How do I set the initial shape of flexcomp? #2151

walt666 · 2024-10-18T00:27:24Z

walt666
Oct 18, 2024

Intro

Hi!

I am a graduate student , I use MuJoCo for my research on soft robot.

My setup

MuJoCo 3.2.3

My question

I want to use the membrane in flexcomp to simulate the elastic rope, the membrane is connected to the box at both ends, and there is a large box between them. The box in the middle is not connected to the membrane, the membrane is just pressed on the box. The connection scheme is shown in Figure 2. I tried to use equality to connect, but the initial state of flexcomp was straight and could not be bent, so I failed. I was wondering what I could do to make that happen, thank you in advance.

Minimal model and/or code that explain my question

If you encountered the issue in a complex model, please simplify it as much as possible (while still reproducing the issue).

Model:

minimal XML

<mujoco>
  <include file="scene.xml"/>
  <extension>
    <plugin plugin="mujoco.elasticity.shell"/>
    <plugin plugin="mujoco.elasticity.membrane"/>
  </extension>

  <option timestep="0.001" solver="CG" tolerance="1e-6" integrator="implicitfast"/>

  <size memory="10M"/>

  <visual>
    <map stiffness="100"/>
  </visual>

  <default>
    <default class="wall">
      <geom type="plane" size=".5 .5 .05"/>
    </default>
  </default>

  <worldbody>
    <light diffuse=".5 .5 .5" pos="0 0 3" dir="0 0 -1"/>
    <body name="box1" pos="1 0 .3">
      <freejoint />
      <geom name="box11" type="box" size=".3 .3 .3" rgba="0 .9 0 1"  />
      <site name="end1" pos="-.3 .0175 -.3" size="0.005"/>
    </body>

    <body name="box2" pos="-1 0 .3">
      <freejoint />
      <geom name="box22" type="box" size=".3 .3 .3" rgba="0 1 0 1"  />
    </body>

    <body name="box3" pos="0 0 .5">
      <freejoint />
      <geom name="box33" type="box" size=".2 .2 .5" rgba="1 .9 0 1"  />
    </body>

    <body name="CB" pos="0 0 1.3">
      <flexcomp type="grid" count="42 2 1" spacing="0.035 0.035 0.035"  
              radius=".001" mass="10" name="plate" dim="2" rgba=".8 .2 .1 1" >
          
        <contact condim="3" solref="0.01 1" solimp=".95 .99 .0001"/>
        <edge equality="false" damping="10"/>
        
        <plugin plugin="mujoco.elasticity.membrane">
          <config key="poisson" value="0.1"/>
          <config key="thickness" value="0.01"/>
    
          <config key="young" value="3e6"/>
            
        </plugin>
      </flexcomp>
    </body>
    
  </worldbody>

</mujoco>

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How do I set the initial shape of flexcomp? #2151

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How do I set the initial shape of flexcomp? #2151

walt666 Oct 18, 2024

Intro

My setup

My question

Minimal model and/or code that explain my question

Confirmations

Replies: 0 comments

walt666
Oct 18, 2024