CPS are a network of many different technologies that serve to connect the real world with the virtual world. In more professional technical terms, this refers to a network of mechanical systems that are controlled and monitored by a computer-based process.
The various technologies are used to perceive measure and name context-dependent processes – and to derive and implement the appropriate approach from these. This is done across machines via a network.
Of course, the right technology has to be found – the good thing is that it has already been invented and is in use! CPS are the backbone of Industry 4.0, especially because their developments made a networked production environment theoretically conceivable in the first place.
Now things are getting a little complicated: The technologies in use actually form systems themselves. The “embedded systems” discussed above as part of CPS, for example, are not called this way for no reason – CPS can therefore be seen more as a kind of a “super-system” of smaller subsystems.
The following example should explain this better:
A system of systems
An office building has installed a separate system for fire protection in each of its rooms. Each of these systems consists of a sensor that detects an outbreak of fire, an alarm that sounds in case of fire and a fire extinguishing system on the ceiling.
Suppose the dust bin starts to burn in room A – the sensor detects this, the alarm sounds and the fire extinguishing system starts to spray water. Room B on the next floor, however, does not yet notice this.
But if the systems in room A and room B are now connected to each other, sensor A can report to sensor B: “We’re on fire!” Sensor B can now promptly decide to trigger the alarm so that this room is also evacuated, but not to activate the fire extinguishing system – because there is no fire in room B (yet).
Thus, a context-dependent decision was automated across the system and executed in real time.
The required technologies can be divided into three core technologies:
The following diagram shows how these are connected:
Of course, such a model is of very little use if you do not understand the individual components:
Physical elements – between control and processing
These are essentially the embedded systems, i.e. subsystems, mentioned above. These consist of:
- Actuators: These are mostly components of drive technology – this does not necessarily mean that something is moving, but that at least something is being moved. For example, a robot arm that turns a component over needs a motor to move it. It is essential that such an actuator can be controlled by an electrical signal.
- Sensors: These are the counterparts of the actuators – they “sense” their environment according to physical or chemical properties (e.g. pressure, heat, brightness, etc.) and represent these by means of a measured variable (e.g.: temperature of the work piece = 10 degrees Celsius). This measured variable can be further processed as an electrical signal.
- Microcontroller: The brain of an embedded system – also called a “chip” – the microcontroller performs computing tasks like a computer. It monitors, controls and transfers processes automatically, depending on its programming.
Behold: actually, the combination of physical elements is nothing more than a robot! It senses its environment with its sensors, moves and acts accordingly with its actuators, and it acts exactly as dictated by its microcontroller. It is important that it can react dynamically to its environment and that actions and measurements can be carried out simultaneously.
Cyber elements – between control and communication
The cyber elements serve the virtual world of data transfer and data processing. Here, data becomes information and information becomes knowledge. One thing above all is needed for this
– a proper network technology!
- Internet: With such amounts of data in real time, a super-fast broadband Internet must be available. But new mobile phone standards such as 5G can also help with data transfer.
- Address space: Each element also needs its own Internet address. New, more comprehensive Internet protocols such as IPv6, which allow many more different Internet addresses, can ensure that each element has its own unique, unambiguous address.
- Cloud-Computing: In order to process the amounts of data quickly, you need a lot of computer power – you can access external servers, which take over computing power and provide additional storage space for databases.
Data must arrive, be calculated and put into context in real time. Based on this knowledge, a decision must now be made on how to proceed in the production environment (remember the fire alarm example) and this must be forwarded to the appropriate subsystems. These then implement – and then everything starts all over again.
Systemic elements – between communication and processing
After all, this is about the connection and application of a large system – that is rather theoretical. In this re
spect the discipline of so-called “systems engineering” is helpful. This is where the demands on the CPS are defined and appropriate measures are taken:
- Request: What is to be done anyway? Which machines have to be set up in relation to each other so that they can work together (e.g. in a production line).
- System integration: Which interfaces do the individual systems need to be integrated into the larger one? Which software is used?
- Quality assurance: How are errors analysed? How are they repaired? What is the fault tolerance of a single subsystem compared to the whole system?
CPS generate data, information and knowledge from physical processes. These are processed in real time, dynamically control processes and are connected via a network.
This requires three core technologies: Control, Computation and Communication.
These are fulfilled by the following technological modules and concepts:
CPS are nothing more than super systems of different subsystems with these technological building blocks