<contact> element

This element describes a contact attached to the robot body.

Here is a example of the contact element:

   1   <contact name="l_sole_contact" link="l_sole">
   2     <origin xyz="0 0 0" rpy="0 0 0" />
   3     <geometry>
   4       <box size="0.05 0.05 0.05" />
   5     </geometry>
   6     <limit normal_force="400" />
   7   </contact>

Attributes

• name (required)

  • The name of the contact itself

• link (required)

  • The name of the link on which the contact is attached.

Elements

• <origin> (optional: defaults to identity if not specified)

  • The reference frame of the visual element with respect to the reference frame of the link.

    xyz (optional: defaults to zero vector)

    • Represents the offset.

    rpy (optional: defaults to identity if not specified)

    • Represents the fixed axis roll, pitch and yaw angles in radians.

  <geometry> (required)

  • The shape of the visual object. This can be one of the following:

  • <box>

    • size attribute contains the three side lengths of the box. The origin of the box is in its center.

    • Contact is considered valid when the reaction force is going toward the box interior.
      • surface, going toward the outside.

    <cylinder>

    • Specify the radius and length. The origin of the cylinder is in its center.

    • Contact is considered valid when the reaction force is going toward the cylinder interior.

    <sphere>

    • Specify the radius. The origin of the sphere is in its center.

    • Contact is considered valid when the reaction force is going toward the sphere interior.

    <mesh>

    • A trimesh element specified by a filename, and an optional scale that scales the mesh's axis-aligned-bounding-box. The mesh file is not transferred between machines referencing the same model. It must be a local file.

    • Contact is considered valid when the reaction force is collinear with the surface normal and of opposite direction.

  <limit> (optional)

  • Limitations to take into consideration when the contact is active.

    normal_force (optional)

    • Maximum reaction force allowed in this contact zone. Balance and robot integrity is not guaranteed if a larger force is applied.