Post on 21-Dec-2015
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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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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