Glossary · Motion control and drives
Inverse kinematics
Also known as: Backward kinematics, Reverse kinematics
German: Inverse Kinematik
In robotics and motion control, inverse kinematics is the calculation of the joint or axis positions that place the tool or end effector at a desired position and orientation. Depending on the kinematics, there may be several solutions, one, or none.
- Motion control
In one sentence
Inverse kinematics calculates the joint positions needed to put a robot's tool at a desired position and orientation.
Example
When a robot program specifies a Cartesian target, the controller uses inverse kinematics to find the six joint angles and picks the configuration set in the program.
How it applies
- Engineering: Six-axis robots usually have several solutions for one pose (for example elbow up or down). Programs store a configuration so the robot always chooses the same one.
- Commissioning: Near singularities, small Cartesian moves require very fast joint moves; controllers slow down or stop there.
- Operation: Linear moves through a singularity can fail with an error; joint moves avoid this.
- Documentation: Explain configurations and singularities in programming manuals with figures, and describe the error messages and recovery. Tell readers that unexpected joint motion near singularities is possible and must be considered when teaching near people.
Inverse vs. forward kinematics
Forward kinematics always has one answer: where the tool is for given joints. Inverse kinematics solves the opposite problem and may be ambiguous or unsolvable.