Date of this Version
Interaction between robot and environment is an extremely important aspect of robotic research. Compliance helps reduce the impact effects of robot/environment interaction. Hybrid position/force control is important in most robotic tasks; accurate position control is needed in unconstrained directions, and accurate force control is needed in constrained directions. Force control can be more responsive with a compliant force/torque sensor, but positional accuracy is reduced with compliance. An instrumented compliant wrist device can be used to achieve both responsive force control and accurate position control.
The wrist is connect in series between the end of the robot and the tool, and is designed to partially surround the tool, thus reducing the distance between the end of the robot and the end of the tool. The wrist device uses rubber elements for compliance and damping, and a serial linkage, with potentiometers at each joint, is used for sensing the deflections produced in the wrist.
This document describes the newest version of the instrumented compliant wrist, including modifications and improvements to the wrist described in "Design of a Tool Surrounding compliant Instrumented Wrist", available as tech report MS-CIS-91-30, GRASP LAB 258 from the University of Pennsylvania. Changes include a more protective sensing linkage structure and improved electronics. The compliance, kinematics, and accuracy of the wrist are presented. Also, software for determining the wrist transform, and plans for the wrist are given.
Thomas Lindsay and Richard P. Paul, "Improved Instrumented Compliant Wrist Design", . October 1992.
Date Posted: 25 July 2007