Design And Implementation Of Multi-channel High-precision Data Acquisition System In Rotating Environment

With the continuous progress of science and technology,rotating machinery and equipment is developing towards the direction of high-speed and complexity,which has been widely used in industrial production,aerospace,agricultural operation and other fields.However,the high-speed and complex rotating machinery will inevitably produce strong noise,which will lead to the worse operating environment of the data acquisition system.How to obtain high-precision sampling data in strong noise environment is of great significance to the monitoring of rotating machinery.Therefore,this paper focuses on data acquisition technology,and carries out the following research:1)According to the system structure and operation environment,the noise and distribution of the system are analyzed,and the corresponding noise modeling work is completed.By analyzing the signal characteristics of the noise source and its propagation path,the hardware circuit and FPGA logic circuit are given respectively to suppress the noise.According to the distribution of the noise,combined with the design requirements,the overall design scheme of the system is proposed.2)In order to achieve high-precision data collection,this study starts from two aspects: hardware circuit design and FPGA logic function design,and completes the design of the main functional modules of the system on the basis of the overall design of the system.In terms of hardware circuit design,a two-stage instrumentation amplifier is used to design a low-noise amplifier circuit;a high-precision operational amplifier is used to design an antialiasing filter circuit up to a frequency of 20 kHz;a high-resolution,low-power and low-noise digital analog is used The converter has designed a high-precision sampling circuit,and designing the power supply using an EMI filter and a low ripple,low noise power chip.In the logic function design of FPGA,in the case of relatively small resource consumption,a serial distribute low-pass filter and an improving distribute filter are designed respectively to realize frequency division filtering processing on the convert signal.In addition,in order to further enhance the completeness of the high-precision data acquisition system,a TCP / IP transmission circuit and eMMC data storage circuit are designed to ensure the reliability of data interaction.3)A high-precision data acquisition system with 128 channels synchronous data acquisition function and the highest sampling rate of 200 kHz is developed.The experimental platform is set up,and the main modules of the system are verified,the system noise suppression function analysis and the system index completion analysis are completed.The data acquisition test shows that all indexes of the data acquisition system in the rotating environment meet the design requirements of the scheme.That is,CMRR ? 80 dB,dynamic gain precision SFDR?65 dbc,gain precision GA?0.1%,acquisition precision SFR?0.1%.