Avoiding steering actuator saturation in off-road mobile robot path tracking via predictive velocity control

In mobile robot path tracking applications, an autonomous vehicle is steered to stay as close as possible to a desired path. If lateral wheel slip is an important variable, as it is the case at high speed and due to low tire-ground friction in off-road applications, limits of the steering actuators, the major input constraints of the system, have a major influence on the tracking control performance. This paper presents an algorithm to control the longitudinal velocity, a secondary control variable, of a mobile robot in order to respect the boundedness of the steering angle, and thus to improve the vehicle safety. The applicability of the algorithm has been verified through experiments with an off-road mobile robot.