Parametric Diagram

The SysML Parametric Diagram is a type of Internal Block Diagram (with some restrictions) that is used to model equation with parameters. They are an important tool that can be used to describe equations and their parameters and are important when performing trade off analysis and assessing design alternatives as they can be combined into systems of equations and related to Measures of Effectiveness MOEs.

Parametric diagrams describe the usage of constraint blocks and provide a mechanism for integrating engineering analysis such as performance and reliability and other factors of interest with other SysML models and diagrams.

Parametric diagrams define the way that constraint blocks are used to constrain the properties of another block. The usage of a constraint is said to bind the parameters of the constraint (e.g. F=m*a), such as F, m, and a, to specific properties of a block, such as a mass and acceleration, that provide values for the parameters.

Elements

The main elements that can appear in Parametric diagrams are:

• ConstraintProperty
• Property
• Objective Function
• Measure of Effectiveness

The main connectors  that can appear in Parametric diagrams are:

• Connector
• Binding Connector
• Item Flow
• Dependency

Tools

A variety of tools can be used with structural modeling and Internal Block diagrams, including:

• Modelica Integration - which provides a mechanism for simulation,
• Diagram Filters - which allows a user to filter elements out of the diagram to achieve a more specific focus,
• Pan and Zoom - which allows a modeler or viewer to easily move around large diagrams,
• Spreadsheet (CSV) Import and Export - which allows content in spreadsheets to be imported or exported from the model,
• Documentation - which allows formal or informal documentation to be generated from the model in a variety of formats,
• Traceability - which provides a hierarchical view of an element's relationships to other model elements,

Usage

The Parametric diagram can be used to show how the physical properties of a system are constrained by specifying a network of constraints that represent mathematical expressions such as {F=m*a} and {a=dv/dt}.

They can also be used for trade-off analysis, where a Constraint Block can define an objective function used to make a comparison between alternative solutions.

Critical performance parameters and their relationships to other parameters can be modeled, which can then be tracked throughout the system life cycle.