scale model automated road vehicle
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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
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