Mud plugin with non static models

asked 2016-06-20 21:38:23 -0600

lonewolf gravatar image

updated 2016-06-21 14:49:12 -0600

With regards to this question where I am tying to pick a soft ball, I tried to use the mud plugin for the entire ball. But mud plugin seems to work only for static objects. If static is false, then the object just falls through the ground plane, is there way of making the plugin work with non static models?

ball.sdf

<model>
  <link>
    .....
    <geometry>
      <sphere>
        <radius>0.13</radius>
      </sphere>
    </geometry>
    <collision name='collision'>
      <geometry>
        <sphere>
          <radius>0.13</radius>
        </sphere>
      </geometry>
      <surface>
        <contact>
          <collide_without_contact>true</collide_without_contact>
          <!-- <collide_without_contact_bitmask>3</collide_without_contact_bitmask> -->
        </contact>
      </surface>
    </collision>
    <sensor name="mud_contact" type="contact">
      <always_on>true</always_on>
      <update_rate>1000</update_rate>
      <contact>
        <collision>collision</collision>
      </contact>
    </sensor>
  </link>
  <plugin name="gazebo_mud" filename="libMudPlugin.so">
    <contact_sensor_name>ball/mud_contact</contact_sensor_name>
    <!-- <contact_surface_bitmask>3</contact_surface_bitmask> -->
    <stiffness>0.8</stiffness>
    <damping>100000.0</damping>
    <link_name>finger::finger_link</link_name>
  </plugin>
</model>
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Comments

Can you describe what you're expecting to achieve? As I understand it, the mud plugin makes a model penetrable, but with resistance.

chapulina gravatar imagechapulina ( 2016-06-21 10:41:30 -0600 )edit

@chapulina I am trying to throw a ball using two arms, but I don't read too much into to the size of the ball as such. Therefore during the process the ball is squeezed a lot (this is how it happens in the real world), I wanted to do the same in gazebo. So just modelling the ball using a sphere doesn't work as it jumps around, so I thought that using the mud plugin would help achieve the process.

lonewolf gravatar imagelonewolf ( 2016-06-21 14:44:58 -0600 )edit
1

have you tried to model soft contact using params first? I am sure we can get stable soft contact by just setting up the model right. You'll get a much more predictable simulation this way. Using mud plugin is not designed to do what you are suggesting here.

hsu gravatar imagehsu ( 2016-06-22 13:06:28 -0600 )edit

@hsu Do you mean using the softcfm and softerp params? I tried that and was unable to get it working as mentioned in the link to the other question, so I thought that using mud plugin would be another of approaching this problem.

lonewolf gravatar imagelonewolf ( 2016-06-22 14:40:36 -0600 )edit