Design of Observer-Based Adaptive Fuzzy Fault-Tolerant Control for Pneumatic Active Suspension with Displacement Constraint

This study deals with the fault tolerance problem of an active air suspension system considering parametric uncertainties and sprung mass displacement in the event of sensor fault and unmeasured signals. A pneumatic spring is used to set up a quarter of the car model to investigate the flexible stiffness and provide an active force that can suppress chassis vibrations. To approximate unknown nonlinear parameters of air spring actuator dynamics, fuzzy logic systems (FLSs) are used as function approximators. Sensor failure is considered while all system states are assumed to be unmeasured variables. A fuzzy state observer is then designed to approximate the unknown system states and overcome the effective loss of sensor fault. Adaptive fault-tolerant control based on command filter backstepping technique to solve the problem of exploding complexity. To enhance tracking accuracy, this study involves a prescribed performance technique such that the sprung mass displacement is guaranteed between the predefined boundaries. Finally, the effectiveness of the proposed control is verified by comparative simulation examples under the presence of sensor fault and unknown system states.