Understanding Actuators for IoT

Actuators are the workhorses of the Internet of Things and enable the automation or remote control of a wide range of processes in sectors that include consumer, industrial, healthcare, and transportation. This short article explains the role of actuators in IoT and outlines the different types of actuators that are used.

What is an actuator?

Actuators are simply devices that convert energy into action or motion. Though their invention and use predate IoT, they have become essential hardware components for practical IoT applications. IoT or smart products that use actuators differ from the applications that solely rely on sensors for monitoring‌.

Actuator hardware is diverse, with a variety of mechanisms, power sources, and long-term maintenance needs. For IoT products to be effective and function properly, the right actuator has to be selected. Actuators also have to integrate into product workflow so that they enable its physical action based on sensor-based data.  

How do IoT actuators work?

In IoT circuits or systems, actuators are used to produce a physical action or movement in response to data from sensors in the circuit. Here are the steps by which sensor data is converted to actuator movement: 

• IoT sensors monitor specific environmental factors like temperature or humidity. They are programmed with a threshold that triggers a data transmission if it is exceeded. 
• If there is an event that exceeds the threshold setting of the sensor, it automatically transmits a data signal that conveys information about the event.
• The sensor wirelessly transfers the data to a control system or software application that can determine what response is necessary.
• The controller then sends a signal a tells the actuator in the system to make its characteristic movement. This signal can be transferred via a wired, or wireless connection. 
• The actuator completes the action by turning energy (from the incoming signal or DC supply) into physical force.

 

4 key types of actuators

Electronics engineers classify actuators according to the energy source they use to operate:

[A] Electric actuators

These are the most common type of actuators. They convert electricity into mechanical movement. They function quietly but can achieve a high level of precision in their movements they are highly programmable. Electrical actuators may not ‌withstand the harshest operating environments.

[B] Hydraulic actuators

These industrial actuators are rugged and can exert a large amount of force at high speed. They are present in construction, manufacturing, agricultural and mining heavy machinery, using the movement of fluids under pressure to achieve movements. Though they are powerful, they often leak or bust and require a lot of maintenance. These components often require telemetry so that equipment failure can be remedied quickly. 

[C] Pneumatic actuators

These powerful actuators use the movement of compressed air to execute their action. They are durable and will withstand harsh conditions. They also can quickly activate and deactivate but should be monitored to ensure that their air pressure is maintained.

[D] Thermal/magnetic

These actuators are made of a metal that is a shape memory alloy, which changes shape when heating up or cooling down. The change in conformation of the metal produces the required movement. These actuators are lightweight with a high power density. A limitation of this type of actuator is that they take time to achieve the conformational change that produces the action. In time the metal becomes fatigued and will need to be replaced, adding to costs.

Actuators can also be classified according to the type of movement they produce. Select them according to the work you want them to do. The main motions are: 

[E] Rotary

These are cylindrical actuators that complete angular, rotary, or torque movement. They can use electrical, pneumatic, or hydraulic energy to achieve their mechanical rotation.

[F] Linear

The motion produced by a linear actuator is a straight movement in the horizontal or vertical plane. These are often pneumatic devices. 

[G] Oscillating 

These actuators produce a forward and backward rotary or angular movement at a specific frequency. 

Examples of IoT actuator applications  

1. A refrigerator unit that has a thermostat may use temperature sensors to monitor the temperature. If the temperature exceeds the thermostat threshold, the sensor automatically sends data to a controller that instructs an actuator to activate the refrigeration.
2. In a smart home, strategically positioned light sensors monitor daylight levels on the property. As the evening unfolds, the sensor sends data about light levels to the smart home controller that signals an actuator that causes window shades to fall and the lights to come on automatically when it becomes dark. 
3. On farms, humidity sensors that monitor soil moisture can send data to a controller if the soil becomes too dry. The controller can then signal an actuator that switches on irrigation to water the crops. 

Wireless networking is essential for actuator connectivity

IoT deployments often cover large geographical areas that separate the sensor, controller, and actuator. A wired connection cannot support these distinct and distant components. They usually rely on wireless and an internet protocol. Cellular networks, Wi-Fi, and LoRa can transfer data to cloud-based controllers and software applications for secure, reliable automation. 

Other actuator arrangements in IoT devices

Actuators may also be near the sensor and controller. An example of this is a smart valve that contains all three components. The actuator itself may require telemetry to monitor its function with sensors specifically assigned to its operation (opening and closing of valves, or temperature changes the actuator effects) rather than having it inspected by personnel. Here, actuator failure would trigger an alert so it can be repaired promptly.

Selecting IoT actuators

Actuators are chosen for applications to perform specific types of work. Developers work with automation hardware vendors to select actuators that will suit their applications. IoT applications usually use electric actuators. They are often sold as a package with sensors and other device components that are suitable for the use case.

As you can see, the use cases of actuators in Internet of Things technology are extensive and varied. Hopefully you now have a better understanding of the mechanics end of IoT, but should you have further questions or are in need of technical consultation, do not hesitate to reach out to the experts at Envative.