Mechatronic model based overshoot prediction and reduction in servodrives with compliant load

A common problem in motion control is the onset of vibrations due to the inertial forces when a compliant load is being displaced. It is the case of the vibration of large machine tools, but also the vibration of slender loads in pick&place. The main goal of the present work is to predict and minimise the overshoot that a compliant load moved by a servodrive suffers when it reaches the final position. Instead of modifying the control algorithm or adding dampers, the authors propose an optimal path planning based on the selection of a square sine velocity profile, a standard in machine tools NCs. Thus, a 3 degrees of freedom mechatronic model that integrates the dynamics of the drive-transmission-compliant load system and the control has been developed to predict the overshoot. Analysing the velocity profile, it has been possible to determine several values of the commanded jerk that minimize the overshoot and are related to the natural frequency of the compliant load. The prediction of the overshoot magnitude as well as the optimal jerk values have been experimentally validated in a workbench with a single axis with a ball screw transmission and a compliant load where a laser interferometer has been used to measure the overshoot. (c) 2019 Elsevier Ltd. All rights reserved.