Flexible Three-dimensional Force Tactile Sensor Based On Graphene Aerogel Piezoresistive Effect

In recent years,the fields of intelligent robotics and human-computer interaction have made rapid progress.As the core devices in the above-mentioned fields,tactile sensors also attracted much attention.Some specific application scenarios have put forward the requirement of three-dimensional（3D）force detection for flexible tactile sensors as the application field of tactile sensors continues to expand.The existing flexible 3D force tactile sensors still have space to improve in terms of detection range,sensitivity,reliability,and response time.In view of this,a high-performance flexible 3D force tactile sensor was designed and prepared using graphene aerogel as a sensitive material and a corresponding 3D force signal acquisition system was developed to realize the acquisition and analysis of mechanical signals in this thesis.The main contents and results of the research in this paper include following parts:（1）Design and modelling of a flexible 3D force tactile sensor.Based on the piezoresistive effect of graphene aerogel,a flexible 3D force tactile sensor is proposed and designed,including four parts:flexible bump layer,piezoresistive layer,electrode,and flexible substrate.The mechanical model of the sensor is established,the axial component force is calculated by the deformation of the sensitive unit,and the corresponding working mechanism is elaborated and further validated by finite element simulation analysis.（2）Preparation and testing of flexible 3D force tactile sensors.The active material of graphene aerogel was obtained by step-by-step reduction method.The flexible bump layer and lower substrate were fabricated by light-curing 3D printer combined with template method;and the flexible 3D force tactile sensor was fabricated by layer-by-layer assembly technique.The sensor performance test platform was built to test the detection performance of forward pressure and arbitrary 3D force,respectively.The test results show that the sensor possesses excellent sensing performance,with high pressure sensitivity,the pressure is in the range of 0.3～0.7N,and the sensitivity is 1.138N^-1;fast dynamic response,the response time and recovery time are45.9 ms and 29.8 ms respectively;good stability and reliability under multiple cycles;the sensor can quickly detect the force in any direction in space.（3）Non-linear decoupling of flexible 3D force tactile sensors.The coupling analysis of the flexible 3D force tactile sensor was carried out,and it was concluded that the coupling calculation results of the sensor were affected by the sensor structure,measurement method,and manufacturing assembly accuracy.Therefore,the output signal was disturbed by many external factors.On this basis,BP and GA-BP neural network algorithms are introduced in detail,relevant comparison experiments are conducted,and the optimal 3D force decoupling algorithm is finally selected.（4）Design of a flexible 3D force tactile sensor signal acquisition and decoupling system.A three-dimensional force signal acquisition and the decoupling system are designed,which mainly consists of hardware circuits and upper computer software.According to the structural characteristics of the tactile sensor,the signal acquisition circuit is built by using the principle of voltage division,and the data is uploaded to the PC via USB.Then the upper computer software is written by LabVIEW to realize the communication with STC15microcontroller,processing of sensing signal and multi-mode display,and the 3D force decoupling program is written by combining with GA-BP neural network algorithm.