Stepper Motor

A motor that turns a fixed angle per pulse, so it can be positioned open-loop without an encoder.

A stepper motor divides one full turn into a fixed number of steps — commonly 1.8° per step, or 200 steps per revolution. Each pulse from the driver advances the rotor by exactly one step, so the controller always knows the motor's position just by counting pulses; that lets it run open-loop, with no position feedback, and keeps cost low. That makes steppers common in 3D printers, desktop CNC mills, and some low-cost desktop robot arms. The downside is that torque falls off sharply as speed rises, and if the load is too high the motor can silently “skip steps” without the controller noticing; a stepper also draws current and heats up even while just holding still. Robot joints that need force control, back-drivability, or fast dynamic response generally use a servo setup instead — a brushless motor paired with an encoder.

ExampleThe X, Y, and Z axes and the extruder of a desktop 3D printer are usually all driven by stepper motors.

Also called

Stepping Motor

Related

Servo Motor · Brushless DC Motor · Rotary Encoder · Open-loop Control · Desktop Robot Arm · Position Control

Sources

Stepper motor - Wikipedia