Journals >Optics and Precision Engineering
Contents
2009
Volume: 17 Issue 9
38 Article(s)
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Research Article
FBG strain sensor based on online forming
LI Jian-zhi, DU Yan-liang, and LIU Chen-xi
To eliminate the temperature effect of Fiber Bragg Gratings(FBGs),a new thermal stress compensation mechanism and an online-forming technology are presented to design and manufacture a novel FBG strain sensor. The sensor can not only compensate temperature drifts,but also can enhance the stain sensitivity,so the weak aTo eliminate the temperature effect of Fiber Bragg Gratings(FBGs),a new thermal stress compensation mechanism and an online-forming technology are presented to design and manufacture a novel FBG strain sensor. The sensor can not only compensate temperature drifts,but also can enhance the stain sensitivity,so the weak adhesion and glue aging in packaging processing is improved. Especially,the sensor can be used in the stress measurement that can not be realized by traditional temperature compensating sensors. The experimental results indicate that the sensor provides good abilities of temperature compensation and strain sensitivity in 20-40 ℃. In measurement ranges,it shows a near zero shift and a high strain sensitivity of 1.69 pm,which is 1.4 times that of bare FBGs in the proposed self-compensated package and is coincident with the theoretical calculation well. These results prove that the sensor resolves some difficulties existed in optical fiber sensing fields,for it has temperature compensated functions and strain-testing functions simultaneously..
Optics and Precision Engineering
- Publication Date: Sep. 20, 2021
- Vol. 17, Issue 9, 2069 (2009)
Experiment system of 400 mm thin-mirror active optics
LI Hong-zhuang, Lin Xu-dong, LIU Xin-yue, WANG Fu-guo... and HAN Chang-yuan|Show fewer author(s)
An active optical experiment was carried out by a mirror with a diameter of 400 mm and a thickness of 12 mm. The support construction of the mirror included 12 active supports and 3 fixed supports,in which the active support was implemented by force actuators consisting of piezoelectric ceramic actuators and loadcells.An active optical experiment was carried out by a mirror with a diameter of 400 mm and a thickness of 12 mm. The support construction of the mirror included 12 active supports and 3 fixed supports,in which the active support was implemented by force actuators consisting of piezoelectric ceramic actuators and loadcells. The active supports were used for controlling the surface of the mirror,and the fixed points were used for positioning the mirror. In the experiment,the mirror surface was tested by a Zygo interferometer. The surface error of the mirror was tested before and after an actuator exerted a unit force on it lonely,then the difference between the two surface errors was calculated to be as the response function of the actuator,and the response functions of all the actuators made up a stiffness matrix. Afterwards,the damp least square method is used to determine the active corrective force and the process of exerting force of the actuator was controlled by a PID arithmetic. The experimental results show that the surface error is corrected from 1.22λRMS to 0.12λRMS,which is close to 0.1λ that is the surface quality after polishing. The experiment shows the active correct arithmetic and procedure is correct and feasible..
Optics and Precision Engineering
- Publication Date: Sep. 20, 2021
- Vol. 17, Issue 9, 2076 (2009)
Illumination system design for ocular wavefront aberration measurement
ZHANG Pei-ming, CHEN Jia-bi, YANG Xue, and XIE Hai-ming
A kind of automatic and adjustable illumination system was designed to improve the poor precision in the measurement of strong ocular aberration of human by a narrow parallel beam illumination.By adding a position adjustable collimation lens in the light path,the diopter of illumination light source could be precisely A kind of automatic and adjustable illumination system was designed to improve the poor precision in the measurement of strong ocular aberration of human by a narrow parallel beam illumination.By adding a position adjustable collimation lens in the light path,the diopter of illumination light source could be precisely controlled by adjusting the lens,and the position of collimation lens could be exactly and rapidly scanned and located by a motorized stage. Moreover,the aberrations of a model eye are measured by the narrow parallel beam illumination system and by the adjustable illumination system in this experiment respectively. The obtained results show that the Peak Signals to Noise Ratio(PSNR) of the image got by the sensor in the automatic and adjustable illumination system are improved from 5.72 dB to 19.89 dB,and the average defocuses of a -5 m-1 model eye is changed from -(4.285±0.208) m-1 to -(5.041±0.157) m-1 as compared with that of the narrow parallel beam illumination. These data show that the PSNR of the image for Hartmann-Shack sensor has been obviously improved by the automatic and adjustable illumination system,which makes the measurement result more accurate..
Optics and Precision Engineering
- Publication Date: Sep. 20, 2021
- Vol. 17, Issue 9, 2084 (2009)
Alignment for center distance of optical telescope in satellite optical communication terminal
YU Jian-jie, TAN Li-ying, LIU Jian-feng, HAN Qi-qi, and YANG Yu-qiang
The optical telescope of satellite optical communication terminal is composed of an objective and an eyepiece,and the axial center distance of the two lenses has an important influence on emitting and receiving performance of the system. The digital single-wavelength interferometer is an effective device to measure andThe optical telescope of satellite optical communication terminal is composed of an objective and an eyepiece,and the axial center distance of the two lenses has an important influence on emitting and receiving performance of the system. The digital single-wavelength interferometer is an effective device to measure and adjust the axial center distance,however,it is usually difficult to be determined precisely when there is a wavelength difference between the interferometer and the optical telescope,because the focal length difference of the objective and the eyepiece varies with the wavelength. In this paper,the relation between the variations of center distance and the corresponding interference fringe counts was deduced on the basis of eikonal equation,then an efficient alignment method was given according to the relation. Several proof schemes including experiments and numerical simulation were suggested,and the second scheme was chosen to verify the alignment method presented in this paper. Numerical results show that the alignment error of center distance in a Cassegrain reflective optical telescope is less than 15%,and that in a refractive optical telescope is only about 3%. These results show that the proposed method can meet the alignment requirement of the satellite optical communication terminal..
Optics and Precision Engineering
- Publication Date: Sep. 20, 2021
- Vol. 17, Issue 9, 2091 (2009)
Mathematical modeling and calculation on exposure time of curtain-type shutter
ZHANG Lei, DING Ya-lin, and JIANG Gui-de
To determine the relationship between the size parameters and the exposure accuracy of a curtain-type shutter,the expression of exposure time is calculated,and the mathematical model of exposure accuracy is established according to the principle of the curtain-type shutter and its exposure time. Then,the main factors iTo determine the relationship between the size parameters and the exposure accuracy of a curtain-type shutter,the expression of exposure time is calculated,and the mathematical model of exposure accuracy is established according to the principle of the curtain-type shutter and its exposure time. Then,the main factors impacting the exposure time accuracy are analysed,and the error for every parameter is calculated with an error synthesized method.Finally,by taking an aerocamera as an example,the exposure accuracy is worked out. The experiment results indicate that the slit width on the curtain-type shutter is proportional to exposure time between 1/1 000~1/100 s,and the exposure time accuracy is increased with the slit width. The minimum exposure time accuracy of the shutter in the camera is 6.4%,which is higher than the accuracy of 8.59% calculated by the theory. The error influenced by the slit width is 3.6 times that influenced by the velocity..
Optics and Precision Engineering
- Publication Date: Sep. 20, 2021
- Vol. 17, Issue 9, 2098 (2009)
Preparation and analysis of UV-enhanced Zn2SiO4:Mn films for image sensors
NI Zheng-ji, LIU Meng, ZHANG Da-wei, HUANG Yuan-shen, and ZHUANG Song-lin
In order to enhance the UV-response of CCD & CMOS detectors, Zn2SiO4:Mn phosphor with the properties of small particle sizes,well-stabilizing and high-luminescence quantum efficiencies was chosen as a film material to be coated on the surface of a CCD or a CMOS. The Zn2SiO4:Mn thin-film on quartz substrates was preIn order to enhance the UV-response of CCD & CMOS detectors, Zn2SiO4:Mn phosphor with the properties of small particle sizes,well-stabilizing and high-luminescence quantum efficiencies was chosen as a film material to be coated on the surface of a CCD or a CMOS. The Zn2SiO4:Mn thin-film on quartz substrates was prepared by the spin-coated method. The transmission spectrum,absorption spectrum,excitation and emission spectra of the Zn2SiO4:Mn thin-film were measured. The results indicate that the thin-film has stable low transmission and high absorptivity when the waveband of illuminated light is less than 300 nm. Moreover,the excitation peak of the film is 260 nm and the emission peak is 525 nm,which is at the sensitive respond band of the CCD. Meanwhile,this experiment analyzed the effects of the thickness,smoothness and stability of the Zn2SiO4:Mn thin-film on the frequency properties,the results show that the Zn2SiO4:Mn thin-film is a kind of nice thin-film which can be used to enhance UV-response of CCD & CMOS detectors..
Optics and Precision Engineering
- Publication Date: Sep. 20, 2021
- Vol. 17, Issue 9, 2106 (2009)
Neutron pulse speciality produced by chop disk
LI Xin-xi, WANG Yan, HUANG Chao-qiang, and CHEN Bo
In order to improve the neutron chopper design,the structural models of a single-chop-disk and an opposite rotate double-chop-disk were established. According to corresponding physical parameters, the neutron pulses formed by the single-chop-disk and the double-chop-disk were simulated by internationally popular McstasIn order to improve the neutron chopper design,the structural models of a single-chop-disk and an opposite rotate double-chop-disk were established. According to corresponding physical parameters, the neutron pulses formed by the single-chop-disk and the double-chop-disk were simulated by internationally popular Mcstas software respectively,and the influence curves of physical parameters on the pulses from the chop-chop- disks were obtained. Then,advantages and disadvantages of the neutron pulses generated by the single-chop-disk and the double disk were discussed. The discussion also refered to the influence of objective physical factors on the errors of neutron pulses generated by the single-chop-disk and the double-chop-disk.Considering the practical application,it suggests that the second cut width of the window in the double-chop-disk should be less than 34 mm in specific physical parameters. The results can provide the reference and theoretical support for optimizing design and manufacturing of choppers..
Optics and Precision Engineering
- Publication Date: Sep. 20, 2021
- Vol. 17, Issue 9, 2112 (2009)
Hybrid inversion algorithm for laser scattering particle size analyzer and its parameter selection
WANG Yan-min, CHEN Qi-xing, and PAN Zhi-dong
A hybrid algorithm combining the characteristics of a conjugate gradient iteration method,a regularization equation and a Successive Over Relaxation (SOR) technique,namely,two-segment iterative method,is proposed to reverse efficiently the light intensity distribution into the particle size distribution in a laser partA hybrid algorithm combining the characteristics of a conjugate gradient iteration method,a regularization equation and a Successive Over Relaxation (SOR) technique,namely,two-segment iterative method,is proposed to reverse efficiently the light intensity distribution into the particle size distribution in a laser particle sizer. The process of convergence can be speeded up and the smoothness of the solution can be enhanced by taking the conjugate gradient iteration as the pre-iteration of next SOR iteration. The solution obtained from the first step treatment is used as the initial solution for the second step. Then,a regularization method is used to correct to the original problem to obtain a stable regularized equation. Finally,the improved SOR method is taken to resolve the regularized equation.Experimental results show the two-segment method can achieve an accurate and stable final solution to this problem. This method is examined with the national standard particulate samples and the theoretical noisy signal,and the results indicate the method is able to distinguish multi-peak particle size distribution (PSD) and can smooth noisy signals..
Optics and Precision Engineering
- Publication Date: Sep. 20, 2021
- Vol. 17, Issue 9, 2120 (2009)
Temperature control system supplied by pulse-drive current for laser range finder
JIA Fang-xiu, and DING Zhen-liang
The light emitting and light receiving devices in laser range finders are low-power components characterized by temperature sensitivity. When a Pt resistance is set in a circuit for temperature measurements,the self-heating effect of Pt resistance influences the resolution of the temperature control system. In order toThe light emitting and light receiving devices in laser range finders are low-power components characterized by temperature sensitivity. When a Pt resistance is set in a circuit for temperature measurements,the self-heating effect of Pt resistance influences the resolution of the temperature control system. In order to decrease the error caused by the self-heating effect,a new set of circuit is proposed based on a pulse-current drive. The models of pulse-current drive circuit and the equivalent heat loop of self-heating effect are set up. Then,the relationship between pulse width and heat quantity accumulation is given and the measuring error from the self-heating effect is decreased sharply by controlling the pulse width properly. Finally,a high-order orthogonal polynomial method is used to compensate the Pt resistor nonlinearity and the high precision of compensation is proved by comparison tests of the temperature measuring module and the absolute standard Pt resistance thermometer. The experimental results show the absolute value of maximum error is less than 0.000 6 ℃ at different temperatures and the stability of temperatures in 0~15 ℃ is better than 0.005 ℃.These results meet the needs of high-accuracy laser range finders..
Optics and Precision Engineering
- Publication Date: Sep. 20, 2021
- Vol. 17, Issue 9, 2128 (2009)
Design and implementation of digital simulation system for detecting image of orbiting optical camera
CHENG Jun, ZHANG Wei, BAO Wen-zhuo, CAO Yi-ming, and CONG Ming-yu
The detecting image simulation for an orbiting camera has played an important role in the feasibility argumentation,the research of information processing method and the test of orbiting optical camera on the ground. In this paper,a relative kinematics model,a catoptric character model,an imaging model of camera,and anThe detecting image simulation for an orbiting camera has played an important role in the feasibility argumentation,the research of information processing method and the test of orbiting optical camera on the ground. In this paper,a relative kinematics model,a catoptric character model,an imaging model of camera,and an imaging model of background stars are established and the digital simulation system for detecting images of an orbital optical camera is designed and realized on the basis of the measurement principle and work environments of space-based optical cameras. Measurement noises and detecting sensitivity are analyzed and the effect of all kinds of disturbing factors on the images are taken into accounts in the simulation modeling. The equivalent calculation from the visible magnitudes of background stars to instrument magnitudes is conducted through the detecting wave band of the camera to improve the fidelity of simulated images (detecting magnitude>9 mV,calculating error<10%). Finally,the simulation software is implemented by means of Visual C++ and OpenGL on the basis of designing simulation flows. The simulation and validation of detecting images is undertaken according to the CCD and optic system parameters of the orbiting optical camera. The conclusion can be drawn that this system provides technical supports for the scheme design and performance test of the camera..
Optics and Precision Engineering
- Publication Date: Sep. 20, 2021
- Vol. 17, Issue 9, 2136 (2009)
Design for thermal control system of electronic equipment in space camera
CHEN Li-heng, WU Qing-wen, LUO Zhi-tao, DONG Ji-hong, and JIANG Fan
The thermal control system of electronic equipment of a space camera was designed and simulated for resolving the problem of its heat dissipation. The thermal design of electronic components,Printed Circuit Boards (PCBs) and their chassis were researched with the approaches of conduction and radiation. Then,a simplifieThe thermal control system of electronic equipment of a space camera was designed and simulated for resolving the problem of its heat dissipation. The thermal design of electronic components,Printed Circuit Boards (PCBs) and their chassis were researched with the approaches of conduction and radiation. Then,a simplified heat dissipation model was established and the effect of heat dissipation was calculated by taking an electronic component as an example. According to the space environment,structure characteristics and the thermal control method of the electronic equipment,a thermal analysis model was built up by TMG software to simulate the thermal control system and to calculate the die temperatures of the electronic components. The results show that the range of temperature of PCBs is from 35.6 ℃ to 45.0 ℃, the range of temperature of electronic components are from 45.4 ℃ to 88.5 ℃,and all of them are lower than the standard heat control temperature indexes.These data show that the proposed thermal design scheme of the electronic equipment of space camera is feasible and reasonable..
Optics and Precision Engineering
- Publication Date: Sep. 20, 2021
- Vol. 17, Issue 9, 2145 (2009)
Optimal control for soft landing of lunar probe
SHAN Yong-zheng, DUAN Guang-ren, and L Shi-liang
In order to decrease the fuel consumption under a finite thrust,a method applying nonlinear programming is presented to solve the optimal control problem on the soft landing of a lunar probe. Based on Pontryagin maximum principle,the lunar soft landing problem is transformed into a two-point boundary value problem in mIn order to decrease the fuel consumption under a finite thrust,a method applying nonlinear programming is presented to solve the optimal control problem on the soft landing of a lunar probe. Based on Pontryagin maximum principle,the lunar soft landing problem is transformed into a two-point boundary value problem in mathematics.In consideration of the bound condition and transversality condition,the resulted two-point boundary value problem is converted into a parameter optimization problem aiming at the initial values of conjugate variables and the terminal time,then it is solved by the nonlinear programming. To reduce the sensitivity of conjugate initial values,the initial values of control variables are used to replace the initial values of conjugate variables based on the transformation between conjugation variables and control variables. The simulated result demonstrates that the proposed method leads to a successful implementation of the lunar soft landing and reduces by 2.1% fuel consumption as compared with that of the traditional method,which shows that the proposed design scheme is simple and effective..
Optics and Precision Engineering
- Publication Date: Sep. 20, 2021
- Vol. 17, Issue 9, 2153 (2009)
Data process of spectroscopic surface plasmon resonance analyzer based on noise analysis
HAO Peng, and WU Yi-hui
To obtain a higher resolution and a widen dynamic range,the relationship between the system resolution and its noise of a spectroscopic Surface Plasmon Resonance(SPR) analyzer was analyzed. For the purpose of improving the Signal to the Noise Ratio(SNR) of the analyzer,the data processing was optimized. The optimizatioTo obtain a higher resolution and a widen dynamic range,the relationship between the system resolution and its noise of a spectroscopic Surface Plasmon Resonance(SPR) analyzer was analyzed. For the purpose of improving the Signal to the Noise Ratio(SNR) of the analyzer,the data processing was optimized. The optimization result indicates that the optimized SPR curve should be between the Reflectance R1 corresponding to the strongest SPR signal and the Reflectance R2 corresponding to the largest SNR. And then,a partial centroid method for data analysis was presented. The experimental results indicate that the dynamical range of measurement has been doubled by the proposed method.As the wavelength resolution of spectrometer has improved by 4 times,the resolution SPR analytical instrument can be increased by 10 times. Finally,the method was used to measure the solutions of Glycerin with refractive indexes between 1.332 5 and 1.360 0,and obtained correlation coefficients are larger than 0.99,which means this method has not any unfavorable influence on the linearity result..
Optics and Precision Engineering
- Publication Date: Sep. 20, 2021
- Vol. 17, Issue 9, 2159 (2009)
Instantaneous three-dimensional profile measurement of tail fin of carp
JIANG Ming, ZHANG Shu, and HE Xiao-yuan
The important role of tail fin of a fish in swimming is to produce a thrust. In this paper,a three-dimensional test and analysis method for instantaneous 3D tail fin profile measurements based on the Fourier transform profilometry was proposed to understand the function of the tail fin. By taking a carp in cruising forThe important role of tail fin of a fish in swimming is to produce a thrust. In this paper,a three-dimensional test and analysis method for instantaneous 3D tail fin profile measurements based on the Fourier transform profilometry was proposed to understand the function of the tail fin. By taking a carp in cruising for an example,the moiré fringes were projected onto a carp tail fin to produce the deformed fringe patterns containing 3D information. Then,a high-speed camera was used to capture these time-sequence images. After Fourier transform,filtering,inverse Fourier transform and unwrap for these phase maps in a 3D phase space,a instantaneous 3D profile model was established and the complex tail fin movements were really reconstructed. Through the analysis of displacement-time curve,the tail-beat frequency is calculated to be 1.42 Hz. It is concluded that the presented study provides a new method both in study of the kinetic characteristic and in quantified analysis of change processing for the tail fin during steady swimming..
Optics and Precision Engineering
- Publication Date: Sep. 20, 2021
- Vol. 17, Issue 9, 2165 (2009)
Silicon microchannel heat sinks for high-power laser diode arrays
YANG Tao, HE Ye, and LIU Ting-ting
To improve the heat dissipation efficiency and to enhance the lifetime and wavelength stability for diode lasers, a roof-like silicon microchannel heat sink characterized by a high integration level is developed. Taguchi robust design method is applied to the design of microchannel heat sinks and orthogonal experimentsTo improve the heat dissipation efficiency and to enhance the lifetime and wavelength stability for diode lasers, a roof-like silicon microchannel heat sink characterized by a high integration level is developed. Taguchi robust design method is applied to the design of microchannel heat sinks and orthogonal experiments and signal-noise ratio calculation are carried out to optimize the key parameters. A microchannel heat sink prototype with a channel width around 50 μm and a roughness better than 0.1 μm is fabricated on a (110) silicon substrate by using a KOH anisotropic etching and an anodic bonding,and laser diode bars are welded on it to test its thermal resistance. The active region temperature rise of the middle bar is estimated by using the temperature coefficient of GaAs laser wavelength,and the thermal resistance is calculated. Experimental results show that the thermal resistance per unit area is 0.070 cm2·K/W,which agrees with that calculated by the finite element method..
Optics and Precision Engineering
- Publication Date: Sep. 20, 2021
- Vol. 17, Issue 9, 2170 (2009)
Numerical analysis and experiment of current-fluid coupling in micro-electroforming
SHAO Li-geng, DU Li-qun, LIU Chong, and WANG Li-ding
The cathode current density and the fluid field relevant to the growth of electroforming layer is studied with numerical analysis to explore the inherent laws of micro-electroforming that is a key technology of UV-LIGA. By taking the crossing electroforming layer of a micro-fluidic chip mold as a research object,a mathThe cathode current density and the fluid field relevant to the growth of electroforming layer is studied with numerical analysis to explore the inherent laws of micro-electroforming that is a key technology of UV-LIGA. By taking the crossing electroforming layer of a micro-fluidic chip mold as a research object,a mathematical model is established. Then,the current density and the fluid field are described with partial differential equations,and the 3D numerical simulation of the micro-electroforming system is performed with the finite element method to obtain the simulated results of the current density distribution and fluid field distribution. Choosing measuring points on the crossing electroforming layer,the simulated growth height during 4 hour electroforming is calculated based on the simulated data of current density and fluid velocities at the measuring points. Finally,the simulated growth height of electroforming layer is compared with that gotten from the micro-electroforming experiment under the same technological condition. The results indicate that the simulated one of electroforming layer is close to the experimental growth height to every measuring point and show low absolute deviations in a maximum of 4.437 μm and a minimum of 0.264 μm. These results also indicate that the numerical simulation can be used in the analysis and design of micro-electroforming,and can reduce the developing time of micro-electroforming technology..
Optics and Precision Engineering
- Publication Date: Sep. 20, 2021
- Vol. 17, Issue 9, 2184 (2009)
Application of control system based on acceleration to disturbance compensation
LIU Jing-hong, ZHU Zhi-qiang, SHEN Hong-hai, HAN Song-wei, and SONG Yu-long
A new control method of disturbance compensation based on acceleration signals is proposed to enhance the servo function of speed control system of a DC torque motor in a precise photoelectric stabilized-platform and to make the system have better dynamical functions and stronger abilities of disturbance rejection. In A new control method of disturbance compensation based on acceleration signals is proposed to enhance the servo function of speed control system of a DC torque motor in a precise photoelectric stabilized-platform and to make the system have better dynamical functions and stronger abilities of disturbance rejection. In this method,a nominal controller is established and a disturbance observer is created using acceleration signals to compensate quickly and precisely the external disturbance and to reduce the effect of the model error. Thus,the dynamical function and disturbance rejection ability of the system are enhanced. The experiment result shows that this control method can improve the dynamic performance of the motor control system,which accelarates motor responds and restrains overshoots.For the step external disturbance,the system speed only shows a pulse fluctuation with a width of 0.1 s,and the amplitude is one half of that of PID controller. Besides,the control system is robust towards the uncertainty of the motor model. These results show that the method has magnificent effects and good applications and is very suitable for engineering..
Optics and Precision Engineering
- Publication Date: Sep. 20, 2021
- Vol. 17, Issue 9, 2191 (2009)
Structure design of precise displacement platform without guiding apparatus
GAO Yun-guo, ZHANG Qian, SHI Ya-li, JIANG Wei-wei, and PENG Yan
A new low-cost precise displacement platform without a guiding apparatus was developed to perfect its working performance and to improve the displacement straightness and position accuracy of the system. Based on the theories of parallelogram and proportional lever,the structure of the platform was designed and the worA new low-cost precise displacement platform without a guiding apparatus was developed to perfect its working performance and to improve the displacement straightness and position accuracy of the system. Based on the theories of parallelogram and proportional lever,the structure of the platform was designed and the work principle was introduced. Then,the movement parts in the platform were analyzed by the Finite Element Method(FEM). Finally,an autocollimator and a high precise measuring head were used in the measurement of the displacement straighness and the the error of the lifting displacement,respectively. The experiment results show that the error of the displacement straighness is smaller than 1" and the error of the lifting displacement is less than 0.02 mm,which shows that the structure achieves the design desire completely. The platform in applications is proved that it is easy to install and maintain and can be used in a weightless condition,so it is suitable for the spaceflight fields and other precise displacement systems..
Optics and Precision Engineering
- Publication Date: Sep. 20, 2021
- Vol. 17, Issue 9, 2199 (2009)
Deformation design of long-spherical hollow rotor of electrostatic suspended gyroscope
SUN Xin-min, and TAO Li-zhi
For improving the dynamic roundness of the sphere hollow rotor in an electrostatic gyro,a rotor was designed to be a long sphere with long-polarized and short-equatorial diameters in a static state to compensate the roundness error caused by the centrifugal load. According to the load elastic distortion formula from thFor improving the dynamic roundness of the sphere hollow rotor in an electrostatic gyro,a rotor was designed to be a long sphere with long-polarized and short-equatorial diameters in a static state to compensate the roundness error caused by the centrifugal load. According to the load elastic distortion formula from the elasticity shell theory,the superposition formula of surface distortions produced by the radial load and the centrifugal load for hollow Be rotor in the Electrostatic Suspended Gyroscope(ESG) was established by using the small distortion independent action and synthesis theory. Then,a long spherical hollow Be rotor with long-polarized and short-equatorial diameters was constructed by the superposition formula. Finally, a sample was taken to explain the design,processing and survey of the long spherical hollow rotor. Experimental results indicate that the polar radius of the long spherical hollow Be rotor is 0.52 μm longer than equator radius,which is well coincident with the design value of 0.54 μm..
Optics and Precision Engineering
- Publication Date: Sep. 20, 2021
- Vol. 17, Issue 9, 2206 (2009)
Measurement and nonlinear correction for micro-displacement of piezoceramic tube
DONG Wei-jie, SONG Zhi-yang, and CUI Yan
A simple way to measure and correct the micro-displacement of a piezoceramic tube used in an Atom Force Microscope(AFM) is proposed. The X/Y micro-displacement is detected by an eddy current meter and it is amplified by 100 times to improve the detection sensitivity. The relationships between the displacements of piezoA simple way to measure and correct the micro-displacement of a piezoceramic tube used in an Atom Force Microscope(AFM) is proposed. The X/Y micro-displacement is detected by an eddy current meter and it is amplified by 100 times to improve the detection sensitivity. The relationships between the displacements of piezocaramic tube and the control voltages are obtained,and the highest resolution of displacement is calculated to be 0.4 nm. According to the working feature of the tube,the nonlinear correction is realized by applying non-equidistant control voltage sequences to scanning equidistant pixel,in which non-equidistant control voltage sequences with different pixel resolutions are obtained through interpolation based on the measured displacement-voltage relationship. The experimental results show that the maximum hysteresis error of full scale is reduced from 10.1% to 0.4%. It is concluded that the proposed method can adjust the scan frequency and pixel resolution easily,and can reduce the complexity of correction algorithm greatly..
Optics and Precision Engineering
- Publication Date: Sep. 20, 2021
- Vol. 17, Issue 9, 2212 (2009)
Design of biochemical sensor based on high-Field Asymmetric Ion Mobility Spectrometry
LI Hua, WANG Xiao-hao, TANG Fei, and LIN Zhen-xiang
A novel biochemcal sensor based on a high-Field Asymmetric Ion Mobility Spectrometry(FAIMS) theory is fabricated and characterized,which is mainly composed of an ionization source,a drift tube and a detector. By taking a VUV lamp as the ionization source and choosing an acetone with nitrogen (99.999%) as the carrier gaA novel biochemcal sensor based on a high-Field Asymmetric Ion Mobility Spectrometry(FAIMS) theory is fabricated and characterized,which is mainly composed of an ionization source,a drift tube and a detector. By taking a VUV lamp as the ionization source and choosing an acetone with nitrogen (99.999%) as the carrier gas,the biochemical sensor works at ambient pressure.Moreover,two kinds of drift tubes consisting of two parallel plate electrodes are fabricated. One drift tube with the dimension of 25 mm×10 mm×1 mm is composed of two copper planar electrodes, the other with the dimension of 20 mm×10 mm×1.5 mm is fabricated by Micro Electro-Mechanical System(MEMS ) technology. For the former,the gap between the two drift tubes is 1 mm and the electrical field is above 10 000 V/cm;but for the latter,the gap between MEMS drift tube is 1.5 mm and the electrical field is less than 10 000 V/cm,which can not separate the acctone. With a peak-peak of rectangular asymmetric waveform voltage up to 1 600 V,a frequency of 195.8 kHz,a duty cycle of 30% and a compenstaion voltage of -8.63 V,the acetone displacement is compensated and the sensor ability to separate ions is demonstrated by an experiment using the planar copper drift tube..
Optics and Precision Engineering
- Publication Date: Sep. 20, 2021
- Vol. 17, Issue 9, 2218 (2009)
Optimization design of scroll and pitch and their control errors on aerocraft
YAN De-jie, HAN Cheng-shan, and LI Wei-xiong
In order to reduce the influence of scroll and pitch movements on the image quality of a TDICCD space camera,the requirements for the scopes of scroll angle and pitch angle and their control errors are put forward to obtain an image with high signal noise ratios and high resolution. According to the mechanism of cameraIn order to reduce the influence of scroll and pitch movements on the image quality of a TDICCD space camera,the requirements for the scopes of scroll angle and pitch angle and their control errors are put forward to obtain an image with high signal noise ratios and high resolution. According to the mechanism of camera image motion,the image motion caused by the scroll and pitch of aerocraft and the formula for calculating the image motion are given. The image quality is evaluated by the Modulation Transform Function(MTF),and the scopes of scroll angle and pitch angle that can meet the requirements of the space camera image quality are determined. Furthermore,the influence of the scroll angle and pitch angle on the ground pixel resolution is analyzed. From calculations,it is concluded that,when the control error of scroll angle and pitch angle is 0.1° during the imaging and the angle of axis of sight caused by the scroll angle and pitch angle is no more than 4.8°;or the control error of scroll angle and pitch angle is 0.05° and the angle of axis of sight is no more than 9.5°,the requirements of the integration progression is 96 and the MTF is no less than 0.95 can be met. The experimental results indicate that the proposed method is simple and easy to implement,which is suitable for the research on image quality of the TDICCD space camera..
Optics and Precision Engineering
- Publication Date: Sep. 20, 2021
- Vol. 17, Issue 9, 2224 (2009)
Increasing update rate for star sensor by pipelining parallel processing method
ZHONG Hong-jun, YANG Meng-fei, and LU Xin
The update rate is a key characteristic of star sensors,and it has been considered as an important research direction in future.In this paper,a method for increasing the update rate of a star sensor is presented and the composition of update time is introduced.The parallel processing mechanisms by using a pipelining meThe update rate is a key characteristic of star sensors,and it has been considered as an important research direction in future.In this paper,a method for increasing the update rate of a star sensor is presented and the composition of update time is introduced.The parallel processing mechanisms by using a pipelining method are analyzed emphatically,then a sequential working mode,a two cycle pipelining mode,a three-cycle pipelining mode and a more cycle pipelining mode are successfully realized on the engineering prototype. Moreover,the sequence diagrams and formulas of update rate for different modes are given,and the specific software and hardware implementation methods are described. Finally,a software interpolation method for increasing update rate of the star sensor is introduced.The experimental results indicate that the update rate by parallel processing mechanisms using the pipelining method can reach 8-10 Hz,which has increased by 2-3 times as compared with that of the traditional method..
Optics and Precision Engineering
- Publication Date: Sep. 20, 2021
- Vol. 17, Issue 9, 2230 (2009)
Particle swarm optimizer tracking based on DSP parallel system
XU Ting-fa, ZHAO Si-hong, ZHOU Sheng-bing, and NI Guo-qiang
For the problem of a large amount and slow speed in the serial Particle Swarm Optimization(PSO) algorithm,a parallel PSO tracking algorithm based on Digital Signal Processing(DSP) parallel system is proposed. In the development of the four DSP parallel systems,a parallel PSO tracking algorithm is designed using the mesFor the problem of a large amount and slow speed in the serial Particle Swarm Optimization(PSO) algorithm,a parallel PSO tracking algorithm based on Digital Signal Processing(DSP) parallel system is proposed. In the development of the four DSP parallel systems,a parallel PSO tracking algorithm is designed using the message passing model and the Master-Slave mode of a single species. The initial setting is realized by DSP-A,while DSP-B,DSP-C and DSP-D are used to calculate the fitness of each particle in parallel. Finally,the fitness of each particle and the pros and cons of individual extreme are compared by DSP-A,and then a better individual extreme and an optimal solution of the entire population are chosen to update the position and velocity of each particle. Comparing with the serial PSO algorithm,the speedup ratio and efficiency of the simulation algorithm based on the actual sequence of image are 2.525 and 63.13%,respectively. The method supplies a new option to implement a large-scale global optimization target tracking project..
Optics and Precision Engineering
- Publication Date: Sep. 20, 2021
- Vol. 17, Issue 9, 2236 (2009)
Design and implementation of hyper-speed FFT processor
FAN Jin, JIN Sheng-zhen, and SUN Cai-hong
Design of a high-speed Fast Fourier Transform(FFT) processor is one of key points in a real time signal processing system.In this paper,a high speed and a hybrid architecture FFT processor combining a parallel processing with a Single-Path Delay Feedback(SDF) pipeline is designed based on Field Programmable Gate Array(Design of a high-speed Fast Fourier Transform(FFT) processor is one of key points in a real time signal processing system.In this paper,a high speed and a hybrid architecture FFT processor combining a parallel processing with a Single-Path Delay Feedback(SDF) pipeline is designed based on Field Programmable Gate Array(FPGA) chip. Compared with the full parallel architecture,the memory cost of the designed processor decreases,thus the speed is higher than that of the SDF pipeline architecture. An algorithm and a design model for the processor are established and the three modules in the processor are optimized to decrease the resource cost greatly,thus the speed is higher than that of generous pipeline architectures.a verification is carried out with the FPGA simulations and hardware circuits’ platform in a lab,the results show that the operating frequency reaches 150 MHz and the data flow exceeds 600 Msps..
Optics and Precision Engineering
- Publication Date: Sep. 20, 2021
- Vol. 17, Issue 9, 2241 (2009)
Analysis and design of robust self-tuning IMC for opto-electronic tracking system
JI Wei, LI Qi, XU Bo, and ZHAO De-an
In consideration of the measurement time-delay and plant model uncertainty from signal processing and transmissiances in an imaging tracker,a robust Internal Model Control (IMC) strategy is designed for the opto-electronic tracking system. Firstly,the equations for designing the IMC controller based on the gain and phaIn consideration of the measurement time-delay and plant model uncertainty from signal processing and transmissiances in an imaging tracker,a robust Internal Model Control (IMC) strategy is designed for the opto-electronic tracking system. Firstly,the equations for designing the IMC controller based on the gain and phase margin specifications are given in detail. Then,the robust stability condition and the design criterion of parameters under plant/model mismatch are derived. Finally,a optimization method based on a quadratic cost function is introduced to adjust controller's parameters adaptively for improving the controlling ability and robust performance for the system. The experimental results in a four-axis opto-electronic tracking servo turntable indicate that the tracking precision is less than 1 mil,which is effective to overcome tracking errors caused by measurement time-delay and to ensure fast tracking for targets..
Optics and Precision Engineering
- Publication Date: Sep. 20, 2021
- Vol. 17, Issue 9, 2247 (2009)
Application of wavelet filtering and singularity analysis to evaluation of surface roughness
CUI Chang-cai, ZHANG Geng-pei, ZHANG Bin, and ZHANG Qian
In order to locate and exclude the singularity induced by vibration and to evaluate the surface texture exactly,a wavelet singularity detection and filtering method is presented. Firstly,the wavelet singularity analysis is used to preprocess the sampled surface and then the 3-dimensional roughness profile is extracted In order to locate and exclude the singularity induced by vibration and to evaluate the surface texture exactly,a wavelet singularity detection and filtering method is presented. Firstly,the wavelet singularity analysis is used to preprocess the sampled surface and then the 3-dimensional roughness profile is extracted by using the wavelet filter. Then, the typical evaluation parameters of roughness profile are computed and the results are compared with two kinds of samples: measured data manually added singularity and measured data with singularity originally. Experimental results show that for the first kind of data roughness parameters after singularity processing for the first kind of data with added singularity are similar to those of original surface,and the relative changes of Sa,Sz,Sq,Ssk and Sku are 0.27%、0.78%、0.51%、0.04%、1.04% respectively. The relative changes of Sa,Sz,Sq,Ssk and Sku before and after singularity processing for the first kind of data with added singularity are 1.14%、20.63%、1.95%、3.81%、8.86%. For the second kind of data the relative changes of Sa,Sz,Sq,Ssk and Sku before and after singularity processing are 6.2％、27.47％、9.54％、131.62％、53.77％respectively. The experiments prove that more reasonable evaluation results can be obtained if the singularity is excluded from the surface before the roughness profile is extracted by using the wavelet filtering..
Optics and Precision Engineering
- Publication Date: Sep. 20, 2021
- Vol. 17, Issue 9, 2255 (2009)
Low complexity image compression scheme for hardware implementation
XU Yong, XU Zhi-yong, ZHANG Qi-heng, and ZHAO Ru-jin
Because ordinary image compression algorithms and other compression methods based on Digital Signal Processors(DSPs) or PC machines can not satisfy the demands of high speed and small volume image compression applications,a low complexity image compression scheme based on the 5/3 Discrete Wavelet Transform (DWT) is proBecause ordinary image compression algorithms and other compression methods based on Digital Signal Processors(DSPs) or PC machines can not satisfy the demands of high speed and small volume image compression applications,a low complexity image compression scheme based on the 5/3 Discrete Wavelet Transform (DWT) is proposed in this paper.Firstly, the correlation redudancy of image is excluded with 3-level z-dimension DWT. Secondly, the DWT coefficients are quantized according to the conversion gain of wavelet subband and the predict of LL subband is quantized. Finally,the image compression by combining adaptive zero run-length coding with Exp-Golomb coding is realized based on the probability distribution. Experimental results show the scheme has advantages in low computational complexity and hardware implementation,while it maintains relatively high performance in compressing various images.Moreover,it offers a high speed image compression of 175 Mpixel/s by FPGA,which provides an algorithm base for developing high speed image compression devices..
Optics and Precision Engineering
- Publication Date: Sep. 20, 2021
- Vol. 17, Issue 9, 2262 (2009)
Computed tomography image edge degradation model and its application to image size measurement
CHEN Ping, PAN Jin-Xiao, and LIU Bin
In consideration of the requirements of quality inspection and reverse design for Computed Tomography(CT) products,a CT image edge degradation model was established and used in the image size measurement to improve the measurement accuracy. At first,the model was established based on mathematical description of CT imagIn consideration of the requirements of quality inspection and reverse design for Computed Tomography(CT) products,a CT image edge degradation model was established and used in the image size measurement to improve the measurement accuracy. At first,the model was established based on mathematical description of CT image edge degradation. Then,the parameters of degradation model were confirmed according to the image intensity and inflexions of CT image gray curves. Finally,this constructed degradation model was used to restore the primary CT image edge and accurately extract the information of image edge. Hence,the measurement of CT image is accomplished. Experimental results indicate that the relative error is 2% for the CT image with a poor step edge,which has decreased by 1.5% as compared with those of traditional image measurement methods. These results show that this new model can effectively extract the information of CT image edge,and can get an accurate measurement result..
Optics and Precision Engineering
- Publication Date: Sep. 20, 2021
- Vol. 17, Issue 9, 2269 (2009)
Image feature extraction and matching technology
YANG Xiao-min, WU Wei, QING Lin-bo, HUA Hua, and HE Xiao-hai
With the aim to improve the stability and reliability of image matching,the Scale Invariant Feature Transform algorithm(SIFT) is applied to image feature extraction and image matching. The SIFT can find out those feature vectors in different scale spaces and can extract image features and image description with the invWith the aim to improve the stability and reliability of image matching,the Scale Invariant Feature Transform algorithm(SIFT) is applied to image feature extraction and image matching. The SIFT can find out those feature vectors in different scale spaces and can extract image features and image description with the invariantce for scale changes and rotations and the flexibility for illumination variation and affine transformation. In this paper,the SIFT method is used to get the special point of an image and its features. Then, the features are matched with the criterion of the nearest neighbor based on confidence. Finally,the features in the image with different illumination conditions,focus lengths and shooting angles are extrated and matched.The experimental results prove that the features extracted by SIFT method have excellent adaptive and accurate characteristics for the illumination,transfer and the rotation transform and have match accuracy more than 90%,which are useful for the fields of image recognition and image reconstruction..
Optics and Precision Engineering
- Publication Date: Sep. 20, 2021
- Vol. 17, Issue 9, 2276 (2009)
Inspection of surface mounted IC devices with edge and color features
WU Hui-hui, ZHANG Xian-min, and HONG Shi-liang
In order to satisfy the on-line inspection requirements of the surface mounted Integrated Circuit(IC) devices on Printed Circuit Boards (PCB),an inspection algorithm based on the edge integral projection and color statistical features was presented. The features of the IC devices with different mounted qualities under In order to satisfy the on-line inspection requirements of the surface mounted Integrated Circuit(IC) devices on Printed Circuit Boards (PCB),an inspection algorithm based on the edge integral projection and color statistical features was presented. The features of the IC devices with different mounted qualities under a three-color (red,greed,blue) structure light source were analyzed. Then,the horizontal and vertical edges were extracted with the Sobel arithmetic operator and the edges were projected for avoiding the difficulty of right thresholding. Based on the integral projections of the edges,the horizontal and vertical borders of the IC leads were obtained by the maximum neighbor gradient algorithm and the sliding location window algorithm,respectively. After location the leads,the defects such as missing devices,wrong devices,shifts and skews were inspected. Finally,the statistical color features in HSI (hue,saturation,intensity) space were extracted to detect the defects of lift leads and wrong polarity. Experiment results show that the proposed method can identify the defects of the IC devices effectively,the total success rate is 97.9% and the time consuming for single IC device is about 30 ms. It has verified the validity of this algorithm in terms of the recognition rate and speed..
Optics and Precision Engineering
- Publication Date: Sep. 20, 2021
- Vol. 17, Issue 9, 2283 (2009)
Partially overlapped sub-block histogram equalization based on recursive equal area separateness
SUN Chun-feng, and YUAN Feng
The traditional histogram equalization is unable to preserve the input image brightness,when the contrast of an image is enhanced. Based on a Partially Overlapped Sub-block Histogram Equalization algorithm (POSHE),the recursive separateness method is used in the process of sub-block histogram equalization. A brightnessThe traditional histogram equalization is unable to preserve the input image brightness,when the contrast of an image is enhanced. Based on a Partially Overlapped Sub-block Histogram Equalization algorithm (POSHE),the recursive separateness method is used in the process of sub-block histogram equalization. A brightness preservation partially overlapped local histogram equalization algorithm which can preserve the brightness is proposed. The sub-block image is separated recursively into different sub-images with the cumulative density function (CDF). Then,each sub-image histogram is equalized within its respective gray range,and all the sub-images are incorporated into the equalized sub-blocks. Both linear and bilinear interpolations are used in the equalized sub-block based on a step size to avoide the generation of blocking effects and the influence on image details. Experimental results show that the average Peak Signal Noise Ratio(PSNR) is improved by 0.063~6.633 dB compared with those of traditional interpolation methods. In fact,the local image details are enhanced,and the input image brightness is also preserved effectively. For the influence of the blocking effects on the image is eliminated,the equalized image shows a more natural visual impression..
Optics and Precision Engineering
- Publication Date: Sep. 20, 2021
- Vol. 17, Issue 9, 2292 (2009)
Fast color transfer method for image fusion
LI Guang-xin, and XU Shu-yan
With linear YCBCR space and Reinhard’s statistical color transfer strategy,a color transfer method for image fusion,named YCBCR color transfer method,is proposed to produce a fused image with a natural daytime color appearance. This approach has low computational complexity,and is very suitable for color image fusion. With linear YCBCR space and Reinhard’s statistical color transfer strategy,a color transfer method for image fusion,named YCBCR color transfer method,is proposed to produce a fused image with a natural daytime color appearance. This approach has low computational complexity,and is very suitable for color image fusion. Furthermore,it facilitates enhancing the luminance contrast of the color fused image by replacing the luminance component of the color fused image with the high-contrast grayscale fused image. This paper mathematically proves that color spaces conforming to the general YCBCR space framework,such as YUV space,can be used as an alternative to YCBCR space in color transfer. Experimental results demonstrate that the YCBCR color transfer method is able to give color fused image a natural daytime color appearance,and has better capability of recoloring color fused image than the Reinhard’s approach..
Optics and Precision Engineering
- Publication Date: Sep. 20, 2021
- Vol. 17, Issue 9, 2301 (2009)
Approach to dim and small target detection based on fuzzy classification
LI Xin, ZHAO Yi-gong, CHEN Bing, and XUE Jing
In order to achieve robust dim and small target detection in a infrared cloud clutter,a new approach based on fuzzy classification is proposed. Different kinds of class regions are extracted from the query image to get several classification models to describe different classifications in the image exactly.The classifiIn order to achieve robust dim and small target detection in a infrared cloud clutter,a new approach based on fuzzy classification is proposed. Different kinds of class regions are extracted from the query image to get several classification models to describe different classifications in the image exactly.The classification based on such models will classify the image effectively and achieve robust dim and small target detection. Firstly,the dim and small infrared target image are analyzed and eleven kinds of class regions are proposed to describe the sky,cloud and the target in the image. Then,class feature vectors and class kernels are defined,and the class kernels of eleven class regions are extracted from the query image. Finally,the class similar coefficient and class similarity degree are defined according to the fuzzy classification theory. The target detection is achieved by reserving a dim and small target class,after image classification and class merge are performed. Experimental results show that the proposed method can classifly different kinds of regions in the dim and small infrared target image with a Signal Noise Ratio(SNR) larger than 1.0 exactly and can realize the robust dim and small infrared target detection in heavy background clutter..
Optics and Precision Engineering
- Publication Date: Sep. 20, 2021
- Vol. 17, Issue 9, 2311 (2009)
Adaptive multi-spectrum object tracking of multi-feature fusion based on Rao-Blackwellized particle filter
LI Chun-xin, and WANG Xiao-tong
Aiming at the problem of real time and reliability of visual object tracking in a clutter background,an adaptive tracking algorithm by fusion of the color rectangle feature with the Edge Orientation Histogram is presented based on the Rao-Blackwellized Particle Filter(RBPF). To improve the tracking speed and precision,Aiming at the problem of real time and reliability of visual object tracking in a clutter background,an adaptive tracking algorithm by fusion of the color rectangle feature with the Edge Orientation Histogram is presented based on the Rao-Blackwellized Particle Filter(RBPF). To improve the tracking speed and precision, the RBPF is adopted to improve the filter performance,and an integral image is used to quickly compute the color rectangle feature and Edge Orientation Histogram.Finally,a fuzzy logic is applied to adaptively adjust each feature weight and to improve tracking accuracy in real time. The simulation result from a video tracking illustrates that the algorithm is robust and effective for visible and infrared object tracking under complex backgrounds..
Optics and Precision Engineering
- Publication Date: Sep. 20, 2021
- Vol. 17, Issue 9, 2321 (2009)
Discontinuity preserving stereo matching using variable window
LU A-li, and TANG Zhen-min
For solving the mismatching problem in computer vision,a discontinuity preserving stereo matching algorithm using variable windows in an energy minimization framework was proposed. Firstly,a dissimilarity combing intensity and gradient information was introduced.Then,according to the cost function composed of the averaFor solving the mismatching problem in computer vision,a discontinuity preserving stereo matching algorithm using variable windows in an energy minimization framework was proposed. Firstly,a dissimilarity combing intensity and gradient information was introduced.Then,according to the cost function composed of the average measurement error, error variances and the error biases of larger windows,the best window for each disparity was chosen as the matching cue,and a scanline optimization method was used to search optimum paths under the constraint of depth discontinuity. Finally,a dense disparity map was obtained by tracing optimum paths. Experimental results show that the proposed algorithm can not only process the low texture areas and depth discontinuities,but also enforce the consistency between the two neighbors. Moreover,the computation cost has almost decreased by three-fourths as compared with that of the original algorithm..
Optics and Precision Engineering
- Publication Date: Sep. 20, 2021
- Vol. 17, Issue 9, 2328 (2009)
Real-time detection of airport runway by extracting line feature
DI Nan, ZHU Ming, and WANG Yi-nan
A novel method combing an Improved Chain Code Based Edge Tracking (ICCBET) with Pyramid Hough Transform (PHT) is proposed to detect the airport runway in real time successfully ,for the traditional line detection method by using chain code based edge tracking and Hough transform is sensitive to the noise and hard to saA novel method combing an Improved Chain Code Based Edge Tracking (ICCBET) with Pyramid Hough Transform (PHT) is proposed to detect the airport runway in real time successfully ,for the traditional line detection method by using chain code based edge tracking and Hough transform is sensitive to the noise and hard to satisfy the real time applications.The ICCBET is used to remove short and curving lines,reduce pixels,confirm approximate orientation and to shorten the angle range of PHT processes. Then,the computation cost is reduced considerably by using the stage of pyramid HT. Finally,a chain list array for the image is designed to fix the memory to avoid the overflow which arises from building chain list with memory dynamic allocation. The algorithm has been applied in the TMS320C6416 hardware system. The experiments on various images show that the computation cost by proposed method has decreased by 29 times as compared with that of traditional Hough method and it overcomes the blur and occlusion compared with the original chain code based edge tracking for line detection..
Optics and Precision Engineering
- Publication Date: Sep. 20, 2021
- Vol. 17, Issue 9, 2336 (2009)
Track-before-detection for multi weak targets based on Rao-Blackwellized particle filter
LI Cui-yun, and JI Hong-bing
The track-before-detection (TBD) based on a Rao-Blackwellized Particle Filter(RBPF) is proposed for detecting and tracking a number of weak targets in an infrared image with low Signal to Noise Ratio (SNR). A system dynamic model and a measurement model of the infrared image are presented. Then, the state vector is parThe track-before-detection (TBD) based on a Rao-Blackwellized Particle Filter(RBPF) is proposed for detecting and tracking a number of weak targets in an infrared image with low Signal to Noise Ratio (SNR). A system dynamic model and a measurement model of the infrared image are presented. Then, the state vector is partitioned as a linear state variable and a nonlinear state variable with RBPF,which is computed by the Kalman filter and the particle filter,respectively. Finally,the present and absent statistics are defined and the flowchart of the RBPF-TBD for multi weak targets with a constrained condition are given. The simulation results of the infrared image sequences in different SNRs show that the RBPF-TBD can reduce the state’s estimation error and can improve the detection probability. For a single target by TBD,the simulation indicates that the consumed time is 0.0387 s/frame averagely. Under the same particle number,RBPF can get a highter filtering accuracy.For two targets with a SNR of 6 dB in different space positions, the simulation shows that constrained tracking can avoid the inference of present targets. The target presence and absence declaration delays averagely are 2.74 frames and 1.13 frames. These results show that the proposed algorithm for multi weak targets is capable of detecting the target presence and absence,and is capable of tracking the target efficiently..
Optics and Precision Engineering
- Publication Date: Sep. 20, 2021
- Vol. 17, Issue 9, 2342 (2009)
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