A practical approach to compensate for geometric errors in measuring arms: application to a six-degree-of-freedom kinematic structure

This paper presents a practical approach to the compensation of geometric errors in measuring arms. The intent of this work is to give a set of useful and ready-to-use indications and computational suggestions to those who are concerned with improving the accuracy of such a system by means of off-line kinematic calibration. The reader is introduced to the main concepts related to the kinematic performances of a measuring arm and guided through the main steps involved in the error compensation process. A basic mathematical formulation is adopted and an iterative linearization of equations, based on a least-squares algorithm, is used for kinematic parameter estimation. The well-known simplicity of the approach and its effectiveness is demonstrated experimentally on a real six-degree-of-freedom measuring arm.