Monitoring and analysis of plantar pressure map and foot motions using a wearable sensing system

H. K. Abdul-Ameer, Z. Ali, D. Falah, L. Issa, A. H. Al-Timemy

Abstract: In this paper, a plantar pressure and foot kinematics measurement system is proposed for detecting normal and abnormal gait. A sensorized insole was fabricated using five force resistive sensors and was set in a thin layer of Fablon adhesive film. An inertial measurement unit (IMU) is located at end of the distal phalanx of the second toe to read acceleration and gyroscope data in three axes. The insole and inertial unit are connected to a microcontroller which is strapped to the subject’s leg. The data can be transmitted to a host computer via a Wi-Fi module for processing. The system was evaluated with 11 subjects, 10 normal and one has a plate on his tibia. The insole data are normalized using scaling feature method where peak pressure values are obtained and utilized to identify normal gait cycle. The acceleration and gyroscope data are processed with moving average method and kernel density estimation to validate the collected data from the developed sensing system. The sensing system has shown beneficial results in acquiring and analysing of the plantar pressure and foot motions. In addition, the importance of normalized plantar pressure and foot motions in identifying gait abnormalities are highlighted, in which these values have the potential to be used as classifying features. Using kernel density estimation shows the viability of recognizing additional features that can be utilized in detecting abnormalities in the gait.

Series on Biomechanics, Vol.35 No.3 (2021), 46-56

Keywords: foot motions; kernel density estimation; Plantar presser measurement; smart insole

Date published: 2021-10-26