Actuator

A mover helps a machine work.

It can push or turn things. This mover needs energy to work. It can use air or power. It can even use liquid.

Some movers use heat to move. Others use magnets to pull. Some movers are soft like muscles. They can change shape easily. This helps them work safely near people.

These movers make many tools work well.

An actuator is a part of a machine that makes it move. You can think of it as a "mover." It takes a small signal and turns it into force or motion.

To work, an actuator needs a source of power. This power can come from many places.

Some use liquids, like oil, to push parts. We call these hydraulic actuators. Since liquids do not squash easily, they can push with great force. Others use gas, like air. These are called pneumatic actuators.

They are often simpler than hydraulic ones.

Many machines use electric actuators. These use electric motors to create motion. Some turn in a circle. This is called rotary motion. Others move in a straight line. This is called linear motion.

Some special ones use heat to bend or move. There are even soft actuators. These are made of flexible materials. They can change shape like human muscles. This helps them work safely near people.

An actuator is a special part of a machine that acts as a "mover." Its main job is to turn a small signal into mechanical energy. This energy can create force, torque, or movement.

To do this, an actuator needs two things. First, it needs a control device to send a signal. Second, it needs a source of energy to do the work. The signal might be a small amount of electricity or even human power. The energy can come from air, liquids, or electricity.

There are many ways these movers work step by step. In a hydraulic actuator, a liquid like oil is used. The pressure of the liquid pushes a piston inside a tube. This makes the piston move in a straight line or a circle.

Because liquids do not squash easily, they can push with huge force. Pneumatic actuators work in a similar way, but they use gas like air. These are often simpler because they do not need complex pipes to recycle the fluid. Some even use steam to create motion in old locomotives.

Electric actuators are very common in modern machines. These often use an electric motor to create torque, which is a twisting force.

An electromechanical actuator, or EMA, uses parts like a screw to turn that twist into straight movement. These are very accurate and do not need much maintenance. Some electric motors are designed to move in a circle, which is called rotary motion. Others are designed to move in a straight line, called linear motion. A linear motor can be thought of as a rotary motor that has been unrolled.

Scientists and engineers have developed many types of these tools over time. Since 1960, many new technologies for actuators have appeared.

For example, some actuators use heat to make parts bend. This is how a thermostat works to control temperature. Other actuators use magnets to pull parts together. There are even "soft actuators" made of flexible materials like polymers. These are designed to act more like human muscles for use in healthcare.

You can see these movers working in many places every day. Rotary actuators are used to move the arms of industrial robots. Linear actuators are used in very precise jobs like making watches or medicines.

Even a grandfather clock uses a mechanical actuator to strike the hours. Whether it is a tiny part in a phone or a large part in a construction machine, actuators make automation possible. They turn simple signals into the physical actions that power our world.

An actuator is a critical component in a machine that produces force, torque, or displacement. It acts as a transducer, which is a device that converts one form of energy into another. Specifically, an actuator translates a stimulus, such as an input signal, into mechanical energy. This process allows a system to perform physical work in a controlled way. To function, every actuator requires two essential elements: a control device and a source of energy. The control device provides a relatively low-energy signal, such as voltage or fluid pressure. The energy source provides the actual power needed to create movement.

Actuators are often classified by the type of energy they use to create motion. Hydraulic actuators use the pressure of a liquid, typically oil, to move a piston inside a tube. This can result in linear, rotary, or oscillatory motion. Because liquids are nearly impossible to compress, these actuators can exert massive amounts of force. In a single-acting actuator, fluid pressure is applied to only one side of the piston. In a double-acting actuator, pressure is applied to both sides to drive the return stroke.

Pneumatic actuators function similarly to hydraulic ones but use gas, usually air, instead of liquid. These systems are often less complicated because they do not require pipes to recycle the working fluid. However, they still require external infrastructure like compressors, reservoirs, and filters. Historically, steam pressure was used in early steam engines and locomotives to drive pneumatic actuators. This created a reciprocating motion that was converted into rotary motion via a crankshaft. While pneumatics are common, they are sometimes less convenient than electrical systems due to this required infrastructure.

Electric actuators have seen significant technological development since 1960. An electric actuator typically uses a motor to generate torque, or a twisting force. This torque is then converted into the required mechanical motion. One specific type is the electromechanical actuator, or EMA. An EMA uses mechanical parts like a toothed belt or a screw to turn rotational force into linear movement. These devices are highly accurate and require little maintenance. They can even reach high forces, sometimes on the order of 100 kN.

Linear and rotary motions represent the two primary ways an actuator moves. A rotary actuator uses a motor to turn a part through an angle, sometimes up to 360 degrees. These are widely used in industrial robotic arms and motion control systems. In contrast, a linear actuator produces movement along a straight path. A linear electric motor can be imagined as a rotary motor that has been cut and unrolled. These motors are highly versatile for low-load tasks, such as those requiring up to 30 kg of force. They offer high precision, often equal to or less than 0.1 mm, and high cycling rates exceeding 100 cycles per minute.

Beyond electricity and fluids, other physical properties can drive an actuator. Thermal actuators use heat to cause expansion in solid materials. For example, a thermostat might use a strip of two different metals that bends when heated. Magnetic actuators use external magnetic fields to attract ferromagnetic materials.

There is also a growing field of soft actuators. These are made from flexible materials like polymers or liquids. Unlike rigid industrial actuators, soft actuators are designed to be biocompatible and adaptable. This makes them ideal for use in healthcare and human-centered robotics.

Modern manufacturing is changing how these advanced devices are built. Many soft actuators are currently made using complex, manual processes like micro-moulding or mask lithography. To make this faster and cheaper, researchers are using 3D printing for rapid prototyping. This allows for the creation of shape-memory polymer (SMP) actuators. These materials can respond to light, heat, moisture, or magnetic fields through a process called the shape memory effect. This technology helps bridge the gap between complex design and practical implementation in science and medicine.