Actuator
Examples and applications
Examples and applications
-------------------------

In [engineering](/wiki/Engineering "Engineering"), actuators are frequently used as mechanisms to introduce [motion](/wiki/Motion "Motion"), or to clamp an object so as to prevent motion. In electronic engineering, actuators are a subdivision of transducers. They are devices which transform an input signal (mainly an [electrical signal](/wiki/Electrical_signal "Electrical signal")) into some form of motion.

### Examples of actuators

* [Comb drive](/wiki/Comb_drive "Comb drive")
* [Digital micromirror device](/wiki/Digital_micromirror_device "Digital micromirror device")
* [Electric motor](/wiki/Electric_motor "Electric motor")
* [Electroactive polymer](/wiki/Electroactive_polymer "Electroactive polymer")
* [Hydraulic cylinder](/wiki/Hydraulic_cylinder "Hydraulic cylinder")
* [Piezoelectric actuator](/wiki/Piezoelectric_actuator "Piezoelectric actuator")
* [Plasma actuator](/wiki/Plasma_actuator "Plasma actuator")
* [Pneumatic actuator](/wiki/Pneumatic_actuator "Pneumatic actuator")
* [Screw jack](/wiki/Screw_jack "Screw jack")
* [Servomechanism](/wiki/Servomechanism "Servomechanism")
* [Solenoid](/wiki/Solenoid_%28engineering%29 "Solenoid (engineering)")
* [Stepper motor](/wiki/Stepper_motor "Stepper motor")
* [Shape\-memory alloy](/wiki/Shape-memory_alloy "Shape-memory alloy")
* Thermal [bimorph](/wiki/Bimorph "Bimorph")
* [Hydraulic actuators](/wiki/Hydraulic_motor "Hydraulic motor")
* [Trim](/wiki/Trim_tab "Trim tab") actuator, in [aircraft design](/wiki/Aircraft_design_process "Aircraft design process")

### Circular to linear conversion

Motors are mostly used when circular motions are needed, but can also be used for linear applications by transforming circular to linear motion with a [lead screw](/wiki/Lead_screw "Lead screw") or similar mechanism. On the other hand, some actuators are intrinsically linear, such as piezoelectric actuators. Conversion between circular and linear motion is commonly made via a few simple types of mechanism including:
* [Screw](/wiki/Screw_%28simple_machine%29 "Screw (simple machine)"): [Screw jack](/wiki/Screw_jack "Screw jack"), [ball screw](/wiki/Ball_screw "Ball screw") and [roller screw](/wiki/Roller_screw "Roller screw") actuators all operate on the principle of the [simple machine](/wiki/Simple_machine "Simple machine") known as the screw. By rotating the actuator's nut, the screw shaft moves in a line. By moving the screw shaft, the nut rotates.
* [Wheel and axle](/wiki/Wheel_and_axle "Wheel and axle"): [Hoist](/wiki/Hoist_%28device%29 "Hoist (device)"), [winch](/wiki/Winch "Winch"), [rack and pinion](/wiki/Rack_and_pinion "Rack and pinion"), [chain drive](/wiki/Chain_drive "Chain drive"), [belt drive](/wiki/Belt_drive "Belt drive"), [rigid chain](/wiki/Rigid_chain_actuator "Rigid chain actuator") and [rigid belt](/wiki/Rigid_belt_actuator "Rigid belt actuator") actuators operate on the principle of the wheel and axle. By rotating a wheel/axle (e.g. [drum](/wiki/Cylinder_%28geometry%29 "Cylinder (geometry)"), [gear](/wiki/Gear "Gear"), pulley or [shaft](/wiki/Drive_shaft "Drive shaft")) a linear member (e.g. [cable](/wiki/Wire_rope "Wire rope"), rack, [chain](/wiki/Roller_chain "Roller chain") or [belt](/wiki/Belt_%28mechanical%29 "Belt (mechanical)")) moves. By moving the linear member, the wheel/axle rotates.

### Virtual instrumentation

In [virtual instrumentation](/wiki/Virtual_instrumentation "Virtual instrumentation"), actuators and sensors are the hardware complements of virtual instruments.


What mechanisms can be used to convert circular to linear motion?