Hardware

Stepper Motor

A stepper motor is an electric motor that rotates in discrete angular increments — commonly 200 full steps per revolution — by sequentially energizing stator windings, enabling open-loop position control without feedback sensors. Microstepping drivers subdivide steps for smoother motion and finer resolution. Steppers are inexpensive and hold position when stationary, but can silently lose steps under excess load, which is why 3D printers and low-cost robots use them while dynamic manipulators favor closed-loop servos.

Why it matters for physical AI

Cost-sensitive robot designs still lean on steppers for axes with predictable loads, and knowing their lost-step failure mode explains many calibration and drift issues in cheap hardware.