When working in tandem within a given system, actuators receive signals from sensors and perform some kind of task based on that input. To understand how that works, we’ll have to look at how both sensors and actuators function.
The role of sensors
Sensors monitor environmental conditions, such as the level of fluid in a tank, the vibrations of a ball bearing system, or the temperature of a furnace. The input from the environment is converted to an electrical signal which can be interpreted by other pieces of equipment.
For instance, a gas furnace will have a thermocouple that monitors the heat from the pilot light. As long as the pilot light keeps burning, the thermocouple generates a current. The greater the heat, the higher the voltage will be.
The role of actuators
Fundamentally, an actuator is a device that causes movement. It takes input—often an electrical signal—and energy, which it then converts into physical motion. An actuator may be pneumatic, hydraulic, electric, thermal, or magnetic.
For example, a hydraulic cylinder on an excavator uses pressure from hydraulic fluid to push and pull on the piston rod within the cylinder barrel. That lateral movement is used to move the arm on the excavator.
Actuators and sensors together
Going back to our furnace example, we can see how sensors and actuators often work together.
In furnaces, the gas shutoff valve is connected to the thermocouple. As long as the pilot light is going, the thermocouple generates a current, and that current keeps the valve open. As soon as the current stops—such as if the pilot light goes out—the valve shuts, preventing gas from accumulating in the furnace and reducing the risk of an explosion.
In this case, the sensor (the thermocouple) provides both the energy and the signal for the actuator (the shutoff valve). In other systems, the setup may be more complex with multiple sensors and actuators working in tandem to perform a given task. However, the basic principle remains—the sensor provides a signal, and the actuator adjusts based on that signal.
Likewise, the movement from an actuator may register on a sensor, allowing it to control other components of a system accordingly or provide performance data for condition-based maintenance.
In the last post, we saw how sensors play a very important role in the Internet of Things ecosystem. Sensors are used for collecting data. The next logical question that arises is “What can be done with this data?”
Data can be processed, analyzed, reported or can be used to trigger another event. In this article, we would be more interested in the scenario of an action or data pattern that triggers another event.
Consider a situation where you would like your water pump to be switched on when the water level in the tank goes below a certain level. How would you design this system? You would have a sensor to measure the level of water. You will configure this system in such a way that once the sensor learns that the water has gone down a particular level, it will send an alert to the controller (this would be an embedded system assembly). The controller in turn would trigger an actuator to switch on the water pump.
What is the role of an actuator here? It simply triggers a mechanical action when it is supplied with energy (through the form of electricity, air or water). As an analogy, you could consider the turbines being set in rotatory motion when water flows over it at high speeds.
An actuator is a device that converts energy into motion. It is usually used to apply a force on some thing. In our example, the actuator would apply force to switch on the motor of the water pump. Actuators can create linear, oscillatory or rotatory motion based on how they are designed.
In the scheme of Internet of Things, actuators are used whenever there is a need to switch on/off another device or equipment by applying a force. You should remember that IOT is not just about reading and processing of data, but triggering various devices into operation based on the dynamics of the data. Most of the automation in IOT happens through the combined use of sensors and actuators. Thus, they form the back bone of IOT.
There is no limit on what can be achieved through IOT. This technology is there to improve the quality of our lives. I encourage you to think of real life scenarios where the combination of sensors and actuators be used to solve a problem that we face frequently. After all, technology should be used for problem solving, isn’t it?
The Internet of Things is taking the world by storm – but what is it exactly? In this blog article, we explain the Internet of Things in depth, explore the numerous devices, architectures, and applications in this exciting emerging area.
The Internet of things is defined as a paradigm in which objects equipped with sensors, actuators, and processors communicate with each other to serve a meaningful purpose. IoT could also be looked at as simply an interaction between the physical and digital world. Once stand-alone devices and applications now have the potential to be connected to a network through sensors, actuators, processors, and transceivers.
Actuators and sensors are devices that enable interaction with the physical world.
For example, Moti is an actuator. Moti creates smart motors and apps for robots. Attach the smart motor to anything, add power, and Moti gives you the ability to control the item from your desktop browser. Actuators are devices that are used to manipulate the physical environment, such as the temperature control valves used in smart homes. Actuators take electrical input and transforms the input into tangible action. These technologies collect a high amount of data, which can be very valuable and useful to an enterprise once it has been stored, organized, and processed.
Simply put, IoT isn’t just one technology – but a combination of various deeply connected technologies.
Source: Bridgera
Many challenges come with the data collection, handling, communication, and processing of the data. These IoT devices collect a high amount of information, and it is up to the end user to decide which data is relevant for their situation, which places to process or store it, and the desired communication level. Storage, pre-processing, and processing of data can be done on a remote server or on the edge of the network itself.
Sensors, actuators, compute servers, and the communication network forms the core infrastructure of an IoT Framework. At times, other pieces of technology are needed such as middleware. Middleware is software that acts as a bridge between an operating system or database and applications, especially on a network. Middleware can be used to connect and manage all autonomous IoT components.
The Three-Layer Architecture of an IoT-System
Layer one consists of wireless sensors and actuators. Layer two includes the addition of sensor data aggregation systems and analog-to-digital data conversion. In layer 3, the data is fed to or used to improve an application.
Layer 1: Physical
Sensors collect data from the environment or object under measurement and turn it into useful data. This stage of the IoT is expanding rapidly, with robotic camera systems, water level detectors, home voice controllers, air quality sensor, smart baby monitoring devices, etc.
All of these devices will collect user data, including sign-on times, level and hours of usage, location statistics, etc. As these devices produce an avalanche of data, it will be important to your organization to choose which data is useful to you and which can be ignored. Enterprises can expect a surge in data velocity, and with that surge, organizations will benefit from moving their data into the cloud. Some data should be processed immediately, i.e., time-sensitive data – threat detection, immediate crash statistics, abrupt shutdowns, etc. Otherwise, data that will undergo deep processing and analyzation should be pushed directly to the cloud, to avoid network clutter.
Layer 2: Network
Data collected from the sensors or actuators is very raw. This data has to be aggregated and converted into digital streams for further data processing. To carry out this data processing, it is imperative to use a data acquisition system (DAS or DAQ). Data acquisition is the process of sampling signals that measure real world physical conditions and converting the resulting samples into digital numeric values that can be manipulated by a computer. Data acquisition systems typically convert analog waveforms into digital values for processing.
The DAS connects to the sensor network, aggregates outputs, and performs the analog-to-digital conversion. The Internet gateway receives the aggregated and digitized data and routes it over Wi-Fi, wired LANs, or the Internet, to Stage 3 systems for further processing.
Layer 3: Application
This layer is responsible for delivering application specific services to the user. Once data has been aggregated, cleaned, and surveyed, the information can be fed to the server to be analyzed and applied to new products and services.