Research On Plantar Pressure Measurement System Based On PVDF Piezoelectric Film

With the continuous improvement of living standard and technology, the demand for sports fitness is more and more intense. And the body's movement is the process which the foot constantly contact with the ground. Because of its own weight when the foot contact with the ground will produce plantar pressure. The distribution of plantar pressure and pressure will change accordingly when the foot is injured or the motion state changes. Therefore, the research on the plantar pressure distribution has certain scientific significance and application value for clinical medical diagnosis,physical training and other fields. The main research tasks are as follows:(1) In this paper, the PVDF piezoelectric film sensor with easy processing, soft,good toughness and other specialties is used as the acquisition component of the plantar pressure. Based on its piezoelectric characteristics, we develop the circuit board for single plantar pressure measurement, the circuit board is divided into two parts:data acquisition and data communication. Data collection mainly consists of a charge amplifier circuit,a filter circuit,a circuit for adjusting the output and other circuits; Data communication mainly consists of ATmega16 single-chip micropmputer minimum system, wireless data transmission module, serial communications circuit and other circuits. Based on the circuit board for single plantar pressure measurement, we develop a corresponding eight way parallel plantar pressure measurement system. The eight PVDF piezoelectric film sensors are arranged according to the plantar anatomical region.(2) The signal acquisition and conversion of eight PVDF piezoelectric film sensors, wireless data transmission, serial communication and other functions are achieved through the C programming language. In this paper,the software development process of SCM is described in detail, and some key codes are given.Configuring the data transmission rate of wireless data transmission module is set by the YL-100IL communications software,data reception and storage are achieved by serial debugging assistant. And the measured data are imported into MATLAB for data processing.(3) Based on the developed plantar pressure measurement system, the static calibration of PVDF piezoelectric film sensor was developed. Thereinto, the static calibration is carried out under three conditions: K=10, K=25 and K=76, K is the system gain. And the static calibration curve and accuracy analysis of three conditions are given.(4) To design the plantar pressure distribution experiment, the whole experiment was divided into two parts: gait movement experiment and static standing experiment.Gait motion experiment is divided into three groups: barefoot walking experiment,insoles barefoot walking experiments and sports shoes barefoot walking experiment.These three conditions were studied on plantar pressure distribution curves; The distribution of plantar pressure in the single or double feet standing is given by the static standing experiment. Through the analysis of the experimental data, the results show that the data is in accord with the actual condition of the plantar pressure distribution which has achieved the expected design requirements. Practice has proved that the plantar pressure measurement system is feasible.