Scale Model Automated Road Vehicle Advanced Transit Association Annual Technical Meeting January 10,...

Scale Model Automated Road Vehicle

Advanced Transit Association Annual Technical Meeting

January 10, 2010

College Park, Maryland

Robert Johnson

R. E. Johnson ConsultingRockville, Maryland

www.REJConsult.com

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Examples ofSmall Automated Road Vehicles

CyberCab: proposed by 2getthere which developed the first public automated road vehicle (ParkShuttle)

ULTra: scheduled to begin service in 2010 at Heathrow airport, London

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Alternative Interior Layouts and Service Concepts

Typical PRT– Two fixed seats– Two fold-down seats

– Could have pure PRT or some sharing

“Automated Microbus”– Four fixed seats– Two fold-down seats– More suitable for

shared operation

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Choice of Scale

• Want smallest possible vehicle to allow small infrastructure

• Want vehicle big enough to hold useful electronics

• Popular Mini-ITX computer board is 6.7 x 6.7 in. (17 x17 cm)

• Full-sized vehicle will be higher than it’s wide, so height is critical dimension

Choice of Scale (cont.)

• An 8 in. (20 cm) high model would hold Mini-ITX board with 1.3 in (3 cm) allowance for ground clearance and vehicle structure

• Assuming full-sized vehicle is 72 in (183 cm) high, this gives a scale of 8/72 = 1/9

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Why Not Modify Radio Controlled Car?

• R/C car over ten times as fast as needed

• Front track to wheelbase ratio – R/C cars are typically wide for stability

• Custom built model can provide flexible interior space

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Aspects of Vehicle that are Realistically Modeled

• Length, width, height

• Wheelbase, front track

• Ackermann steering – inside front wheel angled more sharply in turns

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Aspects Not Realistically Modeled

• One central rear wheel instead of two wheels and differential

• No suspension – only operates on smooth, level surface

• Motor braking only (will add brake if necessary)

• No power doors or other passenger-related systems

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Initial Hardware Choices

• Mainboard – Intel D945GSEJT with 1 GB ram and 2 GB solid state hard disk

• Low-level microcontroller – Atmel AVR 8-bit microprocessor packaged on small board with motor driver chip by www.pololu.com (Item 1220)

• Steering – standard “radio controlled” servo

• Drive motor – standard DC gearmotor

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For more information about (full size) Automated Road Vehicles, please see:

www.AutoRoadVehicles.com