Have no idea how to make a link rotate around its parent joint

[zhuoqun-chen]

Dear developers,

I use phobos to load a quadrupedal robot urdf into my scene and I want to use python to set the joint angles for each frame to rotate links. But It seems that I can only directly set rotation XYZ Euler to the armature, but the animation seems to be incorrect:

You can see in this picture that the calf link rotates exceeding the maximum limitation around the joint (bone) during the animation, however, the value used is within the safe range. This may imply, I guess, that only rotate the armature is somehow incorrect.

So I want to rotate bones in edit mode or pose mode to see if rotating joints (bones) will be correct. But I can't even rotate bones directly in blender's GUI.

Could you give me some help or advice? Thank you very much!

[hwiedPro]

Hi @zhuoqun-chen,
can you provide some information on how you defined the joint? Did you do it manually, loaded it from URDF etc...?

[zhuoqun-chen]

Hi hwiedPro,

Thank you for the quick reply! And I solved the problem already.

I found that I have to use bpy to control the pose bone Euler Angle directly instead of the armature Euler Angle. This may be because pose bone corresponds to actual joint so it respect the maximum and minimum limitations (armature doesn't).

[hwiedPro]

I'm happy that you found a way and thanks for sharing your solution!