Actuators are components that convert energy into mechanical motion in order to move or control a mechanism or system. They rely on an energy source such as electrical current, hydraulic pressure or pneumatic pressure, and are activated by a control signal such as voltage, current, pressure or human exertion. Actuators can be found in many subsystems of unmanned aerial vehicles (UAVs) and other robotic vehicles.
Actuators may commonly be linear, converting energy into a straight line motion, or rotary, which use a servo or brushless motor to produce rotational motion and provide mechanical torque. Rotary actuators will either provide a limited angular stroke, or be capable of continuous rotation, which is useful for electro-optical targeting and other positioning and scanning systems on UAVs.
Actuators are also commonly used to move flight and attitude control surfaces on UAVs, such as the elevator, ailerons, flaps and nose wheel. Other unmanned aircraft applications include opening and closing the throttle valve on combustion engines, as well as doors and hatches.
Actuators can be combined with an electromagnetic clutch which can be manually engaged or disengaged. Such a system can be found in Optionally Piloted Vehicles (OPVs), allowing the pilot to switch between unmanned and manned flight modes.
For deep-sea and submersible applications, actuators can be housed in marine bronze or saltwater-resistant aluminium casings. These actuators are designed to operate under extremes of pressure and submersion and can be found on Remotely Operated Vehicles (ROVs), Autonomous Underwater Vehicles (AUVs) and other underwater robotics.
Actuation systems may provide redundancy by incorporating multiple motors, controllers, power sources and other components, thus creating a system architecture tolerant of single points of failure. These systems are important for safety-critical applications such as unmanned helicopters.