Glossar

Actuators in robotics: drives explained simply

Nico Nuss 0
KI-generierte Symbolaufnahme einer Robotik-Präsentation mit einem kollaborativen Roboterarm und Greifer [Image content created with AI]

Actuatorsconvert control commands into a physical effect: they rotate, push, lift, open, close or change a force. In robotics, they are the “muscles” of a system. Sensors report what is happening; Actuators make the planned movement possible. Which type of drive makes sense depends on the task, load, precision, environment and energy supply – not on a blanket winner.

What are actuators?

Actuators are technical components or systems that convert electrical, hydraulic or pneumatic energy into mechanical movement or force. They therefore form the active element of many automated systems. While sensors collect information from the environment or about the state of a machine, actuators convert control commands into a physical action: such as opening a valve, turning a motor or moving a component.

In automation and control technology, actuators are the interface between digital control and real movement. Typical examples are electric motors, hydraulic cylinders, pneumatic cylinders, solenoid valves and piezo actuators. Without them, machines would not be able to carry out targeted movements. That is why they are indispensable in robotics, industrial systems, automotive technology, medical technology and building technology.

How do actuators work in a robotic system?

A robot works in a closed loop. The controller calculates a desired movement, the actuator generates the necessary force or movement, and sensors provide feedback on the result. Simplified, the chain is:

Control → power electronics or valve → actuator → mechanics → sensors → control

For example, an electric motor on the robot arm generates torque. A gearbox can adapt this torque and speed to the task, and a joint transfers the movement to the next arm section. Encoders, current measurement or force sensors then help the control system to check whether the joint is moving as planned. The basic contribution toProprioception in roboticsexplains this internal feedback in more detail.

The main types of actuators

Art Typical effect Common areas of application Important conflict of goals
Electric Rotary or linear movement Robot arms, mobile robots, grippers Controllability and integration in relation to power, heat and gear design
Hydraulic High linear or rotating forces Heavy machinery, mobile work equipment, special robotics Power density versus lines, maintenance and possible leakage
Pneumatic Fast, easy linear movement Grippers, handling, packaging Robustness and simple technology versus limited positioning
Piezoelectric Very small, quick adjustment Optics, precision positioning, microsystems Fine resolution versus small stroke and special control
Soft/yielding Deformation or yielding force transmission Soft robotics, wearables, sensitive objects Adaptability to complex modeling and control

Electric actuators

Electric motors are common in many stationary and mobile robots. You can create rotational movements directly; Linear movements can also be derived from this using a spindle, belt or gear. Servo drives combine motors, power electronics and feedback to move to position, speed or torque in a controlled manner. This makes them attractive for repeatable robotics tasks. The article explains how electric and hydraulic drives differ in roboticsElectric vs. hydraulic actuatorsa. For additional context, see What Is Samsung’s Robotics Strategy?.

Hydraulic actuators

Hydraulics uses pressurized fluid to power cylinders or hydraulic motors. It is particularly relevant where high forces, robust components or heavy loads are required. However, the entire system requires, among other things, a pump, lines, valves and a clean maintenance strategy. Whether hydraulics are the right choice depends on the application and not just on the available power.

Pneumatic actuators

Pneumatics uses compressed air. Cylinders and grippers are practical in many industrial environments when simple movements need to be carried out quickly and robustly. Air is compressible; this influences the dynamic behavior and makes high-precision positioning more demanding than with some electrical solutions. Pneumatics are still useful for many opening/closing or handling tasks.

Piezo and other special actuators

Piezo actuators convert electrical voltage into very small material deformations. Their strength lies in fine movements and short reaction times, not in the long travel distance. There are also shape memory, magnetic or electrostatic actuators. Their suitability depends heavily on scale, required stroke, force, environment and control.

Actuator and sensor: what’s the difference?

A sensor measures; an actuator works. A temperature sensor provides a measured value and a valve actuator can change the flow. An encoder reports the position of a robot arm and a motor moves it. Both work together in a functioning automation system. The terms are therefore not interchangeable, even if individual modules – such as a servo with encoder – can closely connect drive and feedback.

Especially with oneManipulator in roboticsThis interaction becomes visible: actuators move the joints, sensors support the control system in recording position, speed and, if necessary, forces. For a complementary technical perspective, see Investment Guide 2026: The best ETFs and stocks for robotics.

What is important when choosing?

The selection does not begin with the question of the most modern type of drive, but with the task. The main criteria are:

  • Movement type:Is rotary or linear movement required? How large must the stroke and angular range be?
  • Power, torque and dynamics:What load is realistic, how quickly should it be moved or held?
  • Precision and control:What positioning and repeatability accuracy does the process require, what sensors are available?
  • Vicinity:Dust, humidity, clean room, temperature and noise limits influence the design.
  • Integration:Weight, installation space, energy supply, cables, safety and maintenance are part of the decision.

In robotics, actuation is the ability to create movement and manipulation. The introduction ofEngineering LibreTextsclassifies both tasks as interrelated effects of a robot. For the technical definition of a mechatronic actuator is theBasics page on mechatronic actuatorsa resilient addition.

Actuators in humanoid robots and wearables

Humanoid robotsand wearable robotics pose special requirements. Actuators in legs and arms often not only have to move to a position, but also react flexibly to contact, load changes or an unexpected movement. This can be supported via mechanics, control and suitable sensors. A high number of joints creates movement options, but increases the requirements for drive, energy supply and coordination. The article explains the connection to mobilityDegrees of Freedom (DoF). For a broader industry perspective, see Gemini Robotics Controls Apollo: What the Humanoid Demo Means.

When it comes to wearables and soft robotics, the focus is often not on maximum rigidity, but rather on safe, ergonomic power transmission. Therefore, compliant mechanisms and flexible actuators are interesting approaches. However, they do not replace the careful design of the entire system.

Conclusion: Actuators make robots move

Actuators translate control commands into force and movement. Electric, hydraulic, pneumatic, piezoelectric and compliant solutions each have different strengths and limitations. Good robotics is not created by an actuator alone, but rather by the interaction of mechanics, energy supply, sensors, control and a safety consideration that is appropriate to the application.

Frequently asked questions about actuators

What is an actuator simply explained?

An actuator is a component that converts a control command into a physical effect, for example rotation, movement or force.

What is the difference between actuator and sensor?

A sensor records measured values. An actuator creates an effect, such as movement or force. In control loops, sensors provide feedback while actuators execute the controller’s commands.

What types of actuators are there?

Electric, hydraulic, pneumatic and piezoelectric actuators are common. Soft robotics also uses compliant and flexible drive principles. For a market-level comparison, the Robotics Atlas provides a structured overview of manufacturers and platforms.

Why are electric actuators common in robots?

Electric motors can be easily combined with power electronics, sensors and digital control. Whether they are suitable still depends on the load, dynamics, environment and design.

When are hydraulic actuators used?

Hydraulic actuators are used, among other things, for high forces and heavy loads. You need a suitable hydraulic system with components such as pumps, lines and valves.

Are actuators just motors?

No. Motors are an important form of actuator. Cylinders, valves, piezo elements and other components can also convert energy into a controllable physical effect.

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