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A Performance Analysis System for the Sport of Bowling

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2.3.4 Communications<br />

The SMARTDOT module must transfer <strong>the</strong> data it collects to an external device <strong>for</strong><br />

archival, analysis, and display. The module must be able to detect <strong>the</strong> presence <strong>of</strong> <strong>the</strong><br />

external communications device, and both receive commands from it, and transmit data<br />

to it. Communications occur in a non-contact (wireless) fashion, and a light-based<br />

(infrared) communications scheme is used. The on-board transceiver consists <strong>of</strong> <strong>the</strong><br />

previously described light sensor and two visible red (660 nm) LEDs. An algorithm has<br />

been developed that relies on <strong>the</strong> on-board transceiver to detect <strong>the</strong> presence <strong>of</strong> <strong>the</strong><br />

external communications device (COMM wand), and initiate communication.<br />

2.4 CAPABILITIES<br />

The module is intended to detect and record (at least some <strong>of</strong>) <strong>the</strong> major <strong>for</strong>ces that <strong>the</strong><br />

ball experiences. A bowler attempts to exert various <strong>for</strong>ces on a bowling ball during<br />

delivery, to varying degrees, in a controlled manner. These <strong>for</strong>ces are:<br />

• Lift: Force applied to cause <strong>the</strong> ball to rotate about a primary axis relative to <strong>the</strong><br />

finger holes. The more lift that is applied to <strong>the</strong> ball at release, <strong>the</strong> faster <strong>the</strong> ball<br />

rotates as it travels down <strong>the</strong> lane.<br />

• Turn: The amount by which <strong>the</strong> axis <strong>of</strong> rotation <strong>of</strong> <strong>the</strong> ball is rotated away from<br />

normal with respect to <strong>the</strong> length <strong>of</strong> <strong>the</strong> bowling lane. The more turn that is<br />

applied at release, <strong>the</strong> more <strong>the</strong> ball has <strong>the</strong> potential to hook.<br />

• Tilt: The amount by which <strong>the</strong> axis <strong>of</strong> rotation is tilted away from parallel with<br />

<strong>the</strong> lane surface. The amount <strong>of</strong> tilt directly impacts how long <strong>the</strong> ball delays<br />

(skids or slides) be<strong>for</strong>e starting to hook.<br />

• Velocity: The speed and direction with which <strong>the</strong> ball leaves <strong>the</strong> bowler's hand.<br />

The higher <strong>the</strong> velocity, <strong>the</strong> harder <strong>the</strong> ball hits <strong>the</strong> pins, but <strong>the</strong> less it hooks. The<br />

velocity consists <strong>of</strong> a large x-coordinate component (towards <strong>the</strong> pins) and a small<br />

(but not insignificant) y-component (towards ei<strong>the</strong>r gutter). The x-component is<br />

always positive, originating at <strong>the</strong> foul line and running towards <strong>the</strong> pins. The y-<br />

component can be negative (toward <strong>the</strong> right gutter <strong>for</strong> a right-handed bowler) or<br />

positive (toward <strong>the</strong> left gutter <strong>for</strong> a right-hander).<br />

• L<strong>of</strong>t: The distance <strong>the</strong> ball travels (in <strong>the</strong> air) be<strong>for</strong>e it first makes contact with<br />

<strong>the</strong> lane after release. A bowler can control <strong>the</strong> amount a ball hooks by altering<br />

<strong>the</strong> distance <strong>the</strong> ball is l<strong>of</strong>ted be<strong>for</strong>e it hits <strong>the</strong> pins. More l<strong>of</strong>t generally means<br />

less hook.<br />

The basic premise behind <strong>the</strong> SMARTDOT module is that two sensors, an ambient light<br />

sensor and a piezoelectric pressure/impact sensor, combined with an accurate time<br />

source, are sufficient to accurately capture <strong>the</strong> amount <strong>of</strong> lift applied to <strong>the</strong> ball (<strong>the</strong><br />

angular velocity), <strong>the</strong> moment <strong>of</strong> release, and <strong>the</strong> various times <strong>of</strong> impact with <strong>the</strong> lane<br />

and <strong>the</strong> pins. It was not expected that this combination <strong>of</strong> sensors would be capable <strong>of</strong><br />

reliably capturing <strong>the</strong> amount <strong>of</strong> turn, tilt, or <strong>the</strong> y-component <strong>of</strong> <strong>the</strong> ball's velocity.<br />

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