Control

Steady-State Error

Steady-state error is the residual difference between a control system's output and its reference as time goes to infinity, after transients have decayed. Its magnitude depends on system type and input class: a type-1 system has zero steady-state error to a step but finite error to a ramp, and integral action in PID control is the standard mechanism for eliminating constant offsets. Persistent disturbances such as gravity loading produce steady-state error unless compensated.

Why it matters for physical AI

A gripper that settles two millimeters from its target misses the grasp; integral compensation and gravity feedforward exist precisely to drive this error to zero on real arms.