Kinematic Path Control of a Redundant Robot Arm in Sliding Mode

Abstract

Robot arms with redundant degrees of freedom are well known to match the flexibility of motion inherent to the human hand. This is typically useful for most industrial robots where one of the design requirements is to execute work operations with more natural kinds of movements. Such work tasks are performed subject to different constraints, while the end- effector tracks a given path in task space. In the general case task constraints can be mapped into admissible ranges of variation of the joint variables. This paper elaborates a method for kinematic path control in sliding mode employing vector space methods. The sliding mode control makes use of the redundant degrees of freedom of a robot arm to satisfy the constraints of the joint variables during the motion of the end- effector along a prescribed path in task space. In fact the proposed method allows the robot arm to reconfigure similarly to a human hand movement, while retaining the assigned end- effector movement. The method is computationally efficient and it is suitable for kinematic control when the number of the degrees of freedom of the robot arm is greater than the dimension of the task space.