A Performance Analysis System for the Sport of Bowling

uploaded, processed, and analyzed in such a way as to yield results useful to the bowler.
See Figures 2-2a and 2-2b for an example of the module installed in the ball and rolling
down the lane. The dotted lines emanating from the finger hole indicate the module's
"viewing angle" for ambient light.
2.3.2 Sensing Release, Lane Impact, and Pin Impact
As previously presented, in order to limit the size of the battery, the module should
remain in an ultra-low power "sleep" state whenever the ball is not being held by the
bowler, or rolling down the lane. For the module to detect that the ball has been released,
it must have some means for identifying that the bowler has removed their fingers from
the ball. The light sensor could be used for this purpose, since the bottom of the finger
hole is dark while the bowler's finger is in the hole, and light(er) when the finger is
removed. However, to accomplish this task, the TSL251 must remain powered, even
while the module is asleep. This is not possible at the ultra-low standby current level (~1
µAmp) that is required for extended battery life.
The module also requires a means to detect impact with the pins (which also gives it the
capability of detecting impact with the lane). This "impact" sensor has been implemented
with a piezoelectric plastic film made from PVDF (polyvinylidene fluoride) [19]. This
film is inexpensive, durable, and requires no external power to generate a voltage signal
strong enough to wake up the module. Since it is piezoelectric, when pressure is applied
to the film, the film responds by producing a voltage proportional to the rate-of-change of
the pressure applied. With a piece of this film inserted between the outside of the finger
insert and the wall of the finger hole, it can sense not only the lane and pin impacts, but
also the bowler applying pressure to the insert. Since the film detects changes in
pressure, and not the applied static pressure, it can be placed between the insert and the
finger hole wall without concern that the static pressure of that placement might set off
the module. Refer to Figure 2-1 for the position of the piezoelectric film sensor.
Since the bowler must apply significant pressure to the insert during release, the impact
sensor also serves to wake up the module immediately before release. The light sensor is
then used to detect the moment of release by looking for a rapid increase in the light
level, from near or total darkness, to some higher level of light (or lesser level of
darkness).
2.3.3 Measuring Time and Recording Data
The microprocessor supplies the clock to measure time, and coordinates all of the various
activities required to make the module work. A stable time-source, currently a miniature
quartz crystal, serves as the basis for the microprocessor's clock. Additional external
non-volatile memory (EEPROM) is required for storing the sampled light waveform, the
impact data, and any configuration parameters that are required.
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