Virtual target strategy in fuzzy navigation of reactive mobile robots

Reactive mobile robot often suffers from a so-called limit cycle problem - the robot wanders indefinitely in a loop in the course of navigation in unk nown environment. In this study the cause of the limit cycle is analysed in tuitively and then proved mathematically, leading to a necessary condition for identifying the critical points from which the robot likely starts a li mit cycle path. By taking into account the abrupt change of the target orie ntation at the critical points, a virtual target strategy is proposed for r esolving the limit cycle problem, in which the real target is switched to a virtual location following the critical point and the robot is navigated a ccording to the virtual target set up temporarily and the real environment information sensed, until a switching-back condition is reached. The condit ion for switching back to the real target is established using a specific c hange in the obstacle information sensed. Main features of the proposed str ategy are highlighted by comparing with other approaches for handling the l ocal trapping problems. Efficiency and effectiveness of the proposed approa ch are verified through simulation and experiments.