Understanding SysML

Why are we using SysML?

omgsysml.org describes SysML as this:

The OMG systems Modelling Language (OMG SysML) is a general-purpose graphical modelling language for specifying, analysing, designing, and verifying complex systems that may include hardware, software, information, personnel, procedures, and facilities.

That is a good description of SysML, however, the benefits of SysML are not mentioned. Specific benefits that an evolving SysML model can bring to a project are listed below:

  • Consolidated end-to-end definition with MBSE approach
  • Auto generation of deliverable content
  • Persistence post project
  • Information for promoting the relevant standards

Using SysML in conjunction with MBSE

SysML would be used to capture information in a model based Systems Engineering (MBSE) project.

Taking this approach enables the capture of:

  • Requirements /Operational Analysis
    • How they are implemented in functions
    • Who implements the functions
  • Functional Analysis
    • Functional specification
    • Declare the usage of methods
    • Understand where methods are used
  • Logical (Architecture) definition
    • The logical structure

  • Physical Definition

  • For each scenario:
    • Installed Capability/functionality
    • Installed Software
    • Which Requirements to verify

The image below relates to the above list. Requirement analysis elements are shown in blue, functional analysis in brown , logical structure in purple and physical definition objects are shown in green. The image shows how the elements in an MBSE project are linked together and how they feed back to the beginning of the process to ensure verification that the requirements have been satisfied. The aspect of this process that can be captured in SysML is identified as being on an orange background.

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Model Based Systems Engineering

Who uses the Model

  • Scenario Owners:
    • See how they are implemented
    • See requirement verification
  • Software Solution Providers:
    • Specifications of functions that are to be implemented in software
      • Shows where software is used in scenarios
  • Demonstration Organisers:
    • Define where each software solution is to be installed