Reading: Chapter 2, Class notes 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 people Need to consider user’s needs Engineers work within constraints Cost, 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 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

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

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

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?

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?

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 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

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

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, …

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…

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

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

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

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 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.

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…

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”

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!

…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 player Definitely don’t try to jog with it! I paid ~$250 ($500 today) CDs cost $13 ($25 today)

…Including Some Big Ones