urdf

URDF Robot Models

(from Google Bard).

Code is XML.

Links

links

Joints

URDF (Unified Robot Description Format) defines six basic types of joints for constructing articulated robot models:

1. Fixed joint: This joint represents a rigid connection between two links, allowing no movement between them.

   <joint name="fixed_joint" type="fixed">
   	<parent link="base_link"/>
   	<child link="link1"/>
   	<origin xyz="0 0 0" rpy="0 0 0" />
   </joint>

2. Revolute joint: This joint represents a rotational joint around a single axis. It allows for one degree of freedom (DOF), enabling rotation about the specified axis.

   <joint name="revolute_joint" type="revolute">
   	<parent link="base_link"/>
   	<child link="link1"/>
   	<origin xyz="0 0 0" rpy="0 0 0" />
   	<axis xyz="0 0 1"/>
   	<limit lower="0" upper="${pi/2}" velocity="100" effort="100"/>
   </joint>

3. Prismatic joint: This joint represents a translational joint along a single axis. It allows for one DOF, enabling translation along the specified axis.

   <joint name="prismatic_joint" type="prismatic">
   	<parent link="base_link"/>
   	<child link="link1"/>
   	<origin xyz="0 0 0" rpy="0 0 0" />
   	<axis xyz="1 0 0"/>
   </joint>

4. Continuous joint: This joint is a variant of the revolute joint, allowing for unlimited rotation around the specified axis. It also provides one DOF.

   <joint name="continuous_joint" type="continuous">
   	<parent link="base_link"/>
   	<child link="link1"/>
   	<origin xyz="0 0 0" rpy="0 0 0" />
   	<axis xyz="0 0 1"/>
   </joint>

5. Planar joint: This joint allows for two DOFs, enabling translation in the plane defined by two axes and rotation about the perpendicular axis.

   <joint name="planar_joint" type="planar">
   	<parent link="base_link"/>
   	<child link="link1"/>
   	<origin xyz="0 0 0" rpy="0 0 0" />
   	<axis xyz="0 1 0"/>
   	<axis xyz="0 0 1"/>
   </joint>

6. Floating joint: This joint represents a six-DOF joint that allows for unrestricted movement in space. It is typically used to represent the base link of a robot, as it has no fixed reference point.

   <joint name="floating_joint" type="floating">
   	<parent link="base_link"/>
   	<child link="world"/>
   	<origin xyz="0 0 0" rpy="0 0 0" />
   </joint>