Glossary · Robotics
Joint axis
Also known as: Robot axis, Joint
German: Gelenkachse
In robotics, a joint axis is the axis about which a revolute joint rotates or along which a prismatic joint slides, driven by its own motor and measured by its own encoder. The positions of all joint axes together define the robot's configuration.
- Robotics
In one sentence
A joint axis is the rotation or sliding axis of one robot joint, with its own drive and encoder; together they define the robot pose.
Example
The operator jogs joint axis 4 by 10 degrees to free the wrist cable before moving the robot in the Cartesian frame.
How it applies
- Engineering: Each joint axis has a range, maximum speed and torque. Software and, where needed, mechanical limits restrict the range; safety-rated axis limiting can reduce the space the robot occupies.
- Operation: Jogging in joint mode moves one axis at a time, which is useful near a Singularity or to recover from a collision. Axes are usually numbered from the base (A1 or J1) outward.
- Documentation: The documentation team should use the controller's axis naming, show the positive rotation direction of each axis in a drawing, and list axis ranges and speeds in the technical data. Rotary motion hazards near the joints belong in the safety chapter.
Joint axis vs. Cartesian axis
A joint axis belongs to the robot's mechanics. Cartesian axes (X, Y, Z and rotations) belong to a coordinate system such as the Base coordinate system. Jogging in Cartesian mode moves several joint axes at once.