Home | Tutorials | Wiki | Issues
Ask Your Question
0

ODE Joint, Static friction

asked 2012-11-09 09:34:22 -0600

this post is marked as community wiki

This post is a wiki. Anyone with karma >75 is welcome to improve it.

Dear All,

In my model I have a horizontally placed slider joint, this gradually moves because apperently numerical error cause it to not be exactly horizontal (angular noise with a magnitude of ~ |1e-4|). Because there is no friction, it drifts towards it's limit. (The bounce at the limit is somewhat unrealistic too, but im not interested in that atm (it adds energy, despite the settings)).

Not an issue since the real robot will also be imperfect. However static friction in the slider joint should stop it from moving, however this settings seems to have no effect! I've noticed in ODE documentation that regular joints (and Gazebo api), that regular joints don't have such atributes (static friction), only the contact joint has this. I'd be great if static friction would work, any way this is possible. Here is the joint code:

<joint name="joint_2" type="prismatic">
    <parent>link_1r</parent>
    <child>puppet</child>
    <pose>0.0000 0.0000 0.00000 0.0000 0.0000 0.0000 </pose>
    <axis>
        <xyz>0 1 0</xyz>
        <limit>
            <lower>-0.1</lower>
            <upper>0.1</upper>
        </limit>
        <dynamics>
            <damping>0.01</damping>
            <friction>0.1</friction>
        </dynamics>
    </axis>
</joint>

I can create some actual contact friction, by recreating bearings and such, but that seems overly complication and prone to error.

Thanks

edit retag flag offensive close merge delete

1 Answer

Sort by ยป oldest newest most voted
0

answered 2013-01-11 19:15:34 -0600

this post is marked as community wiki

This post is a wiki. Anyone with karma >75 is welcome to improve it.

You are correct that we do not currently support joint friction with ODE. I've added this to the gazebo issue tracker as issue #381.

edit flag offensive delete link more
Login/Signup to Answer

Question Tools

1 follower

Stats

Asked: 2012-11-09 09:34:22 -0600

Seen: 1,794 times

Last updated: Jan 11 '13