Biomechanical P ... Slalom Water Skiing R1.pdf - Atrium - University ...

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2 MethodsThe natural environment surrounding water skiing provided many challenges whendesigning an instrumentation system and methodology. The uncontrollable factors suchas weather, boat operation and fatigue were minimized with a highly structuredexperimental procedure. Instrumentation design choices were made considering that anyinstrument that was to be mounted to the ski or skier needed to be waterproofed, the dataneeded to be manipulated for analysis after each test day, the data needed to be collectedby a host computer and instruments needed to be able to withstand a harsh environment.Wind was monitored throughout each test day using a temporary data collection station.The station was located on a dock at a location that was exposed to the relatively samewind as where the subjects were skiing. Data was collected from an anemometer (#40C,NRG Systems Inc, Hinesburg, Vermont), located approximately six feet above thesurface of the dock, by a data logger (SynphoniePLUS, NRG Systems Inc, Hinesburg,Vermont). Wind effects were negligible because subjects were required to ski one runinto the wind and the other with the wind and the results from each test run wereaveraged.Determining what type of IMU to apply to a specific application is very important andthere are several commercial options available on the market. Each type has its own set ofpros and cons that need to be incorporated into the decision process. For this study themost desirable solution was a self contained product that required a minimal amount ofsignal conditioning after the signal was received from the unit.30
The product chosen that best met the requirements for this research was the Microstrain3DM-GX2 (Microstrain, Inc., Williston, Vermont). It is composed of an array ofmagnetometers, gyroscopes and accelerometers that allows it to output a wide range ofinertial measurements. The internal signal conditioning allows the sensor to be accurateand durable in a wide range of experimental environments and the commercial softwareprovided with the sensor allows for easy onsite parameter programming. The unit wasprogrammed to output 3D-acceleration, 3D-angular rate and an orientation matrix at arate of 20 Hz. This resulted in an effective data rate of 12.6 kbps.The IMU unit communicated with the host computer via a custom fabricated 2 GHz RFtransceiver system. The system used four transceiver modules (nRF2401, NordicSemiconductor ASA, Tiller, Norway), two on each breakout board, that were controlledby a microcontroller. The microcontroller implemented a custom control program and thetwo breakout boards were custom designed, by Groendyk, N. On each board, onetransceiver was designated as the receiver and the other the transmitter, allowing themicrocontroller to receive and send data simultaneously. This arrangement increased theefficiency of the system and allowed for the transmission of data at a high and sustainedthroughput rate. One transceiver system was connected directly to the IMU unit on theski using the RS232 protocol, and the other was connected to the computer in the boat viaa Universal Serial Bus (USB) port.31
Page 1 and 2: BIOMECHANICAL PERFORMANCE FACTORS O
Page 3 and 4: AcknowledgmentsI would like to star
Page 5: 6.1 Conclusion and Future Considera
Page 8 and 9: 83.42º·s and 48.92 º. There was
Page 10 and 11: List of TablesChapter 4Table 1: Sum
Page 12 and 13: 1.1 The Basics of Water SkiingWater
Page 15 and 16: deep water start a good performance
Page 17 and 18: skills in order to be able to ident
Page 19 and 20: completed their test runs throughou
Page 21 and 22: 1.5 Thesis outlineChapter 2 will pr
Page 23 and 24: Chapter 2: Literature Review13
Page 25 and 26: of material can be used as a force
Page 27 and 28: & Pesty, n.d.; Zang et al., 2004].
Page 29 and 30: instrumentation system used did not
Page 31 and 32: allowed them to plot a velocity ver
Page 33 and 34: Chapter 3: Methods and Instrumentat
Page 35 and 36: AbstractThere are many challenges w
Page 37 and 38: is most likely the main reason why
Page 39: applicable to dynamic sports [Brodi
Page 43 and 44: ON) that did not require any modifi
Page 45 and 46: single data collection program that
Page 47 and 48: Figure 3 - Diagram of slalom course
Page 49 and 50: for patterns in the data that sugge
Page 51 and 52: 200SU EC ST BTA150Angle (degrees)10
Page 53 and 54: 10050Angle (Degrees)0-50-100-150Pit
Page 55 and 56: RF communication systems are easily
Page 57 and 58: The roll profile can be used to det
Page 59 and 60: Chapter 4: Water Skiing Biomechanic
Page 61 and 62: AbstractSix advanced slalom skiers
Page 63 and 64: Recreational and competitive slalom
Page 65 and 66: Table 1: Summary of human participa
Page 67 and 68: Figure 2: Diagram of slalom course
Page 69 and 70: at a rate of 1 Hz (BG-331RGTGT, Mig
Page 71 and 72: adjusted p-value. (SAS Institue Inc
Page 73 and 74: Table 3: Summary of completed turns
Page 75 and 76: Rope load peaks during the cutting
Page 77 and 78: Peak skier velocity for each turn i
Page 79 and 80: 4 DiscussionThere are several varia
Page 81 and 82: trend was seen by Runciman (2011) w
Page 83 and 84: (p=0.2437 and p=0.246). It was expe
Page 85 and 86: velocity and low peak rope load. In
Page 87 and 88: improve the accuracy that a coach e
Page 89 and 90: Chapter 5: Biomechanical Analysis o
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AbstractWater skiing has received l
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ski manufacturers ability to compar
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given about how the effects of the
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tip. The IMU housing was wrapped in
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(roll, acceleration and deceleratio
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decrease. This portion of the turn
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Roll, Ski Acceleration and SkierVel
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Integral of Roll, Peak Roll (degree
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Integral of Roll, Peak Roll (degree
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Integral of Deceleration (m/s 2 *s)
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Figure 12 shows each ski’s overal
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Integral of Acceleration, Peak Acce
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Integral of Acceleration, Peak Acce
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peak velocity is also occurring at
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was not a significant difference be
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The lack of statistical significanc
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Chapter 6 - Conclusion and Future C
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The data, in combination with a sta
Page 127 and 128:
Bachmann, E.R. (2000). Inertial and
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Appendices119
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Load Transducer Output (V)0.80.70.6
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Skiing Background Information6. How
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Section 2 - Follow up surveyPlease
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Appendix C - Ski Survey ResultsThe
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