Element | Purpose |
---|---|
Variable | Represents the quantities and units for Part attributes, Action inputs/outputs, and Interface connections. |
Requirement | Definition of a customer or system-level need. Includes assigned systems, functions, owner(s), and quantitative constraints that determine verification status |
Part | Structural / spatial / logical unit or block. Can be decomposed indefinitely to build a hierarchical system structure. |
Port | Attach to Parts to represent an inlet or outlet. |
State | Represents the different “modes” or states your system can be in; assignable under any Part. |
Action | Represents the different actions your system can perform; assignable under any Part. |
Interface | Connect two Ports together to represent physical contact. Interfaces can contain multiple connections, each of which represents a flow of information, mass, energy, or force. |
Transition | Connect two States together. Defines the conditions under which the transition is triggered and which Actions get executed when triggered. |
Signal | Connects Actions together to represent a sequence. Propagates output Variables to inputs and triggers the next Action to execute. |
Function | Represents an abstract capability in the functional decomposition hierarchy; independent of physical architecture and assignable to Requirements and Parts. |
1 + 2*(43^5)
, and can also reference other variables by name, i.e. total_mass = mass1 + mass2
.
level
– abstraction level of the need (mission, system, subsystem, component)name
– short, human-readable titlestatement
– the text of the requirement expressed as a shall/should clauseconstraints
– a list of quantitative checks such as mass < 100 kg
. Each constraint references one Variable, an operator (<
, >
, =
, <=
, >=
), and a limit (numeric value + optional unit).status
– verification state automatically derived from the constraints (e.g., complete when every constraint is true, failed when any constraint is false, in progress when one or more referenced variables lack a value)mass < 100 kg
, evaluate to true or false. Constraints are evaluated continuously as their reference Variable changes, i.e. mass
.Figure 1. Structural decomposition of the Griffin SV satellite
Figure 2. Example ports on Griffin SV and their connection to mission control centers
Field | Description |
---|---|
Type | Matter, Information, Energy, or Binding |
Direction | Flow orientation relative to the owning Part (e.g. in, out, both) |
Subtype | Optional subtype (e.g.) Ethernet, O2 gas, Electrical |
Variable | The numeric value and unit (e.g. 2 kg/s, 28 V) |
Properties | (Optional) list of variables to further define the connection (e.g., 128 kHz, 5°C, 85 Pa) |
Figure 3. Interface connecting two Griffin SV subsystems
Figure 4. State machine of 'Rocket Engine'
Figure 5. 'Combustion' Action computes combustion pressure and chamber temperature of the Rocket Engine
Attribute | Purpose |
---|---|
level | Abstraction tier where the function lives (mission-0, system-1, subsystem-2, component-3) |
name | Short, human-readable title |
description | Plain-language explanation of what the function accomplishes |
failure modes | Explains ways the function can fail |
success criteria | Explains expected behavior / outputs |