page_title: Rotary actuator
section_title: Stepper motors
hierarchical_section_title: Rotary actuator / Actuator power sources / Electric actuators / Stepper motors
caption_attribution_description: Stepping motors mainly from PCs
context_page_description: A rotary actuator is an actuator that produces a rotary motion or torque.
  The simplest actuator is purely mechanical, where linear motion in one direction gives rise to rotation. The most common actuators are electrically powered; others may be powered pneumatically or hydraulically, or use energy stored in springs.
  The motion produced by an actuator may be either continuous rotation, as for an electric motor, or movement to a fixed angular position as for servomotors and stepper motors. A further form, the torque motor, does not necessarily produce any rotation but merely generates a precise torque which then either causes rotation, or is balanced by some opposing torque.
context_section_description: Stepper motors are a form of electric motor that has the ability to move in discrete steps of a fixed size. This can be used either to produce continuous rotation at a controlled speed or to move by a controlled angular amount. If the stepper is combined with either a position encoder or at least a single datum sensor at the zero position, it is possible to move the motor to any angular position and so to act as a rotary actuator.
caption: A variety of stepper motors
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