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stanford hci group Feb 9, 2009 Björn Hartmann [email protected] Understanding & Modeling Input Devices

Stanford hci groupFeb 9, 2009 Björn Hartmann [email protected] Understanding & Modeling Input Devices

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Page 1: Stanford hci groupFeb 9, 2009 Björn Hartmann bjoern@cs.stanford.edu Understanding & Modeling Input Devices

stanford hci group Feb 9, 2009

Björn [email protected]

Understanding & ModelingInput Devices

Page 2: Stanford hci groupFeb 9, 2009 Björn Hartmann bjoern@cs.stanford.edu Understanding & Modeling Input Devices

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Questions for today

1. How do common input devices work?

2. How can we think about the larger space of all possible input devices?

3. Can we predict human input performance?

Next class: What about uncommon input devices (music controllers, multitouch, …)?

Page 3: Stanford hci groupFeb 9, 2009 Björn Hartmann bjoern@cs.stanford.edu Understanding & Modeling Input Devices

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Today’s lecture in graph form

time

Level of abstraction

concretedetails

abstractmodels Functional

Dissection of Mouse & Keyboard

Design Space of

Input Devices Modeling

Human Performance

Page 4: Stanford hci groupFeb 9, 2009 Björn Hartmann bjoern@cs.stanford.edu Understanding & Modeling Input Devices

I spilled coffee on my keyboard.

Now 25% of the keys don’t work anymore.

But some of the defective keys are nowhere near the spill.

What’s going on?

Page 5: Stanford hci groupFeb 9, 2009 Björn Hartmann bjoern@cs.stanford.edu Understanding & Modeling Input Devices

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Page 6: Stanford hci groupFeb 9, 2009 Björn Hartmann bjoern@cs.stanford.edu Understanding & Modeling Input Devices
Page 7: Stanford hci groupFeb 9, 2009 Björn Hartmann bjoern@cs.stanford.edu Understanding & Modeling Input Devices

Key cap

Top conductive layer

Bottom conductive layer

Separating layer(with hole)

Page 8: Stanford hci groupFeb 9, 2009 Björn Hartmann bjoern@cs.stanford.edu Understanding & Modeling Input Devices

Key cap

Top conductive layer

Bottom conductive layer

Separating layer(with hole)

Page 9: Stanford hci groupFeb 9, 2009 Björn Hartmann bjoern@cs.stanford.edu Understanding & Modeling Input Devices

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Page 10: Stanford hci groupFeb 9, 2009 Björn Hartmann bjoern@cs.stanford.edu Understanding & Modeling Input Devices

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Row/Column Scanning

Q W E R T

A S D F G

Z X C V B

R1

R2

R3

R4

C1 C2 C3 C4 C5

9 lines

20 keys

Page 11: Stanford hci groupFeb 9, 2009 Björn Hartmann bjoern@cs.stanford.edu Understanding & Modeling Input Devices

Mouse. Engelbart and English ~1964Source: Card, Stu. Lecture on Human Information Interaction. Stanford, 2007.

Page 12: Stanford hci groupFeb 9, 2009 Björn Hartmann bjoern@cs.stanford.edu Understanding & Modeling Input Devices

A Layered Framework

12From: Hartmann, Follmer, Klemmer: Input Devices are like Onions

Page 13: Stanford hci groupFeb 9, 2009 Björn Hartmann bjoern@cs.stanford.edu Understanding & Modeling Input Devices

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Page 14: Stanford hci groupFeb 9, 2009 Björn Hartmann bjoern@cs.stanford.edu Understanding & Modeling Input Devices

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Page 15: Stanford hci groupFeb 9, 2009 Björn Hartmann bjoern@cs.stanford.edu Understanding & Modeling Input Devices

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Right button

Left buttonEncoder wheel for scrolling

Page 16: Stanford hci groupFeb 9, 2009 Björn Hartmann bjoern@cs.stanford.edu Understanding & Modeling Input Devices

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IR emitter IR detectorslotted wheel(between emitter & detector)

Page 17: Stanford hci groupFeb 9, 2009 Björn Hartmann bjoern@cs.stanford.edu Understanding & Modeling Input Devices

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Sensing: Rotary Encoder

High

Page 18: Stanford hci groupFeb 9, 2009 Björn Hartmann bjoern@cs.stanford.edu Understanding & Modeling Input Devices

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Sensing: Fwd Rotation

Low

Page 19: Stanford hci groupFeb 9, 2009 Björn Hartmann bjoern@cs.stanford.edu Understanding & Modeling Input Devices

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Sensing: Backwd Rotation

Low Oops!

Page 20: Stanford hci groupFeb 9, 2009 Björn Hartmann bjoern@cs.stanford.edu Understanding & Modeling Input Devices

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Solution: Use two out-of-phase detectors

High

High

Page 21: Stanford hci groupFeb 9, 2009 Björn Hartmann bjoern@cs.stanford.edu Understanding & Modeling Input Devices

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Sensing: Rotary Encoder

Low

High

Page 22: Stanford hci groupFeb 9, 2009 Björn Hartmann bjoern@cs.stanford.edu Understanding & Modeling Input Devices

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Sensing: Rotary Encoder

High

Low

Coding:HH-> LH: dx = 1HH-> HL: dx = -1

Page 23: Stanford hci groupFeb 9, 2009 Björn Hartmann bjoern@cs.stanford.edu Understanding & Modeling Input Devices

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Transformation

cxt = max(0, min( sw, cxt-1+dx*cd ))

cyt = …

cxt: cursor x position in screen coordinates at time tdx: mouse x movement delta in mouse coordinatessw: screen widthcd: control-display ratio

Page 24: Stanford hci groupFeb 9, 2009 Björn Hartmann bjoern@cs.stanford.edu Understanding & Modeling Input Devices

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Device Abstraction Click, DoubleClick, MouseUp,

MouseDown, MouseMove …

Page 25: Stanford hci groupFeb 9, 2009 Björn Hartmann bjoern@cs.stanford.edu Understanding & Modeling Input Devices

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What about optical mice?

Source: http://spritesmods.com/?art=mouseeye

Page 26: Stanford hci groupFeb 9, 2009 Björn Hartmann bjoern@cs.stanford.edu Understanding & Modeling Input Devices

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bbbbbbbbbb

Source: http://spritesmods.com/?art=mouseeye

Page 27: Stanford hci groupFeb 9, 2009 Björn Hartmann bjoern@cs.stanford.edu Understanding & Modeling Input Devices

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Trackball, Trackpad

Page 28: Stanford hci groupFeb 9, 2009 Björn Hartmann bjoern@cs.stanford.edu Understanding & Modeling Input Devices

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Trackpoint Indirect, force sensing, velocity

control Nonlinear transfer function

Force

Velo

city

(cc) Image by flickr user tsaiid

Page 29: Stanford hci groupFeb 9, 2009 Björn Hartmann bjoern@cs.stanford.edu Understanding & Modeling Input Devices

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Joysticks

Page 30: Stanford hci groupFeb 9, 2009 Björn Hartmann bjoern@cs.stanford.edu Understanding & Modeling Input Devices

A design space of input devices…

Card, S. K., Mackinlay, J. D., and Robertson, G. G. 1991. A morphological analysis of the design space of input devices. ACM TOIS 9, 2 (Apr. 1991), 99-122.

Page 31: Stanford hci groupFeb 9, 2009 Björn Hartmann bjoern@cs.stanford.edu Understanding & Modeling Input Devices
Page 32: Stanford hci groupFeb 9, 2009 Björn Hartmann bjoern@cs.stanford.edu Understanding & Modeling Input Devices

Implicit Assumptions: Desktop-centric computing

Page 33: Stanford hci groupFeb 9, 2009 Björn Hartmann bjoern@cs.stanford.edu Understanding & Modeling Input Devices

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Which device is fastest? For what task? Pointing.

Combination of two factors: Bandwidth of human muscle group

(upper limit) Bandwidth of device itself

Page 34: Stanford hci groupFeb 9, 2009 Björn Hartmann bjoern@cs.stanford.edu Understanding & Modeling Input Devices

Bandwidth of Human Muscle Groups

Source: Card, Stu. Lecture on Human Information Interaction. Stanford, 2007.

Page 35: Stanford hci groupFeb 9, 2009 Björn Hartmann bjoern@cs.stanford.edu Understanding & Modeling Input Devices

Fitts’ Law Time Tpos to move the hand to

target size S which is distance D away is given by: Tpos = a + b log2 (2D/S)

Time to move the hand depends only on the relative precision required

Source: Landay, James. “Human Abilities”. CS160 UC Berkeley.

Page 36: Stanford hci groupFeb 9, 2009 Björn Hartmann bjoern@cs.stanford.edu Understanding & Modeling Input Devices

Mouse vs. Headmouse

Source: Card, Stu. Lecture on Human Information Interaction. Stanford, 2007.

Page 37: Stanford hci groupFeb 9, 2009 Björn Hartmann bjoern@cs.stanford.edu Understanding & Modeling Input Devices

Headmouse: No chance to win

Source: Card, Stu. Lecture on Human Information Interaction. Stanford, 2007.

Page 38: Stanford hci groupFeb 9, 2009 Björn Hartmann bjoern@cs.stanford.edu Understanding & Modeling Input Devices

Fitts’ Law in Windows & Mac OS

                                                     

Windows 95: Missed by a pixelWindows XP: Good to the last drop

The Apple menu in Mac OS X v10.4 Tiger.

Source: Jensen Harris, An Office User Interface Blog : Giving You Fitts. Microsoft, 2007; Apple

Page 39: Stanford hci groupFeb 9, 2009 Björn Hartmann bjoern@cs.stanford.edu Understanding & Modeling Input Devices

Fitts’ Law in Microsoft Office 2007

                                          

        Larger, labeled controls can be clicked more quickly

                            

Mini Toolbar: Close to the cursor

                                       

                Magic Corner: Office Button in the upper-left corner

Source: Jensen Harris, An Office User Interface Blog : Giving You Fitts. Microsoft, 2007.

Page 40: Stanford hci groupFeb 9, 2009 Björn Hartmann bjoern@cs.stanford.edu Understanding & Modeling Input Devices

stanford hci group Feb 9, 2009

http://bjoern.org