1、_ SAE Technical Standards Board Rules provide that: “This report is published by SAE to advance the state of technical and engineering sciences. The use of this report is entirely voluntary, and its applicability and suitability for any particular use, including any patent infringement arising there
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4、0 (outside USA) Fax: 724-776-0790 Email: CustomerServicesae.org SAE WEB ADDRESS: http:/www.sae.org SAE values your input. To provide feedback on this Technical Report, please visit http:/www.sae.org/technical/standards/J2998_201401 SURFACE VEHICLE RECOMMENDED PRACTICE J2998 JAN2014 Issued 2014-01 Mo
5、del Description Documentation Recommended Practice for Ground Vehicle System and Subsystem Simulation RATIONALE Increased use of dynamical modeling and simulation for engineering development and testing of the functional performance of ground vehicles has resulted in a need for standardizing documen
6、tation of the dynamical models used. Multi-disciplinary global engineering teams spanning domains within organizations and collaborations between commercial businesses (OEMs and suppliers), government agencies, and research institutions often need to support usage of simulation models of entire grou
7、nd vehicle systems and/or related subsystems. This requires a minimum level of model documentation to efficiently facilitate, integrate, and manage modeling and simulation work activities. Specifically, model documentation is essential to permit exchange and development of models as well as applicat
8、ion and management of modeling and simulation processes. The recommended practice for model description documentation presented in this technical report will help to: (1) create a common language, (2) increase productivity of processes, (3) promote uniform testing, and (4) reduce costs. FOREWORD Dyn
9、amical modeling as part of enterprise-wide and/or industry-wide engineering processes requires different types of documentation to support different engineering functions for model development, application, and management. These functions require both unique and common information about a model. In
10、addition, to protect intellectual property and sensitive information, different levels of documentation are required for engineering collaboration functions internally within a company, externally between companies, and globally for internal and external work across national borders. Specifically, M
11、odel Description Documentation (MDD) is needed for the following four categories of work functions: 1. Model users and simulation analysts from different disciplines apply models for various engineering tasks. For sharing and reusing existing models, they require a high level overview description to
12、 select an appropriate model with the capabilities, features, and performance required for their specific analysis purposes. 2. Model developers or producers (Simulation Modelers/Developers/Providers/Suppliers) create new models or maintain, integrate, and modify existing models. To develop new mode
13、ls, they need to receive documentation that specifies the requirements for the model to enable an intended analysis to be performed. They also need to provide documentation for users to understand and apply the models that they develop. In addition, they use model documentation to maintain models. T
14、o maintain, enhance, and continuously improve the existing models, they require more detailed information about the physical principles, equations, assumptions, and approximations used. 3 Simulation model requestors are model users and simulation analysts, who require new or improved models to perfo
15、rm specific engineering analysis functions for which models do not exist or are inadequate. To request new models or improved models, they need to supply or provide documentation that specifies the requirements for the model to enable an intended analysis to be performed. SAE INTERNATIONAL J2998 Iss
16、ued JAN2014 Page 2 of 116 4. Modeling and simulation process management controllers require documentation to control the introduction, update, and removal of models from libraries of models available for standard engineering analysis. They ensure that the models are thoroughly tested, documented, an
17、d meet required performance measures before they are accepted for use in standard engineering analysis work activities. To guarantee quality of simulation results, they need information about model documentation, performance, verification, validation, change history, and theoretical basis. TABLE OF
18、CONTENTS 1. SCOPE 3 1.1 Purpose . 3 2. REFERENCES 3 2.1 Related Publications . 3 2.1.1 SAE Publications . 3 3. DEFINITIONS . 4 4. MODEL DESCRIPTION DOCUMENTATION INFORMATION 8 4.1 Use Cases . 8 4.2 Documenting a Model . 9 4.2.1 Overview . 9 4.2.2 Process for Documenting a Model 9 5. RECOMMENDED INFO
19、RMATION FOR DOCUMENTING A MODEL 10 5.1 Overview . 10 5.2 Definition and Description of Model Documentation Content Items . 11 6. NOTES 20 6.1 Marginal Indicia . 20 APPENDIX A. MODEL DESCRIPTION DOCUMENTATION LIST OF SECTION HEADINGS . 21 APPENDIX B SUMMARY MATRIX OF CONTENT ITEMS INCLUDED IN EACH US
20、E CASE 24 APPENDIX C MODEL DESCRIPTION DOCUMENTATION USE CASE TEMPLATES . 41 APPENDIX D MODEL TECHNICAL SPECIFICATION DOCUMENTATION (USE CASE #7) EXAMPLE . 95 SAE INTERNATIONAL J2998 Issued JAN2014 Page 3 of 116 1. SCOPE The Model Description Documentation Recommended Practice for Ground Vehicle Sys
21、tem and Subsystem Simulation defines the recommended information content to be included for documenting dynamical models used for simulation of ground vehicle systems. It describes the information that should be compiled to describe a model for the following user applications or use cases: (1) excha
22、nge, promotion, and selection; (2) creation requests; (3) development process management; (4) compatibility evaluation, (5) testing-in-the-loop simulations with hardware and/or software; (6) simulation applications; and (7) development and maintenance. For each use case, a Model Description Document
23、ation (MDD) template is provided in the appendices to facilitate model documentation. In addition, an example of a completed model documentation template is provided in the appendices. 1.1 Purpose The purpose of producing standards for documentation of models is to: 1. Facilitate model sharing, reus
24、e, acceptance, and marketing of existing models for collaboration between disciplines, throughout a company, and across the industry by providing a concise and consistent description of the features and capabilities of a model to reduce model development time, cost, and duplication of efforts. 2. Pr
25、ovide understanding of the methods, assumptions, limitations, and approximations used to mathematically describe a dynamical system in terms of physical phenomena or behavior and capabilities of a model to prevent or reduce model misuse. 3. Enable models to be judged for usability, reuse, and compat
26、ibility with other models or for other engineering analysis applications. 4. Standardize methods for communicating, understanding, requesting, or specifying the performance, capabilities, applicability, and requirements of a model. 5. Facilitate storage of technical information required for work con
27、tinuity and incremental development (or continuous improvement) between different model developers to simplify the maintenance of models for modifications and updates. 6. Support modeling process quality, management, and standards such as ISO 26262, if using a Model-Based Design/Development process
28、as part of a product development process. 7. Promote the development of more well-thought-out, appropriate, and better quality models. 2. REFERENCES 2.1 Related Publications The following publications are provided for information purposes only and are not a required part of this SAE Technical Report
29、. 2.1.1 SAE Publications Available from SAE International, 400 Commonwealth Drive, Warrendale, PA 15096-0001, Tel: 877-606-7323 (inside USA and Canada) or 724-776-4970 (outside USA), www.sae.org. SAE Ground Vehicle Standards Committee Handbook, SAE International, March 2008. SAE J2546 Model Specific
30、ation Process Standard SAE Technical Standards Board Standard TSB003: “Rules for SAE Use of SI (Metric) Units”, SAE International, June 1992. SAE INTERNATIONAL J2998 Issued JAN2014 Page 4 of 116 3. DEFINITIONS 3.1 BACKWARD SIMULATION MODEL A model that progresses backward in time, using outputs to c
31、alculate the inputs required to achieve the output over a desired time interval. 3.2 CALIBRATION The process of determining a set of model parameters required for a model to represent or characterize the behavior of a specific hardware, algorithm or software. For a control algorithm, it is also the
32、process of adjusting the parameters of an algorithm model achieve a specific performance objective. 3.3 COMPONENT One part of the collection of parts that are assembled or integrated together to form a system or subsystem. 3.4 DYNAMICAL FUNCTIONAL MODEL (or FUNCTIONAL MODEL) A mathematical simulatio
33、n model of a piece of hardware, algorithm or software that describes how the fundamental variables change with time. It describes the operation or behavior of the variables. The model may or may not represent the physical structure of the hardware and its connection to other components. 3.5 DYNAMICA
34、L PHYSICAL MODEL (or PHYSICAL MODEL) A mathematical simulation model of a piece of hardware that describes how the fundamental physical variables change with time, while simultaneously capturing the physical structure of the hardware components and their interconnections in a schematic diagram that
35、is similar to an electric circuit model. The model provides the functional behavior of the physical variables and a diagram that is a visual representation or schematic of the physical hardware, which is made from models of individual hardware components and their hardware connections to each other.
36、 Thus, the model diagram visually provides additional information about the construction and purpose of the physical hardware system represented by the model. Hence, dynamical physical models are a subset of dynamical functional models. 3.6 EMBEDDED BLACK-BOX MODEL A model that is provided as an exe
37、cutable model with only a high level description of functionality and capabilities defined to enable its usage. The details of the model are considered as proprietary intellectual property, so no details of model structure, equations or physical principles are provided. This model could be in the fo
38、rm of an executable file. 3.7 FIDELITY1The degree to which a representation, such as a model, captures the nature of the real object being represented. 3.8 FORWARD SIMULATION MODEL A model that progresses forward in time using inputs to calculate outputs. 1SAE Ground Vehicle Standard J2546:”Model Sp
39、ecification Process Standard”, SAE International, February 2002. SAE INTERNATIONAL J2998 Issued JAN2014 Page 5 of 116 3.9 GROUND VEHICLE SYSTEM DYNAMICAL MODEL A mathematical simulation model of the functional operation of a ground vehicle that describes how its fundamental physical variables change
40、 with time, including transients. 3.10 INTERCHANGEABILITY2The “ability of a system or product to be compatible with or to be used in place of other systems or products without special effort by the user”. 3.11 INTEROPERABILITY The “ability of a system or a product to work with other systems or produ
41、cts without special effort on the part of the customer. Interoperability is made possible by the implementation of standards.”3It should be noted the customer is the end user of a model. It is also a property of models that allows models developed with different tools to function together. It is ena
42、bled by compiler tools that can produce a different implementation of the model. It can also be enabled by co-simulation tools that integrate and control the simulation of models running in different simulation tools. 3.12 LEVEL(N) SUBSYSTEM (or NTH-LEVEL SUBSYSTEM) A coordinated assembly of interco
43、nnected components operating together to perform a function or functions that provide part of the functionality of a level-(n-1) subsystem (i.e. the next level higher subsystem). 3.13 MODEL COMPATIBILITY The property of a model to guarantee that it will work with other models. The compatibility of a
44、 model with another model means that the models were designed to work together and to connect with each other, such as an engine with special technologies requires models of special sensors and actuators, and a model of controller software that can read these special sensors and control the actuator
45、s to operate. 3.14 MODEL ICON A picture or graphical representation of the function that the model describes. The icon can be used in addition or in place of the graphical block symbol used to represent a system, subsystem or component in a block diagram of the model. The icon provides a quick visua
46、l method for conveying the function that a modeling block describes. Inclusion of icons with modeling blocks can improve the high-level comprehension of a model without requiring a detailed review of the internal structure of the model. 3.15 MODEL MODULE A self-contained subsection or part of a mode
47、l that performs a specific standardized function, for easy assembly, flexible integration, and reuse with other model modules to form more complex models of whole components, subsystems, and systems. Some examples of model modules, which can be interconnected to form more complex models, are: (1) su
48、bsystems used to form a system, (2) subsystems used to form larger subsystems, (3) components used to form a subsystem, and (4) math functions used to form components. See the separate definition of SUBSYSTEM given below. 2Ground Vehicle Standards Committee Handbook, p.40, SAE International, March 2
49、008. 3Ground Vehicle Standards Committee Handbook, p 40, SAE International, March 2008. SAE INTERNATIONAL J2998 Issued JAN2014 Page 6 of 116 3.16 MODEL PLAYABILITY The ability of a model to work or function correctly in any simulation tool environment without requiring any additional processing or modification to the model. 3.17 MODEL PLUGABILITY A property of models that follow the same conventions or syntax; so, they can be connected togethe
