mujoco: Implement AttachFixedJointFeature and DetachJointFeature#1001
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- Implemented `AttachFixedJoint` using MuJoCo equality weld constraints. - Optimized `AttachFixedJoint` and `DetachJoint` to reuse and toggle constraints (`active = 0/1`) to avoid expensive `mjModel` recompilations. - Implemented `CastToFixedJoint` to identify fixed joints. - Added comprehensive unit tests in `detachable_joint.cc`. Generated-by: Gemini 3.1 Pro Signed-off-by: Addisu Z. Taddese <addisuzt@intrinsic.ai>
iche033
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Jun 9, 2026
| const char *n1 = mjs_getString(eqSpec->name1); | ||
| const char *n2 = mjs_getString(eqSpec->name2); | ||
| if (!n1 || !n2 || std::string_view(childBodyName) != n1 || | ||
| std::string_view(parentBodyName) != n2) |
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do you need to check if childBodyName / parentBodyName are null?
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I don't think it's possible to have a body without a name. It's assigned immediately after creation:
Do you think we should still add the extra check?
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Mainly because I saw the use of std::string_view which does not work well with nullptr. Yeah if mjs_getString(mjs_getName(childLinkInfo->body->element)) never returns null then I think it should be fine.
Signed-off-by: Addisu Z. Taddese <addisuzt@intrinsic.ai>
iche033
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Jun 10, 2026
shameekganguly
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Jun 26, 2026
* mujoco: Implement AttachFixedJointFeature and DetachJointFeature - Implemented `AttachFixedJoint` using MuJoCo equality weld constraints. - Optimized `AttachFixedJoint` and `DetachJoint` to reuse and toggle constraints (`active = 0/1`) to avoid expensive `mjModel` recompilations. - Implemented `CastToFixedJoint` to identify fixed joints. - Added comprehensive unit tests in `detachable_joint.cc`. Generated-by: Gemini 3.1 Pro --------- Signed-off-by: Addisu Z. Taddese <addisuzt@intrinsic.ai>
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🎉 New feature
Part of #299
Summary
AttachFixedJointusing MuJoCo equality weld constraints.AttachFixedJointandDetachJointto reuse and toggle constraints (active = 0/1) to avoid expensivemjModelrecompilations.CastToFixedJointto identify fixed joints.detachable_joint.cc.Test it
Screenshot
Orbital Centrifuge Target Game (gist
detachable_joint_space.sdf)A physics-based timing game in Gazebo Sim using the MuJoCo plugin. Players must trigger the detach command at the perfect millisecond to launch the rotating payloads through the target gate.
Note: Developing this demo exposed a reset bug where dynamic weld constraints failed to update their relative offsets after a simulation reset. The recording demonstrates that this is now resolved and working properly.
Checklist
codecheckpassed (See contributing)Generated-by: Gemini 3.1 Pro
Note to maintainers: Remember to use Squash-Merge and edit the commit message to match the pull request summary while retaining
Signed-off-byandGenerated-bymessages.Backports: If this is a backport, please use Rebase and Merge instead.