API review

Proposer: John Hsu

Present at review:

• List reviewers

Changes

The ability to specify Joints without specifying Links.

Original URDF Proposal:

  <link name="C">
    <joint name="J" type="revolute">

      <!-- transform from link to joint frame -->
      <!-- in old URDF, this is undefined and assumed to be identity transform -->
      <origin xyz="0 0 0" rpy="0 0 0"/> 

      <!-- joint properties -->
      <axis xyz="0 1 0"/>  <!--in the joint frame-->

      <parent name="P"/>  <!-- in old URDF, this is in <link> not in <joint> -->
        <!-- <origin> is the transform from Joint Frame to Parent  Link -->
        <!-- in old URDF, this is in <link> not in <joint><parent> -->
        <origin xyz="0 0 0" rpy="0 0 0"/> 
      </parent>

      <joint_properties damping="1" friction="0"/>
      <limit lower="0.9" upper="2.1" effort="1000" velocity="1"/>
      <safety_controller soft_lower_limit="0.7" soft_upper_limit="2.1" k_position="1" k_velocity="1" />
      <calibration reference_position="0.7" />
    </joint>

    <inertial>
      <mass value="10"/>
      <origin xyz="0 0 0" rpy="0 0 0"/>
      <inertia ixx="1" ixy="0" ixz="0" iyy="1" iyz="0" izz="1"/>
    </inertial>

    <visual>
      <origin xyz="0 0 0" rpy="0 0 0"/>
      <geometry>
        <box size="1 1 1"/>
      </geometry>
      <texture name="PR2/Green"/>
    </visual>

    <collision>
      <origin xyz="0 0 0" rpy="0 0 0"/>
      <geometry>
        <box size="1.01 1.01 1.01"/>
      </geometry>
      <contact_coefficient mu="0"  resitution="0"  k_p="0"  k_d="0" />
    </collision>
  </link>

New URDF Proposal:

  <joint name="J" type="revolute">
    <dynamics damping="1" friction="0"/>
    <limit lower="0.9" upper="2.1" effort="1000" velocity="1"/>
    <safety_controller soft_lower_limit="0.7" soft_upper_limit="2.1" k_position="1" k_velocity="1" />
    <calibration reference_position="0.7" />

    <axis xyz="0 1 0"/> 

    <parent link="P">
      <origin xyz="0 0 0" rpy="0 0 0"/> 
    </parent>

    <child link="C">
      <origin xyz="0 0 0" rpy="0 0 0"/> 
    </child>
  </joint>

  <link name="C">
    <inertial>
      <mass value="10"/>
      <origin xyz="0 0 0" rpy="0 0 0"/>
      <inertia ixx="1" ixy="0" ixz="0" iyy="1" iyz="0" izz="1"/>
    </inertial>

    <visual>
      <origin xyz="0 0 0" rpy="0 0 0"/>
      <geometry>
        <box size="1 1 1"/>
      </geometry>
      <texture name="PR2/Green"/>
    </visual>

    <collision>
      <origin xyz="0 0 0" rpy="0 0 0"/>
      <geometry>
        <box size="1.01 1.01 1.01"/>
      </geometry>
      <contact_coefficient mu="0"  resitution="0"  k_p="0"  k_d="0" />
    </collision>
  </link>

• Making joint frame the same as link frame,

    <joint name="J" type="revolute">
      <dynamics damping="1" friction="0"/>
      <limit lower="0.9" upper="2.1" effort="1000" velocity="1"/>
      <safety_controller soft_lower_limit="0.7" soft_upper_limit="2.1" k_position="1" k_velocity="1" />
      <calibration reference_position="0.7" />
  
      <!-- origin: origin of the joint in the parent frame -->
      <!-- child link frame is the joint frame -->
      <!-- axis is in the joint frame -->
      <origin xyz="0 0 0" rpy="0 0 0"/> 
      <axis xyz="0 1 0"/> 
      <parent link="P"/>
      <child link="C"/>
  
    </joint>
  
    <link name="C">
      <inertial>
        <mass value="10"/>
        <origin xyz="0 0 0" rpy="0 0 0"/>
        <inertia ixx="1" ixy="0" ixz="0" iyy="1" iyz="0" izz="1"/>
      </inertial>
  
      <visual>
        <origin xyz="0 0 0" rpy="0 0 0"/>
        <geometry>
          <box size="1 1 1"/>
        </geometry>
        <material name="Green"/>
      </visual>
  
      <collision>
        <origin xyz="0 0 0" rpy="0 0 0"/>
        <geometry>
          <box size="1.01 1.01 1.01"/>
        </geometry>
        <contact_coefficient mu="0"  resitution="0"  k_p="0"  k_d="0" />
      </collision>
    </link>
  
    <material name="Green">
      <texture filename="...texture file..." />
      <!--color rgb="255 255 255" /-->
    </material>

Question / concerns / comments

Enter your thoughts on the API and any questions / concerns you have here. Please sign your name. Anything you want to address in the API review should be marked down here before the start of the meeting.

Meeting agenda

• <joint_properties> should be <dynamics>

• adding <mimic joint="Joint_name" offset="0" multiplier="1" /> under <joint>

• <rpy>: clearly define transform. make sure gazebo is doing rpy not ypr.

• check for cycles, flag unsupported feature error

• children should have weak_ptr pointer to parent links, use <boost::weak_ptr> and implement boost::shared_ptr<Link> GetParent()

• <joint><origin/></joint>: defines the origin of the joint in the parent frame

• child link frame is the joint frame
• axis is in the joint frame

• adding <material> blocks to URDF, with texture or color elements.

    <material name="Green">
      <texture filename="...texture file..." />
      <!--color rgb="255 255 255" /-->
    </material>

• get collada robot sample from Rosen (John)
• setup Euler Angles Reveiew (eric)

Conclusion

Package status change mark change manifest)

• Action items that need to be taken.

• Major issues that need to be resolved