Validity of a magnet‐based timing system using the magnetometer built into an imu

Abstract

Inertial measurement units (IMUs) represent a technology that is booming in sports right now. The aim of this study was to evaluate the validity of a new application on the use of these wearable sensors, specifically to evaluate a magnet‐based timing system (M‐BTS) for timing short-duration sports actions using the magnetometer built into an IMU in different sporting contexts. Forty‐eight athletes (22.7 ± 3.3 years, 72.2 ± 10.3 kg, 176.9 ± 8.5 cm) and eight skiers (17.4 ± 0.8 years, 176.4 ± 4.9 cm, 67.7 ± 2.0 kg) performed a 60‐m linear sprint running test and a ski slalom, respec-tively. The M‐BTS consisted of placing several magnets along the course in both contexts. The mag-netometer built into the IMU detected the peak‐shaped magnetic field when passing near the magnets at a certain speed. The time between peaks was calculated. The system was validated with photocells. The 95% error intervals for the total times were less than 0.077 s for the running test and 0.050 s for the ski slalom. With the M‐BTS, future studies could select and cut the signals belonging to the other sensors that are integrated in the IMU, such as the accelerometer and the gyroscope.