SY DE 542

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SY DE 542
Controls March 14, 2005 R. Chow Email
chow_at_mie.utoronto.ca
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Controls

• Interface displays controls
• Controls allow the user to do something but
  also visually display information
• control setting
• control response
• Controls are displays
• Display does not mean visual, could be haptic,
  auditory

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Types of Controls

• Binary
• 2 states that are mutually exclusive
• Pushbuttons, single radio buttons
• State implementation on/off, raised/depressed,
  lit/unlit

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Controls (and Displays) on the Airbus A320 Photo
from At the controls, Avino and Long (2001)
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Controls on the Space Shuttle Columbia Photo
from At the controls Avino and Long (2001).
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Types of Controls

• Discrete controls
• has a finite number of states (0, 1, 2, etc.)
• system can only be in 1/n states.
• E.g. Automobile transmissions
• Implementations knobs with stops, sliders that
  snap to a setting, real radio buttons
• show range of control, current setting

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Types of Controls

• Continuous Setting
• has an infinite number of states
• system can only be in 1 state
• E.g. Some radio volume buttons
• Implementations knobs without stops, sliders

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Types of Controls

• Continuous Tracking
• Continuous but user keeps using the control
• e.g. Steering wheel, dragging an object with
  mouse

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Control vs. Input Device

• Computers have two control layers
• Input device (usually mouse)
• Soft control (implementation of a control on the
  screen)
• Good implementation ensures compatibility between
  these

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Mouse

• Can click on/off ----gt good for binary control or
  discrete state selection
• can slide
• straight line easier (try drawing a circle
  freehand with a mouse) ---gt better for sliders
  than knobs.

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Soft Control Issues

• Analog/Digital control issues (precision, range,
  graphic fragment, form issues)
• Proximity to displayed information
• Population stereotypes
• Response speed - how fast is a double click,
  overscroll?

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Direct Manipulation Controls

• Incorporate the control into the display
• Tries to give the user the experience of less
  interface

DM control
Indirect controls
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Feedback Issues with Controls

• Know what is a control and what is not (mouse
  over)
• Know what is active and what is not (graying
  out/disable)
• Know when they have taken a control action,
  generated a control signal
• Be informed of the systems response to that
  signal (including time lag situations)

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Exercise

• Examine the controls provided by any of the
  software on your machine or the web.
• Can you find examples of
• Graying out
• Good feedback, bad feedback
• Direct manipulation
• Hard controls
• Other control issues?

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Design Exercise

• Mrs. Fields is continuing to upgrade the
  interface to her production line. (what a long
  project!) Its time to work on the controls.

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• The actions Mrs. Field takes are
• Change in oven temperature
• Change in line speed
• Changes to quantities of input materials (flour,
  sugar, chocolate chips etc.)
• Changes to mixing time and mixing style (e.g.
  blend, whip etc.)