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Issue 6 ， 2007
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Precision measurement scheme for beat-length of polarization maintain optical fiber
Abstract：A precision measurement scheme for beat-length of polarization maintain optical fiber was proposed based on optical coherence domain polarimetry, and the beat-length of polarization maintain optical fiber with different structures and sizes was measured. The principle of optical coherence domain polarimetry was demonstrated and the beat-length measurement equation was derived. A measurement system was setup by modifying the Michelson interferometer and precision measurement was achieved with the modulation and demodulation technology. The error analysis shows that the measuring error is less than 0.01 mm. The performance including accuracy and repetition was investigated with this system, the beat-lengths of 8 types of polarization maintain optical fibers with different structures and sizes were measured, the result shows that the accuracy and repetition of beat-length measurement are both better than 0.01 mm.Keywords：optical coherence domain polarimetry;polarization maintain optical fiber;beat-length measurement- 45
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Published：2020-08-12 -
Profile measurement for micro-varying liquid surface based on chessboard grating Ronchi test
Abstract：Based on chessboard grating Ronchi test,a micro-varying surface profile measurement method was proposed, which can measure the slopes in two orthogonal directions of the surface simultaneously for reconstructing the surface profile by only one deformed chessboard grating pattern. Information of the two orthogonal directions in deformed chessboard grating patterns can be effectively separated and extracted through simple differential operation and extremum tracking. Based on the proposed method and the data extraction algorithm, a micro-varying surface profile measurement system was built up to measure a stationary surface and a varying surface. The results show that the system meets the measurement need of micro-varying liquid surface in some research fields with its resolution less than 0.1 μm and measurement range more than 50 μm.Keywords：chessboard grating;Ronchi test;surface profile;image processing- 67
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Published：2020-08-12 -
Design and optimization for shape of space membrane mirror
Abstract：On analysis of the mechanics theory of polyimide membrane mirror, a numerical solution of membrane reflector on the equispaced load and proper pre-stressing force is computed, and the error between ideal surface and computed surface is given. Taking surface load on different areas of the mirror as design variable, yield strength of the membrane as state variable and mean square root of the error between ideal surface and computed surface as target function, the surface shape of membrane mirror is optimized with ANSYS software. Finally, the wavefront of the mirror before and after optimization is calculated using Zernike polynomial fitting, and aberration of the mirror is presented. The results show that the shape of high accuracy parabolic membrane mirror can be obtained applying appropriate loads on different areas of the membrane mirror.- 65
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Published：2020-08-12 -
Characteristics and application of elliptical curved LiF crystal analyzer
Abstract：Based on the principle of elliptical focusing, an X-ray elliptical curved crystal analyzer whose measurement range,focal length,eccentricity and Bragg angel range are respectively 0.6~6 keV,1350 mm,0.9586 and 30°~60° was designed for investigating the laser producing plasmas. Aimed to the characteristic study of a high density plasma,a experiment was carried out with laser length of 0.35 μm,power of 1.6×1014 W/cm2,and the incident angel on the Ti plane of 45°. The result shows that the sensitivity of elliptical curved LiF crystal has very good detection ability,its calculated wavelength resolution is about 500~1 000 in the range of 0.2~0.35 nm. Experimental results also show that the curved crystal analyzer can be used in spatial resolution measurement for aplanatic property,its sensitivity is higher than a flat crystal. It suggests that curved LiF crystal analyzer is suitable for plasma diagnostic.Keywords：Crystal spectrometer;crystal analyzer;plasma diagnosis;integrated reflectivity- 57
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Published：2020-08-12 -
Design of electrostatic lenses in nanometer scale focusing ion beam system
Abstract：A new focusing system was designed by optimizing its optical properties in different beam currents and energies. Damped least square method was used to design a single lens and lens system.The single lens was designed through combination of separating and assembling, and the ratio of aberration coefficient and focus length at infinite magnification was chosen as the objective. Both optical properties and practicability were considered when choosing the working modes between lenses. Collimated mode was used in the larger beam current while crossover mode was in the smaller one. Axial aberration and magnification were the objective in bigger beam current and in the smaller one respectively when optimizing the two lenses. The results show that the resolution is 31.52 nm (the magnification is -0.539 095 5 and the aberration is 16.33 nm) and 4.73 nm (the magnification is 0.084 359 9 and the aberration is 2.15 nm) under beam current of 2 nA and 2.5 pA. The lens system can work under different beam energies when adjusting the potential on the second plane and the space between the second plane and the third plane of the lens 2, which will enlarge its applications, and the etching, deposition, implantation and imaging can be realized in the same system.Keywords：focusing ion beam;electrostatic lens;damped least square method;working mode;current density contours- 40
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Published：2020-08-12 -
Propagation and self-imaging effect of deformed high-order Bessel beam
Abstract：Based on the typical arrangement for generating high-order Bessel beam and decomposing it into high-order Bessel cosine beam and high-order Bessel sine beam,the analytical expression of a deformed high-order Bessel beam and its propagation properties in self-focusing lens were analyzed using the Collins formula in cylindrical coordinate system. The general analytical expression of the deformed high-order Bessel beam and its propagation properties of in self-focusing lens self-imaging process in free space were obtained. The numerical simulation results were also given, when the difference of transverse component of wave number between high-order Bessel cosine beam and high-order Bessel sine beam was 0.005 K. Experimental results show that the deformed high-order Bessel beam is still nondiffracting beam with self-imageing effect in free space.Keywords：deformed high-order Bessel beam;self-imaging;self-focusing lens;light propagation- 47
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Published：2020-08-12 -
Mach-Zehnder interferometry for detecting side cooling uniformity of laser medium
Abstract：For detecting side cooling uniformity of laser medium, a detecting method based on Mach-Zehnder interferometer is presented. Theoretical analysis indicates that the interference fringe produced by a reference beam and a beam passing the medium is also isotherm on the radial face of the laser medium. The simulations on the temperature fields of uniformly and non-uniformly cooled mediums by heat analysis software indicate that: if the interference fringe is circle with the center of the radial face as the center, the sides of the medium contact closely with the copper cooler, the medium is cooled uniformly. If the interference fringe is distorted to a certain direction, the medium contacts loosely with the copper cooler in the direction. In the experiment, a distorted interference fringe is obtained by detecting a 3 mm×3 mm×5 mm sized, a-cut, 0.5% Nd3+ -doped Nd:YVO4 embedded in a copper cooler. A circular interference fringe is obtained after reassembling the copper cooler according to the distorted direction of the distorted interference fringe. Experimental result agrees with the theoretical analysis very well, it has proved that Mach-Zehnder interferometry can detect side cooling uniformity of laser medium.Keywords：Mach-Zehnder interferometry;laser medium;calorescence effect;side cooling- 54
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Published：2020-08-12 -
Real-time error-correction method for photoelectrical theodolite
Abstract：After analyzing the source and effect of measuring error, all the system errors of a photoelectric theodolite were obtained with means of shooting star,based on which, programs to fulfill the real-time error-correction for the photoelectrical theodolite's measuring result were given. The measuring data from a certain kind of photoelectrical theodolite were corrected using the proposed method. Through comparing the measuring precision before and after error-correction, the results indicate that this correction method can improve photoelectrical theodolite's measuring precision from about 15″ to less than 5″;that is to say the correction effect is obvious enough to prove that the method has achieved the expectant purpose.Keywords：photoelectrical theodolite;measuring error;measuring precision;axis error- 56
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Published：2020-08-12 -
Design of composite flywheel rotor
Abstract：A design method of flywheel rotor consisting of composite rim and metal hub is given considering connection between rotor and driving machine. The influence of the factors such as the material, configuration, connection and facture technics of rotor on the energy density is analyzed. In the result, the ratio of inner radius to outer radius of rim is a key factor for energy density, which is determined by rim material. Optimizing hub can also further improve the energy density. Due to the theory value of composite and the mechanic constant of glue is not exact, it has been revised via the experiment for improving the veracity of emulational results. A composite flywheel rotor is produced, moreover, the rotate stress testing is carried on the speed of 20 000 r/min. The results of emulation are consistent with test, it is proved to be right of the design method on the paper.Keywords：composite material;flywheel rotor;energy density;simulation analysis- 42
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Published：2020-08-12 -
Proof-phase-margin design of nutation cross-feedback control in magnetically suspended high-speed rotor system with large rotary inertia
Abstract：A parameter design method of nutation cross-feedback control is investigated. Based on nutation stability analysis of a large-inertia and high-speed rotor using two-frequency Bode diagram, a new proof-phase-margin method of cross-feedback parameter design based on two-frequency Nyquist contour is proposed. The proportional coefficient and High-pass Filter (HPF) cutoff frequency of cross-feedback are determined by vectors combination to accomplish the robust design of nutation stability. Utilizing designed cross-feedback controller, nutation stability of rotor in the magnetically suspended control moment gyroscope is significantly improved and the critical speed of rotor increases from 10 500 r/min to 20 040 r/min. It can be concluded that the proposed method is effective for cross-feedback parameter design, which provides important foundation for rotor suspension stability of control moment gyroscope and momentum flywheel.Keywords：magnetic bearing;gyroscopic effect;nutation;stability;cross-feedback control;two-frequency Nyquist contour- 55
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Published：2020-08-12 -
Micro electromagnetic actuator with high energy density based on MEMS technology
Abstract：A fabricating technology for high energy density micro electromagnetic actuator based on Micro Electron Mechanics System(MEMS) is introduced. The main steps on MEMS technology are as follows: Firstly, etching plating trenches of multi-turn double planar microcoils and permalloy (NiFe) core into silicon wafers prior to electrode position, a seed layer of copper must is deposited on the wafer; secondly, when the thick of seed layer reaches to about 20 μm by electroplating, peeling the surface plating on the wafer and coating the core by photoresist, electroplating the coil in the groove; thirdly, when the coil groove is filled with copper, coating the coils and electroplating permally core. In the 10 mm×10 mm×0.38 mm square silicon wafer, a high energy density electromagnetic microactuator, composed of multi-turn double planar microcoils (22×2 turns, section of copper wire is 60 μm×60 μm, length is 1 164 mm) and permalloy core (3 mm×3 mm×0.2 mm), is fabricated. Finally, the estimated force produced by the integrated electromagnetic microactuator is around 50 mN at a sinusoidal current amplitude of 0.3 A, which is fabricated and tested on the valveless micropump. Experiment results show the microactuator is efficient in producing large magnetic force and flexible in application.Keywords：MEMS;micro electromagnetic actuator;high energy density;multi-turn double planar microcoils;thick permalloy plating- 51
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Published：2020-08-12 -
Dynamic performance of inchworm-type piezoelectric linear actuator
Abstract：The structure and working principle of a inchworm-type piezoelectric linear actuator are analyzed, and the mechanical system dynamic modal of the actuator is established. Based on the analysis of the actuator's stator, the output performance of proposed actuator is analyzed,experimental results show that the output displacement of the actuator is stable, and the displacement for single step is 9.8 μm when the actuating voltage is 100 V. The velocity and acceleration properties of the linear actuator are tested. According to the testing results, the dynamic response performance of the actuator is analyzed deeply. The experimental results show that the proposed piezoelectric linear actuator has good dynamic performance and motion stability.Keywords：piezoelectric actuator;inchworm motion;precision position;linear motion;dynamic performance- 61
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Published：2020-08-12 -
Design of state feedback control system for spherical robot based on state observer
Abstract：The dynamic equation of a spherical robot was established,and a nonlinear affine system is derived based on energy dissipation Lagrangian equation. Linearization and affine transformation methods are used in the new equilibrium point to design control system by a powerful linear theory, according to the actual movements and theoretical simulated datum of robot. A state observer is built for estimating full state variables of system in real-time because some of state variables are immeasurability. The state feedback controller is designed and the simulation results prove the validity of the controller.Keywords：spherical robot;energy dissipation;affine transformation;state observer;feedback controller- 50
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Published：2020-08-12 -
Micro-displacement magnifying mechanism used in piezo-stack pump
Abstract：A micro-displacement magnifying mechanism used in piezo-stack pump is presented. Taking the piezoelectric multilayer actuators as drivers of amplifier,the displacement of piezoelectric multilayer actuator is amplified with the flexure hinge amplifier based on the principles of triangle amplification. The static and dynamic characteristics are tested on the prototype,the characteristics of good linearity, high resolution and high frequency are approved.Experimental results conclude that the mechanism can amplify the displacement to 5 times. The natural frequency reaches 1.8 kHz by finite element analysis while the actual measurement result is 1.5 kHz.- 36
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Published：2020-08-12 -
Comparison of evaluating precision of straightness error between least square method and least envelope zone method
Abstract：The algorithm model and the realization method of evaluating straightness error in least squares method and least envelope zone method were introduced in detail. The experimental data of eight different kinds of straights were obtained on Coordinate Measuring Mechine(CMM). Then the measured data were evaluated by least square method and least envelope zone method based on search approximatioss (namely cut and try method in revolutionally). The experimental results indicate that the two methods are completely consistent and the evaluated result of straightness error by least square method conforms to the least condition.Keywords：straightness error;evaluation;least square method;least envelope zone method- 40
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Published：2020-08-12 -
Micro-milling machine tool, micro-tool wear and cutting forces in micro-machining
Abstract：The system construction of a 3-axis precision micro-milling machine tool with overall size 300 mm×300 mm×290 mm was presented. The control software package integrated with a video collecting system in Chinese was developed to facilitate users' operation. This micro-milling machine tool has been successfully used in manufacturing a micro-groove in film work piece (the film thickness is 65 μm, material removal rate of the micro-groove along the film thickness is 90.7%, surface roughness of the bottom of the micro-groove is 0.365 μm, and the yield is more than 80%). Furthermore, the experiments with the TiAlN coated and uncoated carbide micro-end-milling tools were carried out to analyze the mechanical characteristics and wear mechanism of the tool. Finally, the effects of cutting parameters (spindle speed, cut depth and feed per tooth) on cutting forces were discussed. The works mentioned above are the foundation of next research on the mechanism of micro-end-milling.Keywords：micro-milling;micro-milling machine tool;tool wear;cutting force- 42
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Published：2020-08-12 -
A novel differential piezoelectric accelerating sensor
Abstract：A novel differential piezoelectric acceleration sensor was introduced. The sensor's structure and operating principle were presented and its mathematic model was established, then the relationship between the sensor's output characteristic and inertial mass and the piezoelectric components was discussed. Finally,the process circuit structure of sensor and its characteristic were discussed also. Experimental results show that the sensor with one inertial mass can realize the differential measurement of acceleration signals, and it has advantages in simple structure, light weight, simple for working and manufacturing, and better anti-interference ability. Its linearity is up to 0.1%, which is half of common accelerometer. It has satisfied the design purpose in frequency response error of 1% and repeatability of 1.27%, and its measurement sensitivity is twice of general accelerometer.- 73
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Published：2020-08-12 -
Cancellation of nonlinear error of bridge using op amp feedback control
Abstract：A method to reduce the nonlinear error of a bridge using operational amplifier (op amp) feedback were introduced,the feedback conditions of canceling nonlinearity were found by circuit analyzing. Ignoring input bias current and input noise voltage of op amp in four linearity circuits,the output expressions for affect of offset voltage on measuring system were given.The correction characteristic of each method was analyzed to attain optimal testing bridge circuit to reduce the errors of offset and drift by five times. The results show the method can provide a theory guidance for choosing op amp and determining method in bridge circuit measuring system.Keywords：Bridge;op amp;nonlinear error;offset voltage;feedback control- 32
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Published：2020-08-12 -
Parameter prediction of bending of aluminum alloy sheet induced by laser prompt heating
Abstract：Based on the basic platform of BP neural network, a BP network model was founded to predict the bending angle in the process of laser bending of aluminum alloy sheet to optimize laser bending parameter control. The sample data obtained from experiment were used to train BP network. The nonlinear regularities of sample data were fitted through trained BP network, the predicted results include laser bending angles and laser bending parameters. Experimental results indicate the prediction allowance is controlled less than 5~8 %,it can provide effective foundation both theory and experiment for industry purpose.Keywords：precise shaping;laser heating;laser bending;aluminum alloy sheet;parameter prediction- 45
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Published：2020-08-12 -
Research on vibration and pump flow rate of valveless piezoelectric pump with Y-shape tubes
Abstract：In order to meet the needs of transporting cells and macromolecules in such areas as medical mechanism, sanitation and health care, a new type of piezoelectric pump, the Valveless Piezoelectric Pump with Y-shape Tubes(VPPYT), is presented and its vibration and pump flow rate are analyzed. The structures and characteristics of VPPYT and its tubes are introduced firstly. Then, based on the bending vibration theory of thin circular board, the vibration of the piezoelectric actuator is analyzed theoretically. After that, through analyzing the fluid state in VPPYT and its tubes, the equation for the calculation the pump flow rate is established. Finally, Finite Element Method (FEM) is employed to simulate the flow state in the Y-shape tubes to obtain the flow resistances and pressure variation rules along the positive and negative directions, respectively. The experimental results show that the theoretical and experimental pump flow rates follow the same variation trend, and the minimum relative error between the two results is 12%. Thus the validity and correctness of the theoretical analysis and the numerical simulation are proved.Keywords：piezoelectric pump;flow resistance Y-shape tube;vibration analysis;flow rate calculation;FEM- 36
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Published：2020-08-12 -
A low power wireless infrared video transmission system
Abstract：A low power wireless infrared transmitting system is presented for transmitting video signal. Using anti-fuse FPGA devices as Encoding/Decoding (ENDEC) core, and high speed serial infrared transceivers as transmission module in this system, the run length limited (RLL) code is deployed in FPGA as a channel ENDEC module to work together with other modules, including IO buffer, serializer/deserializer, cycle redundancy checksum and scrambler/descrambler. Combined with AD/DA interface circuits, these modules compose an integrated demonstration system, in which the two-channel composited video signal can be orderly captured, encoded, emitted, decoded and displayed.The transmitting bandwidth of the system is up to 16 Mbit/s, but the power consumption of the infrared emitting module is low to 500 mW. Therefore it can be used as a wireless interface between the video capture equipment and the video processing system.Keywords：wireless infrared transmitting;anti-fuse FPGA;low power design- 65
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Published：2020-08-12 -
Low power image fusion system based on Virtex-4 FPGA
Abstract：In order to reduce the power consumption of image fusion system based on FPGA, the main factors impacting on the system power consumption were introduced. Then the low power designs of main modules in the system were analyzed in detail, including power module, outer memorizer, FPGA device and so on. The Virtex-4 SX35 FPGA equaling to a device of three million logic gates produced by Xilinx for high-performance signal processing was selected, and TPS54310 and TPS54610 with low power character,and adjustable output voltage of 0.9~3.3 V and accuracy of 1% designed by TI were used to produce the main system power. ZBT SRAM was chosen for outer memorizer to realize unlimited true back-to-back read/write operations without waiting states,it can dramatically improve the throughput of data in system, especially when it requires write/read transitions frequently. With the characteristics of fusion algorithms and the advantages in resource and technology of Virtex-4 FPGAs, the particular low power design was discussed around such techniques as bus coding, pipeline design and parallel processing, etc. The analytic conclusions indicate that the real power consumption of the system can be reduced effectively and its reliability can be guaranteed if the foregoing designs are adopted properly.Keywords：FPGA;image fusion system;Virtex-4;low power- 26
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Published：2020-08-12 -
Hardware design of infrared dim target real time detection and tracking system based on multiple ADSP-TS201S
Abstract：The hardware design of a real time infrared dim target detection and tracking system was introduced and the signal processing module in this system was presented in detail. Using 600 MHz high performance digital signal processor produced by the Analog Device Company, four pieces of ADSP-TS201 were coupled loosely to constitute a parallel processing module. The computational performance of this module can be up to 19.2 GMAC(16bit) per second in fixed-point operation and 14.4 GFLOPS in floating-point. This module affords a hardware flat to the real time detection and tracking of serial weak and small infrared targets.Keywords：ADSP-TS201;infrared dim target;target detection;target tracking- 32
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Published：2020-08-12 -
Motion-stereo double matching restriction in 3D movement analysis
Abstract：In order to realize the correspondence of arbitrary object side feature points of moving object in the different time in three-dimensional (3D) movement analysis, motion-stereo image matching in the process is studied. A algorithm of double matching restriction and motion-stereo image of matching is presented. The basic image matching based on point feature is completed by correlation coefficients and relaxation algorithm,and the feature point correspondence of movement object is performed by motion-stereo double matching restriction of binocular sequence image. A set of experiment results are presented,it shows that the accuracy of the final correspondence is about 76.5%,which can meet the requirements of the 3D motion object tracking and locating the feature points.Keywords：image matching;sequence image;3D motion analysis- 29
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Published：2020-08-12 -
Detection of surface cracks of corn kernel based on morphology
Abstract：The surface crack identification and detection of a corn kernel are studied based on digital image processing. Cold Cathode Fluorescent Lamps(CCFL) are chosen to construct the image capturing illumination environment, and a set of image acquisition system of the corn kernel is established. Then, a surface crack detection method is developed based on morphology of the corn kernel. A binary image including the cracks, boundary and noises is picked up with horizontal and vertical Sobel operators. Then, a majority of non-crack information is eliminated by image subtraction after finding the tip of the corn kernel using its morphology. Finally, the cracks are extracted and the absolute and relative lengths of cracks are calculated according to the crack length and position. A detecting experiment is carried out by 50 kernels with cracks and 50 kernels without cracks selected from NongDa-4967 and NongDa-3138 (two novel varieties of corn seed developed by China Agricultural University) respectively. The results indicate that the detecting accuracy are 94% and 90%. It can meet the requirement of the accuracy of surface crack detection of corn kernel.Keywords：computer vision;image processing;corn kernel;surface crack;morphology- 92
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Published：2020-08-12 -
Vision-based low altitude tracking system
Abstract：A vision-based low altitude tracking system mounted on an unmanned aerial vehicle is established. The system is composed of ground station and on-board module, and constructed two parallel control loops: automatic tracking control loop and manual intervening control loop. The multi-threshold segmentation algorithm with adaptive tolerance based on gray-level histogram is presented,and a object dynamic clustering algorithm with double sub-windows is analyzed. The pan and tilt head are controlled based on the miss distance of the object centroid. The system can switch smoothly from one control loop to another as the miss distance is replaced by the coordinates of the mouse relative to the center of the monitor view. The motion is segmented even in the shade by several appended thresholds for varying illunination. The object centroid position is obtained correctly through 2~3 iterations in the process of dynamic clustering, and the disturbance of other objects is removed. The system can produce good tracking results at a frame rate of 15 frame/s. The results show that the algorithms and methods are available, and the system has a certain extent practicability.Keywords：low altitude tracking;parallel control loop;multi-threshold segmentation algorithm;double sub-windows;dynamic clustering;miss distance- 42
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Published：2020-08-12 -
Adaptive regulation of CCD camera in eye gaze tracking system
Abstract：An eye-gaze tracking method and an automatic adjusting method for object lens of CCD camera in combining the aperture regulation with zooming and focusing are proposed by analyzing the geometrical positions of two LEDs,a camera,an eye cornea and its glints. The aperture of CCD lens is controled to adapt the system to external lighting circumstances based on the average brightness values of the processed images.A SMD operator is used for focusing roughly and quickly in a large scale for obtaining the eye glints to control a pan-tilt unit for eye aiming and eye tracking,and regulating the focus of the lens to locate the eye and adapt the head movements in a head-shoulder image. The FSWM operator is applied in the determined window in the eye region to focus automatically for getting clear images. If the pupil can be extracted from the image, the average gradient of the edge points of the pupil can be used for real-time focusing. Experiments show that this system can track the eye and acquire clear eye images in real time by the adaptive regulation of the CCD camera in different external lightings and user position conditions.Keywords：eye-gaze tracking system;CCD camera;adaptive regulation;automatic focusing;eye tracking- 32
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Published：2020-08-12 -
Solution of small sample size problem in face recognition using Gabor wavelet transform
Abstract：A novel algorithm for solving the small sample size problem in face recognition is proposed. The size of each face sample is increased greatly and the small sample size problem is resolved by regarding every Gabor wavelet transformed output image as an independent sample. A special nearest neighbor classifier using whitened cosine distance is designed for the classification of face feature vector groups. The experiments comparing the prosposed approach with the direct PCA method in FERET face database show that the average correct face recognition rate of the proposed algorithm can reach 97%, which is superior to the direct PCA method.Keywords：face recognition;Gabor wavelet transform;small sample size problem- 51
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Published：2020-08-12 -
Influence on polarization independence of frequency selective surface by altering Y slot element arrangement
Abstract：A novel polarization-independent Frequency Selective Surface(FSS) is designed by altering traditional Y slot element arrangement. Based on the modal matching method, the frequency response of this structure is analyzed to obtain the plot of frequency versus transmission coefficient. With coating technology and lithography, the FSS samples of conventional and improved arrangement are made respectively. The tests under different polarized waves at 30° incidence angle are given in the microwave darkroom. The measured curve shows good agreement with the simulated curve. Both of the numerical analysis and experiment results show that the response of FSS with the conventional arrangement is changed very distinctly with the source polarization, the increase of transmission loss is -1.09 dB; but with the modified structure, the increase is only -0.25 dB. The improved Y element array can be resonant at a single frequency and has good polarization independency. It provides a new design method for that the polarization situation of a source is completely unpredictable.Keywords：FSS;polarization independence;frequency response- 51
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Published：2020-08-12 -
Application of model reference adaptive sliding mode control to forward compensation system in camera
Abstract：In order to improve the flight resolution of a aerial camera, a new Model Reference Adaptive Sliding Mode Control (MRAC-SMC) solution is presented. The model reference adaptive algorithm is used to identify time-variant system parameters and modify switching function of sliding mode controller,and the variable rate reaching law based on attenuation control is taken as the switching function of SMC to quicken the convergence in system and reduce the chattering caused by switching. The experiment results indicate that the velocity compensation error can be reduced by 60% and accordingly flight resolution can be increased by 200% by MRAC-SMC compared with PID control. Therefore, forward image motion compensation system based on MRAC-SMC can improve velocity tracking accuracy and robust performance and can overcome the effect of uncertain time-varying forces also.Keywords：Adaptive control;sliding mode control;image shift compensation;variable rate reaching law;uncertain time-varying disturb- 25
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Published：2020-08-12 -
Application of correlation analysis to parameter recognition for blur image
Abstract：A practical method for estimating the blur parameters using correlation analysis is proposed. In the frequency domain the correlation between the original blurred images and the second blurred images is analyzed after blurring the original images by a series of Point Spread Functions(PSFs) with various parameters of same model. The experimental results indicate that the algorithm is suitable for the parameter recognition of both defocus and motion blur models and has higher precision and less computational cost.Keywords：PSF;blur image;defocus blur;motion blur;correlation- 30
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Published：2020-08-12
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