Dynamic joints for simulating modular robots

Discussion in 'Modeling' started by Shanmukh Alle, Jun 22, 2018.

  1. I am new to mujoco.
    I have a modular robot with screw joints that I want to simulate, I would like to simplify the screw joint with a dynamic contact joint that can be enabled/disabled programmatically during simulation.
    Is there a way to do that?
    The video of coupling of the robot can be found here -> https://goo.gl/1KC75J
  2. Emo Todorov

    Emo Todorov Administrator Staff Member

    Nice robots! The best way to simulate this in MuJoCo is to use equality constraints (connect or weld in this case -- note that the weld constraint will be improved in the 1.60 release in a couple of weeks). Equality constraints have enable flags that can be changed at runtime. So when you want the modules to stick together, just set that flag to 1. If the modules are not close, the constraint will pull them together. You can use the corresponding solref/solimp parameters to adjust the softness of the constraint.
  3. Thanks!

    I've tried using the connect constraint but I am unable to get it to work.
    I built a sample with 2 blocks with a connect constraint between them.
    The two blocks didn't come together when the connect constraint is enabled but when I moved one block the other moved.
    I am unable to understand how to use the connect constraint.
    Please help!

    The video of the simulation can be found here -> https://goo.gl/vboj1r

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