Architecture of Cyber-Physical System

Quiz

Cyber-Physical System (CPS) combine physical and computational environments. It is used to monitor and control data in real-time. There is a layered architecture of CPS just like the OSI model in Computer networks. But instead of 7 layers, CPS has only three layers: Perception layer, Transport layer, and Application layer.

Each of these layers have their own functionalities and components. In this chapter, we will discuss the various components and layers of CPS architecture, including the following −;

Perception Layer
Transport Layer
Application Layer
CPS Devices (Sensors and Actuators)
Communication Interfaces
Control Systems
Data Processing and Storage
Feedback Loops
Security Systems

Let us now discuss each of these in detail.

Perception Layer

It is the first layer in CPS architecture. There are devices like sensors in this layer. These devices collect real-time data from various sources. There are various devices like sensors, RFID tags, cameras, GPS, lasers, etc. We use these devices to detect and monitor physical conditions like temperature, location, pressure, etc. These can also convert digital signals into data to process to the system.

The functionalities of the Perception Layer include the following −

Detect changes in real-time
Collect and transmit data for analysis
Convert physical signals into signals

Transport Layer

The transport layer is the second layer in the CPS architecture. We use this layer to communicate between the Perception Layer and the Application Layer. Transport layers transfer the data. We collect this data from devices like sensors and transfer it to the Application Layer. We process and analyze this data in the Application layer.

We use communication tools to transfer the data. Examples of these tools include: Ethernet, Wi-Fi, Bluetooth, Zigbee, 4G/5G, Internet protocols, etc.

The functionalities of the Transport Layer are given below −

It communicates between layers
Manage network protocols and data routing in this layer
Data reaches its destination accurately and securely in this layer

The work of this layer is the same as the transport layer of the OSI model of the computer network.

Application Layer

This is the final layer of the CPS architecture. We take decisions at this layer. We process and analyze data in this layer. We take data from the Transport Layer using intelligent algorithms and software. Application Layer sends commands to physical devices based on this analysis. We control the system in real-time in this layer.

Some of functionalities of the Application Layer are given below −

Process and analyze data in this layer
Send control signals to physical devices from the layer
Optimize the performance of the system

This layer works the same as the application layer of the OSI model of the computer network.

CPS Devices (Sensors and Actuators)

We use various types of digital devices like sensors and actuators. We use these devices as the physical components that interact with the environment. These devices are required for the functioning of CPS. These are explained as below in brief −

Sensors − Sensors are located in the Perception Layer. Sensors detect environmental changes like temperature, light, and movement. We collect data and send it to the Transport Layer for processing using sensors.
Actuators − These receive commands from the Application Layer. Actuators perform physical actions like adjusting a valve, starting a motor, and controlling machinery. Actuators translate digital instructions into physical movements. So CPS can interact with its environment as needed.

These devices are the building blocks of CPS. These are like the hardware components in a computer network.

Communication Interfaces

We use communication Interfaces to flow data between the various CPS layers and components. These interfaces support standardized communication protocols like MQTT, CoAP, and HTTP. You can use these between devices from different manufacturers.

The functions of Communication Interfaces include the following −

Transfer data between CPS layers and devices
Secure channels for data transmission

These interfaces function like open interfaces in a software-defined network (SDN).

Control Systems

Control Systems are the central management units of CPS architecture. It includes systems like Programmable Logic Controllers (PLCs), Distributed Control Systems (DCS), and Supervisory Control and Data Acquisition (SCADA). We monitor real-time data from sensors and send instructions to actuators based on the data analysis using these systems.

The functionalities of Control Systems include the following −

Manage physical processes based on data-driven analysis
Ensure the system operates efficiently

Control Systems in CPS work the same as the central processing unit (CPU) in an operating system. It coordinates control of the entire system.

Data Processing and Storage

Storing and processing data play an important role in the CPS architecture. We get the data from the sensors. This data is used for various insights. Storage systems get this data for historical analysis and future decision-making.

The functions of this component are given below −

Analyze real-time data for immediate action
Store the data for future reference and learning
Support intelligent algorithms for decision-making

This component is just the same as memory management in an operating system.

Feedback Loops

We create a continuous cycle of data collection using feedback loops. Sensors collect data, the system processes it, and then the actuators respond. The results are monitored again, so it forms a dynamic loop that allows the system to adjust to real-time changes.

The functions of Feedback Loops include the following −

Monitor and control real-time data
Adjust the system based on environmental changes
Ensures optimal performance through continuous updates

These loops are the same as the interrupt handling mechanisms in an operating system.

Security Systems

Security is an important component of CPS architecture. We interact with physical environments and networks. So we require strong security measures, like encryption protocols, firewalls, and intrusion detection systems. We protect the system from cyber threats and unauthorized access.

The functions of Security Systems include the following −

Protect data during transmission and storage
Monitor and detect cyber threats
Ensures the safe operation of physical devices and network components

These security measures are the same as the security management systems in an operating system.

Conclusion

Cyber-Physical System are used for real-time monitoring and control. CPS distributes its functions across different layers for communication, efficient data processing, and precise control over physical processes.

CPS combines sensors, actuators, control systems, and communication interfaces. CPS bridges the gap between physical processes and digital intelligence. CPS is just like computer networks, where protocols and components must interact with each other to ensure smooth functioning.

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