Impedance Control

Key Insight

Position control fights the world: tell the arm to be at a spot and it will push arbitrarily hard to get there, snapping anything in the way. Impedance control instead commands a virtual spring-damper between the end-effector and a moving reference, so the arm pushes back gently in proportion to how far it has been displaced — you set the spring's stiffness, and that directly sets how much the arm yields under contact, its compliance. Pushing on the simulated arm and watching it give, then tuning the virtual stiffness from soft to stiff, is the core skill behind every contact-rich task: insertion, polishing, and working safely next to people.