1. Reading: Chapter 2, Class notes
ENGR 111 Lecture 2
Reading: Chapter 2, Class notes

2. 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 people
Need to consider user’s needs
Engineers work within constraints
Cost, time to market, usability, reliability, performance,…

3. Example: Bad Design
Remotes to control home theater: cable, DVR, DVD, TV, audio, and VCR

4. The Solution?
Sofa saddle - available in sage, olive or ivory

5. Engineering Design
Fashioning a product for a practical goal under constraints
Example: Build a functioning canoe made of concrete
Example: Build a remote controlled robot that navigates a maze, spending less than $50
Example: Build a structure to safely drop an egg from a height, using only supplied materials

6. Engineering Design Have to Understand the Science and be able to Apply
Example: Canoe: hydrodynamics, buoyancy
Example: Robot: mechanics, signal propagation
Example: Egg Drop: aerodynamics, potential and kinetic energy

7. 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 needs
Perceived/anticipated need by users
Vision of technology progress
Feasibility: can this be done, can this be sold?
Recognize and understand the problem

8. Engineering Design Process
Develop Product Specifications
Consider 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?

9. Engineering Design Process
Constraints:
How much can we spend on the product?
Development cost vs. manufacturing cost
How 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?

10. 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?

11. 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…

12. Engineering Design Process
Develop Project Plan
Based on the specifications, develop a plan to complete the project
How many people are needed to design, produce, test, measure, verify, etc.
How much time devoted to different pieces of the project - schedule

13. Engineering Design Process
High-Level Design
Design 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

14. Engineering Design Process
Detailed Design
Produce 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, …

15. Engineering Design Process
Evaluate and Select design choices
Put the detailed designs together and evaluate them
Pick the best among available alternatives
If goals not met, redesign…
Design Process is iterative, always considering tradeoffs…

16. Engineering Design Process
Test, Verify the design
Deploy a prototype to test and verify the design
Or use CAD tools to simulate the design
Manufacture and Deploy
Make sure the product is manufactured as designed, test and verify the product

17. Engineering Design Process
Determine Needs
Select Best
Alternative
Create Specifications
Test, Verify
Develop Plan
Manufacture
High-level Design
Deliver
Detailed Design

18. Summary of Design Process
Start with user’s needs
Factor in Goals and Constraints
Plan for the project
High-level design, more detailed design…
Evaluate, test, verify
Pick best alternatives, consider tradeoffs,
Manufacture, deliver
Iterative design process, provide feedback to different stages

19. 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.

20. Problem Solving Approaches
Divide and Conquer
Break problems into smaller ones that can be solved more easily or for which we have solutions
Put the smaller pieces together to find solution
Example: Fastest route to Navasota is via SH6. Use that as part of fastest route to Houston.

21. Problem Solving Approaches
Layering
Organize the solution into layers
Layers can be specialized to draw on expertise
Clear, well-defined interfaces between layers allows independent design
Example: used widely in computer systems, networking, software…

22. Problem Solving Approaches
Transpose the problem into another domain where solution may be known
Example: 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”

23. The Best Product Design…
Sony Walkman (1979) – first really portable music player (cassette)
Invented the market
But don’t try to jog with it – you will whack yourself with it!

24. …Keeps Changing With Time…
Available in assorted fruit flavors

25. …Keeps Changing With Time…

26. …Keeps Changing With Time…

27. …With Mistakes Along the Way…
Sony Discman D-50 (1984), first “portable” CD player
Definitely don’t try to jog with it!
I paid ~$250 ($500 today)
CDs cost $13 ($25 today)

28. …Including Some Big Ones