IJCAS

This study presents a velocity and yaw rate control algorithm for a wheeled mobile robot (WMR) equipped with active four-wheel steering (A4WS) and four-wheel independent drive (4WID) systems, designed to enhance cornering performance during negative-phase maneuvering. To achieve zero-sideslip cornering (ZSC) and maintain the desired turning radius, the algorithm adjusts additional front and rear steering angles while independently driving all four wheels. The proposed control algorithm consists of two components: lateral and longitudinal controllers. The lateral controller determines the additional front and rear steering angles based on a kinematic commanded steering angle, and the longitudinal controller calculates the torque for each wheel using the kinematic relations of the steered wheels, considering tire sideslip effects. The design also considers unmeasurable tire drag forces and the mutual interactions between the two controllers. Numerical simulations validate the advantages of the proposed algorithm over traditional controllers.

Keywords: Active steering system, four independent-wheel drive, four-wheel steering, torque allocation, wheeled mobile robot, zero-sideslip-cornering.