Accessing and modifying cable parameters via MjModel or MjData from python

[shamilmamedov]

Hi,

I am a PhD student working on modeling and manipulation of linear deformable objects (e.g., cables, ropes) using MuJoCo.

Although I am aware that guidelines and routines for System Identification (SysId) are not yet available, I want to perform parameter estimation for a cable model using zeroth-order, gradient-free optimization techniques. Specifically, I am interested in estimating the twist, bend, and density parameters of a cable. For this purpose, the ability to modify these parameters directly in the model would be extremely beneficial. I have managed to access the masses and inertia of the capsules via model.body_mass and model.body_inertia. However, I have not found a way to access the twist and bend parameters. Could you advise if it's possible to access these cable twist and bend parameters (cable stiffness) through the Python interface?

Thank you in advance for your assistance.