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Why are contacts so unstable?

I use this gz topic to get contact data /gazebo/default/physics/contacts and I'm try to get a center of pressure, but it turns out like something in this pic sss.jpg

I also uploaded a vid for showing how contacts are shaky. https://drive.google.com/file/d/0B4bNDF3keBFieUVSd2hjS0Ztb1k/view?usp=sharing

Asked by soshiant1992 on 2015-11-21 02:02:38 UTC

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Thats how contacts look for me as well under ODE. I think with bullet I used to get stable contacts, however other issues appeared, maybe it works for you.

Asked by AndreiHaidu on 2015-11-25 09:43:41 UTC

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There are a few parameters you can use to stabilize contacts. There are many factors that affect contact stability, some come from your robot controller and some from the physics engines.

See for example this world: https://bitbucket.org/osrf/gazebo/src/c2bc0849e68ba3b2f30ffae4249f41c086324f17/test/worlds/contact_stability.world?at=default&fileviewer=file-view-default

Or the drcsim example.

We can take this offline (by creating an issue). Best case scenario is that your model or some subset of your model that demonstrates the unstable-ness is added to our integration test suite as an example of how to create stable contacts for future simulation modelers to follow.

John

Asked by hsu on 2015-11-25 12:57:22 UTC

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