Cylindrical Manipulator Path Planning Among Static Obstacles Using Artificial Potential Fields

Abstract

In this paper, path planning for cylindrical manipulator of 4-DOF is studied. Another view point is presented for using so called 'artificial potential fields' which is used as the base of searching for new and safe points in the manipulator's workspace among static obstacles. Three vectors are used for safe manipulator navigation. The first vector is determined between the end-effector and the goal points and it is used to attract the end-effector to the goal point. While the second and third vectors are computed from points defined on the obstacle and the end-effector. These two vectors are used to repel the end-effector and the arm from the boundaries of the obstacles. In this work, the obstacles are suggested to have a cylindrical shape with different sizes. Displacement detections between the manipulator (its end-effector and arm) and the obstacles are used as sensors for collisions impending. A random movement is suggested for joint two to avoid contacting between the arm and obstacles. At the off-line path mode, all path points are determined by the presented method and some of them are updated, if an arm collision is detected, then joint variables are calculated at each point. In real mode, these joint variables are fed to a simple real control system to make the manipulator tracks the found path. The method gives a safe path for undertaken manipulator. An experimental work is also presented.