Suggestion on Diffik_nullspace

Hey,

Amazing work!

I am trying to integrate the same with Xarm in my environment. I am facing an issue with the mj_integratePose line in the "diffik_nullspcae.py". My data.nv is of size 20 and data.nq is 19, out of which I just need only the first 7 joints. I am able to calculate the jacobian but while running the integratepose function, there is a size mismatch(as the arguments takes "model", q,qdot,dt).
Can you please suggest what can be done to avoid this?

Thanks!

Start by reading diffik_nullspcae.py and locating the mj_integratePose call. Check how model, q, qdot, data.nv, and data.nq are shaped, and reproduce the mismatch with the reported 20-velocity, 19-position model. Done means establishing a supported way to integrate the first seven joints or documenting why the requested setup cannot be used.

Written by the indexing model from the issue text.