Active fault tolerant control of electric power steering system with sensor fault

Considering the assist characteristics failure of electric power steering (EPS) system caused by the sensor fault, this paper presents a fault tolerant control strategy based on fault estimation and reconstruction. The EPS model with torque sensor and the motor current sensor fault is established. By the observer technology and the linear matrix inequality, robust sensor fault estimation with H_∞ performance index is achieved; the sensor reconstruction is derived from the fault estimation and sensor fault output, the reconstruction value is then used as the input of the EPS system controller to realize fault tolerant control. The simulation result in Matlab/Simulink environment shows that: when the common fault of the torque sensor and the current senor occurs, the designed estimation algorithm could estimate sensor faults accurately; While the fault tolerant control can provide approximately equivalent assist performance of fault EPS to the normal one, which promotes the stability and security of EPS to a large extant.