Extensible cable in MuJoCo

[Bruurman]

Hi all,

I'm a graduate student at TU/e simulating a tethered two-robot system in MuJoCo.

MuJoCo: 3.7.0
Python: 3.12.3
Ubuntu: 24.04

Currently tried with the mujoco.elasticity.cable plugin - I've also experimented with flexcomp, both currently have a fixed length. Question:

• The real cable is spooled on a winch, so its free length changes at runtime. The approaches I can think of are: (a) dynamically adding/removing composite segments each step -- though I'm not sure how computationally tractable this is, (b) fixing the segment count and running separate simulations for different cable lengths under a prescribed motion, or (c) some tendon-based approach. The winch tries to keep the cable taut with a certain tension, and I'd like to study how sag and oscillation evolve during prescribed motions of both robots, ultimately for collision avoidance. Is there a recommended pattern for any of this?

Any pointers or existing examples (which I missed) would be very much appreciated. Thanks!
tether.xml

[codymarquardt]

Also interested in something very similar, would appreciate guidance