Research On Structural Design And Sensing Characteristics Of Three-dimensional Capacitive Flexible Tactile Sensor

With the rapid development of artificial intelligence technology,intelligent robots play an increasingly important role in production and daily life.The collection of external information by robots has become an important issue.In the face of complex and diverse work environment,the collection efficiency of visual sensing technology will be greatly reduced.Under this condition,many researchers pay more and more attention to the research of the tactile sensing technology.Tactile sensor as an important means of tactile sensing technology has also been in-depth study.With the development of manufacturing technology and material science,the research on tactile sensors has made great progress in recent years.However,there are still many deficiencies.The main problems are the inability to measure three-dimensional forces,low resolution,low sensitivity and poor repeatability,etc.These defects limit the promotion and application of tactile sensors severely.In order to develop a high-precision,high-resolution and highly-flexible tactile sensor,this paper starts from the sensitive unit of the capacitive tactile sensor.Firstly,the mathematical model of capacitive tactile sensor is built,and the force analysis of the sensor is carried out from the perspective of two-dimensional model and three-dimensional model respectively.Then,the structural design and material selection are compared and analyzed.Finally,the overall design of the three-dimensional capacitive flexible tactile sensor is completed,and the three-dimensional force measurement is realized.The dielectric layer of the capacitive tactile sensor is improved by using cylinder array,truncated pyramid array and pyramid array micro-structure instead of the whole PDMS dielectric layer respectively to improve the sensitivity of the sensor.The force distribution of the sensor under different micro structures,the change of capacitance and sensitivity are studied when the force is applied in the normal direction and shear direction.Finally,the array structure with the largest deformation under the force is determined.The impact of various factors on the sensitivity of the capacitive tactile sensor is analyzed from multiple perspectives.The influence of the change of Young's modulus of PDMS material on the sensitivity of the sensor is studied.Due to the complex and changeable working environment of the tactile sensor,the influence of temperature on the working characteristics of the sensor is further studied when the package stress is considered.In addition,the shear sensitivity is also discussed when the bump layer of the sensor is worn down.The capacitance change of the tactile sensor is very small because of its ultra-thin and miniature characteristics.Under this condition,the capacitance change of the capacitive tactile sensor is transformed into the corresponding voltage signal output by using the dynamic micro-capacitance detection circuit based on AC bridge and the real-time peak detection circuit.