Delta Operator-Based Model Predictive Control with Fault Compensation for Steer-by-Wire Systems

In a Steer-by-Wire (SbW) system, the mechanical linkages which connect the steering wheel to front wheels are replaced by a digitally controlled steering system. In spite of improved vehicle safety due to better steering capability, the SbW system actuator failure may lead to unwanted steering performance or even instability. A fault tolerant model predictive control (MPC) with fault compensation for SbW systems based on delta operator for actuator faults is proposed. It deploys an observer to estimate both the fault information and the faulty SbW system states. At each sampling time, the MPC immediately compensates for the fault. The gains of the observer and the fault tolerant MPC controller are obtained by solving a linear matrix inequality derived from the Lyapunov theory. The simulation results illustrate that the proposed fault tolerant control strategy can counter the various types of actuator faults and maintain superior steering performance to shift operator-based MPC controller.