Estimation of Ground Reaction Force Using Carbon Insoles with Piezoelectric Film Sensors and Force Sensing Resistors

Insole-attached force sensing resistors (FSRs) have been used as an alternative to force plates to estimate ground reaction force (GRF) during gait. Since the FSRs have a narrow sensing area and cannot measure force in the mediolateral and anteroposterior directions, it has been challenging to estimate three components of GRF with high accuracy. This paper reports on a gait measurement system using carbon insoles with attached piezoelectric film sensors and FSRs, and the estimation of three components of GRF using the system. Outputs of piezoelectric film sensors reflect the force that deforms the carbon insole in the mediolateral and anteroposterior directions. Using support vector regression (SVR) models trained with the piezoelectric film sensor and FSR data, the estimation accuracy of the three components of GRF was improved.