Real-time detection of reaction forces during gait on a ground equipped with a large force platform

Introduction: In health monitoring and biotelemetry, the real-time recording of ground reaction forces under each foot during gait has a large potential for the automatic detection of abnormal posture, falling prevention, etc. at home or in public places. For this, mounting a large force platform on/in the ground ensures to record data for numerous footsteps while avoiding the step `targeting' problem. Davis and Cavanagh (1993) have proposed a solution using a large force plate but several points of Davis and Cavanagh's method remain unclear and hardly computable. Objective: Develop a method that decomposes left and right GRF profiles from the GRF profile recorded on a single platform. This method aims to include a systematic detection of the single to double stand-phase-instants in order to lead to accurate measurement of the total GRF component in typically developing children. Methods: Six children were asked to walk without targeting their footsteps on a set-up composed of independent force platforms. The total GRF component, independently measured on the different platforms, was numerically summed to obtain the corresponding global total GRF, to which the decomposition method was applied. Then, the validation consisted in comparing the total GRF computed from this decomposition to the independently measured total GRF. Results: The mean relative error between the computed total GRF and the corresponding measured vertical GRF of 36 double stances (6 double stances × 6 children) is equal to 3.8±2.6%. Conclusion: We have implemented an innovative method to assess with accuracy the vertical GRF component under each foot using a unique large force platform. This leads to large perspectives in health monitoring and biotelemetry.