Table 4.1 presents a summary of the studies that assessed the validity and reliability of LPSs.
Table 4.1 Validity and reliability results published in the scientific literature related to tracking devices with LPS technology
Company Device Alg. Anch SF Trials Assessment Criterion Variable
Catapult Clearsky T6
TDOA/AOA 18 10
Hz
Running with change of direction.
Jog/maximal acceleration 12 m linear course
Validity VICOM Distance
Mean/pea speed Accelerati
Linear course sprint and deceleration to stop
Diagonal movement with 75° turn Linear course with 90° turn and
deceleration to stop
Zig-zag (turns of 60°)
Validity Infra-red
camera system
Distance
Instantaneous speed
MEAN = > 3 Nothing But
Net NBN23 – 12 9 Hz
17 Hz 33 Hz 50 Hz
3 walking 4–6 running 3 sprint
Validity Timing gates Distance
Running t
Reliability Inter-unit Walking Running Sprinting WASP
wireless – Least
squares 12 10
Hz Outdoor linear Validity Tape
measurement Positioning
Indoor non-linear linear Outdoor linear Indoor linear KINEXON
ONE
Version 1.0.
– 12 18
Hz 20 Hz
Soccer specific circuits
Validity Athletics track Distance (18
Distance (20 Sprint (18 H
Company Device Alg. Anch SF Trials Assessment Criterion Variable Sprint (20 H Reliability Intra-unit Distance (18 Distance (20 Sprint (18 H Sprint (20 H Ubisense Series 7000 TDOA/
AOA
4 Hz Runs in the center of the playing field and perimeters, SSG (5 vs. 5)
Validity Trundle wheel Distance dur courses SSG
RealTrack Systems
WIMU PRO
TDOA 8 33
Hz
Over lines of the court
Validity Tape measure Distance
Reliability Inter-unit CV = < 1%
Test-retest Inter-subject WIMU
PRO
TDOA 6 18
Hz
3 Circuits with linear, circular, and zig-zag courses
Validity Timing gates Tape measure
Distance Velocity
Reliability Inter-unit Distance Intra-unit Distance
Five courses:
field perimeter, halfway line, center circle, penalty area perimeter, semicircle penalty area, and small- sided game
Validity Tape measure X coordinate Y coordin
Reliability Inter-unit Occupied are Five courses:
static position, field
perimeter, perimeter marking of court, halfway line, center circle.
Validity Timing-gates X coordinate Y coordin
Company Device Alg. Anch SF Trials Assessment Criterion Variable Reliability Inter unit X coordinate
Y coordin
– Lpm04.59 TDOA 19 45
Hz
Distance/speed Walking and sprinting Straight (500), 45° turn (1000), 90°
turn (1000), combined (2500)
Validity Tape measure
and timing gate
Distance Walking straight Walking 4 turn Walking 9 turn Combined Sprint stra Sprint 45°
Sprint 90°
Combined Speed Walking straight Walking 4 turn Walking 9 turn Combined Sprint stra Sprint 45°
Sprint 90°
Combined
TDOA 11 45
Hz
Linear movement
= Low speed (25 m);
medium speed (25 m); high speed (25 m);
Acceleration, stop (at 12.5 m), acceleration;
Acceleration, stop (at 12.5 m), turn and acceleration.
Validity VICOM Distance
Distance a low speed Distance a run-stop-r
TOF 12 45
Hz
Walking, jogging, low, moderate, high-speed, and sprinting = Straight (500), 45° turn (1000), 90°
turn (1000) and SSG (3 vs 3)
Validity LAVEG Distance
X coordin Y coordin
Company Device Alg. Anch SF Trials Assessment Criterion Variable Inmotio Version
05.30 R
– 11 45
Hz Jog =
submaximal and maximal:
Straight, 180°
change of direction, 90°
change of direction
Validity VICOM Distance/spe
with 180°
Accelerati deceleratio Peak acceleratio Peak deceleratio Version
2.6.9.545 – 11 45
Hz Soccer specific
courses Interchangeability Timing gates Distance Distance a high inten Accelerati
Version 3.7.1.153
– 11 45
Hz
Soccer specific courses
Validity VICOM Position
Instantane speed Instantane acceleratio SSG
Note: CV: Coefficient of variation; TEM: Typical error of measurement; ICC: Intraclass correlation coefficient; LPM: Local position measurement; MAE: Mean absolute error; LPS: Local positioning system; SSG: Small-sided games; RMSE: Root mean square error; TDOA: Time difference of arrival; TEE: Typical error of estimate; TOA: Time of arrival; UWB: Ultra-wide-band;
WASP: Wireless ad hoc system for positioning.
EPTS Performance Test Report
The FIFA Quality Program sets an industry standard of quality and reliability for products, technologies, and surfaces that have a direct impact on football (http://quality.fifa.com/es/standards/).
In the list made available on November 21, 2020 at https://football-technology. fifa.com/en/media-tiles/fifa- quality-performance-reports-for-epts/, two LPSs were available and certified: (i) Realtrack Systems – WIMU PRO and (ii) Catapult – Vector. The summary of the performance test report can be found in Table 4.2.
Table 4.2 Ratings by FIFA velocity band for the two LPS subjected to EPTS performance test report (January 16, 2020) System 0–7 km/h 7–15 km/h 15–20 km/h 20–25 km/h >25 km/h
Velocity RMSD (m/s) RS-WP WaIS AIS WaIS WaIS N/A
C-V WaIS WaIS AIS AIS WaIS
Position RMSD (m) RS-WP WaIS AIS IS BIW N/A
C-V WaIS WaIS WaIS WaIS WaIS
Note: RMSD: Root mean square difference; RS-WP: Realtrack systems – WIMU PRO; C-V: Catapult – Vector; WaIS: Well-above industry standard; AIS: Above industry standard; IS: Industry standard; BIS: Below industry standard; WbIS: Well-below industry standard; N/A: no data reported.
Manufacturer Characteristics
Table 4.3 presents the technical specifications of the LPSs commonly used by team sports and based on the available information provided by the manufactures.
Table 4.3 Characteristics of LPSs of different manufacturers Sampling
rate (Hz)N°
anchorsGPS
integratedTriaxial
accelerometerTriaxial gyroscope Triaxial
magnetometerBattery life (hrs)
HR data
available Threshold for each player?
CATAPULT ClearSky T6
10 10–20 No 1kHz 4000
degrees/second at 100 Hz
100 Hz 5 Compatible
with polar sensors
Yes
CATAPULT Vector
10 24 Yes 1kHz 2000
degrees/second at 100 Hz
100Hz 6 Compatible
with polar sensors
Yes
Kinexon 10–
1000
6–16 No 200 Hz 200 Hz 20 Hz 4 Compatible
with third- party sensors
Yes
REALTRACK
Wimu Pro < 55 6–12 Yes 4 sensors <
1000 Hz 3 sensors < 1000
Hz 160 Hz 5 Compatible
with third- party sensors
Yes
App: application; HR: heart rate; Hz: hertz; hrs: hours; UWB: ultra-wideband.
Lessons Learned and Concluding Remarks
The LPS is a valid and reliable technology that can be used to determine a player’s position during matches in different scenarios (open-field and indoor). The advantage of being used in different scenarios – and the fact that it is possibly more accurate and precise than GPSs – makes the LPS an interesting choice for those who can afford the technology.
The few LPS solutions certified by FIFA exhibited high standards. Most of the LPSs in the sports market are based on UWB. The accuracy revealed by most of the solutions makes it possible not only to properly quantify a player’s external load but also to advance the implementation of tactical metrics that determine a team’s dynamics based on players’ positions.