An Event-Triggered Steering Angle Collaborative Control Strategy for the Four-Wheel Independent Steering System

The four-wheel independent steering(4WIS) system has the characteristic of wholly independent and controllable four-wheel steering angles. It can achieve new modes such as wedge driving (with the same four-wheel steering angle) or even lateral driving (with all four-wheel steering angles of 90 degrees) through four-wheel steering angle coordination, making its stability judgment and control method completely different from traditional four-wheel steering systems. This poses challenges to the design of the steering angle coordination controller. To solve the above problems, the control requirements under different steering modes, such as 4WIS conventional/unconventional, are discussed, and a control objective design method is established considering the asymptotic evolution characteristics of the 4WIS critical stability boundary. Considering that the dynamic acquisition and control of 4WIS control objectives need online optimization, which will consume many computing resources, an event-triggered stability control method is proposed based on the dynamic redistribution of lateral force. The results show that the method proposed in this paper can make the 4WIS system self-adaptive and fast and smooth switching mode. The stability can be ensured by redistributing the lateral force so that the system can meet both the manoeuvrability and stability requirements.