Tracking and Regulation Control of a Skid Steering Vehicle

Differentially driven skid-steering vehicles are often considered for navigation in outdoor terrains. However, the control of such vehicles is challenging because the wheels must skid laterally to follow a curved path, and motion stability can be lost as a result of excess skidding due to the position of the instantaneous center of rotation (ICR). To accommodate for the potential loss of stability due to the ICR, the development in this paper places an artificial operational nonholonomic constraint on the vehicle motion. Based on the operational constraint, a robust nonlinear controller is presented that can be used to achieve unified tracking and regulation of the vehicle. The dynamic model of the vehicle is also considered to incorporate further robustness to disturbances such as unknown vehicle properties and ground interaction forces.