A Performance Analysis System for the Sport of Bowling

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Also, there have been instances in AUTO mode where the module recorded what appeared to be the ball returning to and rolling on the ball return. SMARTDOT is activated on every impact (as well as when the finger insert is pressed), and one of these impacts can occur when the ball is hoisted from the subway up to the ball return. If the module is facing downward after this impact (so that the release level is not detected at start-up), and the ball rolls fast enough after start-up to satisfy the discrimination routine, a "misfire" results. If the module is in AUTO mode when this scenario occurs, the result is that the waveform from the ball just rolled is lost, overwritten by the "misfire" generated at the ball return. See the "Future Work" section for more information on revisions to the discrimination routine. An interesting observation from the waveform in Figure 2-9 is that the first complete revolution of the ball occurred before the ball hit the lane. Thus, this revolution has not yet been impacted by the interaction between the ball and the lane, and is truly representative of the angular velocity of the ball at release. 2.8.4 Waveform Shape The initial premise behind using a light sensor to detect revolution of the ball was that the digitized light waveform would be roughly sinusoidal in nature. Looking at Figures 2-9 and 2-11, the actual waveform is much "rougher" than anticipated. Figure 2-10 shows the first 800 msecs of a waveform, Figure 2-11 shows 800 msecs of the same waveform, centered at the ball's initial impact with the pins. 140 120 100 Last complete Revolution Impact (Head Pin) Light Level 80 60 40 20 0 2000 2100 2200 2300 2400 2500 2600 2700 2800 Milliseconds (since Release) Figure 2-11: Waveform Shape, Impact Region (800 ms) Although the captured waveform is not exactly sinusoidal, it exhibits some basic characteristics that are encouraging, such as a periodic oscillation, and a sinusoidal shape in the "valleys" of the waveform. A sinusoidal envelope closely approximating the digitized waveform is superimposed on the graphs, and the beginnings and endings of each complete revolution of the ball, located by the peaks in the sine wave, are demarcated in red. A digital filter applied to the captured data could extract the target sine wave. 32
By filtering the data, and then counting the number of samples between the peaks, it is possible to find the angular velocity (rpms) for each of the revolutions. In Figure 2-9, there are between 16 and 17 samples in each of the revolutions, and the time between samples is 8.333 msec (120 Hz sample rate), yielding an angular velocity of 424 to 450 rpms (7.06 - 7.50 Hz). In Figure 2-11, there are between 15 and 16 sample times, yielding an angular velocity of 450 to 480 rpms (7.50 to 8.0 Hz). One concern immediately apparent from the results just obtained is that by using the method described (measuring time by counting samples), a difference of one sample time resulted in a change of ~25-30 rpms over a range of 425-480 rpms (± 2.8%). A finer resolution in the angular velocity calculations is probably required. Another concern is developing a method for calculating appropriate cut-off frequencies for the digital filter. Suggestions for dealing with these problems are presented in Section III. 2.8.5 Communications The module's software UART has turned out to be quite reliable. In an infrared (IR) wireless environment, the proximity of the communicating devices and ambient background light infiltration are the two main concerns. The proximity of the devices is fixed at about 1 3 / 8 " (1.375"), as long as the user does not remove the COMM wand during communications. Normally, an IR filter would be used to block visible light, but in this application, detection of visible light is necessary. By having the module detect the presence of the COMM wand (by looking for a very low light level), the module can assure that background light infiltration has been reduced to an acceptable level before initiating communications with the wand. One recurring problem was encountered that will be fixed in a later version of the module software. During the upload portion of the "Transmit" command, if the COMM wand was moved such that light infiltrated during the wand's reception of the EEPROM contents, the data file could be corrupted without detection by the MASTER program. There is no handshaking going on during this portion of the exchange, and if the COMM wand is positioned just right, it is possible for the 120 Hz fluorescent noise to simulate repeated START bits. The wand continues to see START bits, and consequently continues to receive data until it has counted 512 bytes, at which time it proceeds to process the data. Suggested improvements for the communication routines are discussed in the "Future Work" section. 2.8.6 Battery Life A major design goal was to limit the overall current drawn by the module. Lithium coin cells are rated in milliamp-hours (the number of hours the battery can supply one milliamp of current while maintaining its rated battery voltage). Several different techniques were used to limit the current draw of the module. The TSL251 light sensor is turned off when not in use, reducing current draw by 800 µAmps. While the module is running, the 87C752's IDLE mode is used between sample times. This cuts the average current draw of the module from 3.5 mAmps to under 2.0 mAmps. Extensive use of time outs has also helped to limit the run time of the module. For any given shot, the average current draw is 2.5 mAmps for 3-4 seconds, yielding 7.5-10 mAmp-seconds per shot. 33
Page 1 and 2: The Pennsylvania State University T
Page 3 and 4: TABLE OF CONTENTS Section I: Introd
Page 5 and 6: LIST OF FIGURES Figure 2-1 SMARTDOT
Page 7 and 8: SECTION I: INTRODUCTION, BACKGROUND
Page 9 and 10: eceiver that stores, processes, and
Page 11 and 12: 1.3.2 Product Development Phase The
Page 13 and 14: SECTION II: COLLECTING THE DATA - T
Page 15 and 16: 2.2 Design Constraints The feasibil
Page 17 and 18: 2.3 SENSING REQUIREMENTS The module
Page 19 and 20: Pin Deck Light Foul Line Figure 2-2
Page 21 and 22: 2.4.1 Ambient Light Sensor The ambi
Page 23 and 24: 9 28 8 RST V CC V CC 5 6 hyst 7 3 +
Page 25 and 26: 2.6 HARDWARE/SOFTWARE INTERACTION D
Page 27 and 28: 2.6.3 Baud Rate The module communic
Page 29 and 30: Configuration settings and the samp
Page 31 and 32: 2.7.5 The Ball is Rolling If the wa
Page 33 and 34: covered by the wand). When the modu
Page 35 and 36: 2.8.1 Detecting Release Detecting t
Page 37: Light Level 100 90 80 70 60 50 40 3
Page 41 and 42: The 'F300x can write to any portion
Page 43 and 44: One possibility is to use a transfo
Page 45 and 46: 2.10 SUMMARY This portion of the re
Page 47 and 48: The ball's angular velocity increas
Page 49 and 50: Light Level 100 90 80 70 60 50 40 3
Page 51 and 52: the fundamental frequency has been
Page 53 and 54: Since the fundamental frequency and
Page 55 and 56: Figure 3-7: MASTER "Analysis" Scree
Page 57 and 58: known, the linear momentum (and thu
Page 59 and 60: In order to find the value for v 1
Page 61 and 62: 3.5 ASSUMPTIONS AND ERROR ANALYSIS
Page 63 and 64: 3.5.3 External Forces and Friction
Page 65 and 66: 3.6.1 Implementation and Performanc
Page 67 and 68: Figure 3-11a: Effects of Phase Shif
Page 69 and 70: 3.6.3 The "Perfect" Game to Analyze
Page 71 and 72: Since the change in angular velocit
Page 73 and 74: BIBLIOGRAPHY [1] United State Paten
Page 75 and 76: APPENDIX A - SMARTDOT MODULE EMBEDD
Page 77 and 78: Appendix A: SMARTDOT Module Embedde
Page 85 and 86: APPENDIX B - SMARTDOT MODULE SOURCE
Page 87 and 88: Appendix C: SMARTDOT Module Command
Page 89 and 90:
Figure C-3 Appendix C: SMARTDOT Mod
Page 91 and 92:
APPENDIX E - 300 GAME MASTER SCREEN
Page 93 and 94:
Appendix E: 300 Game Analysis Frame
Page 95 and 96:
Page 97:
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