dartsim: Support joint dynamics parameters on Ball joints

[azeey]

Desired behavior

Support for parameters such as damping on ball joints.

Alternatives considered

none

Implementation suggestion

Currently, none of the dynamics parameters are supported. The comment on

gz-physics/dartsim/src/SDFFeatures.cc

Line 1120 in 62ee52c

// SDF does not support any of the properties for ball joint, besides the

indicates that this is because SDFormat doesn't support it and the following issues confirm that:

gazebosim/sdformat#331
gazebosim/sdformat#1250
gazebosim/sdformat#860

However, maybe we can add an implementation where the parameters from the first <axis> are used for all the DOFs.

Additional context

none

[vbalaji21]

Can you please let me know when will this feature be implemented ? Because I am looking for a 3 DOF rotational joint with damping. I am not able to have any work around for this problem as I am unable to have 3 rotational joints on the same spot.

[azeey]

I've added the help wanted label. We are currently not planning to work on this in the near term, but would accept pull requests.