constraint Jacobian mis-allocation

[nisal-perera]

Intro

Hi!

I am a PhD student using Mujoco to simulate a bipedal robot with closed chain mechanism.

My setup

I am using Mujoco 3.2.4 on ubuntu 20.04 with C++.

My question

I made a mujoco model for my biped robot and created the closed-chain mechanism using equality () constraint. I made sure to use the bare minimum number of equality constraints to defined my model. When i fix the robot w.r.t. the world (i.e. remove the ) i can simulate the robot with the linkages. However, when i add the to make the robot a floating base, I get cannot simulate the model. I get the following error "Error:engine error: mj_makeConstraint: constraint Jacobian mis-allocation:found nnzJ=642 but allocated 594".

I tried increasing the njmax and nconmax and other size values but it did not seem to help fixing this issue. Any help to get around this issue is appreciated.

Confirmations

• I searched the latest documentation thoroughly before posting.
• I searched previous Issues and Discussions, I am certain this has not been raised before.

[yuvaltassa]

This is a serious bug! That error message should never happen.

Please submit a proper bug report with a minimal reproducible example and we will look into it ASAP.

Please take care to make your MRE

1. Minimal: try to reduce the model as much as possible while still maintaining the error. Specifically if you could make a model that does not require binary assets (meshes/textures), that would be highly appreciated.
2. Reproducible: Make sure we have everything we need to reproduce the error.

[aryakeyvan-star]

I am getting the same error message. Are there any work arounds to get around this issue?

[yuvaltassa]

This is fixed since 3.2.5

[Wan020607]

Will the above problem happen in issac sim if I want to use mjcf