MBSE-based system modeling and evaluation method

Abstract

The invention discloses a system modeling and evaluation method based on MBSE. The method comprises the steps of rocket system demand analysis and modeling; performing rocket system function analysis and modeling; designing and modeling a rocket system architecture; evaluating a rocket system design scheme. The SysML language adopted by the method is a modeling language oriented to system engineering, a unified data source is formed for complex systems involving multiple disciplines such as machinery, electronics, control, hydraulic pressure and the like, and semantic consistency is guaranteed. The system modeling and evaluation method based on the MBSE is adopted, the SysML can establish the incidence relation between the elements, and establishment of a tracing mechanism is facilitated. According to the method, the SysML is converted into the Python codes, multi-criterion comprehensive trade-off evaluation is carried out on the multiple design schemes by utilizing the analysis capability of the Python scripts, the multi-criterion comprehensive trade-off evaluation can be carried out on the multiple design schemes, and the system development efficiency is improved.

Description

Technical Field

[0001] The present invention relates to the technical field of system modeling and simulation, and in particular to a system modeling and evaluation method based on MBSE. Background Art

[0002] The rocket system is a vehicle that is propelled forward by the reaction force generated by the working fluid (working medium) ejected by the rocket engine. It is a vehicle for space flight. As a complex mechanical system, the overall design process of the rocket system has the characteristics of complex system engineering, such as many iterative modifications, high technical difficulty, and numerous coordination units. The system engineering method needs to be used in its design process. The top-level design of the rocket system involves multiple disciplines such as control, structure, and control. In the traditional development process, a document-based system engineering development model is adopted. The design plan exists in the form of a huge number of documents. It is difficult to ensure the consistency and traceability between various design documents in the iterative design process.

[0003] With the rapid development of technologies such as digital twins, cloud computing, artificial intelligence, and big data, the level of digital design has been improved, and model-based systems engineering (MBSE) has gradually replaced document-based systems engineering. MBSE uses SysML as the standard modeling language and performs system forward design based on SysML. It can describe the system design in a standardized and unified manner, forming a traceable system design model. The model is used throughout the entire life cycle of system development, which can effectively ensure the consistency and traceability of the design scheme. However, SysML can only perform simple numerical calculations on the design scheme through parameter diagrams, and cannot perform multi-criteria comprehensive trade-off evaluation on multiple design schemes. Summary of the invention

[0004] The present invention provides a system modeling and evaluation method based on MBSE, which solves the problem that text-based system engineering is difficult to ensure consistency and traceability in design solutions and SysML is difficult to perform multi-criteria comprehensive trade-off evaluation of design solutions, thereby improving system development efficiency.

[0005] In the first aspect, a system modeling and evaluation method based on MBSE is provided, including:

[0006] Perform requirements analysis on the rocket system and create SysML requirements diagram in MBSE based on the requirements analysis results;

[0007] Create a use case for the rocket system and decompose it into sub-use cases. Create associations between the requirements analysis results, sub-use cases, and external objects that interact with the rocket system. The external objects are used to trigger the sub-use cases. The requirements corresponding to the sub-use cases are indicated by the requirement-use case association relationship.

[0008] Perform functional analysis on the rocket system to obtain the functional activity diagram, further decompose and merge the functional activity diagram in MBSE, and assign the functional activities to specific structures to form the rocket system structure composition result;

[0009] According to the rocket system structure composition results, the architecture design is performed in MBSE, including determining the system composition results included in the rocket system architecture, and establishing associations between the various systems included in the rocket system architecture, on this basis forming multiple rocket system architecture design schemes;

[0010] Multiple rocket system architecture design schemes are output from MBSE and converted into Python codes to evaluate them.

[0011] In conjunction with the first aspect, in certain implementations of the first aspect, performing demand analysis on the rocket system includes:

[0012] Sort out the rocket system development requirement items and divide the requirements into functional requirements and non-functional requirements; the functional requirements include at least: propulsion requirements, transportation requirements, control requirements and safety requirements; the non-functional requirements include at least: interface requirements, economic requirements and weight requirements; enter the requirement items stored in the document into the requirement table, the table header contains name and comments, which include the requirement number, name and comments respectively.

[0013] In conjunction with the first aspect, in certain implementations of the first aspect, establishing a SysML requirement diagram in MBSE according to the requirement analysis result includes:

[0014] Create a SysML requirement diagram based on the requirement items. Id represents the number of the requirement, and Text represents the description of the requirement, that is, the comments in the requirement table.

[0015] In combination with the first aspect, in some implementation methods of the first aspect, the rocket system includes two use cases: launch and flight. The launch use case includes two sub-use cases: ignition and transportation. The flight use case includes two sub-use cases: navigation and payload release. The external objects that interact with the rocket system include operators and payloads. The association tool is used to associate the operator with the ignition use case, and the payload with the transportation and payload release use cases, to clarify that the use case scenario is triggered by the operator and payload. The propulsion and transportation requirements are associated with the launch and transportation use cases, and an association relationship between requirements and use cases is established.

[0016] In conjunction with the first aspect, in certain implementations of the first aspect, performing functional analysis on the rocket system includes:

[0017] For the rocket system use case, use activity diagrams to analyze the behavior principles of the rocket system to achieve its functions and construct a functional activity diagram for the rocket system, including launch, flight, and fall;

[0018] The functional activity diagram is further refined and decomposed. By subdividing the functional activities at different levels, the system functional activities are decomposed step by step. The launch functional activities are refined into: loading payload, providing thrust, and safety control; the flight functional activities are refined into: providing thrust, guidance, controlling attitude, telemetry data, external measurement data, and safety control;

[0019] Combine the thrust providing and safety control functions of both launch and flight activities;

[0020] According to the current technical conditions, functional activities are assigned to specific structures. The load-carrying function is assigned to the rocket body structure; the thrust-providing function is assigned to the power system; the guidance and attitude control function is assigned to the control system; the telemetry data function is assigned to the telemetry system; the external measurement data function is assigned to the external measurement system; and the safety control function is assigned to the safety system.

[0021] The structural composition of the rocket system is determined according to the functional allocation, including the rocket body structure, power system, control system, telemetry system, external measurement system and safety system.

[0022] In conjunction with the first aspect, in certain implementations of the first aspect, performing architecture design in MBSE according to the rocket system structure composition result includes:

[0023] According to the functional analysis results and combined with the current technical conditions, the rocket system structure is obtained and the rocket system architecture is defined using the module definition diagram, and its weight and cost design parameters are defined;

[0024] Use internal module diagrams to define interfaces and interactions between structures, where the rocket body system is connected to the external measurement system, telemetry system, and safety system, respectively; the telemetry system and external measurement system are both connected to the power system; and the control system is connected to the safety system and power system;

[0025] Based on the rocket system architecture and combined with existing examples, six modules including rocket body structure, power system, control system, telemetry system, telemetry system and safety system are designed, and multiple rocket system design schemes are obtained and expressed using example elements.

[0026] In combination with the first aspect, in certain implementations of the first aspect, the step of outputting multiple rocket system architecture design schemes from MBSE and converting them into Python codes to evaluate the multiple rocket system architecture design schemes includes:

[0027] Based on the mapping relationship between SysML2.0 and Python, determine the conversion relationship between rocket system design scheme and Python code;

[0028] Select the solution to be evaluated and generate the Python evaluation code for the solution to be evaluated;

[0029] A multi-criteria comprehensive trade-off evaluation is performed based on the various evaluation indicators of the design scheme, and the numpy library is called to display the results as radar charts and bar charts.

[0030] In conjunction with the first aspect, in some implementations of the first aspect, the Python evaluation code includes:

[0031] The first part is the class declaration code: use the Python keyword class to declare the system, and define the value and composition of the class according to the system composition;

[0032] The second part is the instantiation code: instantiate the above class and assign initial values ​​according to the default values ​​of the SysML model;

[0033] The third part is the evaluation code: write the evaluation analysis code according to business needs, directly edit the Python script in the script editing window or import the edited Python script.

[0034] In combination with the first aspect, in certain implementations of the first aspect, the radar chart is used to compare and evaluate the cost, quality, flight speed, and thrust, and the bar chart is used to evaluate the cost performance.

[0035] In a second aspect, a computer program product is provided. When the computer program product is executed by a processor, the steps of the MBSE-based system modeling and evaluation method as described in any one of the implementations of the first aspect are implemented.

[0036] Compared with the prior art, the solution provided by the present invention includes at least the following beneficial technical effects:

[0037] 1. The SysML language used in the present invention is a modeling language for system engineering. It provides a unified modeling method for complex systems involving multiple disciplines such as mechanics, electronics, control, and hydraulics, forms a unified data source, and ensures semantic consistency.

[0038] 2. The present invention adopts a system modeling and evaluation method based on MBSE. Compared with the existing text-based system engineering method, SysML can establish the relationship between elements, which is conducive to establishing a traceability mechanism.

[0039] 3. The present invention converts SysML into Python code and uses the analysis capability of Python script to perform multi-criteria comprehensive trade-off evaluation on multiple design schemes. Compared with SysML parameter diagrams that can only perform simple numerical calculations on design schemes, this invention can realize multi-criteria comprehensive trade-off evaluation on multiple design schemes and improve system development efficiency. BRIEF DESCRIPTION OF THE DRAWINGS

[0040] Figure 1 This is a flow chart of the system modeling and evaluation method based on MBSE.

[0041] Figure 2 Schematic diagram of the results of the MBSE-based system modeling and evaluation method. DETAILED DESCRIPTION

[0042] The present invention is further described in detail below with reference to the accompanying drawings and specific embodiments.

[0043] The present invention provides a system modeling and evaluation method based on MBSE, and the specific steps are as follows.

[0044] Step 1: Perform requirements analysis on the rocket system and create a SysML requirements diagram in MBSE based on the requirements analysis results. The requirements analysis phase outputs the rocket system development requirements and requirements indicators.

[0045] First, sort out the rocket system development requirements and divide them into functional requirements and non-functional requirements. Functional requirements include at least: propulsion requirements, transportation requirements, control requirements and safety requirements; non-functional requirements include at least: interface requirements, economic requirements and weight requirements. Enter the requirements stored in the document into the requirements table. The table header contains name and comments, which include the requirement number, name and comments respectively.

[0046] For example, the requirements of the rocket system, numbered 1, include functional requirements (numbered 1.1) and non-functional requirements (numbered 1.2). Functional requirements include propulsion requirements (numbered 1.1.1, annotated as propulsion itself into the atmosphere), carrying requirements (numbered 1.1.2, annotated as propulsion capacity N tons), safety requirements (numbered 1.1.3, annotated as control to terminate the rocket's powered flight and blow it up when a failure threatens ground safety), and control requirements (numbered 1.1.4, annotated as guidance and attitude control). Taking safety requirements as an example, safety requirements can further include safety monitoring (numbered 1.1.3.1, annotated as monitoring the status of the rocket and judging whether it is safe), stopping power (numbered 1.1.3.2, annotated as stopping power in time when encountering a failure or danger), and self-destruction (numbered 1.1.3.3, annotated as self-destruction when it is judged to be safe). Non-functional requirements include interface requirements (numbered 1.2.1, annotated as supporting telemetry and remote control with the ground), economic requirements (numbered 1.2.2, construction costs not exceeding X yuan), and weight requirements (numbered 1.2.3, annotated as weight not exceeding Y tons).

[0047] A SysML requirement diagram is created based on the above requirement items. The requirement diagram is not only the result of graphical modeling of itemized requirements, but also manages the requirements by using associations such as traceability and composition, so as to obtain the logical relationship between the requirements intuitively and clearly. Id represents the number of the requirement, and Text represents the description of the requirement, i.e., the comments in the requirement table. The top level is "rocket system requirements", which includes two sub-requirements: "functional requirements" and "non-functional requirements", which can be further decomposed. For example, functional requirements also include "transportation", "safety", "control" and other requirements.

[0048] Step 2: Establish a use case for the rocket system and decompose it into sub-use cases, and establish associations between the requirements analysis results, sub-use cases, and external objects that interact with the rocket system. The external object is used to trigger the sub-use case, and the requirements corresponding to the sub-use case are indicated by the requirement-use case association relationship.

[0049] The functional requirements of the rocket system are decomposed and refined by establishing use cases and decomposing them into sub-use cases. The system is observed as a black box from the top-level perspective, and the functional scenarios (i.e., use cases) that the system should provide are considered. The rocket system contains two use cases, "launch" and "flight". The "launch" use case contains two sub-use cases, "ignition" and "transportation", and the "flight" use case also contains two sub-use cases, "navigation" and "load release". The external objects that interact with the rocket system are mainly operators and loads. Using the association tool, the operator is associated with the "ignition" use case, and the load is associated with the "transportation" and "load release" use cases, which clarifies that the use case scenario is triggered by the operator and the load. The "propulsion" and "transportation" requirements are associated with the "launch" and "transportation" use cases, and the relationship between requirements and use cases is established. The requirements analysis phase mainly outputs the system development requirements, requirement indicators, and the functional scenarios (use cases) that the system should provide as input for subsequent stages.

[0050] The requirements analysis results, sub-use cases, and the relationships between external objects that interact with the rocket system can form a functional scenario for the rocket system, which can then serve as input for functional analysis in subsequent steps.

[0051] Step 3: Perform functional analysis on the rocket system to obtain the functional activity diagram. In MBSE, the functional activity diagram is further decomposed and merged, and the functional activities are assigned to specific structures to form the rocket system structure composition result.

[0052] The functional analysis phase uses the functional scenario as input, analyzes the functional behavior principle of the rocket system to realize the functional scenario, obtains the rocket system functions and functional indicators and allocates them to specific structures. Through steps 1 and 2, the rocket system use case (functional scenario) is constructed, and the system is observed from the top-level black box perspective, which explains the functions provided by the system. The functions require specific functional carriers, i.e. structures, to be implemented. In this functional analysis phase, the system functions are analyzed more deeply from a white box perspective to identify the structural composition of the rocket system.

[0053] For the rocket system use case, the activity diagram is used to analyze the behavior principle of the rocket system to achieve its functions, thereby constructing the functional activity diagram of the rocket system, including launch, flight, and fall. The functional activity diagram can be used to illustrate the functional behavior of the rocket, that is, when the rocket is successfully launched, it will fly stably and finally fall.

[0054] The functional activity diagram can be further refined and decomposed, and the step-by-step decomposition of the system's functional activities can be achieved by subdividing the functional activities at different levels.

[0055] The "launch" function can be broken down into: loading the payload, providing thrust, and safe control. In other words, first load the payload, then provide thrust, and finally control the rocket safely.

[0056] The "flight" function can be broken down into: providing thrust, guidance, attitude control, telemetry data, external measurement data, and safety control. In other words, first provide thrust and guidance, continuously adjust the attitude during flight, and perform safety control based on telemetry data and external measurement data to ensure the safety of the entire flight process.

[0057] In order to obtain a concise activity diagram that describes the overall behavioral activities of the rocket system, the "provide thrust" function and "safety control" function that are common to the "launch" activity and the "flight activity" are merged.

[0058] According to the current technical conditions, the functional activities are assigned to specific structures. The "loading load" function is assigned to the "rocket body structure"; the "providing thrust" function is assigned to the "power system"; the "guidance" and "controlling attitude" functions are assigned to the "control system"; the "telemetry data" function is assigned to the "telemetry system"; the "external measurement data" function is assigned to the "external measurement system"; and the "safety control" function is assigned to the "safety system". The composition of the rocket system structure can be known based on the functional allocation.

[0059] Step 4: Based on the rocket system structure composition results, perform architecture design in MBSE, including determining the system composition results included in the rocket system architecture, and establishing associations between the various systems included in the rocket system architecture, and on this basis, form multiple rocket system architecture design schemes.

[0060] The architecture design phase uses the function allocation results as input to define the structural composition of the rocket system and the interactions between its components. Finally, multiple design schemes that meet the index requirements are obtained through structural selection and design.

[0061] First, based on the functional analysis results and combined with the current technical conditions, the rocket system structure is obtained and the rocket system architecture is defined using a module definition diagram. The rocket system includes the rocket body structure, power system, control system, telemetry system, external measurement system, and safety system, and its weight and cost design parameters are defined.

[0062] Then use the internal module diagram to define the interfaces between the structures and their interactions. For example, the rocket body system is connected to the external measurement system, telemetry system and safety system respectively, the telemetry system and the external measurement system are both connected to the power system, and the control system is connected to the safety system and the power system.

[0063] Finally, based on the rocket system architecture and combined with existing examples, the six modules of "rocket body structure", "power system", "control system", "telemetry system", "telemetry system" and "safety system" were designed, and multiple rocket system design schemes were obtained, which were expressed using the "instance" element. Three schemes were designed, and each scheme selected a different structural composition.

[0064] Step 5: Output the multiple rocket system architecture design schemes obtained in step 4 from MBSE, convert them into Python code, and evaluate the multiple rocket system architecture design schemes. In other words, the multiple design schemes obtained in the architecture design phase are weighed and evaluated based on the evaluation criteria.

[0065] Python is a high-level programming language that is concise, clear, and readable. It is widely used in various fields, such as data science and artificial intelligence, and is suitable for multi-criteria comprehensive trade-off evaluation of multiple solutions. Therefore, combining SysML with Python in the system design phase to carry out multi-criteria trade-off evaluation of system design solutions can help designers quickly obtain better solutions and improve system development efficiency. In this way, SysML and Python can play their respective advantages and meet the needs of system design modeling and multi-criteria evaluation.

[0066] System designers first use SysML to complete system forward design and obtain multiple system design schemes. Then they use the rules for converting SysML models into corresponding Python codes to convert SysML models into Python codes. They use the analysis capabilities of Python scripts to conduct multi-criteria comprehensive trade-off evaluations on multiple design schemes, and finally obtain a better system design scheme, thereby improving system development efficiency.

[0067] Use the written software to convert the model into a code script according to the mapping relationship. In one embodiment, the rocket system design scheme can be converted into Python code based on the mapping relationship between SysML2.0 language and Python language. Select the scheme to be evaluated and generate the Python evaluation code for the scheme to be evaluated. The generated evaluation code mainly includes 3 parts. The first part is the class declaration code: use the python keyword class to declare the system, define the value of the class according to the system composition, and the composition. The second part is the instantiation code: instantiate the above class and assign the initial value according to the default value of the SysML model. The third part is the evaluation code: write the evaluation and analysis code according to business needs, you can directly edit the Python script in the script editing window or import the edited Python script, and then perform a multi-criteria comprehensive trade-off evaluation based on the various evaluation indicators of the design scheme, and call the numpy library to display the results as radar charts and bar charts.

[0068] Evaluation results such as Figure 2 As shown. The radar chart mainly compares and evaluates the cost, quality, flight speed and thrust of each design scheme, and the bar chart evaluates the cost performance of each scheme. Scheme B has the highest cost performance, so Scheme B can be selected as the final scheme output.

[0069] Although the present invention is disclosed as above in the form of a preferred embodiment, it is not intended to limit the present invention. Any person skilled in the art may make possible changes and modifications without departing from the spirit and scope of the present invention. Therefore, the scope of protection of the present invention shall be based on the scope defined by the claims of the present invention.

Claims

1. A system modeling and evaluation method based on MBSE, characterized in that: include: Perform requirements analysis on the rocket system and create SysML requirements diagram in MBSE based on the requirements analysis results; Create a use case for the rocket system and decompose it into sub-use cases. Create associations between the requirements analysis results, sub-use cases, and external objects that interact with the rocket system. The external objects are used to trigger the sub-use cases. The requirements corresponding to the sub-use cases are indicated by the requirement-use case association relationship. Perform functional analysis on the rocket system to obtain the functional activity diagram, further decompose and merge the functional activity diagram in MBSE, and assign the functional activities to specific structures to form the rocket system structure composition result; According to the rocket system structure composition results, the architecture design is performed in MBSE, including determining the system composition results included in the rocket system architecture, and establishing associations between the various systems included in the rocket system architecture, on this basis forming multiple rocket system architecture design schemes; Output multiple rocket system architecture design schemes from MBSE and convert them into Python code to evaluate multiple rocket system architecture design schemes.

2. The method according to claim 1, characterized in that The requirements analysis of the rocket system is performed, including: Sort out the rocket system development requirement items and divide the requirements into functional requirements and non-functional requirements; the functional requirements include at least: propulsion requirements, transportation requirements, control requirements and safety requirements; the non-functional requirements include at least: interface requirements, economic requirements and weight requirements; enter the requirement items stored in the document into the requirement table, the table header contains name and comments, which include the requirement number, name and comments respectively.

3. The method according to claim 2, characterized in that The SysML requirement diagram is established in MBSE according to the requirement analysis results, including: Create a SysML requirement diagram based on the requirement items. Id represents the number of the requirement, and Text represents the description of the requirement, that is, the comments in the requirement table.

4. The method according to claim 1, characterized in that The rocket system includes two use cases: launch and flight. The launch use case includes two sub-use cases: ignition and transportation. The flight use case includes two sub-use cases: navigation and payload release. The external objects that interact with the rocket system include operators and payloads. Use association tools to associate the operator with the ignition use case, and the payload with the transportation and payload release use cases, making it clear that the use case scenario is triggered by the operator and payload. Associate the propulsion and transportation requirements with the launch and transportation use cases, and establish an association relationship between requirements and use cases.

5. The method according to claim 1, characterized in that The functional analysis of the rocket system is performed, including: For the rocket system use case, use activity diagrams to analyze the behavior principles of the rocket system to achieve its functions and build a functional activity diagram for the rocket system, including launch, flight, and fall; The functional activity diagram is further refined and decomposed. By subdividing the functional activities at different levels, the system functional activities are decomposed step by step. The launch functional activities are refined into: loading payload, providing thrust, and safety control; the flight functional activities are refined into: providing thrust, guidance, controlling attitude, telemetry data, external measurement data, and safety control; Combine the thrust providing and safety control functions of both launch and flight activities; According to the current technical conditions, functional activities are assigned to specific structures. The load-carrying function is assigned to the rocket body structure; the thrust-providing function is assigned to the power system; the guidance and attitude control function is assigned to the control system; the telemetry data function is assigned to the telemetry system; the external measurement data function is assigned to the external measurement system; and the safety control function is assigned to the safety system. The structural composition of the rocket system is determined according to the functional allocation, including the rocket body structure, power system, control system, telemetry system, external measurement system and safety system.

6. The method according to claim 1, characterized in that According to the rocket system structure composition results, the architecture design is performed in MBSE, including: According to the functional analysis results and combined with the current technical conditions, the rocket system structure is obtained and the rocket system architecture is defined using the module definition diagram, and its weight and cost design parameters are defined; Use internal module diagrams to define interfaces and interactions between structures, where the rocket body system is connected to the external measurement system, telemetry system, and safety system, respectively; the telemetry system and external measurement system are both connected to the power system; and the control system is connected to the safety system and power system; Based on the rocket system architecture and combined with existing examples, six modules including rocket body structure, power system, control system, telemetry system, telemetry system and safety system are designed, and multiple rocket system design schemes are obtained and expressed using example elements.

7. The method according to claim 1, characterized in that The output of multiple rocket system architecture design schemes from MBSE and the evaluation of multiple rocket system architecture design schemes after conversion into Python code include: Based on the mapping relationship between SysML2.0 and Python, determine the conversion relationship between rocket system design scheme and Python code; Select the solution to be evaluated and generate the Python evaluation code for the solution to be evaluated; A multi-criteria comprehensive trade-off evaluation is performed based on the various evaluation indicators of the design scheme, and the numpy library is called to display the results as radar charts and bar charts.

8. The method according to claim 7, characterized in that The Python evaluation code includes: The first part is the class declaration code: use the Python keyword class to declare the system, and define the value and composition of the class according to the system composition; The second part is the instantiation code: instantiate the above class and assign initial values ​​according to the default values ​​of the SysML model; The third part is the evaluation code: write the evaluation analysis code according to business needs, directly edit the Python script in the script editing window or import the edited Python script.

9. The method according to claim 7, characterized in that: Radar charts are used to compare and evaluate cost, quality, flight speed and thrust, while bar charts are used to evaluate cost-effectiveness.

10. A computer program product, characterized in that When the computer program product is executed by a processor, the steps of the MBSE-based system modeling and evaluation method described in any one of claims 1 to 9 are implemented.

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