The document discusses how truck simulation tools can enhance the understanding of off/on-road vehicle mobility, focusing on performance-based standards and new powertrain technologies. It highlights the capabilities of simulation in testing various vehicle dynamics such as propulsion, steering, and rollover. Additionally, it mentions advanced powertrain systems like Ford's intelligent 4WD and Toyota's multi-terrain select, which improve vehicle handling in different terrains.

1. 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

2. 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?

3. 3
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

4. 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

5. Examples of Mobility Simulation
Severe Bump Test Course
Rollover Threshold
Tire Forces when Maneuvering

6. 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

7. 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

8. Powertrain Example -- Ford Intelligent 4WD

9. 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

10. 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

11. 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

12. End