Hardware

Elastic Actuation

Elastic Actuation is the deliberate introduction of compliance, typically a spring, between an actuator's gearbox and its load. The canonical form is the series elastic actuator, introduced by Pratt and Williamson in 1995, in which measuring spring deflection turns force control into a position-sensing problem, providing clean force regulation, shock tolerance, and energy storage. Variable stiffness actuators extend the idea with mechanically adjustable compliance.

Why it matters for physical AI

Compliance protects gearboxes from impact and makes physical human-robot contact intrinsically safer, which is why elastic actuation appears in exoskeletons, legged robots, and collaborative platforms designed to work around people.