Compared to their repeatability, the accuracy of industrial manipulators is disappointingly poor. To permit off-line programming of manipulators and interaction with their local sui rounds a high positional accuracy is required; this is particularly true for operation under supervisory control. The accuracy of a manipulator can be improved by calibration of its link lengths and joint angle measurements.This paper presents the results of the calibration of a PUMA 560 industrial manipulator and discusses simplifications to the procedure and theory which improve the practicality of the method without seriously compromising the results. Circle point analysis is used with data points being recorded by a pair of theodolites; the relevant theory is presented in the Appendix. A joint error correction function is produced for each joint. A fourfold improvement in accuracy is demonstrated without unduly increasing the complexity of the kinematics or requiring a sophisticated end effector.

A R Greig

Papers

Improvement of the Accuracy of a PUMA 560 Industrial Manipulator by Calibration