Research On Underwater Running Fiber Optic Gyro Monitoring System And Its Error Analysis

In recent years,with the vigorous development of hydropower construction,the main battlefield of domestic water resources strategic development has gradually shifted to the western region with more complex geographical conditions.At present,most of the large-scale hydropower projects under construction and planned to be built are located in the high-altitude areas of southwest China,High concrete face rockfill dam has become the main dam type of hydropower construction in this area.Panel deflection deformation monitoring is an important part of safety monitoring of high concrete face rockfill dam.The traditional point monitoring instrument has many disadvantages.As a new monitoring method of panel deflection deformation,the fiber optic gyroscope monitoring system realizes the distributed monitoring of deflection.It has been successfully applied in Shuibuya and other high concrete face dams,and the results are remarkable.However,the fiber optic gyroscope monitoring system cannot realize underwater operation monitoring,and has certain application limitations in practical engineering.At the same time,solving the problem of synchronous sampling of sensors on the hardware platform is also of great significance to the improvement of the measurement accuracy of the monitoring system.In addition,the fiber optic gyroscope monitoring system is often affected by the external environment and other factors in the measurement process,resulting in various noises,which in turn affects the measurement accuracy of the monitoring system.Therefore,the analysis and compensation of the main error sources of the FOG monitoring system is a problem to be studied.This paper mainly studies the fiber optic gyroscope monitoring system suitable for underwater operation,and designs its hardware structure.The main error sources of fiber optic gyroscope monitoring system are analyzed,and the main temperature drift error in random error and constant error is modeled and compensated.Finally,taking Jiangpinghe hydropower station as the engineering background,the new monitoring system is applied to the panel deflection monitoring,and the application research is carried out.(1)The error sources of the fiber optic gyroscope monitoring system are analyzed,and the main error sources are determined to be the temperature drift error in the random error and constant error of the fiber optic gyroscope.(2)The fiber optic gyroscope monitoring system suitable for underwater operation is redesigned,including power module,data processing and storage module,sensor module and waterproof cabin module.Aiming at the problem of different sampling frequencies of sensors,a synchronous sampling method based on SPI protocol is studied and verified by outdoor experiments.In order to ensure the stability of the new system and improve the efficiency of data processing,new data processing software and power switch software are designed and developed.(3)Aiming at the random drift error of FOG,the time series analysis method is used to model the random drift signal of FOG,and Kalman filter and adaptive filter are established to filter and compensate it.Finally,the Allan variance method is used to analyze the filtering results,and the effectiveness of the two methods is verified.Among them,the adaptive filtering compensation effect is better.(4)The formation mechanism of temperature drift of fiber optic gyroscope is analyzed and studied.Combining the idea of segmented modeling with PSO-BPNN method,an adaptive temperature drift model based on improved particle swarm optimization BP neural network is established.The model is used to compensate the temperature drift error of fiber optic gyroscope.The results show that the new method can effectively reduce the temperature drift error of FOG and improve the bias stability of the monitoring system.The compensation effect is better than the traditional polynomial fitting modeling method,which has certain engineering practicability.(5)The fiber optic gyroscope monitoring system suitable for underwater operation is applied to the panel deflection monitoring of Jiangpinghe Hydropower Station,and the monitoring results of typical months are analyzed.The results show that the deflection value of the monitoring panel in each month is reasonable,which conforms to the basic deformation law and has no abnormal data.