I have always utilized position loop to control servos in Rockwell motion. I recently encountered an issue where a process would push against a servo-controlled motor, causing a torque spike and potential servo fault due to position error tolerance being exceeded. To address this, I temporarily implemented a solution by sending an MSF to the servo to allow it to be pushed, and then issuing an MSO once the pushing had ceased. While this workaround is effective, I am concerned about the strain it may put on the servo drive if it is turned off and on every minute. I came across a Rockwell document detailing how to control torque, which could potentially be beneficial for my application. However, I am curious if there is a more efficient way to allow the servo to be pushed slightly without needing to constantly power cycle it.
Increase the position error limit in the axis properties to effectively monitor and manage position errors. Regularly check the torque and make adjustments as needed. While the Rockwell AOI tool may have some limitations, it can still provide valuable insights into your system. Utilize SSVs to fine-tune position and velocity errors, set torque limits, and keep a close eye on position errors. If errors surpass a certain threshold, consider homing the axis and resetting the errors. To prevent position errors after a push, use redefine position to realign the axis. Additionally, lower the torque limit on the pushed axis to prevent excessive strain. This comprehensive approach will help optimize system performance.
Robertmee suggested adjusting the position error limit in the axis properties and closely monitoring the position error to take appropriate actions. He emphasized the importance of using torque to home frequently. While the Rockwell AOI may have limitations, it serves as a helpful starting point for gaining insights. By utilizing SSVs to expand position and velocity error, limiting torque, and monitoring position error, the system can be maintained within operational limits. In case of a push, it is advisable to redefine the position to prevent unnecessary position error reduction. Reducing the torque limit on the pushed axis can prevent excessive strain. Consider implementing torque to home before handling packages to minimize package misshaping. By adjusting torque limits and monitoring position errors, the servo can operate more smoothly without reaching error limits.
Hugheydarryl expressed gratitude for the response and is contemplating utilizing a torque system every time a package is picked up and transported, where the next step involves the object pushing against the servo holding it. The position error limits are set high enough to prevent the servo from faulting when pushed, but the torque will increase significantly in an effort to maintain position, potentially causing slight deformities to the package. It is suggested to adjust the torque limit to allow the servo to relax more easily without reaching the position error limit. This can be achieved by setting the torque limit when pushing against it and then restoring it once the task is complete.
You're on the right track with thinking of transitioning to torque control for your application. It provides you with precise control, not only of position, but also of how much force the servos are exerting. Consequently, it sounds like your application could benefit from shifting to a torque control loop. This way, you can dynamically alter the amount of resistance offered by your servos, effectively "cushioning" the push from the process, without necessitating to power cycle the servo constantly. Do give the Rockwell document a thorough read to better grasp the concept. However, remember that tuning and stabilization might be a bit challenging in the beginning, but once you cross that hurdle, I believe your issue could be resolved more efficiently.
✅ Work Order Management
✅ Asset Tracking
✅ Preventive Maintenance
✅ Inspection Report
We have received your information. We will share Schedule Demo details on your Mail Id.
Answer: Answer: The common approach is to utilize a position loop to control servos.
Answer: Answer: One temporary solution is to send an MSF to the servo to allow it to be pushed, and then issue an MSO once the pushing has ceased. However, this workaround may result in strain on the servo drive if power cycled frequently.
Answer: Answer: A potential solution could involve utilizing Rockwell's torque control techniques, as detailed in a relevant document, to manage torque more effectively and potentially address the issue without frequent power cycling.
Join hundreds of satisfied customers who have transformed their maintenance processes.
Sign up today and start optimizing your workflow.