Issue #494 resolved

Make joint axis reference frame relative to child

Steven Peters
created an issue

In the sdf documentation, the <joint><axis> element is listed as using the joint frame, when in practice it uses the model frame (see Joint.cc:175-191).

I recommend fixing the code to match what the documentation currently says, rather than just changing the documentation, since it will simplify model creation to fix this.

We should test the PR2, Atlas, Polaris, and other models to ensure that fixing this bug does not break things.

Comments (12)

  1. felix-kolbe

    Confirming, voting for code fix.

    We're just trying to describe our robot with SDF 1.3 and found that awkward behavior. E.g. we want to revolve around the z axis of a link frame we tilted but have to define the corresponding model axis (y in this case) as the joint axis. That way it works but is confusing nonsense.

  2. John Hsu

    upgrading this to critical, as the current interpretation is non-ideal. Exactly how to make the change and changing code without breaking existing user code might take some time to tic-toc.

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