actuation

Actuation is the action of causing a mechanism or system to move or operate by converting energy into mechanical energy. Actuators are devices that produce controlled motion or force, typically as part of a larger system such as a machine or robot.

Actuators come in several energy domains. Electrical actuators use electric motors to create torque or linear motion, or solenoids for linear force. Hydraulic actuators use pressurized fluid to generate high force and smooth motion, while pneumatic actuators use compressed air for faster, lighter actuation. Thermal actuators rely on thermal expansion or phase changes, magnetic actuators use magnetic fields, piezoelectric actuators exploit piezoelectric strain, and shape memory alloys change shape with temperature.

Performance is described by force or torque, speed or displacement, stroke, efficiency, and response time. Control can be open-loop, where motion is commanded without feedback, or closed-loop, where sensors and a controller correct errors. In practice, actuation systems are part of mechatronic assemblies that include sensors, controllers, and power electronics to achieve precise, repeatable motion.

Common applications include robotics, automation and manufacturing, aerospace and automotive systems, consumer electronics, and medical devices. Actuators are chosen based on required force, speed, travel, environment, and energy source, with consideration for reliability, size, heat, and safety. The field has rapidly evolved with micro- and nano-scale actuators in MEMS and the use of smart materials for adaptable actuation.