gazebo_models/demo_joint_stiffness/model.sdf

<?xml version='1.0'?>
<sdf version='1.6'>
  <model name='demo_joint_stiffness'>
    <pose>0 0 0.06 0 0 0</pose>
    <link name='link_base'>
      <inertial>
        <mass>100</mass>
        <inertia>
          <ixx>1.2</ixx>
          <ixy>0</ixy>
          <ixz>0</ixz>
          <iyy>3.64</iyy>
          <iyz>0</iyz>
          <izz>4.6</izz>
        </inertia>
      </inertial>
      <gravity>1</gravity>
      <self_collide>0</self_collide>
      <kinematic>0</kinematic>
      <enable_wind>0</enable_wind>
      <visual name='visual_base'>
        <geometry>
          <mesh>
            <uri>model://demo_joint_stiffness/meshes/base_model.dae</uri>
            <scale>0.001 0.001 0.001</scale>
          </mesh>
        </geometry>
        <cast_shadows>1</cast_shadows>
      </visual>
      <collision name='collision_base'>
        <geometry>
          <box>
            <size>0.65 0.36 0.12</size>
          </box>
        </geometry>
      </collision>
    </link>
    <link name='link_high_stiffness'>
      <gravity>0</gravity>
      <pose>0.12 0 0.15 0.7853981633974483 0 0</pose>
      <inertial>
        <pose>0 0 0.12 0 0 0</pose>
        <mass>1</mass>
        <inertia>
          <ixx>0.0051</ixx>
          <ixy>0</ixy>
          <ixz>0</ixz>
          <iyy>0.0051</iyy>
          <iyz>0</iyz>
          <izz>0.0006</izz>
        </inertia>
      </inertial>
      <visual name='visual_high_stiffness'>
        <pose>0 0 -0.15 0 0 0</pose>
        <geometry>
          <mesh>
            <uri>model://demo_joint_stiffness/meshes/arm.stl</uri>
            <scale>0.001 0.001 0.001</scale>
          </mesh>
        </geometry>
        <material>
          <lighting>1</lighting>
          <script>
            <uri>file://media/materials/scripts/gazebo.material</uri>
            <name>Gazebo/Orange</name>
          </script>
        </material>
        <cast_shadows>1</cast_shadows>
      </visual>
    </link>
    <joint name='joint_high_stiffness' type='revolute'>
      <parent>link_base</parent>
      <child>link_high_stiffness</child>
      <pose>0 0 0 -0.15 0 0</pose>
      <axis>
        <xyz>1 0 0</xyz>
        <dynamics>
          <damping>0</damping>
          <friction>0</friction>
          <!-- Position where the link is vertical -->
          <spring_reference>-0.7853981633974483</spring_reference>
          <!--
               Spring stiffness coefficient
               The stiffness coefficient causes a torque (force for prismatic
               joints) to be applied based on the current joint position.
               At the spring_reference position no torque is applied.
               At any other position a torque is applied to the joint with a
               direction towards the spring_reference position.
               torque = spring_stiffness * (spring_reference - current_position)
          -->
          <spring_stiffness>7</spring_stiffness>
        </dynamics>
      </axis>
    </joint>
    <link name='link_medium_stiffness'>
      <gravity>0</gravity>
      <pose>0 0 0.15 0.7853981633974483 0 0</pose>
      <inertial>
        <pose>0 0 0.12 0 0 0</pose>
        <mass>1</mass>
        <inertia>
          <ixx>0.0051</ixx>
          <ixy>0</ixy>
          <ixz>0</ixz>
          <iyy>0.0051</iyy>
          <iyz>0</iyz>
          <izz>0.0006</izz>
        </inertia>
      </inertial>
      <visual name='visual_medium_stiffness'>
        <pose>0 0 -0.15 0 0 0</pose>
        <geometry>
          <mesh>
            <uri>model://demo_joint_stiffness/meshes/arm.stl</uri>
            <scale>0.001 0.001 0.001</scale>
          </mesh>
        </geometry>
        <material>
          <lighting>1</lighting>
          <script>
            <uri>file://media/materials/scripts/gazebo.material</uri>
            <name>Gazebo/Orange</name>
          </script>
        </material>
        <cast_shadows>1</cast_shadows>
      </visual>
    </link>
    <joint name='joint_medium_stiffness' type='revolute'>
      <parent>link_base</parent>
      <child>link_medium_stiffness</child>
      <pose>0 0 0 -0.15 0 0</pose>
      <axis>
        <xyz>1 0 0</xyz>
        <dynamics>
          <damping>0</damping>
          <friction>0</friction>
          <spring_reference>-0.7853981633974483</spring_reference>
          <spring_stiffness>0.7</spring_stiffness>
        </dynamics>
      </axis>
    </joint>
    <link name='link_low_stiffness'>
      <gravity>0</gravity>
      <pose>-0.12 0 0.15 0.7853981633974483 0 0</pose>
      <inertial>
        <pose>0 0 0.12 0 0 0</pose>
        <mass>1</mass>
        <inertia>
          <ixx>0.0051</ixx>
          <ixy>0</ixy>
          <ixz>0</ixz>
          <iyy>0.0051</iyy>
          <iyz>0</iyz>
          <izz>0.0006</izz>
        </inertia>
      </inertial>
      <visual name='visual_low_stiffness'>
        <pose>0 0 -0.15 0 0 0</pose>
        <geometry>
          <mesh>
            <uri>model://demo_joint_stiffness/meshes/arm.stl</uri>
            <scale>0.001 0.001 0.001</scale>
          </mesh>
        </geometry>
        <material>
          <lighting>1</lighting>
          <script>
            <uri>file://media/materials/scripts/gazebo.material</uri>
            <name>Gazebo/Orange</name>
          </script>
        </material>
        <cast_shadows>1</cast_shadows>
      </visual>
    </link>
    <joint name='joint_low_stiffness' type='revolute'>
      <parent>link_base</parent>
      <child>link_low_stiffness</child>
      <pose>0 0 0 -0.15 0 0</pose>
      <axis>
        <xyz>1 0 0</xyz>
        <dynamics>
          <damping>0</damping>
          <friction>0</friction>
          <spring_reference>-0.7853981633974483</spring_reference>
          <spring_stiffness>0.07</spring_stiffness>
        </dynamics>
      </axis>
    </joint>
    <allow_auto_disable>1</allow_auto_disable>
  </model>
</sdf>