Gait Cycle Ground Reaction Force Measurement Using Piezoelectric Sensor Attached to Shoe-Insole System

Abstract

This study presents a wearable system that mainly consisted of piezoelectric sensors, filter circuit and data logger in order to measure the vertical ground reaction force (VGRF) and study its profile. The proposed system establishes base information to improve the portable gait analysis systems and make them easier in use also to be able to get more outdoor data. The experiments were done by a young healthy person without physical disabilities or nervous disorders and the experimental protocol was explained to the participant before the performing. The experiment involved the walking with self-selected speed along 15 meter track of paved ground. The system was set on (200 Hertz) sampling rate in order to achieve the required data resolution. The produced information was about the events of the gait cycle (Heel-Strike, Stance, Heel-Off and Swing) and their durations also for the VGRF profile of each step and stride which compared with the VGRF profile of force plate. The results of VGRF of sensorinsole system clarified a high similarity with the VGRF produced by force plate system. Despite the system having many features, there are some limitations which can be avoided after improving the system.

Piezoelectric Fixing Direction effect on GRF test results in Wearable Shoe-Insole System

“…And it would not be obvious in the sensor which was in perpendicular direction to the foot midline. On the other hand, the sensor in perpendicular direction to the foot midline senses the interface pressure clearly when compare its result to the data of same subject walking conditions at the force plate as shown in figure 6 [21,22]. The measured GRF with the force plate shows that the standard (M -shape) profile for the GRF, as the data from figure 6 represent the summation of the GRF from all the local sensors in the force plate under the foot print area.…”

“…This charging capability were sufficient to run the experiment for several hours to accomplish the required data collection protocols. In the end the collected data were stored and processed in a PC computer after transmitting through WiFi connection, the data then analysed to extract the gait cycle measurement [21,22].…”

“…The collected voltage data represent the strain rate values at any time [25,26]. The strain value can be found by numerally integrated the collected data with respect to time to find the strain value [21,22]. The founded strain values can be considered as interface pressure, shoe-insole strain, GRF or any other value using the required calibration and coefficients.…”

“…Piezoelectric sensors also used by the researcher in earlier researches to measure the GRF in wide range of daily activities [21,22]. Piezoelectric sensor produces voltage signal when any deformation was applied on them.…”

“…Attached sensors to shoe insole a) in longitudinal direction to the foot midline axis, b) in perpendicular direction to the foot midline axis[21] …”