EXPERIMENTAL INNOVATION TO COMPENSATE POSITIONING INACCURACIES OF INDUSTRIAL ROBOTS WITH HIGH PAYLOAD CAPACITY

The issue of the absolute accuracy of large and very large industrial robots when handle heavyweights is still a challenge in the world of robotic engineers due to a complex of structural deformations in the robot joints and control modelling. It is almost impossible to master the reactions of these robots in complex industrial applications, where introducing small variations such as variable weights, variable gauges, and variable part models, positioning accuracy is strongly affected at high working speeds. In this paper, a methodology for measuring, predicting, and compensating end-effector’s positioning errors is presented. Measurements are done with metrologically certified instruments, like spacing measuring instruments, and comparator watches. An error prediction model is constructed to find out the positioning error at the tool center point (TCP) of the robot, for different payloads and different distances of the TCP relative to the robot base system. Tests indicates very good results for payloads above 550 kg, TCP speeds of 1000 mm/s and target points at over 3500 mm from the robot base.