An optimal robust controller for active trailer differential braking systems of car-trailer combinations

This paper presents an optimal robust controller for active trailer differential braking (ATDB) systems of car-trailer (CT) combinations. To design ATDB systems, controllers based on the linear quadratic regulator (LQR) technique have been explored. In these LQR controller designs, vehicle forward speed, trailer payload, etc., were assumed as constants. In reality, a CT combination is frequently confronted with variations of operating conditions and vehicle parameters, which may impose significant impacts on the lateral stability of these vehicles. This motivates the investigation into robust controller designs. An ATDB controller is designed using the µ synthesis technique. A new method using a genetic algorithm (GA) for tuning the weighting function parameters for the robust controller is presented. In the parameters tuning process, the lateral stability is emphasised and the path-following capability is considered. Simulation results confirm the validity of the ATDB controller.