Adaptive Optimizing Dynamic Control Allocation Algorithm for Yaw Stabilization of an Automotive Vehicle using Brakes

In this paper we present a yaw stabilization scheme for an automotive vehicle, that has been implemented in a realistic nonlinear multi body vehicle simulation environment. The stabilization strategy is based on two modules independent in design, a high level module that deals with the motion control objective and a low level module that deals with the actuator control allocation. The high level module consists of yaw-rate reference generator and high level controller that provides the low level control allocation module with a desired torque about the yaw axis. The task of the low level module is to command the individual brakes, the longitudinal clamping force, such that the actual torque about the yaw axis tends to the desired torque. These commands are generated by a dynamic control allocation algorithm that also takes actuator constraints and uncertainty in the tyre-road friction model into consideration. Simulation cases where the tyre-road friction parameter was considered both known and unknown, show that the control scheme stabilizes the vehicle in extreme manoeuvres where the nonlinear vehicle yaw dynamics otherwise becomes unstable in the sense of over or under-steering.