Elbow does not bend compared to ground truth

[fbrand-new]

Hi,

First of all thanks for your great work!

I noticed the following behavior when rendering different joint positions with dr robot with respect to the ground truth robot pose provided by mujoco as can be seen in the following videos:

elbow1.mp4

Dr robot output is on the left, mujoco output is on the right. All the videos are produced with the provided ur5 pretrained model. The start and end joint configuration for each video are randomly generated and the trajectory is done by interpolating the configurations.

elbow2.mp4

elbow_wrist3.mp4

In all three of these videos, it seems to me that dr robot struggles to "bend the elbow" of the robot compared to the ground truth given by mujoco.

I am aware that the data generation process discards - or at least tries to discard - configurations that result in a collision, so I am aware that some configuration might be impossible to obtain (like the one in the first video). Nonetheless this should not be a sufficient explanation to why this pattern occurs also with configurations that are relatively distant from collisions.

Do you have a hint on what may be the issue here?

I can share the code used to generate this if it can be helpful

Thanks