Tuesday, December 22, 2009

Systems Engineering - A Description

Systems Engineering is a structured approach to the development of complex, engineered systems.

The Whole System Approach
·         Top-down design, optimizing for system effectiveness not necessarily component effectiveness.
o   E.g. Metallic structures on spacecraft can magnify radiation hazards. Metal may be the best choice for the frame component, but may not be the best choice for the system.
·         Design the right system.
·         Systems design is inherently interdisciplinary. Systems Engineers must possess and cultivate broad technical knowledge.
·         Manage subsystem interactions.

Project Management
·         Manage cost, resource utilization, and scheduling constraints from an engineering standpoint.
·         Collect voice of customer, communicate with stakeholders, manage and coordinate suppliers.
·         Prepare and maintain a current Systems Engineering Management Plan (SEMP) as the primary controlling document for all system development activities.

The Iterative Design and Evaluation Method
·         The Systems Engineering method is an iterative process by which a system concept is developed and refined with continual evaluation against requirements, until a completed and functional system design is produced that meets the goals established for the system.
  • The steps in the Systems Engineering method include:
1.       Develop system performance and cost requirements.
2.       Develop multiple system concepts that can satisfy most or all of the requirements.
3.       Select a concept and begin the design/evaluation loop.
a.       At the outset of the design/evaluation loop, the system concept has poor definition. Each pass through the loop increases the detail of the design.
b.      Also, at the outset there are many risks and unknowns. As the detail is added to the design, frequent evaluation of the design through testing and simulation identifies problems that are then corrected in subsequent design iterations. In this way risk is diminished on each pass through the loop
c.       The design/evaluation loop concludes when a system design that satisfies the performance and cost requirements is complete, and when all risks relevant to the design have been abated or effectively managed.
4.       Produce and implement the system.

Risk Management
·         Systems design carries risk inherently. Consequently, risk management is an important part of the Systems Engineering method.
·         Some common systems risks are:
o   Interdependencies between subsystems magnify effects of point failures.
o   Complex system behavior may be difficult to model or predict (greater than the sum of its parts).
o   System dynamics are strongly characterized by bottlenecks, load variations, and feedback loops.
o   New failure modes arise due to novel design, new technology, or increased complexity.

Interface Design
·         The Systems Engineer (or team) is wholly responsible for the specification and design of interfaces.
o   Create and maintain current Interface Control Documents (ICDs) for all system interfaces.
·         Interfaces carry material, information and energy between components. Interface types include:
o   Mechanical
o   Electrical
o   Data
·         Interfaces are loaded junctions exposed to hazards from more than one direction.
·         Interfaces are sensitive to peak loads, and are natural bottlenecks that can limit system performance.
·         Interfaces can be the source of unintended feedback loops.
·         The more complex a system is the more critical interface design becomes.

UPDATE - Presentation available here.

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