Assessment of the Accuracy and Inter-Unit Agreement of Ultra-Wide Band to Compute Team Positioning in a Basketball Court

Abstract

Local positioning systems have shown high accuracy for measuring the distance covered and the mean velocities and also for time-motion analysis. However, no study has assessed the accuracy and inter-unit agreement of local positioning system [LPS] technology to compute any collective tactical behavior variable. The main aim of the study was to analyze the accuracy of ultra-wideband and calculate inter-device agreement to compute the geometrical center coordinates (i.e., the relative positioning of each team represented in a single point computed considering x and y coordinates of the players). The inter-device geometrical center agreement of the devices when placed in the corners [static] of a basketball court was also assessed. The geometrical center (x, y coordinates) computed by a local positioning system tool, called an inertial measurement unit, was compared to the known geometrical center position in four different court areas: [1] 15x7 m, [2] 15x14 m [3] 15x21 m [4] 15x28 m. In each of the court areas, two different devices were placed on three tripods [60 cm from the floor] in three corners of the perimeter described. The distance of the device to the reference element was calculated every 0.5 s, providing a total of 600 samples. The absolute difference between the geometrical center measured on the ultra-wideband devices and the real geometrical center was less than 0-1.1%, with an absolute difference of 0 to 0.09 m in all the court areas. The difference between the devices when the geometrical center was computed was from 0.14 to 1.36%, with an absolute difference of 0.02 to 0.09 m. The accuracy of the ultra-wide band and inter-device agreement for computing the geometrical center was high (absolute error < 10 cm). These findings may suggest future validation protocols of the ultra-wide band for the assessment of collective tactical variables in team sports under a real match or training conditions.