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Catherine_Bernier
Posts: 144 Handy
How to avoid the robot to stop when an impact occurs? |
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/ Most recent by matthewd92
in Robot Safety
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in Robot Safety
I just got a question from a customer.
In the process, the robot can't really stop if an impact occurs because it then needs someone to reset and restart it. Hence, the robot safety basics cause the robot to stop on an impact.
Is it possible to simply make the robot compliant upon impact? Meaning that if an impact occurs, the robot will compensate but never stop running?
Can the robot be reactivated without a specific human intervention?
The goal is to stay safe of course.
In the process, the robot can't really stop if an impact occurs because it then needs someone to reset and restart it. Hence, the robot safety basics cause the robot to stop on an impact.
Is it possible to simply make the robot compliant upon impact? Meaning that if an impact occurs, the robot will compensate but never stop running?
Can the robot be reactivated without a specific human intervention?
The goal is to stay safe of course.
Catherine Bernier, Jr. Eng.
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Etienne_Samson Beta Tester Beetle, Wrist Camera URCap 1.3.0, Vacuum Beta tester Posts: 419 Handy
@Catherine_Bernier the FT Sensor can indeed be used to improve the collision detection provided with the UR.
A few things to remember:- The sensor is not safety rated
- Whatever program you build around the sensor signal, it will never overcome the UR safety settings.
- Sensor recommended threshold is 5N in X and Y et 2N in Z
- Build a thread where you continuously look over the force signals in Fx, Fy, Fz
- Have a collision force threshold
- Build an "if" loop where you would stop, slow down or change direction if you detect a force higher then your threshold.
- To have a good accuracy on the force, you need to slow down, if you move at full speed your prorgram will not have time to react on the force reading and you will probably end-up
Etienne SamsonTechnical Support Director+1 418-380-2788 ext. 207
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https://www.linkedin.com/in/catherinebernier
Is it possible for you to share how do you setup that behavior a bit more technically?
What force mode type do you use (Simple, Frame, Point, Motion)?
What kind of features you define to achieve the desired motion if any, or if you use Tool or Base as features?
I guess for your usecase, you add a MoveL (as opposite to MoveP or MoveJ) within the Force Mode command, is that right?
Again, thanks in advance.
The secret that I found to using the force mode effectively is to limit the speed in which the axis is able to move in compliance. If you don't do this the robot tends to "flop" over on itself. This was the Aha moment for me in using the force wizard.
Just to be sure, in the description, you said you are sliding in X, so you don't want to tic the compliant along X as shown in the screenshot, is that right? I guess you meant to tic Y, otherwise the robot won't follow the X-component of the waypoint if I understand well the tic/not-tic behaviors in the compliant field, plus you would want to set a force threshold higher than zero along the sliding direction as well, right?... This different behavior obtained by ticking or not that field is what I find a bit misleading in the user manual.
Thanks!
Would this be accepted according to safety regulations? In my head, upon collision with an operator, you need to stop the robot to avoid further damage to the operator. The stop signal in the UR caused by a peak in force is probably dual channel safety and hence Safe to use to detect collision. However, is the force data that we can use in force mode a dual channel signal as well that we can use?