1. SY DE 542 Controls March 14, 2005 R. Chow

2. 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

3. Types of Controls Binary 2 states that are mutually exclusive
Pushbuttons, single radio buttons
State implementation “on/off”, “raised/depressed”, “lit/unlit”

4. Controls (and Displays) on the Airbus A320
Photo from “At the controls”, Avino and Long (2001)

5. Controls on the Space Shuttle Columbia
Photo from “At the controls” Avino and Long (2001).

6. 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

7. 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

8. Types of Controls Continuous Tracking
Continuous but user keeps using the control
e.g. Steering wheel, dragging an object with mouse

9. 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

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

11. 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?

12. Direct Manipulation Controls
Incorporate the control into the display
Tries to give the user the experience of “less interface
“DM” control
Indirect
controls

13. 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 system’s response to that signal (including time lag situations)

14. 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?

15. Design Exercise
Mrs. Fields is continuing to upgrade the interface to her production line. (what a long project!) It’s time to work on the controls.

16. 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.)