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Make a kinematic only model [closed]

asked 2016-06-17 10:40:41 -0500

Brosseau.F gravatar image

Hello everybody,

I have a robot model written in urdf and I want to make it move with a linear/angular speed command. So I have modified the planar_move plugin. I also had to make some links (not close to the ground) kinematic to avoid bad orientation in turn. But I still have a small bias in the trajectory following (which works fine with the diff_drive plugin).

I tried to disable gravity, set constraint solver iterations to 0, set all the links to kinematic. But when the robot receives an angular speed (take a turn), all the links falls apart.

Some possibilities :

  • Maybe the little bias can be corrected with follower's parameters (but I don't want to change them to test that specific version)

  • I am probably making some mistakes in using kinematic. I saw some posts about it but no answer. What is the steps to follow in order to use a kinematic only simulation ?

Thanks in advance.

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Closed for the following reason the question is answered, right answer was accepted by Brosseau.F
close date 2017-12-05 04:05:26.399051

1 Answer

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answered 2016-10-21 01:42:27 -0500

Brosseau.F gravatar image

updated 2017-12-05 04:04:39 -0500

Workaround: I made a plugin to apply speed to the base link of my robot.

This plugin will also set links (which are not parents on a joint) with no friction.

And it's working pretty nice.

Update :

This plugin was working with a model with unrealistic inertial matrix. When I tried it on a more realistic model a bias between the wanted angular speed and the actual one appeared.

As I said here (, the solution is to switch the root link of the model to be kinematic (SetKinematic method). And then you can apply the wanted speed with SetLinearVel and SetAngularVel.

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Asked: 2016-06-17 10:40:41 -0500

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Last updated: Dec 05 '17