These motors are integral components of motor-and-controller systems designed for extreme accuracy in positioning and speed control. Common applications include computer-controlled manufacturing machines and process equipment. Servomotors represent the largest category of motors for precision motion control, available in AC, DC brush-type, and brushless DC versions.
Closed-loop control systems, commonly used with servomotors, employ feedback devices to provide information to a digital controller that drives the motor. In some configurations, a tachometer may be utilized for velocity control while an encoder provides position information. Alternatively, a resolver can supply both position and velocity feedback data.
Step (or stepper) motors, which move in fixed increments rather than rotating continuously, provide another method for precision motion control. Typically, these operate as part of open-loop control systems without feedback devices.