An Obstacle Avoidance Algorithm for Hyper-Redundant Manipulators

Many tasks which manipulators must perform occur in the presence of obstacles. While a variety of algorithms for nonredundant and mildly redundant manipulators exist, little analysis has been performed for a class of robots with the most to offer in the area of obstacle avoidance: hyper-redundant manipulators. The term "hyper-redundant" refers to redundant manipulators with a very large, possibly infinite, number of degrees of freedom. These manipulators are analogous in morphology and operation to "snakes," "elephant trunks," and "tentacles." This paper presents novel kinematic algorithms for implementing planar hyper-redundant manipulator obstacle avoidance. Unlike artificial potential field methods, the method outlined in this paper is strictly geometric. 'Tunnels' are defined in a workspace in which obstacles are present. Methods of differential geometry are then used to formulate equations which guarantee that sections of the manipulator are confined to the tunnels, and therefore avoid the obstacles. A general formulation is given with examples to illustrate this approach.