Characterisation Of 3-d Cartesian Co-ordinateLaser Interferometer Tracking System

Calibration is an important process to assess and maintain the accuracy of machine tools. Most acceptance tests are based on static measurement cycles which are time consuming and laborious. With the development of laser tracking systems (LTS) it is possible to calibrate a machine tool both statically and dynamically. This paper presents a simple approach to construct a 3-D laser tracking system based on Cartesian co-ordinates. This system employs a laser interferometer for displacement measurement as well as a reference datum to perform the automatic tracking of a moving object, a Co-ordinate Measuring Machine (CMM) as the tracking mechanism and an analogue PID controller to control the tracking system. The prototype system has been constructed, assembled and tested. Results presented here are on the characterisation of the whole system, including the static and dynamic tests of the tracking mechanism, the CMM. System models have been obtained by using identification technique and the simulated results are verified by the experiments.