engr 111 lecture 2 reading: chapter 2, class notes
TRANSCRIPT
ENGR 111 Lecture 2
Reading: Chapter 2, Class notes
Lecture 2: Engineering Design
Why? What? How?Primary goal: solve practical problems
Contrast with Scientists: Understand basic phenomena or natural world functions
Engineer’s creations used by peopleNeed to consider user’s needs
Engineers work within constraintsCost, time to market, usability, reliability,
performance,…
Example: Bad Design
Remotes to control home theater: cable, DVR, DVD, TV, audio, and VCR
The Solution?
Sofa saddle - available in sage, olive or ivory
Engineering Design
Fashioning a product for a practical goal under constraintsExample: Build a functioning canoe made of
concreteExample: Build a remote controlled robot that
navigates a maze, spending less than $50Example: Build a structure to safely drop an
egg from a height, using only supplied materials
Engineering Design
Have to Understand the Science and be able to ApplyExample: Canoe: hydrodynamics, buoyancyExample: Robot: mechanics, signal propagation Example: Egg Drop: aerodynamics, potential
and kinetic energy
Engineering Design Process
Statement of the problem:Design a system for counting the number of
people going through a door
How to arrive at the problem:User’s needsPerceived/anticipated need by usersVision of technology progressFeasibility: can this be done, can this be sold?
Recognize and understand the problem
Engineering Design Process
Develop Product SpecificationsConsider Goals and Constraints
Goals (for door counter):Total all people, regardless of size, weight?Total people entering or exiting the door?Number of times door opened enough?Operate 24/7?
Engineering Design Process
Constraints:How much can we spend on the product?
Development cost vs. manufacturing costHow much time do we have to design, produce,
test and deploy?How many units can we sell?Can the detector be visible to people?What are environmental conditions, lighting?How should the total be presented?
A counter? Over the network? Display visible to everyone?
Engineering Design Process
Constraints:How long should the counter operate?Is the counter reset every day – how many
digits?How reliable should it be – is it ok if repairs or
maintenance take it down once a month?Cost constraints for training, maintaining,
repairing the device?
Engineering Design Process
The product/design specifications take the goals and constraints into account:Detector should count people, not be visible,
counter should be visible to everyone, reset every night at 12AM automatically, operate in different lighting conditions, cost less than $50, repair/maintenance cost should be close to zero, etc…
Engineering Design Process
Develop Project PlanBased on the specifications, develop a plan to
complete the projectHow many people are needed to design,
produce, test, measure, verify, etc.How much time devoted to different pieces of
the project - schedule
Engineering Design Process
High-Level DesignDesign the product at a high level
What are the different approaches, what may meet the goals best within the constraints
Example: Should the counter be photo-detector based electronic counter, a mechanical counter based on door opening, …
Evaluate the different design tradeoffs to choose one
Specify block level components/pieces needed
Engineering Design Process
Detailed DesignProduce detailed design of different
blocks/pieces of the design Example: what photo detector to use, what type
of electronic display to use, what kind of manual overrides to provide, …
Engineering Design Process
Evaluate and Select design choicesPut the detailed designs together and
evaluate themPick the best among available alternativesIf goals not met, redesign…Design Process is iterative, always
considering tradeoffs…
Engineering Design Process
Test, Verify the designDeploy a prototype to test and verify the designOr use CAD tools to simulate the design
Manufacture and DeployMake sure the product is manufactured as
designed, test and verify the product
Engineering Design Process
Determine Needs
Create Specifications
Develop Plan
High-level Design
Detailed Design
Select BestAlternative
Test, Verify
Manufacture
Deliver
Summary of Design Process
Start with user’s needsFactor in Goals and ConstraintsPlan for the projectHigh-level design, more detailed design…Evaluate, test, verifyPick best alternatives, consider tradeoffs,Manufacture, deliverIterative design process, provide feedback to
different stages
Other Considerations
Scalability – can we scale the design to larger systems, many more systems, etc.Important in computer systems, networks
Expandability – what if we have more resources available in the future?Transistors on a chip, bits on a disk, data rate,
etc.
Problem Solving Approaches
Divide and ConquerBreak problems into smaller ones that can be
solved more easily or for which we have solutions
Put the smaller pieces together to find solutionExample: Fastest route to Navasota is via SH6.
Use that as part of fastest route to Houston.
Problem Solving Approaches
LayeringOrganize the solution into layersLayers can be specialized to draw on expertiseClear, well-defined interfaces between layers
allows independent designExample: used widely in computer systems,
networking, software…
Problem Solving Approaches
Transpose the problem into another domain where solution may be knownExample: Packet routing in a network akin to
routing US mail?
KISS (Keep It Simple and Stupid)Simple solutions easy to design, test, verify,
manufacture, less likely to fail…Werner von Braun said the Saturn V main
engines were designed to be “too dumb to fail”
The Best Product Design…
Sony Walkman (1979) – first really portable music player (cassette)Invented the marketBut don’t try to jog
with it – you will whack yourself with it!
…Keeps Changing With Time…
Available in assorted fruit flavors
…Keeps Changing With Time…
…Keeps Changing With Time…
…With Mistakes Along the Way…
Sony Discman D-50 (1984), first “portable” CD playerDefinitely don’t try to jog
with it! I paid ~$250 ($500 today)CDs cost $13 ($25 today)
…Including Some Big Ones