SY DE 542 Controls March 14, 2005 R. Chow Email: chow@mie.utoronto.ca

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

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

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

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

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

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

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

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

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.

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?

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

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)

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?

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.

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.)