Soviet poster "Automatic production control system - national economy!", artist R. Suryaninov, 1972
"It would be great to see a story about modeling complex systems."
And I promised to pick up something from real life.
For modeling, use UML - Unified Modeling Language, unified modeling language .
Enterprise Architect from the Australian company Sparx Systems  is used as a modeling tool.
Modeling Methodology and Convention
Before designing, it is necessary to establish certain rules and approaches that we will follow when developing diagrams, the same rules will be used when “reading” diagrams. Details of the main approaches are described in [3, 4].
Stage 1. We develop a process map using the Use-case diagram, put all identified target processes on it - Use-case elements, and process participants - Actor elements, try to group the processes right away by meaning (if possible, of course).
Stage 2. Describe each process in the form of an Activity diagram. For a process in which more than 10 steps are highlighted, it makes sense to apply the principle of decomposition of the steps of the process in order to increase the readability of the diagram. For the lower level Activity diagrams, we apply the structuring of the diagram field using “swim lanes” - Swim lanes. The track name will correspond to the type of chart elements that will be placed on this track. "I/O. Objects ”: Objects elements will be located on this track - objects that are used or are the result of a certain process step. "Activity": here we put the elements of the Activity - the actions of participants in the process. “Role”: the track for the elements that will represent the roles of the performers of actions in our process, for them we will use the same modeling element Object - the object, but we will add the stereotype “Actor” to it. The next track is called “Rules” and on this track we place in the text form the rules for executing the steps of the process, and we will use the modeling element Note for this. The path "Tools" will be used to collect information about the level of automation of the process.
Stage 3. Select what can be automated. We will have three types of steps: manual, automated, and fully automatic.
Step 4. The automated step needs to be associated with a function or system functions (the relationship may be many-to-many), draw a Use-case diagram. These are the functions of our system.
Step 5. We describe the internal organization of the system using the class diagram - Class. Swimming track "I/O. Objects ”in the Activity diagram is the basis for constructing an object model and an entity-relationship model.
Stage 6. Let's analyze the notes on the “Rules” track, they give various kinds of restrictions and conditions, which are gradually transformed into non-functional requirements.
Step 7. The elements on the Tools track tell us about the level of process automation.
The resulting set of diagrams gives a formalized description in a fairly strict notation, i.e. has an unequivocal reading. Now you can develop a technical task, specify the specification of requirements, etc.
Modeling elements of the Use-case diagram for the process map
Modeling Activity Chart Elements
The automation object is quality assurance processes for the production of medical devices.
The process of manufacturing medical devices is characterized by a large number of manual operations. Quality management is regulated in accordance with GOST ISO 13485-2011. Medical products. Quality management systems. System requirements for regulatory purposes.
To carry out quality control, it is necessary to monitor and record all operations in the manufacture of a medical product for subsequent investigation of possible incidents.
Barcode is used as the registration information carrier. For reading information using a remote barcode reader.
The developed automated system (AS) for controlling the manufacture of medical devices is designed for:
Figure 1 shows a map of the AU processes for controlling the manufacture of medical devices. Processes for which the following scenarios will be shown below are highlighted in green.
Figure 1. Map of the processes of the automated control system for manufacturing medical devices
Figures 2-5 show examples of scenarios for the execution of AU processes for controlling the manufacture of medical devices.
Figure 2. Preparation for work (start of shift)
Figure 3. Manufacturing honey. products (macro steps)
Figure 4. Start of manufacturing medical products
Figure 5. Manufacturing medical products
In the Activity diagrams, states are indicated in square brackets before or after the object names.
The full life cycle of a medical device is shown in the State Chart (Figure 6).
Figure 6.Production Health State Diagram
The system is logically divided into subsystems according to the functional attribute:
Automated processes in terms of subsystems and modules are presented in the figure below (Figure 7).
Figure 7. Automating processes in terms of subsystems and modules
This is, of course, not all diagrams, but I think that it’s enough to give an idea of the model.
When we started to develop the system, the knowledge of the subject area was based only on the half-page about medical devices mentioned at the beginning of GOST ISO 13485-2011. The models were discussed with the customer, there were no particular difficulties in “reading” the models.