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Robot falling apart on unsmooth terrain

asked 2015-01-05 09:20:08 -0500

peci1 gravatar image

I have a multi-link robot SDF in Gazebo 2.1. It is a simple "static" model with just inertia and collision elements defined, no transmission elements or motors specified.

When I let the robot fall down on a plane, everything is ok.

However, I need to use a terrain model obtained from point cloud triangulation. Such terrain contains lots of small triangles with varying normals and errors (because of precision of the measurements and triangulation). When I let the robot fall on this terrain, it instantly begins to fall apart (even if the terrain is quite planar/the normals do not differ much).

My workaround so far is to preprocess the SDF to remove all joints (in different words - the links remain, just the joints are static), so that for every joint config I have a different SDF model. Highly ineffective, I know. Luckily, by this modification, the model stops falling apart and behaves in an expected way.

Do you have an idea on how to have a model with non-static joints that doesn't fall apart?

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How are you defining the model to be static? A model that has been defined as static will not fall. Could you post your model's SDF file?

nkoenig gravatar imagenkoenig ( 2015-01-07 10:24:03 -0500 )edit

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answered 2023-05-20 05:28:42 -0500

peci1 gravatar image

Usually, this happens if the Gazebo model has fixed joints and there are some parts with highly different inertia scales (or even just shapes, e.g. the inertia is very "thin" in one dimension). In such cases, it is better to either edit the inertia of all robot parts to be more of a similar scale, or the lump the fixed joints so that they are no longer joints (basically the approach described in the question).

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Asked: 2015-01-05 09:20:08 -0500

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Last updated: May 20