Glossary · Robotics
Impedance control
Also known as: Compliance control
German: Impedanzregelung
In robotics, impedance control is a control method that makes the robot respond to external forces like a programmable mass-spring-damper system: the controller sets the relationship between the force acting on the tool and the resulting deviation from the commanded position.
- Robotics
In one sentence
Impedance control makes a robot behave like an adjustable spring and damper, relating contact force to position deviation.
Example
With low stiffness set in impedance control, the robot yields when the worker pushes the gripper aside, then returns to its path when released.
How it applies
- Engineering: Impedance control is used for hand guiding, assembly with uncertain positions and contact tasks where a fixed force target is not practical. Stiffness and damping can be set per Cartesian direction, often requiring joint torque sensors or a wrist force/torque sensor.
- Commissioning: Too little damping makes the robot oscillate; too much stiffness makes contact hard. Parameters are tested with the real tool and workpiece.
- Documentation: The documentation team should explain in plain words what the parameters do (how soft or firm the robot feels), which values are validated for the application, and that impedance behavior is a control feature, not a safety-rated force limit unless the manufacturer declares it as a safety function.
Impedance control vs. force control
Force control regulates a target force. Impedance control regulates how position and force relate, so the robot yields in proportion to the force. Admittance control is a closely related variant used on position-controlled robots.