Where Are the Best Positions of IMU Sensors for HAR? - Approach by a Garment Device with Fine-Grained Grid IMUs -
Akihisa Tsukamoto, Naoto Yoshida, Tomoko Yonezawa, Kenji Mase, Yu Enokibori · 2023
Many IMU-data-based HAR datasets have been proposed. However, integrating the use of those is difficult because each dataset is measured by its unique sensor positions. Thus, we have developed a garment device with 396 IMU sensors placed in a grid with approximately 7 cm spacing to enable the matching of IMU data from various positions and the integrated use of multiple databases. In this paper, the best and most suitable sensor positions for classification were explored with this device for six basic activities and eight daily activities with the expectation of determining the key IMU positions for the integrated dataset and creating standard sensor positions when building a new dataset. The single sensor positions with the highest classification performance in all activities, basic activities, and daily activities were the upper-middle part of the dominant lower arm, the front of the thigh, and the inner wrist of the dominant arm. The position with the highest classification score for daily activities except Writing and Typing was the inner wrist of the dominant arm. The sensor position with the highest classification score for Writing was the upper part of the dominant upper arm, and Typing was the upper-middle part of the non-dominant lower arm. Furthermore, the combination of the four sensors showed the best macro-F1 scores for all activity sets: 0.90 with all activities, 1.00 with basic activities, and 0.83 with daily activities.