Colloquia

Summary

Skid steering a steering method that is used by some types of UGV's. Turning the wheels on either the left or right side of the vehicle at different speeds results in turning of the vehicle around its vertical axis. The real-time dynamic simulation of the dynamics of UGV's that employ skid steering is the main objective of this work. To accurately simulate skid steering an appropriate set of equations of motion should be in place, as well as a wheel friction model that accurately models the longitudinal and lateral friction forces on the wheel. First a set of equations of motion is derived using minimal coordinates that describe the dynamics of a UGV. Multiple wheel friction models are presented that model the forces of a wheel given the linear and angular velocities of the wheel. This includes a new switching damper model. The various wheel models are validated by comparing the dynamics that result from the models, to measured dynamics. The measured dynamics are obtained from several physical driving tests. The switching damper model most accurately simulates skid steering wheel friction and it is validated in multiple skidding and driving cases. Simulation speed is found to depend heavily on the integration method used for which implicit integration is recommended.