5 MEC 431: System Design
Overview of SE processes
Systems Engineering definition
• "System engineering is a robust approach to the design, creation, and
operation of systems. In simple terms, the approach consists of identification
and quantification of system goals, creation of alternative system design
concepts, performance of design trades, selection and implementation of the
best design, verification that the design is properly built and integrated, and
post-implementation assessment of how well the system meets (or met) the
goals.”— NASA Systems Engineering Handbook, 1995.
• "An interdisciplinary approach and means to enable the realization of
successful systems”— INCOSE handbook, 2004
What Is Systems Engineering?
• The function of systems engineering is to guide the engineering of complex
systems.
• And a system is defined as a set of interrelated components working together
toward a common objective.
• Furthermore, a complex engineered system is:
(1) composed of a multiplicity of intricately interrelated diverse
elements, and
(2) requires systems engineering to lead its development.
• The systems engineering viewpoint is focused on producing a successful
system that meets requirements and development objectives, is successful in
its operation in the field, and achieves its desired operating life.
• To achieve this definition of success, the systems engineer must balance
superior performance with affordability and schedule constraints.
• In fact, many aspects of systems engineering involve achieving a balance
among conflicting objectives. For example, the systems engineering typically:
(a) must apply new technology to the development of a new system while
managing the inherent risks that new technology poses.
(b) Throughout the development period, the systems engineer focuses his or
her perspective on the total system, making decisions based on the impacts
and capabilities of the system as a whole.
• What is system design
• There are three sets of common technical processes for Systems Engineering Processes
and Requirements: system design, product realization, and technical management.
• System Design Processes: Four system design processes used to define and baseline
stakeholder expectations, generate and baseline technical requirements, decompose
the requirements into logical and behavioral models, and convert the technical
requirements into a design solution that will satisfy the baselined stakeholder
expectations. These processes are applied to each product of the system structure
from the top of the structure to the bottom until the lowest products in any system
structure branch are defined to the point where they can be built, bought, or reused.
All other products in the system structure are realized by implementation or
integration.
• Product Realization Processes: The product realization processes are applied to each
operational/mission product in the system structure starting from the lowest level
product and working up to higher level integrated products. These processes are used
to create the design solution for each product (through buying, coding, building, or
reusing) and to verify, validate, and transition up to the next hierarchical level those
products that satisfy their design solutions and meet stakeholder expectations as a
function of the applicable life cycle phase.
• Technical Management Processes: The technical management processes are used to
establish and evolve technical plans for the project, to manage communication across
interfaces, to assess progress against the plans and requirements for the system
products or services, to control technical execution of the project through to
completion, and to aid in the decision-making process.
5 traits of the ideal systems engineer
1. An affinity for systems
2. Faculty of judgement
3. Creativity
4. Facility in human relations
5. Facility for expression
[REF: Arthur Hall “A Methodology for Systems Engineering”]
What is system design ?
• Systems engineering is the art and science of developing an operable system
capable of meeting requirements within often opposed constraints.
• Systems engineering is a holistic, integrative discipline, wherein the
contributions of structural engineers, electrical engineers, mechanism
designers, power engineers, human factors engineers, and many more
disciplines are evaluated and balanced, one against another, to produce a
coherent whole that is not dominated by the perspective of a single
discipline.
Systems Engineering Management
• Systems Engineering management
consists of:
• Development phasing controls the
design process and provides
baselines that coordinate design
efforts
• A systems engineering process
provides a structure for solving
design problems and tracking
requirements flow through the
design effort,
• Life cycle integration involves
customers in the design process and
ensures that the system developed
is viable throughout its life
Complex Engineering Systems Threshold
The characteristics of a system whose development, test, and application
require the practice of systems engineering are that the system:
(i) is an engineered product and hence satisfies a specified need,
(ii) consists of diverse components that have intricate relationships
with one another and hence is multidisciplinary and relatively
complex, and
(iii) uses advanced technology in ways that are central to the
performance of its primary functions and hence involves
development risk and often a relatively high cost.
System Building Blocks and Interfaces
• The need for a systems engineer to attain a broad knowledge of the several
interacting disciplines involved in the development of a complex system
raises the question of how deep that understanding needs to be.
• Clearly, it cannot be as deep as the knowledge possessed by the specialists
in these areas.
• However, it must be sufficient to recognize such factors as program risks,
technological performance limits, and interfacing requirements, and to
make trade - off analyses among design alternatives.
• To understand the scope of systems engineering and what a systems
engineer must learn in order to carry out the responsibilities involved in
guiding the engineering of a complex system, it is necessary to define the
general scope and structure of that system.
•
System building blocks are at the level of components and are the
basic building blocks of all engineered systems characterized by both
functional and physical attributes.
•
These building blocks are characterized by performing a distinct and
significant function and are singular — they are within the scope of a
single engineering discipline.
•
Functional elements are functional equivalents of components and
are categorized into four classes by operating medium:
- signal elements, which sense and communicate information;
- data elements, which interpret, organize, and manipulate
information;
- material elements, which provide structure and process material;
and
- energy elements, which provide energy or power.
•
Components are the physical embodiment of functional elements, which are
categorized into six classes by materials of construction:
- electronic,
- electro - optical,
- electromechanical,
- mechanical,
- thermomechanical, and
- software.
•
System building block models can be useful in:
- identifying actions capable of achieving operational outcomes,
- facilitating functional partitioning and definition,
- identifying subsystem and component interfaces, and
- visualizing the physical architecture of the system.
The System Environment
• The system environment, that is, everything outside the system that
interacts with it includes:
(1) system operators (part of system function but outside the delivered
system);
(2) maintenance, housing, and support systems;
(3) shipping, storage, and handling;
(4) weather and other physical environments; and
(5) threats.
Interfaces and Interactions
• Interfaces are a critical systems engineering concern, which effect
interactions between components and can be classified into three
categories:
(i) connect,
(ii) isolate, or
(iii) convert interactions.
• They require identification, specification, coordination, and control.
Complexity in Modern Systems
• Each system is always part of a larger entity. At times, this larger entity
can be classified as a separate system in itself.
• They tend to exhibit seven distinct characteristics:
- operational independence of the individual system,
- managerial independence of the individual system,
- geographic distribution,
- emergent behavior,
- evolutionary development,
- self - organization, and
- adaptation.
• Enterprise systems engineering is similar in complexity but focuses on an
organizational entity.
• Since an enterprise involves social systems as well as technical systems,
the complexity tends to become unpredictable.
What is Systems Engineering Management?
• The System Engineering Management function has the responsibility for
the design of the complete system’s architecture.
• It develops and maintains system requirements and its internal and
external interfaces.
• Systems engineering management interacts with all other activities of
the systems engineering process.
The functions of systems engineering management include:
• Planning and management of a fully integrated technical effort necessary to achieve
program objectives,
• Instituting and managing all necessary integrated product and process development
mechanisms to ensure that the information channels are always open, team activities
are coordinated, and the conflicts are resolved in a timely manner at the proper level,
• Ensure that a comprehensive and systematic "lessons learned" database is available to
guide the engineering process,
• Provide for the application of a systematic engineering approach for each phase of the
program from the concept definition to the design and deployment to the eventual
decommissioning of the system,
• Provide mechanisms to control and assess the progress by conducting technical
reviews, configuration Management, data and product management, interface
management, risk management, and test and verification, support analyses, trade
studies, modeling and simulation, prototyping, and research to help optimize system
design and minimize program risk,
• Support development of all necessary methods, processes, and data products to
ensure that the system can be built, tested, deployed, operated, supported, and
properly disposed of at the end of life
What Characterizes a Successful Systems Engineering Process ?
• The success of the systems engineering management can be measured by the
completeness and accuracy of the decision database and the degree of balance
among capabilities, cost, schedule, and risk in the system solution.
• The decision database includes:
o Trade-off and other analyses,
o Requirements and requirements allocations,
o Specifications,
o Verification requirements, and
o All the decisions made to arrive at the design,
o The design, and
o Traceability of design features to imposed specifications, requirements,
constraints, and standards.
System life cycle
A System Is …
• Simply stated, a system is an integrated composite of
people, products, and processes that provide a capability
to satisfy a stated need or objective.
Systems Engineering Is…
• Systems engineering consists of two significant
disciplines: the technical knowledge domain in which the
systems engineer operates, and systems engineering
management.
Systems Engineering through the System Life Cycle
• A major system development program is an extended complex effort to satisfy
an important user need.
• It involves multiple disciplines and applies new technology, requires
progressively increasing commitment of resources, and is conducted in a
stepwise manner to a specified schedule and budget.
System Life Cycle
The system life cycle may be divided into three major stages:
(i) Concept Development
(ii) Engineering Development
(iii) Post-development
Overview of SE processes
System Life Cycle Model
(i) Concept Development. Systems engineering establishes the system need, explores
feasible concepts, and selects a preferred system concept. The concept
development stage may be further 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).
HOMEWORK – Explore Engineering Development & Postdevelopment aspects …
The Systems Engineering Method
• The systems engineering method involves four basic steps:
• 1. Requirements Analysis — identifies why requirements are needed,
• 2. Functional Definition — translates requirements into functions,
• 3. Physical Definition — synthesizes alternative physical implementations, and
• 4. Design Validation — models the system environment
Requirements Analysis
Activities comprising the needs analysis phase are the following:
• Operations Analysis — understanding the needs for a new system;
• Functional Analysis — deriving functions required to accomplish operations;
• Feasibility Definition — visualizing a feasible implementation approach; and
• Needs Validation — demonstrating cost - effectiveness.
Functional Analysis
• Initial system functions are identified and organized that will achieve
operational objectives. These functions are vetted through analysis and
presentation to users and stakeholders.
Concept Definition
Activities that comprise concept definition are
•
Performance Requirements Analysis — relating to operational
objectives,
•
Functional Analysis and Formulation — allocating functions to
components,
•
Concept Selection — choosing the preferred concept by trade - off
analysis, and
•
Concept Validation — confirming the validity and superiority of the
chosen concept.
Implementing the System Building Blocks
• The objectives of the engineering design phase are to design system
components to performance, cost, and schedule requirements. This phase
also establishes consistent internal and external interfaces.
• Engineering design culminates in materialization of components of a new
system focused on the final design of the system building blocks. Activities
constituting engineering design are:
(i) Requirements Analysis: identifying all interfaces and interactions,
(ii) Functional Analysis and Design: focusing on modular configuration,
(iii) Component Design: designing and prototyping all components, and
(iv) Design Validation: testing and evaluating system components.
Requirements Analysis
• External system interface requirements are especially important at this
point in development.
• User interfaces and environmental interactions require particular attention
Development phasing
• Concept level, which produces a system concept
description (usually described in a concept study);
• System level, which produces a system description in
performance requirement terms; and
• Subsystem/Component level, which produces first a set
of subsystem and component product performance
descriptions, then a set of corresponding detailed
descriptions of the products’ characteristics, essential for
their production
• The systems engineering process is
a top-down comprehensive,
iterative and recursive problemsolving process, applied sequentially
through all stages of development,
that is used to:
(a) Transform needs and
requirements into a set of
system product and process
descriptions (adding value and
more detail with each level of
development),
(b) Generate information for
decision makers, and
(c) Provide input for the next level
of development
Alternative Overview 1
Alternative Overview 2
Alternative Overview 3
• Systems Engineering is a
fundamental process that can be used
to design anything.
• Each step utilizes established design
and analysis tools.
• The process is iterative.
• Between process steps there are
“feedback loops” to review decisions
made in previous steps.
Alternative Overview 4
System Life Cycle Functions
• Life cycle functions are the characteristic actions associated with the system life
cycle.
• They are development, production and construction, deployment (fielding),
operation, support, disposal, training, and verification.
• These activities cover the “cradle to grave” life cycle process and are associated
with major functional groups that provide essential support to the life cycle
process.
• These key life cycle functions are commonly referred to as the eight primary
functions of systems engineering.
5MEC431 System Design
System life cycle- Introduce V-diagram; Overview of SE processes
Systems Engineering Lifecycle Definitions
[1] Development includes the activities required to evolve the
system from customer needs to product or process
solutions.
[2] Manufacturing/Production/Construction includes the
fabrication of engineering test models and “brass boards,”
low rate initial production, full-rate production of systems
and end items, or the construction of large or unique
systems or subsystems.
[3] Deployment (Fielding) includes the activities necessary to
initially deliver, transport, receive, process, assemble,
install, checkout, train, operate, house, store, or field the
system to achieve full operational capabilities
5MEC431 System Design
System life cycle- Introduce V-diagram; Overview of SE processes
[4] Operation is the user function and includes activities necessary
to satisfy defined operational objectives and tasks in peacetime
and wartime environments.
[5] Support includes the activities necessary to provide operations
support, maintenance, logistics, and material management.
[6] Disposal includes the activities necessary to ensure that the
disposal of decommissioned, destroyed, or irreparable system
components meets all applicable regulations and directives.
[7] Training includes the activities necessary to achieve and
maintain the knowledge and skill levels necessary to efficiently
and effectively perform operations and support functions.
[8] Verification includes the activities necessary to evaluate
progress and effectiveness of evolving system products and
processes, and to measure specification compliance.
EXAMPLES:
NASA System’s Development life cycle Accronyms …
SRR – System Requirements Review.
PDR – Preliminary Design Review.
CDR – Critical Design Review.
FRR – Flight Readiness Review.
PFR – Post Flight Review.
Systems Engineering Lifecycle
The V-Model of Systems Engineering
The V-Model of Systems Engineering
• The V-Model, also known as the Verification and Validation Model, is an
engineering framework that emphasizes a systematic approach to ensure highquality products or systems. It is called the "V-Model" due to its distinctive Vshaped diagram, which illustrates the relationship between different engineering
activities. The model highlights the importance of verification and validation
throughout the entire engineering lifecycle. The V-Model consists of two major
branches.
• The left side of the V represents the planning, design, and development phases,
including requirements gathering, system design, detailed design, manufacturing,
and assembly.
• Each of these phases corresponds to a specific verification activity on the right
side of the V. The verification activities include reviews, inspections, testing, and
analysis. This structured approach ensures that each engineering phase is closely
linked to its corresponding verification activity, promoting early defect detection
and reducing the risk of costly rework.
The V-Model of Systems Engineering
• The V-Model offers several strengths that make it a valuable approach for
engineering projects. It promotes early involvement of verification activities,
allowing for better requirements analysis and design validation. By
integrating verification and validation throughout the engineering lifecycle, it
ensures that potential issues are identified and addressed at an early stage,
leading to higher quality products or systems. The V-Model also provides a
clear understanding of project progress by mapping each engineering phase
to its corresponding verification activity. This visibility helps in managing
project timelines and identifying potential bottlenecks.
• Unfortunately, the V-Model also has its weaknesses. It assumes that
requirements are known and stable from the beginning, which is often not
the case in real-world engineering projects. This can lead to challenges when
requirements change or evolve during the development process.
Additionally, the V-Model's emphasis on verification towards the end of the
lifecycle can result in late defect detection and increased rework. In projects
with strict time constraints this can be problematic.
• https://www.linkedin.com/pulse/systems-engineering-tidbits-v-model-erik-puik/