Obstacle avoidance for kinematically redundant robots using distance algorithm

The redundancy of robot manipulators plays an important role in increasing their flexibility and versatility, especially in an environment with obstacles. In this paper, the redundancy is utilized for enabling collision-free motion for a given trajectory of a manipulator end-effector. Manipulator links and obstacles are approximated by polytopes that are described by their vertices. The distance algorithm, which allows computation of the distance information between polytopes in R^m, is used to obtain distance information between robot and obstacles. Three kinds of method based on the distance information-gradient projection method, obstacle avoidance force method, obstacle avoidance velocity method-are proposed to calculate the joint trajectory that enable a manipulator to perform a desired end-effector motion and avoid obstacles. A simple numerical example involving a two-dimensional five degree-of-freedom manipulator working among obstacles is described