An electromagnetic incremental-motion actuator which converts digital pulse inputs to analog output motion. The device is also termed a step motor. When energized in a programmed manner by a voltage and current input, usually dc, a step motor can index in angular or linear increments. With proper control, the output steps are always equal in number to the input command pulses. Each pulse advances the rotor shaft one step increment and latches it magnetically at the precise point to which it is stepped. Advances in digital computers and particularly microcomputers revolutionized the controls of step motors. These motors are found in many industrial control systems, and large numbers are used in computer peripheral equipment, such as printers, tape drives, capstan drives, and memory-access mechanisms.
Stepper motors are also used in numerical control systems, machine-tool controls, process control, and many systems in the aerospace industry. See also Computer graphics; Computer numerical control; Computer peripheral devices; Control systems; Digital-to-analog converter; Process control.There are many types of step motors. Most of the widely used ones can be classified as variable-reluctance, permanent-magnet, or hybrid permanent-magnet types. A variable-reluctance step motor is simple to construct and has low efficiency. The permanent-magnet types are more complex to construct and have a higher efficiency.
