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Novel high-resolution vibration sensor based on laser frequency splitting technology
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The prototype of a novel high resolution vibration sensor based on HeNe laser frequency splitting technology is presented in this paper and the results of a series of experiments are reported. A seismic inertial structure has been developed to realize the absolute measurement. The parameters of the inertial structure can be selected to be suitable for different vibration frequency bands and different sensitivities. In the experiments the highest resolution of 15nm on the measurement of vibration amplitudes are obtained. The sensor has a good potential perspective to be applied in the high-resolution and high- sensitivity, low or middle frequency vibration measurements.
Position and attitude measurement of moving target using laser tracking system with multiple measuring stations
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Dynamic geometric parameter measurement plays an important role in most industries. Research and development on this technology have attracted great attention. We proposed a laser tracking system for measuring development of laser tracking technology, a laser tracking system consisting of three tracking and measuring stations is described in detail. The three stations track respectively three retro reflectors on the moving target, and measure the position and attitude. We built the mathematical model of measurement and developed the algorithm for processing data. According to the homogeneous coordinate transformation, we deduced the formulae for computing coordinates and attitude under different coordinate systems. Some key techniques of the measuring system are discussed at the end of the paper.
Measuring particulate concentration by means of scattered light scintillation
Anshi Chen,
Jiming Hao,
Zhongping Zhou,
et al.
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A new method of measuring particulate concentration in flue gas is proposed. In the new method, the fluctuation of scattered light is used for calculating particulate mass concentration. Laboratory experiments show that the method can be applied to analyze the presence of dust particles in the flue gas stream. The benefits from the method are insensitivity to lens contamination and particle color change.
High-precision measurement of the wavelength shift of in-fiber Bragg grating with strain gauge
Fang Xie,
Shulian Zhang,
Yan Li,
et al.
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A new method is presented to interrogate the reflected wavelength shift of in-fiber Bragg grating used as sensors. The system can locate the center of the reflected wavelength of in-fiber Bragg grating with high precision and erase the influence of non- linearity and hysteresis of pzt from the measurement data effectively.
Processing application used in beam characterization
Wei Sun,
Chunqing Gao,
Guang Hui Wei
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CCD based laser beam characterization system is widely used in many experimental and industrial applications. Besides many factors of the CCD measurement system and the properties of the beams power density distributions to be measured, the obtained accuracy of laser beam characterization also strongly depends on the effectiveness of data processing algorithm. In this paper a Windows based processing application and its features and key processing algorithm are introduced and also a software related proposal is raised, such as common interface of measurement on simulated beam with given beam width, background and noise; universal image data storage format which would facilitate the international wide collaboration on the effectiveness evaluation of different processing application and system.
Modal characteristics of quartz tuning-fork angular rate microsensor by means of FEM
Ying Wang,
Yunan Sun,
BingKun Qin,
et al.
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Quartz tuning-fork angular rate sensor (gyroscope) is a new kind of vibratory gyroscope which has a big market. The solid model of the quartz tuning fork is established and finite element method is used in studying its modal characteristics in this paper. The influence of the gyroscope structural dimension on the resonant frequency and structural modes is investigated, which offers reliable basis for the structure design of the micro gyroscope. Software Ansys5.6 is used in this work.
Interferogram processing with wavelet analysis and spectrogram reconstruction
Jianjun Chu,
Yuejuan Jiang,
Quanchen Li,
et al.
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Spatial modulated imaging Fourier-transform spectrometers (SMIFTS) have the advantage of high Etendue (throughput), therefore, compared with the temporal modulated IFTS, the interferogram obtained from SMIFTS have higher Signal-to-Noise Ratio (SNR). Despite of this, noise on the interferogram will also affect the quality of the spectrograms, which were reconstructed from the interferogram by discrete Fourier- transform (DFT). This paper particularly describes the noise and its effect on the spectrogram and presents a novel method to preprocess the interferogram by using of Wavelet analysis. The result between this method and traditional low pass filtering is given as well.
Online measuring system for amorphous strip thickness
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In amorphous strip fabrication, the stripe thickness is of the characteristics of the importance, which is decided by the velocity and flow of melting amorphous squirted from the jet, the distance between the jet and the cooling roller, and the rotating speed of the cooling roller. In this paper, a system is developed for the online measurement of the thickness of the amorphous strip, so that the machine can be adjusted accordingly in time to make sure the product meets its specifications. Considering onsite conditions in the workshop, laser triangle method combined with suitable software and hardware enhancement is proposed. The experimental performance of this measurement system was tested and verified in our laboratory and in a workshop in China.
Digital simulation for low-light-level night vision imaging system
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Construct the transform function model of low-light-level night vision imaging system and its components; Convert the input image with a certain pattern through FT to get the frequency spectrum of it, and filter the frequency spectrum of input image by use of the transform function model. And then, convert the filtered frequency spectrum of input image through IFT to get the filtered image. Thus, implement the digital simulation of low-light-level night vision imaging system by computer.
Image simulation for photoelectric imaging system
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Use the transform function theory to analyze the imaging characteristic of photo electronic imaging system, and set up the simulation system for detecting characteristic of it with the high-speed DSP TMS320C6201. Through the simulation, we can evaluate the detecting characteristic of a certain photo electronic imaging system, change its components while simulating, and then compare the characteristic before change with after change to provide intuitionistic reference for optimizing design of photoelectric imaging system.
Quick and dynamic measurements of geometric errors of CNC machines
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In this paper, a system that is used to measure dynamically all kinds of geometric errors of CNC machines is introduced, and some experiment results are given. The experiment results showed some significant differences between the static and dynamic error characteristics. Through analyses of the dynamic signals in both time and space fields, some error resources of the CNC machines can be found. In addition, any shape of contouring errors can be directly measured by this system without using a ball bar on other devices, which provides a simple and practical way to evaluate contouring errors of CNC machines.
Remote sensing to ocean by using Brillouin scattering: test of sound speed and submerged object
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The laboratory experimental test of sound speed for fresh water and typical salt water (salinity Sequals35%) are reported for different water temperatures. Considering that the returned signal contains both Rayleigh and Brillouin peak (which have Gaussian and Lorentzian line shapes respectively), the measured data are fitted by mixed function of Gaussian and Lorentzian. Then, the sound speed is obtained by Brillouin shift that is determined with FSR of the Fabry-Perot. For the testing of submerged object, it has fewer requirements on the accuracy. The experimental results without and with submerged object are given. All results show that Brillouin scattering is a good method for measuring sound speed in water and for testing of submerged object.
Approach to application of segment and its deformation measurement
Tiejun Li,
Zhiming Liu,
Jianhui Zhang,
et al.
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A digital close photogrammetry approach is presented to application of segment and its deformation measurement, which is accurate and speedy. And it has been tested in application of segment and its deformation measurement in Yellow River Project of China. The practical results show that it is feasible.
Computer simulation of laser drilling in permanent magnetic material
Shengsheng Liu,
Changjiang Li
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Based on the heat conduction theory, the mathematical model of process of drilling in the surface of SMCO5 permanent magnetic rotor by a pulse laser (Nd3+ : YAG) has been gotten. And the heat affected zones are analyzed and discussed. The tendencies of the hole depth and radius changing with various parameters of YAG laser are given. And the quantitative figures of the best combination for different specifications of laser production are put forward.
Three-dimensional welding and cutting using high-power CO2 or YAG laser
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In this paper, the theory of 3D laser welding and cutting was established firstly. Then the expert system for 3D laser processing and software of 3D laser processing CAD/CAM were developed, respectively. Under the guidance of these software, with high power CO2 laser, the 3D covers of a car have been cut and edge smoothed, which decrease the number of models and shorten the period of production. With adoption of this technology, the covers of extended Hong Qi cars and furthermore Da Hong Qi cars have been processed successfully, which will bring out the innovation of production design and the revolution of processing technology in manufacture industry.
Optoelectronic inspection method for IC shell blanks
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This paper propounds an optoelectronic self-study inspection method for IC' shell blanks on the basis of comparison with standardized workpieces. First, the inspection system self- studies. Second, the system automatically inspects the products, and those exceeding the acceptance tolerance will be singled out as the unqualified. By comparing the inspected workpieces with the standard ones the system can identify defects such as shutdown and cutting-out. This method is of high inspection speed, powerful anti-interference ability, and high flexibility in term of shape variety.
Novel image connection method used in the measurement of geometrical parameters
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The measurement of geometrical parameters using image measurement technology is used widely in the industrial test and measurement. Usually a work-piece is measured mostly by a larger aperture system, whose aperture is not smaller than the work-piece. To a large work-piece, however, it is not practical to make so large an aperture and to keep accurate. A novel method named One Point and One Line (OPOL) working on 2D image connection is proposed here, through which parts of images about the work-piece sampled at first can be connected by the computer so that a total image containing abundant information should come into being. And on the basis of the total image, all of the measuring tasks are carried out quickly and efficiently by pre0established manmade feature objects and implementing subpixel analysis based on polynomial interpolation and polyfitting.
Fast integrated multiparameter detecting system for shaft parts
Meirong Zhao,
Yuchi Lin
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The principle and method of realizing fast and integrated detection for the geometrical parameters of shaft part are discussed in this paper. Several sensors controlled by a computer are used to detect the measured work-piece in photoelectric scanning non-contact mode in this system. Multi parameters of axial and radial directions could be acquired simultaneously during one scanning process. To achieve fast detection of two dimensions, a scanning signal sensor composed of diode laser and photoelectric component and a grating transducer are adopted in the axial measurement, and a laser displacement transducer based on photoelectric triangulation method is utilized in radial measurement. The normal detecting velocity of the system is 2 seconds per piece; the axial measuring accuracy is less than 0.01mm and the radial one is less than 0.04mm. The structure, the principle and the relations among each part of the system are analyzed and the results of practical measurement are provided in this paper.
Defect inspection in optical fibers based on a quasi-joint transform correlator
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A hybrid opto-electronic optical fiber inspection system based on a quasi-joint transform correlator is proposed. The system can overcome the drawback of the overall small size of the joint transform spectrum in a conventional JTC. Experiment results show the system can successfully perform the defect detection of optical fibers. Furthermore, it has higher discrimination comparing with the conventional JTC.
Mapping matrices and weight function in high-precision EST of flatness by optical probe
Maisheng Hong,
Yuanlei Wei,
Zijun Li,
et al.
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As one of the valid means to perform non-contact high-precision measurements, many types of measuring sensors are developed by professor S. Kyono, which are based on laser optical triangular method and have many compound modes of displacement and angular displacement, such as one-point-one-dimension and one-point-2- dimension, and used in flatness measurement. Based on the uniform equations of 1-dimension and multi-dimension EST (Error Separation Techniques) and their mapping matrixes, which are proposed by the author, this paper expounds the same ultimate source of displacement and angular displacement in spite of their different forms. The above is based on the linear decompositions of flatness measurement equations on two directions of orthogonal coordinates. According to the theory, ten methods of flatness EST are investigated. And their mapping matrixes and weight functions are analyzed. At last their virtues, defects and their application situations are compared.
Fiber optic sensors for safety control of civil structures
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The development of fiber optic sensors for safety control of civil structures is over viewed in this paper. Main principle of fiber optic sensors such as Fiber Bragg Grating sensors, fiber F- P sensors and low coherent fiber Michelson interferometer is discussed. Some typical applications of fiber optic sensors in bridges, buildings and etc. are provided. The tendency of fiber optic sensors is forecasted.
Detection and estimation of signal time of arrival (TOA) for wireless location based on mobile telecommunication network
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Today wireless location is not only one of the ten hot telecommunication technologies, but also one of the important supporting technologies in the third generation mobile telecommunication. In the paper, the principle of TOA location and the essentiality of the measurement of signal time of arrival (TOA) for wireless location are pointed out first, then detection and estimation of time of arrival (TOA) of random signal is mainly expounded and the performance of signal estimation is assessed. So the theory basis is provided for research and development of wireless location in the third generation mobile telecommunication system.
Fast algorithm of calculating invariant features for image matching
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Image matching method is an important technique in image processing. It gives reference and methodology to fully use different kinds of data. An image matching method based on invariant features of image and image data basis generating method are presented in this paper. The method is realized by following procedures: first, we establish the image data basis, then we change the newly obtained image to the scale of the base image, and finally we use invariant features of image to correlate the base image and the newly obtained image, in this way to find the best matching point. At the same time, a fast algorithm is introduced in this paper to calculate the invariant features of image. The method is insensitive to translation, rotation and scale, also it is simple and stable.
Adaptive Sobel operator and its uses
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As we know, a main problem in image classification and explanations the segmentation of image. Use of the boundary contour rather than most of other preprocessed data help in simpler image representation, registration, and identification. Thus the problems of edge detection and contour following have been widely addressed with proposed solutions ranging over simple thresholding, signal processing, filtering techniques, and definition of admissible edge profile function, etc. Most of these techniques seem to be complex and time consuming. To solve the conflict between noise and time consume, this paper presents a fast method for detecting the contour of images. It consists of three steps: first, reduce the image noise by using a high frequency noise sensitive smoothing operator; second, detect the edge by using an algorithm based on modified Sobel operator; and third, follow the boundary contour and determine the area of interesting in the image. The results of experiment show that the method is fast and accurate.
Computer control system based on fuzzy control for boilers
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According tp the features of the combustion process of boiler the optimization of combustion is implemented by using fuzzy control principle. The paper states a control strategy implementing different control regulation in different phases (coarse, fine and precision tuning) for enhancing the thermal efficiency of combustion of boiler. The practice shows that the thermal efficiency increased 2.8%.
Minimum stable speed for Ground Servo System launching laser beam to interfere with an air target
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First, the stationary time is calculated, and accordingly, the minimum stable speed or the speed resolving power of the Ground Servo System is discussed. Through simulation we analyze the interfering result and tracking effect.
Low-speed jitter adaptive control in an optoelectronic tracking system
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Model Reference Adaptive Control (MRAC) technique is applied to our practical optoelectronic tracking system. Comparing with tradition corrective method, MRAC effectively increases the tracking precision when the system works in low speed area. The low speed jitter phenomenon is decreased obviously.
Chaos self-adapting parameter modulate system based on electro-optics device
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This article make used of the Electro-Optics device to research chaotic phenomenon and their self-adapting parameter modulate system. Self-adapting parameter modulation system main is given priority to electronic modulation. It given some chaos equation of parameter modulation and analyze signal waves to self adapting change rule of the detection for measuring instrument- exterior modulate inject electronic parameter into phot-electricity system in this paper.
Electronic parameter modulate hyperchaos system based on semiconductor laser
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It is based on the semiconductor laser that design and researched hyperchaos feed back system with electronic modulate in this paper. The system adopted multidimensional and cascades connection manner to constitute modularization: it also may increase or reduce when it is needed. The paper takes to theory analysis and practice hyperchaos experiment about system, and carry through some electronic parameter modulate and wave spectrum analysis, it has definite practicality.
Method of real-time control and data processing of the laser roundness instrument
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In this paper, the methods of real-time control and data processing are presented, which is used to measure the roundness error (RE) of rotating parts on production spot. The non-contact measurement of RE for different section can be realized by using the rotational and axial feed servo control system. It has many features such as high speed, high precision and non-contact automatic measurement, etc. Its main specifications are follows: measuring range is supper to (Phi) 500mm, resolution is 1 micrometers , repeatability is +/- 0.5micrometers . The working principle and overall structure are briefly described, the methods of the separation of eccentric error caused by installing the part and the computer real-time control and data processing are discussed in detail.
Fault diagnosis method using network and fuzziness
Tong Song,
Baoqiang Song,
Qiong Fu
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This paper presents the fault diagnostic method using neural network and fuzziness of sensor readings. Neural network trains the data of abnormal patterns are acquired from the fault tree. And sensor readings are processed by membership functions. In diagnosis, attaching factor is inputted in neural network, then the cause of process malfunction is inferred. A pilot plant is used to demonstrate the effectiveness of proposal method.
Development of research on super-precision measurement techniques for circle and cylindrical contour
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At the beginning, it is presented that several theoretical and key technique problems among super-precision and nanometer measurement for circle and cylindrical contour, including: periodic reappearance of straight line datum movement; harmonic suppression in the measurement for circle contour; datum error's recognition and separation in the measurement for cylindrical contour; the problem of information integrality in the measurement for cylindrical contour. Then it is mainly introduced that the development research of super-precision measurement for circle and cylindrical contour, including: error separation technology with non-harmonic suppression; laser monitoring technology of straight line datum movement; error separation technology among datums, etc. Finally, give a vista of new promising measurement technique, such as the contour measurement based on confocal microscopy, optical measuring techniques with non-datums and so on.
Optical probe using differential confocal technique for surface profile
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A non-contact optical probe for surface profiling with up to 2nm position resolution over 100micrometers measurement range has been developed, which includes a confocal light path for non-contact position and a capacitance sensor for Z axis displacement measurement. The principle of the optical probe is based on differential confocal technique. The differential light- intensity distribution depends on the confocal axial response (or depth discrimination) properties. Using the diffraction theory, the mathematical analysis of the method has been performed. Validity of the mathematical theory analysis of the differential confocal technique is experimentally verified.
Optical fiber interference target flowmeter II: damper design
Zhengnai Sun,
Pengsheng Li,
Xifu Qiang,
et al.
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Optical fiber interference target flowmeter. In this paper theories of the flowmeter and its damper are demonstrated, the structure of the damper is given. Experiments have been done to study the relationship between damping index and clearance, relationship between clearance and viscosity under a fix damping index, relationship between damping index and viscosity under three kinds of clearance. The experimental results showed that the designed damping system could slow down deformation speed of a cantilever used in flowmeter and, furthermore, slow down the drifting speed of interference fringes. This will cut down cost of the interference flowmeter.
Visual servo control system of space robot
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Through the study of 3D information acquisition technique, this paper proposed an experiment system for robot eye-in-hand vision 3D information acquisition. The system adopts to a singer camera, and realizes object space 3D information through the detection to object for PUMA562 robot system. This system has been successfully implied in space robot system and intelligent grippers.
Auto-testing system for measuring optic characteristics of vehicular lamp
Yongmei Zheng,
Feng Gu,
Xuanguo Shen
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The paper presents a new auto-testing system for detection of photometry quantity and chromatic characteristics of vehicular lamp. The system, according to the national standard, can automatically and accurately inspect illumination, chromaticity, luminous flux and luminous intensity. The system consists of one mechanical turning table and two instruments, controlling by computer. The turning table has high precision with 0.01 degree(s) resolution. The illumination meter can be automatic range-change, completely adaptable for automatic acquisition by computer. Using precious grating spectrometer, CCD signal processing and optic fiber probe, the colorimeter can accurately inspect the tri-stimulus value, chromaticity coordinate and spectral radiant intensity. The testing repeatability is under 0.35%. The system realizes digital display and controls by computer. The system has been used in vehicular lamp factory and testified satisfactory performance.
Fast 3D measurement method for multibeam confocal system and system error calibrating
Bing Kong,
Zhao Wang,
Yushan Tan,
et al.
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The multi-beam confocal system has been an important 3D measurement because of its peculiarity of non-contact, high precision and high speed. In this paper, an interpolation technique is studied, and a fast method to get the 3D profile adapted to the multi-beam confocal system is inferred. Compared with the usual method, the fast method uses more sampling information, so higher precision can be gotten at the given sampling distance. Theoretic analysis shows that 1 micron measurement precision can be reached while the axial sampling distance is 22 micron and NA is 0.12. However, since large angular field is used, the focal plan of the system is concave and the curve degree is often larger than measurement precision, unless the system must be designed strictly. Conicoid fitting technique is adopted to calibrate the error, and experiment indicated the method is useful for error revision.
Multisensor image fusion based on wavelet transform
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In this paper, a pixel level multi-resolution image fusion scheme based on wavelet transform is described. In the fusion process, the images are first decomposed based on wavelet transform. Then at each resolution the images are fused. Finally the fused image is obtained by taking the inverse wavelet transform of the fused wavelet coefficients. With the aim of reducing the contrast and structural distortion, when construct each wavelet coefficient for the fused image, we consider not only the corresponding coefficients, but also their close neighbors. Both visual quality (contrast and presence of fine details) and absence of impairments or artifacts are concerned in our method. This approach has been successfully used in image fusion. The experimental results show that the fusion scheme is effectual and the fused images are more suitable for human visual or machine perception.
Fuzzy feature matching between radar image and optical image
Tiejun Li,
Xin Ma,
Zhe Chen,
et al.
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In this paper, imaging information and feature of radar image and optical image are investigated firstly, and fuzzy feature extraction of image is presented. Then relationship between two images is described. Through analyzing the images, a new knowledge-based fuzzy feature matching algorithm is proposed. Experiment result shows that proposed fuzzy feature matching approach is correct and reliable.
Estimation of navigation parameters from real-time aerial scene
Tiejun Li,
Zhe Chen,
Zhun Liu,
et al.
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In this paper, and estimation method for navigation parameter using real-time aerial scene (RTAS) is presented, where navigation parameters represent the position and velocity information of an aircraft for autonomous navigation. The proposed method is composed of relative position estimation and absolute position estimation. Stereo photogrammetry is introduced and matching between RTAS and RTAS is processed in relative position estimation. Digital image reference map (DIRM) is employed and matching between RTAS and DIRM is processed in absolute position estimation. Experiment result shows that our proposed navigation parameter estimation is accurate and feasible.
Analysis of the effect on electron density along the laser path by adding magnetic field in laser beam welding
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In this paper, the electron rotating radius and the corresponding length above surface of the workpiece where the electron density is notably reduced are calculated on the condition of adding magnetic field in laser welding according to the temperature of plasma and the average velocity of electron motion. The experiments results indicate that on the set condition, the weld area is increased by 18% with the weld penetration and the melting efficiency being increased by 22% and 13% respectively when the magnetic flux density added is set at 96 mT.
Computer platform for the analysis of the process of laser welding
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This research project aims at establishing a computer platform especially for the analysis of process of laser welding. After the laser induced plasma photographs, metallographic photographs of the weld are scanned into computer and the welding parameters are input, the results of the analysis can be obtained by means of selecting different function-keys. The main results of analysis include: the solid angle of spatter distribution, the velocity of the unit volume spatter, the area of the weld, the penetration-to-width ratio of the weld, the included angle of side boundary line of the weld, the RGB chart and the grey isothermal chart of plasma and the area of laser welding plasma in the different temperature district and so on.
Phase unwrapping algorithm based on fringe density analysis in Fourier transform profilometry
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A new phase unwrapping algorithm based on fringe frequency analysis in Fourier Transform Profilometry (FTP) is presented. By the frequency weighted filtering, the analysis of fringe density is converted into the analysis of fringe modulation. And based on ordering this filtered fringe modulation, a more optimized phase unwrapping path can be found out. The consequent phase unwrapping path is always along the direction from an area in which local spatial frequency is less further from the fundamental frequency to one in which local spatial frequency is more further from the fundamental frequency. The experiment shows that the new phase unwrapping algorithm is reasonable and effective. Even in the worse case the error is limited, if there is any, to local minimum areas.
Fourier transform profilometry for dynamic 3D shape
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In this paper, we propose a method for dynamic 3D shape measurement based on Fourier transform profilometry. We also study the algorithm of phase difference between two deformed fringes and 3D phase unwrapping method based on phase difference.
Binary coded grating with error diffusion and its application in 3D sensing
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With the development of computer technology and CCD sensor, 3D sensing with sinusoidal structure illumination are widely used. To obtain the shape information of a 3D object, a procedure called spatial modulation-demodulation is performed. In most practical methods such as PMP, FTP, SPD or MMP, sinusoidal structured illumination is utilized as the carrier of spatial modulation, and the quality of it plays an important role in the measurement result. But it is very difficult to produce a perfect sinusoidal grating. The idea of Error Diffusion algorithm is first used to produce a better sinusoidal illumination structure. 1D and 2D sinusoidal module is designed. A computer simulation system base on PMP model is established to implement Error Diffusion modulation to structured light field. Computer simulations have verified the efficiency of Error Diffusion grating.
New algorithm for fuzzy biomedical image segmentation
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In this paper, a novel stepwise thresholding is first addressed. Then the design of intensity homogeneity segmentation criteria is presented. Some examples of the experiment results of fuzzy image segmentation by the method are given at the end.
Core image acquiring and processing
Jianzhong Long,
Daisheng Luo,
Deyuan Tao,
et al.
Show abstract
This system is a mechanical-electric integrative apparatus used in the scanning of core. It can form white-light or fluorescence images. It can rotationally scan cylindrical core and translatorily scan section plane of core. It can also actualize the acquisition, edition and processing of these images, and store them in the image library in compressed format. After inputting a special parameter, for example the well serial number, users can see the white-light and fluorescence images changing with the well depth. Then users can analyze the bedding type with the white-light image and the oil distribution with fluorescence image. And this system can calculate all kinds of parameters and form synthesized database with other data.
Distributed optical fiber strain sensor based on a novel microbend structure
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The distributed strain sensor has significant application in real-time monitoring of the status of large and important engineering structures such as bridges and dams. In this paper, a quasi-distributed optical fiber sensor system is set up using OTDR technique. The strain sensors that base on a novel microbend configuration are designed and used to measure the local strains along the optical fiber. In experimental studies, we are concerned about two questions: the monitoring of the safety status and the strain measurement of the member to be measured. The experimental results are given.
Fusion in frequency-domain of instantaneous laser assistant vision image and low-light-level image
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The area of low light level (LLL) night vision, improving the LLL image quality by using infrared laser assistant vision technology has been proposed as an important subject. In this paper, we realized the fusion of the instantaneous laser assistant vision image and LLL image in frequency-domain. The features of the two kinds of images are different because the spectrums they respond are different. In frequency-domain, we assign different threshold of the high and the low frequency in order to realize the fusion processing. The details and the contours of the scene are enhanced respectively. The experiment results show that the fusion of instantaneous laser assistant vision infrared image and LLL image can improve the image quality effectively. The fused images and the source images are presented in this paper.
Optimizing design of servo control in Infrared Search and Track (IRST) systems
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Servo system is an important part of an Infrared Search and Track (IRST) system in a fighter plane, which includes scanning mechanisms, racemic mechanism, focusing mechanism, aperture adjuster, shaking-mirror modulator and system control software. This paper firstly describes the servo system of the IRST system, and then lays emphasis on design of control method. An intelligent controller is given and its parameters are defined. Finally the result is presented to demonstrate the effectiveness of this design.
DDGIPS: a general image processing system in robot vision
Yuan Tian,
Jun Ying,
Xiuqing Ye,
et al.
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Real-Time Image Processing is the key work in robot vision. With the limitation of the hardware technique, many algorithm-oriented firmware systems were designed in the past. But their architectures were not flexible enough to achieve a multi- algorithm development system. Because of the rapid development of microelectronics technique, many high performance DSP chips and high density FPGA chips have come to life, and this makes it possible to construct a more flexible architecture in real-time image processing system. In this paper, a Double DSP General Image Processing System (DDGIPS) is concerned. We try to construct a two-DSP-based FPGA-computational system with two TMS320C6201s. The TMS320C6x devices are fixed-point processors based on the advanced VLIW CPU, which has eight functional units, including two multipliers and six arithmetic logic units. These features make C6x a good candidate for a general purpose system. In our system, the two TMS320C6210s each has a local memory space, and they also have a shared system memory space which enable them to intercommunicate and exchange data efficiently. At the same time, they can be directly interconnected in star- shaped architecture. All of these are under the control of FPGA group. As the core of the system, FPGA plays a very important role: it takes charge of DPS control, DSP communication, memory space access arbitration and the communication between the system and the host machine. And taking advantage of reconfiguring FPGA, all of the interconnection between the two DSP or between DSP and FPGA can be changed. In this way, users can easily rebuild the real-time image processing system according to the data stream and the task of the application and gain great flexibility.
Pulsed laser/background light simulator
Yi Yang,
Xuxiang Ni,
Zukang Lu,
et al.
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In this paper a pulsed laser/background simulator used for debugging and testing system performance of laser range finer (LRF) is introduced. This simulator is composed of a 1064nm- laser diode, an iodine tungsten lamp and its power supply, a collimating optics system, drive circuit, synchronal and delay circuit, simulating and computing code. This simulator can simulate the laser echo signal and the background radiation of a pulsed LRF when LRF ranges target with different distances and different characteristics under various atmosphere conditions.
New soft-measuring system of polarized light
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In the paper, the polarized light signal is analyzed in theory and a corresponding mathematical model is established. The collected data are dealt with the least-squares-fitting, and so the polarization vector is obtained. The high precision may be obtained, and the digit of A/D converter and the accuracy of the modulating frequency are key factors. The measuring system with a simplified mechanical and electrical structure is presented in the paper. The system is adapted for the rapid and long-distance measuring.
Low-power optoelectronic count
Wenqing Fang,
Tuanqing Fang
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This paper will tell how to use optoelectronic sensor for count when powered by battery, how to count correctly, how to check sensor state and how to judge rotary direction.
Simple image subtraction using phase shift property of photorefractive two-wave mixing
Luzhong Cai,
Yurong Wang
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A simple image subtraction technique with photorefractive real- time holographic interferometry is analyzed and experimentally demonstrated, where the (pi) phase difference between the two images to be subtracted is automatically introduced by the phase shift of reconstructed wave from the incident wave in two wave coupling process. Its performance and requirements for a good result are discussed.
Three-dimensional view based on RS and GIS: three-dimensional simulation of Mount Taishan
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It has not been satisfied with the need of visualization by 2D RS(remote sensing)image. The 3D simulation overlapped with RS image can reflect land forms more directly. This article is to simulate the Mount Taishan, which is world famous natural and cultural heritage, in 3D on the basis of RS and GIS for adapting to the developing of society. First generating DEM, then the TM image is overlaid DEM data and is shown in 3D with the 3D technique of ER mapper. This study takes guidance action on tour planning of Mount Taishan and tourists visiting the Mount Taishan.
Software solution to counting and subdivision of moire fringes with wide dynamic range
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A kind of software solution is provided to implement counting and division of moire fringes in this paper. No complex electronic circuit of digital counter exists in the digital reader that adopts this software solution. The counting and division of the fringes are completed in DSP (digital signal processor), so it can solve the problems that counting circuit can't match the subdivision system properly by logical judgement. Because of utilizing high-speed optoelectronic convertor and flash sample technique, the system can process moire signal with wide frequency range. The example demonstrated in the paper can count and divide signals from DC to 1MHz, i.e., if the optical sensitivity of the signal is 1 fringe per micrometers , the fastest measure speed can reach 1000mm/s. The experimental result shows that the software solution has high accuracy and sound reliability.
Reflective fiber optic displacement sensor with intensity compensation
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A reflective displacement sensor utilizing three fibers, one transmitting and two receiving with different core diameters, is described in this paper. On the basis of optical field distribution of multimode fiber, the intensity compensation mechanism of this sensor is analyzed in great detail, at the same time the displacement modulating functions and corresponding simulating carves are presented. Results show that this sensor can effectively compensate for variations in the source intensity, for losses in the optical fibers, and for variations in the reflectivity of the reflector surface.
Effect on intensity modulation caused by perpendicularity between the axes of fiber pair and reflector
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Although there are lots of research papers on the intensity modulated fiber sensors, a very important problem is always neglected, which is the effect on the intensity modulation caused by perpendicularity between the axes of fiber pair and the reflector. Though several papers gave some literal description that the axes of fiber pair should be perpendicular to the reflector, few of them put forward a precise model and quantitative analysis. Just thinking about this, the mathematical model on this effect is established. The simulation curves with different obliquity of the reflector are computed and plotted. Results show that the obliquity of reflector has great influence on modulation function. So advice is presented that the axes of fiber pair should be perpendicular to the reflector.
Wide-range and high-resolution displacement measurement with grating
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A new method of displacement measurement using single grating is put forward in the paper. Wide range and high-resolution displacement measurement is realized by means of a general coarse metric-grating and a spectroscope. The method solves the traditional problem that high frequency grating can't be manufactured too long. The optical configuration and the principle of measurement are presented in the paper. Its feasibility is proved by experiment. In the experiment, a metric-grating with frequency of 50 rulings/mm is used and optical subdivision more than 32 is received.
Camera calibration in augumented reality
Yunhao Li,
Maojun Zhang,
Yue Qi,
et al.
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One of the key issues of Augmented Reality (AR) is the camera calibration. In AR applications, camera calibration has some special requirements; it prefers good registration of virtual objects in real environment to high precision. We propose a flexible and robust technique to calibrate the camera, it is well suited for augmented reality applications. This technique only requires the camera to observe a planar pattern, e.g. a normal wall. The proposed procedure consists of a closed-form solution, followed by a nonlinear refinement based on the maximum likelihood criterion. We have tested out proposed technique in the real environment, and have obtained very good results. Detailed analysis is also included in this paper. Compared with classical techniques which use expensive equipment such as two or three orthogonal planes, our technique is easy to use and flexible.
Feature matching and improved Hough transform in visible measurement
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This paper presents a new idea of Epipolar Slope. There are some feature points, e.g. the inflection point, on the epipolar line or curve. The homonymous points can be discovered in a couple images, and Feature Matching can be achieved as visible measurement. The Improved Hough Transform has been discussed in this paper because the standard quadratic curve may be discovered by the Improved Hough Transform as the pre-process of the Feature Matching.
New image matching method based on principal component analysis
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This paper introduces principal component analysis into matching and correlation tracking, and presents a matching algorithm based on principal component analysis. This matching method can bear some image distortions in the image matching and visual tracking. Experimental results are presented to support it.
Distance inspection for robot vision and 3D imaging using defocusing pixel dither
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The object distance is the important parameter for image recognition and robot 3D view. This paper presents a novel method of pixel dither passive ranging. We derived the mathematical model of ranging, obtains the ranging mirror equation using lens equation, and analyzed the effect of light spectrum wide and the limit for demodulation. It shows that this method has the performances of high precision, high sensitivity and good anti-interference. In the process of ranging, it is not necessary to require the detector plane on the imaging plane exactly.
Development and industrial solutions of laser marking with a model on escutcheon of section bar
Pu Zhang
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The section bar escutcheon is the basic mark of steel products. It contains the name of the manufacturer, material quality, standard, production date and serial number of product, which are used for recognizing the bar in the process of using, transporting and marketing it. The marking method existed cannot meet practical requirements of preserving the escutcheon for a long time. As a result of researching in this field, the author has worked out anew method of marking and invented a laser marker of the section bar escutcheon. It is a computer-controlled integrated system composed of a club-shaped Nd-doped yttrium aluminum garnet (Nd3$plu:YAG) solid laser (Kr light pump), a continuous solid laser power source, an optical scanning system, a controlling computer and a cooling system. The optical scanning system guides the output laser beam to the surface of escutcheon blank by using a special controlling system with a mechanism called the planar large pitch ball-leading screw, driven by a stepping moto. Each escutcheon blank will be sent to the pointed location of the focus plane by a pneumatic deferent mechanism composed of tow cylinders. Alternative operation of two cylinders will respectively complete the input of the aluminum escutcheon blank and output of the aluminum escutcheon. The rat cage industrial controlling computer has been applied. Apart from controlling the work of hardware and alarms, this system has many other functions such as recording, processing, transferring, inquiring the product data through a network; recording, reporting the time interval of production break or stop. The data such as the temperature, water, electricity and gas supplies at the site of marking will also be recorded. The prerequisite of running such a laser marker is that the cooling system must work well. For that reason, a hydraulic pressure annunciator has been integrated into this system.
Stereoscopic neurovision system for part recognition in intelligent assembly system
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In this paper, a new 3D recognition method for intelligent assembly system is presented. In this method neural network technology is used to provide new methodologies for solving difficult computational problems in 3D recognition processes. The method can be divided into two parts. In the first part, phase based stereo matching techniques are used to find the correspondence between left and right image in stereo image pair. The Hopfield neural network is established, so that the computation can be implemented efficiently in parallel. A 3D object reconstruction neural network is constructed by using BP neural network. With the results of stereo matching, the 3D configuration and shape can be reconstructed. In the second part, the feature vector of 3D object is constructed by using 3D moment and its invariant. With the results obtained in first parts, ART2 neural network is adopted for neural network classifier. With the ART2 neural network classifier, the 3D objects can be recognized and classified. The method is tested with both synthetic and real parts in intelligent assembly system. Good results are obtained. It is proved through the experiments and actual applications that the method presented in this paper is correct and reliable. It is very suitable for intelligent assembly system.
Imaging projection lens for excimer laser micromachining
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In accordance with the practical demand for excimer laser micro- machining technology, an imaging projection lens with a resolution of 2micrometers is designed and produced. Through the practical micro-machining test, the lens achieves the designed specifications and could be put into practical use.
Measurement of high-power laser resonator mirror's misalignment using PSD
Lingxiang Zhang,
Lei Fu,
Hongmin Shi,
et al.
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PSD is the abbreviation of position sensitive detector, which can transform the light spot position on sensitive surface into photocurrent. Based on the structure, there are on-dimension PSD and two-dimension PSD. Recently PSD is mainly used in the position sensor based on the principle of optical triangulation. We use it as sensor in the control system of high-power laser resonator mirrors' misalignment in order to improve the quality of laser pattern. In this paper, we discuss the system, the theoretical model, the angle magnification technology, the control circuit of sensor signal, and the control executive part in details. At last, we introduce the experimental result.
New progress in shearography
Hong-Min Shi,
Shouyong Ni,
Lei Fu,
et al.
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As common-path interferometers, shearography (shear interferometer) has been widely used in many fields. It has some special advantages as well as some disadvantages. This leads to the result that it can only be used in some special conditions for some special uses. Int his paper, both the advantages and the disadvantages are discussed. Some new progress, such as the phase-shift in shearography, two-dimensional shearography and the phot-carrier in shearography, are proposed. All of these new progress are developed in the aim of extending the application fields, improving the processing accuracy and realizing automatic measurement.
Characteristic models of a new structural LVDT
Wei Zhou,
Guoqiang Lu,
Ping Cai,
et al.
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In this paper the magnetic field distribution of solenoid is analyzed when the core moves along with the displacement of the object and an important substantial nonlinear error source is found. Based on the analysis, a new structural LVDT is designed which generates an even segment in its magnetic field distribution. This even segment doesn't change when the core moves along with the displacement of the object and thus the nonlinear error can be theoretically avoided. The basic experiments have proved that the nonlinear error of this new structure transformer is much smaller than the traditional one with same dimensions. In the second part of this paper, characteristic models of this new structure LVDT have been given which are the basis of further designing its parameters.
Calibration of angle function in angle-grid-based 2D-position measurement system
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In angle grid based 2D-position measurement system, building up an accurate correspondence between the angle and the coordinates for the angle grid is very important to ensure the final accuracy of the measurement system. This paper introduces a calibration method for the angle function so as to realize the software datum. After introduce the iteration calibration algorithm, the convergence of the algorithm is discussed in detail and is proved analytically. Digital simulation has confirmed the calibration algorithm.
Laser alignment system used for coaxiality measurement of large-scale holes
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A single mode fiber (SMF) pigtailed laser diode alignment system used for coaxiality measurement of large scale holes is studied. The drift of angle of laser beam is restricted obviously by mode restriction of single mode fiber. The stability of laser reference line is the order of 1.5 x 10-6. It can be used in measurements of position and form errors of large scale workpieces.
Process control by computer in laser processing system
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By studying the applications of the computer in laser processing system, this paper analyzes how to input images to laser processing system, deals with images, outputs images, controls the process and accepts the system feedback in laser processing system. Laser process is working by laser energy. The responding of laser power supply, the focus of laser etc. will affect the precision in laser process, so we carry out a proper project by building laser process feedback system and using software to correct the problem in laser process that are collected by the feedback system. We think a better result will be achieved in this way.
Decomposition of mixed pixels based on Gray System Theory
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After analyzing existing methods of decomposition of mixed pixels in remote sensing images, this paper introduces briefly Gray System Theory, and presents a new method of decomposition of mixed pixels based on Gray System Theory. The experiments demonstrate the method and give satisfactory results.
Automatic inspection of geometric accuracy of optical fiber ferrules by machine vision
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We present an automatic inspection system developed to evaluate the geometric tolerance of the optical fiber connectors to a dimensional accuracy of 0.1 micron. The main part of the inspection system comprises a series of machine vision devices and laser scanning probes to measure the internal and external circle diameters along with their concentricity by making the most of advanced digital edge detection algorithms. Actual experimental results obtained through various repeatability tests demonstrate that the developed system well satisfies the required industrial demands for in-situ inspection of optical fiber connectors in real manufacturing environment.
Seal imprint recognition with joint transform correlators
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In many commercial applications in Chinese society, seals instead of signatures for person identification are widely used, such as money withdrawing lists, checks, receipts, etc. It needs high rate of correctness. However, it can not be effective if the process of safety validation is inspected merely by human eyes. Also, for safe control and management, in addition to the potential human cheating act, there is also a possible error due to human neglect. Based on the constrained energy minimization joint transform correlator (CEMJTC), we have proposed a prototype Chinese seal recognition system, which combines the advantage of light speed and programmability of computer. The CEM filter designed for optical correlator has the desirable property of sharp peak with low sidelobes levels in the output correlation plane. Th major advantages of the system are alignment simplicity, rotation invariant capability, high discrimination capability and suitability for hybrid optical signal processing.
Three-dimensional laser inverse scattering phase method for evaluating microstructure
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The 3D laser inverse scattering phase method offers the advantage of measuring a 3D microprofile within the whole area illuminated by laser beam at one time. No scanning process is required as you see in SPM (Scanning Probe Microscope). So, this method finds application where the in-process measurement of a 3D microprofile with accuracy in the nanometer order is required for the process error evaluation. The work reported in this paper deals with development of a new iterative Fourier phase retrieval algorithm based on practical object-domain constraints and actual measurements of a NIST traceable surface topography reference with rectangular pockets 44nm deep at intervals of 10micrometers . The results obtained in the measurements show the validity of the newly developed laser inverse scattering phase method.
Vision-based precision inspection system for profile and performance of small and micro gears using intelligent image processing techniques and virtual master gears
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As the product size become smaller, much smaller sized parts are increasingly required in many products fabrication such as cameras, camcorders, and electric appliances, etc. Small or micro gears whose sizes are about few hundred micrometers to few millimeters have been greatly required for the above products, as they become most efficient parts for power transmission. The small of micro gears are prone to geometrical and functioning inaccuracy during the micro fabrication processes, and thus the measurement system has been desired for the geometry and performance checking of gears. In this paper, a precision inspection system is developed for the gear checking, consisting of the optical vision microscope, vision image processing modules with subpixel accuracy, and the profile inspection software using the virtual master jigs/gears mathematically generated. For accurate analysis of the gear geometry from the captured gear image through the optical vision system, a highly accurate vision image processing algorithm has been implemented, where two dimensional subpixelling technique is developed having about one tenth subpixel accuracy. A mathematically generated mater gears/jigs are implemented: several core parameters of the gear profile are calculated from the comparison between the virtual master and the measured gears. Virtual precision ball jigs are simulated between gear teeth profile, and thus the runout parameter can be successfully evaluated from the virtual jig movement on the gear teeth image. The eccentricity parameters can also be calculated from the sinusoidal fitting of the virtual ball movement. The development precision inspection system for small or micro gears has been applied to practical gears of various range, and the essential gear parameters are successfully measured with sub micrometer accuracy.
Rotational error analysis of turning surface by using software datum
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This paper presents a new method for separate measurement of rotational motion errors and a radius circumference profile of a disc plane in the main rotational axis of a manufacturing machine. This method, called the mixed method, uses three displacement sensors and one angle sensor. By measuring a certain radius circumference of a disc plane using these sensors and applying a calculation technique, it is possible to separate axial motion error, two angular motion errors, and the circumference profile. In the present paper, the principle of the mixed method is examined from the viewpoint of spatial frequency analysis. From this principle, it appears that this new method can measure all spatial frequencies, without omitting any frequency. In contrast, the 3-point method, which has also been as an error separation method, has characteristics whereby some frequencies are inevitably omitted. We also set up a measurement system and performed experiments. The measurement experiments confirmed the separate measurement of the profile and motion errors.
Roundness measurement using angle probes
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To measure roundness errors of cylindrical workpieces and spindle errors of machine tools in on-machine conditions, it is important to separate the roundness error and spindle error from each other. Basically there are two kinds of error separation methods. One is known as the multi-orientation method, and the other is the multi-probe method. Multi-orientations including the step method and the reversal method can separate the spindle error and the roundness error effectively, if the spindle error has good repeatability. Compared with multi-orientation methods, multi-probe methods are more suitable for on-machine measurements, because the repeatability of the spindle error is not necessary. In this paper, we present a new error-separation method using multiple angle probes. In the angular three-probe method, three angle probes are fixed around the workpiece to detect roundness profile and two-dimensional spindle error components simultaneously. The effect of the spindle is canceled in the differential output of the probes and the correct roundness profile can be evaluated from the differential data. In this paper, the principle of the angular three-probe method is described. Experimental results of comparing with the conventional displacement three-probe method are also presented.
In-process force monitoring in diamond turning of micropatterns
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The authors have being working on a new position detection method, which can detect two-dimensional position of an xY stage with a single sensor [1]. Conventionally, position detection is carried out by utilizing either a linear scale or a laser interferometer [2]. Displacement probes like capacitance-type probes or laser displacement probes are also used for position detection in short ranges. Basically, such measuring instruments are for one-dimensional measurement. It is necessary to increase the number of sensors for detecting multi-degree-of-freedom positions. This makes the measuring system complicated and expensive. The uncertainty of measurement could also be increased with the increase of number of sensors. In the new position detection method proposed by the authors, a two-dimensional angle grid and a two-dimensional angle senor are utilized [11. The angle grid has a two-dimensional angular pattern on the surface. The two-dimensional position between the angle grid and the angle sensor in the XY plane can be detected simultaneously from the output of the angle sensor. Since only a single probe is used, the problems in the conventional methods could be overcome. In order to realize this new position measuring system, it is necessary to develop a machining method of the specially designed angle grid. The angle grid has two-dimensional sinusoidal micro-patterns on its surface with a wavelength on the order of several hundreds of microns and an amplitude on the order of several hundreds of nanometers. The micro-pattern should be generated over a large area to ensure the measurement range. A machining system based on diamond turning with the fast tool servo technique [3 has been constructed for generating the micro-patterns. To accurately generate the micro-pattern, it is desired to monitor the machining force in the machining process. In this paper, an instrument was designed and fabricated to monitor the machining forces during diamond turning of such micro-patterns. Instrument design and measurement results are presented.
Diagnosing abnormal operating conditions of rotational machineries and machine tools with physical wavelets
Fumihide Takeda,
Saburo Okada,
Masaaki Imade,
et al.
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Any real-time diagnosis of machinery systems is imperative to prevent their malfunctions. One of such promising diagnoses is first to regard any signal taken from the machinery operation as the time series data. We then think of the series itself expressing the displacement under the influence of an external force F. The time rate variables of the series are velocity V and acceleration A that is proportional to F. Under this force F, if the system makes any changes, its kinetic energy KE also changes. The time rate change of KE is the power PW, which is proportional to the product of V and A. The PW is very sensitive to any subtle change in F that controls the system dynamics. We generalize the method to obtain these physical variables from the time series with physical wavelets. The wavelets are the windows through which we selectively view the series and its rate variables in the frequency region confined within each wavelet width. Any subtle change in F will appear on the selective correlation of V and A. The change in F that may lead to the malfunction of the systems will sometimes start at the order of 0.01%, which is often comparable to adverse noise. Even with this noise, however, the selective correlation will identify the small change leading to the malfunction. It can also predict the abnormal operating condition to control the system adoptively. We further make the physical wavelet orthogonal to each other in order to reconstruct the state space. In the space, we then draw a trajectory from the time series, which will reveal the physical dynamics of the operating conditions. This reconstruction is similar to so called time delay embedding in Chaos analysis. Their bases chosen to reconstruct the state space, however, have no direct physical meaning. An example of the diagnoses and prognoses on a drilling machine tool by using the physical wavelets is discussed in detail.
Roundness measurement and the radial motion measurement based on the 3-point method using the inverse filtering
Eiki Okuyama
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In the field of roundness measurement, the 3-point method is used as the typical software datum to achieve high accuracy beyond the limit caused by the radial motion error of the axis. Furthermore, the 3-point method is applied to the radial motion measurement based on the compensation. This article proposes a novel 3-point method for the radial motion measurement based on the weighting equation and inverse filtering. The transfer function of the 3-point method for the radial motion measurement is the same with the roundness measurement. Some simulations and experiments were done to confirm the proposed method.
Digital fringe projection technique for high-speed 3D shape measurement
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A high-speed phase-shifting technique for 3D shape measurement has been developed and experimented. A Digital Micromirror Device (DMD) based video projector is used to project sinusoidal fringe patterns onto the object surface. Its red, green and blue (RGB) channels are programmed to be sinusoidal fringe patterns with 120-degree phase difference. The projector has a color filter with four segments, RGB and clear, which controls the color of the projected image. When a specific segment is in the light path, the DMD forms the corresponding image of that color. A 24-bit color image is formed when the RGB color channels are sequentially projected in a cycle time of 10 ms. When the color filter in the projector is removed, the DMD still projects the three color channels sequentially, but the actual projected images are now in grayscale. The timing control mechanism of the DMD is studied and a circuit is designed to provide an external timing signal for projection control. When a CCD camera used to capture the fringe patterns is synchronized with the DMD, the individual channels of RGB or the three phase-shifted fringe patterns can be captured in less than 10mn, thus making high- speed phase shifting possible. Experimental results demonstrated the feasibility of this technique for high-speed 3D shape measurement.