A Tactile Force Sensor Array Based On PVDF

Compared with other types of piezoelectric materials,polyvinylidene fluoride(PVDF)film has a larger frequency response range,better ductility,and excellent sensitivity under the same conditions,so it is more suitable for making contact force sensor in cantacting with human body.This paper mainly studies and designs a contact force sensor array based on PVDF.The theoretical voltage output expression of each array point is obtained,the upper and lower substrate materials are optimized,the static and dynamic characteristics of the sensor array are characterized by experiments,and it is proved that the sensor can accurately identify the palm contact force.The specific research contents are as follows:(1)Theoretical calculation and simulation of PVDF force sensor array.Based on piezoelectric theory,the relationship of output voltage and input pressure is deducted,which is the functional formula of each array point sensitivity point.By using ANSYS Workbench software,a single array point and multiple array points of the sensor were analyzed by piezoelectric coupling,and the voltage output after finite element analysis was observed and compared with the theoretical value,and the error value was obtained In view of the voltage in the non-forced area,a stress analysis was carried out,and the conclusion was obtained that the voltage output of the non-forced area is related to the stretching mode of the PVDF film.(2)Design and optimization of contact force sensor array based on PVDF.Based on the theoretical calculation,the formula between the theoretical output voltage and the input pressure,and the simulation results of the pressure input of multiple array points are obtained.The theoretical value of the voltage output of each array point after the pressure input is derived through the formula.The relationship among the pressure applied in the force region,the stress in the x-axis direction in the non-force region and the distance between the non-force region and the force region is derived by using the thin film theory.The optimal distance between the sensor array point and the array point is obtained by using the relationship.In ANSYS Workbench,the combination of the upper and lower substrate materials and the thickness of the upper and lower substrate are optimized and analyzed.(3)Performance characterization of PVDF contact force sensor and palm contact force acquisition experiment.According to the design and actual manufacturing process,the PVDF-based contact force sensor array meeting the experimental requirements was obtained.The experimental platform of dynamic and static performance test is built to characterize each array point of the sensor array statically and dynamically,and the sensitivity,nonlinearity and frequency response range of each array point are obtained.Based on the obtained performance parameters,the size and range of the general palm contact force experiment is carried out.The data collected in the experiment can be processed by Python software to get the color contrast diagram of the single point contact force and multi-point contact force output voltage of the palm on the sensor array.The result of the contrast diagram shows that the sensor can accurately identify which array points have voltage output and the size of the voltage output value.The results show that the designed sensor array can recognize the palm shape and contact force to a certain extent.