Team 1712: Assistive S.T.A.N - University of Connecticut€¦ · Final Design Components Final Prototype Future Improvements Budget/Timeline. Purpose and Background To design a robotic

Team 1712: Assistive S.T.A.N.D

ECE: Hannah Strickland, Bilal Khan, Edward Sango, Blerand QeriqiBME: Ashley Vanaman, Andrew Cohen, Kristen Campbell, Lisa Deconti,

and Sarah VetranoAdvisors: Dr. Shalabh Gupta and Dr. Krystyna Gielo-Perczak

Outline● Purpose and Background● Design Requirements and Restraints● Biomechanical Analysis● Final Design

○ Components○ Final Prototype○ Future Improvements

● Budget/Timeline

Purpose and Background● To design a robotic ankle device that assists patients from sit to stand

○ May not provide 100% assistance

● Sit to Stand (STS)○ Requires Plantar and Dorsiflexion○ Four Phases

■ Flexion Momentum phase■ Momentum Transfer Phase■ Extension Phase

● Center of Mass directly over the Knee and Ankle joints■ Stabilization Phase

Design Objectives and Constraints

● Size of Patients○ Max Weight 200 lbs

● User-Friendly○ Lightweight ( has to be under 5 lbs, goal under 3 lbs)○ Adjustable○ Comfortable○ Safe

● Durable○ Weather resistant

● Low Cost

Biomechanical Analysis● Force Platform

○ Forces, moments and center of pressure exerted on the ground

● Anybody software○ Simulation of a skeleton during STS over a 5 second

duration.○ Explains forces and muscle activity

● EMG○ Shows muscle activity during STS

Anybody confirmed our data from EMG and Force Platform

Biomechanical AnalysisWhat We Found

● Max force reached: 95% of subject weight, with both feet on the platform, one foot is about 45-50%

● The gastrocnemius and soleus are the two main muscles used in the calf for the sit to stand motion

● Muscle activity down the front of the calf we were able to see that these muscles provide less of the force and more of the balance

Final Schematic

Artificia

l Muscl

e

Force Sensor

Actu

ator

Components● Brace

○ 3D printed■ Inner calf support■ Inner foot support■ Box for spring■ Foot piece for additional comfort

● One for both left and right foot○ Aluminum

■ Structural support○ S-brackets to attach components○ Velcro to attach to the patient

Components● Actuators

○ Max Force: 33lbs○ Weight: .73 lbs each○ Speed: .44 inches/sec○ Stroke: 2 inches○ Using 12 V/DC at .17 amps

● Artificial Muscle○ Parts

■ Silicon tubing■ Cross-linked Techflex tubing■ (2) 1.75” aluminum rod, d = .5”

● One with ⅛” hole for airflow

■ Brass connector pieces (2)■ Stainless Steel Hose clamps■ Air compressor

● 50 psi○ Force Generated: TBD

Components ● FlexiForce A301 Sensors

○ Force Sensed ■ High 445 N(0 -100lbs)

○ Modifiable Range■ Change the Voltage Drive: -1.2V■ Adjusting Resistance of Rf: 100k Ohms

● Tenergy NiMH Rechargeable Batteries ○ 12V○ Rechargeable

● Microcontroller○ Arduino Mega 2560○ Arduino Motor Shield Rev 3

Pseudo-Code Diagram For Control System● Consistent of 3 Main Parts

○ Acquisition

○ Processing

○ Activation of

Mechanical System

Resulting Prototype● Weight

○ With all parts: 5lbs

● How it Works○ As of today: When apply a force to the sensors,

the sequence begins

● Testing ○ Sequencing○ Without test subject:

■ Proof of concept

Conclusions and Further improvements● Objectives met:

○ Comfortable: Felt insert, Foot insert○ Adjustability: Foot insert one for left and right○ Safety: Maximum time for sequence, all components are RoHS compliant○ Can hold up to 200 lbs

● Future testing:○ Connect to EMG to test subject while wearing the brace○ Improve artificial muscle

Budget

● Total Budget○ $2,000

● Total Expenses○ $1,532.58

● Budget Left Over○ $467.42

Timeline

Questions?

Components● Power Supply

○ Tenergy NiMH Rechargeable Batteries ■ 12V■ 10,000mAh■ Battery Charging Current: 1A

○ Tenergy NiMH Universal Charger■ Output 12V, 1A or 2A■ Temperature sensor to protect from

overheating. ■ Selection on 1A or 2A

● Planned to Build One. ○ Budget allowed for more expenses○ Battery Chosen fits our criteria

Components● Arduino Mega 2560

○ Operating Voltage 5V○ 54 digital input/output pins○ 16 analog inputs

● Arduino Motor Shield Rev 3○ Operating Voltage 5V to 12V○ Capabilities

■ Distribute Voltage/Current■ Step Down/Up Voltage■ L298: Full Bridge Driver■ Stackable With Mega 2560

Final Design Information