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Why collision is not working for UR5

asked 2022-05-19 23:38:21 -0500

CroCo gravatar image

updated 2022-05-19 23:39:05 -0500

I'm using UR5 robot in Gazebo but I've noticed when there is no controller, the collision detection is not working in Gazebo 9. I'm wondering what is the problem. As you can see in the below picture, some parts penetrate others. I'm using the files in universal robot. I see the collision models are provided in urdf file. I'm using melodic in Ubuntu 18.04.

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answered 2022-05-20 02:58:42 -0500

Joe28965 gravatar image

It's probably because self_collide is off by default for links. As the description reads, it will not collide with links of the same model.

This can be very desirable if you have (for instance) a car, where you have set the chassis as a simple square representation. That would mean half of the wheels technically collide with the chassis. Since a square would be used to simplify computations (by a significant amount) it's desirable to use.

In your case, I can imagine you want to have self_collide turned on. However, it's also good to check how the collisions look and if they don't have a little overlap by default.

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how to turn it on?

CroCo gravatar image CroCo  ( 2022-05-20 14:23:00 -0500 )edit

By adding the tag

<gazebo reference="**link_name**">
     <self_collide>true</self_collide>
</gazebo>

Note that links that share a joint will never collide with one another. So parents will never collide with children or the other way around.

Joe28965 gravatar image Joe28965  ( 2022-05-20 14:28:12 -0500 )edit

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Asked: 2022-05-19 23:38:21 -0500

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Last updated: May 20 '22