Prédiction des forces de réaction au sol lors de la marche avec des capteurs inertiels

Abstract

The public Health Agency of Canada recorded 85170 cases of stroke in 2015 leading to hemiparesis among the affected patients. Spatiotemporal asymmetries are observed in 48 to 60% of the cases. The clinicians rely on some visual observations to assess the loading asymmetry during the rehabilitation process. The impact of this asymmetry during gait on daily life activities is not evaluated. The aim of this study is to estimate the ground reaction forces (GRF) during walking with inertial sensors in healthy subjects. To do so, two inertial sensors placed on the tibia were used for six healthy subjects that were instructed to walk under five walking conditions on an instrumented treadmill working under symmetric and asymmetric modes. The force platforms embedded in the treadmill are the gold standard for the measurement of the GRFs and constituted the kinetic reference. A nonlinear system identification model was used to predict the GRFs based on the inertial sensors data and the benchmark forces obtained from the force platforms. The vertical and the anteroposterior forces were considered for the right and the left legs, simultaneously. The Bland-Altman method was used to evaluate the agreement between the predicted and the measured forces and the precision was assessed by calculating the prediction errors. The results gave a normalized root mean square error of 5.21 and 7.28% at the comfortable speed for the GRFV and GRFAP, respectively. At slow speed of 0.8 m/s, the error was 3.79 and 6.74% for the two forces. At a slower speed of 0.4 m/s, the error obtained was 5.13 and 10.31%, respectively. For the asymmetric mode with an asymmetry ratio of 1/1.5, we report an error of 5.35 and 7.45%, and lastly, for an asymmetry ratio of 1/2, the error reached 6.27 and 8.54%, in the vertical and anteroposterior directions, respectively. The results obtained with our model were comparable with those obtained in the literature with a higher precision compared to previous work. These results show that the inertial sensors might be used to estimate the GRF outside the laboratory by providing an ambulatory mean to predict them. In future work, the developed method can be applied on the data collected among hemiparetic subjects walking inside and outside of the laboratory.

Date	4 Jul 2020
Original language	French
Awarding Institution	École de technologie supérieure
Supervisor	Rachid Aissaoui (Supervisor) & Sylvie Nadeau (Co-supervisor)