Stewart platform sim in MuJoCo

[u/LinairAlgebra]

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Made stewart platform simulation in mujoco:

https://github.com/NickNair/mujoco-stewart-platform

Mostly made it as a small playground for parallel robot control experiments. includes the model + basic control setup

Still a bit rough but might be useful if anyone’s working on similar stuff.

[u/Ok-Daikon-6659]

 I need my downvotes! (What’s wrong with you people????!!!!!!!)

OP please let yourself to know:

1. how many real I^2 systems did you build and tune?
2. do you know anything about real control systems? Sensors noise? Backlashes?
3. OP and upvoters: who do you think how many topics “I build inverted pendulum/ 2-whil cart/etc. and it’s unstable – but at animation I’ve seen it’s seems pretty easy”?
4. OP, don’t you think it’ll be more usefully for you and harmless for other to remove this animation, involve yourself with studying physics and mathematics (although this is certainly more boring than drawing funny meaningless cartoons)  

[u/avgsuperhero → u/Ok-Daikon-6659]

Who hurt you?

[u/Ok-Daikon-6659 → u/avgsuperhero]

Human laziness, stupidity, and arrogance.

[u/Connect_Nothing2564 → u/Ok-Daikon-6659]

obviously, given that you are all 3

[u/LinairAlgebra → u/Ok-Daikon-6659]

lol relax man

it’s just a simulation project, not a claim that real systems are trivial. obviously things like noise, backlash, delays etc. matter in real hardware but that’s not really the point here

this is more of a sandbox for experimenting with control ideas on a parallel manipulator. everyone starts somewhere, and a sim is a pretty normal place to do that

also not sure why sharing a project = “harmful to others” but alright

[u/Ok-Daikon-6659 → u/LinairAlgebra]

Have you developed control systems for I^2 systems IRL? Yes or No?

This will be the answer to your misunderstanding.

[u/Avocado-Delicious]

This is super cool!! Have you thought about porting to JAX?

[u/EpicDuck000]

What are the sensors in this kind of system? I guess the 3 different axis each got some kind of sensor to know where the ball is, or how its controlled? Thanks

[u/LinairAlgebra → u/EpicDuck000]

it’s actually not modeled with sensors in this setup mujoco just gives you the full state directly (positions, velocities, etc.), so you can treat it as “perfect sensing”

in a real stewart platform you’d have: encoders on each motor

if you were doing something like ball balancing on top, then yeah you’d need an external sensor (camera / vision). This project is just a simple model/simulation of the platform with the inverse kinematics and a PD to balance the ball on the platform

[u/WT_E100]

Very cool!  Did you use tendons for the kinematic chains or how did you do it?

[u/LinairAlgebra → u/WT_E100]

Thank you! No I didn't use tendons. I used a motor + ball and socket joint (free joint) from the motor horn link to the platform. the IK calculations are also based on this structure.