Map joint name to generalized coordinate index #2525
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IntroHi, I'm a student working on robot simulations. My setupMuJoCo 3.2.5 Python My questionHow does one find the index or indices in mujoco's generalized coordinate system that correspond to a given joint name?
corresponding to a given joint name. Is there a method that gives the index-range of a subtree? For instance, when having multiple robots within a scene, it would be nice to get the individual robots' mass matrices and jacobians. Thanks for your help Minimal model and/or code that explain my questionConfirmations
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Replies: 1 comment 8 replies
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def dof_width(joint_type: mujoco.mjtJoint) -> int:
"""Get the dimensionality of the joint in qvel."""
return {0: 6, 1: 3, 2: 1, 3: 1}[joint_type]
def qpos_width(joint_type: mujoco.mjtJoint) -> int:
"""Get the dimensionality of the joint in qpos."""
return {0: 7, 1: 4, 2: 1, 3: 1}[joint_type]
qvel_ids = []
qpos_ids = []
for joint_name in joint_names:
jnt_id = model.joint(joint_name).id
jnt_type = model.jnt_type[jnt_id]
vadr = model.jnt_dofadr[jnt_id]
qadr = model.jnt_qposadr[jnt_id]
vdim = dof_width(jnt_type)
qdim = qpos_width(jnt_type)
qvel_ids.extend(range(vadr, vadr + vdim))
qpos_ids.extend(range(qadr, qadr + qdim))
qvel_ids = np.array(qvel_ids)
qpos_ids = np.array(qpos_ids) |
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Ah that's strange, we'll fix. |
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My bad. You want The error message needs to be updated. |
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I did try this also but in the above code yields the same error message. I'm fairly certain it's not available, at least not in the 3.2.5 Python version I'm using: |
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mmmm, I fixed the error message and added a test in 305b68e ? |
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Oh I haven't pulled the latest yet, will try, I'm sure it works now. Thank you very much @yuvaltassa @kevinzakka for being so responsive, it's very helpful |
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mmmm, I fixed the error message and added a test in 305b68e ?