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Announcements Reading assignments on the syllabus must be done BEFORE the lecture» Read Ch. 6 before next lecture» Read Ch. 4-5 before lab this week

Quiz is a way to check roll Each lab write-up due at beginning of next lab

Someone on each team must get two motors from the Scientific Supply Store in Saunders Hall» Need cash or check

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Announcements -- cont’d.

Links to professional organizations on web site» http://eng.auburn.edu/admin/ess/organizations/engorg.html

Lab sections and team assignments are on WebCT.» If not correct, send email to

dennets@auburn.edu

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Lego Car Design

Volume controls speed Balance controls steering Circuit converts sound wave to a drive signal

Left Channel

Right Channel

DC motors

Lego CarPC with sound card

Cir

cuit

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Competition Each team designs and builds a car

» Work on car done outside of class» Team must build the car with their own supplies

– No supplies are provided

Lectures/Labs 1-7 provide background material for the design project

Start early on the design project!

COMPETITION – (Tentatively) Thursday, April 21, 7PM

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Engineering Design Process

Identify Customer Needs

Establish Product Specification

Define Alternative Concepts

Select the Most Suitable Concept

Design/Integrate Subsystems

Build/Test Prototype

Design/Build Production

Produce

Track

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Engineering Design Process Example: Mousetrap

Identify customer needs.» “I want a device that gets rid of the mice in my

house.”» “I want a device that won’t hurt my toddler.”» “I want a device that won’t wake me up at

night.”

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Engr. Design Process (cont’d)

Establish product specification.» Device must kill the mouse.» Any moving parts must be inaccessible

to toddlers. » Any poison must be inaccessible to

toddlers and remain inaccessible when trap is handled.

» Device must be quiet

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Engr. Design Process (cont’d)

Define alternative concepts.» Spring-loaded trap is enclosed. Baffled door

keeps out small fingers and muffles mechanical spring noise.

» Poison is formed into a module that is affixed to a far corner of the trap away from reaching fingers.

» Laser zaps mouse when optical beam shows nothing in door of trap.

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Brainstorming

The brain uses two basic modes in the design process:

» creative mode

» critical mode These two modes work against each

other. Brainstorming separates the two

processes into different time frames.

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Engr. Design Process (cont’d)

Select the most suitable concept.» Cost

– Design cost

– Material cost

– Assembly cost

» Weight

» Appearance

» Performance

» Safety

» Environmental risks

» Reliability

» Ease of use

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Tradeoffs in Engineering Design

Examples: Cost vs. performance Safety vs. performance Performance vs. reliability

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Pugh Chart

Spring Poison Laser

Cost

DATUM

Performance

Safety

Reliability

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Engr. Design Process (cont’d)

Design the subsystems and integrate them» Break a complex system into small subsystems

– Optical sensing subsystem

– Decision logic

– Laser subsystem

– Mechanical packaging

Build and test a prototype» Build and test each subsystem» Integrate and test the subsystems

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Engr. Design Process (cont’d)

Design and build production facility. Produce and distribute. Track product and improve.

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Design for Lego Car

Specification is given. Define alternative concepts. Select the most suitable concept.

» Bottom line is finishing time.» “Cost” is figured in by penalizing use of parts.» Car should be sturdy enough not to fly apart

during race.» Car and course must pass minimal safety specs.

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Design Subsystems

Car path & steering strategy Type and number of wires connecting to amp. Type of waveform used to power car. Type of circuit & component values. Vehicle mass, wheels, etc.

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Further Design Steps

Build and test, then modify!!! Production design, distribution, and

tracking are not relevant to a single-shot prototype design.

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Circuit Basics

Electricity flows through a circuit just like water through a pipe. » charge -- water in a pipe» current -- water flow» voltage -- pressure» resistance -- inverse of pipe diameter» capacitance -- water stored under pressure

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Units

charge -- coulombs (C) current -- amperes (A), A=C/s voltage -- volts (V) resistance -- ohms (), =V/A capacitance -- farads (F), F = C/V

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Circuit Elements

voltage source (e.g. battery) -- water pump with specified pressure. Units: volts (V)

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Circuit Elements

resistor -- pipe with small diameter that makes water flow more difficult. Units: ohms ()

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QuizPut the following on each quiz:

NameLab Date and Time

1. (True or False) Engineering requires teamwork.

2. Which of the following is NOT one of the six main sub-areas of Electrical and Computer Engineering: a) Microelectronics, b) Electromagnetics, c) Control Systems, d) Physics, e) Power Systems