Research On Angle Measurement Error Compensation And New Structure Of Circular Grating Angle Encoder

The circular grating angle encoder is a kind of precision angular displacement sensor.It has the advantages of high accuracy,high reliability,high cost performance,simple structure,small size,easy installation,maintenance.It is widely used in CNC machine tools,robots,articulated coordinate measuring machines,theodolite,radar and other precision equipment.With the continuous development of precision measurement technology,the angle measurement accuracy of the circular grating angle encoder is increasing day by day.Therefore,this thesis conducts an in-depth study on how to improve the angle measurement accuracy of the circular grating angle encoder.The main research contents of this thesis include:Firstly,According to the source of the angle error of the existing circular grating angle encoder,the error of encoder angle measurement is analyzed,and focuses on the long period error of the encoder,and summarizes the long period error distribution characteristics of the encoder.Then the long period error model of the encoder is established by Fourier transform algorithm combined with Fourier expansion.And the particle swarm parameter identification algorithm based on adaptive inertia weight is used for paramleter identification.Finally,the compensation of the long period error of the encoder can be realized.The simulation results show that the compensation method has obvious compensation effect on the long period error of the encoder.Secondly,this thesis analyzes the subdivision principle of the circular grating angle encoder,and uses the tangent subdivision technique to carry out electronic subdivision,so as to deduces the subdivision error calculation formula.And this thesis analyzes the influence of each quality error components of the photoelectric signal on the subdivision error through the simulation software.Then the subdivision error characteristics are analyzed and the encoder subdivision error model is established,and the encoder subdivision error is compensated.In addition,the separation method of the quality errors of photoelectric signals is proposed to separate the error components,and then the subdivision error separation is realized.Then the compensation results before and after the subdivision error separation are compared by simulation analysis.The simulation results verify the subdivision error separation.The feasibility and superiority of compensation.Thirdly,this thesis proposes an indexing circular grating angle encoder,which adds the indexing structure to the current encoder structure,and at the expense of part of the measurement space,the accuracy of the encoder's limited position angle measurement is improved.The structure of the indexing circular grating angle encoder is designed,then the error analysis is carried out according to the working principle of the encoder,and the structure of the indexing circular grating angle encoder is processed.And the experimental platform for measuring the angular error is built,and the angular error detection experiments is carried out by auto-collimator combined with positive polyhedral prism and other instruments.The experimental results verify the superiority of the indexing circular grating angle encoder proposed in this thesis.