UR10e Robot Drift Compensation for Precision Measurement Applications

This paper deals with the possibility of low-cost on-line compensation for thermally induced error. The aim is to compensate the drift of the UR10e collaborative robot to the extent that the robot operates with the repeatability guaranteed by the manufacturer for the thermal steady state. Thus, the authors have developed a compensation system that predicts drift and, by applying it in the robot control, can reduce the difference in positioning between the cold and warm robot. A measurement nest equipped with confocal sensor and a pair of laser profilers was used to measure repeatability. The robot was also equipped with sensors for temperature detection. The tests were carried out under different conditions and ISO 9283:1998 standard was also considered. By applying the proposed methodology, drift can be compensated with a high degree of efficiency. In some measurements the drift was compensated completely, usually the compensation efficiency was around 90%. Thanks to the compensation system, it is not necessary to pre-warm the robot and, above all, it is possible to guarantee a predetermined level of repeatability regardless of the actual robot or ambient temperature.