100 GPS-Measurement in alpine · Faculty of Sports an Health Sciences Technische Universität...
Transcript of 100 GPS-Measurement in alpine · Faculty of Sports an Health Sciences Technische Universität...
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Technische Universität München Faculty of Sports an Health Sciences
GPS-Measurement in alpine
skiing – possibilities and limits
Andreas Huber
Karl-Heinz Waibel
Dr. Peter Spitzenpfeil
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Outline Description of race courses
and estimation of ground
reaction forces by GPS-Data
and Video
• Recording GPS-Data by
commercial device
calculating slope-
parameter
• Recording video (TV-
signal)
calculating time/speed
Comparative Study on the
usability of different GPS-
Devices
• „Long-distance“-
Experiment
– Garmin
– Smartphone
– GPS-device
• „Giant-Slalom“-
Experiment
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• Search for possibilities to capture coordinates in alpine ski racing:
• Description of race courses
• Estimation of ground reaction forces by combining course setting data and intermediate times at the gates from video analysis
Introduction
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Used Devices
• GPS-Device: FRWD
O400
• Video: TV-Signal
(VHS, DVD)
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• Coordinates from GPS-Device: – North-South (m)
– East-West (m)
– Altitude (m)
– Accuracy: 0.5 m
Data (input)
• Videoanalysis:
– Time code (s) at the gates
– Accuracy: 0.02 s
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Calculation (distances and slope angle)
• Distance between the gates
• Distance longitudinal
• Distance lateral
• Slope declination
Gate B
Gate A
Gate C
Distance
Lateral Distance
Longitudinal
Distance
2/2/
x
y
z
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Calculation (radius and angles)
• Radius of the Circumcircle: – Gate
– P1 and P2: Half distance to the gate before and later
• Opening angle: – Angle: P1 , Gate, P2
• Curve angle: – Angle: P1 , CC, P2
M
Gate A
Gate C
Gate B
P1: half distance Gate A/ Gate B
P2: half distance Gate B/ Gate C
CC: center of circumcircle
Radius of turn Gate B
Opening angle Gate B
Curve angle Gate B
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Calculation (times)
• Time for the gate B:
– Time between half of
the distances (t2-t1)
Gate A
Gate C
Gate B
tA: time at Gate A
tB: time at Gate B
tC: time at Gate C
t1: time between Gate A and Gate B
t2: time between Gate B and Gate C
2/)(2/)(12 ABABCB tttttttt
2/)( AC tt
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• Velocity: distance at the circular arc divided by the time for the gate
• Radial Force:
• Radial Acceleration:
• Ground reaction force:
Calculation
GateBBBB trv /*
BBB rva /2
22
NR FFF
BBR rvmF /*2
Gz FFF
rvmFZ /2
)cos( gmFN
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0,0
200,0
400,0
600,0
800,0
1000,0
1200,0
-100,0 -80,0 -60,0 -40,0 -20,0 0,0 20,0 40,0 60,0 80,0 100,0
Tore
Lauf_rohdaten
Geländeübergang
Geländeübergang
Geländeübergang
ZIEL
START
Chart
Chart of the race course with additional
markers (transitions, position of coaches,
position of timing,…)
Chart: Finish at (0;0), Gates evenly ditributed
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Table of calculated parameters
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GS: Men Women
No difference in mean acceleration
Maximum velocity
Maximum acceleration
No difference in velocity
Min = 23m
Min = 27m
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SG: Men Women
Very high velocity (mean/ max) No difference in mean and max acceleration
Min
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Course setting
Difference in course setting -> -> Difference in stress
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Velocity Force Regulations
• High velocity:
– Course setting straight
– Slope declination medium flat
(after a steep section)
• High forces:
– Course setting narrow
– Slope declination steep
– Velocity medium
>3g in GS (>2.5g in SG)
average acceleration/ turn
• Regulations on material:
– Side cut
– Length
– Width
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• Base for further discussions regarding the regulations of material and course settings to improve the safety.
• Big influence of aero dynamical drag in SG (and even in GS)
• Calculation of constraint forces (drag and friction) in a next step
• Enormous loading -> preparation of strength and endurance is of extreme importance for the athletes
Conclusion
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Methods
„Long-distance“-Experiment
• „Sella Ronda“
• Time: ca. 7 h
• Distance: ca. 85 km
– Skiing/Lift: 55 km
– Bus: 30 km
• Ascending: 6.800 m
– 26 lifts
• Descending: 7.700 m
• Peak: 2.562 m
„Giant-Slalom“-Experiment
• GS-course
• 10 turns
• Time: ca. 32 s
• Distance: 350 m
• Descending: 100m
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Comparative Study
GPS-Watch
• Garmin
Forerunner 910XT
– 1 Hz
– +/- 3,66m
Smartphone
• Iphone 3
– 1 Hz
– +/- 5-10m
– iSki-Tracker
– Map to Snow
– Scout
GPS-Device
• 2D Datalogger
GPS-mouse
– 12 Hz
– +/- 1,5-2 m
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Bus
skiing
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Total Distance: 82,73 km
Time Moving : 7h 06min
Avg. Speed: 10,6 km/h
Max. Speed: 65,2 km/h
Altitude max.: 2.498 m
Altitude min: 1.196 m
Results: GPS-Device
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Results: Garmin Forerunner 910XT
Data
Distance
[km]
Time
[hh:mm]
Vmax
[km/h]
VØ
[km/h]
altitude
min [m]
altitude
max [m]
altitude
diff. [m]
ascend
[m]
descend
[m]
1 85,78 07:06 58,3 12,1 1.036 2.211 1.175 6.568 7.601
2 82,74 07:06 58,8 11,6 1.141 2.639 1.498 7.137 7.660
3 85,4 07:06 56,8 12,3 1.091 2.321 1.572 6.229 7.959
4 82,94 07:06 72,7 11,7 1.089 2.608 1.519 7.154 7.666
5 87,07 07:06 64,5 12,2 1.058 2.479 1.421 7.056 7.833
6 85,92 07:06 61,9 12 1.288 2.683 1.395 7.089 7.706
Ø 84,98 62,2 11,9 1.117 2.490 1.430 6.872 7.738
SD 1,75 5,86 0,28 90,91 189,68 140,74 383,81 133,36
SD% 2,1 9,4 2,4 8,1 7,6 9,8 5,6 1,7
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Results: Garmin Forerunner 910XT
Route
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Results: Garmin Forerunner 910XT
Route
46,45
46,5
46,55
46,6
46,65
46,7
46,75
46,8
11,7 11,75 11,8 11,85 11,9 11,95 12
late
ral
longitidinal
lateral and longitudinal data
Uhr 1
Uhr 2
Uhr 3
Uhr 4
Uhr 5
Uhr 6
Uhr 7
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Results: Smartphone
iSki-Tracker
Distance
[km]
Time
[hh:mm]
Vmax
[km/h]
VØ
[km/h]
altitude
min [m]
altitude
max [m]
ascend
[m] Lifts [n]
1 88,39 07:06 77 20 1.072 2.471 8.973 26
2 83,7 07:06 69 20 1.072 2.470 8.131 23
3 93,46 07:06 75 19 1.072 2.503 9.065 27
Ø 88,52 07:06 74 20 1.072 2.481 8.723 25
SD 3,99 0 3,40 0,47 0,00 15,33 420,29 1,70
SD% 4,5 0 4,6 2,4 0,0 0,6 4,8 6,7
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iSkiTracker: Route
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Results: Smartphone
MAPtoSNOW
Distance
[km]
Time
[hh:mm]
Vmax
[km/h]
VØ
[km/h]
Ascend
[m]
Descend
[m]
Asc-desc
diff [m]
Lifts
[n]
1 79,64 07:06 64,35 20,96 6.307 7.482 1.175 25
2 83,77 07:06 63,5 29,55 5.976 7.465 1.489 26
3 82,19 07:06 62,1 25,45 5.884 6.997 1.113 27
4 83,48 07:06 69 27,64 4.858 7.125 2.267 25
Ø 82 07:06 65 26 5.756 7.267 1.511 26
SD 1,63 0,00 2,59 3,20 541,94 211,24 459,16 0,83
SD% 2,0 4,0 12,4 9,4 2,9 30,4 3,2
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Comparison GPS Device Garmin ISkiTraker Map to Snow
Ø distance
[km] 82,73 84,98 86,05 82,27
Ø time
[h:mm] 7:06 7:06 7:06 7:06
Ø ascend
[m] k. A. 6.872 k. A. 5.755
Ø descend
[m] k. A. 7.738 8.552 7.267
Ø asc-desc
[m] k. A. 866 k. A. 1.512
Ø altitude
diff. max-min [m] 1.302 1.430 1.409 k. A.
Ø Vmax
[km/h] 65,2 62,2 74 65
Ø Vmean
[km/h] 10,6 11,9 20 26
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Total distance quite equal
Rough orientation possible
Altitude values very different
Speed verry different
Conclusion – Comparative Study
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„Giant-Slalom“-Experiment
• GS-course
• 10 turns
• Time: ca. 32 s
• Distance: 350 m
• Descending: 100m
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Distance [m] 0 50 100 150 200 250 300
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start Gate1 Gate2 Gate3 Gate4 Gate5 Gate6 Gate7 Gate8 Gate9
Sp
ee
d [
km
/h]
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Lap time Distance Altitude Altitude Altitude Altitude V_GPS V_GPS V_GPS
MIN MAX AVG Delta MAX AVG Delta
[s] [m] [m] [m] [m] [m] [km/h] [km/h] [km/h]
12 Hz 32,81 346 1868,4 1966,2 1929,5 97,8 55,7 38,1 55,7
1 Hz 33,00 311 1868,9 1966,2 1930,6 97,3 54,4 37,8 54,4
Diff -0,19 35 -0,5 0 -1,09 0,5 1,3 0,3 1,3
Diff % -0,58 10,12 -0,03 0,00 -0,06 0,51 2,33 0,79 2,33
Results
For exact measurements of position and speed, high frequencies are necessary!
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Thank you very
much for your
Attention