scholarly journals How far from the gold standard? Comparing the accuracy of a Local Position Measurement (LPM) system and a 15 Hz GPS to a laser for measuring acceleration and running speed during team sports

PLoS ONE ◽  
2021 ◽  
Vol 16 (4) ◽  
pp. e0250549
Author(s):  
Karin Fischer-Sonderegger ◽  
Wolfgang Taube ◽  
Martin Rumo ◽  
Markus Tschopp
Keyword(s):  
Gold Standard ◽  
Team Sports ◽  
Position Measurement ◽  
Running Speed ◽  
Measurement Systems ◽  
Maximal Acceleration ◽  
Standard Deviations

Purpose This study compared the validity and inter- and intra-unit reliability of local (LPM) and global (GPS) position measurement systems for measuring acceleration during team sports. Methods Devices were attached to a remote-controlled car and validated against a laser. Mean percentage biases (MPBs) of maximal acceleration (amax) and maximal running speed (vmax) were used to measure validity. Mean between-device and mean within-device standard deviations of the percentage biases (bd-SDs and wd-SDs) of amax and vmax were used to measure inter- and intra-unit reliability, respectively. Results Both systems tended to underestimate amax similarly (GPS: –61.8 to 3.5%; LPM: –53.9 to 9.6%). The MPBs of amax were lower in trials with unidirectional linear movements (GPS: –18.8 to 3.5%; LPM: −11.2 to 9.6%) than in trials with changes of direction (CODs; GPS: –61.8 to −21.1%; LPM: −53.9 to –35.3%). The MPBs of vmax (GPS: –3.3 to –1.0%; LPM: –12.4 to 1.5%) were lower than those of amax. The bd-SDs and the wd-SDs of amax were similar for both systems (bd-SDs: GPS: 2.8 to 12.0%; LPM 3.7 to 15.3%; wd-SDs: GPS: 3.7 to 28.4%; LPM: 5.3 to 27.2%), whereas GPS showed better bd-SDs of vmax than LPM. Conclusion The accuracy depended strongly on the type of action measured, with CODs displaying particularly poor validity, indicating a challenge for quantifying training loads in team sports.

scholarly journals Measuring Gait Velocity and Stride Length with an Ultrawide Bandwidth Local Positioning System and an Inertial Measurement Unit

Sensors ◽  
2021 ◽  
Vol 21 (9) ◽  
pp. 2896
Author(s):  
Pratham Singh ◽  
Michael Esposito ◽  
Zach Barrons ◽  
Christian A. Clermont ◽  
John Wannop ◽  
...  
Keyword(s):  
Gold Standard ◽  
Gait Speed ◽  
Inertial Measurement Unit ◽  
Stride Length ◽  
Measurement Unit ◽  
Gait Velocity ◽  
Positioning System ◽  
Inertial Measurement ◽  
Measurement Systems ◽  
Local Positioning System

One possible modality to profile gait speed and stride length includes using wearable technologies. Wearable technology using global positioning system (GPS) receivers may not be a feasible means to measure gait speed. An alternative may include a local positioning system (LPS). Considering that LPS wearables are not good at determining gait events such as heel strikes, applying sensor fusion with an inertial measurement unit (IMU) may be beneficial. Speed and stride length determined from an ultrawide bandwidth LPS equipped with an IMU were compared to video motion capture (i.e., the “gold standard”) as the criterion standard. Ninety participants performed trials at three self-selected walk, run and sprint speeds. After processing location, speed and acceleration data from the measurement systems, speed between the last five meters and stride length in the last stride of the trial were analyzed. Small biases and strong positive intraclass correlations (0.9–1.0) between the LPS and “the gold standard” were found. The significance of the study is that the LPS can be a valid method to determine speed and stride length. Variability of speed and stride length can be reduced when exploring data processing methods that can better extract speed and stride length measurements.

scholarly journals Individualized thresholds to analyze acceleration demands in soccer players using GPS (Umbrales individualizados para analizar las demandas en la aceleración en futbolistas usando GPS)

Retos ◽  
2018 ◽  
pp. 75-79
Author(s):  
F. Javier Núñez ◽  
Francisco J. Toscano-Bendala ◽  
Luis Suarez-Arrones ◽  
F. Ignacio Martínez-Cabrera ◽  
Moisés De Hoyo
Keyword(s):  
Physical Performance ◽  
Soccer Players ◽  
Running Speed ◽  
Maximum Acceleration ◽  
Gps Technology ◽  
Speed Test ◽  
Maximal Acceleration ◽  
Para Determinar ◽  
Acceleration Capacity ◽  
Individual Threshold

Abstract. The aim of the present study was to analyze the number and the % of maximum accelerations, and the distance covered among different soccer players’ positions, classifying them with GPS technology according to an individual threshold based on the maximum acceleration capacity. 20 players were observed during four matches (n=80). All players undertook a maximal running speed test to determine the maximal acceleration. Players’ activities during the matches were classified into four individual acceleration thresholds: acceleration starting from 0 to 13 km·h-1 and never reaching 18 km·h-1 (A1); acceleration starting from 0 to 13 km·h-1 and reaching 18 km·h-1 (A2); acceleration starting from 13 to 18 km·h-1 (A3); and acceleration starting above 18 km·h-1 (A4). During A1, Full-Backs performed a higher number of accelerations compared to other playing positions and reached a ~95% of the maximum acceleration. During A2, Full-Backs and Wide Midfielder performed a higher number of accelerations than Central Defenders and Forwards, and Central Midfielders reached an estimated intensity of 95% of the maximum acceleration. During A3, CM performed the highest number of accelerations compared to the rest of the groups, while F reached an estimated intensity of 78% of their maximum acceleration. This individualized threshold could help coaches assess players’ physical performance and improve it, or to avoid injuries.Resumen. El objetivo del presente estudio fue analizar el número, % de la aceleración máxima y la distancia recorrida por las diferentes posiciones de juego, clasificándolos según un umbral individual para cada jugador basado en la máxima capacidad de aceleraración usando la tecnología GPS. Un total de 20 jugadores fueron evaluados durante 4 partidos (n=80). Todos los participantes realizaron un sprint a la máxima velocidad de carrera para determinar su capacidad máxima de aceleración. La actividad de los jugadores durante los partidos fue dividida en 4 categorías individuales de aceleración: A1, aceleración de 0 a 13 km·h-1 y sin llegar a 18 km·h-1; A2, aceleración desde 0 hasta 13 km·h-1 y alcanzando 18 km·h-1; A3, aceleración que inicia desde los 13 km·h-1 hasta los 18 km·h-1; A4, aceleración que comienza a una velocidad >18 km·h-1. En A1, los defensas laterales realizaron un mayor número de aceleraciones en comparación con las otras demarcaciones de juego y logrando una intensidad ~ 95% de su aceleración máxima. En A2, los defensas laterales y centrocampistas laterales realizaron un mayor número de aceleraciones que los defensas centrales y delanteros, consiguiendo los centrocampistas una intensidad aproximada del 95% de su máxima aceleración. En A3, los centrocampistas realizaron una cantidad superior de aceleraciones que el resto de grupos, mientras que los delanteros lograron una intensidad aproximada del 78% de su máxima aceleración. Estos umbrales individualizados podrían ser de gran utilidad para permitir evaluar a los técnicos de forma más precisa el rendimiento físico de los jugadores, permitiéndoles con ello mejorar su rendimiento y prevenir lesiones en futbolistas.

Robust Position Measurement Systems based on Integrated 3D Magnetic Field Sensors

2011 ◽  
pp. 41-48
Author(s):  
Hans-Peter Hohe ◽  
Michael Hackner ◽  
Markus Stahl-Offergeld ◽  
Volker Peters ◽  
Josef Sauerer
Keyword(s):  
Magnetic Field ◽  
Position Measurement ◽  
Magnetic Field Sensors ◽  
Measurement Systems

scholarly journals Positional uncertainty in optical-based metrology systems in large volume manufacturing

ACTA IMEKO ◽  
2018 ◽  
Vol 7 (2) ◽  
pp. 84 ◽  
Author(s):  
Ainsley Miller ◽  
Anthony J Mulholland ◽  
Stephen Gareth Pierce ◽  
Ben Hughes ◽  
Alistair B Forbes
Keyword(s):  
Large Volume ◽  
Simulated Data ◽  
Ground Truth ◽  
Robotic Assembly ◽  
Position Measurement ◽  
Light Refraction ◽  
Laser Tracking ◽  
Measurement Systems ◽  
Industrial Setting ◽  
Modern Manufacturing

<p class="Abstract"><span lang="EN-US">Modern manufacturing increasingly utilizes automated systems for component positioning and assembly and a vital aspect of autonomous precision manufacturing is large volume metrology. One popular approach uses light rays, which travel through the volume of air, to calculate the position of an object of interest. These optical-based metrology systems such as photogrammetry and laser tracking are crucial in improving the accuracy and quality associated with robotic assembly. However, in an industrial setting, these positional measurement systems give rise to uncertainties which can in many instances be greater than the required tolerances. One source of this uncertainty is light refraction due (in part) to temperature fluctuations in the air. This paper will describe how COMSOL Multiphysics can be used to create simulated data with complete ground truth on the refractive index field in the volume, and will discuss the measurement uncertainties associated with these simulations. Over industry relevant distances (tens of metres) the uncertainty in the position measurement due to light refraction is of the order of a millimetre.</span></p>

scholarly journals Measuring Physical Load in Soccer: Strengths and Limitations of 3 Different Methods

2019 ◽  
Vol 14 (5) ◽  
pp. 627-634
Author(s):  
Karin Fischer-Sonderegger ◽  
Wolfgang Taube ◽  
Martin Rumo ◽  
Markus Tschopp
Keyword(s):  
Measurement System ◽  
Performance Indicators ◽  
High Speed ◽  
Absolute Threshold ◽  
Physical Load ◽  
Effect Sizes ◽  
Position Measurement ◽  
Running Speed ◽  
Discriminative Ability ◽  
Speed Effect

Purpose: To investigate the strengths and limitations of different indicators to measure physical load. Furthermore, indicators were evaluated for discrimination between performance levels and playing positions. Methods: Ninety positional match files from 70 elite players and 91 match files from 69 subelite players were collected during 14 official under-18 matches using a local position measurement system. Indicators are calculated from speed, absolute acceleration (acc-abs), or percentage acceleration (acc-%). The acc-% describes the level of acceleration depending on the maximal voluntary acceleration (amax) for each initial running speed. Effect sizes (ES) were used to determine discriminative ability. Results: The number of high accelerations largely depended on the method (absolute threshold [>3 m·s−2 and >4 m·s−2] 120 and 59 efforts; high percentage threshold [>75% amax] 84 efforts). Only a small number of highly accelerated efforts reached speeds considered high-speed running (>19.8 km·h−1: 32.6%). More high acc-% exists from initial running speed >2 m·s−1 (23.0) compared with acc-abs (>3 m·s−2 14.4, >4 m·s−2 5.9). Elite players achieve higher values in most performance indicators, with ES being highest for the number of high acc-% (ES = 0.91) and high acc-abs (>3 m·s−2 ES = 0.86, >4 m·s−2 ES = 0.87), as well as for covered distance in jogging (ES = 0.94). Conclusions: Estimated physical load, discriminative ability of physical indicators, and positional requirements largely depend on the applied method. A combination of speed-based and acc-% methods is recommended to get a comprehensive view.

Upper Limb Proprioceptive Acuity Assessment Based on Three-Dimensional Position Measurement Systems

Motor Control ◽  
2020 ◽  
Vol 24 (4) ◽  
pp. 605-623
Author(s):  
Lin Li ◽  
Yanxia Li ◽  
Chang-hong Wu ◽  
Hao Fu
Keyword(s):  
Upper Limb ◽  
Three Dimensional ◽  
Vertical Direction ◽  
Target Position ◽  
Position Measurement ◽  
Reproduction Task ◽  
Measurement Systems ◽  
Limb Position ◽  
History Of ◽  
Joint Range

The aim of the current work was to verify three-dimensional directional effects on the reproduction error precision of the human upper limb position. Thirty male subjects without history of upper limb pathology were recruited from Renmin University of China. A three-dimensional position reproduction task in six directions (up, down, left, right, far, and near) was performed by each subject. The results suggested that the proprioceptive sense of upper limb position depends on the direction, with smaller absolute errors in Directions 4 (right) and 5 (far) than in Directions 1 (up), 2 (down), 3 (left), and 6 (near). Proprioception near the end of the elbow joint range of motion may be more reliable and sensitive. Subjects reproduced fewer ranges in the horizontal plane (Directions 3, 5, and 6) and they overshot the target position along the z-axis (vertical direction) except for Direction 6. Overestimations of position in the z-axis may be caused by overestimations of force.

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