Requirements represent a bounding box of the product concept as a set limited by Stakeholder needs. They must be complete and consistent, which drives the use of tools like DOORS or Jama to formally manage the set. They must also be feasible and verifiable, which drives their incorporation into the Total System Model (TSM) where the requirements can be easily compared against the system specification as it develops.
Figure 1 shows a short, but representative list of requirements for our washing machine.
Figure 1 Washing Machine Requirements
Quick inspection shows that they fall into several categories
- Functional, e.g. separate cycles for different laundry types
- Non-functional, e.g. clean modern appearance
- Regulatory, e.g. UL certification
- Performance, e.g. 100 rpm spin cycles
The categories imply we need to create requirement structures or hierarchies. Different tools, however, handle these structures differently.
The Washing Machine – SysML and Requirements Management Tools
This creates the challenge. We need to have the requirements in a configuration-managed repository to formally manage them and we need to have them as part of the TSM so we can verify them. In each case, we need to structure them to preserve category organization and comparable structures must be maintained when they are transformed between domains.
Figure 2 Syndeia dashboard showing MagicDraw SysML (left column) and Windchill PLM (right column)
The MBE platform Syndeia supports several possible solutions. In one use case, the requirements structure in a requirements management tool is transformed into an equivalent structure in SysML, where both content and hierarchy are preserved. Figure 2 shows the Syndeia dashboard after such a model transform. The original Jama requirements repository, shown in the right column, is organized by Project, Component, Set and Requirement. The SysML requirements in MagicDraw, shown on the left, preserve both structure and attributes such as id, text and others.
As with the parts Bills-of-Materials in Part 1 of this series, a network of persistent connections between elements in the two tools allows the models to be compared and synced if they diverge during system development.
Figure 3 <<satisfy>> relationship matrix with requirements in rows and blocks (structural components) in columns
One advantage of bringing the requirements into SysML in such a model transformation is that a standard SysML relationship, <<satisfy>>, can be created to link requirements to structural parts or other model elements that satisfy them. Such relationships can be created and displayed in diagrams, tables or matrices, as in Figure 3.
In Part 1 of this series on our washing machine model, we created connections between MagicDraw SysML blocks and Windchill PLM parts. In Part 2 here, we have added connections between Jama requirements and MagicDraw SysML requirements, and also connections between SysML blocks and SysML requirements. We now have extended chains on connection running across three tools, connecting Jama requirements to Windchill parts via MagicDraw. Later we will look at ways to visualize and trace these chains, but first, in Part 3, we will add still more connections, to analysis models.
- MBE For Consumer Electronics | Part 1
- MBE For Consumer Electronics | Part 2 (this post)
- MBE For Consumer Electronics | Part 3 (coming soon)
- MBE For Consumer Electronics | Part 4 (coming soon)
- MBE For Consumer Electronics | Part 5 (coming soon)