Steering Instantaneous Center Synchronization Tracking Control Strategy Considering Multiple Time Delays

The four-wheel independent steering system (4WIS) has four steering angle modules, which independently control the steering angle of the modules to make vehicle trajectory tracking more accurate. However, the tracking performance of a single steering angle module is degraded due to input and state time delays, while the communication time delay among the four steering angle modules causes the steering instantaneous center synchronization performance to be degraded and unfocused at the same point, resulting in a decrease in the accuracy of vehicle trajectory tracking. To address the above problems, an instantaneous center synchronization tracking control strategy considering multiple time delays for 4WIS is proposed, which includes two parts: inner angle tracking control and outer instantaneous center synchronization control. The inner layer is a sliding mode model predictive controller (SMMPC), which predicts the system state under the influence of input and state time delays and introduces a sliding mode surface to improve the error shrinkage rate, ensuring the tracking accuracy of a single steering angle module under the influence of time delay. The outer layer is an instantaneous center synchronization controller considering communication time delay, which solves the communication time delay effect between steering angle modules by introducing predictive states in the inner layer. Combined with average deviation coupling synchronization control, it compensates for the synchronization error of the steering angle module and ensures the instantaneous center synchronization accuracy under the influence of communication time delay. The simulation and experimental results show that the strategy proposed in this article can effectively improve the instantaneous center synchronization accuracy of 4WIS and thus ensure trajectory tracking accuracy.