A virtual target approach for resolving the limit cycle problem in navigation of a fuzzy behaviour-based mobile robot

A virtual target approach is proposed for resolving the limit cycle problem in navigation of a behaviour-based mobile robot. Starting from the onset point of a possible limit cycle path, the real target is switched to a virtual location and the robot is navigated according to the virtual target set up temporarily and the real environment information sensed, until a switching-back condition is reached. The cause of the limit cycle is analysed and the abrupt change in target orientations at two consecutive reaction instants is then identified to be the condition for shifting the target from the real location to the virtual one. The condition for switching back to the real target is established using a specific change in the obstacle information sensed. The algorithm is described together with some particular considerations in implementation. Efficiency and effectiveness of the proposed approach are verified through simulation and experiments conducted with a Nomad 200 robot incorporating a fuzzy behaviour-based controller.