Role of subsystem in vehicle
The ‘wheel and axle’ block transmits torque and speed requests from the vehicle block, which represents the tire patch, to the final drive. It also transmits actual torque and speed from the final drive back to the tire patch.
Description of modeling approach
The wheel and axle model includes the effects of losses in the axle bearings, wheel and axle inertia, tire slip, and the action of friction brakes in both the ‘request’ and ‘actual’ data flow paths. Torque losses are handled as a lookup table indexed by vehicle test mass. Tire slip is computed using a lookup table indexed by tractive force. Traction control blocks outside the ‘wheel and axle’ ensure that the tires do not break loose as a result of trying to provide too much force. Brake control blocks outside the ‘wheel and axle’ implement the braking strategy, apportioning required braking force among the driveline, front friction brakes, and rear friction brakes.
Variables used in subsystem
See Appendix A.2: Input Variables
See Appendix A.3: Output Variables
