Download Reminders

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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
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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
[email protected]
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Lego Car Design
Lego Car
Left Channel
Circuit
PC with sound card
Right Channel
DC motors
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Volume controls speed
Balance controls steering
Circuit converts sound wave to a drive signal
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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
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Start early on the design project!
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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
» Environmental risks
» Reliability
» Ease of use
– Design cost
– Material cost
– Assembly cost
»
»
»
»
Weight
Appearance
Performance
Safety
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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
Performance
Safety
DATUM
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
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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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Quiz
Put the following on each quiz:
Name
Lab 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
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