A Performance Analysis System for the Sport of Bowling
A Performance Analysis System for the Sport of Bowling
A Performance Analysis System for the Sport of Bowling
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Light Level<br />
100<br />
90<br />
80<br />
70<br />
60<br />
50<br />
40<br />
30<br />
20<br />
10<br />
0<br />
Release<br />
Point<br />
-50 0 100 200 300 400 500 600 700 800<br />
Milliseconds (since Release)<br />
Figure 3-2: Raw Data Release Region (800 ms)<br />
By considering <strong>the</strong> nature <strong>of</strong> <strong>the</strong> ideal wave<strong>for</strong>m (an increasing frequency "chirp"), it is<br />
possible to deduce <strong>the</strong> shape <strong>of</strong> <strong>the</strong> frequency spectrum <strong>of</strong> <strong>the</strong> raw data. Since <strong>the</strong> lane is<br />
more heavily oiled near <strong>the</strong> foul line, <strong>the</strong> coefficient <strong>of</strong> friction is lower, and <strong>the</strong> ball will<br />
slide more. This sliding prevents <strong>the</strong> ball's linear momentum from being transferred into<br />
angular momentum, thus maintaining a fairly constant velocity <strong>for</strong> <strong>the</strong> first few<br />
revolutions <strong>of</strong> <strong>the</strong> ball. Thus, a fundamental frequency is established that is close to <strong>the</strong><br />
initial angular velocity at release.<br />
140<br />
120<br />
100<br />
Impact<br />
(Head Pin)<br />
Light Level<br />
80<br />
60<br />
40<br />
20<br />
0<br />
2000<br />
2100 2200 2300 2400 2500 2600 2700 2800<br />
Milliseconds (since Release)<br />
Figure 3-3: Raw Data Impact Region (800 ms)<br />
As <strong>the</strong> ball continues down <strong>the</strong> lane, it eventually gains angular velocity, and this change<br />
will be reflected in additional higher frequency content, albeit with a decreasing<br />
magnitude, in <strong>the</strong> frequency bands immediately adjacent to <strong>the</strong> fundamental frequency.<br />
Due to <strong>the</strong> harmonic content introduced by <strong>the</strong> sharp peaks and multiple local peaks,<br />
<strong>the</strong>re should be additional frequency content at integer multiples <strong>of</strong> <strong>the</strong> fundamental<br />
frequency, appearing as an attenuated "echo" <strong>of</strong> <strong>the</strong> shape <strong>of</strong> <strong>the</strong> frequency content<br />
around <strong>the</strong> fundamental. The characteristic frequency spectrum shape just described is<br />
shown in Figure 3-4.<br />
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