What is impedance control, and when is it advantageous in robotics?

• A. It shapes the force-motion relationship to be stiff.
• B. It uses only position feedback.
• C. It shapes the dynamic relationship between force and motion to achieve compliant interactions.
• D. It is the same as torque control.

Answer: (C)

Impedance control focuses on shaping how the end-effector responds to external forces by defining a desired relationship between force and motion, like a virtual mass–spring–damper. This makes the robot interact with its surroundings in a controlled, compliant way rather than locking rigidly to a trajectory.

This approach is especially useful when contact with the environment or with humans is likely. By tuning the virtual stiffness and damping, the robot can yield to forces, absorb impacts gently, and adapt to small positional or surface irregularities. That means safer, more reliable manipulation of delicate objects, easier human–robot collaboration, and smoother guiding or assembly tasks where exact force-free motion isn’t feasible.

In contrast, aiming for a stiff, rigid response (or relying only on position feedback) can cause high contact forces, instability, or damage during contact. Torque control alone doesn’t capture the intended force–motion relationship that impedance control explicitly prescribes.