Hardware

Hysteresis

Hysteresis is the dependence of a system's output on its input history, producing different responses on loading versus unloading paths. In robots it appears as backlash and torsional wind-up in gearboxes, friction and stretch in tendon drives, and lag in sensors and elastomer-based tactile skins, introducing path-dependent errors that simple linear models cannot capture.

Why it matters for physical AI

Unmodeled hysteresis silently corrupts calibration, repeatability, and sim-to-real transfer, so identifying or learning these effects is often the difference between a policy working in simulation and on hardware.