Abstract: Traditional four-wheel independent steering(4 WIS) control strategies often fail to maintain kinematic constraints under wheel disturbances, compromising vehicle motion coordination. To address this, a cooperative control strategy based on the instantaneous center of rotation(ICR) is proposed. First, vehicle dynamics, steering mechanism, and overall energy consumption models are established. The Fermat point is introduced as the ICR when wheel axes do not intersect, and a virtual linkage mechanism is designed to correlate wheel steering angles under uncertainty, ensuring real-time kinematic constraints. A compound control strategy is developed, where a target control loop drives the wheel angles to converge to the desired values, and an instantaneous control loop ensures tracking of the ICR to maintain kinematic coordination. These loops work collaboratively to improve vehicle motion coordination and control robustness. Finally, using steering angles, tire sideslip angles, vehicle kinetic energy, total steering energy consumption, and tire slip loss as evaluation metrics, the proposed strategy is validated through Matlab/Simulink simulations and experiments on a self-developed 4 WIS electric forklift under different disturbance conditions. Results show that under single-wheel disturbances, compared to position control, the proposed strategy reduces the average maximum tire sideslip angle by 68.38% and slip loss by 22.26%, effectively enhancing vehicle motion coordination under uncertainty.

Key words: four-wheel independent steering vehicle, fermat point, instantaneous center of rotation, kinematic constraints, cooperative control