Sliding mode measurement feedback control for antilock braking systems

We describe a nonlinear observer-based design for control of vehicle tracti on that is important in providing safety and obtaining desired longitudinal vehicle motion. First, a robust sliding mode controller is designed to mai ntain the wheel slip at any given value. Simulations show that longitudinal traction controller is capable of controlling the vehicle with parameter d eviations and disturbances, The direct state feedback is then replaced with nonlinear observers to estimate the vehicle velocity from the output of th e system (i.e., wheel velocity). The nonlinear model of the system is shown locally observable. The effects and drawbacks of the extended Kalman filte rs and sliding observers are shown via simulations. The sliding observer is found promising while the extended Kalman filter is unsatisfactory due to unpredictable changes in the road conditions.