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Processes

A systems engineering process is a formalised, planned, reviewed, and continually evolving series of activities which:

  • Involves multiple engineering disciplines working co-operatively together Involves the customer as intimately as possible in all phases Needs sophisticated communication of desires, expectations, needs, and engineering data Needs formalised notations for the individual problem domains within the project and, particularly, the interfaces between problem domains and between engineering disciplines Allows the engineering of a need into a reality

  • Can be thought of as the engineering of a requirements set into a finished system

The activities in the systems engineering process are focused on four major technical phases:

  • Requirements management System behavioural analysis Architecture analysis

  • System verification and validation

The first phase in such a process translates end-user, marketing, or customer source statements into formal requirements. In principle this is confined to a requirements capture exercise at the start of a project. In reality, it occurs throughout the lifecycle, drawing requirements from many sources.
Typical requirements analysis tasks include:

  • Identify source material Identify stakeholder needs Identify initial set of requirements (top-level functional, non-functional, performance and interface requirements) Establish design constraints Define effectiveness measures

  • Capture issues/risks/decisions

The main objectives of the next phase, the system functional or behavioural analysis, are to:

  • Describe the problem defined by the requirements analysis in clearer detail

  • Identify and describe the desired functional behaviour of each system element or process

This functional analysis is typically performed without consideration of a specific design solution. Key tasks of the functional analysis phase include:

  • Define operational scenarios Derive system behaviour model (and other models as needed) to reflect control and function sequencing, data flow and input/output definition Derive functional and performance requirements, and allocate to behaviour model

  • Define functional failure modes and effects.

The physical architecture analysis phase performs system synthesis by assigning functions to identified physical architecture elements (structures, subsystems, and components). This synthesis activity is performed for the purpose of defining design solutions and identifying subsystems and components that will satisfy the established requirements. Candidate tasks include:

  • Group and allocate functional behaviour among the system's component parts Define functional interfaces between system component parts Identify physical interfaces Ensure that performance requirements are preserved Allocate non-functional requirements Assess failure modes, effects and criticality

  • Identify make-or-buy alternatives

The technical evaluation phase of systems engineering demonstrates that the system performs as needed and as specified. The initial task is a comprehensive verification and validation analysis, which may include static and dynamic logic analyses, functional performance assessments, system simulation, hardware-in-the-loop testing, and so on. Other key tasks include:

  • Test planning Compliance and cost assessment Best design solution selection

  • Automatic report and specification generation

The nucleus for any sound systems engineering process is the Systems Engineering Management Plan (SEMP). This plan will describe the systems engineering strategy to be used for project planning, controlling and execution. The SEMP will identify all project deliverables to be produced, and the individual systems engineering tasks necessary to produce each of them.

3SL's Cradle tool environment provides the paradigm for the user to automatically develop and document the SEMP.

To accurately reflect an accepted systems engineering process, the SEMP follows current industry standards and methodologies. These include IEEE 1220-1998, Standard for Application and Management of the Systems Engineering Process; Electronic Industries Alliance (EIA) ANSI/EIA-632-98, Processes for Engineering a System; Systems Engineering Capability Maturity Model (SE-CMM), Carnegie Mellon Software Engineering Institute; and the soon to be released International Standards Organization (ISO) 15228, Systems Engineering Life Cycle Management.

Specifying and building responsive systems requires concise and up-to-date communications that involve the developers, end users, customers and stakeholders. Inadequate understanding or poor management of the system requirements creates additional work later in the project, when potential design errors must be corrected. The systems engineering process should embrace a rigorous communications structure that helps engineers from different disciplines work in productive teams. This communication structure is identified in the SEMP.