impedancecontrol

Impedance control is a robotics technique in which the interaction dynamics at a robot’s end effector are shaped by a defined mechanical impedance, typically modeled as a mass-spring-damper. Instead of forcing exact motion, the controller aims for compliant, stable contact with uncertain environments. The approach was introduced by Neville Hogan in the 1980s.

The end-effector force F is modeled as F = M a + B v + K x, with a acceleration, v velocity, x displacement, and M, B, K the desired inertia, damping, and stiffness. Choosing these parameters makes the robot behave like a virtual impedance during contact.

Impedance control is implemented through torque or position loops, and is closely related to admittance control, which inverts the relationship and commands motion from measured forces. Cartesian impedance control applies the model in Cartesian space to manage interactions with objects.

Applications include manipulation with uncertain contact, assembly tasks, teleoperation, haptics, and certain surgical robotics scenarios.

Advantages include safer, more robust interaction and tolerance to modeling errors; limitations involve parameter tuning, sensor noise, delays, and trade-offs between responsiveness and stability.

See also: admittance control, force control.