Wheel slip control via second order sliding modes generation

During skid-braking and spin-acceleration, the driving force exerted by the tires reduces considerably and the vehicle cannot speed up or brake as desired. It may become very difficult to control the vehicle under these conditions. To solve this problem, a second order sliding mode traction controller for road vehicles is presented in this paper. The traction control is achieved by maintaining the wheels slip at the optimal value. In this way, the traction control enables anti-skid braking and anti^spin acceleration, thus improving safety in difficult weather conditions, as well as stability during high performance driving. The choice of the control methodology adopted in this paper is motivated by its robustness feature with respect to parameter uncertainties and disturbances which are typical of the automotive context. Moreover, the proposed second order sliding mode controller, in contrast to conventional sliding mode controllers, generates continuous control actions, thus resulting particularly suitable to be applied to automotive systems, where vibrations limitation is a crucial requirement.