The calibration of machine tools or industrial robots needs high precision 3-dimensional coordinate measurements. Common available systems still have the need of ambitious and time extensive processes to fulfill the requested requirements. Therefore there is a strong request for fully automated systems that allow an autonomous and easy to handle procedure for 3D volumetric deviation measurements. This exactly is the intension of the here presented 3D Coordinate Measurement System. The so called µ-GPS System is based on reliable white light interferometer and robust technology. The 3D coordinates are determined via trilateration from three measured distances like it is known from the global GPS. Mainly two parts, the sensor unit (transceiver unit) including the emitter and the reference base (three cat’s-eyes) which includes the three reflectors are mounted in the workspace of the machine. A model to evaluate the signals was developed which allows in combination with a 3-dimensional failure correction a 3D accuracy of more than 5 microns. This application will be the base for an exemplary and fully automated calibration process of Swiss-type turning machines. As these machines are used in high volume manufacturing for precision parts, they need to be assembled and calibrated very accurately. For the long term stability the µ-GPS System can be easily assembled in the Swiss-type turning machine so that thermal deviations and abrasion can be measured and compensated in the control. The robust and easy handling of the µ-GPS System later allows an expansion of the showcase to robots and other machine tools.
Science Journal 