Research On High-speed Banknote Thickness Measurement System Based On Beam Displacement Measurement

The paper currency thickness measurement technology is the key technology to verify the authenticity of the cash-counting machine and the cash-sorting machine.At present,banknote cash-counting machines and cash-sorting machines used by domestic banks have the function of measuring paper currency thickness.However,most domestic banknote cash-counting machines adopt mechanical thickness measuring devices.This thickness measurement system uses eddy current sensors to detect paper currency.The mechanical mechanism magnified the tiny thickness signal of paper currency.The result is that the noise caused by the mechanical mechanism affects the accuracy of thickness measurement.In order to solve the error caused by the thickness measuring mechanism,the mechanical structure of the thickness measuring system is optimized.In this paper,the relationship between thickness transfer of the thickness measuring mechanism of the machine is analyzed,and the key component of the thickness measurement error is studied by the modeling simulation and the observation of the high-speed camera.The range of error is given,which provides reference for the next research on optimization mechanism.This article mainly carries on the thorough research to the following aspects:1.Analysis and Research on thickness transfer relationship of paper currency in mechanical thickness measuring system.In order to study the noise caused by mechanical structure in the course of clearing money,we need to know more about the working conditions of each moving part in the mechanical structure.Therefore,according to the process of paper currency detection,the working parts of various parts of the thickness measuring mechanism,namely rocker arm mechanism,shrapnel mechanism and sensor element,are studied in this paper.They are calculated theoretically by mathematical models.The mechanical thickness measuring mechanism provided by the test platform of the cash-sorting machine is used to carry outthe experiment.Mapping displacement,velocity and acceleration information of key components.The wave pattern of important parameters is plotted to analyze the movement process.2.Simulation analysis of deflection variation of beam based on Matlab.In order to study the bending deformation of the key parts of the mechanical structure that affects the thickness measurement,the mathematical model of the shrapnel structure is needed for simulation analysis.Therefore,based on the elementary beam theory,the shrapnel structure is used as a cantilever beam for deflection analysis.In this paper,the formula for calculating the deflection of the beam is introduced.The static Matlab simulation analysis of the deflection of cantilever beam in the process of money entry is carried out.The deflection formula is used as the mathematical model,and the force situation of the piece of bullet is used as the model input,and the deflection of the cantilever beam is output at all times,and the simulation results are drawn.The results can be compared with the actual observations,and the purpose of the error range can be explained.3.The mechanical structure observation of thickness measurement based on high-speed camera.In order to quantitatively study the transmission relationship of thickness measuring machine structure in banknote passing process.To ensure that the thickness of paper currency is transferred to the sensor,the error range of each part needs a high precision image observation instrument to observe in real time.Therefore,on the basis of the theoretical calculation,this paper introduces the high-speed camera to observe the motion of the part of the theoretical calculation,uses the TEMA software to analyze the image pixels,and also collects the information of the displacement,velocity and acceleration of the parts of the thickness measuring mechanism,and obtains the high precision and high speed observation purpose.The interframe reference and theoretical calculation value are compared and analyzed.It is concluded that the range of error is as follows: The maximum error is 0.036 mm,and the maximum relative error reaches 0.31.Through the above research,the paper analyses the paper currency thickness measuring system designed by the eddy current sensor,grasps the movement changes of the parts ofthe thickness measuring mechanism in the process of banknote passing,and gets the range of the error of the key parts,and introduces the vibration model of the bullet to provide the reference basis for the next step of optimizing the mechanical structure of the thickness measurement.