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Module 1: Introduction to System Design & Processes

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An Overview of Principles of Engineering System Design

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This is the first lecture on this series oflectures on system design and in this lecture I will introduce the topic and discuss aboutwhat are the contents we are going to discuss in this lecture.System design or engineering system design maybe a totally new topic to some of you orto some of you may be wondering what is system engineering and what are the topics weare going to cover in this lecture. And most of you might have use the system or heardabout system engineering in various contexts. We talk about various systems, we talkabout the democratic system, we talk about education system, we talk about the humanbody as a system and there are many other system we talk about electrolysis systems andthen we talked about even IoT as a system.So, what actually we mean by a system and we discuss these various systems which isaround all of us. A system basically is a set of entities when put together gives a desiredoutput, engineering system is also something similar to that there are various entitiesthere are human beings in the system, there are machines, there are materials, there aremechanisms, there are computer software’s, there are lot of interfaces, hardware, thereare so many entities in the system and when we put together all these entities and putthem in such a way that we get a desired output. So, engineering system is basically acollection of various entities when put together gives you a desired output.So, here also in this course in engineering system design course we are trying to see howdo you actually identify the entities needed for a particular output, how do we put themtogether and how do we actually make sure that this entities put together gives us adesired system.So, the focus of this course is basically to understand the principles on which the systemdesign is focused or system design is based upon and then how do we actually do a systematic way of designing the engineering systems, in order to make sure that itactually produces the desired output. Most of you must be knowing about the variousengineering systems existing in this course we will be focusing on complex engineeringsystems, where actually the magnitude of the number of components the number ofentities or the number of sub system involved is huge therefore, we need to have a verysystematic process of designing the system and that is the focus of this courseengineering system design.Sometimes engineering system design they refer it as a systems engineering and this isvery common to other fields also it is not only to engineering field again see that asystems engineering is applied in various other social sciences also, we talk aboutsystems engineering and the focus this course is basically to look at the engineeringaspects or engineering systems and how do we design the engineering system. You just look at what is system engineering or why do we need systems engineering? Aswe know that most of these engineering systems are there already and we have manynatural systems or manmade systems, but then why do we need to have a very focusedengineering system design approach. If we look at some of the case studies from thehistory we can see that there are lots of failures in the engineering systems and thisactually led to the development of system engineering as I said a discipline. And therefore, we need to have a systematic approach for designing systems, because aa systematic approach will reduce the errors and reduce the failures of the engineeringsystems and ensure that it actually produces the desired output.
Look at the picture in this slide you can see this is an airbag system which most of theautomobiles are having modern automobile vehicles have this kind of airbags as aprotection device for passengers as well as drivers, but when this these devices whereintroduced in year 1990s this actually the safety device itself became a cause of death fora noticeable number of individuals. Though that was not the intention of airbags theintension of the air bags was to protect the people, but because of some design failures orthe system failures this became a cause of death for many individuals because of the mildfunctioning of the airbag.If you look at the reason for it we can see that there were many flaws in the designtesting and deployment conditions and we set it in the system design. So, the one of themain reasons for the failure was flaws in the design testing and deployment conditions.So, that actually tells us that it is necessary to find out the actual requirements of thesystem. And once we have the actual requirements of the system identified we need toensure that these requirements are actually implemented, in the system or the functionsneeded to meet these requirements are implemented and they are tested and verified fully
before we really implement the system for the actual application. So, this was the one of the reasons for the failure of this airbag system. Like this we can see lot of examples Ariane 5 flight 501 failure again this is a case ofsystem failure you can see this Ariane 5 the launch vehicle developed by European spaceagency was first launched.On June 4 1996, with 4 satellites on boards at 37 seconds into flight Ariane 5 veered offcourse and disintegrated shortly. Thereafter, again this is a failure from the historyengineering failure of the system as you know this is a very complex system all thelaunch vehicles are basically very complex engineering systems and again this had someflaws in the interfaces that design interfaces were not proper. So, there were some flawsin the conversion of the data and this actually led to the failure of the engineer thisparticular system.So, a major flow in the communication interface resulted into this catastrophe. So, againit actually emphasize the importance of having a systematic approach in the design anddevelopment of engineering system, because there are many subsystems and there aremultiple interfaces and these interfaces are not properly designed in that may result into atragedy like this. This is a another example which is very famous and most of you may be aware of it theColumbia disaster again space shuttle Columbia when it was returning back to the earthafter it is mission and disintegrated into pieces and all the astronauts were killed in thisparticular incident.This actually happened in 2003 February 1, 2003.
In fact, these are the crew members we actually died during the return of the spaceshuttle and as you know one of India’s daughter is also lost her life in this particularmission. If you look at the details of this particular incident we can see that this particularincident happened because there was a small problem in the space shuttle took off one ofthe tiles on it is surface developed some cracks and it was a an issue which actuallymission managers they identified in the beginning itself when it took off they could seethat.There is a problem with the one of the tiles on the surface, but then it was not possible tobring it back immediately. So, they did lot of analysis they did modelling analysis and lotof simulations to see what are consequences are for this particular damage. And finally,after lot of analysis and a lot of studies and then they took a decision that this may notcause a major problem. So, that they can continue with the mission and then returned thespace shuttle back to earth and then do the repair work. So, the here actually it was adecision making under uncertain conditions.So, it was not sure I mean the team was not very sure whether the system will perform asper the simulation, but they need to take a decision under lot of other uncertainconditions and they took the decision to continue with the flight and then while comingback, while the shuttle was returning back the temperature grows up very high and then
it actually to certain to the complete failure of the system. So, whole space shuttle and allthe crew were killed in the accident.So, here you can see that it is not only the engineering aspect, but there are. So, manyother aspects like making a particular decision about whether to continue with the systemmission or not. So, we need to consider. So, many other aspects of the system and thensee then take a decision under lot of uncertainties. So, taking a decision under veryuncertain conditions also is part of system engineering. So, here all this incidencesbasically tells us that engineering complex system is very difficult and there are lot ofissues need to be taken into account when we actually design and develop anddeployment deploy an engineering system.
To show the level of complexities you can take this example for ICBM project which isthe intercontinental ballistic missile project Atlas, the Atlas had lot of various stepsinvolved in this development of this particular missile shield system.So, SM-65 was the missile designed by the air force ballistic missile division and builtby a conveyer division of general dynamics, this was originally designed as an ICBM inthe late 1950’s and the atlas was the foundation for a family of successful space launchvehicle now build by united launch alliance, the atlas rocket family is today used as alaunch platform for commercial and military satellites and the others space vehicles.
So, this actually got a series of a launch vehicles the present one is it was built around2002 to 2003, but the development started somewhere in 1950’s and then actually therewere the various versions of this particular program a missile. To see the complexity ofthis development you can see that there were 1800 scientists and engineers working inthis particular project there were 17 contractors there were 200 sub-contractors and200,000 suppliers involved in this particular project. So, you can actually imagine on thescale of the project with the 18, 000 scientists and 20,000 suppliers and in between lot ofcontractors and subcontractors working together in order to deliver a particular project.So, the management of the whole man power the subsystems at the interfaces all thisbecomes too complex for anyone to manage the system.This actually shows the evolution of atlas family you can see that started somewhere in92 it is a first version of this atlas 2a and then atlas 5 is the latest one it is atlas 5 familyconsists of this the 3 series, then it was final one was developed in 2002. You can see thatas the development progress there will be a lot of additions lot of changes in this system,and every time we somebody has to closely monitored the variations in that systemdesign and closely record it and then maintain a proper strategy for the development also.So, all this makes the system development very complex and requires a very systematicapproach in the design development as well as deployment and even the disposal of thesystem.
So, let us see the what are the important points we need to discuss or we need to learnwhen we design this kind of a complex engineering systems, to define the systemengineering basically it is a top down lifecycle approach to the design, development, anddeployment of large scale systems, processes, or operations to meet the effective needsof users and stakeholders in a cost effective high quality way.So, as you can see it is a top down life cycle approach. So, it is not only the design whichis important. So, we need to look at the whole life cycle of the system, where we look atthe design, the development, the deployment, and even the training and maintenance ofthe system and then how do we actually dispose the whole system. So, it actually a lifecycle approaches.Where we need to look at all aspects of the life cycle of the system and then every lifecycle need to be analyzed and we need to make proper design for this life cycles and wedesign a system we need to look at how do we actually. Finally, dispose the system is itgoing to affect the other existing systems or natural systems or we can be use it for someother system or can upgrade the system further. So, on these aspects need to be taken intoaccount when we actually go for the design of this type of a complex engineeringsystem.So, system engineering basically an organized and systematic way of design and then itconsiders all the factors involved in the design. So, it is not only a particular aspect of the
system. So, a we need to look at the all the aspects of the design. So, looking from thecustomer requirements to the disposal of the system everything need to be designed thatis all the factors need to be considered and then it integrates all the disciplines andspecialty groups into a team effort.So, here actually you will have multiple disciplines. So, it is not only a particulardiscipline engineering that would be multiple specialty groups and this actually tries tointegrate them into a team effort. And it ensures the business and customer needs or allstakeholders and ensures as systems that needs the user needs. So, here actually thebusiness needs as well as the customer needs of all stakeholders there are multiplestakeholders in the system development. So, we need to ensure that we take care of theother stakeholder’s interest and meet their needs of these stakeholders.(Refer Slide Time: 14:36)
So, what are the things what we are going to discuss in this particular lecture. So, we willsee the topics to be covered in this particular course we have around 30 to 40 lectures onsystems engineering or principles of engineering system design. So, the main topics to becovered in these lectures are first basically the introduction to system engineering andthen we discuss about the system engineering design process.So, what are the different life cycles in a system and what are the different productdevelopment processes we can employee and then we go through the 6 functions ofdesign process, basically we will define the system level design problem then functional
architecture of the system, then physical architecture, basically the functionalarchitecture. We will look at the functions needed in the system, in order to satisfy thecustomer requirements which are identified in the system level design problem and thenwe go to the physical architecture, where the physical architecture will try to convert thefunctions into physical building blocks. And then we develop that an operationarchitecture, which actually integrates all the physical architecture, then we develop theinterface architecture basically to look at the subsystems and the interfaces needed forthese subsystem. And finally, we will do the integration and qualification. So, that is thelast function in the design process.Whatever we design we to do an integration of or the sub systems and then ensure thatthe systems or the subsystem meet the requirement of the stakeholder so that is thequalification process, where we do the testing and analysis of the whole system andensure that it actually meets the customer requirements and ones which is verified thenonly it will be used for customer application or for the further development of thesystem.So, this are the 6 functions of the design process our main focus will be on these 6functions we will try to understand how do we actually carry out these functions in thedesign process across the life cycle and then we go to the other topics such as.(Refer Slide Time: 16:42)
A system failure analysis so we will look at the failure analysis of the system and thensee how do we actually design a system in order to make sure that the possibility offailure is very minimal, we discuss about the decision making under uncertainty wherewe look at the various options available or various techniques available in order to take adecision based on the available information at that time.So, there is a risk involved in decision making. So, we will see how we actually reducethe risk involved in the decision making process and then we will discuss about fewsystem modeling tools because we have to do lot of analysis I will be design theengineering system. So, will discuss about few tools available for modeling of the systemand similarly we will look at the statistical tools for engineering design basically thedesign of experiments and design for reliability etcetera. There are few software toolsavailable for system design.So, I will briefly explain about these tools and how do we use these softwares foreffective design of engineering systems and of course, we will take few case studies andexamples to show how to use these tools as well as these methods in the design ofsystem, as well as the implementation of the system. And then to see how the principlesof a systematic process actually helps us to design complex systems and ensure that itactually meets the customer requirements. So, this are the main topics which will becovered during this lectures may be 30 to 40 lectures will be there which actually willcover all these topics and few case studies also.
Some of the references for this lecture the text book is Dennis Beude the engineeringdesign of systems, then another book by Alexander Kosiaff and William N Sweet,Systems Engineering: Principles and practice, then Saeed Niku Creative Design onProducts and Systems, Wiley 2009 edition. Apart from these I will giving you fewassignments and group projects the assignments will be uploaded to the web and you canactually try it yourself some of the answers for this assignments is also will be given inthe web itself, you can actually refer to that and then see whether you are actually goingit properly or you are actually understanding the principles and then how to apply theseprinciples for the design of complex systems.There will be few group projects also of course, this group projects you can actually ifyou are in a group or 3 or 4 students together you can work out these projects and thentry to see how to implement or how to use the principles in a real life scenario or realcase studies; so that has. So, you can try as part of the course. So, the main courseobjectives what we actually can see from after at the end of this course we have someobjectives in providing these course materials to you.
(Refer Slide Time: 19:48)
So, the end of this course you should be able to develop a systems engineering plan for aproject and judge the applicability of any propose process strategy for methodology forsystems engineering. So, you should be able to plan a project in terms of systemsengineering and then judge the applicability of any propose process for this particularproject and apply the most essential systems engineering tools to realistic problems.So, if you have a realistic problem how do we actually apply the most essential systems.So, that also you should be able to understand by the end of this course and thenrecognize the value and limitations of modeling and simulation. We have will bediscussing about many simulation and modeling techniques. So, you will be able torecognize the value and limitations of these models and formulate an effective plan forgathering and using data and how do we actually gather data and use them in the design.And then determine the effects of manufacture, maintenance and disposal on systemcourse and value. So, you should be able to determine the effects of cost on variousaspect like manufacture maintenance and disposal on system. So, they are all differentvarious cost involved in this.So, you should be able to understand the impact of this on system design. So, these arethe course objectives. So, what we mentioned. So, far is the introduction and then whatare the topics to be covered in this course and what are course objectives. And now willgo to discuss more about the systems engineering and we will try to define the systems
engineering from the design point of view from the over from the engineeringperspective we will design what is system, what is engineering, and what is systemengineering and what are the roles of system engineers in developing this kind ofcomplex systems.So, let us look at what is the definition for engineering because systems engineering isbasically I can say that there is a system and there is engineering. So, we will discusswhat is engineering and what is system and then what is this system engineering, thereare lot of definitions for engineering, but basically if you look at engineering is a processof doing things in a effective way.Even without engineering or without a proper definition for engineering engineeringprojects were taking place people were doing it because whenever you try to dosomething in a cost effective and efficient manner then we call it as a engineering, asArthur Wellington said once engineering is art of doing something well with one dollarwhich anyone can do with 2 dollars. So, basically we are trying to do how do we do it inan efficient way with using the non-principles and practices how do we a complete a
project in a cost effective and in a efficient way that is basically the engineering.(Refer Slide Time: 22:39)
But there are different definitions. So, as far the accreditation board for engineering andtechnology engineering is the process of device in a system component or process tomeet desired needs. So, basically it is a process of devising a system component or
process to meet the desired need it is a decision making process often iterative in whichthe basic sciences mathematics and engineering sciences are applied to convert resourcesoptimally to meet a stated objective. So, here an optimal utilization of the resources tomeet a stated objective is defined as engineering.(Refer Slide Time: 23:14)
Then what is a system. So, we discussed about system or we briefly mentioned aboutsystem basically there are various systems doing in the nature there are manmadesystems artificial systems are there. So, how do we actually define a system there arevarious definition for system a system is defined as a group of interacting inter related orinter depended elements forming a complex whole.So, that is one of the definitions the other one is a functionally related group of elementslike the human body regarded as the functional physiological units or an organism as awhole especially with regard to it is vital processes or with functions, the other definitionis a group of physiologically or anatomically complementary organs or parts like thenervous system or the skeletal system. So, this are actually a physiologically oranatomically complementary systems a group of interacting mechanical or electricalcomponents or a network of related computer software hardware and data transmissiondevices.So, if you took an internet as a system again it is a network of related computer softwarehardware and data transmission devices.
(Refer Slide Time: 24:24)
So, like this there are multiple definitions, standard definition is basically a system iscommonly defined to be a collection of hardware, software, people, facilities, andprocedure organized to accomplish some common objectives. So, that is a commondefinition for engineering system which is a collection of hardware software people andother facilities in order to get to accomplish common objectives.
NASA System Engineering Handbook the definition for a system is given as a set ofinter related components which interact with one another in an organized fashion to add a
common purpose. So, that was a definition given by the NASA systems engineeringhandbook.For an engineering system and it actually contains many components. So, there can bevery diverse components in the engineering system can be persons or organization, therecan be software data that can be equipment and hardware facilities and materials andservices and techniques. So, you can see they are quite diverse persons and organizationssoftware data equipment or hardware in facilities and material services and techniques.So, this can be any system can have any of these components some of the maybe have allthese company. So, some of them having a few of these components but any system willbe having very diverse components in order to meet the requirements.(Refer Slide Time: 25:42)
As per the NASA system engineering handbook, system engineering is a robust approachto the design creation and operation of system. So, it is not only the a design activity it isbasically an approach to the design creation and operation of systems and it consists ofidentification and quantification of system goals. So, this are the approach for the systemdesign we need to look into this aspect like the identification on and quantification ofsystem goals, creation of alternative system design concepts, performance of designtrades that is there may be many design trade off in the system, because when we designa system we will be looking at the aspects of trade offs were we need to reduce the cost
sometimes or increase the performance or when you try to increase the performance thecost may go up.So, we need to have some kind of a tradeoff and that kind of trade off studies are alsopart of the system engineering. So, that is the design trades then we have the selectionand implementation of the best design that is the balance and robust design then we haveverification that the design is actually built and properly integrated in accordance withthe specifications then assessment of how well the system meets the goals. So, this arethe important steps involved in the system engineering or design of engineering systems.So, we look at the system goals then the design concepts then trade off then theverification strategies and then assessment of how well the system performed to meet thestakeholder needs, these are the things important in the design of systems.(Refer Slide Time: 27:15)
So, that is about the system and then we discussed about engineering also then what issystems engineering? So, we have the system which is a collection of entities whichactually provides you a particular output and then and systems engineering which againwe briefly saw this in the earlier slides, system engineering is a top down life cycleapproach to the design development and deployment of large scale systems processes oroperations to meet the effective needs of users and stakeholders in a cost effective high
quality way.
So, it actually involves an interdisciplinary approach and means to enable the realizationof successful systems. So, again there are multiple displays involved in this that is why itis an interdisciplinary approach and the means to enable the realization of successfulsystem. It focuses on defining customer needs and required functionality early in thedevelopment cycle, documenting requirements then proceeding with design synthesisand system validation while considering the complete problem. That is the mostimportant aspect of system design it focus on a defining customer needs and very earlystage.So, even before we really start the design process we look we looks at the customerrequirements in the very early stage and then document these requirements and try toidentify the origin of these requirements look at the grass root level requirement and thentry to design for the problem and documents is requirement in a proper way a systematic