WANG Hao, LI Xinghui, XIAO Wei, QIANG Xiang, WANG Xiaohao
当前状态:一校优先
摘要:This study addresses the need for rapid and accurate measurement of micro-volume liquid (approximately 0.1 mL to 0.5 mL) within transparent tubes in industrial production. A machine vision-based measurement method is proposed, incorporating a specifically designed imaging system and an adaptive neighborhood-weighted brightness analysis algorithm to reliably extract the pixel length of liquid segments. This approach effectively overcomes challenges such as bubble interference, uneven lighting, and reflective surfaces of the tube. On this basis, two measurement strategies are proposed: the first method is a calibration-based measurement method using static weighing, which establishes a quantitative model by fitting the relationship between the pixel length of the liquid segment and the actual volume; the second method is a homography-based image feature coordinate transformation measurement method, which maps the pixel coordinates to the physical space and calculates the volume by incorporating the tube's inner diameter. Experimental results demonstrate that under complex conditions, the proposed method achieves measurement accuracies of approximately 98.3% and 98.4%, respectively, effectively meeting the demands for rapid micro-volume liquid measurement in industrial settings. This method holds significant application value and potential for widespread adoption.
FU Zhiwei, ZHOU Tao, ZHANG Guimei, XIE Bingxian, SU Xing, HUANG Wen, HAI Kuo
当前状态:一校优先
摘要:In order to overcome the technological limitations of traditional magnetorheological finishing machines, which have the polishing wheel mounted on top and face challenges when processing optical components with high steepness, and to address the limitation that existing virtual axis technology is only suitable for a small angle range, this paper proposes a compound linkage polishing technology that combines a fixed mechanical axis with a virtual axis and features an under-mounted fixed polishing wheel. Firstly, based on the structural characteristics of the magnetorheological finishing machine with an under-mounted fixed polishing wheel, the post-processing model for the compound linkage polishing of the machine tool’s mechanical axis and virtual axis is established using the Denavit-Hartenberg (DH) method and is theoretically verified by a geometric approach. Secondly, the accuracy of the post-processing model are verified through spot-picking experiments on a virtual shaft concave spherical surface and uniform polishing experiments on a fused silica concave spherical surface with a diameter of 150 mm and a radius of curvature of 150 mm. Finally, a concave spherical surface made of molten fused silica, with a diameter of 170 mm, a radius of curvature of 158 mm, and a maximum normal angle of 32.54°, is polished and modified. The experimental results show that the PV value of the workpiece surface with a trimming of 5 mm converges to 0.04λ, and the RMS value converges to 0.005λ after modification. The research indicates that the proposed combined polishing model of the mechanical axis and virtual axis offers high accuracy and can effectively improve the processing capability of high-precision, high-gradient curved optical elements. This provides an important reference for the application of magnetorheological polishing technology in the processing of high steepness, complex curved optical elements.
WU Meng, ZHANG Qianwen, SUN Zengguo, XIANG Jiankai, GUO Ge
摘要:A fusion method was proposed to solve the problem that the single-energy X-ray cannot detect the complete decoration and disease information of the corroded ancient bronze mirror due to the uneven thickness of the mirror edge and the mirror center area. The method combined intuitionistic fuzzy set entropy measure and salient feature detection to fuse ancient bronze mirror X-ray images. Firstly, the effective guided filtering was introduced to enhance the contrast of the decorative structure of high-energy X-ray images. Secondly, a three-scale decomposition model was designed by using joint bilateral filtering and structure-texture decomposition strategy. The model extracted the energy layer, residual layer and detail layer information of different energy X-ray images. Then, the energy layer obtained the fused energy image through the rule. The residual layer used the intuitionistic fuzzy set entropy measure to construct a small-scale texture feature fusion module. And the detail layer combined the extended difference-of-Gaussians and spatial frequency enhancement operator to construct a composite saliency feature detection strategy. Finally, the energy fusion map, residual fusion map, and detail fusion map were added to obtain the final fusion result. The experimental results show that the six objective evaluation indexes AG, SF, SD, SCD, and SSIM of this method are improved by 22.19%, 22.66%, 15.01%, 44.69%, 17.07%, and 21.46% on average, respectively, compared with the other methods. The fusion results can effectively retain the clear decorative details of the ancient bronze mirror and the key features of the disease cracks. And it outperforms other comparison methods in terms of contrast and structure retention.
LI Xiongxin, XIA Fengling, ZHANG Kaomin, WANG Hongliang, XIE Tao
摘要:Haze in natural environments is usually non-homogeneous and irregular, which has a large impact on computer vision tasks. Therefore, this paper proposes Enhanced-edge-feature Dual-branch Fusion Dehazing Network (EDFDNet). In order to retain the realism of the image and at the same time effectively improve the visibility after dehazing in the case of severe blurring, the transmission graph fine branch is constructed, which is the premier branch of the network, and the U-shaped network hierarchical codec structure that fuses the discrete wavelet transform is used to extract the multi-scale fine feature information, and the mathematical method for the determination of the enhanced edge information is defined; the feature extraction branch tandemly connects the ResNet residual block and the Transformer combined with dual attention for parallel feature extraction module, which fuses the extracted local and global features, improves the network's ability to understand and process non-uniform haze images, and further restores the visibility of the images, and joins the above two branches into the backbone framework of Generative Adversarial Network (GAN), and defines a mathematical method to strengthen the determination of edge information. GAN) backbone framework to form the defogging network EDFDNet.The results of the experiments show that the average PSNR and SSIM of this method on the outdoor synthetic dataset are improved by 1.2567 and 0.0308, respectively, compared with the optimal results of the current mainstream methods.Meanwhile, in the test on the real-world dataset, the PIQE, RI, and VI reach the optimal indexes of 21.471, 0.9711 and 0.9003.EDFDNet achieves good results in both realism enhancement and visibility restoration, and is suitable for dehazing real-world non-uniform haze images.
摘要:In order to achieve cell-level operations such as cell capture, cutting, separation and injection, a flexible parallel piezoelectric positioning stage for biocellular engineering is designed, modeled, simulated and tested in this paper. The positioning stage consists of a moving platform, a base, a three-stage amplification mechanism and three piezoelectric actuators. The displacements generated by the piezoelectric actuators are amplified by the three-stage amplification mechanism, and the precise movement of the positioning stage is realized through feedback control, so as to achieve the target positioning effect. In the design process, the pseudo-rigid-body method combined with the flexible hinge stiffness calculation model is adopted to analyze the kinematic statics of the mechanism. The Lagrange equation is used to establish the dynamics model of the designed flexible parallel piezoelectric positioning stage using the lumped mass method. After determining the structural parameters, finite element analysis is carried out to verify the derived theoretical model, and the simulation results show that the error between the theoretical and simulation models is less than 10%, and the mechanism is able to achieve a large stroke as well as a higher frequency of motion. In addition, a prototype system for the flexible parallel piezoelectric positioning stage is also built and experimentally tested to evaluate its open and closed loop performance. The experimental results show that the designed positioning stage has a working stroke of 125μm×126μm, the natural frequencies in the X- and Y-direction are 128.9 Hz and 132.8 Hz, and the corresponding motion resolution are both better than 400 nm, respectively.
摘要:Aiming at the problems of unclear texture details and poor visual perception due to neglecting illumination in infrared and visible image fusion under low-light conditions, a low-light enhancement and semantic injection multi-scale infrared and visible image fusion method is proposed. Firstly, a network suitable for low-light enhancement is designed to realize the enhancement of visible image in nighttime scenes by repeated iterations of residual models. Then, a feature extractor based on Nest architecture is used as the encoder and decoder of the network, in which the deep features can capture the complex structure and semantic information of the images, a semantic prior learning module is designed to further extract the semantic information of the deep infrared and visible images through cross-attention, and a semantic injection unit is adopted to inject the enhancement features into each scale step by step. Thirdly, a gradient enhancement branch is designed, where the mainstream features are firstly passed through the hybrid attention, and then the Sobel operator stream and Laplacian operator stream are divided from the mainstream as a way to enhance the gradient of the fused image. Finally, the features at each scale are reconstructed by dense connections between the same layers and jump connections between different layers in the decoder. Experimental results show that this method improves the visual information fidelity, mutual information, disparity correlation coefficient, and spatial frequency, on average, by 23.1%, 16.3%, 18%, and 39.8%, respectively, in comparison with the nine methods, which effectively enhances the quality of fused images in low-light environments, and helps to improve the performance of the advanced visual tasks.
关键词:infrared and visible image fusion;multiscale fusion networks;low-light enhancement;cross-attention;semantic injection
CHENG Yao, WU Zhetao, SHI Xiaoyi, GONG Ao, XU Wenbing, TANG Qingtao
摘要:In order to realize the detection and control of 3D printed pieces and improve their printing accuracy, the research of 3D reconstruction of 3D parts and position estimation is completed. The system is based on the peripheral scanning visual detection principle of binocular structured light, adopts binocular structured light illumination, and takes the peripheral scanning imaging mode of dual-color camera to realize image acquisition and visual calibration through the color and infrared scene at different positions, binocular vision and scattered structured light depth information, etc. It completes the image processing and analysis, such as image fusion, point cloud coloring, multi-frame point cloud alignment fusion, segmentation, etc., so as to realize the reconstruction of object field Point cloud reconstruction. The camera position estimation scheme based on EPNP and ICP algorithms is adopted, and the EPNP algorithm completes the coarse alignment of the reconstructed object scene point cloud and single-view point cloud, while the ICP algorithm completes the fine alignment of the reconstructed object scene point cloud and single-view point cloud to obtain the position estimation of the target. The accuracy of 3D printed pieces’ 3D reconstruction is evaluated by calculating the chamfer distance between the scene point cloud and the standard point cloud, and the average accuracy is 0.675mm; the accuracy of position estimation is evaluated by the reprojection method, and the average accuracy is 1.669mm.Through the systematic research, a better evaluation method is provided for the printing inspection of 3D pieces, and a better reference is provided for the subsequent inspection and control of the accuracy of 3D pieces.
摘要:Due to the attenuation and scattering of light in an underwater environment, the images directly captured by imaging equipment suffer from significant quality degradation. Although learning-based underwater image enhancement methods improve the original image imaging quality to a certain extent, most of the existing methods use artificially synthesized or model-generated paired datasets for training. Meanwhile, there is a large domain difference between artificial or model-generated images and real underwater images in distribution, which leads to problems of excessive enhancement and no obvious removal of color shift in the enhancement results. Focus on these problems, an underwater image enhancement model that integrates domain transfer and attention mechanism has been proposed in this paper. First, an image generation network with domain transfer is designed, and combined with the physical imaging model and the water type classifier. In this way, the feature description mapping between images in different domains and scenarios could be learned, hence reducing the difference between the generated images and the real images. Furthermore, a multi-scale hybrid attention encoder-decoder network is designed. With the help of efficient feature connections and different attention fused structures, the image local details recovery ability of the model could be improved. Finally, a global domain association consistency loss function is proposed to better train the network model parameters and improve the quality of image enhancement by constructing content and structure consistent associations of the generated images at each stage of the domain transfer. The proposed model achieved accuracies of 3.1401, 0.6021 and 3.0768, 0.6124 for the UIQM and UCIQE metrics on the underwater real datasets UIEB and EUVP, respectively. The experiments show that the proposed model could effectively improve the color recovery ability of underwater images, and more details could be recovered.
摘要:The stator slot of servo motor leads to the unequal amplitude of the output signal of TMR in two orthogonal positions. Unequal amplitude affects the measurement accuracy in the position detection theory of servo motor based on time-gate technology. Based on the structural characteristics of the motor stator, a servo motor position detection method is proposed, which can effectively improve the precision of the motor rotor position detection. One pair of sensing probes are placed symmetrically and orthogonally on both sides of the symmetry axis of the stator teeth to achieve equal output signal amplitude. The other pair of sensing probes are positioned symmetrically and orthogonally at intervals of (2n+1) λi/2 (n = 0, 1, 2, 3…) degree, which can reduce the influence of harmonic components of magnetic field generated by motor stator winding. Meanwhile, waveform reconstruction method is used to eliminate the corresponding i harmonic component. Based on the above method, the signal amplitude is equal and the phase is orthogonal, which can effectively improve the accuracy. Simulation results demonstrate the effectiveness of the sensor structure based on the new error compensation method. The experimental results show that compared with the single pair probe which only satisfies the space orthogonal condition, the amplitude of the signal output by symmetrical structure sensors after compensation is equal, and the third harmonic component is reduced by 73.8%, The accuracy has been improved by 6 times. This method illustrates the obvious advantage in the accuracy of the motor rotor position detection.
LI Wenjie, LIU Wulang, WANG Beibei, HUANG, Yuyuan, LIU Guijie
摘要:Telecentric imaging has the advantages of stable magnification, large depth of field and low distortion, which has attracted much attention in the field of three-dimensional precision measurement. However, due to manufacturing limitations, the aperture stop of a telecentric lens cannot be perfectly positioned at the focal plane, allowing light rays with slight angular deviations from the optical axis to enter, thereby introducing measurement errors. To address this issue, a telecentric 3D reconstruction model based on calibration parameter correction is proposed. The theoretical analysis of the causes of telecentric optical path non-ideality leads to the construction of a system calibration parameter model related to the imaging depth, which compensates for the measurement error caused by optical path non-ideality. Based on the calibration parameters of the focal plane, the mathematical polynomial expression between the radial distortion coefficient and the imaging depth is established based on the control variable method and the least squares fitting algorithm. A random sampling consistency algorithm is employed to filter out the phase noise, and the phase-depth mapping relationship is established based on the polynomial model. During the process of three-dimensional reconstruction, the radial aberration coefficients are corrected based on the depth information determined from the absolute phase, thereby achieving high precision in the reconstruction of the lateral size. In the calibration plate and standard ball experiments, the measurement error of the measured line segment was reduced from 28.8 μm to 4.8 μm, and the measurement error of the diameter of the standard ball was reduced from 35.2 μm to 8.1 μm, thereby verifying the feasibility and necessity of the proposed scheme. This method provides an effective parameter correction idea for the precise measurement of the telecentric optical path system, and enriches the telecentric three-dimensional measurement technology.
LI Taohua, NIU Mingsheng, SHI Yongpeng, LI Hui, LIU Huiyuan, YANG Le, YUAN Haotian, FANF Hongfu
摘要:In order to improve the detection performance and integration of TDLAS detection system, A TDLAS system based on a portable adjustable optical path length cylindrical mirror multi-pass cell was designed, which achieved the simulated optical path length of 14 m, 10.6 m, 9.2 m, 7.1 m and 5.8 m. To reduce the impact of noise generated during gas measurement in TDLAS system on detection accuracy and sensitivity, the Variational Mode Decomposition (VMD) wavelet denoising algorithm optimized by the Northern Goshawk Optimization (NGO) was proposed. The simulation results showed that compared with other algorithms, the NGO-VMD wavelet denoising algorithm could effectively reduce noise without causing signal distortion. The performance of the system was evaluated by testing CH4 using a DFB laser with the central wavelength of 1.653 μm based on direct absorption detection technology. The results showed that the signal-to-noise ratio of the detection signal was increased from 66 to 109, and the lower detection limit of the system was improved from 12.1 ppm to 7.28 ppm. Allan analysis of variance showed that the optimal detection sensitivity of the system was improved from 641 ppb to 526 ppb at the integration time of 263 s after optimization with the NGO-VMD wavelet algorithm. The finding provided a reference for improving the performance of TDLAS trace gas detection system.
Zhang Jiamin, Mao Weiyun, Xiao Rong, Si Wenrong, Bian Yunyi, Hao Jia, Zhou Junzhuo, Yu Yiting
摘要:In order to improve the accuracy and efficiency of defect detection in power equipments, a time-division infrared polarization imaging system is constructed, combining a long-wave infrared detector and a polarizer. For electric transmission lines, multi-channel image acquisition is realized by controlling the polarizer rotation. Then, the polarization images with different channel numbers and different polarization angle intervals are evaluated using three parameters, i.e. root mean square error (RMSE), peak signal-to-noise ratio (PSNR) and mean structural similarity (MSSIM), respectively. The experimental results show that as the number of channels increases from 3 to 18, the image quality is gradually improved, especially in the range of 4 to 9 channels, where the improvement of imaging quality is most significant. However, further increasing the number of channels does not have a significant effect on the image quality, which leads to redundant calculations; for 3-channel polarization images, small angular intervals are able to capture the detailed information of fine targets, while large angular intervals are able to effectively separate the target from the background and reduce the noise interference, which are both suitable for some specific application scenarios. The experimental results are instructive for the polarization channel selection strategy of infrared polarization imaging.
DENG Li, ZHANG Yilian, LIU Gang, ZHANG Yue, MIAO Yuqi
摘要:MethodThe method utilizes a commonly available standard ball as the calibration object, and constructs the solution equations according to the characteristic of the ball center coordinates being constant in the robot coordinate system by changing the attitude once and translating once in a special measurement way, and solves the direction and position matrices independently by associating the solution equations in different attitudes.ResultThe experimental results show that the standard deviations of the spherical center coordinates in the X and Y directions of the two-step method are 0.3249 mm and 0.2462 mm, respectively, which are 29.5% and 61.5% higher than those of the one-step method of 0.4608 mm and 0.6391 mm, respectively. In addition, in the sphere fitting experiments, the difference between the radius of the sphere fitted by the two-step method and the nominal radius of 14.996 mm is 0.019 mm, while that of the one-step method is 0.278 mm, which is a higher fitting accuracy of the two-step method.ConclusionThe two-step hand-eye calibration method proposed in this paper significantly improves the calibration accuracy and 3D fitting accuracy compared to the one-step method.ObjetiveIn order to improve the accuracy of hand-eye calibration in the cooperative operation between line laser profilers and robots, a calibration method based on the two-step method is proposed.
SUN Xiaodong, ZHU Qibing, XU Huawei, XING Tongzhen, ZHU Haibin
摘要:Microfiber leather is a high-end composite material, and its defect detection is critical for ensuring product quality. To address the challenges posed by the multi-scale, diverse aspect ratios, and numerous small defects on the surface of microfiber leather, the MFL_YOLOv8 algorithm for surface defect detection was proposed in this study. The MFL_YOLOv8 algorithm first introduces the multi-scale feature extraction module DCNv3-LKA based on the Deformable Large Kernel Attention (DLKA) mechanism, to significantly enhances the backbone network's multi-scale feature extraction capabilities. Subsequently, the incorporation of a P2 feature map and a Dysample upsampling module in the feature pyramid network strengthens the network's ability to extract detail information from small targets. Finally, the Minimum Points Distance Intersection over Union (MPDIoU) is utilized to mitigate the inefficacy of the loss function on small targets during the initial stages of training, thus improving the detection performance for small targets. Experimental results on a self-constructed microfiber leather surface defect dataset demonstrate that the proposed algorithm achieved 92.47% of average detection precision and 92.40% of average detection recall, with improvements of 5.38% and 7.27% compared to YOLOv8n. Additionally, the algorithm attainsed a frame rate of 135.2 frames per second (FPS), meeting the accuracy and real-time requirements for industrial applications.
DU Liqun, LI Aoqi, LI Meng, YANG Xiaocheng, MENG Xiangyue, QIU HuiFeng
摘要:In order to improve the bidirectional overload capability of differential pressure sensors, a beam-archipelago dislocated membrane structure differential pressure sensitive element is designed in this paper. The sensitive element consists of a beam-archipelago silicon membrane structure bonded to a glass substrate. The beam structure reduces the stress concentration and the archipelago structure improves the structural rigidity; the glass substrate is designed with square grooves and circular through holes on the bonding surface, and the dislocation structure formed by the square grooves of the silicon membrane structure and the glass substrate further reduces the maximum stress. Firstly, the stress distribution, full scale output and maximum stress of the bi-directional high overload silicon-based differential pressure sensitive element were analyzed by finite element software. Secondly, the relationship between structural dimensions and burst pressure was analyzed, and the structural dimensions at maximum burst pressure were solved by dimensional optimization. Finally, a silicon-based differential pressure sensitive element with bi-directional high overload was fabricated by MEMS silicon process. The pressure test results show that the fabricated bi-directional high overload silicon-based differential pressure sensitive element has a burst pressure of 8.5 times scale, which is 30.7% higher overload capacity compared with the traditional C-type membrane structure differential pressure sensitive element (burst pressure 6.5 times scale). The experimental results demonstrate that the beam-archipelago dislocation membrane structure can effectively improve the bidirectional overload capacity of the differential pressure sensitive element.
YANG Jisen, XIU Fu, ZHANG Jing, YUAN Junsong, ZHANG Xiaolong
摘要:Aiming at the problem that incremental planar two-dimensional (2-D) time-grating displacement sensors need to be zeroed when they are powered up, an absolute planar 2-D time-grating displacement sensor based on multi-frequency magnetic field coupling is designed, which adopts time-driven excitation signals of different frequencies to reduce the power consumption of the sensor circuit and at the same time make the decoupling of signals in the X and Y directions and the 2-D absolute position solving simpler and more reliable. Firstly, a mathematical model of magnetic field distribution of the excitation coil is established, and the relationship between the width of the excitation coil and the height of the coupled air gap is analyzed according to the characteristics of the spatial magnetic field distribution; based on the incremental 2-D time-grating displacement sensor structure of the differential structure, an absolute planar 2-D time-grating measurement model of the opposite poles reciprocal structure is established, and a new scheme for the 2-D absolute position solution based on the look-up table method is proposed, which avoids the influence of the measurement error on the solution result in the practical application; the feasibility of this solution is verified by electromagnetic field simulation, and the optimal installation gap of the sensor is determined to be 0.8 mm; finally, the sensor prototype is fabricated, and the 2-D precision experimental platform is constructed for performance testing. The experimental results show that the sensor prototype in the effective measuring range of 147 mm x 147 mm, the original measurement errors in the X and Y directions are ±20.4 μm and ±21.1 μm, respectively, and it has the advantages of no need to find the zero point on power-on, which realizes the all-in-one 2-D absolute displacement measurement and positioning.
关键词:multifrequency magnetic field;antipolar prime;absolute two-dimensional;time-grating displacement sensor
摘要:To overcome the differences in acquisition frequency, resolution, and viewing angle between laser and camera-based speed estimation tasks in camera-LiDAR surveillance systems, this paper proposes an image-priority approach integrated with 2D-3D views for multi-target continuous tracking and speed estimation. Initially, geometrically matched feature points are uniformly selected from the scene, and the external parameters are computed using the Direct Linear Transformation method for online calibration between the LiDAR and the camera. Subsequently, a vision-guided frustum-based spatial approach for combined 2D-3D target localization is introduced. By leveraging high-resolution ground points to compute area boundaries, the method preliminarily removes background points and then adaptively calculates clustering parameters in a 2D top-down view transformed from the frustum's 3D perspective. Then, the 2D densest voxel guides the selection of the 3D initial seed point to complete clustering and localization, effectively eliminating irrelevant points and addressing the issue of mixed-resolution point cloud target detection caused by varying viewing angles. Finally, based on Kalman filtering and considering vehicle motion states, the speed estimation process is modeled as observation equations using discrete synchronized frame point cloud localization results. The observation noise covariance matrix is estimated based on point cloud resolution, enabling continuous optimal estimation of discrete speed measurements to mitigate the effects of observation noise and asynchronous timing between the two devices. Experimental results conducted on common traffic scene image and point cloud datasets demonstrate that the proposed method achieves an average absolute error of 0.2764 m/s and a root mean square error of 0.3251 m/s, with a maximum detection range of 103.211 m, indicating high accuracy and practicality.
摘要:The overseas turret-type electro optical (EO) targeting pods have been subdivided into different generations, therefore, the main technical characteristics of typical third-generation pods have been introduced. Four different evaluation criteria for measuring their integration degree have been defined: the ratio of the aperture of the optical aperture to the diameter of the turret, the cube of the aperture of the optical aperture to the weight of the system, the cube of the diameter of the pod to the weight of the system, and the ratio of the weight of the payload to the weight of the system, so as to achieve the quantitative evaluation of the functional density or technological level of the EO targeting pods of similar performances at the macroscopic level. The development status of typical equipment is introduced, focusing on the corporations of typical products such as the American MTS-B pod, Turkish ASELFLIR350 pod and the subsequent ASELFLIR400/500, Canadian MX-15D pod, French EUROFLIR410 pod and German ARGOS II HDT, etc., and their respective technical styles, characteristics and core payloads are introduced. A forward design evaluation verifies the performance of MTS-B front telescope system and ASELFLIR350 turret's optical payload. Several assimilated technical features of modern EO targeting pods are summarized: the optical-mechanical architecture of multi-band common aperture catadiopatric main system + side-axis small aperture sub-systems is gaining consensus; the laser detection technology of multiple wavelengths is increasingly inclined to the direction of active optics; composite-axis control technology based on the combination of multi-axis, multi-frame platforms and fast steering mirrors (FSM) is gaining popularity; the enhancement of target detail areas is acquiring more attention, and multi-band image fusion information processing technology is becoming more and more important.
摘要:MethodThe influence of the adding electric field with parallel direction of the axis of the fiber on the dispersion, effective mode field area, and non-linearity coefficient is simulated by using the finite element method (FEM), the evolution of optical pulse transmission in optical fiber is investigated, and the tunability of the axial electric field on the spectral width and coherence of the supercontinuum spectrum is analyzed.ResultThe results reveal that the spectral width and tunable range of the supercontinuum spectrum in the fiber with a filling factor of 0.6 is greater than that with other filling factors at the same pump. When injecting a pump pulse with a peak power of 5 kW, a pulse width of 100 fs, and a central wavelength of 3.5 μm into the fiber, the output supercontinuum spectral width reaches 2.2420 μm for an electric field strength of 40 × 108 V/m, an increase of 176.30 nm over that without the electric field. As the adding electric field causes the coherence factor of the supercontinuum to converge to 1 at longer wavelengths, it also contributes to the coherence of the supercontinuum.ConclusionMid-infrared supercontinuum light sources with continuously tunable spectral width can be obtained and have potential applications in fields such as sensing detection and biomedicine.ObjetiveIn order to make the spectral width of the mid-infrared supercontinuum spectrum continuously tunable, a chalcogenide photonic crystal fiber (PCF) with As2S3 matrix material and LiNbO3 crystal auxiliary rods, whose optical axis is running along the axial direction of the fiber, is proposed.
摘要:To realize the high-precision command tracking control of the piezoelectric platform, an adaptive fractional order sliding mode tracking control method is proposed in this paper to address the serious hysteresis problems. At first, the fractional order operator and adaptive law based on the Duhem model are introduced into the design of the sliding mode surface. It increases the degree of freedom variability of the sliding mode surface and achieves the adaptive adjustment of parameters. Next, an uncertainty and disturbance estimation technique is proposed to replace the traditional switching term of the sliding mode controller, which solves the chattering problem of the sliding mode controller and improves its robustness. Finally, the experimental results of the command tracking control of the piezoelectric platform show that compared with traditional PID and sliding mode control method, the tracking error of the adaptive fractional order sliding mode controller has decreased by more than 80%, and the root mean square tracking error of the piezoelectric platform based on adaptive fractional order sliding mode controller is reduced to 0.41μm under the reference command signal at 50 Hz. Therefore, the adaptive fractional order sliding mode controller has more superior tracking performance.
关键词:Piezoelectric platform;Hysteresis nonlinear;Adaptive control;fractional order;sliding mode control