Estimation of Foot Position Using an Inertial Measurement Unit

FRANCISCO, JOSÉ; EUGENIA SOLEDAD MUÑOZ LARROSA; CAMILA DURÉ; PAOLA CATALFAMO FORMENTO; MAURICIO RIVERA

IFMBE PROCEEDINGS

Springer

Año: 2023

1680-0737

Abstract. Currently, the assessment of spatiotemporal parameters of gait is per-formed in calibrated laboratories using optoelectronic cameras, limiting its ap-plicability in clinical and natural environments. Therefore, the use of wearable de-vices as an alternative has been explored, and in this case, a commercial IMU is employed.The designed device utilizes the BNO085 IMU to obtain linear acceleration and orientation data. An ESP32 microcontroller is responsible for communication with the IMU, writes to the SD card, and power management. The device hard-ware is implemented on a custom PCB and housed in a 3D-printed enclosure. As for the firmware, a program in C++ and C is used, along with Arduino libraries, for IMU handling and writing to the SD card. The obtained data is processed us-ing a MATLAB script, which detects gait events such as foot-off and foot-strike, rotates acceleration into the global frame, and performs numerical double integra-tion of acceleration to obtain estimated position.Tests were conducted using the device on a healthy subject during everyday activities for 15 minutes. Acceleration curves, foot inclination angles, velocity, and estimated position were obtained. The device demonstrated compliance with requirements for autonomy, performance, and ergonomics, with results consistent with existing literature. Conclusion: a wearable device based on an IMU was successfully developed to estimate the trajectory of the human foot during every-day activities, showing potential for application in clinical and rehabilitation stud-ies.