This question appears in Mumbai University > Human Machine Interaction subject

Marks: 10 M

Year: Dec 2011, May 2015

Characteristics of Device Based Controls:

1. Trackball
2. Joystick
3. Graphic Tablet
4. Touch Screen
5. Light Pen
6. Voice
7. Mouse
8. Keyboard

1) Trackball

Trackball is a spherical object (ball) that rotates freely in all directions in its socket.Direction and speed is tracked and translated into cursor movement.

Advantages

• Direct relationship between hand and pointer movement in terms of direction and speed.

• Does not obscure vision of screen.

• Does not require additional desk space (if mounted on keyboard).

Disadvantages

• Movement is indirect, in a plane different from the screen.

• Indirect relationship between hand and pointer movement in terms of distance.

• Requires a degree of eye-hand coordination.

• Requires different hand movements.

• May be difficult to control.

• May be fatiguing to use over extended time.

2. Joystick

• A stick or bat-shaped device anchored at the bottom.
• Variable in size, smaller ones being operated by fingers, larger ones requiring the whole hand.
• Variable in cursor direction movement method, force joysticks respond to pressure, moveable ones respond to movement.
• Variable in degree of movement allowed, from horizontal-vertical only to continuous.

Advantages

• Direct relationship between hand and pointer movement in terms of direction.
• Does not obscure vision of screen.
• Does not require additional desk space (if mounted on keyboard).

Disadvantages

• Movement is indirect, in a plane different from the screen.
• Indirect relationship between hand and pointer movement in terms of speed and distance.
• Requires a degree of eye-hand coordination.
• Requires different hand movements.
• May be slow and inaccurate.
• May be fatiguing to use over extended time.

3.Graphic Tablet

• Pressure-, heat-, light, or light-blockage-sensitive horizontal surfaces that lie the desktop or keyboard.
• May be operated with fingers, light pen, or objects like a stylus or pencil.
• Pointer imitates movements on tablet.

Advantages

• Direct relationship between hand and pointer movement in terms of direction, distance and speed.
• Does not obscure vision of screen.
• More comfortable horizontal operating plane.

Disadvantages

• Movement is indirect, in a plane different from the screen.
• Requires a degree of eye-hand coordination.
• Requires hand to be removed from keyboard and keyboard keys.
• Requires different hand movements.
• Requires additional desk space.
• Finger may be too large for accuracy with small objects.

4.Touch Screen

A special surface on the screen sensitive to finger or stylus touches.

Advantages

• Direct relationship between hand and pointer location in terms of direction, distance and speed.
• Requires no additional desk space.
• Movement is direct, in the same plane as screen.
• Stands up well in high-use environments.

Disadvantages

• Finger may obscure part of screen.
• Finger may be too large for accuracy with small objects.
• Requires moving the hand far from the keyboard to use.
• Very fatiguing to use over extended period of time.
• May soil or damage the screen.

5. Light Pen

It is a special surface on a screen sensitive to the touch of a special stylus or pen.

Advantages

• Direct relationship between hand and pointer location in terms of direction, distance and speed.
• Requires minimal additional desk space.
• Movement is direct, in the same plane as screen.
• Stands up well in high-use environments.
• More accurate than finger touching.

Disadvantages

• Hand may obscure part of screen.

• Requires picking it up to use.

• Requires moving the hand far from the keyboard to use.

• Very fatiguing to use over extended period of time.

6. Voice

Automatic speech recognition by the computer.

Advantages

• Simple and direct.
• Useful for people who cannot use a keyboard.
• Useful when the user’s hands are occupied.

Disadvantages

• High error rates due to difficulties in recognizing boundaries between spoken words and blurred word boundaries due to normal speech patterns.
• Slower throughput than with typing.
• Difficult to use in noisy environments.
• Impractical to use in quiet environments.

7. Mouse

• A rectangular or dome-shaped, movable, desktop control containing from one to three buttons used to manipulate objects and information on the screen.

• Movement of screen pointer mimics the mouse movement.

Advantages

• Direct relationship between hand and pointer movement in terms of direction, distance and speed.
  • Does not obscure vision of screen.
• Permits a comfortable hand resting position.
• Selection mechanisms are included on mouse.

Disadvantages

• Movement is indirect, in a plane different from the screen.
• Requires a degree of eye-hand coordination.
• Requires hand to be removed from keyboard.
• May require long movement distances.
• Requires additional desk space.

8. Keyboard

It’s a standard typewriter keyboard and cursor movement keys.

Advantages

• Familiar and accurate.
• Does not take up additional desk space.
• Very useful for:
• Entering text and alphanumeric data.
• Inserting in text and alphanumeric data.
• Keyed shortcuts – accelerators.
• Keyboard mnemonics – equivalents.

Disadvantages

• Slow for non-touch-typists.
• Slower than other devices in pointing.
• Requires discrete actions to operate.

No direct relationship between finger or hand movement on the keys and cursor movement on screen in terms of speed and distance.