Sliding mode control for an obstacle avoidance strategy based on an harmonic potential field

This paper introduces a new integrated path control strategy (combined path planning and motion control) for autonomous systems of arbitrary dimension. A harmonic artificial potential field is used to specify admissible trajectories leading around obstacles. Using a sliding mode controller, motion is generated along the gradient lines of the potential field, avoiding collisions with the obstacles. The extremely low computational complexity of the proposed method makes it very suitable for online applications. The strategy is applied to mobile robots moving amidst known obstacles. Only the obstacle closest to the robot is considered at each time instance. The switching of the two respective gradient fields along the equi-distance line between two obstacles leads to the interesting phenomenon of an additional “spatial” sliding surface, which is examined in detail. The algorithm guarantees approaching the goal point continuously, following a reasonably short path. Numerical examples are presented to demonstrate the utility of this new strategy