A low cost sensing system for foot stress recovering on a Freeman platform

This paper highlights the design of a low cost sensing system for the study of foot reaction stress recovering. For instance, measurements are made on Freeman platform for ankle rehabilitation sessions. The system is based on the design of a sensing element and to set it onto a flexible material as a foot shape. The sensor element is based on a Hall Effect device coupled with a magnet in a typical elastic polymer material. The sensors are mounted on a printed circuit board and recovered with a hard polymer layer in order to obtain a uniform distribution of strains. The output signal of each sensing element is carried out to an instrumentation amplifier for adjusting the level of signals and settings. First calibration was performed for the study of the polymer material and then for the mounted sensor element in order to show the feasibility of such stress sensing. After calibration procedure, a dynamic measurement in real environment has been carried out with the instrument bonded onto a Freeman platform.