Motion Control Resources
B&R Servo Drives Detect and Correct Following Error Automatically
B&R Industrial Automation Posted 05/15/2014
Compensating for errors in advance
B&R servo drives detect and correct following error automatically
B&R continues to expand the functionality of its ACOPOS line of servo drives. Repetitive control – B&R's latest advancement – considerably improves the accuracy of production processes with stationary disturbances by using predictive following error compensation. The performance of the machine or system is considerably increased without a great deal of additional effort. Repetitive control is available for all ACOPOS models simply by installing a firmware update.
When using position-controlled drives with constant speed, mechanical conditions can cause stationary disturbing torque fluctuations, which often results in following error localized to a certain area. Optimizing the drive controller configuration can minimize these lag errors but will not be able to completely prevent the disturbance.
Embedded in the standard speed control loop for the ACOPOS drive family, repetitive control adjusts the torque setpoint of the drive in a way that drastically reduces the periodic portions in the speed or following error. The algorithm undergoes a constant learning process so that changes to the load profile – caused by wear, for example – have no effect whatsoever on the drive due to predictive compensation for disturbances.
Available as an add-on to the standard control procedure, active disturbance suppression is easy and intuitive to configure, not even requiring a mathematical model thanks to the extremely adaptive nature of the algorithm.