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Module 1: Introduction to System Design & Processes

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Engineering Systems Classification

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So, today we will discuss little bit more about system engineering some of the basicprinciples before we really get into the actual design of engineering systems.(Refer Slide Time: 00:54)
So, this lecture is divided into two parts in the first part and I will be talking about theclassification of a systems basically the natural systems and artificial or manmadesystems and we will talk about the engineering system examples, when do we need reallyto use system engineering and what are the system dimensions basically what kind ofsocial and technical dimensions are there for the engineering systems. And then we willtalk about the system design hierarchy and then the role of system engineers, how systemengineers play a vital role in design development and execution of engineering systems.
(Refer Slide Time: 01:28)
So, let just look at the classification of systems as we explained in the last class we foundthat the there are various kinds of system there are a manmade systems and there arenatural systems. So, we can basically divide these systems into two classes, one is thenatural systems and the other one is the artificial systems.As you know naturally systems is the existing in the nature. So, human body is a systemecosystem is there then we have the systems of planets and other celestial bodies. So,these are the natural systems and there are complex natural system which is a humanbody is an assembled where the complexity of the system is still not understood fully. So,that those are the examples for a natural system where some of them are very simple, butsome of them are very very complex which is beyond our analysis at this stage. Then wehave the artificial systems which are basically man made. So, in manmade system wecan classify them into many classes depending on the complexity and humaninvolvement.As you can see in this picture there are artificial systems with the complex behavior, butvery simple structure and we have artificial system with complex behavior and structure.So, there may be complex behaviour as well as the complex structure for the artificialsystems. But then we have systems with the human intervention or human behavior likeartificial complex system with the complex technical, but the simpler human structurethen we have artificial complex systems with complex human, but simpler technical
structure and artificial system with technical and human structural complexity. So, thereare depending on the system type we can actually find whether this and actually classifythem whether they are complex in human behaviour or complex in technology or thetechnical behavior.For example, if you take operation of a missile system it is more of a human complexhuman behaviour and when you take the design of a missile system it is more of complextechnical behaviour. So, depending on the context in which we use the systemengineering we can actually divide them into human behavior, system with the complexhuman behaviour or complex technical behaviour. So, manmade natural system orcomponents also may include in this systems because there maybe some naturalsubsystem which is part of the manmade systems. This is the basic classification of thesystems.(Refer Slide Time: 03:51)
Let us just take few examples for these systems and then try to understand what are thesubsystems involved and how they have become part of a larger system or a subsystemor some other system. Take them for example, spacecraft as a system as all of you knowit can be considered as a system composed of a variety of subsystems so every spacecrafthas got many subsystems and this spacecraft architecture it is well defined because ifthere is a well defined structure for the aircraft architecture and the subsystem are in turncomposed of very smaller subsystems.
For example, you take the communication subsystem or the payload subsystem of aspacecraft as you can see communication is payload in a space craft and we can considerthis as a subsystem of the spacecraft. So, you can see here there are many other systempart of the a payload, you can see that antenna is a part of the communication payload,amplification, modulation, demodulation, routing and encryption, decryption, filtersmultiplexers these are all becomes part of the subsystem of the spacecraft.Similarly, you have the spacecraft where attitude determination and control is there,command and data handling is the payload processing is there, then power, propulsion,software, structures, telemetry, thermal systems. So, these are all becomes part of themain system. So, if you take spacecraft as a system then you can find these are as thesubsystem of the spacecraft.(Refer Slide Time: 05:21)
But if you take the space system as a whole system then you will find that the spacecraftis a part of a largest system which is the space system. We will have many spacecraft inthe space system which is the other spacecraft in the constellation, then you havedifferent segments for the space system like you have the ground segment, then you havethe space segment, then you have the launch segment. So, this all becomes a subsystemmain system of the space system.Though spacecraft can be considered as a system by itself when we define the spacesystem then the spacecraft becomes a subsystem of the main space system. Thus any
system can be considered as a subsystem of a larger system or can be considered as asystem by its own merits. So, it depends on how you actually define the system and whatactually are going to design. So, depending on that we need to define what is thatparticular system and what are the subsystems of the main system and then how do youdefine the boundary of the system and the subsystems. As you can see here these are thethis actually shows the space system where there is a launch segment, there is a spacesegment and there is a ground segment which are all part of the main space system.(Refer Slide Time: 06:34)
This figure again shows another diagram which actually shows the product developmentsystem for ford motor company. We will not go into the details of this figure as we willbe discussing it in the later stage when we discuss about the product developmentprocess or the system development process, we will discuss about in detail. But it showsthat how from the initial customer requirements the customer satisfaction is achievedthrough various processes and how it passes through different stages of designfabrication, testing, integration and then validation and then to reach the customer.So, this again the development it becomes a part of a major system or the productdevelopment system. We will discuss this detail at a later stage.
(Refer Slide Time: 07:22)
This is another example for the system complex system manmade system which is the airdefence system. As you can see that air defence system as got various subsystemssomething can be in the air or something can be on the ground and something can becompletely controlled by the man or completely automated with the different sensors andsignal processors kept at different locations.As you can see they are radar sites which actually used to find out the locations of theaircrafts then there are early warning, and control systems which actually consists ofmany aircraft and other sensor suits. Then we have the traffic control air traffic controlcentre which actually controls the movement of air traffic then you have this interceptorbases where the air defence systems are placed from where they actually take off andthen carry out the missions.Then there are civil defense applications for this particular system. So, civil defensesenders will be sending information to the main database center or the control centre thenwe have the animation systems with various location, there are radio sites fortransmission of signals. And then we have all those base centers which actuallycoordinates them in activities of various centers in pass part of this system.So, to as you can see it is a fairly complex system with the various subsystems and lot ofinteraction between these systems and therefore, the system engineering concept is wellsuited for this kind of a complex man made system.
(Refer Slide Time: 08:49)
This one we discussed in the previous class about atlas project as you can see there were18,000 scientists and 17 contractors with 200 subcontractors and 200,000 suppliers andthe whole process coordinated by Ramo Woodridge Corporation.So, again you can see that there were 200,000 supplier. So, you can see the complexity ofhuman involvement in this particular project apart from the technical complexity ofdesigning the missile there were it is actually a larger complex human behaviourinvolved in this system and therefore, we need to look at the human interaction andhuman behaviour aspects in the design of systems.
(Refer Slide Time: 09:30)
These are the key aspects of the atlas project. So, this actually was the one of the projectwhich firmly established the systems engineering approach to management. It identifiedthe key challenge early in the system that are what are the key challenges in itsreentering the atmosphere what are the challenges, so all those things were analyzedinitially itself and then the system design process are preceded. As you can see here thisfigure shows the interaction between various entities in this particular project as you cansee there is air force one agency which is most of the customer in this case and the RWcorporation is the agency which actually coordinated the whole design process.Frequently there were a lot of interaction between the customer and the contractor atdifferent stages and this military considerations and a contractual control were actuallycoordinated by the RW corporation with what are the requirements of army and how dothey actually include those requirements into the system design.And then there were many other subsystems like propulsion system, guidance systemand control system and then there were many sub contractors which are designingdeveloping and supplying some of the components and the systems for this. So, you cansee there is a very good hierarchy of information flow as well as the assignment of taskand responsibilities and this actually calls for the principles of system engineering andthat is why this was one of the project which firmly established the principles of systemengineering approach to management of a large scale engineering systems.
(Refer Slide Time: 11:11)
So, that there are different kinds of a systems and there are different kinds ofcomplexities in the system. But then we need to find out when do you need to reallyapply the system engineering concepts where are the projects are good candidates for asystem engineering or there are projects which does not warrant the need for a systemengineering concept. So, how do we decide this based on our approach to the project orbased on understanding of the project?We discussed about some of the failures in the previous class system engineering failuresin the previous class where actually we discussed about the air bag system failure forpassenger cars and we have found that there was a failure in the requirement analysis ofthe project. There was a failure in pathfinder which is again a space system where thecommunication failed in the pathfinder this was because of the interface design failureand then Ariane 5 launched vehicle failure we discussed these are all various example forsystem failure and whether there are the candidates for the application of engineeringsystem design. If you look at we need to find out the real causes of system failures to seewhat actually really happened in the system or what actually caused the failure of thesystem.Now, this discussion point for you can actually find out from the literature or throughdiscussion with your friends or your colleagues what actually happened in our GSLVfailure. So, we know that our geo synchronous launch vehicle have failed recently and
there were many icons for the failure of the system. So, probably you can identify thatthere was a system failure or it was a component failure.So, probably we will be able to distinguish between these two what actually happenedwhether it is a there was a failure in the whole system or the process of a development ofa system or there was a component failure which actually more of a an engineeringfailure which actually the fail to meet the desired design requirements of the thatparticular component. When you analyze these kind of these kind of a failures then wewill know that whether it was a problem with the technical design of the system or it wasa problem with the whole system design.So, based on that we will be able to tell, oh this was a failure in the system engineeringand therefore, we need to look at the process and procedures we followed for engineeringthe system and accordingly we need to go ahead with the design of the system or applythe principles of a system design.(Refer Slide Time: 13:54)
So, let us just look at what are the criteria went for when we decide to take the systemengineering principal for a particular project. The characteristics of a system whosedevelopment test and the application required the practice of system engineering that thesystem is an engineered product and hence that specifies a specified need. So, that is oneof the basic requirement it is an engineered product and hence satisfies a specific needmost of the systems actually satisfy this requirement.
The system consists of diverse components that integrates relationships with one anotherand hence it is multidisciplinary and relatively complex. This is one of the importantaspect we need to look at what are the different components and different systems orsubsystems which comes as part of this one, what are the discipline or the technologydomains we need to have to achieve the target or the achieve the function of the system.So, once we know that there are people who domain expertise requirement and multipletechnology requirements and there are lot of interaction between these different domainsthen it will be a very good candidate for system engineering because multi system ormulti domain interactions cannot be normally captured in the normal design process andtherefore, we need to try to incorporate these factors into the design or we have to take into the count these factors when we consider the system design and then we need to makesure that we apply the system design principles to such designs.Then another factory that the system uses advanced technologies that are central to theperformance of its primary functions and there are advanced technologies which are notwell proven at this stage or it is still in the development stage the advanced technologiesthen probably that it is a very good case for system development because systemdevelopment actually system development principle basically takes care of the modelingsimulation verification and validation of different technologies before we are reallyimplement those technologies into the system.So, if any system which actually satisfies these three conditions, but the system is anengineered product and have a particular specified need and it actually warrants the useof multiple disciplines as well as technologies and there are newer or advancedtechnologies which are being used in many system then such systems are a goodcandidate for application of engineering system principles. Some of the examples forsuch systems are the satellites man made satellites aircraft auto assembly plant railwayreservation system. So, these are all some of the system or an engineering systemmanmade systems where we can really use the principles of a engineering system designto achieve the desired goals from the system. Because they are all satisfy theseconditions their multi domain expertise needed there were lot of interactions betweendifferent domains and different subsystems and there are advanced technologies used.So, for example, if you take the railway reservation system which is one of the bestonline systems we have for rebooking of a railway tickets you know that there are
multiple subsystem, there are customers, there are booking agents, there are railwaystation booking facilities, there are centralized servers and there are payment agencies.All these are interacting with the main system and they are using the latest technologiesof communication and networking as well as data analysis and data processing.So, that becomes a very good candidate for applying the principles of system engineeringwhen we developed systems like this systems of complexity like this.(Refer Slide Time: 17:37)
So, in the previous class the system engineering which actually integrates all thedisciplines and speciality groups forming into a team effort forming a structuredevelopment process that proceeds from concept to production to operation. So, if youapply these principles of a system engineering we can actually have a structured designprocess its actually we will start with the development process and proceeds fromconcept to production to operation of the system. And it considers both the business andthe technical needs of all customers with the goal of providing a quality product thatmeets the user needs.So this is again a discussion point for you we discussed about the system engineering indetail, so what actually system engineering in when do we in order to use the systemengineering principles what are the basic requirement of applying system engineering.So, probably you can have a discussion what distinguishes system engineering from thenormal or the conventional engineering, what are the factors which actually distinguishes
from a system engineer, how a system engineer is different from a conventional engineeror a domain expert. So, this will actually help you to understand the system engineeringconcept in a better way and appreciate the importance of system engineering indeveloping complex engineering systems.(Refer Slide Time: 19:01)
We discussed about the system and then as I mentioned this system has got a technicalcomponent as well as a human component because there are complex human systemsand complex technical systems.So, let us just look at what are the technical dimensions of the system as you can seethere are 6 levels of technical dimension for any engineering system. So, you will startfrom the highest level it is basically the physical environment of the world were actuallythe system operates. So, we call it as the system context. So, every system will beoperating in a particular environment so that environment becomes the dimensions of thesystem because all these dimensions are important in system development because allthese dimensions have impact on the system or the system can be impacted by thosefactors.So, if you look at the highest one then it can be a physical environment of the world andthen we can have different levels if I start from the lowest level at that is zero thatbecomes the parts or lines of code of a system. So, you will be having many smallcomponents which are of the cell for which does not require any specific design, like you
have nuts bolts and other kinds of screws and small fascinates becomes parts or a smallparts or the zeroth dimension of an engineering system. So, if you take the software thenthe lines or code becomes the zeroth dimension of this technical dimension.The next level is the components or majors software units. So, if you have maincomponents of the system that becomes the first level dimension or the major softwareunits in the case of software. The third level is the major subsystems or sub assemblies.So, you will be having subsystems or sub assemblies in a system that becomes the thirdlevel of system, but in the case of a software then the software becomes the next levelwhere you have subgroups or the sub particular group a software which actually carryout a specific task.Then the next level is the larger system which is an aircraft if you take the space systemor air transportation as a main systems then aircraft becomes the next level of componentor next level dimension here or anywhere system related to that. Then the higher level isthe air transportation system or the air defence system. So, if you consider that as awhole system then air transportation or air defence becomes a major system and thehighest level is the as I mentioned it is the physical environment or the world in which itoperates. So, these are the 6 technical dimensions of an engineering system and all thesetechnical dimension has got impact on the system developments. So, every system can bein begged by these dimensions and therefore, we need to make sure that we take intoaccount all these parameters into consideration when we design our system. So, that isabout the technical dimensions.Let us look at the social dimensions. So, every system has got because it is some socialimpact where as the human is involved and it is mainly designed for human use andtherefore, there is a human intervention or human impact on the system and that is whywe have a social dimension for the system. Again we can have 6 levels of socialdimensions, so the highest level again it is a society nations or communities where thesystem is being used. So, depending on the country or depending for the society where itis being implemented we can say that it becomes the highest level of a social dimensionfor the engineering system.Then the lowest level is of course, the individuals who actually directly interact into thesystem or directly involved in the recent development used or maintenance whatever
way he interacts with the system that becomes the zeroth dimension of the engineeringsystem. Then there are working groups or teams either development teams or theoperation teams or maintenance team they are becomes the next level of socialdimension. Then the organization units where the particular organization where they aredeveloping they will be design team there will be a fabrication team, there will bemachine maintenance team. So, there becomes a third level of dimension which is theorganizational units.Then single organization or the next level where the larger organization like drdobecomes a single organization with many labs across the country. So, each lab becomes asingle organization which is the fourth dimension level dimension. Then there areextended multi organization enterprises including partners and suppliers. So, this actuallyis a group of supplies consumers and subcontractors they are become the fifth level ofextended multi organization. So, if a company is developing a particular system thenthere are many suppliers quality assurance teams there are organization which monitorthe quality of the system, there are organization which actually is going to finally, use itthey are also part of the system. So, like that there are extended multi organizationswhich actually becomes part of the fifth level of social dimension and the last one is thesociety as I mentioned where actually we are going to use the system that becomes thefifth level of the society as a social dimension.So, as you can see there are technical and social dimensions for an engineering systemand therefore, we need to look into the aspect of the social aspect as well as the technicalaspect of the system design when we start the design and development of an engineeringsystem which is finally, going to be used by the customers where
there are a lot of humaninteraction as well as there are technical complexities.
(Refer Slide Time: 24:42)
So, we discussed about the different dimensions of the system and I told you that thereare different technical dimensions for the system. So, you can see that as I mentionedthere are lower level parts or components which actually becomes the zeroth levelsystem dimension. Then there are sub components were actually the signal amplifiercathode ray tubes or gear trains or walls or nozzles becomes the sub components.Then we have the components like a signal receivers data displays power transfermaterial, reactors, thrust, generators and etcetera, then we have the subsystems where assignal networks database material preparation engines etcetera are being used fordeveloping the final system and you can say these are the communication system can bea system on its own merits. And then there are information systems material processingsystem aerospace systems. So, these are all the a top level and of course, when you usethese systems for another system then these becomes sub systems of the another majorsystem like air diffence system if you take as a system then this communicationinformation which will processing all these becomes the subsystem of the main system.So, that was about the system in general.
(Refer Slide Time: 25:55)
Then we need to see who are the people who design it and what they actually they do.So, these people who are actually responsible for a design development and integrationand verification validation of a engineering systems are known as system engineers, theyare different from the engineers or the domain experts like mechanical engineer orelectrical engineer or an electronics engineer system engineers are not the exactly thedomain experts, but they are more like a people who actually see the big pictures and tryto integrate many things into a single piece. So, they will be having the larger picture ofthe system and they know what can go wrong what are the issues coming up.So, they will actually do the troubleshooting and then make sure that the systemdevelopment process goes takes place in a structured manner without any problems. So,the system engineers are those who design the overall architecture, but they are not thepeople who really design the components the component design is basically done by thedomain experts or the engineers or mechanical engineers or electrical engineers. Theyprioritize the system requirements, there are different requirements for the system thosewho are designing the component may not be knowing what are the actual requirementsof the original system which the component is a part.So, the system engineers are the people who actually prioritize the system requirements.