Integrated Fault Estimation and Fault-Tolerant Control for Drive-by-Wire Steering Systems in Four-Wheel Independent Drive Vehicles

This study proposes an integrated fault estimation and fault-tolerant control strategy for actuators of four-wheel independently driven vehicles. Firstly, a modeling approach is developed by combining the vehicle dynamics model with the steering actuator model to establish a system model in the presence of actuator faults. Subsequently, to simultaneously estimate the system states and actuator faults, an unknown input observer (UIO) is designed, treating actuator faults as unknown state variables and augmenting the system state variables to achieve simultaneous estimation of states and faults, providing a foundation for subsequent fault-tolerant control research. The gain matrices of the fault observer and the fault-tolerant controller are both obtained through single-step linear matrix inequality (LMI) computations, realizing the design of an integrated fault-tolerant control system. Finally, the effectiveness and superiority of the proposed method are verified through hardware-in-the-loop experimental tests.