adminACTUATORS
Actuators are devices that convert energy into motion. The motion may be linear or rotary activated by a power source. The actuator is made of two main parts, the signal amplifier and the transducer. The amplifier converts the low power s input signal into a high power output signal before it is fed into the transducer. The transducer then converts the energy of the amplified control signal to do work. Thus, actuators in their function react to an input energy source, (such as an electrical, hydraulic, thermal etc.) converting the input energy into mechanical motion or energy. The actuator movement continuously controlled and monitored by sensors and feedback mechanisms, to ensure precise and accurate motion.
Actuators are classified according to their input energy source, these may include; mechanical, electrical, hydraulic and pneumatic, thermal, ultrasonic, and electronic actuators.
Mechanical actuators use mechanical energy in devices like, racks, gears, links and joints to convert energy into mechanical motion. For example a screw jack uses mechanical energy to provide enough force or energy to lift up a car.
Electrical actuators use electrical energy in devices like electric motors and others to convert electrical energy into mechanical energy or motion. Electrical actuators comprise the following; the drive system which is usually an electric motor and a switching device, which is either a mechanical switch (e.g. solenoid, relay) or a solid state switch (e.g. diode, thyristor, transducer etc.). For example an electric actuator upon receiving a control signal from a switch responds by converting the electrical energy in the motor into mechanical motion. For instance, an electric motor uses electrical energy to create a rotational movement to turn an object or move the object.
Hydraulic and pneumatic actuators uses fluid and air pressure respectively to convert energy into motion. Hydraulic and pneumatic actuators are normally either rotary motors or linear pistons and cylinders. They are ideally suited for generating very large force coupled with large motions. Pneumatic actuators use compressed air and are more suited for low to medium force, pressure and high speed applications. Hydraulic actuators use oil under pressure which is incompressible. They are best suited for high pressure or power and low speed application.
Thermal actuators use thermal energy to produce motion or force. Examples are thermal expansion and contraction actuators (bimetallic strip), shape memory alloys (SMA) and thermoelectric actuators.
Ultrasonic actuators use high frequency sound waves to produce motion or force. Example of these are; ultrasonic motors, ultrasonic piezoelectric actuators and ultrasonic shape memory alloys.
Electronic actuators use electronic signals to produce motion or force, through electronic switches like diodes, thyristors etc. for example the electronic throttle control actuators used in automotive applications.
The benefit of using actuators in machines, equipment and devices cannot be overemphasized: the use of actuators enables t remote operations, by the amplification of input signals to the desired output to activate it. Besides this, actuators provide for precise control over motion, allow fast response time, greater reliability, ample flexibility and durability in their operation.
The main drawbacks in the use of actuators are the complexity in their design features, high cost and sensitivity to the operating environment.
Actuators find application in a wide range of industries, for instance: actuators are used in robotics to control the movement of robotic arms, legs and other components. Actuators are also used in automation and industrial automation systems to control the movement of machines, equipment and devices such as conveyor belts, pumps and valves. Actuators are used in automotive applications or systems to control the movement of the vehicle components such as doors, windows and seat. Finally actuators are used in smart phones, computers and gaming consoles to activate many parts of their system components.
The future of actuators in design is steering in the following directions: increased use of advanced materials such as nanomaterial, smart materials, miniaturization of actuator components, and the integration of actuators to the internet of thing infrastructure. This future development is expected to make actuators more efficient, requiring low energy and optimized actuator control systems.
SOURCES:
- Actuators: fundamentals, types and applications by Sergejus Ivanikovas.
- Actuators technology by George A. Fontaine.
- Robot actuators by Ryadi Aditya.
- Advanced actuator technologies by A.A Hernandez.
- Electromechanical actuators by Clarence W. de Silva.
