Critical Design Review - WordPress.com · 2019. 1. 11. · Critical Design Review Bearcat Ballistics 2018-2019 1. USLI Team Overview Project Plan Rocket Team Payload Team Safety Budget

Critical Design ReviewBearcat Ballistics 2018-2019

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USLITeam Overview

Project PlanRocket Team

Payload TeamSafety

Budget

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Overview

NASA University Student Launch Initiative (USLI)

● Annual Competition hosted at the Marshall Space Flight Center

● Gives an opportunity for engineering students to collaborate on a project

involving building a full scale model rocket○ Helps students gain valuable experience in a professional setting while simultaneously

completing hands-on tasks

● Our Mission: Rover Deployment with Soil Recovery and Rocket Launch

at Altitude

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Meet the Team

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Team Launch Vehicle Requirements● Conor is Launch Vehicle Team Lead● Subsystems of the Launch Vehicle:

○ Motor○ Fins○ Recovery○ Telemetry and Electronics○ Computing

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2.4.3

Recovery system must bring the rocket to the ground within 90 seconds of reaching apogee. Testing

The team shall test the recovery system’s ability to reach the ground from apogee within the predetermined time.

Team Payload Requirements● Andy is Payload Team Lead● Subsystems of the Payload:

○ Rover Power○ Deploy Power○ Rover Structures○ Deploy Structures○ Computing○ Excavation

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3.1.4

The payload shall be capable of withstanding sustained acceleration of up to 10 Gs. Analysis

Simulations shall be conducted and flight data shall be analyzed to measure the acceleration force the payload will withstand.

Team Safety Requirements● Adam is Safety Team Lead● Subsystems of Safety:

○ Training○ Housekeeping

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4.2.1

Every team member shall return all supplies they use while in the Rocket Lab to the correct place prior to leaving for the day, both as a safety precaution and good housekeeping process. Demonstration

Team members shall demonstrate good habits of putting supplies in their proper location for the safety of those using the lab.

Team Finance Requirements● Alex is Finance Team Lead● Subsystems of the Finances:

○ Budget○ Sponsorship Revenue○ Travel Expenses○ Reserve

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5.1.1

The budget shall be closely monitored and analyzed by the team treasurer throughout the design and build process to ensure that the budget is not exceeded. Inspection

The team treasurer shall inspect the team expenses and budgeting process during the length of the project.

Launch Vehicle OverviewMission Criteria and Design Driving Factors

Final Design OverviewDesign Evolution

SubsystemsFlight Events

TestingSubscale Performance

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Mission Success Criteria and Design Driving Factors1) The launch vehicle shall reach an apogee of +/- 100 ft of 5,000 ft AGL.2) The launch vehicle shall touch down from apogee in under 90 seconds.3) The launch vehicle shall deploy a soil sample rover payload.4) The launch vehicle shall deploy recovery devices in order to achieve a landing energy per section of

less than 75 ft-lbf. 5) The launch vehicle shall be constructed in a manner such that it is reusable.

Primary Design Driving Factors● Rocket motor ● Payload dimensions and mass● Fins● Recovery system

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Finalized Design Overview● Weight on Launch Pad (Lbs): 36.6● Descent Weight (Lbs): 29.1● Length (in): 126.0● Motor: Cesaroni L1050● Thrust-to-Weight Ratio (Avg Thrust): 6.42● Stability Margin (at launch): 2.19● Rail Exit Velocity (ft/s): 68● Total Landing Energy (ft-Lbf): 101.1● Avg. Max Altitude (ft): 5447

Center of Gravity73.8” from Nose

Center of Pressure90.6” from Nose

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Design Evolution

Review Stage

Motor Length (in)

Outer diameter

(in)

Launch Mass (Lbs)

Descent Mass (Lbs)

Stability Margin

at Launch

Simulated Altitude

Achieved (ft)

Proposal CTI L850W 113.5 7.75 37.7 33.1 2.08 4897

PDR AMW L900RR

122 7.67 / 6.16 31.9 28.0 2.24 5556

CDR CTI L1050 126 7.67 / 6.16 36.6 29.1 2.33 5436

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Subsystems - Transition Structure

1 - Payload Bay2 - Drogue Bay3 - Altimeter Bay4 - Structure Housing5 - Main Parachute Bay6 - Telemetry Bay

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Subsystems - Recovery SystemRequirement for each separated section to land with energy

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Launch Vehicle Electronics and Recovery Subsystem

Primary Battery

Primary Altimeter

Secondary Battery

Switch Switch

Secondary Altimeter

Secondary Main Parachute

Ejection Charge

Primary Main Parachute

Ejection Charge

Secondary Drogue

Parachute Ejection Charge

Secondary Drogue

Parachute Ejection Charge

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Altimeter Circuit

Telemetry Circuit

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GPS

Transmitter

IMUBattery

Microcontroller with Shield

Launch Vehicle Electrical Components1. Altimeters

1.1. Perfectflite StratologgerCF1.1.1. Power: 9V battery1.1.2. Calibration Accuracy +/- 0.5% typical

2. Telemetry2.1. Arduino Microcontroller w/ HamShield (VHF/UHF transceiver)

2.1.1. Frequency 400-520 Hz2.2. SparkFun IMU Breakout - MPU-9250

2.2.1. 3-axis accelerometer, 3-axis magnetometer and 3-axis gyroscope2.2.2. Output sample rate 4-8000 Hz2.2.3. Max : +/- 16 g’s

2.3. Smiley Antenna Tri Band 2 meter/220/4402.3.1. Frequency 440 Hz

2.4. Adafruit Ultimate Breakout GPS2.4.1. Refresh rate 10 Hz

2.5. E-flite 2s LiPo Battery 30C (7.4V/400mAh)

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Launch: Vehicle leaves the launch

pad Landing: Launch vehicle returns to ground with less

than 75 ft.-Ibf. Kinetic energy

510 ft. AGL: Main parachute deployed by

StratologgerCF Altimeter

Apogee: Launch Vehicle reaches target altitude of

5000 ft. and drogue parachute deploys

Flight Events

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TestingTesting Method

● Drop Test - Dropping vehicle from height to mimic landing force● “Pop” Test - Firing black powder charges at ground level to ensure body tubes separate● Shake Test - Vehicle experiences vibration under acceleration● CFD - Ansys, particular focus on transition section and fins● FEA - Siemens NX● Bending Test - Hanging weight on one end of the vehicle to the point of failure● Telemetry and Electronics - Test to ensure proper shielding & function● Subscale launch● Full-scale launch

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Subscale 1 PerformanceLength

(in)Outer

Diameter (in)Static

Margin EngineAvg. Thrust

(N)

Subscale 1 68 4.02 / 3.13 2.20 AT J420R 420.0

Full-Scale 126 7.67 / 6.16 2.33 CTI L1050 1046.1

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Subscale 1 Performance cont.Subscale 1 Weight (Lbs) CG

(in. from nose)

Simulated 10.4 38

Measured 12.1 ~40

Subscale 1 Lessons Learned● Manufacturing process & challenges● Vehicle stable in-flight● Ensure battery and wired connections

secure● Approximate mass creep metric

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Subscale 2 Performance

Vehicle Length (in)

Outer Diameters

(in)

Static Margin

Engine Simulated Altitude (ft)

Actual Altitude (ft)

Subscale 1 68 4.02 / 3.13 2.20 AT J420R 2560 Unknown

Subscale 2 39 2.25 / 1.8 2.08 Estes E30-7T 781 578

Full Scale 126 7.57 / 6.16 2.33 CTI L1050 5447 TBD

Payload DesignPayload Objective

Changes Since PDRMechanical Design

Electrical DesignExcavator Design

Deployment DesignGround Station

Weight BreakdownTesting

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Payload Mission Objectives● Deploy safely and travel 10 feet from the launch vehicle● Collect a soil sample

○ Sample must be at least 10 mL○ Sample must be stored in an on-board container

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Changes Since PDR● Volume change: Floor and ceiling of rover lowered/raised, respectively

● Changed soil collection system from auger to hole saw

● Swapped out L298N motor drivers with MC33926 to meet requirements of our motors

● Counter-torque arm now uses a single omnidirectional wheel

● Actuation of drill is now performed with a dc motor, rack and pinion rather than a linear actuator

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Payload Launch Vehicle InterfaceRover mounts to the actuator by means of a HIPS pistonhead, detailed in the document, with a 0.5” lip around the circumference.

Rover mounts to nose cone with a similar 3D Printed HIPS disk.

The rover is not fixed to these mounting points, but instead rests on them, allowing it to free itself upon deployment.

The linear actuator is bolted to a bulkhead 23” aft of the back end of the rover.

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CAD Photos of Payload Interface

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Actuator Mounting to Bulkhead

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Note: Servo is hidden behind the actuator. Xbee and battery not pictured.

Stowed vs Deployed

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Deployment Electronics● Arduino Uno

- Controls Retention Servo- Controls actuator deployment

● Xbee- Receives activation signal from

Ground Station ● Venom LiPo 11.1 Volt Battery

- Power for the Actuator● Brushless DC Motor Controller

- Provide motor control to actuator● Servo

- Releases Active Retention System● 6 pack 1.5 v battery

- Power for Arduino

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Design: Rover Chassis● Rover chassis is to be 3D printed from HIPS● Drive motors mount to sheet metal plates at either end of the chassis● Threaded rod runs through sleeves on the outside of the chassis

○ Handles compressive loads from deployment actuator○ Allows sections of the chassis to slide into place for assembly (“stacking”)

● Mounting holes and mating structures are included in the chassis○ Holes for electronics standoffs○ Sleeve for drill○ Clevis for counter-torque arm

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Rover Chassis: Exploded View

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Design: Counter Torque Arm● Rover will use a deployable arm to

counteract the motor torque● Arm will be custom made from HIPS● Uses torsion springs to deploy● Arm supports a single 40 mm diameter

omni wheel

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Design: Drive Motor Electronics● Wheels driven by two Cytron 12V 16.7RPM 270:1 Gearmotors● Motors will have a 0.1 µF capacitor soldered across their terminals for noise

suppression● Motors driven by Pololu’s MC33926 motor drivers

○ Can handle 3A continuous, which is well above our motor’s stall current○ Provides protection against back emf and overheating○ Takes two digital pins and one PWM-enabled pin per motor

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Design: Drill Electronics● Pinion gear is driven by a Cytron 12V 16.7RPM 270:1 gearmotor

○ Same motor that drives the wheels● Drill will be driven by a 25 mm diameter Pololu gear motor

○ Gear ratio may be 47:1, 75:1 or 99:1 pending tests with the hole saw● Drill motor will include an encoder

○ Drill can measure time taken to accelerate to full speed to determine whether soil is collected

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Design: Counter-Torque/Drill Sled Servos● Servos run on 6V supply● Servos will be run directly from Arduino pins

○ Pins can provide 5V, servos will be running at reduced capacity● Servos will be used to deploy the counter-torque arm

and the drill sled

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Design: Excavator

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● Hole saw attaches to the motor shaft via a 3D printed arbor

● A gear motor rotates a pinion gear to extend/retract the hole saw

○ Motor provides up to 194.4 oz-in of torque○ Gear has 16 mm radius○ Produces maximum 19.3 lb translational force○ Determines position with encoder feedback

● Upon soil collection, the drill chamber seals itself○ Spring loaded plate slides below drill

Excavator: Exploded View

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Payload Electronics Overview● Arduino Mega

○ Control Center● MC33926 Driver

○ Regulates speed with PWM○ Controls direction with H-bridge

● IMU ○ Will sense acceleration, attitude and

heading to create a “drive straight” system

○ Communicates w/ uno via I2C

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Weight Breakdown - Rover

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Component Mass (g)

Wheels, hubs and fasteners 601.532

Chassis 1620.8

Drive Motors 320

Winch/Drill Motors 274

Drill and Accessories 86.4

Drill Sled and Accessories 36.5

Battery 390

Printed Circuit Boards 54

Counter Torque Arm and Accessories 77.2

Misc (Wires, epoxy, smaller fasteners, etc.) 250

Total 3710.432

Weight Breakdown - Deployment System

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ComponentComponent Mass (g) Quantity

Mass of Group (g) Source of info

Actuator 1464 1 1464 Measured in labArduino 25 1 25 Manufacturer dataServo 45.5 1 45.5 Manufacturer dataBulkhead 250 1 250 EstimateBattery 390 1 390 ManufactureMotor Driver 113 1 113 ManufacturePiston Head 250 1 250 Estimate

Misc 150 1 150 Misc/Conservative Safety FactorTotal 2687.5

Ground Station ● Transmitter - 915 Mhz off the shelf antenna● Receiver - Two Yagi-Uda Antennas● Radio Transceiver - Digi XBee Pro SX

○ Controlled by an Arduino Uno● GUI to be coded using Python● Current Critical Figures of Merit

○ GPS Data○ Altimeter Data○ IMU Data○ Field Diagram

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Safety Overview

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Human SafetyHazard Analysis Matrix

Environmental SafetyFailure Modes and Effects Analysis

Human SafetyPPE tables covering all hazardous operations/procedures

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Hazard Control to Mitigate the Hazard PPE Selected

Burns/Injuries from accidental ignition

Engines will be safely stowed in designated box, ignition equipment will be stowed in separate compartments

Long sleeved clothing/Insulated gloves during assembly

Severe injury to eyes Safety goggles are required to be worn when using chemicals or operating power tools

Safety goggles

Hazard Analysis Matrix

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Environmental Safety

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Hazards to Environment Risk Assessment

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Hazard Cause Effect Severity Probability Value-Risk Mitigation

Fire Improper determination of vegetation saturation

Harm to launch site

A 3 A3 - Moderate

Check the launch site conditions prior to launch and locate the nearest fire extinguisher

Trash left behind

Did not patrol our build site

Harm to launch site

C 3 C3 - Low Safety Officer will do a walkthrough of the build site prior to leaving range

Launch Vehicle FMEA

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Failure Mode Cause Effect Severity Probability Value-Risk Mitigation

Transition body structure fails under applied loads during flight

Internal forces exceed the expected limit and the body abruptly separates

Catastrophic failure to the vehicle and potential harm to personnel

A 4 A4 - Moderate

Transition area will be shear tested and validated through full-scale flight tests

Rocket fails to reach required rail exit speed

Mass creep prevents necessary acceleration.

Fail to meet requirement 2.18.

B 3 B3 - Moderate

Procedure in place to weigh parts before and after epoxy application. Simulations will be updated accordingly to ensure compliance

Recovery System FMEA

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Failure Mode Cause Effect Severity Probability Value-Risk Mitigation

Parachute deploys prematurely

Faulty altimeter outputs incorrect altitude.

Descent time significantly increases.Fail to meet requirement 3.10

B 4 B4 - Low A redundant altimeter system will be used per requirement 3.6. Safety officer to review proper installation during pre-flight checklist.

Main Parachute Tangles

Parachute is not properly packed into the body tube

Rocket is not slowed down and may break upon impact

A 3 A3 - Moderate

Parachute will be attached to shock cord with double swivel eye hooks and shock cord will be packed in stacks and taped

Rover Deployment FMEA

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Failure Mode Cause Effect Severity Probability Value-Risk Mitigation

Linear actuator binds

Force applied is not solely 1-directional, causing radial loading

Rover deployment system fails and team fails to meet all 4.3 requirements

A 3 A3 - Moderate

Rover/Deployment system will be vibration tested to ensure 1-directional loading after flight conditions

Linear actuator damages wheel structure

Wheels are incapable of withstanding the force required to break nose cone shear pins

Wheels are immobilized. Team fails to meet requirements 4.3.4 - 4.3.6

A 4 A2 - High Wheels will be designed and tested to the maximum force capability of the linear actuator

Active Retention System (ARS) FMEA

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Failure Mode Cause Effect Severity Probability Value-Risk Mitigation

Retention system stays attached after deployment

Bulkhead connecting wheel to ARS becomes warped

Payload unable to travel 10ft. Team fails to meet requirements 4.3.4 - 4.3.6

A 4 A4 - Moderate

Bulkhead/payload configuration will be tested to the maximum force of the linear actuator to ensure no material damage

Retention system fails during flight

Force of main parachute causes shear pins to break and premature ejection of the payload

Possibility of severe injury. Team fails to meet requirement 4.3.2

A 3 A3 - Moderate

Simulations will estimate the flight forces expected and the ARS will be designed/tested to withstand. Full scale flight test will ensure.

Failure Mode Cause Effect Severity Probability Value-Risk Mitigation

Battery overheats

Rover components overdraw power

Rover cannot collect soil sample. Fails to meet requirements 4.3.4 - 4.3.6

B 3 B3 - Moderate

Payload power breakdown will be created to ensure safe power distribution to all rover components

Rover fails to collect soil

Hole saw is unable to retain the sample collected

Team fails to meet requirements 4.3.5 - 4.3.6

A 3 A3 - Moderate

System will be extensively tested in different soil conditions to verify robustness

Payload FMEA

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Team FinancesFinancial Overview

Budget TimelineRevenuesExpenses

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Financial Overview● $24,000 Overall Funding Goal● $18,000 Funding Procured as of January 10, 2018● $6,000 Funding Committed to Project● $20,690 Current Projected Expenses

■ This number is subject to change

● $2,344.97 Incurred Expenses as of January 10, 2018

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Revenues

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Procured Revenues

Source Amount Procurement Date

UC AIC $6,000 October 23, 2018

Sponsorship $1,000 August 25, 2018

Sponsorship $5,000 November 7, 2018

Sponsorship $1,000 November 28, 2018

OSGC Grant $5,000 December 3, 2018

Total $18,000

Committed Revenues

Source Amount

UC AEEM Department $3,000

CEAS Department of Undergraduate Affairs

$3,000

Total $6,000

Expenses

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Incurred Expenses

Expense Type Amount

NAR Certification Materials $760.45

Subscale Rocket $496.78

Payload Build $578.34

Electronics $509.40

Total: $2,344.97

Projected Total Expenses

Expense Type Amount

Travel $5,600

Rocket $5,700

Electronics $1,000

Payload $2,650

Educational Outreach $250

Certification Materials $990

Overhead $1,280

Management Reserve $3,220

Total: $20,690

Sponsors

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Backup Slides

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Rover Power/Data Flow

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Component Component Mass (g) Quantity Mass of Group (g) Source of info?

6" Wheels 209 2 418 Estimate: V*rho, assumes constant density

Hub bolts 5.15 12 61.8 V*rho

Hub nuts 0.811 12 9.732 V*rho

Hubs 56 2 112 Manufacturer data

Skeleton Threaded Rod 104 4 416 V*rho

Skeleton Nuts 5.3 16 84.8 V*rho

Left Motor Mounting Plate 289 1 289 V*rho

Right Motor Mounting Plate 274 1 274 V*rho

Chassis (collectively) 557 1 557 V*rho, assumes solid print w/ ABS

Drive/Winch Motor 160 3 480 Manufacturer data

Drill Motor 101 1 101 Manufacturer data

Drill Sleeve 38 1 38 V*rho, assumes solid print w/ ABS

Motor Mounting Bracket 13 1 13 V*rho

Gear rack 1.7 1 1.7 V*rho

Pinion gear 3.7 1 3.7 V*rho

Hole Saw 43 1 43 V*rho

Drill Sled 18.2 1 18.2 V*rho, assumes solid print w/ ABS

Sled Spring 1.3 1 1.3 V*rho. NOTE: Needs verified in lab, geometry is scaled, skewing volume measurement

Battery 390 1 390 Manufacturer data

IMU 2.8 1 2.8 Manufacturer data

Motor Driver 7.1 2 14.2 Manufacturer data

Arduino Mega 37 1 37 Manufacturer data

Omni Wheel 22.3 1 22.3 V*rho

Counter-Torque 30.2 1 30.2 V*rho, assumes solid print w/ ABS

Counter-Torque axles 7.7 1 7.7 V*rho

Servo Motors 17 2 34 Manufacturer data

Wires, pins, standoffs, epoxy, etc. 250 1 250 Speculative

Total Mass (g) 3710.432

Torque Arm Servo Positions

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Deployed

Stowed

Drill Sled Servo Positions

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Deployed

Stowed

Drill Sled Servo Positions Bottom View

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Deployed

Stowed