simple_gripper.sdf

<?xml version="1.0"?>
<sdf version="1.7">
  <!-- Note: This is the accompanying SDF file for the example demo in
       simple_gripper.cc and deformable_box.cc and therefore these files must
       be kept in sync.

       This file defines the model for a simple gripper having two fingers on
       prismatic joints. Only the left finger is actuated. The modeler will want
       to add a coupler constraint between the fingers (if the selected solver
       supports it) or simply lock the right finger in place.

       The frame of the gripper, G, has its x-axis pointing to the right
       of the gripper, its y-axis pointing "forward" (towards the fingers
       side) and, the z-axis pointing upwards. This file only defines visual
       geometry but not contact geometry, allowing the demo in
       simple_gripper.cc to add contact geometry programmatically.

       simple_gripper.cc adds pads to the model programmatically. Including the
       thickness of these pads, 6 mm, and the offset from the center of the
       corresponding finger, 4.6 mm, each finger is positioned along the x-axis
       such that at q=0 the pads from each finger barely touch. This is 6 mm +
       4.6 mm = 10.5 mm.
  -->
  <model name="simple_gripper">
    <!-- Pose X_WG of the gripper model frame G in the world frame W. -->
    <pose>0.0555 0 0.0505 0 0 1.57</pose>
    <joint name="weld_base" type="fixed">
      <parent>world</parent>
      <child>y_translate_link</child>
    </joint>
    <link name="y_translate_link">
      <inertial>
        <mass>0.0001</mass>
        <inertia>
          <ixx>0.0001</ixx>
          <ixy>0</ixy>
          <ixz>0</ixz>
          <iyy>0.0001</iyy>
          <iyz>0</iyz>
          <izz>0.0001</izz>
        </inertia>
      </inertial>
    </link>
    <joint name="translate_joint" type="prismatic">
      <parent>y_translate_link</parent>
      <child>body</child>
      <axis>
        <xyz expressed_in="__model__">0 0 1</xyz>
        <!-- Drake attaches an actuator to all joints with a non-zero effort
             limit. We do want an actuator for this joint. -->
        <limit>
          <effort>500</effort>
        </limit>
      </axis>
    </joint>
    <link name="body">
      <pose>0 -0.049133 0 0 0 0</pose>
      <inertial>
        <mass>0.988882</mass>
        <inertia>
          <ixx>0.162992</ixx>
          <ixy>0</ixy>
          <ixz>0</ixz>
          <iyy>0.162992</iyy>
          <iyz>0</iyz>
          <izz>0.164814</izz>
        </inertia>
      </inertial>
      <visual name="visual">
        <geometry>
          <box>
            <size>0.146 0.0725 0.049521</size>
          </box>
        </geometry>
        <material>
          <diffuse>0.3 0.3 0.3 0.9</diffuse>
        </material>
      </visual>
    </link>
    <link name="left_finger">
      <!-- Each finger is positioned along the x-axis such that at q=0 the pads
      of each finger barely touch each other. See notes at the top of this
      file. -->
      <pose>-0.0105 0.029 0 0 0 0</pose>
      <inertial>
        <mass>0.05</mass>
        <inertia>
          <ixx>0.16</ixx>
          <ixy>0</ixy>
          <ixz>0</ixz>
          <iyy>0.16</iyy>
          <iyz>0</iyz>
          <izz>0.16</izz>
        </inertia>
      </inertial>
      <visual name="visual">
        <geometry>
          <box>
            <size>0.007 0.081 0.028</size>
          </box>
        </geometry>
        <material>
          <diffuse>0.3 0.3 0.3 0.9</diffuse>
        </material>
      </visual>
    </link>
    <link name="right_finger">
      <!-- Each finger is positioned along the x-axis such that at q=0 the pads
      of each finger barely touch each other. See notes at the top of this
      file. -->
      <pose>0.0105 0.029 0 0 0 0</pose>
      <inertial>
        <mass>0.05</mass>
        <inertia>
          <ixx>0.16</ixx>
          <ixy>0</ixy>
          <ixz>0</ixz>
          <iyy>0.16</iyy>
          <iyz>0</iyz>
          <izz>0.16</izz>
        </inertia>
      </inertial>
      <visual name="visual">
        <geometry>
          <box>
            <size>0.007 0.081 0.028</size>
          </box>
        </geometry>
        <material>
          <diffuse>0.3 0.3 0.3 0.9</diffuse>
        </material>
      </visual>
    </link>
    <joint name="left_slider" type="prismatic">
      <parent>body</parent>
      <child>left_finger</child>
      <axis>
        <xyz>1 0 0</xyz>
        <!-- Drake attaches an actuator to all joints with a non-zero effort
             limit. We do want an actuator for this joint. -->
        <limit>
          <effort>500</effort>
        </limit>
      </axis>
    </joint>
    <joint name="right_slider" type="prismatic">
      <parent>body</parent>
      <child>right_finger</child>
      <axis>
        <xyz>1 0 0</xyz>
        <!-- Drake attaches an actuator to all joints with a non-zero effort
             limit. We do NOT want an actuator for this joint. -->
        <limit>
          <effort>0</effort>
        </limit>
      </axis>
    </joint>
  </model>
</sdf>