mujoco

<mujoco>

  <default>
    <joint damping=".01" frictionloss=".1"/>
  </default>

  <worldbody>
    <light pos="0 0 1"/>
    <geom type="plane" size="1 1 .01" pos="0 0 -1"/>
    <body pos="0.15 0 0">
      <joint name="hinge" axis="0 1 0"/>
      <geom type="capsule" size="0.02" fromto="0 0 0 .1 0 0"/>
      <body pos="0.1 0 0">
        <joint type="slide" axis="1 0 0" stiffness="200"/>
        <geom type="capsule" size="0.015" fromto="-.1 0 0 .1 0 0"/>
        <body pos=".1 0 0">
          <joint type="ball"/>
          <geom type="box" size=".02" fromto="0 0 0 0 .1 0"/>
          <body pos="0 .1 0">
            <joint axis="1 0 0"/>
            <geom type="capsule" size="0.02" fromto="0 0 0 0 0 .1"/>
          </body>
        </body>
      </body>
    </body>
  </worldbody>

  <actuator>
    <motor joint="hinge"/>
  </actuator>
</mujoco>