Implementation Of FPGA-based Active Optical Micro-displacement Sensor Filtering Method

The LAMOST telescope in my country adopts the world's leading active optics technology and combines the splicing mirror technology with the thin mirror technology,breaking through the bottleneck that traditional astronomical instruments cannot take into account the large aperture and wide field of view at the same time.This unique mobile splicing mirror has strict requirements for the various indicators of the displacement sensor.In order to optimize the measurement accuracy of this type of sensor,this paper focuses on the filtering method of the sensor's micro-displacement signal,and designs a complete micro-displacement signal filtering system.This article first studies the noise characteristics of the micro-displacement signal,and according to the noise spectrum characteristics and measurement accuracy indicators,formulates the design of the sensor signal filtering system.Subsequently,several classic digital filtering algorithms in the scheme were simulated and analyzed,and a two-channel digital filtering algorithm combining improved four-entry wavelet combined with LMS adaptive filtering was proposed.This algorithm not only retains the advantages of wavelet transform multi-scale analysis,but also improves its denoising ability for low-frequency signals.After completing the algorithm design,the micro-displacement sensor signal filtering system is implemented based on the ZYNQ-7000 hardware platform.The system has functions such as A/D conversion,digital filtering,signal transmission,data storage and image display.Finally,a signal filtering experiment is designed to verify the integrity of the system function.Through comparative analysis of experimental data,it is proved that the signal filtering system designed in this paper can effectively improve the signal-to-noise ratio of the displacement signal,thereby improving the measurement accuracy of the micro-displacement sensor.It has certain application significance for the research of the displacement sensor between the splicing mirrors of large astronomical telescopes.