Intelligent machine fault diagnosis technology is irreplaceable in modern industrial production. Tremendous development has been made in recent years in researching deep learning (DL) based diagnosis methods. But most current DL-based methods still face the challenge, which does not consider the sufficient information between different views of signal and incorporate specific knowledge. To address this issue, this paper proposed a multi-view feature encoding model (MVFEM) by embedding the wavelet transform knowledge to realize the fault diagnosis of rotary machine. To this end, the proposed MVFEM 1) utilizes multi-branch wavelet convolution via using different wavelet basis functions to capture the multi-view features between different wavelet character views, 2) feeds the multi-view feature into a temporal-spatial block to mine the temporal-spatial related information and 3) fuse the multi-view feature as one feature for diagnosis. With the capability to mine the complex relation from different views of individual vibration signal, the proposed MVFEM can leverage the information from multi-view features to monitor the condition of the rotary machine and detect the faults. The performance of the MVFEM in rotary machine diagnosis is validated on the experiment and compared with other related methods. Experimental results illustrate that the proposed MVFEM can learn useful multi-view feature to realize accurate fault diagnosis.
Inertial navigation system (INS) aided by odometer can achieve ideal accuracy in pipeline surveying, and hence is widely used. However, because of mechanical manufacturing errors, there are installation angle errors between INS and odometer as well as the odometer scale factor error, which will decrease the system position accuracy. To achieve high accuracy, these errors need be calibrated periodically. In this paper, a pre-calibration method based on similarity principle is proposed, which is used for odometer installation error and scale factor calibration in pipeline probe autonomous navigation system. The proposed method has no special requirements for the number of landmarks. The effectiveness of the proposed method is verified by the simulation and filed test. The field pipeline test shows that the position accuracy of the integrated navigation system is less than 0.5%D, which satisfies the application of long-distance horizontal position in pipeline surveying.
There are the scale factor error of LDV (laser Doppler velocimeter) and the misalignment between the SINS (Strapdown inertial navigation system) and the vehicle in a SINS/LDV integrated navigation system. In this paper, the effects of these errors on the attitude, velocity and position of dead reckoning are derived, and a new online calibration method aiming to calibrate the scale factor of LDV and the misalignment between the SINS and the vehicle for the integrated system is put forward. This method, which is utilize the velocity and position of the Global Position System (GPS) as references, use the velocity error and position error of dead reckoning to estimate these errors. Through simulation and experiment, the validity and feasibility of the method are verified. The results show that the scale factor and the misalignment can be calibrated with satisfying accuracy, and the related research can provide technical support for high precision navigation of SINS/LDV integrated navigation systems.
Inertial navigation system has been the core component of both military and civil navigation systems. Dual-axis rotation modulation can completely eliminate the inertial elements constant errors of the three axes to improve the system accuracy. But the error caused by the misalignment angles and the scale factor error cannot be eliminated through dual-axis rotation modulation. And discrete calibration method cannot fulfill requirements of high-accurate calibration of the mechanically dithered ring laser gyroscope navigation system with shock absorbers. This paper has analyzed the effect of calibration error during one modulated period and presented a new systematic self-calibration method for dual-axis rotation-modulating RLG-INS. Procedure for self-calibration of dual-axis rotation-modulating RLG-INS has been designed. The results of self-calibration simulation experiment proved that: this scheme can estimate all the errors in the calibration error model, the calibration precision of the inertial sensors scale factor error is less than 1ppm and the misalignment is less than 5″. These results have validated the systematic self-calibration method and proved its importance for accuracy improvement of dual -axis rotation inertial navigation system with mechanically dithered ring laser gyroscope.
As a highly reliable positioning and orientation equipment, the redundant inertial navigation system (INS) is widely used in aerospace and other fields. For INS, high-precision calibration is the basis of high-precision navigation. Different from the calibration error modeling method of traditional orthogonal system, the nonorthogonal redundant ring laser gyro INS is installed with multi-device obliquely, and with the complexity of the configuration, the difficulty of separating the calibration parameters is also increased. Therefore, it is very significant to find a high precision calibration scheme for the non-orthogonal redundant INS. In this paper, the high precision calibration of non-orthogonal redundant INS in laboratory is studied, and a new calibration model of redundant system is summarized. A regular tetrahedral configuration prototype consisting of four Ring Laser Gyro and four Quartz Accelerometer is designed, and the calibration error modeling method and calibration accuracy are verified.
As an indispensable equipment in inertial technology tests, the three-axis turntable is widely used in the calibration of various types inertial navigation systems (INS). In order to ensure the calibration accuracy of INS, we need to accurately measure the initial state of the turntable. However, the traditional measuring method needs a lot of exterior equipment (such as level instrument, north seeker, autocollimator, etc.), and the test processing is complex, low efficiency. Therefore, it is relatively difficult for the inertial measurement equipment manufacturers to realize the self-inspection of the turntable. Owing to the high precision attitude information provided by the laser gyro strapdown inertial navigation system (SINS) after fine alignment, we can use it as the attitude reference of initial state measurement of three-axis turntable. For the principle that the fixed rotation vector increment is not affected by measuring point, we use the laser gyro INS and the encoder of the turntable to provide the attitudes of turntable mounting plat. Through this way, the high accuracy measurement of perpendicularity error and initial attitude of the three-axis turntable has been achieved.
Inertial navigation system has been the core component of both military and civil navigation systems. Before the INS is put into application, it is supposed to be calibrated in the laboratory in order to compensate repeatability error caused by manufacturing. Discrete calibration method cannot fulfill requirements of high-accurate calibration of the mechanically dithered ring laser gyroscope navigation system with shock absorbers. This paper has analyzed theories of error inspiration and separation in detail and presented a new systematic calibration method for ring laser gyroscope inertial navigation system. Error models and equations of calibrated Inertial Measurement Unit are given. Then proper rotation arrangement orders are depicted in order to establish the linear relationships between the change of velocity errors and calibrated parameter errors. Experiments have been set up to compare the systematic errors calculated by filtering calibration result with those obtained by discrete calibration result. The largest position error and velocity error of filtering calibration result are only 0.18 miles and 0.26m/s compared with 2 miles and 1.46m/s of discrete calibration result. These results have validated the new systematic calibration method and proved its importance for optimal design and accuracy improvement of calibration of mechanically dithered ring laser gyroscope inertial navigation system.
Taking the one-dimensional Laser Doppler Velocimeter (LDV) and a certain type of Laser Gyro Strapdown Inertial Navigation System (SINS) developed our staff room for object, the paper verifies that dynamic calibration technique can be achieved by SINS/LDV integrated system on the basis of the analysis of the software and hardware conditions. Extended Kalman filter states of SINS/LDV integrated system were chosen based on the error models of SINS and LDV. Using the difference of the output speed of the SINS and LDV as measurement, the error of bias and scale factor of the integrated navigation system are estimated effectively by setting up a reasonable calibration path. The effectiveness of the algorithm is further verified through the vehicular experiments. The results of experiments show that the dynamic calibration technique can be achieved through SINS/LDV integrated system and ensure the maneuverability of terrestrial inertial navigation system. The estimate of LDV scale factor is about 0.003%. The estimate error of accelerometer bias no more than 13μg. The estimate error of gyroscope drift no more than 1.7×10-3°/h. The yaw angle error is less than 0.19 ' within 20min.
The actual combat effectiveness of weapon equipment is restricted by the performance of Inertial Navigation System (INS), especially in high reliability required situations such as fighter, satellite and submarine. Through the use of skewed sensor geometries, redundant technique has been applied to reduce the cost and improve the reliability of the INS. In this paper, the structure configuration and the inertial sensor characteristics of Skewed Redundant Strapdown Inertial Navigation System (SRSINS) using dithered Ring Laser Gyroscope (RLG) are analyzed. For the dither coupling effects of the dither gyro, the system measurement errors can be amplified either the individual gyro dither frequency is near one another or the structure of the SRSINS is unreasonable. Based on the characteristics of RLG, the research on coupled vibration of dithered RLG in SRSINS is carried out. On the principle of optimal navigation performance, optimal reliability and optimal cost-effectiveness, the comprehensive evaluation scheme of the inertial sensor configuration of SRINS is given.
The basic composition and measuring principle of Laser Doppler Velocimeter (LDV) are discussed, and the superiority of LDV been the external velocity observation system of the strapdown inertial navigation system(SINS) is analyzed. For study of the RLG inertial navigation system and the LDV which is self-developed by our own department, the feasibility of SINS/LDV composite system is proved, and vehicle navigation tests have been conducted. Taking the DGPS as reference, the results show that the maximum positioning error of SINS/LDV composite system is 8 meters in one hour test while the maximum positioning error of pure SINS reaches 1130 meters. Results show that the SINS/LDV composite system can effectively inhibits the time accumulated navigation errors, and the high accuracy self-contained navigation can be realized.
A finite element model of the hemispherical resonator gyro (HRG) is established and the natural frequencies and
vibration modes are investigated. The matrix perturbation technology in the random finite element method is first
introduced to analyze the statistical characteristics of the natural frequencies of HRG. The influences of random material
parameters and dimensional parameters on the natural frequencies are quantitatively described based on the probability
theory. The statistics expressions of the random parameters are given and the influences of three key parameters on
natural frequency are pointed out. These results are important for design and improvement of high accuracy HRG.
Different methods for stripping cladding light in the high-power fiber laser have been presented. Original fluoroacrylate jacket of fiber selected 50mm-length is continuous removed, then use three different index polymers recoated the selected section to make the uniform light stripping possible. The power-handling capability of the device is
tested over 140W cladding light, attenuation of 15dB is achieved and the local temperature does not exceed 70°C.
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