Principles of

Engineering System Design

Dr T Asokan

asok@iitm.ac.in

T Asokan

Principles of

Engineering System Design

Dr T Asokanasok@iitm.ac.in044-2257 4707

Originating Requirements Development: Examples

Air bags, safety device appearing in automobiles in the early 1990’s, became the cause of death for a noticeable number of individuals.

There were severe flaws in the design, testing and deployment requirements envisaged.

Case Study: REQUIREMENT ANALYSIS-Air Bag System Failure in the 90s-

• The requirements defined only a single safety scenario on which to base the design

• No requirement that the airbag remain undeployed during accidents at sufficiently slow speeds that no lives are in danger

• Test condition requirements were wrongly identified.• Pre-impact braking was not taken into account• Injuries due to collision with the airbag was not

considered• Requirements of disposal of unused or partially used

bags were not identified

• Analyse the causes of Apollo 13 disaster as an

engineering system design failure and find out the faults

in the requirements identification that led to the failure.

Self Study

Tutorial

A leading financial company has decided to develop a multipurpose ATM to deliver cash, accept cash, pay bills, and print pass book. For the operational phase of this machine:

(a) Identify at least few operational scenarios and explain them in detail. (b) Develop an input/output trace for two scenarios.(c) Develop an external system diagram (d) Develop a set of originating requirements and prepare the ORD for the operational phase.

Scenario 1. Customer makes deposits

Scenario 2

Scenario 3

Scenario 4

Scenario 5

Emergency situation

Fire

Unauthorised attempt

Breakdown

Theft

maintenance

Operational Concept Scenario

• The system shall give an indication of the status

• The system shall prompt for an identification and

provide opportunity to prove the identity

ORIGINATING REQUIREMENTS

ATM System

XYZ BankCustomer

UnfriendlyCustomer

ATM Admin

ATM Service Providers

Customer Account

DB

XYZNetwork

HW Maint. PQRNetwork

ABCNetwork

Fraud / Break-inTransactionRequest

TransactionRequest

TransactionRequest

TransactionRequest

Response

Response

Response

Response

Log in /Service

Response

Reports

Log in /Request

RetrieveDeposits

DiagnosticResponse

Fill up w/ Cash

Service

DiagnosticResponse

Credit CardCustomer

Response

Log in /Request

BankManagement

Another Bank'sCustomer

Log in /Request

Log in /Request

Response

A leading electronics gadget manufacturer has decided to develop a multipurpose gadget to store/deliver music, store/retrieve data like address, phone number etc., and provide information on location/navigation etc. For the operational phase of this device:

(a) Identify at least 10 operational scenarios and explain them in detail.

(b) Develop an input/output trace for three scenarios and identify I/O requirements.

(c ) Develop the external system diagram (d )Develop a set of originating requirements and prepare

the ORD for the operational phase.(e) Prepare an objective hierarchy for the operational

phase

Group ASSIGNMENT II

Summary• Six functions of system design process• Define system level design problem

– Operational Concept– External Systems– Originating Requirements– Objectives hierarchy– Documentation– Requirement management

• ORD

T Asokan

Principles of

Engineering System Design

Dr T Asokanasok@iitm.ac.in044-2257 4707

SOFTWARE TOOLS FOR SYSTEM ENGINEERING

SysML• SysML is a general purpose modeling language for

systems engineering applications. It is a dialect of UML™, the industry standard for modeling software-intensive systems.

• It supports the specification, analysis, design, verification and validation of a broad range of systems and systems-of-systems. These systems may include hardware, software, information, processes, personnel, and facilities

• The SysML open source specification is publicly available for download, and includes an open source license for distribution and use.

Reproduced with permission from M/s Vitech corporation

Summary

• IT enabled system design procedures increase the efficiency of design process

• Commercial software are available for system design

• CORE, SysML etc. are standard software available for this purpose