Vehicle control with method of permitting limited wheel slip

摘要

A control means 140, for controlling motion of a vehicle 100 over a surface, the control means 140 being operable to limit an amount of drive torque that may be applied to one or more wheels of the vehicle so as to prevent an amount of wheel slip from exceeding a prescribed value. Wheel slip is defined as a ratio of wheel speed to ground speed. The controller 140 is operable to permit an amount of wheel slip in order to achieve a maximum tractive force or exceed a corresponding drive torque by a prescribed proportion. Control is achievable by braking or by controlling an electric motor 111M-114M) provided at each wheel 111-114 so that the wheels 111-114 are driven at a prescribed torque value to prevent the amount of wheel slip from exceeding a prescribed value which is determined in dependence at least in part on vehicle speed.