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ContextAware Interaction Techniques in a Small Device

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Works by sensing capacitance at a pad or plate (any flat conductive area) ... In portrait orientation (but not Flat) For 0.5 seconds. Extremely natural interaction ... – PowerPoint PPT presentation

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Title: ContextAware Interaction Techniques in a Small Device


1
Context-Aware Interaction Techniques in a Small
Device
2
Reading
  • Ken Hinckley, Jeff Pierce, Mike Sinclair, and
    Eric Horvitz, "Sensing techniques for mobile
    interaction", Proceedings of UIST '00, November
    2000, pp. 91-100
  • http//doi.acm.org/10.1145/354401.354417
  • UIST 00 Best paper award

3
Sensing for Interaction Techniques
  • Simple sensors that tell about the context of
    interaction
  • In particular, aspects of how the device is being
    held
  • Used to improve interaction techniques
  • Holding the device in certain ways indicates what
    action is being performed
  • Or small set of possible / likely actions
  • In some cases can just do it
  • Very natural if done well
  • Other cases limited possibilities allow implicit
    mode switch, enabling of specific sensor / button
    / display alternatives, and/or other speedups or
    improvements

4
Sensing in a Modified PDA
5
Sensor SpecificsIR Proximity Sensor
  • Estimate of distance to an object
  • 5 to 40cm range
  • Has IR emitter (IR light modulated at 40Khz)
  • Similar to TV remote
  • And IR receiver (tuned to sense 40Khz only)
  • Works by measuring amount of reflection
  • Different readings for different surface types
    and sizes of object
  • But actually pretty consistent
  • Here we are mostly looking at the same thing
    (skin) anyway

6
Sensor SpecificsTouch Sensors
  • Two separate sensors
  • Holding sensor on back and sides
  • Bevel sensor at edge of screen
  • Works by sensing capacitance at a pad or plate
    (any flat conductive area)
  • Key point is that this changes when you are
    touching it vs. not and can be sensed
  • Sensor plate is done via conductive paint

7
Sensor SpecificsTilt Sensor
  • 2D Accelerometer (in plane of device)
  • Gravity provides constant acceleration (1G)
  • Direction of acceleration vector ? x,y tilt
  • Note cant tell direction of vector
  • Screen up vs. screen down is ambiguous
  • Could add sensor to provide this but they didnt
  • Also can detect patterns of movement
  • Done with single chip
  • Cheap and relatively easy
  • Implemented with MEMS
  • Lots of new sensors soon using this technology

8
Sensor Architecture
  • PIC micro-controller constantly reads sensors
    (400 samples / sec)
  • Reports values to PDA via serial port
  • Broker application on PDA receives and
    processes values
  • Then makes information available to other
    applications via API (see below)
  • Polled values or events

9
Processed Values From Sensors
  • Things taken directly from processed sensor data
    without recognition / inference
  • TiltAngleLR, TiltAngleFB
  • HzLR, MagnitudeLR, HzFB, MagnitudeFB
  • Dominant frequency and magnitude of movements
    (separate x,y measures)
  • Obtained via FFT over short window

10
Processed Values From Sensors
  • Proximity
  • Estimate in cm
  • ProximityState
  • Close
  • lt 7cm
  • InRange
  • 7-25cm
  • OutOfRange
  • Duration in that state

11
Contexts Inferred From Touch Sensors
  • Holding (duration)
  • From back / side sensor
  • Is user holding the device and if so how long
    have they been holding it
  • TouchingBezel(duration)
  • Similar for bezel touch sensor
  • Not considered to be touching it until duration
    gt 0.2 sec
  • They use dwell times like this in a number of
    places

12
Contexts Inferred From Tilt Sensor
  • LookingAt(duration)
  • Small range of angles appropriate for typical
    viewing and how long there
  • Touch requirements added to this in later
    iteration
  • Moving(duration)
  • Any movement and how long since last still period
  • Shaking
  • Device is being shaken vigorously
  • Walking(duration)
  • Detected by repetitive motion in 1.4-3Hz range

13
Contexts Inferred From Tilt Sensor
Angle
Looking at Display
Walking
Y (FB) Tilt
X (LR) Tilt
14
Interaction Techniques
  • Power on
  • Voice memo recording
  • Portrait / Landscape display mode selection
  • Scrolling
  • LCD contrast compensation
  • Display changes for viewing while walking

15
Power On
  • PIC processor is on even when PDA is off
  • PDA is powered up when you pick it up to use it
  • Holding in orientation for use
  • Specifically
  • Holding LookingAt
  • In portrait orientation (but not Flat)
  • For 0.5 seconds
  • Extremely natural interaction
  • Pick it up and its ready to use
  • Avoids most false positives

16
Voice Memo Recording
  • Interaction Pick it up like a cell phone and
    talk into it
  • Holding Proximity proper orientation (tilt)
  • Has audio feedback (critical)
  • Click when pickup gesture recognized
  • Beep to start recording
  • Double beep at stop
  • Stop via loss of preconditions
  • Again, very natural interaction pick it up as
    necessary to do a particular thing and it does it

17
Display Mode Selection
  • DisplayOrientation event / data
  • Flat, PortraitPortraitUpsideDown,LandscapeLeft,
    LandscapteRight
  • Also refresh event when changed
  • Dead zones important
  • Must cross all the way through zone to count
  • Flat is important
  • dont change
  • Interacts with scrolling (next)

18
Tilt Scrolling
  • Must explicitly touch bezel touch area to enable
  • Not quite as nice, but still pretty easy
  • Then tilt up, down, left, right to scroll
  • Rate controlled (exponential) with a dead band
  • Extra touch LCD contrast compensation

19
Technique Interference
  • Tilt for scrolling interferes with display
    orientation selection
  • Hence explicit clutch
  • Also Im scrolling now event for explicit
    disabling across applications
  • BUT what about when you let go
  • Cant tilt back prior to releasing clutch
  • Not scrolling anymore once released
  • Handled by basically disallowing display change
    in direction of scroll tilt immediately after a
    scroll
  • Also suggest a timeout for this effect

20
Display Changes for Viewing While Walking
  • Future work in the paper
  • but I got a demo
  • If you hold the device in reading orientation
  • Hold LookingAt
  • and walk, it will increase font size, etc.
  • Again, detected by repetitive motion in 1.4-3Hz
    range

21
Lessons and Issues
  • Sensor fusion
  • Typically need multiple points of evidence for a
    situation in order to avoid false positives
  • E.g., looking at via both angle and touching
    instead of just angle
  • Need designs that are tolerant of recognition
    errors
  • False positive or negative is not a catastrophe
  • In general recognition errors can easily ruin a
    good interaction
  • Recovery costs can easily destroy benefits

22
Lessons and Issues
  • Cross talk between techniques
  • Handled by explicit disabling
  • Event saying Were using that now
  • Used to disable other effect
  • Pretty ad hoc
  • This is a general issue that needs work
  • Probably needs some sort of general conflict
    resolution mechanism
  • But not clear what that is, or how to do it

23
Lessons and Issues
  • Big take away point
  • Knowing context of operation (e.g. how
    held)allows space of possible current
    interactions to be constrained
  • Less explicit actions required to invoke an
    action or provide a input
  • E.g., typically avoid button presses or other
    mode entry
  • Can result in simpler and more natural
    interaction
  • Best case Picking it up to do something causes
    the something to just happen

24
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