Sandy Friedenthal, father of SysML, talks about MBSE(Model-based System Engineering) and SysML. (Interviewed by CTO of Astah, Kenji Hiranabe)

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Kenji: Today I am with Sandy Friedenthal, who is an independent consultant in MBSE(Model-based Systems Engineering). He previously worked at Lockheed Martin, a large aerospace corporation, where he was responsible for advancing the practice of model-based systems engineering across the company.

He was a leader of the effort to develop the OMG Systems Modeling Language (SysML), and is co-author of ‘A Practical Guide to SysML’. He also is cochair of the INCOSE Model-based Systems Engineering initiative.

A pratcical guide to SysML

How does model-based systems engineering relate to systems engineering?

Sandy: Systems engineering (SE) is a multi-disciplinary approach to ensure the pieces of the system work together as to achieve the objectives of the whole. Each engineering discipline, such as software, mechanical, and electrical engineering, focus on their discipline specific aspects of the system, whereas SE address aspects of the system that span across the other disciplines and subsystems to ensure a balanced system solution that addresses the customer needs.

Model-based systems engineering (MBSE) is systems engineering with models. The system models are a primary artifact that are managed and controlled throughout the development process. Although there are many different kinds of models, emphasis is placed on the system architecture model to help integrate the various aspects of the system together.

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Sandy: MBSE is often contrasted with more traditional document based approaches to systems engineering.

In a document based approach, the systems engineering data is often contained in traditional documentation such as text specifications, spreadsheets, and powerpoint slides.
The information about the system requirements and high level design is spread across many different documents, and is difficult to maintain and ensure consistency. In MBSE, this same information is captured more formally in a system model, which enables the information to be more consistent, traceable, and more precise.

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How does SysML relate to MBSE?

Sandy: SysML is a graphical modeling language, and is a key enabler of MBSE. It is sometimes called a descriptive modeling language that is used to describe multiple views of the system architecture. This contrasts with analytical models such as Simulink, or geometric models used in CAD. However, the architecture model is intended to be integrated with other analytical and geometric models, typically through third part plugins in a system modeling tool

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Essential aspects of an MBSE approach?

Sandy: A practitioner of MBSE must learn the modeling language, the modeling tool, and the MBSE method used to perform systems engineering. This of course must augment the domain specific knowledge required for the system you are designing.

An organization that wishes to adopt MBSE must develop the infrastructure that includes the tools, methods, and training, and provide skilled people, tools, and processes to the projects for them to implement MBSE.

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How to start MBSE?

Sandy: There are few essentials to get started.
First, an organization needs a sponsor and a technical advocate who can lead this initiative.
It is often advantageous to integrate this effort with other existing improvement initiatives where this makes sense.

As a starting point, it is important to understand the current practice and systemic issues that MBSE may be able to address. It is important to clearly determine and document the motivation for why you are doing MBSE in your organization.
The key stakeholders should then develop a strategy and plan for their MBSE approach to address these issues. This plan includes the activities to incrementally develop the infrastructure and deploy this capability to projects. The results should be evaluated as a basis for continuous improvement.