A Stability Guaranteed Robust Fault Tolerant Control Design for Vehicle Suspension Systems Subject to Actuator Faults and Disturbances

A fault tolerant control approach based on a novel sliding mode method is proposed in this brief for a full vehicle suspension system. The proposed approach aims at retaining system stability in the presence of model uncertainties, actuator faults, parameter variations, and neglected nonlinear effects. The design is based on a realistic model that includes road uncertainties, disturbances, and faults. The design begins by dividing the system into two subsystems: a first subsystem with 3 degrees-of-freedom (DoF) representing the chassis and a second subsystem with 4 DoF representing the wheels, electrohydraulic actuators, and effect of road disturbances and actuator faults. Based on the analysis of the system performance, the first subsystem is considered as the internal dynamic of the whole system for control design purposes. The proposed algorithm is implemented in two stages to provide a stability guaranteed approach. A robust optimal sliding mode controller is designed first for the uncertain internal dynamics of the system to mitigate the effect of road disturbances. Then, a robust sliding mode controller is proposed to handle actuator faults and ensure overall stability of the whole system. The proposed approach has been tested on a 7-DoF full car model subject to uncertainties and actuator faults. The results are compared with the ones obtained using H_∞ approach. The proposed approach optimizes riding comfort and road holding ability even in the presence of actuator faults and parameter variations.