Research On Flexible Bionic Tactile Sensor Based On Pressure-sensitive Materials

With the rapid development of robot technology,the intelligence of robots is getting higher and higher.They not only help humans to complete many repetitive and boring tasks,but also gradually participate in various production activities.They are widely used in military,aerospace,rehabilitation,medical treatment,industry and other fields.Because of the complexity of robot operation environment,the perception ability of robots to the external environment becomes more and more important,and the perception ability of robots is mainly realized by sensors,so the sensors mounted on robots have become an important issue in today's research.As a kind of contact perception,tactile sense plays an indispensable role in the physical contact with the environment.In tactile sense,the perception of contact force and the recognition of materials of contact objects play an important role in the tasks related to the contact with objects.Accurate recognition of pressure and materials is helpful for robots to complete interactive tasks.However,there are few studies on the simultaneous perception of both.In view of this situation,a bionic flexible tactile sensor was designed and manufactured based on the structure of human fingers by combining the carbon black-porous PDMS piezo-resistive material and PVDF piezoelectric film material,which can simultaneously sense positive pressure and classify and recognize the material of objects.Using the universal testing machine and the linear module as the experimental platform,the practical application ability of the sensor is verified.The main research contents of this paper are:(1)Selection and testing of flexible materials and structural design of sensors:according to the actual application of sensors,PDMS material is selected from a variety of flexible materials as the main material of sensors to achieve the goal of flexibility,and its mechanical properties are tested.Based on human finger structure,a sensor structure consisting of "phalanx","sensor unit" and "skin" was designed.(2)The preparation of flexible piezo-resistive materials: to reduce the elastic modulus of materials and simplify the process of filling the conductive particles,spongy porous PDMS material with low elastic modulus was produced by "particle leaching method" with PDMS and sugar cube.Carbon black-porous PDMS material with piezo-resistive effect was prepared by using porous PDMS material and carbon black particles through "blending coating method" and its elastic modulus and piezo-resistive properties were tested separately.Finally,it is encapsulated as a pressure sensing unit.(3)Fabrication of piezoelectric sensing elements and structural optimization of sensors:piezoelectric films are made into piezoelectric sensing units that can be used for vibration signal perception through cutting,non-metallic edge modification,and lead drawing,etc.and their ability to perceive vibration signals is tested.Then,the finite element analysis software of Workbench is used to optimize the structure of the sensor,which provides a basis for the shape determination of the sensor.(4)Research on pressure perception and material identification methods: the pressure perception performance of the sensor was tested by the universal testing machine,and the measured object was driven to slide by the linear module.Through the interception,filtering and extraction of characteristic values of vibration signals in the sliding process,the classification algorithm is used to realize the function of material classification and recognition.