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Issue 8 ， 2019
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Sensitivity-enhanced optical fiber hydrogen sensor based on multilayer Au-Pd core-shell nanoparticle film
Abstract：Optical fiber hydrogen sensing with high sensitivity and fast response is the future developmental direction in hydrogen sensing technology that will be of great importance in ensuring the safety of hydrogen energy systems. To solve the difficulty in coupling palladium-based hydrogen sensitive materials at the nanoscale to optical devices, Au-Pd core-shell nanoparticle films with rapid hydrogen response characteristics were prepared by aqueous phase synthesis and centrifugal deposition. With an array of Au- Keywords：hydrogen detection;optical fiber hydrogen;Au-Pd nanoparticles;mutli-layer sensitivity enhancement- 123
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Published：2020-08-13 -
Modeling and analysis of orientation measurement error based on polarization imaging
Abstract：To improve the angular accuracy of the polarization imaging orientation sensor, an error propagation model of the polarization imaging orientation sensor based on Stokes vector was established. The principal point deviation, lens distortion, and CMOS planar inclination were studied. First, the polarization azimuth calculation method was derived according to the polarization measurement principle of the Stokes vector. Then, the effects of principal point deviation, lens distortion, CMOS plane tilt, and gray Keywords：polarization imaging;principal point deviation;CMOS plane tilt;CMOS gray response inconsistent- 128
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Published：2020-08-13 -
Observation of vertical distribution of ozone based on differential absorption lidar during summer and autumn in Tianjin
Abstract：Differential absorption lidar combined with near-surface ozone monitoring were used to detect the vertical distribution of ozone in Tianjin from Jun. 23 to Sep. 28, 2018. The monitoring results indicated that the ozone concentration at 300 m above ground showed the same variation tendency as the monitoring values obtained near the ground. In the boundary layer of about 300 m to 1 000 m, the ozone concentration increased with height, but it then decreased at higher altitude. The maximum concentration occurre Keywords：differential absorption lidar;ozone pollution zone;vertical distribution characters;diurnal variation curve- 111
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Published：2020-08-13 -
Impact of polyhedron pyramidal error and installation eccentricity on precision detection of photoelectric encoder
Abstract：In a common method for precision detecton of photoelectric encoders, a polyhedron is joined with a photoelectric encoder and light from an autocollimation setup is reflected by the polyhedron; the precision of photoelectric encoder is then measured by reading the numerical value of the autocollimation. A feasible method to improve measurement efficiency was investigated with respect to the main factors that affect photoelectric encoder detection. Firstly, according to the principle of autocollimator detecti Keywords：photoelectric encoder;precision detection;pyramidal error;eccentricity- 72
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Published：2020-08-13 -
Preliminary test of performance detection and analysis of weak-light detector for space gravitational wave detection
Abstract：To develop a weak-light detector that meets the needs of space gravitational wave detection in the future, the performance detection of weak-light detectors was initially carried out, and the performance parameters, such as responsiveness, response bandwidth and background noise, of the detectors were analyzed, for finding out the method and solution of weak-light detector development that can meet the requirements of future space gravitational wave detection. Firstly, according to the design scheme of the Keywords：space gravitational wave detection;weak-light detector;Taiji- 127
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Published：2020-08-13 -
Application and novel angle measurement error compensation method of circular gratings
Abstract：In practical industrial applications, ambient temperature change is the main source of error in the angular accuracy of the rotating shaft in Portable Articulated Coordinate Measurement Instruments Machines (PACMM). To eliminate this error, this paper proposes a new method to establish a circular grating angle measurement error compensation model with ambient temperature influence factors. First, the harmonic method is used to establish the compensation model of angle measurement error of circular gratings Keywords：precision measurement;circular grating angle measurement;angle measurement error;harmonic compensation;polynomial- 95
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Published：2020-08-13 -
Spatially separated heterodyne grating interferometer for in-plane displacement measurement
Abstract：To measure two Degree-Of-Freedom (DOF) in-plane displacement, a spatially separated heterodyne grating interferometer was designed and built. The optical configuration, measurement principle, and in-plane rotary assembling error of this instrument were investigated. Based on the diffraction of the planar grating and the spatially separated heterodyne grating interferometry, a symmetrical double-diffracted optical configuration was designed and analyzed. The measurement principle and the elimination of perio Keywords：grating interferometry;spatially separated heterodyne interferometry;two degree of freedom;displacement measurement- 97
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Published：2020-08-13 -
Correlation-wavelet method for separation of hyperspectral thermal infrared temperature and emissivity
Abstract：A novel method of thermal infrared temperature emissivity separation based on correlation and wavelet filtering was proposed to alleviate the ill-conditioned equation problem of thermal infrared temperature and emissivity inversions of hyperspectral data. The basis of the utilized correlation method was the idea that wavelet denoising could be introduced to suppress the error caused by inaccurate atmospheric correction to certain extents, effectively improving the inversion precision of thermal infrared tem Keywords：hyperspectral thermal infrared;land surface temperature;land surface emissivity;correlation;multiscale wavelet- 85
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Published：2020-08-13 -
Mutation mechanism particle swarm optimization for camera internal parameter calibration
Abstract：To solve the problem that the calibration accuracy of internal parameters of the camera in the large-size single-camera vision system has great influence on the overall measurement accuracy, this paper presents a virtual stereo calibration method for the internal parameters of the camera based on the Mutation Mechanism Particle Swarm Optimization (MMPSO) algorithm. The method is based on a two-stage optimal strategy. Firstly, a camera imaging model is established to estimate the initial values of the extern Keywords：visual measurement;camera model;Mutation Mechanism Particle Swarm Optimization (MMPSO) algorithm;internal parameters calibration- 107
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Published：2020-08-13 -
Laser derusting mechanism of AH32 steel based on cleaned surface topography
Abstract：To understand the nanosecond laser derusting process and reveal the derusting mechanism, the surface morphology and roughness of AH32 marine steel after laser derusting under different process parameters was studied. First, a nanosecond-pulse laser was used to clean the rust layer of the sample surface under different process parameters. Then, the surface roughness after cleaning was measured using laser scanning confocal microscopy, the micromorphology was measured by scanning electron microscopy, and an e Keywords：laser technology;laser cleaning;derusting;AH32 marine steel;surface roughness- 326
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Published：2020-08-13 -
Ultra-precision phase-shifting locking system of scanning beam interference lithography tool
Abstract：Phase-shifting locking is one of the key aspects of Scanning Beam Interference Lithography (SBIL) in achieving highly accurate exposure stitching of a large grating. To achieve this objective, a phase-shifting locking system was investigated for the stepping/scanning exposure trajectory of SBIL. Firstly, based on a previously proposed homodyne frequency-shifting interference pattern locking system and a heterodyne Littrow grating interferometer, a novel phase-shifting locking system scheme was proposed for SBIL. An experimental setup was then designed for this proposed scheme. Based on the setup, experimental and factor analyses were conducted to facilitate precise phase-shifting positioning control and an accuracy of ±3.27 nm (3σ, Λ=251 nm) was achieved. In addition, an accuracy of ±4.17 nm (3σ, Λ=251 nm) was achieved for phase-shifting locking control using a notch and PID control.Keywords：Scanning Beam Interference Lithography (SBIL);homodyne frequency-shifting phase locking;heterodyne Littrow grating interferometer;phase-shifting locking;notch filter- 158
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Published：2020-08-13
Modern Applied Optics
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Modeling and Verification of Orientation Sensor Error Based on Polarization Imaging
Abstract：To improve the angular accuracy of the polarization imaging orientation sensor， an error propagation model of the polarization imaging orientation sensor based on Stokes vector was established. The principal point deviation， lens distortion， and CMOS planar inclination were studied. First， the polarization azimuth calculation method was derived according to the polarization measurement principle of the Stokes vector. Then， the effects of principal point deviation， lens distortion， CMOS plane tilt， and gray response inconsistency were explored. The Monte Carlo method was used to analyze the measurement error of the polarization azimuth. The rationality of the model established was verified by simulation and skylight imaging experiments. The experimental results show that the CMOS gray response inconsistency has the greatest impact on the measurement error of orientation. In the range of (-6， 6) pixels， the measurement error is within 0.11°， and the mean has an overall offset of 0.12°. The principle point deviation changes (-1.5， +1.5) pixels， the distortion shifts (-1， +1) pixel， the CMOS plane tilt is (-0.5°， +0.5°)， and the CMOS gray response deviation is (-6， +6) pixels; under the joint action， the measurement error of orientation is 0.236 3°(σ). The error propagation model may reflect how the error source impacts the accuracy of orientation measurement， and it provides a basis and reference for optimal design of the polarization imaging orientation sensor.Keywords：polarization imaging;principal point deviation;CMOS plane tilt;COMS gray response inconsistent- 77
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Published：2020-08-13 -
Preliminary test of performance detection and analysis of weak-light detector for space gravitational wave detection
Abstract：To develop a weak-light detector that meets the needs of space gravitational wave detection in the future， the performance detection of weak-light detectors was initially carried out， and the performance parameters， such as responsiveness， response bandwidth and background noise， of the detectors were analyzed， for finding out the method and solution of weaklight detector development that can meet the requirements of future space gravitational wave detection. Firstly， according to the design scheme of the space gravitational wave detection， e.g. Taiji， including laser power， orbit design and star spacing， the parameters of the detector required by Taiji were calculated. Next， three kinds of weaklight detectors were developed by the China Electronics Technology Group Corporation No.44 Research Institute， Southwest Institute of Technical Physics， Shanghai Institute of Technical Physics of the Chinese Academy of Sciences with joint efforts of our research group. Finally， the responsivity， response bandwidth， and background noise of the detectors were tested by the lownoise heterodyne laser interferometry system developed by our research group， and the factors affecting the performance of the detectors were analyzed. The experimental results show that the responsiveness of two detectors is better than 1.8×105 V/W and that the response bandwidth is greater than 10 MHz. The ground noise of the three detectors is lower than 10 pm/Hz@10 mHz (0.1 mHz1 Hz)， and the signaltonoise ratio is higher than 20 dB. According to the aforementioned experimental results， the three detectors have the potential to meet the requirements of the Taiji Pathfinder in terms of responsiveness， response bandwidth， and signal-to-noise ratio.Keywords：space gravitational wave detection;weak-light detector;Taiji- 74
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Published：2020-08-13 -
Laser derusting mechanism of AH32 steel based on cleaned surface topography
Abstract：To understand the nanosecond laser derusting process and reveal the derusting mechanism， the surface morphology and roughness of AH32 marine steel after laser derusting under different process parameters was studied. First， a nanosecond-pulse laser was used to clean the rust layer of the sample surface under different process parameters. Then， the surface roughness after cleaning was measured using laser scanning confocal microscopy， the micromorphology was measured by scanning electron microscopy， and an elemental analysis was performed using an energy dispersive spectrometer. Finally， the nanosecond laser derusting mechanism of AH32 marine steel was revealed combined with the experimental results. The experimental results indicated that the cleaned morphology was improved， and that the surface roughness was reduced under stepwise laser cleaning with energy densities of 30.6 and 10.2 J/cm2 at a scanning speed of 3 000 mm/s. Moreover， under the above cleaning conditions， the micromorphology of the matrix exhibited a micromelting state after laser derusting， in which the spot was smooth and uniform and the edge of the spot was distributed with a dendritic mastoid structure. It can be concluded that the use of a stepwise laser cleaning process can yield a better cleaning effect and higher cleaning efficiency. The derusting mechanism mainly includes hole blasting and melting-vaporization.Keywords：laser technology;laser cleaning;derusting;AH32 marine steel;surface roughness- 58
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Published：2020-08-13 -
Ultra-precision phase-shifting locking control of scanning beam interference lithography tool
Abstract：Phase-shifting locking control is one of the key points for a scanning beam interference lithography (SBIL) tool to achieve the exposure stitching for a large size grating with high accuracy. In order to achieve high accuracy exposure stitching for large size holographic grating, a phase-shifting locking control study was done for a stepping/scanning exposure trajectory of SBIL. Firstly, based on the previously proposed homodyne frequency-shifting interference pattern locking system and heterodyne Littrow grating interferometer, a novel phase-shifting locking scheme and control strategy for SBIL tool is proposed. After that, an experimental setup is built for this novel scheme. Finally, based on the experimental setup, an experiment and factor analysis of controlling accuracy is performed for the performance of phase-shifting positioning control, and a phase-shifted positioning control accuracy of ±3.27 nm (3σ, Λ=251 nm) was realized. At the same time, as for the performance of phase-shifting tracking locking control, based on the experimental analysis, the phase-shifting tracking locking control accuracy reaches to ±4.17 nm (3σ, Λ=251 nm) by a notch & PID control.Keywords：Scanning Beam Interference Lithography (SBIL);homodyne frequency-shifting phase locking;heterodyne Littrow grating interferometer;phase-shifting locking;notch filter- 65
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Published：2020-08-13 -
Optimized Design of High-mode Main Support Structure for Airborne Spectrometer
Abstract：To meet the requirements of the high dynamic characteristics and the low quality of the main support structure, this paper carries out the optimized design and test verification of the main support structure. Firstly, to solve the problem that classic support structures cannot be applied to this system, a general structural form combining the frame type structure and the thin-walled tubular structure is proposed, which is convenient to integrate the hood and structure to reduce the quality and ensure the rigidity. Secondly, multi-variable integration optimization method is adopted to improve the first-order mode from 127 Hz to 156 Hz when the quality requirement is also met. This fact indicates that the dynamic characteristics has been effectively improved. Then, in order to determine the influence of the vibration environment on the system MTF, the influence of the vibration environment on the system MTF is analyzed by the combination of finite element analysis and sensitivity matrix. The scope of application shows that the structure can be applied to an airborne system with a pixel size bigger than 10μm. Finally, the effectiveness and feasibility of the design method and analysis process are verified by the vibration test and the wavefront aberration detection test. The optimized design method proposed in this paper can provide reference for the optimized design of airborne remote sensing instrument structure. This paper will contribute to the development of structure design technique for airborne remote sensing instruments.Keywords：airborne spectrometer;main supporting structure;integrated optimization;vibration environment;modulation transfer function- 66
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Published：2020-08-13 -
A method of servo system resonance suppression based on Structure filter
Abstract：Aiming at the problem of mechanical resonance in the control system of Aeronautical optoelectronic stabilization platform, a novel structural filter based on double T notch filter is proposed. The new structure filter consists of two double T notch and a low-pass filter, which can suppress both resonant and anti-resonant peaks, and overcome the defect that a single notch filter cannot handle the anti-resonance. Compared with the double quadratic filter, the parameter adjustment of the structural filter is more flexible, and its peak size and width can be adjusted at the same time. The experimental results show that compared with the double quadratic filter, the resonance curve fitted by the structural filter matches the actual sweep curve better. The stability accuracy of the control system is improved by 5.74 times and the closed-loop bandwidth is increased by 4.54 times，after adding structural filter to compensate the model. The new structure filter has obvious effect on suppressing mechanical resonance and improving the performance of control system.Keywords：mechanical resonance;control;notch filter;structural filter;modeling- 69
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Published：2020-08-13 -
Design of infrared target system with Zhang Zhengyou calibration method
Abstract：The precise infrared target system (IRTS) plays a key role in infrared imaging system. Base on the Zhang Zhengyou calibration method, a simple precision target is designed by the properties of material thermal and surface radiation. The design elements of IRITS are presented by the principle of Zhang Zhengyou calibration method. With the mechanism of radiation, the thermodynamic theory and position relation of feature position, the target plan, possessing high and low radiation areas with sharp boundary, are designed. And then the error analysis of target plan is implemented by the aging principle. The experiments are deployed with the precise infrared target system. The designed IRITS can supply feature points by sharp boundary from different radiation areas for the infrared camera, and the root-mean-square of back-projection error is leas than 0.16 pixel. These results indicated that the IRITS can be used to calibrate infrared camera precisely.Keywords：target system;infrared imaging system;camera calibration- 91
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Published：2020-08-13 -
Image Style Transfer Based on Improved CycleGAN
Abstract：Image style transfer exploits the specified style for modifying the given image. The generative adversarial networks (GAN) introduction to image style transfer can reduce the user intervention, achieve the rich results. However, in some cases the pair data required by the classical GAN is difficult to obtain. In order to cancel the pair data requirement and improve the style transfer efficiency, the paper proposes an image style transfer method based on the improved cycle-consistent adversarial networks (CycleGAN), in which the deep residual network (ResNet) adopted by the conventional network generator is replaced by the dense connection convolution network (DenseNet), and a novel loss function composed by the same mapping loss and the perceptual loss is used for measuring the style transfer loss. The experiments of building image transferred by the oil, sketch and ink painting style are conducted, and the comparison among the results transferred by wasserstein generative adversarial networks (WGAN), the classical CycleGAN and the improved CycleGAN is implemented. The experiments demonstrate that PSNR of the image generated by the put forward method increases 6.27% on average, and SSIM increases about 10%. So the improved CycleGAN image style transfer method could generate the excellent style transfer image.Keywords：image style transfer;CycleGAN;DenseNet;ResNet- 96
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Published：2020-08-13 -
Fast star identification algorithm based on multi-feature matching
Abstract：With the improving detection sensitivity of star sensor, the number of stars in star catalog increases dramatically, which reduces the identification speed and rate of star identification. To improve the identification speed and identification rate, on the foundation of triangle algorithm, a fast star identification algorithm based on multi-feature matching is proposed. Firstly, the original star catalog is preprocessed, which is then partitioned using the inserted icosahedron of celestial sphere. Then the navigation feature library is constructed with the sides and the product of the radiuses of circumcircle and incircle as feature values. In addition, the navigation feature library is stored in blocks according to the hash function. In the process of star identification, the product of the radiuses of circumcircle and incircle in observation triangle is used to rapidly locate the block of navigation feature library, and then it is used to filter the feature triangles, based on which triangle distances are used for further match to get a preliminary identification result. Finally, the sub-regions of celestial sphere in the field of view (FOV) is got, and then other navigation stars are identified in the sub-regions. The experiment results indicate that identification performance of the proposed algorithm is related to the number of blocks. Based on a reasonable number of blocks, the proposed algorithm has advantages in identification speed and rate as well as the robustness to star magnitude noise and false stars than common triangle algorithms. The average identification time and identification rate of the proposed algorithm is 246.397 ms and 98.58 percent respectively, which can meet the requirement of star sensor for high identification speed and rate.Keywords：star sensor;star identification;celestial partition;multi-feature matching- 70
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Published：2020-08-13 -
Multi-dimensional High precision calibration method for line-scan camera
Abstract：Aiming at the problem of limited adaptability and accuracy of the exact measuring angle method which only calibrates the principal point and the distortion on one-dimensional direction when calibrating line-scan camera, a multi-dimensional high-precision calibration method for line-scan camera is proposed. First, the inner orientation elements model of line-scan camera is analyzed. Then a multi-dimensional calibration method based on two axis precise rotation stage is proposed for the model, and the detailed calibration steps and data processing methods are given. Finally, the calibration results of the proposed method are compared with those of the exact measuring angle method. The results shown that reprojection error of the calibration method proposed in this paper is 0.34 pixel, which significantly improve the calibration precision compared to the 1.25 pixel of the exact measuring angle method. The proposed calibration method does not require alignment and the calibration process is simple.Keywords：line-scan camera;high precision calibration;two-dimensional calibration;precision measurement- 61
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Published：2020-08-13
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Optimal design and experiment of a high-bandwidth two-degree-of-freedom parallel nanopositioning stage
Abstract：A high-bandwidth, two-degree-of-freedom nanopositioning stage based on the optimization of a flexible beam is proposed with the aim of improving the low-bandwidth performance, relative low-travel range, and poor coupling performance of the scanning positioning stage of Atomic Force Microscopy. Design optimization, simulation verification, and experimental analysis of the proposed stage are conducted as part of this process. Firstly, a parallel compliant moving stage composed of a doubly clamped beam and par Keywords：compliant nanopositioning stage;high-bandwidth;optimization design;resonant frequency- 111
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Published：2020-08-13 -
Optimized design of high-mode main support structure for airborne spectrometer
Abstract：To meet the requirements of high dynamic characteristics and overcome the low quality of the main support structure, an optimized design was devised and test verification of the main support structure was conducted. First, to solve the problem that classic support structures could not be applied to this system, a general structural form combining a frame-type structure and a thin-walled tubular structure was proposed. This form conveniently integrates the hood and structure to improve quality and ensure rig Keywords：airborne spectrometer;main supporting structure;integrated optimization;vibration environment;Modulation Transfer Function(MTF)- 121
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Published：2020-08-13 -
Hysteresis nonlinear law of piezoelectric ceramic actuator
Abstract：In this study, the hysteresis nonlinear law of piezoelectric ceramics was explored to provide a reference and theoretical basis for further correction of hysteresis nonlinearity. A hysteresis model was obtained through experimental measurements, and experimental data were analyzed. The corrected straight line of the rising trajectory was fitted; the voltage difference between the rising and falling trajectories at the same displacement was obtained as the compensation voltage; and the input voltage at the s Keywords：piezoelectric ceramic driver;hysteresis nonlinear law;polynomial relationship;repeatability- 125
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Published：2020-08-13 -
Dynamic model of spherical parallel mechanism for wheel-leg hybrid mobile robot
Abstract：To meet the new requirements for mobile robots in the field of modern engineering and expand the working opportunities of mobile robots, a spherical parallel leg mechanism of a wheel-leg composite mobile robot was proposed in this study. First, based on the closed-loop constraint equation and rotation transformation matrix of the spherical parallel leg mechanism, a mathematical model of its inverse position solution was constructed. Next, an analytical solution of the forward position solution of the spheri Keywords：wheel-legged mobile robots;spherical parallel mechanism;dynamic model;degree of freedom of mechanism;screw theory- 119
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Published：2020-08-13 -
A method of servo system resonance suppression based on structure filter
Abstract：To address the problem of mechanical resonance in the control system of an aeronautical optoelectronic stabilization platform, a novel structural filter based on a double-T notch filter was proposed in this study. The new structure filter, consisting of two double-T notches and a low-pass filter, could suppress both resonant and anti-resonant peaks while overcoming the problem whereby a single notch filter could not deal with anti-resonance. Compared to that of the double quadratic filter, the parameter adj Keywords：mechanical resonance;control;notch filter;structural filter;modeling- 82
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Published：2020-08-13
Micro/Nano Technology and Fine Mechanics
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Data collection and irradiance conversion of lunar obsevation for MERSI
Abstract：Lunar calibration is an effective method for visible and near-infrared spectrum remote sensors. Original lunar observation data should be pre-processed into lunar full disk irradiance in order to compare them with a lunar radiation model. This paper describes the pre-processing of lunar data of the MERSI on the FY-3D satellite. The data pre-processing includes two steps. First, the lunar observation data are identified from the massive space view data. Then, the identified lunar original digital count is co Keywords：unar calibration;Medium Resolution Spectral Imager (MERSI);imager;lunar irradiate;over sample- 135
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Published：2020-08-13 -
Design of infrared target system with Zhang Zhengyou calibration method
Abstract：A precise infrared target system (IRTS) plays a major role in an infrared imaging system. In this study, using the Zhang Zhengyou calibration method, we design a simple precision target based on the properties of a material's thermal and surface radiation. The design elements of the IRITS are presented according to the principles of the Zhang Zhengyou calibration method. Based on the mechanism of radiation, thermodynamic theory, and position relation of the feature position, a target plan possessing high an Keywords：target system;infrared imaging system;camera calibration- 161
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Published：2020-08-13 -
Image styletransfer based on improved Cycle
Abstract：Image style transfer exploits a specified style to modify given image content. An automatic image style transfer based on a Generative Adversarial Network (GAN) can reduce the workload and yield rich results. In some cases, the pair datasets required by the classical GAN were difficult to obtain. To overcome the limitations of paired datasets by a traditional GAN and improve the efficiency of style transfer, this study proposed an image style transfer method based on an improved Cycle-consistent adversarial Keywords：image style transfer;CycleGAN;DenseNet;ResNet- 253
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Published：2020-08-13 -
Co-saliency detection based on objectness and multi-layer linear model
Abstract：To address the confusion and low accuracy of salient objects in co-saliency detection for image groups with complex environments, we proposed a co-saliency detection model based on objectness and a multi-layer linear model. First, we calculated the inter-saliency values using the background guidance factor weighted by saliency prior and objectness probability. We then designed a local region feature to calculate the intra-saliency values. The zero, first, and second Hu moments of the image were used to integrate the two-stage saliency values. Finally, saliency subgraphs were adaptively fused using a multi-layer linear model. Experimental results reveal that the AP scores of the proposed algorithm are 87.80% on iCoseg datasets and 83.50% on the MSRC dataset. Results from the evaluation of other experimental indicators are also improved significantly. The detected salient objects are more accurate and the adaptability of the algorithm is enhanced.Keywords：co-saliency detection;multi-layer linear model;objectness;image moments- 99
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Published：2020-08-13 -
Model reconstruction and pose optimization of non-cooperative rotating space target
Abstract：For the model reconstruction and pose estimation of non-cooperative rotating space targets with unknown model, the technology of graph-based optimization SLAM was applied to reduce the cumulative error in the pose tracking process by using 3D point clouds acquired through LiDAR. First, the relative pose between adjacent key frames was calculated by the Iterative Closest Point (ICP) algorithm, and the pose of the current key frame was obtained by the pose tracking method, thereby constructing the pose graph Keywords：non-cooperative rotating target;loop closure detection;model reconstruction;pose graph optimization- 127
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Published：2020-08-13 -
Application of magneto-optical imaging magnetic flux leakage characteristics in contour reconstruction of welding defects
Abstract：In this study, to detect and evaluate welding defects effectively, magnetic flux leakage characteristics of magneto-optic imaging under alternating magnetic field excitation are proposed for application in the contour reconstruction of welding defects. A magnetic flux leakage reconstruction model was also established to study the two-dimensional contour characteristics of welding defects. First, based on the formation mechanism of a leakage magnetic field under an alternating magnetic field, the relationshi Keywords：leakage magnetic field signal;defect contour;neural network;magneto-optical imaging- 110
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Published：2020-08-13 -
Fast star identification algorithm based on multi-feature matching
Abstract：With the improving detection sensitivity of star sensors, the number of stars in star catalogs has increased dramatically, reducing the speed and rate of star identification. To improve the identification speed and rate, a fast star identification algorithm based on multi-feature matching and built upon the foundation of the triangle algorithm was proposed. First, the preprocessed star catalog was partitioned using the inserted icosahedron of the celestial sphere. Then, the navigation feature library was co Keywords：star sensor;star identification;celestial partition;multi-feature matching- 134
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Published：2020-08-13 -
Magnetic source single-point positioning by tensor derivative invariant relations
Abstract：It is desirable to avoid the error and noise sensitivity of second-order tensor data leading to the disadvantages of low positioning accuracy with the Euler inversion method of magnetic object single-point positioning. For single-point positioning with only first-order tensor data, a method based on tensor derivative invariant relations is proposed. For the analysis of the magnetic dipole source tensor invariant and eigenvalue, two tensor derivative invariant relations were derived. The angle between the ma Keywords：magnetic gradient tensor system;magnetic dipole;tensor invariant relation;single-point positioning;error correction- 99
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Published：2020-08-13 -
Variable exponential chromaticity filtering for microscopic image segmentation of wire harness terminals
Abstract：To accurately determine the inner diameter contour of a microscopic image of a harness terminal for subsequent data analysis, a microscopic image segmentation algorithm based on variable exponential filtering is proposed in a chromaticity-brightness space. First, based on the color distribution characteristics of the microscopic image of a color wire harness terminal, color images in the red, green, and blue color space are converted to the chroma brightness space. In addition, lighting effects and separate Keywords：image segmentation;color space;chromaticity transformation;harness terminal;variable exponential chroma filter- 106
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Published：2020-08-13 -
Multi-dimensional high-precision calibration method for line-scan camera
Abstract：In this study, to address the problem of limited adaptability and accuracy of the exact measuring angle method, which only calibrates the principal point and distortion in a one-dimensional direction with a line-scan camera, a two-dimensional high-precision calibration method for a line-scan camera was proposed. First, the inner orientation elements model of a line-scan camera was analyzed. Then, a two-dimensional calibration method based on a two-axis precise rotation stage was proposed for the model. Deta Keywords：line-scan camera;high precision calibration;two-dimensional calibration;precision measurement- 132
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Published：2020-08-13
Information Sciences
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