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Tim_SmithTim_Smith Posts: 38 Apprentice
in Robot Safety
Hi guys,

I tried integrating a SICK safety scanner with a UR5 robot last week. My goal was to have the go into Reduced Mode settings as soon as the robot moved across a certain line. I had no problem setting up the safety area and editing the safety settings for the Reduced Mode. However, the robot's transition into the reduced mode is very sudden and creates a jerking motion when crossing the line. The only way I managed to reduce the jerking motion was to reduce the speed and acceleration differences in the settings.

Is there a way to create a smooth transition between the normal working settings and the reduced mode settings with Universal Robots?
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  • abeachy_HG24abeachy_HG24 Posts: 79 Handy
    @tim_smith I have found that the best way to do these transitions is to have a waypoint right before where the robot would be entering reduce mode and slow down the acceleration. I normally do not change the speed much when doing this, I just focus on the acceleration. Just play around with it until it is a fairly smooth transition.

    Another thing that can make a big difference is using a blend radius on that waypoint to smooth it out a little more.
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  • abeachy_HG24abeachy_HG24 Posts: 79 Handy
    @tim_smith Out of curiosity, is there a reason behind using the safety scanner to put the robot into reduced mode? You could do the same thing with the built in safety planes of the UR.  
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  • Tim_SmithTim_Smith Posts: 38 Apprentice
    @abeachy_HG24 Thanks for your input! I agree with your solution for most situations. However, if someone approaches the robot, you cannot predict where the robot will be in the program, so having a waypoint right before the robot enters reduce mode will not help in this situation. 

    My goal here is to change the robot's speed when someone approaches the robot. For example:
    • 3m = 100% speed
    • 2m = 50% speed
    • 1m = 0% speed
    Having a safety scanner will give an input to the robot when a person crosses a certain plane, whereas the UR's safety planes will not be triggered when  a person gets too close to the robot.



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  • abeachy_HG24abeachy_HG24 Posts: 79 Handy
    @tim_smith Ah okay, I understood it that it was just if the robot enters that area. But yeah, whenever a person enters that space could be very unpredictable and cause those sudden jerky movements. I think the best thing would be to change the difference between the normal and reduced mode settings.
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  • Tim_SmithTim_Smith Posts: 38 Apprentice
    @abeachy_HG24 Thanks for the input. The differences between the normal mode and the reduced mode even triggered an emergency stop when the safety scanner was triggered. I did change the reduced mode settings, and this helped a lot, but to have a smooth transition I had to have almost the same settings between these two modes. This defeats the purpose of having a safety scanner.

    @Stefan_Stubgaard
    Do you know if there is a way to smoothly transition from normal mode to reduced mode when using a safety scanner?
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  • Stefan_StubgaardStefan_Stubgaard Posts: 43 Handy

    @Tim_Smith @abeachy_HG24There is no way to smoothen the transition when transitioning between Normal and Reduced mode and vice versa.

    During certification of the Safety system, it was a demand from the notified certification body, that the transition must be completed within a given timeframe in order to conform with the safety standards.

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  • Tim_SmithTim_Smith Posts: 38 Apprentice
    edited December 2016
    @Stefan_Stubgaard Thank you for the explanation. So it would be best to use a safety scanner to momentarily stop the robot? I saw a video where a Kuka iiwa would change its speed when a person would approach the robot. I believe they were using a safety mat to tell the robot how close the person was from the robot :
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  • Stefan_StubgaardStefan_Stubgaard Posts: 43 Handy

    @Tim_Smith If you want to dynamically change speed of robot depending on distance between robot and operator, yes then a safety scanner or safety mat can be used.If you just want to pause the robot when an operator is approaching, a light barrier can be used to trigger safeguard. This is often the more affordable option.
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