Adaptive PID-Sliding-Mode Fault-Tolerant Control Approach for Vehicle Suspension Systems Subject to Actuator Faults

Advanced fault-tolerant control schemes are required for ensuring efficient and reliable operation of complex technological systems such as ground vehicles. A novel approach to fault-tolerant control design is proposed for a full-scale vehicle dynamic model with an active suspension system in the presence of uncertainties and actuator faults. The proposed control scheme uses a sliding-mode controller to generate the tracking signal to the valve for each of the four wheel subsystems for mitigating three degrees of freedom (3-DOF) heave-roll-pitch motion arising from road undulations. For each of the electrohydraulic valve-cylinder pair in each subsystem, an adaptive proportional-integralderivative (PID) controller is proposed. Designing an adaptation scheme for the PID gains to accommodate actuator faults is among the main contributions of this work. The focus on actuator faults is motivated by the fact that loss of actuator effectiveness is a critical fault scenario in vehicle suspension systems and that the probability of occurrence of faults in actuators is higher and more severe when compared with other components. To analyze the performance of the proposed approach, computer simulations are carried out to illustrate control performance, robustness, and fault tolerance. The performance of our approach is then compared with that of the sliding-mode control (SMC) approach presented by Chamseddine and Noura. Results clearly indicate the strength of the adaptation scheme and its ability to mitigate fault effects in a short time. Simplicity of the overall scheme and the stabilization of the system under both faulty and fault-free conditions are the main positive features of the proposed approach.