Fault-tolerant control approach based on constraint control allocation for 4WIS/4WID vehicles

The four-wheel independently driven and steered electric vehicle is a promising vehicle model having a strong potential for handling stability, flexibility, and consumption reduction. However, failure of the actuators of 4WIS/4WID vehicles could lead to performance reduction and dangerous accidents owing to their complex system. A fault-tolerant control approach is adopted in the integrated chassis controller such that the autonomously driven vehicle maintains its safety and stability while actuator failures occur. A linear quadratic regulator is utilized to track the reference path by adjusting the total forces and moment. To resolve any actuator failures, a control allocation method based on the pseudo-inverse matrix is introduced for decoupling the forces and moment based on the current state of the tires with cycle and correction. In the actuator control layer, the desired forces of the tires are achieved by regulating the steering angles and driving torques based on the inverse tire models of normal and flat tires. Three sets of experiments are used to test the efficiency of the proposed method when applied to a 4WIS/4WID vehicle. The results demonstrate that the proposed fault-tolerant control method can greatly improve the tracking performance and stability of 4WIS/4WID vehicles under conditions of actuator failures.