Spawn URDF Joint Stiffness

asked 2012-02-09 08:38:30 -0600

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I am trying to spawn a URDF model in Gazebo without loading a controller for the robot. I have found that the joints are very 'floppy' when no controller is loaded. Is there a command in the launch file or urdf which will increase the joint stiffness if no controller is running?

-Kyle

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answered 2012-02-10 00:58:19 -0600

DimitriProsser

11163 ●79 ●116 ●169

You could try setting the joint friction and/or damping to a very high value.

<joint name="joint_name" type="continuous">
    ...
    <joint_properties damping="1000.0" friction="1000.0"/>
</joint>

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I did have this previously with damping at 100 and friction at 1000, and after playing with the values from 0 up to 10^5 it still seems that there was no difference. These properties seem to come into play with the transmission and controllers running. Hmmm..

kmaroney ( 2012-02-10 01:32:01 -0600 )edit

If no controllers are running, why can't the joints just be fixed?

DimitriProsser ( 2012-02-10 02:13:32 -0600 )edit

Yep, not a bad idea for a completely static robot model. However I do plan on writing controllers and using the robot in sim. Just wanted to see if there was a quick fix, much like launching joints at explicit angles with -J joint_name 0.4 etc.

kmaroney ( 2012-02-10 05:13:52 -0600 )edit

1

This post is quite old, but if possible plz reply. What if I have objects like cupboard and there doors are opening and closing w/o any apparent reason. I want ROBOT to close and open them. in that case I guess I'll not write a controller for cupboard. How to make the doors remain in one position?

aknirala ( 2012-09-08 10:31:44 -0600 )edit

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answered 2019-08-14 05:16:20 -0600

Thibault_Rouillard
26 ●3 ●4 ●7

If you want the joints to remain static you can also set turnGravityOff to true for each link

<link name="my_link"/>
...
<gazebo reference="my_link">
<material>Gazebo/Blue</material>
<turnGravityOff>true</turnGravityOff>  
</gazebo>

Hope that helps

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