Window-shaped obstacle avoidance for a redundant manipulator

The window-shaped obstacle avoidance problem is studied in this paper. Several research papers regarding obstacle avoidance including the method proposed by Zghal et al. (1992), which we believe is the most suitable for 3D window-shaped obstacle avoidance were studied. Consequently, several short-comings of the Zghal´s method were discovered. The Zghal´s method will produce a chattering problem due to its deficiency in determining the shortest distance between the manipulator links and the window edges. This paper proposes a new scheme to determine the shortest distance. This new scheme will remedy the chattering problem. Moreover, the most dangerous link (MDL) method is developed to further improve the effectiveness and efficiency. Because the MDL method only considers the most dangerous link in the performance criterion, the online weighting assignment problem of the Zghal´s method is removed, also, less redundancy is required to accomplish the goal for obstacle avoidance. Therefore, the MDL method will allow more redundancy to be useful for the other goals under multiple-goal application environments