chapter  7
24 Pages

- Sensor- and Recognition-Based Input for Interaction

Sensors convert a physical signal into an electrical signal that may be manipulated symbolically on a computer. A wide variety of sensors have been developed for aerospace, automotive, and robotics applications (Fraden 2003). Continual innovations in manufacturing and reductions in cost have allowed many sensing technologies to žnd application in consumer products. An interesting example is the development of the ubiquitous computer mouse. Douglas Engelbart’s original mouse, so named because its wire “tail” came out of its end, used two metal wheels and a pair of potentio meters to sense the wheels rolling over a desk surface. Soon, mice used

a ball and a pair of optical encoders to convert the movement of the hand into digital signals indicating precise relative motion. Now, even the most inexpensive mice use a specialized camera and image-processing algorithms to sense motions at the scale of one one-thousandth of an inch several thousand times per second. Accelerometers, devices that sense acceleration due to motion and the constant acceleration due to gravity, are another interesting example. Today’s tiny accelerometers were originally developed for application in automotive air-bag systems. Digital cameras now incorporate accelerometers to sense whether a picture is taken in landscape or portrait mode, and save the digital photo

7.1 Introduction ..................................................................................................................................................................... 133 7.2 Sensors and Sensing Modes............................................................................................................................................. 134

7.2.1 Occupancy and Motion ........................................................................................................................................ 134 7.2.2 Range Sensing ..................................................................................................................................................... 135 7.2.3 Position ................................................................................................................................................................ 135 7.2.4 Movement and Orientation .................................................................................................................................. 136 7.2.5 Touch.................................................................................................................................................................... 136 7.2.6 Gaze and Eyetracking .......................................................................................................................................... 137 7.2.7 Speech .................................................................................................................................................................. 137 7.2.8 Gesture ................................................................................................................................................................. 137 7.2.9 Identity ................................................................................................................................................................. 138 7.2.10 Context ................................................................................................................................................................. 138 7.2.11 Affect ................................................................................................................................................................... 138 7.2.12 Brain Interfaces ................................................................................................................................................... 139

7.3 Signal Processing ............................................................................................................................................................. 139 7.3.1 Preprocessing ....................................................................................................................................................... 139 7.3.2 Feature Selection ................................................................................................................................................. 140 7.3.3 Classižcation and Modeling .................................................................................................................................141