New Human Computer Interfaces
Class ?
May 30 2007
Amnon Dekel
HUJI – CSE, Spring 2007
On the Menu
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Project Idea Presentations and
Discussion
Serial Communications:
Some more sensors
Changing the world: Actuators
Milestones for the rest of the semester
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Serial Communications
• The Ardiono can communicated with other
devices in the world using the Serial
Communications Protocol
• You can use this to have a board Send
data to another board and receive data
from another board.
• You can also use this to have the board
communicate with a workstation (Why?)
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Serial Communications
• This communication happens via the Arduino
board's serial or USB connection and on digital
pins 0 (RX) and 1 (TX). Thus, if you use these
functions, you cannot also use pins 0 and 1 for
digital i/o.
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Serial.begin(speed)
int Serial.available()
int Serial.read()
Serial.flush()
Serial.print(data)
Serial.println(data)
• WORKSHOP:
http://itp.nyu.edu/physcomp/Labs/Serial
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Some More About Sensors
Types
of
Input
Switches
Rocker switch
Push button
Slide switch
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Toggle switch
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Sensitive Switches
Roller switch
Hair trigger/whisker switch
Mercury/Tilt switch
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Magnetic/Reed switch
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Analog Sensors
Force Sensitive Resistor (FSR)
Pressure sensors
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Analog Sensors
Photocell
Temperature Sensor/Thermistor
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And more …
And more:
Capacitance
sensors
Piezoelectric
sensors
Accelerometers
Flex Sensor
More info: ITP Sensor Workshop Report
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Changing the World: Actuators
Examples
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Actuators
• Pneumatic
– Air Pressure causing movement
• Hydraulic
– Liquid Pressure causing movement
• Electronic
– Electro-magnetic movement
• Motors (Kinetic)
• Speakers (Audio)
• Lights (Visual)
More Info
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Motors
• Linear vs. Rotary movement
• Torque
• Gear
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Selecting a Motors
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Speed (RPM)
Movement – mechanics
Controlling the Position
Feedback about the position
How much weight can it carry
Torque
How much power does it need
Price
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Selecting a Motors
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Speed (RPM)
Movement – mechanics
Controlling the Position
Feedback about the position
How much weight can it carry
1. The moment of a force; the measure of a force's tendency to
torsion and rotation about an axis, equal to the vector
Torque produce
product of the radius vector from the axis of rotation to the point
of application
of the force
and the
force
vector.
How much
power
does
it
need
2. A turning or twisting force.
Price
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Types of Motors
DC
Stepper
DC servo
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Motors
DC Motor:
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Cheap.
Very easy to connect
Minimum control
Turns 360 degrees.
Can add components for more control:
– Speed: change the voltage using a POT
– Direction: change the polarity
– Position: can’t!  Add an H-Bridge circuit
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Motors
DC Servo:
• Expensive
• Very easy to connect
• Includes all components
• Turns 90 degrees to each side
• Full control:
– Speed: change the voltage
– Position: Needs CHECKING
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Controlling a Servo
DC Servo - Controlling the position:
• They rotate 0 to 180 degrees depending on the
pulsewidth. About 1.5 sec to move 180 degrees.
• The DC Servo takes a pulse of between 1-2 ms
every 20 ms.
• A pulse of 1 ms will turn the motor to 0 degrees;
1.5 MS will turn to 90 degrees, 2 ms will turn it to
180 degrees
• To keep a servo in its current position pulse it
with the same pulse width every 18-20 ms to
keep it there.
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Motors
Stepper:
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Cheap
Usually 12V
Hard to connect
Need extra components
Turns 360 degrees.
Can stay still in one position
Full control:
– Position
– Speed
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Controlling Motors
We want to control a few elements:
• Speed
• Strength
• Direction
• Position
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Controlling Motors
We want to control a few elements:
• Speed  power
• Strength  Current
• Direction  current direction/Pulse
• Position  Pulse
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Where to get motors?
‫חנויות טיסנים‬
‫חנויות רובוטיקה‬
‫חנויות אלקטרוניקה‬
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PAUSE
What have we been dealing with so far?
Sensing the world
Controlling the world
Vision
SOUND
Video
Pressure
Controlling
220V world
Analog
Output
Digital
Input
Computing
Change
Output to the
PC
Analog
INPUT
Digital
Output
Position
Communications
MOVEMENT
(Motors)
Movement
Audio
Temperature
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Projects
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What’s a good project?
Process
Milestones
Presentations
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What’s a Good Project
• Explores interesting, and preferably, novel
scenarios
• Shows interesting use of the technology
• Exhibits a working prototype for at least one
main part of the scenario.
• Explains how it fits into the wider scenario.
• Includes good documentation
– Project explanation, process, problems, code,
possible improvements
– Project Poster
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Project
• If we have time:
– Class Discussion of Projects
• Home Work:
– Prepare a Project Proposal:
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Intro – What problem am I trying to solve
Research (what exists…)
Concept
Technology
Milestones (7 weeks)
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