Abstract:The photon doppler velocimetry system has the advantages of strong anti-interference ability and wide range of velocity measurement. It is suitable for low signal-to-noise ratio and poor signal quality measurement occasions. The working principle of photon doppler velocimetry system is introduced. Four commonly used signal demodulation methods, fringe method, phase demodulation method, short-time Fourier transform method and wavelet transform method, are described in detail. The four signal demodulation methods mentioned above are used to demodulate the doppler signal modulated by harmonic oscillation. The advantages, disadvantages and applicability of different signal demodulation methods are shown intuitively. The experimental results show that the phase demodulation method is most suitable for demodulating the vibration signal of photon doppler velocimetry system. Finally, the feasibility of using recursive Hilbert transform to reduce the orthogonality error of phase demodulation method is discussed, and the effectiveness of this method is verified by simulation experiments.

Abstract:A monocular stereo vision-based geometric error identification method for machine tools rotary axes is proposed to consider both cost and accuracy of vision measurement. To accurately describe the full-range motion information of the rotary axes, an error amplification-based feature target with the precise low-reflection target balls in circumferential uniform distribution is designed to guarantee the high-uniformity, high-contrast, and high signal-to-noise ratio (SNR) imaging. A simulation analysis method for monocular stereo imaging optical path is proposed to quantitatively analyze and select system structure parameters. With the Zhang’s calibration results, the three-dimensional trajectories of rotary axes can be reconstructed from the acquired sequence images. The accuracy verification experiments and error identification results show that the root mean square error (RMSE) of 0.049 mm is less than 1/3 of the mean measurement error, satisfying the test requirements.

Abstract:Turntable is a kind of equipment used for inertial component detection, which has high requirements for the structural performance of its shafting. The finite element method is used to analyze the main axle structure of ultra-low speed turntable in this paper. The analysis plays a guiding and verifying role in the design of turntable. Turntable bearings adopt air bearing. According to the actual situation, the spindle model is established to calculate the equivalent stiffness of air bearing. Then static analysis is carried out to solve the deformation and stress of the model in the static state. Finally, dynamic analysis is executed to obtain the vibration mode and natural frequencies of the structure, which verifies the rationality of the structure.

Abstract:For a hydraulic servo actuator, a fault monitoring method based on model comparison is proposed. This paper expounds the composition and working principle of the actuator, then analyses its failure mode, establishes the mathematical model and simulation model of the hydraulic servo actuator by using the monitoring method based on model comparison, and verifies the simulation model by using the software of matlab, which proves that the simulation model established in this paper is reliable and close to the actual state. It provides a reliable basis for fault monitoring of hydraulic servo actuator.

Abstract:In the application technology of terahertz spectrum analyzer, Chirp transform spectrum analysis uses surface acoustic wave filter, which can guarantee the parameters of intermediate frequency and resolution, and meet the strict requirements of stability and power consumption in deep space exploration. However, the Chirp transform spectrum analyzer in China can only process 400 MHz bandwidth input signal, which can not fully meet the application needs. In order to improve the bandwidth, a frequency analyzer with 1 GHz bandwidth and 3.2 GHz center frequency is designed in this paper. The digital part is implemented and the results are analyzed and validated.

Abstract:A high stability double-pass laser interferometer that can be used for measuring the length changes of materials is introduced. Since the measurement beam and the reference beam of the interferometer have similar traveling pathes and the optical path difference is mainly caused by the sample itself, the interferometer has has strong resistance to external disturbances such as ambient temperature changes and vibration. The stability of the system is verified by the experiment of measuring the reflection film of a plane mirror, which shows that the standard deviation of the measurement data is 4.2 nm in 6.5 hour. This interferometer can be used for high-accuracy dimensional change measurement such as the measurement of the coefficient of linear thermal expansion of materials.

Abstract:A new non-contact automatic calibration device for scraper fineness meter is developed by using the design method of spectral confocal sensor and laser displacement sensor. By using the advantages of spectral confocal sensor, the measuring points of scraper fineness meter can be precisely located, and the wear of probe and measuring surface caused by contact measurement can be avoided. The experiment proves that the device has good repeatability, high efficiency, accurate and reliable measurement results, and has important technical popularization value.

Abstract:In order to solve the problems of complex operation, long time-consuming and low measurement accuracy of traditional manual calibration method in the calibration process of large-range displacement sensors, an automatic calibration device for large-range displacement sensors was developed. The hardware composition and software design of the device are introduced in detail, and its innovative features are expounded. The device is used to calibrate LVDT displacement sensor and evaluate its measurement uncertainty. Experiments show that the displacement sensor calibration device has high measurement accuracy and good operation stability, can effectively improve the verification efficiency, can replace manual automatic verification of displacement sensors, and has important technical reference significance.

Abstract:Based on design of point sound source which can be moved in space, calibration device used in calibration of sound source localization system was built. Dynamic characteristics evaluated methods were put forward, experiment results were acquired and main influences were analyzed. Uncertainties of calibration results were evaluated. It is useful to support the calibration technique for lab calibration of dynamic characteristics of sound source localization system using in automobile and aero vehicle movement noise identification.

Abstract:In order to understand the decay rate of HMX-based explosives before and after aging, two kinds of HMX-based explosives with different binders were selected for aging test. The density of explosives was obtained by calculation, and the detonation velocity of the samples was obtained by electric detonator detonation test method. The results show that the aging time has different effects on the density of explosives. The aging of 8 days is the boundary point between the density changes of two kinds of explosives. The density of the samples changes greatly over 8 days; the detonation speed of the two explosives decreases significantly with the aging time, but The explosive rate of H-2 explosives is always higher than that of H-1 explosives.

Abstract:The mechanical properties of hammer mass have a great impact on the result of impulse force calibration. In this paper, the finite element method is used to analyze the structural design and load mode of the hammer mass, the influence of the above factors on the dynamic characteristics of hammer mass is obtained, the rules that should be followed in hammer mass design in impulse force calibration are put forward.

Abstract:This paper introduces the working principle and signal output characteristics of the dynamometer based on the parallel Method of force Transducer. Taking the dynamometer connected in parallel with two force sensors as an example, the influence of the sensitivity and linearity of the force Transducer on the measurement error of the parallel dynamometer is analyzed in detail, and the related verification tests are carried out, which can provide technical reference for the application of the parallel dynamometer.

Abstract:As the environmental adaptability of products has received more and more attention from all walks of life, the performance evaluation of environmental test equipment has also increased. In the activities of measuring and evaluating environmental test equipment, there are existing measurement instruments. The limitations have become more and more prominent, especially with the increase of data traceability requirements, the improvement of test instrument use efficiency, and the reduction of human factors such as personnel operation during measurement and testing, which have become the technology of general concern in environmental test activities. problem. This paper presents an overview of a new cloud-based instrument for the traceability of environmental test equipment performance parameters. The instrument combines the Internet cloud service with the traditional measurement and test instrument to realize the remote operation of the measurement test work, reduce the dependence on the personnel during the measurement test process, improve the efficiency of the measurement test service, and have the depth of the test data. Analysis, display and other functions.

Abstract:As the increase of the pressure calibration procedure, the existing data management method of the pressure calibration is insatiable in the demand of data querying and effective management. The pressure calibration data management system, which based on Visual Basic program and ACCESS, could improve the efficiency of verification data management, make the data reliable in surveying data processing, analyze the data accuracy, assess the life of instruments and guarantee the accuracy and reliability of test pressure data.

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