Simple robot bounces when placed in world

asked 2014-10-31 01:20:31 -0600

site gravatar image

updated 2014-11-04 01:39:40 -0600

scpeters gravatar image

I have a simple structure that is a vertical pole connected to a horizontal pole at its top (forming an upside-down-L shape). A box hangs from the end of the horizontal pole. Since the structure isn't balanced, I added a joint between the body and the world to keep it from falling down. It doesn't fall down anymore, but now when I place it in the world it keeps bouncing up and down a small amount. Please let me know if you have any advice! Here's my model.sdf code:

<link name='body'>
  <pose>0 0 0 0 0 0</pose>
  <collision name='collision'>
    <geometry>
      <box>
        <size>.1 .1 3</size>
      </box>
    </geometry>
  </collision>

  <visual name='visual'>
    <geometry>
      <box>
        <size>.1 .1 3</size>
      </box>
    </geometry>
  </visual>

  <collision name='collision'>
    <pose>2.5 0 1.5 0 0 0</pose>
    <geometry>
      <box>
        <size>5 .1 .1</size>
      </box>
    </geometry>
  </collision>

  <visual name='visual'>
    <pose>2.5 0 1.5 0 0 0</pose>
    <geometry>
      <box>
        <size>5 .1 .1</size>
      </box>
    </geometry>
  </visual>

</link>

<link name='heavy_box'>
  <pose>5 0 2 0 0 0</pose>

  <collision name='collision'>
    <geometry>
      <box>
        <size>1 1 1</size>
      </box>
    </geometry>
  </collision>

  <visual name='visual'>
    <geometry>
      <box>
        <size>1 1 1</size>
      </box>
    </geometry>
  </visual>
</link>

<joint type="revolute" name="box_hinge">
  <pose>0 0 0 0 0 0</pose>
  <child>heavy_box</child>
  <parent>body</parent>
  <axis>
    <xyz>0 0 1</xyz>
    <limit>
        <lower>-0.001</lower>
        <upper>0.001</upper>
    </limit>
  </axis>
</joint>


<joint type="revolute" name="ground_hinge1">
  <pose>0 0 0 0 0 0</pose>
  <child>body</child>
  <parent>world</parent>
  <axis>
    <xyz>0 0 1</xyz>
    <limit>
        <lower>-0.001</lower>
        <upper>0.001</upper>
    </limit>
  </axis>
</joint>

</model>
</sdf>
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Comments

The model code is not complete. The pose of the model affects where the model is places in the world. I think, you are placing the model at (x,y,0) instead of (x,y,z), where z is the height at which the model should be so as not to cross the ground plane

Kunal Tyagi gravatar imageKunal Tyagi ( 2014-11-04 04:42:41 -0600 )edit