Research On Separation Method Of Moiré Signals Feature Of Turntable Based On Demodulation

The turntable angular measurement system can measure angles precisely and has a very important position in the field of angle measurement.The turntable angular measurement system is widely used in precision manufacturing,medical devices,defense industry and other fields,because it has the advantages of high resolution,large measuring stroke and continuous angle measurement.However,The turntable angular measurement system will be damaged in the course of a long period of use,the reliability and stability of the turntable angular measurement system needs to be ensured by monitoring.Through the investigation of the working condition monitoring methods of the turntable angular measurement system at home and abroad,traditional methods rely on high-precision calibration platforms to complete the monitoring,which is complex and cumbersome.Considering the development trend of efficient and convenient methods for monitoring the working condition of the turntable angular measurement system,this thesis focuses on the correlation between working condition of the turntable angular measurement system and Moirésignals feature,in order to complete the monitoring of the working condition of the turntable angular measurement system without the limitation of the high-precision calibration platform.The main contents include:1)Based on the working principle of the turntable angular measurement system,the principle of generating the Moirésignals feature is described.According to the time-frequency characteristics of the Moirésignals and the signal demodulation principle,the Moirésignals feature are separated from the frequency domain by digital envelope detection.2)The main error sources of the turntable angular measurement system is analyzed,the effect model of eccentricity and inclination are established respectively,and provide a theoretical basis for the main monitoring objects of the working condition of the turntable angular measurement system.3)A high-speed ADC sampling circuit,on-chip memory circuit and data transmission circuit are designed to obtain the Moirésignals and the separation of Moirésignals feature is based on the Field Programmable Gate Array,the Moirésignals feature separation circuit is developed to minimize the resources occupied by digital low-pass filters.4)The validity of the Moirésignals feature separation circuit and the validity of the Moirésignals feature separation method are verified.The validity of the effect model of eccentricity and inclination are verified by experiment,and the theoretical basis is enriched for the main monitoring objects of the working condition of the turntable angular measurement system.The results show that the measured object contains Moirésignals feature,and the 1^stharmonic and 2^ndharmonic characteristics are obvious,but there is no obvious fluctuation of Moirésignals feature when the measured object is working,which proves that the design method of this thesis can efficiently and conveniently complete the monitoring of the working condition of the turntable angular measurement system.