A Guide to Actuators: Types of Actuators and How They Work
Have you seen a robot vacuum cleaner and how it moves in all directions on its own? Or have you ever used the stepper at the gymnasium? All these machines use actuators that enable them to move in their intended directions.
The truth is in today's world actuators are all around us, from access control systems on our doors to robots performing heavy lifting in various industrial plants. Even the silent versions of our cell phones include actuators that produce vibrations when they ring. Actuators are a part of many things that facilitates our everyday life and over the years actuators have shown their value and dependability in making our lives simpler, more convenient, and easier.
Although actuators play such a vital role in our everyday lives through the different types of machinery we use every day, you will rarely come across much information on actuators. Actuators are like no other device ever invented and our systems would collapse without them. But unlike some other machinery, we don’t give enough credit to actuators. So, if you are interested to know about these integral parts of machine systems and find out how they work, this blog will answer all your questions about actuators.
Let us dive in and find out what actuators are all about!
What are actuators?
Also aptly known as a ‘mover’ an actuator is a device that helps to move parts of a machine. It is usually powered by electricity or pressure, such as hydraulic or pneumatic and is an essential part of any machine that requires motion.
Actuators have been around for decades but still, find use in modern machinery. They remain an essential component in present-day automation and robotics. Actuators are also extensively used for machines in industries like agriculture, as well as in construction equipment. They are also widely used in industrial plants to control valves, fluid couplings, and other devices. Solar panels use actuators as well to follow the sun's movement so as to capture the solar energy most efficiently.
Actuators are part of household appliances and machinery too. In fact, actuators are found everywhere in our daily lives. For instance, they are used in smart home appliances like robot vacuum cleaners and ventilation fans, as well as small objects like electric switches and also in household devices like TV lifts and recliners. Even toys nowadays have actuators integrated into them. In short, the usage of actuators in our lives is almost endless.
How does an actuator work?
An actuator is a motor that converts energy into a force that moves or controls a machine or a system into which it has been assimilated.
Actuators enable movement by transforming incoming energy and signals into mechanical force which can be controlled and directed as per requirements. The outgoing motion can be either linear or rotational, and the input energy can be either electric, pneumatic (air), or hydraulic (water).
In essence, actuators for machines have a similar role to muscles in the human body. Actuators enable the machine to move, just like muscles help the leg, arm, fingers, and other body parts move.
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Types of actuators and how they are used
There are different kinds of actuators based on a number of factors, such as how they are powered, the kind of motion they initiate, and so on.
In this section, we will classify some of the most common actuators and the purpose we usually use them for.
Most common actuators in use:
1. Pneumatic actuators
Pneumatic actuators are powered by compressed gas and are used to create mechanical movement. They are a popular choice for many industries as they can make very precise movements and are cost-effective and powerful. Equipment that uses pneumatic actuators includes bus brakes, exercise machines, vane motors, pressure sensors, and more.
2. Hydraulic actuators
Hydraulic actuators are used to produce linear movements. They consist of a fluid-filled cylinder with a piston suspended at the centre, and a spring is attached to one end to help with the return motion. These actuators are widely used in exercise equipment like steppers, as well as for clamping and welding.
3. Electric actuators
Electric actuators convert electrical energy into mechanical energy. This is done by powering a motor which triggers certain components to move. Examples of electric actuators include electric motors, stepper motors, jack screws, and electric muscular stimulators used in robots.
4. Electromechanical actuators
Electromechanical actuators are used to transform electric signals into either rotary or linear motions, or both. These actuators are commonly found in healthcare equipment and manufacturing automation.
5. Electro-hydraulic actuators
Electrical power is used to give movement to a hydraulic accumulator, which then provides the force necessary to power heavy industrial equipment.
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Actuators as classified by the motion they initiate:
1. Linear actuators
Linear actuators are devices used to generate motion in a linear direction. They are commonly found in hydraulic and pneumatic equipment, both mechanical and electrical. Linear actuators are composed of a nut, cover, and sliding tube. The sliding tube provides the space for movement, while the nut and cover enable the interlocking motions.
While the history of the actuator dates back to the time of World War II (1938). The electric linear actuator as we know it today was invented by Bent Jensen only in 1979.
2. Rotary actuators
Rotary actuators are used to generate a circular movement. You may have seen them in action in your car's windshield wipers, your electric fan, or a factory machine transporting goods.
A rotary actuator and a linear actuator are often combined to move a machine in all four directions, i.e., forward, backward, up, or down.
Actuators as classified by the power source they utilise:
1. Thermal and magnetic actuators
Typically, thermal and magnetic actuators use shape-memory alloys that can be heated to produce the desired motion. It is also possible to generate motion by placing a coil in a static magnetic field. These actuators are lightweight and capable of producing a wide range of motions.
Mechanical actuators
The function of a mechanical actuator is to convert one kind of motion to another in order to achieve movement. This operates on the basis of a union between two structural elements like
pulleys and chains, gears and rails etc.
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Other types of actuators:
1. Supercoiled polymer actuators
Among the existing types of actuators, supercoiled polymer actuators are relatively new. They are used in robotics and prosthetic limbs as they can imitate the movement of the human muscle. Supercoiled polymer actuators function through a coil that contracts and expands depending on the energy they receive.
2. Soft actuators
Soft actuators are also a new addition to the list of actuators. They react to stimuli.
By adapting machines to environments, these actuators are mostly used for robotic versions of human applications and for human safety and health care initiatives.
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