Precision robotic manipulator

Industrial Robot

ISSN: 0143-991x

Article publication date: 1 August 2000



Hollingum, J. (2000), "Precision robotic manipulator", Industrial Robot, Vol. 27 No. 4.



Emerald Group Publishing Limited

Copyright © 2000, MCB UP Limited

Precision robotic manipulator

Precision robotic manipulator

Keywords: Robots, Manipulators

Applicant: Univ. California (US)Patent number: US5811951Publication date: 22 September 1998Title: High precision redundant robotic manipulator

A high precision redundant robotic manipulator is intended for overcoming obstacles or a highly congested work space. One embodiment of the manipulator has four degrees of freedom and another embodiment has seven degrees of freedom. Each of the embodiments uses a first selective compliant assembly robot arm (SCARA) configuration to provide high stiffness in the vertical plane, a second SCARA configuration to provide high stiffness in the horizontal plane. The seven degree of freedom embodiment also utilizes kinematic redundancy to provide the capability of avoiding obstacles that lie between the base of the manipulator and the end effector or link of the manipulator. These additional three degrees of freedom are added at the wrist link of the manipulator to provide pitch, yaw and roll. The seven degrees of freedom embodiment uses one revolute point per degree of freedom. For each of the revolute joints, a harmonic gear coupled to an electric motor is introduced, and together with properly designed based servo controllers provides an end point repeatability of less than 10 microns. Kinematic redundancy is used in robotic manipulators to overcome constraints imposed by obstacles or by limited or congested work space. Also, a selective compliant assembly robot arm (SCARA) has been utilized to provide high stiffness in the horizontal plane of the robot's work space. For a compact manufacturing automation station with a substantial number of pieces of process equipment densely packed within the operational volume, robotic manipulators which provide both kinematic redundancy and selective compliance are critically needed. For example, for optoelectronics (OE) manufacturing automation, the requirements call for the handling of optical fibres, and its precise placement to within 10 microns. This high degree of repeatability, coupled with the kinematic redundancy requirement has been accomplished by the present invention in a typical automation platform constrained to an approximate footprint of under 0.5 square metres.

Jack Hollingum