Introduction To Systems Engineering
originated in 1986 at Motorola with credit for the name going to Motorola engineer Bill Smith. a statistical measurement (6σ) Minimizing variation and associated defects
"Six Sigma"
System Architecting
"The structure of components, their relationships, and the principles and guidelines governing their design and evolution over time"
Test failures can be caused by a fault in:
(1) System under test, which is the objective of the testing. (2) test procedures (3) test execution (4) test analysis (5) test equipment
Requirements Analysis, 2 parts
(1)Problem Definition Systems engineer must thoroughly analyze all requirements - Do they meet basic needs system is intended to satisfy - Are there ambiguities or inconsistencies in definition of required capabilities (2)Clarification, Correction and Quantification Modify and amplify to better represent objectives Interact with prospective users to understand needs/ constraints
Design Validation what is Tests and Test Data Analysis?
- All critical system characteristics need to be stressed beyond specified limits to identify weak areas. - Instrumentation must be precisely and reliably developed to locate deviations.
Objectives of the Needs Analysis Phase are
- to identify a valid operational need for a new system and, - to develop a feasible approach to meeting that need.
Physical Definition Synthesis of Alternative System Elements
-Decisions requiring physical form to implement functions Choice of media, element form, arrangement and interface designs -Trade-off analyses employed again
Engineering Development Systems engineering validates new technology, transforms the selected concept into hardware and software designs, and builds and tests production models.
1. Advanced Development: identifies areas of risk, reduces these risks through analysis, development, and test, and defines system development specifications (B-Spec); 2. Engineering Design: performs preliminary and final design and builds and tests hardware and software components, for example, configuration items (CIs); and 3. Integration and Evaluation: integrates components into a production proto- type, evaluates the prototype system, and rectifies deviations.
Three categories of interface elements
1. Connectors - facilitate transmission of interaction media between components; 2. Isolators - inhibit transmission of interaction media; 3. Converters - which alter the form of the interaction medium.Three categories of interface elements:
Concept Development Systems engineering establishes the system need, explores feasible concepts, and selects a preferred system concept. This stage may be subdivided into three phases:
1. Needs Analysis: defines and validates the need for a new system, demonstrates its feasibility, and defines system operational requirements; 2. Concept Exploration: explores feasible concepts and defines functional performance requirements; and 3. Concept Definition: examines alternative concepts, selects the preferred concept on the basis of performance, cost, schedule, and risk, and defines system functional specifications (A - Spec).
Context diagrams consist of three components:
1. The System - a single geographic figure - an oval, circle, or rectangle in the middle of figure with only name of the system within. No other information should be present. 2. External Entities - all entities with which the system will interact, including sources of inputs and destinations of outputs. 3. Interactions - between the external entities and the system are represented by arrows, with arrowheads representing the direction or flow of a particular interaction.
Level 2 WBS activities
1.1 System Product 1.2 System Support 1.3 System Testing 1.4 Project Management 1.5 Systems Engineering
Modular Configuration
:Define boundaries between components and subsystems so as to minimize their interactions (i.e., their dependence on one another).
Necessary
A condition A is said to be necessary for a condition B, if (and only if) the falsity of A guarantees (or brings about) the falsity of B. [www.sfu.ca] Air is necessary for human life.
Sufficient
A condition A is said to be sufficient for a condition B, if (and only if) the truth of A guarantees (or brings about) the truth of B. [www.sfu.ca] Air is not a sufficient condition for human life - need food, water etc. [www.sfu.ca]
Variation
A consistent aspect of daily life, such as the time it takes you to get to school based on speed, traffic lights, weather etc.
Modularity
A measure of degree of mutual independence of individual systems.
Utility Function Method
A refinement of the second method (Actual Measurement Method). Each criterion is measured, just as in the second method, but instead of allocating subjective values, a utility function maps a measurement (𝑚_𝑖 ) to a number between 0 and 1 (𝑢_𝑖 ):
Preplanned Product Improvement (P3I)
A strategy to proactively plan for future system upgrades
Major System Upgrades:Modernization 1 area that can hamper it and what must be done
Advances in Technology: Lead to a gradual decrease in the system's effective operational value. System Upgrade: Improvement to system's overall relative effectiveness by replacing a limited number of critical components in a few subsystems.
Identifying the Value Stream
All actions currently required to change a product or service to meet customer demand and expectations.
9.5 Trade-Off Analysis - Steps
Answer
Actual Measurement Method
Answer
Factors in decision-making process
Answer
Subjective value method
Answer
System Functional Specifications:
Answer
Other Key Lean Concepts - Takt time
Available production time divided by the rate of customer demand. Sets pace of production to match rate of customer demand.
Configuration Items (CIs)
Basic building block or element of a system that is basis of describing and formally controlling system design.
System test environment should:
Be as realistic as practicable. Anticipate conditions expected in operational test and evaluation.
System Acceptance Test
Before each production system is accepted by the customer for delivery, it must pass a formal _________
Variation can be classified based on causality: 2 types?
Chance causes are natural or random variations in a process. Assignable causes of variation are unnatural variations in a process
Other Requirement types and their focus
Compatibility : how the system interfaces with others Reliability, Maintainability, Availability (RAM): reliability of system, ease of maintenance, and support facility requirements Environmental: extreme physical environments system may see Affordability: acceptable (competitive) cost Useful life: capable of periodic modernization to avoid obsolescence - Pre-planned Product Improvement (P3I): growth capability explicitly planned for. User: user's needs and limitations - "user friendly" emphasis - Seek to understand in preproposal stage. Market surveys may assist. Operational availability: date to be ready for use and operating tempo
Key factors associated with development of Systems Engineering:
Competition - exert pressure to produce best performing, most affordable system in least possible time. Advancing Technology - provide opportunities for capability improvements, but also brings with it cost and risk. Solid state electronics - Automation Digital Computers - Robotics Specialization - partitioning of systems (and engineering disciplines) into building blocks that then must be integrated and interfaced with environment.
Operational T & E Execution:
Conducted primarily by user(s), or an independent testing organization Who have not been part of system development. Therefore, extensive training is typically required.
Critical Design Review (CDR):
Critical issues from PDR are addressed in _______ to evaluate actions taken to resolve. _______ usually examines the following for soundness and adequacy: Drawings Schematics Data flow diagrams Test plans Logistic supply plans
Creating Customer Value
Customers only want to pay for work that they think adds value (changes the form, fit, or function) to the end product or service.
Six Sigma Philosophy - DMAIC Model
DEFINE MEASURE ANALYZE IMPROVE CONTROL
Effort required for installing a delivered system at its operating site is strongly dependent on two factors:
Degree of integration that was accomplished at production facility Complexity of interfaces between the system and operating site.
Relentless pursuit of reducing variability in: Six Sigma - Business Strategy
Design Suppliers / vendors Processes Measurement
Validation
Determination that results accurately represent real world, to extent required for their intended use.
Verification
Determination that simulation results accurately represent the developer's conceptual description and specification.
Validation
Determination that simulation results accurately represent the real world, to the extent required for their intended use.
Engineering Design
During the ______________ phase, the design components are fit together to meet operational requirements, are reliable, maintainable, and safe under all conditions, are producible within established cost and schedule goals
Physical components are categorized as follows:
Electronic Electro-optical Electromechanical Mechanical Thermomechanical Software
Operational Knowledge
Essential that system engineers acquire a solid understanding of the conditions under which the system being developed will operate.
2 types of interfaces
External interfaces - occur at boundaries between system and environment. Internal interfaces - boundaries between individual components in a system.
Configuration Baselines - 3 types
Functional baseline -Describes system functional specifications -Derived from performance requirements Allocated baseline -System development specifications -Describes allocations of functions to system components (CIs). Product baseline -Products, process, and material specifications. -Established in terms of detailed design specifications.
2 methods of partitioning systems are by...
Functional elements - what function needs to be accomplished? [Processes] Physical components - what physical entity can perform the function? [Things]
Preliminary Design Review (PDR):
In government, _________ is conducted by acquisition agency to certify completion of preliminary design. ______ usually includes review of: Design requirements and specifications Major interfaces System -level trade - off studies. Risk areas Test plans Long-lead items Logistics support plans
What describes when resources continue to be added, and a point is reached where performance benefits are not worth the cost of the added resources
Law of diminishing returns
There are six general sources of variation in a process:
Manpower Machines Materials Methods Milieu (Environment) Measurement
" a physical, mathematical, or otherwise logical representation of a system entity, phenomenon, or process. "
Model
Design for Maintainability
Modular System Architecture: vital to facilitating repair of operational failures, periodic maintenance, and system upgrading. Replaceable Units: must be accessible, simply and safely replaceable, and part of logistic support supply. Test Points and Functions: to converge on failed unit quickly.
Two categories of system development approaches based on driving forces:
Needs - driven: a. characteristic of most defense/ gov't programs b. typically stems from a deficiency in current system capabilities. c. requires a feasible and affordable technical approach. Technology - driven: a. characteristic of most commercial system development b. stems from a major technological opportunity to better meet a need c. requires demonstration of practicality and marketability.
Eight Wastes of LEAN management
OVER-PRODUCTION: TRANSPORTATION WAITING INVENTORY PRODUCING DEFECTIVE PRODUCTS OVER-PROCESSING MOTION UNTAPPED CREATIVITY
Preliminary Design
Objective - demonstrate design: Conforms to performance and design specifications. Can be produced by existing methods within established constraints. Includes the bulk of the functional design effort. Provides a framework for the next step, detailed design.
Detailed Design
Objective - produce a complete description of total system. Effort required to produce detailed design of a component depends on its "maturity." For new components, prototypes are usually built and tested. For large systems, a massive engineering effort is required to produce all necessary plans, specifications, and drawings.
3 categories of Scope of Control
Operational -Practitioner level - engineers, analysts, testers and architects -Typically structured decisions based on procedures and algorithms Managerial -Management level -Primary level of SE decision making -Typically semi-structured decisions relying on policies and logic Strategic Planning -Executive or enterprise level -Typically unstructured decisions with cause and effect considerations -Example: investment decisions-
Three main categories of simulations
Operational - used to help define operational and performance requirements, to explore alternatives, and select a preferred concept Physical - model physical behavior of system elements in support engineering design Environmental - primarily used during test and evaluation to simulate system's environment
In-Service Support 2 areas
Operational Readiness Testing Logistics Support
system architectures have at least three system representations
Operational View — perspective of user or operator Logical View — perspective of customer or manager Physical View — perspective of designer
Sources of Operational Knowledge
Operational tests of similar systems Integration testing during system installation System readiness tests - helpful to observe: -Different operating modes of system -Start-up and shutdown procedures -How operators react to fault conditions Maintenance operations Experienced operators
Visual Control
Other Key Lean Concepts - Placement in plain view of all tools, parts, production activities, etc. (Andon Boards)
Additional methods to reduce risk
Parallel development efforts Alternative integration strategies Incremental development strategies Increase use of modeling and simulation Interface development and testing
Operational Readiness Testing
Periodic readiness checks of systems during their standby periods to ensure that they will operate at their full capability when required.
Test failures are usually due to causes other than the system under test. Frequently occurring problem areas are:
Personnel error Faulty test equipment or procedures. Misinterpretation of specifications Unrealistically tight tolerances
Postdevelopment Systems engineering produces and deploys the system and supports system operation and maintenance. This stage may be subdivided into two phases:
Production: develops tooling and manufactures system products, provides the system to the users, and facilitates initial operations; Operations and Support: supports system operation and maintenance, and develops and supports in-service updates.
System Acceptance Test - 3 things it must determine
Properly constructed Meets key requirements Is ready for operational use.
Three primary methods to reduce risk in Risk Reduction phase
Prototype development (both hardware and software) Identification of components requiring development Development testing of these components
Considerations for physical components:
Reliability Form and fit Maintainability Compatibility with operating environment Producibility Testability Safety Cost
Three types of components that frequently require development:
Required to have extended functional performance beyond previously demonstrated limits Perform highly complex functions. Interactions with their environment are imperfectly understood.
Types of Models
Schematic - convey relationships in diagrammatic form with common symbology. Mathematical - express system functionality and dependencies in language of mathematics. Physical - directly reflect physical characteristics of an actual system or element.
Objectives Tree: a single or small set of top - level objectives are decomposed into a set of primary and secondary objectives
See image
5S
Seiri - Sort and scrap Seiton - Straighten (organize and label for easy use) Seiso - Scrub or shine Seiketsu - Systemize (conduct daily) Shitsuke - Sustain (form a habit)
Concept Definition Phase is marked by 3 things
Serious, dedicated effort to define functional and physical characteristics of new system Commitment to characterize system in sufficient detail to quantitatively predict: - operational performance, - time of development, and - life cycle cost Level of effort sharply greater than previous phases
Functional elements are categorized by operating medium into four classes
Signal: sense, communicate and propagate info (e.g. radio signals) Data: interpret, organize and manipulate info - associated with analysis and decision making (e.g. computer programs) Material: provide structure and transformation of materials Energy: provide, convert or control energy or propulsive power
9.1 Decision Framework by Types / Categories Level of Structure 3 types of decisions?
Structured Context and scope is well established Supporting info and legacy decisions typically available Minimal processing necessary - routine Semi-structured Fall outside routine Circumstances differ from related decisions in past Many SE decisions in this category Unstructured Represent unique complex problems Often first-time or one-time decisions New technology decisions without much relevant legacy info
Analysis of Alternatives
Studies conducted to refine the operational requirements by modeling the interaction of operational scenarios.
3.2 Hierarchy of Complex Systems: List and describe the 5 areas that make up this
System (in context of this hierarchy discussion) engineered to performs significant useful service with only the aid of human operators and standard infrastructure Subsystems performs closely related subset functions of overall system major portion of system, involving several disciplines Components intermediate level of system elements transition between specialized subcomponents to complex subsystems Subcomponents Perform elementary functions composed of several parts Parts elements that require other parts to perform most come in standard sizes and are available commercially
Techniques to Increase Reliability
System Modularity - increase modularity of components to achieve loose coupling among components, and minimize components in series. Redundancy - Increase redundancy with parallel operating components, or with switches that automatically transfer operations to backup components. Multiple Functional Paths -or "channels of operation" within system design. Derating Components - using a component under stress conditions considerably below rated performance value to achieve a reliability margin.
2 parts of Concept Selection Step, name and describe them
System Performance, Schedule, and Cost: - Performance requirements are minimum baseline for a system, but should be evaluated to ensure they are essential (vice desirable). - Be cautious of overly optimistic schedule estimates. - Program costs should cover the full system life cycle. Life Cycle Cost Estimating: - Cost estimate for development, production, and operational support of proposed system is a required product of Concept Definition phase. - Similar tasks from previous projects are used to help derive costs - Competitors must work towards credible justification for costing.
Advantage of P3I is that changes are planned for in advance so that:
System design can accommodate changes with minimum reconfiguration; Upgrade process can proceed with minimum disruption to operations.
Configuration Management (CM)
System engineering process that maintains the continuity and integrity of the system design throughout system development.
Accuracy
Test Equipment must therefore meet exacting standards: (1/3) onputs and measurements should be several times more precise than tolerances on system element inputs and responses.
Reliability
Test Equipment must therefore meet exacting standards: (2/3) vital to minimize test discrepancies due to test equipment errors.
Flexibility
Test Equipment must therefore meet exacting standards: (3/3) test equipment should be designed to serve several purposes.
Risk Management
The methodology employed to identify and minimize risk in system development
LEAN Principles
Value, as defined by the customer Identify the Value Stream Make the process Flow Use customer Pull to initiate action Pursue Perfection
Critical Path Method (CPM)
What describes this? • Activities in WBS often used in network scheduling techniques. • Critical path analyses are conducted by looking at each major element of system and estimating durations required for each step of development, production and test. • The path requiring the longest time to complete is the "critical path."
Intelration and Evaluation Phase
What phase does this objective describe? Qualify engineering design of system for release to production and subsequent operational use. Assemble and integrate engineered components of new system into an effectively operating whole. Demonstrate system meets all operational requirements.
Lean Culture
When a _____________ exists, improvement is exponentially more likely to be sustained and an environment for continuous improvement is created.
A major product of Concept Definition phase is a set of plans to include:
Work Breakdown Structure (WBS) Life Cycle model and associated costing System development schedules Operational (or integrated logistic) support plan System Engineering Management Plan (SEMP)
Qualification testing
_________ - testing a production-level component ("first-unit" testing) prior to its delivery to integration facility. Ensures that final production design meets specifications. Concerned with whether component should be accepted. Concerned with exact conformance of unit to interface tolerances.
Lean
_________ is a people-oriented business philosophy that focuses on continuously enhancing the value of a product or service, and on eliminating waste from the value stream.
Development testing
_________ to validate design and maturity of components which: Are critical to system performance Are expected to operate at levels well above previous applications Are newly developed Will be highly stressed/ subject to extreme environmental conditions
Maintainability
a measure of the ease of accomplishing the functions required to maintain the system in a fully operable condition.
Measure of Effectiveness (MOE)
a qualitative or quantitative metric of a system's overall performance that indicates the degree to which it achieves its objectives under specified conditions.
Measure of Performance (MOP)
a quantitative metric of a system's characteristics or performance of a particular attribute or subsystem.
Producibility
denotes relative system production costs
A system design is used to:
develop system components build and integrate system components, and understand configuration changes as the system is modified.
A system architecture is used to:
discover and refine operational and functional requirements, to drive the system to a specific use or purpose, to discriminate between options, and to resolve make/buy decisions.
The most prevalent single driving force for new systems is
obsolescence
Why can obsolescence happen?
operating environment may change; the current system may become too expensive to maintain; the parts necessary for repair may be no longer available; competition may offer a much superior product; or technology may have advanced to the point where substantial improvements are available for the same or lower cost.
System Architecting
primarily involves developing different perspectives or architectural views of a complex system.
Reliability
probability that system will perform its functions correctly for a specified period of time under specified conditions.
System Engineers must observe production operations to acquire first-hand familiarity with
production tools, processes, materials, parts availability, and quality control.
Performance Requirements
refer largely to "how well" system should perform its requirements and affect its environment.
Functional Requirements
refer largely to "what" the system should do.
Operational Requirements
refer largely to mission and purpose of system
Physical Requirements
refer to characteristics and attributes of physical system and the physical constraints placed upon system design.
Availability
the probability that system will perform its function correctly when called upon.
Principal objective of Concept Exploration Phase
to convert operationally oriented view of system into an engineering oriented view.
Potential sources of program risk:
unproven technology, difficult to achieve performance requirements, severe environments, inadequate funding or staffing, and an unduly short schedule.
What is Work Breakdown Structure (WBS)
• A systematic organization of project tasks • Defines the whole system to be developed in terms of products and services to be accomplished in a hierarchical structure • Is refined and more fully articulated as system is developed • Provides a framework for implementation of the project
Purposes of SEMP
• Outlines engineering responsibilities and procedures • Compares planned tasks versus those accomplished
6 SEMP Elements
• Statements of work • Organization • Scheduling • Program reviews • Performance measures • Risk management