Technical Reports (CIS)

Document Type

Technical Report

Date of this Version

April 1991


University of Pennsylvania Department of Computer and Information Science Technical Report No. MS-CIS-91-30.


Interaction between robot and environment is an extremely important aspect of robotic research. Compliance helps reduce the effects of impact when there is robot/environment interaction. To accomplish useful tasks, it is important to implement hybrid control; accurate position control is needed in unconstrained directions and accurate force control is needed in constrained direction. Force control can be more responsive with a compliant force/torque sensor [3], 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 connected in series between the end of the robot and 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 defections produced in the wrist. Several major improvements are proposed for the Xu wrist. The wrist can be designed to surround the tool, thus reducing the distance between the end of the robot and the end of the tool, thus reducing the distance between the end of the robot and the end of the tool. The compliant structure is redesigned for more even compliance, and the sensing structure kinematics are simplified. In this over, the compliance, kinematics, and accuracy of the wrist will be presented. Also, software for finding the wrist transform, and plans for the wrist are given.



Date Posted: 08 August 2007