Finger swipe along a switch array. Extending Example 2.7, a linear switch array is 10 cm l...

Finger swipe along a switch array. Extending Example 2.7, a linear switch array is 10 cm long and has a resolution Rs = 2 switches/mm. A swipe motion is detected if the mid-point location changes by more than 8 switches. If the sampling period Ts = 0.1 s, what is the minimum finger swipe speed along the linear array that indicates a swipe motion?

Example 2.7

Finger swipes

As a finger moves across the array described in Example 2.6, the computer determines the finger midpoint positions every Ts = 0.05 seconds (s). A swipe is sensed when a midpoint position changes by more than four switch locations between position determinations, making xm = 4 switches. With Rs = 1 switch/mm, the minimum speed of a finger swipe is then

Multiple finger presses are computed in the same manner, but require a more powerful processor. Luckily, the power of newer processors increases, while the processor cost remains almost constant, allowing additional features to be included in new models for approximately the same price as the previous model.