Development And Application Of Flexible Three-Dimensional Force Sensor Based On Polyaniline/polyvinyl Alcohol Hydrogel

Compared with traditional sensors,the flexible three-dimensional force sensor has the advantages of good plasticity and miniaturization,which can fit the substrate arbitrarily under different complex working environments and accurately measure the multi-dimensional force information.In addition,as the main tool of information collection,flexible three-dimensional force sensors are also widely used in intelligent robots,electronic skin,health and medical testing and industrial manufacturing.The base material of flexible three-dimensional force sensor is the key to achieve high flexibility,and polyaniline/polyvinyl alcohol（PANI/PVA）hydrogel is one of the research hotspots of new flexible base material because of its excellent mechanical properties and sensing performance.Therefore,this paper studies the mechanical properties and sensing properties of PANI/PVA hydrogel from the macroscopic and microscopic perspectives.A sandwich flexible three-dimensional force sensor was designed and fabricated from the pressure-sensitive material.First,the choice of composite material system is studied,the substrate material,conductive filler,protic acid and initiator are studied,and the optimal material is selected.The results show that PANI/PVA hydrogels have excellent mechanical properties,high sensitivity（GF≈1.35）,high conductivity（10.8S/m）,stable repeatability,and are suitable for flexible three-dimensional force sensor pressure-sensitive material.Secondly,the conductive mechanism of PANI/PVA hydrogel is analyzed and the structure of flexible three-dimensional force sensor is designed.A sandwich structure is chosen.It is composed of raised stress loading layer,upper FPCB board,pressure sensitive material PANI/PVA hydrogel and lower FPCB board respectively.The force analysis of the structure is carried out theoretically,and the analysis results show that the structure has the ability to distinguish and decompose three-dimensional forces,and the structure is verified by simulation.And a flexible three-dimensional force sensor is prepared.Finally,a calibration experiment system is set up to carry out static calibration experiment on the flexible three-dimensional force sensor.The calibration system consists of a three-dimensional force loading platform,a standard three-dimensional force sensor with a resolution of 0.02N and a high-precision multimeter.The flexible three-dimensional force sensors are calibrated and synchronously collected.The BP neural network（SSA-BP）optimized by sparrow search algorithm is used to decouple the calibration data.The decoupling results show that the SSA-BP neural network achieves the best position after 19 iterations,and the loss error is9.3×10^-6 N.Compared with the single BP neural network,the SSA-BP neural network has better convergence speed and accuracy.