Research On Signal Processing And Three-Dimensional Force Detection System Based On PVDF Tactile Sensor

In recent years,the fields of human-computer interaction,wearable electronic devices,and electronic skin have developed rapidly,tactile sensor have attracted attention as the core component.With the expansion of the application field of tactile sensor,higher performance requirements have been put forward,in some application scenarios,tactile sensors are required to have the function of detecting three-dimensional forces.Polyvinylidene fluoride(PVDF)has the advantages of good flexibility,wide frequency response,corrosion resistance,which is one of the main materials of flexible piezoelectric tactile sensors at present.In this paper,a signal processing system for PVDF tactile sensors array and a three-dimensional force sensor with a hemispherical structure which using the PVDF tactile sensors as a sensing element is designed,the system and the sensor constitute a three-dimensional force detection system.The main contents of this paper and results include:1.Designed and fabricated the signal acquisition circuit system of PVDF sensor array,including a charge amplifier module,a multi-channel module,a voltage boost module,MCU with A/D module and a data transmission module.The circuit can simultaneously collect signals of eight channels under the control of the single-chip computer,and transmit data to the upper computer through the serial port.2.A Windows form application software is designed with Winform.The software is responsible for receiving data transmitted by the circuit,processing and displaying the data on the software interface in real time.Including the display of the data waveform of each channel,the display of the force distribution on the PVDF sensor array,and the display of three-dimensional force information.The signal processing system is composed of circuits and software,the charge range that can be collected by the system is-2.5 n C to 2.5 n C,and the accuracy is about 5 p C.The system can process the signals of eight channels at the same time,the data processing speed of each channel is 200 / s.The system can completely restore the signal waveform below 10 Hz,and is suitable for application scenarios where the signal frequency is low,such as hand grasp recognition,plantar pressure distribution,etc.3.Two sizes of three-dimensional force sensor with hemispherical structure is designed,the hemisphere diameters of the two sensors were 1.8 cm and 3 cm,respectively.the algorithm of three-dimensional force is deduced and integrated with signal processing systems.The parameters of the algorithm are obtained by calibrating the three-dimensional force sensor.Test the three-dimensional force detection system consisting of the three-dimensional force sensor and the signal processing system.The results show that the detection system composed of a three-dimensional force sensor with a hemisphere diameter of3 cm is more accurate in identifying external forces,the measurement error range of the system is 7.27% ± 4.35%.The sensitivity to the force in X,Y,Z-axes are 0.216,0.287,0.091V/N,the minimum force changes that can be recognized in X,Y,Z-axes are 0.046,0.035,0.110 N.The system can identify three-dimensional forces between 0 and 15 N.