Robot Manipulator Based on a Wire-driven Variable Link Mechanism to Control Workspace

Robot manipulators have recently been introduced in various industrial automation processes. The payload and workspace of manipulator are determined according to the process to be performed. Most commercially available robot manipulators are designed with links whose lengths are fixed, based on which their workspaces are fixed. When the payload or workspace increases due to changes in the process, a manipulator with different specifications is required. As the length of the links increases to accommodate a larger workspace, the size of the robot increases, requiring a larger collision-free region. In this paper, we propose a robot manipulator that can control its workspace by using the wire-driven variable link mechanism. The proposed mechanism resulted in a 119.71% increase in the workspace of the robot manipulator, while simultaneously reducing the weight and inertia of the robot manipulator’s links by approximately 15.79% and 16.865%, respectively. Furthermore, without additional wire tension maintenance device design, we proposed an effective method for maintaining wire tension through the position and current control of the joint actuators. Through object grasping experiments, the proposed manipulator showed more effective manipulation than the fixed link manipulator.