The document discusses developing well-formed engineering requirements. It outlines that by the end of the chapter, the reader should understand properties of engineering requirements like being abstract, verifiable, unambiguous and traceable. It also discusses developing a complete requirements specification by identifying requirements from customers, environment and technical standards. Advanced analysis methods like tradeoff analysis are examined to refine requirements.

1. Revised by S.P. Chew (2009)

2. By the end of this chapter, you should:
 Understand the properties of an engineering
requirement and know how to develop well-formed
requirements that meet the properties.
 Be familiar with engineering requirements that are
commonly specified in electrical and computer systems.
 Understand the properties of the complete
requirements specification, as well as knowing the steps
to develop one.
 Be able to conduct advanced requirements analysis to
identify tradeoffs.
2

3. Raw (Marketing) Requirement
Customer
Customer Feedback
Customer Representation Develop Technical Feedback
System
Requirements
Constraints & Technical
Standards Representation Technical
Environment
Community
3

4. Properties:
1) Abstract
• Specify what system will do, but not how it
will be implemented.
2) Verifiable
• Should be a way to measure or
demonstrate that the requirement is met in
the final system realization
4

5. 3) Unambiguous
◦ Each requirement should have a single
unambiguous meaning
◦ Stated with short complete sentences
4) Traceable
◦ Valid in marketing requirements.
5

6. Does the following requirement meet the four
desirable properties? (abstract, verifiable,
unambiguous, traceable)
“The robot must have an average forward
speed of 0.5 feet/sec, a top speed of at least
one foot/sec, and the ability to accelerate
from standstill to the average speed in under
one second.”
6

7.  IMPORTANT – Your requirements for
your project must also be REALISTIC.
 => You need to demonstrate that the
target you have selected is technically
feasible.
 How are you going to do this?
7

8.  Constraint = design decision imposed by the
environment or a stakeholder that impacts or
limits the design.
 Example contraint: The system must use a
PIC18F52 microcontroller to implement
processing functions.
8

9.  A standard is established way of doing things
that ensure interoperability.
 Question is, what standards are relevant to
your project and how do you use them?
 Different levels of usage
◦ User
◦ Implementation
◦ Developer
 Types:
safety, testing, reliability, communication, dat
a, documentation, design, metastandards and
etc…
9

10.  Structured workshops and brainstorming
 Interviews and surveys
 Observation of processes and devices in use
 Benchmarking and market analysis
 Prototyping and simulation
 Research survey
10

11.  Need to know what type of requirement to
select for a given system.
 These are but EXAMPLES – you must
determine the correct ones for your system!
 Hint: don’t just try to copy and paste them.
11

12. Performance
 The system should detect 90% of all human
faces in an image.
 The amplifier will have a total harmonic
distortion less than 1%.
Reliability & Availability
 The system will have a reliability of 95% in
five years.
 The system will be operational from 4AM to
10PM, 365 days a year.
12

13. Energy
 The system will operate for a minimum of
three hours without needing
Environmental
 The system should be able to operate in the
temperature range of 0°C to 75°C.
 The system must be waterproof and operate
while submersed in water.
 to be recharged.
Many more examples in the book.
13

14. Steps to follow to develop the requirements
specification:
◦ Identify requirements from the customer,
environment and technical community
◦ Ensure the engineering requirements are well
formed
◦ Organize the requirements. Similar requirements
should be presented together and relationship
btwn. Engineering and marketing requirements
identified.
◦ Validate the requirements specification.
14

15.  Normalized/Orthogonal
◦ Should no overlap or redundancy between
engineering requirements.
 Complete Set
◦ Addresses all the needs of the end user and also
those need required for system implementation.
15

16.  Consistent
◦ Should not be self-contradictory
 Bounded
◦ Determining the min acceptable bound for target
values
 Modifiable
16

17.  Ask the customer if the requirements meet
their needs.
 Usually done in teams.
 For each engineering requirement
◦ Traceable?
◦ Verifiable?
◦ Realistic & technical feasible?
 For the complete Requirements Specification
◦ Orthogonal?
◦ Complete?
◦ Consistent?
17

18. Marketing
Requirements Engineering Requirements Justification
1, 2, 4 1. The total harmonic Based upon competitive
distortion should be <0.1%. benchmarking and existing
amplifier technology. Class A, B,
and AB amplifiers are able to obtain
this level of THD.
1–4 1. Should be able to sustain This power range provides more
an output power that than adequate sound throughout
averages 35 watts with a the automobile compartment. It is a
peak value of 70 watts. sustainable output power for
projected amplifier complexity.
2, 4 1. Should have an efficiency Achievable with several different
( ) >40 %. classes of power amplifiers.
3 1. Average installation time for Past trials using standard audio and
the power and audio power jacks demonstrate that this is
connections should not a reasonable installation time.
exceed 5 minutes.
18

19. 1–4 1. The dimensions should Fits under a typical car seat.
not exceed 6” x 8”x 3”. Prior models and estimates
show that all components
should fit within this package
size.
1–4 1. Production cost should not This is based upon competitive
exceed $100. market analysis and previous
system designs.
Marketing Requirements
1.The system should have excellent sound quality.
2.The system should have high output power.
3.The system should be easy to install.
4.The system should have low cost.
19

20.  Examined more advanced methods that are
used to analyze and refine requirements
 Addresses tradeoffs between engineering and
marketing requirements, tradeoffs between
engineering requirement themselves and
benchmarking
20

21. Output Power
, Efficiency
Install Time
Dimensions
THD
Cost
- + + - - -
1) Sound Quality + ↑↑ ↓ ↓↓ ↓↓
2) High Power + ↓ ↑↑ ↑ ↓↓ ↓
3) Install Ease + ↓ ↑↑ ↑ ↓
4) Cost - ↓↓ ↓ ↓ ↓ ↑↑
21

22. Output Power
, Efficiency
Dimensions
Install Time
THD
Cost
- + + - - -
THD - ↓ ↓ ↓
Output Power + ↑ ↓ ↓
, Efficiency + ↑ ↓
Install Time - ↓
Dimensions - ↓
Cost -
22

23. Apex Audio Monster Amps Our Design
THD 0.05% 0.15% 0.1%
Power 30W 50W 35W
Efficiency 70% 30% 40%
Cost $250 $120 $100
23

24. A complete requirements document will contain:
 Needs, Objectives, and Background (See Chapter 2).
 Requirements.
◦ marketing requirements
◦ engineering requirements
 Should be abstract, verifiable, and traceable
 Some maybe constraints
 Some may be standards
◦ Advanced analysis
 Engineering-marketing tradeoffs
 Engineering-engineering tradeoffs
 Benchmarks
24

25.  Properties of engineering requirements
 Examples of engineering requirements
 Properties of the Requirements Specification
 Advanced Requirements Analysis
◦ Tradeoff matrices
◦ Benchmarks
25