Thomas D. Gillespie, Ph.D.Research Professor Emeritus, The University of Michigan
Director of Product Planning, Mechanical Simulation Corporation
ISTVS 8th Americas Conference
Simulation Applications in Mobility
Research
Simulation Questions
� In what areas can truck simulation tools help us
understand the mechanics affecting on/off-road mobility?
� Do Performance Based Standards being developed for
on-highway trucks point the way for designing better
off/on-road vehicles?
� What are some of the new technologies for powertrain
control being developed by the automotive industries
that could potentially improve mobility of off/on-road
vehicles?
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Engineering plotter
Surface animator
Vehicle math model solversGraphical database
What Is Simulation?• Computes time-based vehicle motion
• High fidelity models
• All in one, turn key program
• Multiple examples
• Built-in animation
• Built-in plotter
• Runs in real time
Areas where simulation help us understand the mechanics affecting on/off-road mobility?
� Simulation creates a virtual vehicle for testing:
� Mobility/tractive performance – propulsion and braking
� Turning behavior – agility and maneuverability
� Rollover – static and dynamic
� Ride – crew comfort and fatigue
Examples of Mobility Simulation
Severe Bump Test Course
Rollover Threshold
Tire Forces when Maneuvering
Do Performance Based Standards being developed for on-highway trucks point the way for designing better off/on-road vehicles?
� Gradeability and turning quantify maneuvering
performance
� Startability on grades (PBS 15% slopes)
� 10x10 gradeability on slippery terrain
� Front axle friction demand when turning multi-axle
vehicles
New technologies for powertrain control from the automotive industries
� Advanced 4WD/AWD systems
� Broad class of powertrain systems
� Differences between manufacturers, models and brands
� All controls throttle and brakes automatically to increase mobility
� Crawl control
Powertrain Example -- Ford Intelligent 4WD
Ford Intelligent 4WD Features
� Normal: Default FWD with RWD as needed
� Mud/Ruts: Aggressive throttle response, limited
upshifting and de-sensitized ESC to allow more spin
� Snow/Grass/Gravel*: More responsive upshifting
with engine torque controlled for traction
� Sand*: Tuned to allow aggressive wheel spin for
traction
� Hill Descent: Sets and maintains constant speed
during hill descent
*ABS mode changes to allow material build up in front of the tire
Toyota Multi-Terrain Select System with Crawl Control
� Regulates wheel spin by control of throttle and brake
� Crawl Control
� Set speed from 1 – 5 mph
� System controls throttle and brakes, driver only steers
Example of Off-road Simulation
� Crusher is a high-mobility autonomous vehicle
� Developed by National Robotics Engineering Center, Pittsburgh PA
� 6x6 vehicle with skid steer
� Advanced high speed model was tested using TruckSim
Ref: DARPA Project, Carnegie Mellon University
National Robotics Engineering Center
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