What is Actuator?

What is an Actuator?

An Actuator is a mechanical device that takes an input signal, typically electrical, and converts it into physical motion. In robotics, actuators are responsible for every movement a robot makes, from the rotation of arm joints to the opening and closing of grippers to the wheels that drive a mobile robot across a warehouse floor. Without actuators, a robot would be a motionless computer, capable of thinking but incapable of acting.

The term covers a broad family of devices, but they all share the same fundamental purpose: bridging the gap between digital commands and physical action. When a robot controller decides to move a joint by 45 degrees, it is an actuator that produces the torque and rotation needed to make that movement happen.

Types of Actuators in Robotics

Electric Motors

The most common actuators in modern robotics. Electric motors convert electrical energy into rotational motion and come in several varieties:

• Servo motors: Provide precise position, speed, and torque control through closed-loop feedback systems. They are the standard choice for industrial robot arms where accuracy is paramount.
• Stepper motors: Move in discrete steps, providing good position control without continuous feedback. Common in 3D printers, CNC machines, and lower-cost robotic systems.
• Brushless DC motors: Offer high efficiency, long life, and excellent speed control. Widely used in mobile robots, drones, and collaborative robots.
• Linear motors: Produce straight-line motion directly, without gears or belts to convert rotational motion. Used where high-speed linear positioning is needed.

Pneumatic Actuators

Use compressed air to produce motion. They excel at rapid, binary actions like opening and closing grippers and extending and retracting cylinders. Pneumatic systems are simple, cost-effective, and produce clean, fast action, making them popular in food processing and clean-room environments.

Hydraulic Actuators

Use pressurised fluid to generate very high forces in a compact package. Used in heavy-duty industrial robots, construction equipment, and applications where extreme lifting or pressing force is required. They offer the highest power-to-weight ratio of any actuator type.

Piezoelectric Actuators

Generate extremely small, precise movements by deforming a crystal when voltage is applied. Used in micro-robotics, precision positioning stages, and applications requiring nanometre-level accuracy.

Shape Memory Alloy Actuators

Materials that change shape when heated, returning to a predetermined form. Used in soft robotics and biomedical devices where conventional motors are too bulky or rigid.

How Actuators Are Selected

Choosing the right actuator for a robotic application involves balancing several factors:

• Force and torque requirements: How much force or rotational torque must the actuator produce? This determines the size and type of actuator needed.
• Speed: How fast must the actuator move? High-speed applications favour electric motors, while high-force applications may require hydraulic systems.
• Precision: How accurately must the actuator position itself? Applications requiring sub-millimetre accuracy need servo motors with high-resolution encoders.
• Duty cycle: How often and for how long must the actuator operate? Continuous operation requires actuators with good thermal management to prevent overheating.
• Environment: Temperature, humidity, dust, and cleanliness requirements influence actuator selection. Pneumatic actuators suit clean environments, while sealed electric actuators handle harsh conditions.
• Size and weight: Space constraints and payload considerations limit actuator dimensions and weight. Collaborative robots, which must be lightweight, favour compact electric actuators.

Business Impact of Actuator Technology

Production Speed and Quality

Actuator performance directly determines how fast a robot can move and how precisely it can position itself. Higher-quality actuators enable faster cycle times and tighter manufacturing tolerances, both of which impact production throughput and product quality.

Energy Efficiency

Actuators are the primary energy consumers in robotic systems. Electric servo actuators typically operate at 80-90% efficiency, while hydraulic systems operate at 40-60%. In factories with many robots, actuator efficiency significantly affects energy costs.

Maintenance and Reliability

Actuator failures are among the most common causes of robot downtime. Electric brushless motors can operate for 20,000 or more hours between services, while pneumatic systems require regular maintenance of air quality components. Actuator reliability directly impacts production uptime.

System Cost

Actuators and their associated drives and controllers represent 30-50% of the total cost of a robotic system. The actuator selection significantly influences both the initial investment and long-term operating costs.

Actuators in Southeast Asian Robotics

The actuator market in Southeast Asia is growing alongside the region's expanding robotic installations:

• Electric motor dominance: The shift from pneumatic and hydraulic to electric actuators in manufacturing aligns with the region's focus on energy efficiency and clean production environments, particularly in electronics manufacturing across Malaysia, Vietnam, and Thailand.
• Local assembly: Some actuator manufacturers are establishing production in Southeast Asia, improving availability and reducing lead times for regional robot builders and integrators.
• Climate considerations: The hot, humid conditions in many Southeast Asian factories require actuators with appropriate thermal management and environmental sealing, making actuator specification particularly important in the region.
• Cost sensitivity: Southeast Asian manufacturers often seek the optimal balance between actuator capability and cost, driving demand for mid-range actuators that provide good performance without premium pricing.

Emerging Actuator Technologies

Direct Drive Actuators

Eliminate gearboxes by coupling motors directly to robot joints, reducing mechanical complexity, backlash, and maintenance requirements. Increasingly used in collaborative robots and high-precision applications.

Soft Actuators

Flexible actuators made from elastomers and other compliant materials that bend, stretch, and twist like biological muscles. They are enabling new categories of robots that can safely interact with humans and handle delicate objects.

Integrated Smart Actuators

Actuators with built-in sensors, controllers, and communication interfaces that operate as self-contained intelligent modules. They simplify robot design and enable distributed control architectures.

Considerations for Actuator Selection

1. Define your performance envelope: Specify the required force, speed, precision, and duty cycle for each axis of your robotic system
2. Consider total cost of ownership: A cheaper actuator that requires frequent maintenance or replacement may cost more over the robot's lifetime than a premium alternative
3. Evaluate environmental compatibility: Ensure actuators are rated for the temperature, humidity, and cleanliness conditions of your operating environment
4. Plan for spare parts availability: Select actuators from manufacturers with strong supply chains and service networks in your region
5. Test before committing: Request sample units for evaluation testing under your actual operating conditions