Design And Research Of Flexible Three-dimensional Force Capacitive Tactile Sensor

With the wide application of intelligent robots in production and life,high-performance tactile sensor that can sense external information have gradually become the focus of research,and a variety of types of tactile sensors have also emerged.Among them,the principle and structure of capacitive tactile sensor is relatively simple,and it has good frequency response,high sensitivity and a wide dynamic range,so it has become a hot research type of tactile sensor.A flexible capacitive tactile sensor which can detect three-dimensional force is designed by using a PDMS(polydimethylsiloxane)sponge with porous micro-structure as the dielectric layer,in order to overcome the shortage of sensitivity and small measurement range of capacitive tactile sensor in three-dimensional force detection.The sensor has high detection sensitivity in a large range,and is easy to fabricate,low cost and conducive to largescale production.Firstly,based on the basic formula of parallel plate capacitance,the relationship between sensitivity of capacitive tactile sensor and dielectric layer is deduced,and the force distortion of flexible capacitive plate is analyzed and calculated by potential theory.The mechanical properties of porous micro-structure sponge elastomer are analyzed by finite element software,and the output characteristics of two capacitive tactile sensors are compared.The results show that the porous micro-structure tactile sensor has higher detection sensitivity under the same pressure.On this basis,the effect of pore density and thickness of dielectric layer on the detection sensitivity of the tactile sensor is discussed.A flexible three-dimensional force capacitive tactile sensor based on porous microstructure dielectric layer is designed.The design idea and material selection of each component are elaborated in detail,the principle of three-dimensional force detection is analyzed,and the designed sensor is simulated by finite element,and the deformation and capacitance change trend of the sensor under three-dimensional force are obtained.An experimental platform is set up,and the sensor unit is fabricated,and the static performance and three-dimensional force loading experiments of the sensor unit is carried out.The results of the prototype test show that the sensor can detect the three-dimensional force with good hysteresis,repeatability and high sensitivity.Combined with the experimental data,the threedimensional force decoupling of the sensor is completed.Finally,the array design is carried out using the resulting sensor unit.In order to improve the flexibility and measurement accuracy of the tactile sensor array,the structure of the electrode array is improved and optimized,and two design schemes of the electrode lead-out line are presented.Based on the way of row and column scanning,the hardware circuit of the tactile sensor array acquisition system is designed,which has a high scan frequency and can quickly collect and transmit capacitance data to the host computer.