System Design , Modelling , and Control of a Four-Wheel-Steering Mobile Robot

This paper describes a dynamic model and crosscoupling control of a mobile robot with four independently steered and driven wheels. The dynamic model incorporates the components of the wheel mechanisms, backlash effects of the wheel actuators and nonlinear forces produced by the tire-ground interaction. The problem of computationally efficient control of the vehicle is solved using a low-level control loop that cross-couples steering and driving motors and is utilized in conjunction with a kinematics-based trajectorytracking controller. The results of simulation show significant reduction of the vehicle slip with moderate trajectory-tracking errors.