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April 25, 2003
physical computing
physical computing
tom igoe
http://itp.nyu.edu/tigoe/pcomp/
hardware hacking for those with little/no interest in electronics
What is physical computing?
Interaction - a cyclic process in which two actors alternatly listen, think and speak. (Chris Crawford)
Physical computing is mainly on the listen side.
Computer only sees us through what we do with our hands - no emotions.
Physical computing is different from robotics because:
PC - low autonomy of device, focus on input, simple programming, relies on user intell.
robotics - high autonomy, focus on output, complex programming, relies on device intelligence
Trying to overcome people's fear of technology. e.g. Squeak - trying to do it on the hardware side.
transduction - the conversion of one form of energy into another.
input - mech, heat, acoustic energy to electrical energy
output - in reverse
Forrest Mims III - publishes books called Engineer's mini notebooks
Microcontrollers
Microcontroller are just computers. I/O, CPU, power and memory.
Basic Stamp 2 - www.parallaxinc.com
[blinking an led is the hello world of physical computing]
BX-24 - www.basicx.com
PIC - www.microchip.com
javelin - www.parallaxinc.com - Java
Communication between people and devices
Sensors
Conscious vs uncoscious actions
conscious - sends the computer a message, physical affordance should be clear and obvious, sensing often in a very contained area - buttons, knobs, sliders, keys, card swipers
unconscious - action has other primary purpose, affordance not obvious, sensing may be across a wide area (too wide may result in false triggering) - door entry sensors, floor triggers, faucet sensors, motion detectors
discrete vs continuous (digital vs analog)
discrete sensors - buttons, toggles
continuous - sliders, pots, knobs - accuracy constrained by a-to-d conversion
how much resolution do you need? double it.
ambient heat and light is easy but real world is messy (smoothe changes)
touch - capacitive field sensor (Quantum QT113H)
force-sensitive resistors interlinkrec.com flexiforce.com
flex sensors - jameco.com , digikey.com
conductive rubber - allcorp.com , surplus retailers
motion
infrared ranger - sharp gp2d12
radio shack ir motion detector - 49-426
others:
polaroid sonar ranger, ultrasonic ranger - acroname.com
object tracking
CMUCam - http://www-2.cs.cmu.edu/~cmucam/
software
trackthemcolors for director - smoothware.com
cyclops and jitter (Max/MSP) - cycling74.com
BigEye - stein.nl
acoustic sensing
simple - sound level through piezo microphone, multiple piezos for triangulation
complex - frequency analysis thru FFT (hard on a microcontroller)
hard part is balancing the input and output sides - each could take too much time
Communication between devices
normally serial
async - both devices have a clock
sync - one is master, sends clock pulse as well as data
ethernet - embeddedether.net , embeddedethernet.com , edtp.com/packetwhacker.htm
serial-to-ethernet - siteplayer.com - web interface, UDP, serial port
cobox micro - lantronix.com - no web interface, TCP send and receive, 2 serial ports
wireless
RF and IR
rf good for many to many, ir good for one to one
RF - abercom (?) links/lynx (?)
accelerometers...
802.11b interface - iosoft.co.uk
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