An Approach of Collision Detection and Link Identification for Two-Link Flexible Manipulators Using Nonlinear State Estimator

Abstract

In use of a multi-link flexible manipulator in general environments such as homes and offices, collisions between the flexible manipulator and various obstacles and/or working humans is unpredictable and brings serious damage to the manipulator and humans or obstacles. For example, when the flexible manipulator is used for assistant of the meal, humans or obstacles can be moving in the work space of the flexible manipulator. It causes the collision between the flexible manipulator and the unknown obstacles and there are the cases which cannot be avoided the collision. In order to reduce the damage of the manipulator and the humans and then to re-plan the path plan to the desired position, the unexpected contacts or collisions should quickly be detected and the collided link should be identified for reacting to suspend the motion of the manipulator and for planning new path. This paper presents a method of collision detection for each link of a two-link flexible manipulator by introducing respective collision detection function based on residual processes generated by the innovation process of a nonlinear state estimator. Furthermore, the mathematical structure of collision detection for each link is investigated.