Step Length Measurement Through Signal Power Analysis and Accelerometer Device: A Laboratory Comparison

The monitoring and analysis of kinetic and kinematic parameters integrated into sports disciplines such as race walking can provide valuable information for developing personalized training programs and evaluating technique execution. In this study, we developed two systems for measuring step length based on microcontrollers ESP32. The first system is based on measuring the received signal strength between two antennas, while the second relies on inertial sensors (MPU-9250). Both systems were tested in a laboratory setting using a treadmill and video recording to assess their accuracy. The results showed that the system based on signal strength measurement exhibited low precision at distances within a range of a few centimetres. On the other hand, the inertial sensor-based system demonstrated higher accuracy when compared to video recordings. Although the measurements differed statistically between these two methods (p-value = 0.001), the proposed inertial system recorded a step length of 65 (61-69) cm, while the video recordings measured 67 (64-70) cm. The error distribution analysis showed that 39% of measurements had an error of 3.2 cm, 32% had an error of 7.5 cm, and 29% had an error not exceeding 12 cm. The proposed system shows potential for step length quantification using the MPU-9250 sensor; however, further testing is required to reduce the measurement errors.