VITL Preliminary Design Review (PDR)

VITL April 20, 2023

VITLPreliminary

Design Review (PDR)

Thursday, April 20, 2023

Team Members: Ryan Hickman, Chris Homolac, Jen Krupp, Kyle Ligon,

Heather Love, Alex Paulson, Kathryn Rash, Veronica Vertucci

Vehicle for Icy Terrain Locomotion2

VITL April 20, 2023

Overview

• Project Objectives Overview• System Design Alternatives• System Design-To Specifications• Subsystem Design Alternatives & Feasibility

– Drive System– Sensors & Software– Command & Data Handling (C&DH)– Structure– Power– Thermal

• Testing Analysis• Risk Assessment• Project Management Plan


VITL April 20, 2023

Overview





VITL April 20, 2023

Objectives & Goals Overview

• Design and build a prototype for the locomotion system of a vehicle exploring Europa– Capable of traversing 1 km of icy

terrain in 7 days– Capable of traversing obstacles

characteristic of Europa

• Maximize traversable incline• Maximize range• Minimize power draw and

mass


VITL April 20, 2023

Objectives Overview

• Why Europa?– One of the best candidates for life beyond earth– Under Europa’s surface (~100m) is the most likely location for liquid water outside of Earth

• Technological Challenges– Europa’s surface temperature is about 100K– Power– Radiation– Traction – 1/6 Earth gravity


VITL April 20, 2023

Overview

• Project Objectives Overview• System Design Alternatives• System Design-To Specifications• Subsystem Design Alternatives




VITL April 20, 2023

System Design Alternatives

•Wheeled•Spider•UAV

•Snake•Roller•Tracked


VITL April 20, 2023

System Design Alternatives

• Performance Variables– Experience– Power– Thermal– Traction– Speed– Stability– Complexity– Agility– Mass– Structure– Payload

• Initial Calculations• Trade Study Weighting• Top Level Feasibility

Wheeled Architecture3, 4 and 6 Wheeled

designsAdditional Trades

6 Wheeled Design


VITL April 20, 2023

Overview





VITL April 20, 2023

System Design To Specifications

VITL

Structural 1.0 Electronics 2.0 Performance 3.0

Geometry 1.1

Payload Considerations 1.2

Terrain Crossing 3.1

Inclination 3.2

Direction Change 3.3

Autonomy 2.1

Control 2.2

Mission Life 2.3

Temperature 3.4

Range 3.5

Efficiency/Accuracy 3.6


VITL April 20, 2023

Design To Specifications

• Traction and Maneuverability– Six wheels to grip icy terrain– Sufficient traction for accurate navigation

• Autonomy– Sensors to detect hazardous terrain– Navigate unpredictable terrain

• Survivability– Substantially built – Insulated to survive at cryogenic temperatures– Last seven days – Travel one kilometer

• Payload attachment


VITL April 20, 2023

Overview





VITL April 20, 2023

Drive System


VITL April 20, 2023

Drive: Design To Specifications

• Geometry– Maximum Size of vehicle: 1 m3

• Terrain Crossing– Ice at 100 K– Ruts & Ridges: 1 m x 8 cm x 3 cm (L x W x

H)– Inclination: 20°

• Capabilities– Zero turning radius– Range: 1 km in 7 Earth days


VITL April 20, 2023

Drive: Design Components

Drive System Components

Drivetrain Wheels Motors

Type

Suspension

Type Location

Number

Material

Size

Type

Turning

MaterialCapability


VITL April 20, 2023

Drive: Drivetrain Alternatives

Chain or Belt Drive

Shaft Drive Direct Drive

Pros Moderate MassLow No. Motors

Moderate ComplexityAdequate Wheel Speed Control

High Efficiency (~94%)

Low No. MotorsHigh Reliability

Good Wheel Speed Control

High Efficiency (~99%)

High ReliabilityLow Complexity

Low Mass

Cons Low Efficiency (~75-97%)

Low ReliabilityChains & Belts

High MassHigh Complexity

High No. MotorsPoor Wheel Speed

Control


VITL April 20, 2023

Drive: Wheel Alternatives

Design A B C D

Stability 2 1 4 4

Complexity 4 3 2 1

Reliability 2 1 4 3

Feasibility 4 4 4 4

Overall 12 9 14 12

• Location & Number

1 – Poor/Unsatisfactory

2 – Good/Average 3 – Better/Exceptional

4 – Best/Excellent

Design 1 Design 2 Design 3 Design 4


VITL April 20, 2023

Wheel Design Alternatives

• Size

D

h Fτ

W

D FNMotor

N

N

F

NoW

No

FWmaxmax 2

2cmDhD 62


VITL April 20, 2023

Drive: Motor Alternatives

Brush D.C. Motor

Brushless D.C. Motor

A.C. Induction Motor

Stepper Motor

Pros High Torque @ Low RPM

Low costSimple

High Torque @ High RPM

Long LifeHigh EfficiencyGood Vacuum

QualitiesLarge Speed Range

High Torque @ High RPM

High Reliability

High Precision Actuation

Cons

Limited LifeLimited Speed Range

Poor Vacuum Qualities

Low EfficiencyEMF

High costHigh Complexity

Limited LifeLimited Speed Range

Poor Vacuum Qualities

Low Efficiency

Low TorqueLimited Speed Range

High ComplexityEMF

NASA Report “Selection of Electric Motors for Aerospace Applications”

• Type


VITL April 20, 2023

Drive: Suspension Alternatives

Fixed Rocker-Bogie

Complexity 2 1

Obstacle Clearance 1 2

Efficiency 1 2

Mass 2 2

Feasibility 2 2

Overall 8 9

• Type

1 – Poor/Unsatisfactory 2 – Best/Excellent


VITL April 20, 2023

Suspension Design Alternatives

Design A B C

Maneuverability 1 3 3

Complexity 2 1 3

Efficiency 2 3 1

Speed 1 3 2

Feasibility 3 3 3

Overall 9 13 12

• Turning

1 – Poor/Unsatisfactory

2 – Good/Average 3 – Best/Excellent

Design A Design B Design C


VITL April 20, 2023

Sensors

• Design-to-Specifications– Slope

• Vehicle shall not exceed a slope of 20°

– Obstacles• Vehicle shall detect obstacles that are larger than 1”

as defined by customer

– Cliff• Vehicle must be able to detect if a cliff, wall, or slope

larger 20° is in its current path

– Distance • Vehicle shall travel 100 m and be accurate to that

distance within one vehicle body length


VITL April 20, 2023

Sensors

Sensors

Slope Obstacles Cliff

Upcoming Current Proximity Sensor

Range Finder

Mechanical Arm

Accelerometer

2-axis

3-axis

Infrared

Laser

Pressure Sensor

Infrared

Laser

Stereo Camera

Range Finder Mechanical Arm

Infrared

Laser

Pressure Sensor


VITL April 20, 2023

C&DH/Comm Design Alternatives

C&DH

CPU Control Method Data Storage

PIC / AVR

Brainstem

BASIC Stamp

FPGA

RF Control

Pre-Programmable

Motor Control

On-board Memory

Telemetered

H-Bridge

Custom BuiltIntegrated w/

Microcontroller

External Memory

Modules


VITL April 20, 2023

C&DH: CPU Alternatives

• Criteria– Easily programmable– Fair price

• Must be able to afford back up CPUs

– Supports enough ADC for all analog inputs

• If not, ability to add external ADCs or have two controllers working together


VITL April 20, 2023

Structures

• Overview– Primary requirements

• Volume less than 1 m3

• Survival at 100 K• Payload Considerations (<10 kg)

– Flowdown requirements• Structural stability• Structure/drivetrain interactions• Support for subsystems (structural and wiring)• Maximum load sustained


VITL April 20, 2023

Structures

• Fundamental Design Alternatives– Primary structure layout

• Box• Circular

– Subsystem boxes• Shell• Wire frame

– Drivetrain interface• Integration into design• Modular

– Wiring support• Common bus• Distributed network


VITL April 20, 2023

Structures

• Primary Structure Layout AlternativesCircular Box

-Minimize stress points -Conventional Design-Complex drivetrain interaction, stability -Straightforward

drivetrain-Good for agility, common data/power -Strength may be an

issue


VITL April 20, 2023

Structural Feasibility


VITL April 20, 2023

Power

• Design To Specifications– Wattage/Voltage

• Provide enough wattage and voltage to run all components needed for testing

– Capacity• Provide a long enough run-time to verify the

requirements for the tests


VITL April 20, 2023

Power

• Not a requirement for prototype but is still considered

• Needed for testing purposes• Actual Rover

– RTG’s - but these may cause contamination– Future technological advancements

• Prototype– Batteries: Lithium Ion

• Wide range of operating temperatures• High capacity• Rechargeable


VITL April 20, 2023

Thermal

• Design To Specifications– Thermal Vac

• Provide the system with enough heat where needed to function properly at 100K

– Other tests• Keep the ambient temperature of each of the

components within operating temperatures


VITL April 20, 2023

Thermal

• Need to keep all internal components -20°C or above for prototype– Due to operating temperatures

of most components• Actual Rover

– Need heaters on all servos• Due to the specifications of the

material used• Can use RHU’s

– Aerogel Insulation• Prototype

– Fiberglass insulation– Aerogel for thermal vacuum

testing


VITL April 20, 2023

Overview





VITL April 20, 2023

Testing: Verification of RequirementsTesting

Drive Assembly in

100K Thermal VacuumTerrain Course Straight, Level Course

Operation at 100 K Autonomy •Efficiency/Accuracy

Terrain Crossing

Inclination

Direction Change

Mission Life

Range

RC Control

Total Vehicle or

Drive Assembly

in 200 K Thermal Vacuum

100 K Ice Surface Interaction

With Wheel Modification

100 K Ice Surface Interaction

With Wheel Modification


VITL April 20, 2023

Testing: NeedsOverall Test

Drive Assembly in

100K Thermal VacuumTerrain Course Straight, Level Course

Facility

Sensors

Surface Material to Simulate Europa

Surface and Wheel Interactions

Structure with Variable Incline

Surface Material to Simulate Europa

Surface and Wheel Interactions

Location Measurement Device

Support Apparatus Observation Method

Reliable On-board

Distance Sensors

Structure Verification

and Direction Change Devices

Timer

Timer

Obstacles


VITL April 20, 2023

Testing: Terrain Course


VITL April 20, 2023

Testing: Out of Prototype Scope

• Design– Power Source

• Testing– Europa Environment

• Radiation• Pressure• Total vehicle at 100 K


VITL April 20, 2023

Overview





VITL April 20, 2023

Top Risks Assessment

2 1 4

5

3

Con

sequ

ence

Probability

(1) Motor/Electronics Failure at 100K

Use cryogenic motors/electronics

Add heaters

(2) Localized Stress Concentrations

Design with large stress margins

(3) Schedule Delays

Overestimate time by at least 2x

(4) Cost Overruns

Apply for UROP/EEF

Maximize existing facilities and resources

(5) Availability of Testing Facilities

Backup thermal tests at lower temp.


VITL April 20, 2023

Risk Assessment: Prototyping

• Component boxes to represent subsystem loads and distributions

• Motor testing in thermal vacuum (if available)

• Possible materials testing in thermal vacuum (if available)


VITL April 20, 2023

Overview





VITL April 20, 2023

Organizational ResponsibilitiesProject Manager: Veronica Vertucci

Systems Engineer: Kyle Ligon

Managerial Roles

Assistant PM: Heather Love

Fabrication: Ryan Hickman

Fabrication: Alex Paulson

CFO: Kathryn Rash

Safety Engineer: Jen Krupp

Webmaster: Chris Homolac

Technical Leads

Drive Mechanics: Ryan Hickman

Structures: Alex Paulson

C&DH: Chris Homolac

Sensors: Jen Krupp

Thermal/Power: Heather Love

Testing: Kathryn Rash


VITL April 20, 2023

Work Breakdown Structure (WBS)

VITL

Drive C&DH Power ThermalStructures Testing

Drive Train

Motors

Suspension

Wheels

Sensors Software

CPU

Storage

Motor Control

Remote

RF TX/RX

Frame

Connectors

Cables

Battery

Charger

100K Heater

Insulation

100K

Terrain

Straight/Level

Acceler.

Odometer

Rate Gyro

Autonomy

Locomotion

Range Boxes

100K Insul.


VITL April 20, 2023

PDR-CDR Schedule

ID Task Name Duration Start Finish

1 Prototype Shipping 3 wks Wed 10/18/06 Tue 11/7/062 Assignment #6 due 0 days Thu 11/2/06 Thu 11/2/063 Assignment #7 due 0 days Thu 11/16/06 Thu 11/16/064 Systems Integration 1 wk Mon 11/6/06 Fri 11/10/065 Slides 2 wks Mon 11/13/06 Fri 11/24/066 Margin 1 wk Mon 11/27/06 Fri 12/1/067 CDR 0 days Mon 12/4/06 Mon 12/4/068 Drive System 20 days Mon 10/23/06 Fri 11/17/069 Prototyping 3 days Wed 11/8/06 Fri 11/10/0610 Final Design 4 wks Mon 10/23/06 Fri 11/17/0611 Structures 20 days Mon 10/23/06 Fri 11/17/0612 Prototyping 1 day Wed 11/8/06 Wed 11/8/0613 Final Design 4 wks Mon 10/23/06 Fri 11/17/0614 Sensors 3 days Thu 11/9/06 Mon 11/13/0615 Testing 3 days Thu 11/9/06 Mon 11/13/0616 Algorithms 10 days Mon 10/30/06 Fri 11/10/0617 Autonomy 1 wk Mon 10/30/06 Fri 11/3/0618 Locomotion 1 wk Mon 11/6/06 Fri 11/10/0619 C&DH/COMM 15 days Mon 10/23/06 Fri 11/10/0620 Final Design 3 wks Mon 10/23/06 Fri 11/10/06

Shipping

11/2 Assignment #6 due

11/16 Assignment #7 due

Systems Integration

Slides

Margin

12/4 CDR

Drive System

Prototyping

Final Design

Structures

Prototyping

Final Design

Sensors

Testing

Algorithms

Autonomy

Locomotion

C&DH/COMM

Final Design

10/1 10/8 10/15 10/22 10/29 11/5 11/12 11/19 11/26 12/3 12/10October November December


VITL April 20, 2023

Spring Semester Schedule

ID Task Name

1 Drive Subsystem

2 Sensors & Software

3 C&DH/COMM

4 Structures

5 Power

6 Thermal

7 Testing

8 CDR

9 Fall Final Report

10 Spring Review 1

11 Spring Review 2

12 Last Machining Day

13 Final Review

14 Design Expo

15 Spring Final Report

16 Margin

17 Slides

18 Final Report

19 Poster

Drive Subsystem

Sensors & Software

C&DH/COMM

Structures

Power

Thermal

Testing

12/4

12/18

1/29

2/26

3/16

4/17

4/28

5/3

Margin

Slides

Final Report

Poster

12/3 12/10 12/17 12/24 12/31 1/7 1/14 1/21 1/28 2/4 2/11 2/18 2/25 3/4 3/11 3/18 3/25 4/1 4/8 4/15 4/22 4/29 5/6 5/13 5/20December January February March April May


VITL April 20, 2023

Cost Estimates Number Cost

Drive Subsystem $1,040

Drive Train 0 $0

Wheels 6 $175

Motors 7 $840

Suspension 1 $25

Sensors & Software $417

Accelerometer 1 $12

Odometer 4 $75

Rate Gyro 1 $30

Radar/IR/Laser 2 $300

Autonomy Algorithm 1 $0

Locomotion Algorithm 1 $0

C&DH/COMM $290

CPU 1 $50

Data Storage 1 $10

Motor Control/Misc 1 $150

Remote Controller 1 $50

RF TX 1 $15

RF RX 1 $15

Number Cost

Structures $670

Frame 1 $500

Connecters 20 $50

Cables 10 $20

Component boxes 4 $100

Power $84

Battery 3 $34

Battery Charger 1 $50

Thermal $177

Heater for 100K 1 $40

Insulation 1 $7

Insulation for testing100K 1 $130

Testing $1,205

100 K $910

Structure 1 $30

Torquemeter 1 $800

Voltmeter 1 $0

Ammeter 1 $0

Rotary sensor (optional) 1 $80

Number Cost

Thermal Vacuum 1 $0

Terrain Course $255

Obstacles - Boxes 3 $5

Surface Material - Wood 4 $160

Structure - Wood 10 $90

Observation 1 $0

Timer - Stop Watch 1 $0

Straight/Level Course $40

Distance Sensor 1 $40

Shipping $300

Management Costs $250

Subtotal $4,433

35% Margin $1,551

Total $5,985

• Will require additional funding from EEF/UROP grants


VITL April 20, 2023

Limited Budget

Cost

Drive Subsystem $1,000

Sensors & Software $400

C&DH/COMM $290

Structures $500

Power $84

Thermal $150

Testing $800

Shipping $250

Management Costs $150

Subtotal $3,624

10% Margin $362.40

Total $3,986

• Still possible without EEF/UROP funding

• Requires substantial decrease in Testing and Structures and minor cuts in the remaining subsystems


VITL April 20, 2023

Specialized Facilities and Resources

• Ball Thermal Vacuum• University of Colorado Ice Rink• Lake


VITL April 20, 2023

Acronym List

• ADC: Analog to Digital Converter• C&DH: Command and Data Handling• COTS: Commercial Off The Shelf• CPU: Central Processing Unit• RF: Radio Frequency• RHU: Radioisotope Heater Unit• RTG: Radioisotope Thermoelectric Generator• RX: Receiver• TX: Transmitter• WBS: Work Breakdown Structure


VITL April 20, 2023

References

• Trudy Schwartz• SolidWorks 2005• Vable, Madhukar. Mechanics of Materials.• www.onlinemetals.com• www.matweb.com• www.analog.com• www.pcb.com• www.thomasnet.com• www.globalspec.com• www.servosystems.com• www.sensotech.com• www.omega.com• www.powerelectrics.co.uk• www.quadratureencoders.com• www.panasonic.com• www.powerstream.com• www.all-battery.com• www.media.popularmechanics.com• www.maxon.com• www.nasa.gov


VITL April 20, 2023

Additional Slides


VITL April 20, 2023

1.1 : Geometry Requirement:

Entire vehicle must fit within 1 m3.

1.1.1 : No component shall be larger than

1 m3 or longer than m.

1.1.2 : Wheel diameter cannot exceed 1/3

meters in order for wheel not to collide.

3

1 m

1/6m

1.1 Geometry Requirement


VITL April 20, 2023

1.2 : Payload Considerations

1.2.1 : Payload placed to position CG appropriately.

1.2.2 : Payload located such that it does not interfere with other sub systems and is adequately heated.

1.2 Payload Considerations


VITL April 20, 2023

Drive System Demonstration


VITL April 20, 2023



VITL April 20, 2023

Drive: Wheel Alternatives• Moment of Inertia Calculations

2,,

22,,

2

1

4

1

12

1

wzwcm

wxwcm

mrI

rwmI

22,,,

2,,,

44

44

xwzwcmzCM

zxwcmxCM

drII

ddwII

22,,,

2,,,

24

24

xwzwcmzCM

zxwcmxCM

drII

ddwII

22,,,

2,,,

46

66

xwzwcmzCM

zxwcmxCM

drII

ddwII

22

222,,,

2,,,

246

66

xwxwzwcmzCM

zxwcmxCM

drdrII

ddwII

2xx dd

4,,,3,,,2,,,1,,, ywcmywcmywcmywcm IIII

Design 1 Design 2 Design 3 Design 4

x

z

x

z

x

z

x

z


VITL April 20, 2023

Drive: Wheel Alternatives

• Material304 Stainless

SteelINVAR 32-5 Titanium Aluminum

7075 – T6

Density (g/cm3) 8 8.14 4.5 2.81

Yield Strength (MPa)

215 276 140 503

Tensile Strength

(MPa)

505 483 220 572

CTE (μm/m-°C)

17.3 0.63 8.9 23.6

Rockwell B Hardness

70 90 ~40 87

Cost ($/cm3) ~0.15 ~0.34 ~4.33 ~0.10


VITL April 20, 2023


• EC Brushless DC Motors– COTS operational temps:

-35°C to +100°C– Heritage operational

temps: -120°C to +25°C

)sin(

,

ninclinatioEuropavehiclewheelsmotor

slopefwheelsmotor

gmr

Fr

• Torque


VITL April 20, 2023

Drive: Suspension Alternatives

• Material304 Stainless

SteelINVAR 32-5 Titanium Aluminum

7075 – T6

Density (g/cm3) 8 8.14 4.5 2.81

Yield Strength (MPa)

215 276 140 503

Tensile Strength

(MPa)

505 483 220 572

CTE (μm/m-°C)

17.3 0.63 8.9 23.6

Rockwell B Hardness

70 90 ~40 87

Cost ($/cm3) ~0.15 ~0.34 ~4.33 ~0.10


VITL April 20, 2023

Drive: Mass and Cost Budgets

Mass & Margin Cost & Margin

Drivetrain 0.00 0.00

Motor 1.50 kg 50 % $720.00 50 %

Wheels 1.38 kg 25% $175.00 25%

Suspension

0.60 kg 200% $25.00 25%

Total 7.43 920.00


VITL April 20, 2023

Design System Calculations

• Coefficient of FrictionEuropatotalw gmF

)cos()cos( inclineEuropatotalinclinewN gmFF

)sin()sin( inclineEuropatotalinclinewslide gmFF

sinclineEuropatotalsNsf FgmFF )cos(

)tan()sin(

)cos(incline

inclineEuropatotal

inclineEuropatotal

f

ss gm

gm

F

F

)tan( inclines

– μs = 0.36397

φincline

Fslip

FfFw

FN


VITL April 20, 2023

Drive: System Calculations

• Equivalent Earth Inclination

h

wroll 2

tan 1

θroll

w

h

)sin( ,inclineEuropatotalwheelfwheelEuropa gmrFr

EarthEuropa

)sin()sin( ,, EarthinclineEarthtotalwheelEuropainclineEuropatotalwheel gmrgmr

)sin(sin ,

1, Europaincline

Earth

EuropaEarthincline g

g

• Rollover Angle

φinclination,Earth = 2.62°


VITL April 20, 2023

Typical Sensor Specifications

Part Type Op. Temperature Mass Supply PowerAccelerometer www.analog.com

ADXL312 2-axis -40 to 185 ºC < 1.0 g 5 V < 0.5 WADXL330 3-axis -25 to 70 ºC < 1.0 g 5 V < 0.5 W

Rate Gyro www.analog.comADXRS150 ± 150 °/s -40 to 85 ºC < 0.5 g 5 V < 0.5 WADXRS300 ± 300 º/s -40 to 85 ºC < 0.5 g 5 V < 0.5 WADXRS401 ± 75 º/s -40 to 85 ºC < 0.5 g 5 V < 0.5 W

Laser Range www.powelectrics.co.ukLDS 100/700 400-1100 mm 0 to 45 ºC 1600 g 24 VDC 4.5 WLDS 100/1400 700-2100 mm 0 to 45 ºC 3600 g 24 VDC 4.5 WLDS 100/2000 2000-4000 mm 0 to 45 ºC 3600 g 24 VDC 4.5 W

Odometer www.quadratureencoders.comE2 .394 in -40 to 100 ºC 40 g 5 V < 0.5 WE3 1.0 in -40 to 100 ºC 40 g 5 V < 0.5 W

E6MD 1.0 in -40 to 100 ºC 60 g 5 V < 0.5 W


VITL April 20, 2023

Sensors: Range

• Odometry– Straight

• Incremental• Phase

– Turning• Rate Gyro• Accelerometer


VITL April 20, 2023

Autonomy

Matlab C/C++

Pros More ExperienceMore Powerful

SimpleLight weightEasy Integration

Cons Processor Intensive Not as powerfulNot as experienced


VITL April 20, 2023

C&DH: Control Alternatives

• Criteria– Creates easy testing

environment– Maintains simple design

(not overly complex to implement)

• Control Methods– Radio Frequency (RF)

• Requires Comm subsystem with receiver/transmitter equipment

• Remote Control

– Programmable• Pre-programmed

software modules• Programs must be

quickly and easily changeable for testing (Might require laptop)


VITL April 20, 2023

C&DH: Data Storage Alternatives

• Onboard Memory– Memory embedded

within CPU• Might lower resolution

of data

– External Memory modules connected to CPU

• More complex to integrate

• Offers large data storage

• Telemetered Data– Requires Comm

subsystem– Requires high baud rate

to telemeter data back to external memory

– Requires external memory not a part of main system (Might require laptop)


VITL April 20, 2023

C&DH: Motor Control Alternatives

• Criteria– Easy to implement– Fair price

• Must be able to reproduce easily or buy spares

• H-Bridge– Tailored to specific

designs– Might not be compatible

with type of rover design

• Self-Constructed– Requires more

electronic configuration– Adaptable to any rover

design


VITL April 20, 2023

Structures


VITL April 20, 2023

Structures

• Initial Material Assessment– Rough comparisons of materials commonly used in

cryogenic applications– Steps:

Cost is of that of 12x12x.1 inch or similar sized plate

Y

FA

A

F

min

Alengthunit

mass

Materialksi lb/in3

Specific Strength( / )

Amin (in2)X10-

4

m/L lb/in(x10-

4)

Cost($)

AISI 304steel

39 0.289 134.94 28 8.1 36

Ti 5-Al 2.5-Sn

115 0.162 709.8 9.6 1.5 1,021

INVAR 40 0.291 137.45 28 8.0 80

Aluminum 7075

21 0.097 215.38 50 5.1 23

Y Y


VITL April 20, 2023

Structures

• Initial Feasibility Assessment– SolidWorks with dimensions of available

materials– 50 kg load at center, edges fixed, determine if

any points exceed yield strength of material– Shows that some Aluminum configurations

would not be feasible, though most would, as would most configurations of other materials


VITL April 20, 2023

Power

• Component Trade StudyComponent Cost

Accessibility

Added Mass to Vehicle

Usability

RTG High Poor Low Medium

Power Supply Medium Good None High

Batteries Low Good High High

Electrical Outlet

Very Low Good None Low


VITL April 20, 2023

Power

• Battery Trade Study

BatteryMass(g)

Operating Temperatu

re

Capacity

(mAh)

Primary/ Secondar

yCost

Lithium Thionyl Chloride Multi-

Cell40

-40°C to 60°C

1000 Primary $5.40

Manganese Dioxide Lithium

35-40°C to

60°C1300 Primary $5.95

Lithium Thionyl Chloride

40-40°C to

60°C1000 Primary $5.95

Primary Lithium Thionyl Chloride

190-55°C to

85°C36000 Primary $34.95

Lithium Ion 47-60°C to

40°C2350 Secondary $7.85


VITL April 20, 2023

Thermal

• Component Trade StudyComponent Cost

Accessibility

Added Mass to Vehicle

Usability

Aerogel Insulation

High Low Low Medium

Other Insulation (Fiberglass

etc.)

Low High Medium High

Heaters Medium Medium High Medium


VITL April 20, 2023

Testing: 100K Thermal Vacuum

• Facility Resources– Ball Aerospace– Advanced Product

Testing

• Sensors to measure– Torque– Voltage– Current– Wheel and Axle Rotation

• Supporting Apparatus– Same material as

suspension


VITL April 20, 2023

Testing: Terrain Course Characteristics

• Odometers to measure distance traveled

• Defined box/grid to measure direction change

• Camera to document success or failure to maneuver as expected

• Timer to record test duration

• Potential surface materials– Wood– Plastic– Metals

• Dangerous Obstacles– Cardboard boxes

• Variable Inclines– Notched vertical

supports– Vertical supports of

varying height


VITL April 20, 2023

Testing: Straight and Level Course

• Potential surface materials– Wood– Plastic– Metals– Ice

• Arena• Lake

• On-board sensors to measure distance traveled

• Timer to record test duration

• Location Measurement– GPS– Surveying equipment– Reel Tape Measure– Accuracy need depends

on length of course

Documents

VITL Preliminary Design Review (PDR)