money, and experienced team members.

Figure 27: Lockheed Martin FORTIS

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8.2 Design Review

The first design review was held with Professor Kowalski on Tuesday September 19th. The team presented the preliminary CAD design for the first time in conjunction with preliminary equations calculating the forces acting upon the user (Appendix A), based on a human factors book [2]. Key systems illustrated by the CAD included:

1. Pulley component, complete with a detailed a planetary gear system.

2. Simple lower body exoskeleton with embedded track included

3. A rough concept of the third arm mechanism.

Professor Kowalski highlighted issues relating to each of these systems. Regarding the planetary gear system, the cost of manufacturing each of the gear at a high enough quality, while still providing a low-cost point to the consumer, was a point of major concern. Similarly, the legs of the exoskeleton, as currently designed, could be subject to balance issues in addition to the gait issue, as mentioned in the prior section.

The second design review with Professor Livermore was held on Tuesday September 26th. At this point, the team had already contemplated a change in design direction and were aiming for a second opinion on the decision. The major concerns mentioned previously were presented and addressed. Additional concerns provided by Professor Livermore included; complexity of the spring-loaded arms when dealing with a potentially variable weight, difficulty in transferring the force from the legs of the exoskeleton to the legs of the user using a limited number of straps, as well as the issue of uncomfortable gait due to the limited degrees of freedom of the system. Given the now overwhelming design challenges regarding the exoskeleton, the team decided to commit to pivoting to an alternative, more effective and realistic idea.

8.3 Post-Design Review Research

8.3.1 Carrying Harness for Surfboards and the Like

This patent describes a method to carry surfboards or similarly shaped watercraft. This device, shown in Figure 28, consists of a sling system with a spreader bar to provide distance between the sling contact points. A strap connected to the spreader bar forms a loop meant to be supported by the user’s shoulder. This is a simple device with very few components and with proper materials it would be waterproof. However, a single strap carrying system produces a large and uneven load to be placed on only one of the user’s shoulders; this uneven load could cause the user pain and the uneven weight distribution could negatively affect the user’s posture and gait. [18]

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Figure 28: Carrying Harness for Surfboards [18]

8.3.2 Canoe Carrier Backpack with Collapsible Table

This patent details a rigid frame assembly with adjustable straps and webbing for an individual to carry a canoe over any terrain. The lateral support of the canoe would rest on the adjustable strap section at the top of the backpack frame. This device, seen in Figure 29, would allow a user to carry the canoe in a favorable position above the user’s head. A support system attaching to each end of the canoe would be used to stabilize the canoe as it is carried. This system also provides an expandable table, a useful additional feature. However, this carrying system is specialized for use with canoes as kayaks do not have the same lateral supports. Additionally, this carrying position is great for weight distribution of a canoe, but it would not allow for the preferred kayak carrying position. [19]

Figure 29: Canoe Carrier Backpack [19]

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8.3.3 Kayak Portage Harness and Method

This patent details both a kayak carrying harness and a method with which to use the device. This device, seen in Figure 30, consists of a harness that attaches over the kayak’s cockpit and is secured by two hull straps that surround the hull. This harness has two shoulder straps attached with which the user supports and carries the kayak on their back. This device has a novel mounting system that takes into consideration weight and ease of use. However, this carrying method is suitable only for shorter kayak types, not the significantly longer sea kayaks intended for the scope of this project. [20]

Figure 30: Kayak Portage Harness [20]

9 Final Design

With the design issues in mind, the principle methods for lifting and carrying the kayak have been adjusted. The two main goals of the project remain the same, to provide assistance in raising and lowering a kayak onto a car roof, and assisting in the on-foot transportation of the kayak.

Rather than two spring-assisted lifting arms, which would be long, complex and not fully effective, the car loading/unloading action of the design has been spun off into a simpler and separate design in the form of the telescoping arm assembly. This assembly will remain on the car at all points of the process and provide the assistance needed to easily raise or lower the kayak from the car roof without impacting the ability to use any other roof rack the user may already own. The assembly is designed with the intention of being easy to install or remove, lightweight, and provide a mechanical advantage as the user performs the loading/unloading action. Creating a separate assembly for the lifting allows for the design of a lighter and more compact harness system to facilitate carrying the kayak.

The original plan for on-foot transportation assistance was a two-pronged approach. The first prong balances the moment created by the kayak about the user’s center of gravity, by using a counterweight on the opposite side of the person. Ideally, this counterweight would be the user’s gear bag which they would have to carry to the water anyway. The second prong was to assist the user in lifting that force, now concentrated at their center of gravity, through a passive lower body exoskeleton. After considering the

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immense difficulty involved in designing such a system, a more practical analysis was employed. If given the choice, it is unlikely that the user would take the time and effort to put on such an apparatus, rather than simply walking to the water with their kayak, now perfectly balanced about their center of gravity. It is with this idea in mind that the on-foot transportation portion of the project has been modified to focus solely on moment balancing. Moving forward, the design will be centered around a harness with modular attachments. The harness would be made from a rigid material with foam padding for added comfort. The harness would hold components of two main subsystems; the first would be the moment balancer concept. One hip would hold a removable component which would hold the kayak, while the other hip would hold the gear bag, which would be extended outward at a variable distance to balance the moment on the kayak. The second subsystem would be a leg mounted pulley system which would be able to lift and lower the kayak between the waist level and the ground. All the subsystem components would be completely removed and stored in the kayak before paddling. The harness itself, would ideally be so subtle that it could be worn under a PFD while in the water.

9.1 Pulley and Kayak Hook Subsystem

The team chose to use a pulley to raise and lower the kayak from the hip. The pulley system for use in this system will provide a 5:1 mechanical advantage using off the shelf components. By utilizing four single pulleys arranged as seen in Figure 31 the desired mechanical advantage is produced for easy lifting and lowering of the hook subsystem and attached kayak. This system has an additional benefit of allowing the user to safely drop and remove the kayak load from the harness in the event of a fall by simply letting go of the rope.

Figure 31: Pulley System

The system shown by Figure 32 was designed to attach the kayak to the pulley system and the upper body harness. All the parts are off the shelf and easily assembled and meet the team’s needs with little to no modifications required. The subsystem consists of two pliable, high friction polyurethane-coated polyester

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straps that wrap around the kayak. The straps are each load rated to 1000 pounds, and are connected to a rigid bar using adjustable hardware. The adjustable hardware allows the lengths of the straps to be adjusted and for the kayak to be easily released.

Figure 32: Hooking System

9.2 Procedure

1. User arrives at kayak loading area, potentially parking 50-150 yards away 2. User puts on harness 3. User used telescoping arm to leverage kayak off the car 4. The kayak is then attached to the user at the hip 5. The telescoping arm folds back into its location on top of the car 6. The user walks to the loading dock with the kayak attached to the harness 7. Upon arriving at the water, the user lowers the kayak down to the water using a pulley system 8. User embarks on kayaking voyage

9.3 Design Challenges

The main design obstacles of the telescoping arm are weight, seize, deflection, and yield analysis. The material needs to be strong enough to resist deflection and yield when the load of the kayak is applied to the extended arm. Similarly, the arm needs to be light enough to facilitate easy operation and not to yield under its own weight. The size of the system is dependent on these previously mentioned design obstacles. The arm must resist deflection and yield, while keeping its size to less than 3” tall.

The main design obstacles of the harness are strength, comfort, modularity. The harness needs to be strong enough so that it won’t tear or break from the weight of the kayak, moment arm balancer, and pulley system. This strength will be achieved through material reinforcement which will have to be carefully balanced with ergonomic constraints. Finally, the detachable design of the harness components must not conflict with their stability during operation.

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9.4 Potential Impact

This product has the potential to further open the activity of recreational flatwater kayaking to people with lower thresholds of physical ability. Also, if this product were to gain a foothold in the industry, the team could pivot the major design concepts to apply to other heavy or awkward lifting scenarios.

10 Analysis & Testing

10.1 Moment Arm Analysis

After several iterations involving various spring configurations, aimed at reducing the overall bending moment about the user’s z-axis, it became evident that the bending moment could not be reduced without changing the external forces or their respective distances from the center of gravity of the system. This holds in accordance with the underlying concepts of forces and moments. With this in mind, a new goal was established: to distribute the bending moment as much as possible along the back. This idea will be expanded upon later in this section. Shown below in Figures 33-37 is the progression of static analysis on the frame/MAB design. Short calculations can be seen in Figure 34 while the complete calculations can be found in Appendix C.

Figure 33: Combined free body diagram of Moment Arm Balancer (MAB) and the backpack

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Figure 34: List of Forces

Figure 33 depicts the MAB/Backpack subsystem and all the external forces applied upon it. All the black forces are unknown variables. The weights were already known except for the weight of the MAB (Fw1). This was calculated given a set of dimensions and the assumption that it is a hollow aluminum tube. To evaluate the unknown forces, the system must be separated into individual free body diagrams.

Figure 35: MAB Free Body Diagram

Considering the established weights stated in Figure 34, in conjunction with the geometric values measured and presented in Figure 35, the two reaction forces where the MAB connects to the frame (FR1 and FR2) can be evaluated to be 72.597 lbs and -1.713 lbs respectively, through a sum of the moments about the z-axis (out of the page) and a sum of the forces in the vertical direction. These two reaction forces can then be applied to the model of the frame.

𝑎 = 33.5𝑖𝑛

𝑏 = 9.5𝑖𝑛

𝑐 = 14.5𝑖𝑛 𝑑 = 7.085𝑖𝑛

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10.2 Frame Analysis

Figure 36: Frame Free Body Diagram

Notice, in Figure 36, there are seven forces with four unknowns. To solve the problem, a kinematic compatibility condition must be established. In a worst-case scenario, there is too much load on the kayak side (right side) and the frame, which is a rigid body, tips over by rotating clockwise in this diagram. Were this the case, the point at which the left shoulder and left hip (symbolized by Fs1 and FH2) will lose contact with the body making the forces applied at those points zero. Just before the tip, the frame is still in the same place but the forces are still zero.

Figure 37: Frame FBD 2, compatibility condition and strap force

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The dotted diagonal lines in Figure 37, represent an extreme case for the frames tilted outer borders, or alternatively can be used to illustrate another attempt at solving the moment distribution issue. These lines can also represent the borders for a set of distributed loads, applied on the frame, linearly increasing as they get away from the center of gravity. Any section at which the dotted lines lie inside the solid frame, such as the upper left and lower right, is a section at which the distributive force provides a restorative moment, counteracting that of the kayak. The sections where the diagonal lines lay outside the frame, such as the upper right and lower left, the distributed load is equal to zero because the body can only push on the frame, it cannot pull it. This is the same reason Fs1 and FH1 are zero.

In attempting to quantify these distributed loads and their impact on the system, the loads were approximated as point forces at their respective centroids. At this point it was suggested that instead of creating a vest which had to be sewn in along the entirety of the pack, leaving it vulnerable to tears, it would be easier to use a couple extra straps. This is why, in Figure 37, there is an extra force, Fstrap-1 placed in one of the distributed load sections. With the addition of the compatibility condition, the system of now eight forces has three unknowns. Sum of forces in the horizontal and vertical directions were used with the sum of the moments about the center of gravity to evaluate Fstrap-1 Fs2 and FH2 to be 21.60 lbs, 78.88 lbs, and 21.60 lbs respectively.

The human body must provide a restorative moment on the frame through its various contact points to keep it from tipping over. The main place this moment affects is the back muscles. In order to make the user as comfortable as possible, this moment must be distributed along the back. As such, this idea of distribution has been established as a key metric for success. The introduction of Fstrap-1 is just preliminary. Ideally there would be 2-3 straps providing redundant support and spreading out the points on the back which provide restorative force. These straps were not introduced in the previous analysis because of difficulties applying Castigliano’s Energy Method to find deflection relations for the forces and thus an analytical solution to the problem.

10.3 Frame 2D Analysis

Preceding the test phase, the original frame and the simplified frame design were modeled in Abaqus to perform finite element analysis. The results of these two models were plotted and compared in terms of their resultant internal stresses and displacement given their respective material properties. This is shown in Figure 38 below.

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Figure 38: 2-D Abaqus FEA of test frame (left) compared to initial frame design, stress and displacement

The above analysis was displayed with the same scale limits for both designs. In other words, a given stress level is shown by the same corresponding color in both sides. From a design perspective, the initial frame design (right) is very similar to the test frame (left) with the top and bottom section cut off. This is because these sections make little difference to the frames internal stresses. In observing the displacement plot, the initial frame design experiences far less displacement than the test frame. Following the test of the left frame, the initial frame design was refined to meet specific key criteria, which will be covered later.

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10.4 Harness Testing

The team purchased an ALPS Outdoorz Commander Backpack Frame to try to get a better feel for the weight displacement and general comfortability that goes into a heavy-lift backpack frame. The Commander frame is a barebones backpack frame, consisting of a rectangular aluminum frame with three additional bars intersecting it, shown in Figure 38.

Figure 39: ALPZ Outdoorz Commander Frame

The team ordered an additional aluminum bar with a 1-inch outer diameter and length of 4 feet. This bar was connected across the back of the frame, similar to the existing bars, except it was offset with 8 inches protruding from one side and 24 inches protruding from the other. Weight was hung on the 8-inch protrusion varying from 10-60 pounds. The user then informed the group what their comfort level was on a scale of 1-10. This was repeated with an 11-pound counterweight hung on the 24-inch protrusion and the group tested a 16-pound counterweight on the same protrusion at the full 60-pound load. This test was repeated for three members of the group with varying body types to collect more accurate data. The test apparatus can be seen below in Figure 39. Figure 40, on the following page, shows the results of the study with no counterweight.

Figure 40: Test Apparatus

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Figure 41: Test with no counterweight

As one would expect, as the loaded weight at the hip increases, the user’s comfort level decreases. All users experienced a torque across the backpack caused by the immense off-balance present. The shoulder strap of the side without the load almost completely raised off the user’s shoulder, essentially transferring the total weight to the opposite shoulder. This is unacceptable because the shoulders are easily injured and have been a main consideration of the design. Figure 41, on the following page, shows the data collected using an 11-pound counterweight.

0

2

4

6

8

10

12

0 10 20 30 40 50 60 70

Com

fort

Lev

el

Loaded Weight (lbs)

Loaded Weight vs. Comfort Level (No Counterweight)

Subject 1 Subject 2 Subject 3

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Figure 42: Test with 11-lb counterweight

Looking at the graph, there is a definite peak of comfort level between the loaded weight of 30-40 pounds. This is because the 11-pound counterweight extended 24 inches from the body almost perfectly balances the moment which caused the backpack to torque about the load shoulder. With this in mind, the group decided to compare the 11-pound counterweight to the 16-pound counterweight, both at a load of 60 pounds. This data can be seen in Figure 42.

Figure 43: 11-lb vs. 16-lb counterweight

0123456789

10

0 10 20 30 40 50 60 70

Com

fort

Lev

el

Loaded Weight (lbs)

Loaded Weight vs. Comfort Level (11 lb Counterweight)

Subject 1 Subject 2 Subject 3

0123456789

10

11 16

Com

fort

Lev

el

Counterweight (lbs)

Counterweight vs. Comfort Level @ 60lbs

Subject 1

Subject 2

Subject 3

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Clearly, each user experienced a greater level of comfort at the 60-pound load with a 16-pound counterweight compared to the 11-pound counterweight. It should be noted that the 16-pound counterweight does not perfectly balance the moment created by the load. This test however, has set a limit of at least 16 pounds to be used as the counterweight. The group will continue testing with different counterweights and protrusion lengths until the risk of injury is eliminated and the level of comfort is maximized. The SOP for this test can be found in Appendix E.

10.5 Frame Refinement

Following the initial harness testing, the team focused on several areas to improve the design. These included various methods to achieve geometric compatibility and design for manufacturability.

10.5.1 Geometric Compatibility

Portability, or the ability for the product to fit inside the kayak’s compartment, was a key design requirement so the user would not have to make multiple trips to and from the car. Given geometric constraints of a 12.5 inch elliptical opening, width was seen as the most limiting factor. Given that a core component of the frame design was to have a long balancing bar extending out from the frame, the design had to be adapted. The long bar rigidly fastened to the frame was replaced with two shorter bars attached to the frame with hinges. These two bars would achieve the same extended length as the single bar, while achieving a compatible width when folded up. The addition of these hinges required slight adjustments to fundamental width of the frame.

Figure 44: Heavy Duty Hinge

Heavy duty hinges from McMaster, seen in Figure 44, were selected due to their durability. Because the user is expected to turn the hinge easily when stowing the frame, the center bolt is loosened so the hinge becomes a simple pin support. This is modeled as such in subsequent analysis.

Lacking any stops in them, the hinges can rotate freely through slightly more than 180 degrees. The hinges cannot allow for the moment arm balancing bars to rotate past a horizontal axis or the design will be compromised. To achieve this constraint steel cables were fed through holes in the MAB bars and designed to go through the frames vertical bars in a similar way. The cables would be at their maximum length when the bars were rotated to the horizontal axis.

10.5.2 Padding System

During testing it was found that there were several pressure points the harness frame created on the body. To solve this, a one inch thick layer of EVA foam padding was place between the frame and the user’s back. The EVA foam was wrapped in closed cell neoprene to prevent the foam from absorbing any ocean water. After additional testing, the foam padding significantly alleviated the pressure points on the user.

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10.5.3 Design for Manufacturability

Due to the inability of the machine shop to bend pipes at the radius required for the design of the cross members connecting the two main pipes, the curved members were replaced with a notched design with a rectangular cross section. The capstone machine shop was able to fabricate this updated design.

Figure 45: Pipe Bend design to Notch/Weld design, shoulder flanges

To compensate for the reduction in the frame width due to the hinges, the shoulder lift points were moved. Two new rectangular pieces were introduced to the top of the assembly instead of having the pin points between the 2 vertical pipes.

The notched cross members and the two external shoulder sections needed to be welded onto the pipes. Welding aluminum is difficult and very time consuming, so the team elected to switch to steel for ease of fabrication. In a future design, the frame will be converted back to aluminum. Due to the comparative higher strength of steel vs aluminum, the team was able to reduce the cross sectional widths of each part to minimize the weight and conform to available off the shelf components from McMaster.

10.5.4 Final Analysis

Considering the aforementioned design changes and the increased complexity of the design, a two-dimensional Abaqus model was no longer sufficient for finite element analysis. The final prototype was modeled in SolidWorks for FEA and fabrication purposes. The cables were not modeled but the appropriate forces were calculated and applied at their respective points.

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Figure 46: Final Frame design with arms extended

Figure 47: Final frame design with arms folded

New free body diagrams were constructed for the new segmented Moment Arm Balancer design, now in two pieces, the hinges, and the supporting cables. Below in Figures 48 and 49 the new moment arm bars are analyzed with their updated lengths and forces.

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Figure 48

Figure 49: Final Moment Arm Balancer Free Body Diagrams

The above free body diagrams for the moment arm balancing bars were used to identify the key unknown forces with standard sum of forces and moments statements. The results are shown below:

𝐹=>?@ABCD = 34.66𝑙𝑏

𝐹=>?@ABCG = 53.84𝑙𝑏

𝐹HBD = 34.65𝑙𝑏

𝐹HBG = 43.25𝑙𝑏

𝐹=>?@AJCD = 78.55𝑙𝑏

𝐹=>?@AJCG = 122.03𝑙𝑏

𝐹HJD = 78.55𝑙𝑏

𝐿B = 26.15𝑖𝑛

𝐿LB = 6.81𝑖𝑛

𝐹M = 10𝑙𝑏

𝐹NB = .59𝑙𝑏

𝜃 = 57.23°

𝐿J = 10.15𝑖𝑛

𝐿LJ = 6.81𝑖𝑛

𝐹Q>G>Q = 60𝑙𝑏

𝐹NJ = .23𝑙𝑏

𝜃 = 57.23°

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𝐹HJG = 61.80𝑙𝑏

Figure 50 Final Frame Design Free Body Diagram

The resulting final frame free body diagram (seen above) was analyzed with the compatibility condition. The condition states that as the frame is about to tip over, the left shoulder force and left hip force are equal to zero and the right shoulder and right hip displacements are zero.

The maximum hip and shoulder forces are shown below:

𝐹RJ = 74.73𝑙𝑏

𝐹SJ = 56.97𝑙𝑏

To properly constrain the frame model certain assumptions were held. First, no movement in the z direction was allowed. The shoulder on the kayak side was kept from moving vertically due to the kinematic compatibility conditions discussed above. For the same reason, the frame section at the hip level on the kayak side (the location in the above diagram as FH2) was horizontally constrained. Appropriate forces from the cables, hinges and the weight of the frame itself were applied at their respective locations.

𝑎 = 4.82𝑖𝑛

𝑏 = 11.30𝑖𝑛

𝑐 = 4.04𝑖𝑛

𝑑 = .69𝑖𝑛

𝑒 = 9.89𝑖𝑛

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Figure 51: Final Solidworks FEA Stress

The simulation results were promising. The plot above clearly shows that the maximum stress in the frame is 28.67 MPa, well below the yield strength of 460 MPa. The maximum stress point occurs at the through hole for the cable in the vertical section. During the fabrication phase, the team found that it was easier to loop the cable around the vertical pipes, negating the need for the through holes and making the frame easier to fold.

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Figure 52 Final Solidworks Displacement

57

Figure 53 Final Solidworks Factor of Safety

The maximum displacement calculated is approximately .15 mm and the minimum factor of safety is approximately 16. A couple caveats must be considered when interpreting the results. First, the welds were not modeled as welds, rather as one contiguous piece. Were accurate welding fillets and marks placed in the model it would probably make the joint sections stronger and change the locations of the higher stress points. Second, the simulation is only as accurate as its constraints, this was an issue with the final test. The hinges are made from aluminum and the frame is steel so the connection between the two could not be welded. Instead of welding them a set screw was used. When the frame was loaded, this set screw which clamped the hinges to the vertical pipes was not as stable as it should have been. This allowed the hinge to rotate around the vertical frame, destabilizing the system. In future designs this hinge will be welded to the frame.

10.6 Telescoping Arm

Having decided on the basic design of the telescoping arm, various calculations were required to identify a proper material and geometry. This required 3 different steps of analysis: determining the maxing load acting upon the beam due to the weight of the kayak, deflection analysis of various materials, and deflection and yield analysis of various geometric properties. A suitable off the shelf McMaster component could then be selected, matching the necessary material and geometric range, determined by the aforementioned analyses.

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To accurately calculate the deflection of the beam, a maximum load must be determined. When the telescoping arm is in use, it is extended approximately 3 feet (1m) from the car, and for all intents and purposes, a cantilever beam. A significant portion of the kayak’s weight will be applied to the end of this cantilever beam, and therefore it is vital the beam does not break or yield under this condition.

The first step was to determine this maximum load acting on the end point of the telescoping arm. To accomplish this, a simple case a beam supported at both ends with a centric load was used. In this example, show in Figure 43 below, the beam represents the kayak, the centric load is from the weight at its center of gravity, and the reaction forces at the supports are the ground and the end of the telescoping arm, respectively.

Figure 54: Kayak supported at both sides with a centric load

To solve this calculation, the force in the Y-direction and moment equations were derived from the free body diagram. There is no force in the X-direction and therefore no necessary equation.

∑𝑭𝒚: 𝟎 = 𝑨𝒚 +𝑩𝒚 −𝒎𝒌𝒂𝒚𝒂𝒌𝒈 Equation 2

∑𝑴𝑨:𝟎 = `𝟏𝟐𝑳𝒌𝒂𝒚𝒂𝒌d e𝒎𝒌𝒂𝒚𝒂𝒌𝒈f + (𝑳𝒌𝒂𝒚𝒂𝒌)(𝑩𝒚) Equation 3

Simplifying gives the following expression:

𝑩𝒚 = 𝑨𝒚 = `𝟏𝟐d e𝒎𝒌𝒂𝒚𝒂𝒌𝒈f Equation 4

The reaction forces at Ay and By will always be half the magnitude of the weight of the kayak. For example, if the kayak is being supported on one end by the user, and on the other end by the telescoping

59

arm, each is supporting 30 pounds, assuming the kayak weighs 60 pounds total. This 30 pound figure is the vital max load when considering deflection. This can be seen in Figure 44.

Figure 55: Telescoping Arm Deflection

Having determined the load acting upon the end of the 1-meter telescoping arm, analogous to a cantilever beam, a proper material must be selected. This is reflected in Figure 44. The materials were compared due to either their strength or cost. The best option would be the lowest cost material that could perform the required task of supporting the load without bending or yielding, while maintaining a functional size. With this in mind, the following materials and associated Modulus of Elasticity were analyzed:

1. Aluminum 6061 (68.9 GPa) 2. Steel 4130 (210 GPa) 3. ABS Plastic w/ High Modulus of Elasticity (3.1 GPa) 4. ABS Plastic w/ Low Modulus of Elasticity (1.4 GPa) 5. PVC Plastic (2.9 Gpa)

The deflection of each material was considered until the identical case. The parameters were the following:

• Length of Beam: 1m • Height of Beam = .0762m • Width of Beam = .05 m • Thickness of Beam Walls =1/4 In • Force of Kayak = 30 lbs

Based on these geometric conditions, the formula for the area moment was the following:

𝑰 = (𝒃𝒉𝟑

𝟏𝟐)𝒆𝒙𝒕𝒆𝒓𝒏𝒂𝒍𝒅𝒊𝒎𝒆𝒏𝒔𝒊𝒐𝒏𝒔 − (

𝒃𝒉𝟑

𝟏𝟐)𝒊𝒏𝒕𝒆𝒓𝒏𝒂𝒍𝒅𝒊𝒎𝒆𝒏𝒔𝒊𝒐𝒏𝒔 Equation 5

𝐼 = s0.050.0762t

12uADvAwx>@yz{Ax|z}x|

− s0.043650.06985t

12uzxvAwx>@yz{Ax|z}x|

= 6.0388 ∗ 10C�𝑚�

To calculate deflection, two different methods were used: Superpositioning method and Castigliano’s method. The superpositioning method looked at the deflection as a combination of two separate cases. The first case was that of a single point load acting upon the very end of the beam, the max load acting on

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the support due to the weight of the kayak, as determined in the previous section. This was given by the following equation:

𝜹𝒔𝒊𝒏𝒈𝒍𝒆𝒑𝒐𝒊𝒏𝒕𝒍𝒐𝒂𝒅 = 𝑭𝒌𝒂𝒚𝒂𝒌𝑳𝑩𝒆𝒂𝒎

𝟑

𝟑𝑬𝒎𝒂𝒕𝒆𝒓𝒊𝒂𝒍𝑰 Equation 6

The second case is that of a distributed load due to the weight of the material. This was given by equation 6.

𝜹𝒅𝒊𝒔𝒕𝒓𝒊𝒃𝒖𝒕𝒆𝒅𝒍𝒐𝒂𝒅 = (𝑨𝑩𝒆𝒂𝒎)(𝝆𝒎𝒂𝒕𝒆𝒓𝒊𝒂𝒍)(𝑳𝑩𝒆𝒂𝒎)𝟒

𝟖𝑬𝒎𝒂𝒕𝒆𝒓𝒊𝒂𝒍𝑰 Equation 7

The final value for the total deflection from superposition is the summation of the deflection from the two cases.

𝜹𝒔𝒖𝒑𝒆𝒓𝒑𝒐𝒔𝒊𝒕𝒊𝒐𝒏𝒊𝒏𝒈𝒕𝒐𝒕𝒂𝒍 = 𝜹𝒔𝒊𝒏𝒈𝒍𝒆𝒑𝒐𝒊𝒏𝒕𝒍𝒐𝒂𝒅 + 𝜹𝒅𝒊𝒔𝒕𝒓𝒊𝒃𝒖𝒕𝒆𝒅𝒍𝒐𝒂𝒅 Equation 8

The second method used to determine deflection and verify the superpositioning results was Castigliano’s method. This was given by equation 8 below.

𝜹𝑪𝒂𝒔𝒕𝒊𝒈𝒍𝒊𝒂𝒏𝒐�𝒔 = 𝑭𝒌𝒂𝒚𝒂𝒌𝑳𝑩𝒆𝒂𝒎

𝟐

𝟑𝑬𝒎𝒂𝒕𝒆𝒓𝒊𝒂𝒍𝑰+ 𝑪𝑭𝒌𝒂𝒚𝒂𝒌𝑳𝑩𝒆𝒂𝒎

𝑨𝑩𝒆𝒂𝒎𝑮𝒎𝒂𝒕𝒆𝒓𝒊𝒂𝒍 Equation 9

After verifying that the results from each method matched one another with only acceptably low differences, the best material was chosen. Table 4 shows a segment of results from different materials:

Table 4: Material vs. Deflection

Deflection: Single Load

Deflection: Distributed Load

Total Deflection: Superposition

Total Deflection: Castigliano's

Aluminum 6061 0.87 cm 0.0007 cm 0.87 cm 0.91 cm ABS (High E) 19.34 cm 0.0044 cm 19.35 cm 20.14 cm ABS (Low E) 42.83 cm 0.0098 cm 42.84 cm 44.60 cm

PVC 20.68 cm 0.0050 cm 20.68 cm 21.53 cm Steel 4130 0.29 cm 0.0007 cm 0.29 cm 0.30 cm

It is clear to see that Aluminum and Steel were the most promising choices of materials to proceed with. With these two main materials picked, deflection and yield analysis was done to determine the most suitable cross sectional area to use for the telescoping arm. To save time, the group used cross sectional areas that were also available to buy in either aluminum or steel from off the shelf components at McMaster-Carr.

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The above deflection analysis was repeated using the updated materials and available cross sectional areas. Failure theorems were then applied to each of the off the shelf parameters. These theorems calculated the safety factor based on the following equations listed in Table 5:

Table 5) Failure Theorem Formulas

Limited results of this analysis can be found in Table 6. Based on these results, two standard cross section areas were chosen and compared. They were a rectangular (2”x 2”) and circular (2”OD) cross sections.. Based on Professor Jallili’s professional advice, a part was chosen that resulted in a static yield factor of at least 5, and a failure theorem factor between 2-3. As the table indicates, the Aluminum with a circular cross section proved to be the best match for the design requirements.

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Table 6) Resulting Safety factor of Two Cross-Sectional Areas

Full Calculations may be found in Appendix D

10.7 Pulley Sub-system

The system will be used with 5/16” braided polyethylene rope that is rated to 2600 pounds. The system has a mechanical advantage of 5:1, meaning that for every pound of force exerted by the user, 5 pounds are exerted on the lifted load. For the assumed 60 pound kayak, the user will be expected to apply only 12 pounds of force to lift the kayak. Additionally, the length of rope pulled by the user will be five times that of the total vertical distance traveled by the load.

11 Project Management

Figure 56 on the following page details a Gantt chart which schedules work for the August-December term. The critical path largely consists of the building, testing, and iteration phases of the project. This implies any delays in finishing these specific tasks, past their stated deadline, would result in limited time on future tasks to maintain the agreed upon timeline.

Flexibility is built into the schedule with each task having been given a more lenient estimate of time necessary to complete. Slack time exists within IRB Approval and the Final Presentation tasks; 20 days and 9 days, respectively.

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Figure 56: Gantt Chart

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11.1 Future Improvements

The team had several ideas to improve the design if development continued past capstone. Due to time constraints, the harness prototype at the end of capstone was made from steel, since steel is easy to weld. Ideally, the harness frame material would be changed to aluminum with an anodized finish to reduce the overall weight of the system and provide greater corrosion resistance. The team would also get a larger pool of test subjects, and use their feedback and gathered data to improve the shape of the frame and padding. On the current prototype, the harness uses two hinges to connect the counterweight and kayak to the frame. Each hinge is supported by a cable when loaded, as shown by Figure 57, below. With future iterations, the cables would be eliminated, the hinges would self-lock at a 90-degree angle, and would support the full load placed on each bar. The team would add an additional horizontal strap connecting each backpack shoulder strap, to help further distribute the forces on the upper body.

Figure 57: Hinges and Cable Supports

11.2 Monitoring and Control

To ensure the project meets the deadline in the allotted time, the group will have internal meetings biweekly. One purpose of such meetings is discussing progress and consulting the Gantt chart, ensuring daily goals and milestones are being met. Weekly memos will be sent to advisor Kowalski, detailing work accomplished, upcoming work, and timeline status. In addition, a final review meeting will be scheduled

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with Professor Kowalski to close out to project, confirming all necessary work has been completed to satisfaction.

11.3 SWOT Analysis

A SWOT analysis is helpful to identify strengths and weaknesses within a group internally, and the opportunities and threats that may arise externally. Figure 47 on the following page is a SWOT analysis of the device for carrying a kayak.

Strengths Weaknesses

• Effectiveness of Solution: No other products fulfill challenges presented in the problem statement to the same extent

• Technical Ability of Group Members: Each group member has valuable experience in the field of engineering and problem solving

• Consumer Adoption: The device is unfamiliar and does not have an established market

• Unit Cost: While initial estimates are optimistic, cost analysis is not a strength of the group. Build costs may fluctuate due to material selection and other factors

Opportunities Threats

• Intellectual Prosperity: Design concept is innovative, unique, and non-obvious

• Lack of Dominant Competition: No other product meets the problem statement to an equal level of effectiveness

• Build Complexity: Multiple subassemblies increase complexity

• Competitor Products: A handful of products exist that fulfills parts of the solution to an effective extent

• Human Testing Approval: The IRB approval process is a unfamiliar task for the group

Figure 58. SWOT Analysis

12 Conclusion

The team has successfully addressed the problem of designing a portable device to assist in the transportation of a sea kayak, including lifting it on and off a car roof, as well as carrying it to and from the water, in a time efficient and cost-effective manner. Extensive background research has been done to determine the most applicable and effective technology to use with this problem. Various solutions were discussed, with the group identifying the final solution based on objective criteria in the decision matrix. Design steps, concept ideas, and feedback have been considered and documented, allowing the groups to take proper steps with securing IP. With a development plan set in place, the group looks forward to beginning work on a device for the improvement of carrying a kayak.

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13 Intellectual Property

13.1 Description of Problem

Professor Kowalski is an avid kayaker who is looking for a device to assist him in transporting his kayak. He currently loads and unloads his kayak from the roof of his car with no assistance, and drags the kayak to and from the loading dock using a pair of attachable wheels. These wheels must be stored in the car, so he is forced to drag the kayak to the loading dock, then return to the car to stow the wheels. Additionally, upon returning to the loading dock after kayaking, he must make the trip to the car to get the wheels, bring them back to the kayak and drag the kayak back to the car.

13.2 Proof of Concept

Although the team is in still in the early design phase, a final concept has been chosen to move forward with. The team has chosen to move forward with the Moment Arm Balancer and to move away from the lower-body exoskeleton, creating a device that provides strength assistance in loading and unloading a kayak on a vehicle, as well as assisting the user in transporting the kayak to and from the vehicle to either the garage or loading dock. This system will make use of a rigid body to displace the weight of the kayak in a comfortable manner.

13.3 Progress to Date

Thus far, the group has chosen a final concept to move forward with. Now that a path forward has been defined, the group will begin ordering necessary parts and move into the prototyping phase.

13.4 Individual Contributions

All members of the group have equally and adequately contributed to the development of the final concept and all progress made up to this point in time.

13.5 Future Work

As mentioned above, the group must decide which method will be used to provide the mechanical advantage needed for strength assistance. Once decided, the group can begin ordering parts, as well as the initial phases of testing.

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14 References

[1] T. A. Hunter, “Human Factors in Design,” in Engineering Design for Safety, 1st ed. New York, NY: McGraw-Hill, 1992, ch. 3, pp. 37–80.

[2] S. E. Gordon, Y. Liu, C. D. Wickens “Biomechanical Work,” in An Introduction to Human Factors Engineering, 1st ed. Reading, MA: Addison-Wesley Educational Publishers, 1998, ch. 11, pp. 327–335.

[3] Department of The Army (2002). Exoskeleton Power and Torque Requirements Based on Human

Biomechanics. Aberdeen Proving Ground, MD: Army Research Laboratory, pp. 21-22. [4] G. W. Brown, “Load and Torque Resistant Caliper Exoskeleton,” US9095981, 04-Aug-2015. [5] R. Angold, “Portable Load Lifting System,” US9333644, 10-May-2016. [6] A. DiGiulio, E. DiGiulio, G. W. Brown, and D. E. Wetzel, “Adjustable, iso-elastic support

apparatus,” US5435515, 25-Jul-1995. [7] A. Sacksteder, “Exoskeleton Arm Interface,” US9719633, 01-Aug-2017. [8] R. Altenburger, D. Scherly, and K. S. Stadler, “Design of a Passive, Iso-elastic Upper Limb

Exoskeleton for Gravity Compensation,” ROBOMECH Journal, vol. 3, no. 1, Dec. 2016. [9] “Thule Hullavator Pro | Thule | USA.” [Online]. Available: https://www.thule.com/en-

us/us/sport-rack/kayak-roof-racks/thule-hullavator-pro-_-1685448. [Accessed: 17-Aug-2017]. [10] “Thule Slipstream | Thule | USA.” [Online]. Available: https://www.thule.com/en-us/us/sport-

rack/kayak-roof-racks/thule-slipstream-_-196658. [Accessed: 17-Aug-2017]. [11] “Honda Worldwide | Walking Assist.” [Online]. Available: http://world.honda.com/Walking-

Assist/. [Accessed: 17-Aug-2017]. [12] “Ski braces that reduce pain and fatigue,” Ski~Mojo. [Online]. Available:

http://www.skimojo.com/. [Accessed: 17-Aug-2017]. [13] “Exosuits,” Lowe’s Innovation Labs. [Online]. Available:

http://www.lowesinnovationlabs.com/exosuits/. [Accessed: 17-Aug-2017]. [14] “HULCTM | Berkeley Robotics & Human Engineering Laboratory.” [Online]. Available:

http://bleex.me.berkeley.edu/research/exoskeleton/hulc/. [Accessed: 17-Aug-2017].

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[15] R. design, “Lockheed Martin FORTIS Human-Powered Exoskeleton | Industrial | ROBRADY

design | Total Product Development | Sarasota, Florida | Product Design,” 19-Sep-2014. [Online]. Available: https://robrady.com/design-project/lockheed-martin-fortis-human-powered-exoskeleton.

[16] C. S. Haines et al., “Artificial Muscles from Fishing Line and Sewing Thread,” Science., Vol.

343, Issue 6173, pp. 868-872, Feb. 2014.

[17] A. Norazam, R. Ramli, S. M. Haris, “Design and development of lower limb exoskeletons: A survey,” Robotics and Autonomous Systems, vol 95, pp. 102-116, Sept, 2017.

[18] D. Bear, “Carrying Harness For Surfboards and the Like,” US4804025, Feb-1989.

[19] D. Weatherall, “Canoe Carrier Backpack With Collapsible Table,” US6315177, 13-Nov-2001.

[20] P. Zwagerman, “Kayak Portage Harness and Method,” US6681968, 27-Jan-2004.

[21] M. Lafiandra and E. Harman, “The Distribution of Forces between the Upper and Lower Back during Load Carriage:,” Medicine & Science in Sports & Exercise, vol. 36, no. 3, pp. 460–467, Mar. 2004.

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15 Appendix A – Variables

Fb = lifting force (lbf)

k = spring constant (lbf/in)

a, b, and c = geometric lengths (in.)

ϕ = angle (°)

Fz = predefined load force (lbf)

𝐹B= Force at gear 1 (lbf)

𝑟B = Radius of gear 1 (in.)

𝐹J = Force at gear 2 (lbf)

𝑟J = Radius of gear 2 (in.)

𝐹Q>G>Q = Kayak Weight (lb.)

𝐹�M = Gear bag weight (lb.)

𝐹�B = Moment arm balancer weight (lb.)

𝐹�J = Frame weight (lb.)

𝐹RB = Shoulder 1 force (lbf)

𝐹RJ = Shoulder 2 force (lbf)

𝐹SB = Hip 1 force (lbf)

𝐹SJ = Hip 2 force (lbf)

Fstrap-1 = Force from chest strap (lbf)

𝑊Q>G>Q = Force from gravity at kayak (lbf)

𝑊v}w|} = Force from gravity at torso (lbf)

𝑊�}wA>w{C>xyC�>xy = Force from gravity at forearm and hand (lbf)

𝑊��AwC>w{ = Force from gravity at upper arm (lbf)

ℎ = height (in.)

𝑏 = base width (in.)

𝛼 = angle (°)

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𝑀?>LQC{�|L@A = Moment in the back muscle (lbf – in.)

𝑀@}>yC>xyCv}w|} = Moment from the load and torso (lbf – in.)

𝐹?>LQC{�|L@A = Force experienced in back muscle (lbf)

𝐹L}{�wA||z}x = Compression force (lbf)

𝐹A@?}N = Force at the elbow (lbf)

𝑊�}wA>w{C>xyC�>xy = Force at the forearm and hand (lbf)

𝐹|�}�@yAw = Force at the shoulder (lbf)

𝑀A@?}N = Moment at the elbow (lbf – in.)

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16 Appendix B – Human Factors Calculations

Typical Lifting Situation Constants:

𝑊Q>G>Q = 𝑊@}>y = 222𝑁

𝑊v}w|} = 350𝑁

𝑊�}wA>w{C>xyC�>xy = 16𝑁

𝑊��AwC>w{ = 20𝑁

ℎ = 40𝑐𝑚

𝑏 = 20𝑐𝑚

𝛼 = 55°

Back Muscle Moment-arm = 5 N-cm

Need:

𝑀?>LQC{�|L@A ≥ 𝑀@}>yC>xyCv}w|}

Calculations for Back:

𝑀@}>yC>xyCv}w|} = 𝑊@}>y𝑥ℎ +𝑊v}w|}𝑥𝑏

𝑀@}>yC>xyCv}w|} = 222𝑁𝑥0.4𝑚 + 350𝑁𝑥0.2𝑚 = 158.8𝑁 −𝑚

𝑴𝒃𝒂𝒄𝒌C𝒎𝒖𝒔𝒄𝒍𝒆 ≥ 𝟏𝟓𝟖. 𝟖𝑵 −𝒎

𝑀?>LQC{�|L@A = 𝐹?>LQC{�|L@A𝑥𝐵𝑎𝑐𝑘𝑀𝑢𝑠𝑐𝑙𝑒𝑀𝑜𝑚𝑒𝑛𝑡 − 𝑎𝑟𝑚

158.8𝑁 −𝑚 = 𝐹?>LQC{�|L@A𝑥0.05𝑚

𝑭𝒃𝒂𝒄𝒌C𝒎𝒖𝒔𝒄𝒍𝒆 ≥ 𝟑𝟏𝟕𝟔𝑵

𝐹L}{�wA||z}x = 𝑊@}>y𝑥𝑐𝑜𝑠(𝛼) +𝑊v}w|}𝑥𝑐𝑜𝑠(𝛼) + 𝐹{�|L@A

𝐹L}{�wA||z}x = 222𝑁𝑥𝑐𝑜𝑠(55°) + 350𝑁𝑥𝑐𝑜𝑠(55°) + 3176𝑁

𝑭𝒄𝒐𝒎𝒑𝒓𝒆𝒔𝒔𝒊𝒐𝒏 = 𝟑𝟓𝟎𝟒𝑵

Calculations for Arm:

Σ𝐹A@?}N = 0

72

𝑅A@?}N −𝑊�}wA>w{C>xyC�>xy −𝑊@}>y = 0

𝑅A@?}N − 16𝑁 − 111𝑁 = 0

𝑹𝒆𝒍𝒃𝒐𝒘 = 𝟏𝟐𝟕

Σ𝐹|�}�@yAw = 0

𝑅|�}�@yAw − 𝑅A@?}N −𝑊��AwC>w{ = 0

𝑅|�}�@yAw − 127𝑁 − 20𝑁 = 0

𝑹𝒔𝒉𝒐𝒖𝒍𝒅𝒆𝒓 = 𝟏𝟒𝟕𝑵

Σ𝑀A@?}N = 0

−16𝑁𝑥0.18𝑚 − 111𝑁𝑥0.36𝑚 +𝑀A@?}N = 0

𝑴𝒆𝒍𝒃𝒐𝒘 = 𝟒𝟐. 𝟖𝟒𝑵 −𝒎

Back:

𝑴𝒃𝒂𝒄𝒌C𝒎𝒖𝒔𝒄𝒍𝒆 ≥ 𝟏𝟓𝟖. 𝟖𝑵 −𝒎

𝑭𝒃𝒂𝒄𝒌C𝒎𝒖𝒔𝒄𝒍𝒆 ≥ 𝟑𝟏𝟕𝟔𝑵

𝑭𝒄𝒐𝒎𝒑𝒓𝒆𝒔𝒔𝒊𝒐𝒏 = 𝟑𝟓𝟎𝟒𝑵

Arm:

𝑹𝒆𝒍𝒃𝒐𝒘 = 𝟏𝟐𝟕𝑵

𝑹𝒔𝒉𝒐𝒖𝒍𝒅𝒆𝒓 = 𝟏𝟒𝟕𝑵

𝑴𝒆𝒍𝒃𝒐𝒘 = 𝟒𝟐. 𝟖𝟒𝑵 −𝒎

Conversion to English

73

17 Appendix C – Harness Calculations

Geometry Known Values Properties pipe_OD := 1 pipe_ID := 7/8 pipe_density := .1 =0.1 (lb/in^3) F_kayak := -60 F_gb := -10 Fw_backpack := -8 xlengths (in) Frame w := convert(.36, units, meters, inches) =14.17322835 shoulder_2_cog := convert(.1, units, meters, inches) 3.937007874= shoulder_1_cog := -shoulder_2_cog =-3.937007874 Bar (reference center of frame) L := 48 =48 gearbag_disp := -33.5 =-33.5 kayak_disp := L+gearbag_disp =14.5 bar_cog := kayak_disp-(1/2)*L =-9.5 bar_reaction_1 := -(1/2)*w =-7.086614175

74

bar_reaction_2 := (1/2)*w =7.086614175 ylengths(in) cog_shoulderline := 13.5 cog_lbline := -7.5 strap_1_line := 2.5 strap_2_line := (2/3)*cog_lbline =-5.000000000 Force Calculations Pipe: m_pipe := (1/4)*Pi*(-pipe_ID^2+pipe_OD^2)*L*pipe_density =0.8835729340 *Fw_pipe := -m_pipe* =-0.8835729340 *(lbm to lbf is 1) Sum of Moments about reaction point 1: F_reaction_2 := 0-(F_kayak*(kayak_disp-bar_reaction_1)+F_gb*(gearbag_disp-bar_reaction_1)+Fw_pip e*(bar_cog-bar_reaction_1))/(bar_reaction_2-bar_reaction_1) =72.59676946 Sum of Forces in y direction F_reaction_1 := 0-F_reaction_2-F_gb-Fw_pipe-F_kayak =-1.71319653 Frame: M1 := Matrix([ [shoulder_1_cog, shoulder_2_cog, strap_1_line, -bar_reaction_1, -bar_reaction_2, cog_lbline, -cog_lbline, 0], [1, 1, 0, -1, -1,0, 0, 1], [0, 0, -1, 0, 0, -1, 1, 0], [1, 0, 0, 0, 0, 0, 0, 0], [0, 0, 0, 0, 0,1, 0, 0], [0, 0, 0, 1, 0, 0, 0, 0],

75

[0, 0, 0, 0, 1, 0, 0, 0], [0, 0, 0, 0, 0, 0,0, 1]]) =

⎣⎢⎢⎢⎢⎢⎢⎡−3.937007874 3.937007874 2.5 7.086614175 −7.086614175 −7.5 −7.5 0

1 1 0 −1 −1 0 0 10 0 −1 0 0 −1 1 01 0 0 0 0 0 0 00 0 0 0 0 1 0 00 0 0 1 0 0 0 00 0 0 0 1 0 0 00 0 0 0 0 0 0 1⎦

⎥⎥⎥⎥⎥⎥⎤

M2 := Matrix([ [0], [0], [0], [0], [0], [F_reaction_1], [F_reaction_2], [Fw_backpack]])

=

⎣⎢⎢⎢⎢⎢⎢⎡

00000

−1.7131965372.59676946

−8 ⎦⎥⎥⎥⎥⎥⎥⎤

M3 := 1/M1 M4 = M3 . M2

=

⎣⎢⎢⎢⎢⎢⎢⎡

𝐹|B𝐹|J

𝐹|vw>�CB𝐹HB𝐹HJ𝐹SB𝐹SJ

𝐹N_?>LQ�>LQ⎦⎥⎥⎥⎥⎥⎥⎤

=

⎣⎢⎢⎢⎢⎢⎢⎡−4.797 ∗ 10

CB®

78.88421.604−1.713272.5970

21.604−8 ⎦

⎥⎥⎥⎥⎥⎥⎤

lbs

76

Final Design Maple Calculations MAB side

Weight := 10;

=10

pipelength1 := 26.15*(1/12);

=2.179166667

pipeOD := .75*(1/12);

=0.06250000000

pipeID := .52*(1/12);

=0.04333333333

pipe1volume := evalf((1/4)*Pi*(-pipeID^2+pipeOD^2)*pipelength1);

=0.003471757590

Aldensity := 170;

=170

pipeweight1 := Aldensity*pipe1volume;

=0.5901987903

77

Lv := 10.58*(1/12);

=0.8816666667

Lh := 6.81*(1/12);

=0.5675000000

Angle := arctan(Lv/Lh);

=0.9988858086

angledeg := evalf(180*Angle/Pi);

=57.23194104

Length := 27.96*(1/12);

=2.330000000

hingedist := Length-pipelength1;

=0.150833333

DistanceToCable := Lv;

=0.8816666667

DistanceToFrame := evalf(DistanceToCable/tan(Angle));

=0.5674999998

CableLength := sqrt(DistanceToCable^2+DistanceToFrame^2);

78

=1.048519128

CableForce := evalf((Weight+(1/2)*pipeweight1)*pipelength1/((DistanceToFrame-hingedist)*sin(Angle)));

=64.03304710

CableForceX := evalf(CableForce*cos(Angle));

=34.65721632

CableForceY := evalf(CableForce*sin(Angle));

=53.84336986

HingeForceX := CableForceX;

=34.65721632

HingeForceY := CableForceY-Weight-pipeweight1;

=43.25317107

Kayak Side

Weightb := 60;

=60

pipelengthb := 10.15*(1/12);

79

=0.8458333333

pipeOD := .75*(1/12);

=0.06250000000

pipeID := .52*(1/12);

=0.04333333333

pipebvolume := evalf((1/4)*Pi*(-pipeID^2+pipeOD^2)*pipelengthb);

=0.001347546445

Aldensity := 170;

=170

pipeweightb := Aldensity*pipebvolume;

=0.2290828956

Lvb := 10.58*(1/12);

=0.8816666667

Lhb := 6.81*(1/12);

=0.5675000000

Angle := arctan(Lvb/Lhb);

80

=0.9988858086

angledeg := evalf(180*Angle/Pi);

=57.23194104

Lengthb := 11.96*(1/12);

=0.9966666667

hingedist := Lengthb-pipelengthb;

=0.1508333334

DistanceToCableb := Lvb;

=0.8816666667

DistanceToFrameb := evalf(DistanceToCableb/tan(Angle));

=0.5674999998

CableLengthb := sqrt(DistanceToCableb^2+DistanceToFrameb^2);

=1.048519128

CableForceb := evalf((Weightb+(1/2)*pipeweightb)*pipelengthb/((DistanceToFrameb-hingedist)*sin(Angle)));

=145.1267644

CableForceXb := evalf(CableForceb*cos(Angle));

=78.54834175

81

CableForceYb := evalf(CableForceb*sin(Angle));

=122.0325192

HingeForceXb := CableForceXb;

=78.54834175

HingeForceYb := CableForceYb-Weightb-pipeweightb;

=61.80343630

Frame Calcs;

Frameweight := 3.91;

=3.91

Lengths;

cogshoulderx := 4.82*(1/12);

=0.4016666667

cogshouldery := 11.30*(1/12);

=0.9416666667

cogcablex := 4.04*(1/12);

=0.3366666667

cogcabley := .69*(1/12);

82

=0.05750000000

coghingex := 4.04*(1/12);

=0.3366666667

coghingey := 9.89*(1/12);

=0.8241666667

cogstrapy := 5.5*(1/12);

=0.4583333333

a := cogshoulderx;

=0.4016666667

b := cogshouldery;

=0.9416666667

c := cogcablex;

=0.3366666667

d := cogcabley;

=0.05750000000

e := coghingex;

83

=0.3366666667

f := coghingey;

=0.8241666667

g := cogstrapy;

=0.4583333333

Sum*of*Forces in the*Y

Fs2 := CableForceY+CableForceYb-HingeForceY-HingeForceYb+Frameweight;

=74.72928170

Sum*of*Moments*about*COG

Fhipb := (-Fs2*a-c*CableForceY+c*CableForceYb-d*CableForceX+d*CableForceXb+e*HingeForceY-e*HingeForceYb+f*HingeForceX-f*HingeForceXb)/f;

=-56.97193125

18 Appendix D – Telescoping Arm Calculations

See Attached

84

85

19 Cost Analysis

86

20 Appendix E – Harness Testing SOP

20.1 Purpose

This document describes the procedure for Weight Displacement on a Rigid Backpack Frame. Weights varied between 10 and 60 pounds will be attached to a rigid backpack frame to gain further understanding into how weight is displaced through the backpack frame. The wearer will don the rigid backpack and will express his/her comfort level as each weight is attached, with safety being the top priority. This can be seen below, in Figure 48.

87

Figure 59: User Wearing the Rigid Backpack

The backpack used for this test is the ALPS OutdoorZ Commander Freighter Frame which is a heavy-load carrying backpack used for hiking and hunting. It is a heavy-duty aluminum frame with a durable lashing system, adjustable shoulder harness, padded waist belt and shoulder straps. The frame weighs 5 pounds and can hold weights between 60-80 pounds comfortably.

This test will be conducted to acquire relevant data for the group’s Capstone project. The group is designing a backpack that will allow a person to carry a kayak comfortably, hands-free.

20.2 Scope

This SOP is intended for the Capstone group only, to collect data relevant to the project described above.

20.3 Pre-requisites

An ALPS OutdoorZ Commander Freighter Frame is required. Weights ranging from 10-60 pounds in 10 pound increments are required. These weights are metal-disk weights found in the Capstone lab.

A 1 inch diameter metal pipe with quad-clamps is required to be attached to the pack frame. The total length of the pipe is 4 feet, attached to the perpendicular portion of the frame on each side, centered around the frame’s center. Two rubber stoppers are required to prevent sliding of the weight. This load bar will be attached to the backpack frame as a permanent fixture, prior to this test. This setup can be seen in Figure 2 in the procedure section.

A table comparing weight to level of comfort is needed for the test. Three people are required, one frame wearer, one spotter and one recorder.

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20.4 Responsibilities

Three people from the Kayak Capstone Group are required for this procedure. One person will wear the backpack to which the weights will be attached. The second person will “spot” the backpack wearer by being in a position to swiftly grab the weight if the wearer experiences discomfort. The third person will record the level of comfort the backpack wearer experiences at the various weights. All three positions will rotate between the group.

20.5 Procedure

This procedure is only meant for the Kayak Transportation group in Fall Capstone II 2017; three members of the group must be present. No person outside of this group may partake in this test. All three positions will rotate through the group so each person will have a chance to wear the backpack, in order to collect data across all body types.

1. The wearer dons the backpack frame and the spotter moves into a position below the weight to grab it, if he experiences too much discomfort. The wearer will inform the spotter to grab the weight, relieving him of the stress immediately, by saying the word “spot.”

2. The 10-pound weight is attached to the end of the load-bearing arm, secured by the two rubber stoppers.

3. The wearer will speak a number between 1 and 10 describing his comfort level, with 1 being the most uncomfortable and 10 being the most comfortable. If he says the numbers 1-3, the weight will be removed immediately by the spotter.

4. The recorder will record the comfort level at the specified weight. 5. The weight will be removed and the next weight will be attached, increasing in weight by 10

pounds. 6. Repeat steps 3-5.

This test will be repeated with every member of the group wearing the backpack, to collect data across multiple body types as mentioned above.

This setup can be seen in Figure 49.

89

Figure 60: Test Apparatus

20.6 References

A report by M. LaFiandra & E. Harman titled, “The Distribution of Forces between the Upper and Lower Back during Load Carriage” was the initial inspiration for this test and had a plethora of references that were relevant.

“An Introduction to Human Factors Engineering” by C. D Wickens, S. E. Gordon and Y. Liu provided insight into typical lifting situations and the forces present in the lower back and shoulders. This lifting situation was crafted with the information from this textbook in mind.

20.7 Definitions

The problem statement for the group’s Capstone project is as follows:

“Develop a portable device to assist in the transportation of a sea kayak, including lifting it on and off a car roof, as well as carrying it to and from the water, in a time efficient and cost-effective manner.”

This test will be used to gain a better understanding into how the kayak can be attached to the person safely and carried comfortably.

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DEVICE FOR THE IMPROVEMENT OF CARRYING A KAYAK › uploads › 8 › ...Device for Improvement of Carrying a Kayak Design Team Nick Herman, Nick Graham David Landerman, Mike Santry

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