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 unknown environment. In this study the cause of the limit cycle is analysed intuitively and then proved mathematically, leading to a necessary condition for identifying the critical points from which the robot likely starts a limit cycle path. By taking into account the abrupt change of the target orientation at the critical points, a virtual target strategy is proposed for resolving the limit cycle problem, in which the real target is switched to a virtual location following the critical point 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 condition for switching back to the real target is established using a specific change in the obstacle information sensed. Main features of the proposed strategy are highlighted by comparing with other approaches for handling the local trapping problems. Efficiency and effectiveness of the proposed approach are verified through simulation and experiments.
virtual target mobile robot limit cycle reactive navigation fuzzy logic