The thesis contains the development of a system including 6 sensor devices, corresponding to the number of players on the volleyball court on one team during volleyball, that send data, containing the number of jumps and their heights, to an application that displays it in real time.
Sensor devices contain an IMU device, a battery, and a microcontroller with a WiFi module for wireless communication with the application on the computer. There are jump recognition and jump duration algorithms implemented on the microcontrollers based on the characteristics of absolute acceleration with respect to time, which is measured by the IMU device. The data from the recognized jumps is then sent to the target computer with UDP packets.
The computer application receives the data, parses it, and then displays it on the screen. It also saves it to external TDMS files. The data is displayed with a simple graphical interface, which shows the number of jumps, their heights, and their averages within the time frames of a match, a set, and a point. The data is saved for each set, and the saved TDMS files can be opened with Excel and serve as a match report.
The verification of the algorithm for determining jump heights, was conducted with two referential systems. The comparison with the optical system Qualisys, where standing jumps and jumps with simulated volleyball hits were performed, showed the differences in heights calculated from the durations of jumps between -14,47 mm and 23,08 mm. The comparison with force plates, where counter movement jumps and squat jumps were performed, showed differences between -23,08 mm and 37,25 mm.
Real-world testing has shown that for the system to be used in practice, the algorithm for jump recognition must be improved considerably. After a minor adjustment, the video analysis determined that the system correctly detected 143 jumps, incorrectly detected 57 jumps, and did not detect 47 jumps.
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