Yaw moment control through adaptive four-wheel independent steering (4WIS): methodology and simulation

This work presents the design and simulation of a control system for a vehicle equipped with Four-Wheel Independent Steering (4WIS). This technology enables individual control of the steering angle at each wheel, allowing real-time corrective actions based on estimated vehicle state variables. The proposed control architecture includes a dual-objective feedback controller that simultaneously regulates yaw rate and sideslip angle through weighted correction when deviations from reference values are detected. To overcome the limitations of standard non-adaptive allocation methods, a Weighted Pseudo-Inverse Control Allocation (WPCA) strategy is implemented to distribute the required yaw moment among the four wheels utilising time-varying weighting matrices updated online in accordance with vehicle dynamics and tire limitations. Sideslip angle is estimated online using a mathematical model based on vehicle state variables, while tire cornering stiffnesses are also estimated in real time. These estimates are directly embedded into the WPCA allocation layer to improve accuracy, particularly under low-friction conditions. The complete control framework has been developed in MATLAB/Simulink and integrated with a high-fidelity 14-degree-of-freedom vehicle model. The system has been tested across different driving scenarios and friction conditions to comprehensively evaluate its stability, responsiveness, and robustness, demonstrating clear technical advantages over conventional 4WIS fixed-parameter control allocation architectures.