What happens on collision?

xArm/850 Troubleshooting
1

Hi xArm community.
I’m considering xArm for one of my projects, however that shall work with human (not alone in the cage!).
Hence have questions about collisions:

  1. What happens if arm collides itself?
  2. What happens if it touches the solid surface and can’t move it?
  3. What happens if it touches a human? What’s the max impulse of such hit?
  4. Does arm raise an error/exception in API or just stops?

I assume 5 6 7 models behave alike, do they?

2

What happens if arm collides itself?
It will report collision error, you need set the collision sensitivity at least to level 1, level 0 is turn off, level 5 is most sensitive.
What happens if it touches the solid surface and can’t move it?
The joint will move back 3° automatically from the colision surface, it’s a function named collision rebound in the xArm Studio which you can turn it off.
What happens if it touches a human? What’s the max impulse of such hit?
Just like the first question, it will report collision error if you turn on the collision detection.
The max impulse depends on the speed and the payload whie the collison happens.

Does arm raise an error/exception in API or just stops?
It will raise error/exception while there is collision or the other errors.

3

Thanks a lot for fast and detailed response!

What is the sensitivity of levels? In kg, Newton or whatever you measure it. Couldn’t find it anywhere…

Real world example: what if a kid puts a hand on a table where arm is about to put Lego brick?

4

It’s measure in Newton, since the collision detection is measured by current, it’s hardly provide a specific force, but we can try to provide a force range for each sensitivity level and update to the user manual.
What if a kid puts a hand on a table where arm is about to put Lego brick?
Actually we do not recommend to set up the robot to a place where a kid can access, it’s too dengerous. If it really hit a person and you did set the collision sensitivity level to 5, it will do significant less harm to person compare with turn off the collision detection.

Thanks for your feedback.