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440results about How to "Avoid error accumulation" patented technology

Calibration technology for multiple structured light projected three-dimensional profile measuring heads

The invention relates to a calibration technology for multiple structured light projected three-dimensional profile measuring heads, discloses a technology for calibrating multiple structured light projected three-dimensional profile measuring heads in different directions, which can be used for the quick label-free measurement of an object profile projected by structured light, and belongs to the technical field of optical measurement. In the calibration technology, only a calibration object of a plane with a plurality of calibration patterns is required to be designed and is not required to be manufactured into a high-precision three-dimensional target with known geometrical relationships on all surfaces; and geometrical parameters among all planes of the calibration object can be obtained by a close-range photogrammetry technology to upgrade the calibration object into the three-dimensional target, so the difficulty of machining and maintaining the high-precision three-dimensional target directly is reduced. By utilizing the technology, multiple structured light projected three-dimensional profile measuring heads can be measured from different visual angles in a label-free mode, and point clouds scanned in different directions are unified to one coordinate system automatically, so error accumulation caused by splicing is avoided effectively, and the time of the three-dimensional appearance reconstruction of the object can be shortened.
Owner:SOUTHWEAT UNIV OF SCI & TECH

Tunnel construction informatization dynamic monitoring system and monitoring method thereof

The invention discloses a tunnel construction informatization dynamic monitoring system and a monitoring method thereof. The system comprises an industrial personal computer, a PLC (programmable logic controller) wireless controller, a high-configuration digital camera, a deformation monitoring sensitization part, digital display acquisition equipment, wireless transmission equipment and a dynamic design feedback device. The method includes: 1), controlling commands to be transmitted to the PLC wireless controller by a computer control main station and controlling the digital camera and the digital display acquisition equipment; 2), acquiring internal force monitoring data by the aid of the digital display acquisition equipment; and acquiring a deformation monitoring image via the deformation monitoring sensitization part by the digital camera; 3), transmitting a monitored value to the computer control main station by the aid of the wireless transmission equipment; 4), analyzing results by the computer control main station via a real-time analysis module; and 5), transmitting the analyzed results to the dynamic design feedback device, analyzing relative difference of the really monitored value and a standard value, and early warming in real time by an early warning module. The tunnel construction informatization dynamic monitoring system is scientific, safe and practical, the method is convenient, instant, fast and effective, and safety problems in construction monitoring of tunnels are avoided.
Owner:XI'AN UNIVERSITY OF ARCHITECTURE AND TECHNOLOGY

Method for accurately reconstructing dissimilar material microcosmic finite element grid model on basis of CT (computed tomography) images

The invention provides a method for accurately reconstructing a microcosmic finite element grid model of a dissimilar material on the basis of CT (computed tomography) images. According to the method, sequence CT images are acquired through industrial CT, and micro-structural information in the CT images is mapped onto the reconstructed finite element grid model on basis of digitization and threshold segmentation, so that any detailed structural information in the dissimilar material can be represented in the reconstructed model. The method improves the reconstruction accuracy by means of contrast-limited adaptive histogram equalization, median filtering and pixel interpolation, and improves the reconstruction efficiency through image cut and pixel combination. With the method, rectangular (two-dimensional) and cuboid (three-dimensional) unit grid models with higher finite element analysis accuracy are directly reconstructed, error accumulation during reconstruction, grid partition and other links of the existing geometric reconstruction method is avoided, and reconstruction accuracy and efficiency are improved. The method can be widely applied to fields such as performance prediction and optimization design of dissimilar materials.
Owner:XI AN JIAOTONG UNIV

Automatic extraction method for newly-increased construction land image spots in high-resolution remote sensing images based on NDVI and PanTex index

The invention relates to an automatic extraction method for newly-increased construction land image spots in high-resolution remote sensing images based on the NDVI and the PanTex index. The method includes the first step of inputting a front time phase high-resolution remote sensing image and a back time phase high-resolution remote sensing image, and then conducting geometric fine correction and relative radiation correction, the second step of calculating a front time phase NDVI image, a back time phase NDVI image, a front time phase PanTex image and a back time phase PanTex image, the third step of conducting unsupervised clustering on the two NDVI images and the two PanTex images respectively, the fourth step of extracting a binary change image from vegetation to buildings, bulldozed and filled earth according to the two NDVI clustered images, the fifth step of extracting a binary change image from vegetation, bulldozed and filled earth to the buildings according to the two PanTex clustered images, the sixth step of extracting interfering ground object regions, the seventh step of conducting union operation on the two extracted change images and removing interfering ground object masks to obtain a newly-increased construction land image, the eighth step of segmenting the back time phase images, and the ninth step of calculating the proportion of changed pixels in each segmented image spot and extracting the newly-increased construction land image spots. Through the method, three types of newly-increased construction land image spots can be effectively extracted, and auxiliary information can be provided for land utilization change investigation.
Owner:INST OF REMOTE SENSING & DIGITAL EARTH CHINESE ACADEMY OF SCI +1

Polarized SAR (Synthetic Aperture Radar) image semi-supervised classification method capable of considering characteristic optimization

The invention discloses a polarized SAR (Synthetic Aperture Radar) image semi-supervised classification method capable of considering characteristic optimization. The method comprises the following steps: firstly, adopting a refined polarized LEE filtering method to carry out filtering, extracting polarization characteristics, carrying out combination to obtain an original characteristic set, and carrying out normalization processing; selecting an initial training sample set and a no-label set, and carrying out characteristic selection and classifier parameter optimization through a hybrid coding genetic algorithm under the initial training sample set; reconstructing the training sample set and a no-label sample set; training the classifier, and selecting a candidate set from the no-label sample set; utilizing a trained SVM (Support Vector Machine) classifier to label the candidate set, and selecting and expanding sample points with a high confidence coefficient into the training sample set; repeating the training of the classifier until learning is finished; and classifying the whole image by a finally trained SVM to obtain a classification thematic map. By use of the classification method, on one hand, effective characteristics can be adaptively extracted to improve a semi-supervised classification effect; and on the other hand, the efficiency of self-training learning can be improved, and error accumulation can be effectively avoided.
Owner:HOHAI UNIV

Micro-wave on-wafer testing method based on unknown material substrate

The invention relates to an on-wafer testing method for a micro-wave element based on an unknown material substrate. The method comprises the following steps: firstly, a TRL calibration part, an open circuit resonator and an element to be measured which are suitable for micro-wave on-wafer testing are prepared on a substrate; secondly, a micro-wave on-wafer testing system is calibrated by using a TRL calibration method; thirdly, resonation point of the open circuit resonator is tested by the calibrated micro-wave on-wafer testing system; fourthly, effective dielectric constant and transmission line impedance of the substrate are calculated according to a measured resonation point; fifthly, an S parameter of the element to be measured is measured, and reference impedance of the S parameter is the impedance obtained in the last step; and finally, a reference S parameter with 50 omega impedance is acquired by adopting a method of S parameter impedance conversion. The method has the advantages that the system impedance of the TRL calibration part can be calculated through testing the open circuit resonator; the method combined with standard TRL calibration not only can carry out on-wafer testing on the micro-wave element under the condition that the characteristic of a material is unknown, but also can be combined with a method of field analysis to calculate the real characteristic of the material.
Owner:NO 55 INST CHINA ELECTRONIC SCI & TECHNOLOGYGROUP CO LTD

Oppositely-closing attitude-adjusting method based on multi-laser tracker measuring field

ActiveCN109613519ALess constraints on location selectionFlexible position selection constraintsWave based measurement systemsLight beamGlobal optimization
The invention provides an oppositely-closing attitude-adjusting method based on a multi-laser tracker measuring field. The oppositely-closing attitude-adjusting method comprises the steps that S1, anideal assembly model is established; S2, the multi-laser tracker measuring field is constructed; S3, a bundle adjustment method is adopted for iterative computation, and a homogeneous transformation matrix between any two laser trackers is solved; S4, coordinates of all enhanced reference systems (ERS) under an overall coordination system are calculated; and S5, target workpiece tools are assembled onto standard workpiece tools. Position selection of the ERSs is small in constraint and more flexible, drifting of the relative positions between all the ERSs is avoided, and the measuring precision is improved. Station transferring computation adopts the bundle adjustment method based on an overall optimization idea, station transferring computation between the multiple laser trackers can be completed at a time, and the station transferring precision is improved. Meanwhile, actually measured data of the laser trackers are adopted to guide attitude adjusting, the influence of placing errorof target measuring points on the position estimation result of the target measuring points is reduced, and the measuring precision is improved.
Owner:TSINGHUA UNIV

Multi-starting-point incremental three-dimensional reconstruction method based on large-scale disordered images

The invention discloses a multi-starting-point incremental three-dimensional reconstruction method based on large-scale disordered images. The method comprises the steps of performing image matching, constructing a matching relationship chart, selecting a reconstruction starting point, detecting an edge, performing multi-starting-point three-dimensional reconstruction and splicing a submodel. By means of a clustering strategy and an iteration drift strategy, an image pair which is suitable as starting points is adaptively selected from a disordered image set and reconstruction is performed simultaneously; before reconstruction, determining an optimal reconstruction sub-process of each image according to a layered shortest path first algorithm, and determining a reconstruction boundary; and obtaining a whole three-dimensional reconstruction model according to sub-models obtained in different sub-processes and splicing the common parts contained in the sub-models. The three-dimensional reconstruction method according to the invention has advantages of settling a problem of suspension in reconstruction process when a current scene comprises a plurality of non-overlapped parts, obtaining a whole three-dimensional model which is covered by the image set, preventing three-dimensional structure error caused by matching and transmission of error images, realizing parallel processing in reconstruction sub-process, and improving image reconstruction efficiency.
Owner:HUAZHONG UNIV OF SCI & TECH

Grinding device and method of crankshaft by one clamping

The invention discloses a grinding device of a crankshaft by one clamping, and belongs to the field of crankshaft grinding. Left and right supporting plates are vertically arranged on a rack, and left and right double rotating shaft positioning discs are respectively and coaxially arranged on the left and right supporting plates and are in a cylindrical shape; crankshaft clamping chucks and V-shaped block mounting grooves are arranged on the left and right double rotating shaft positioning discs, and the crankshaft clamping chucks and the double rotating shaft positioning discs are eccentrically arranged; the eccentric distance is equal to the radius of a crank of the crankshaft, and V-shaped blocks are arranged in the V-shaped block mounting grooves; an output shaft of a driving motor is coaxially connected with the right double rotating shaft positioning disc, and an output shaft of a movable indexing mechanism and the crankshaft clamping chuck on the left double rotating shaft positioning disc are coaxial. The invention also discloses a grinding method of the crankshaft by one clamping. The main journal and the rod journal of the crankshaft can be ground only by one clamping without a complicated numerical control system, and the operation is simple; the main journal and the rod journal of the crankshaft are theoretical cylinders, so that the principle error is avoided, and the machining accuracy is improved.
Owner:THYSSENKRUPP ENGINE COMPONENTS (CHINA) CO LTD

Method, device and equipment for detecting and recognizing tire mold character, and storage medium

The invention discloses a method, a device and equipment for detecting and recognizing a tire mold character and a storage medium. The method comprises: inputting a sample of a collected tire mold picture data set into an improved SSD detection network for training, and establishing a character detection model; using a convolutional neural network to extract a feature vector of a character regionimage detected by a character detection model and inputting the feature vector into a long and short time memory network for training to establish a character recognition model; performing target detection on a character detection region of a to-be-detected tire mold image by the character detection model; and outputting a recognition result of a large character or a small character string in thecharacter region by the character recognition model. In the character detection stage, the detection model is established for the characteristics of the tire mold, so as to achieve high detection precision on the mold image. In the character recognition stage, the features are fused in the long and short time memory network after being extracted, and the recognition model is established to realizenon-split and quick recognition of a large character and a small string of an indefinite character length.
Owner:GUANGDONG UNIV OF TECH

Large-power turning and milling composite machine tool

The invention discloses a large-power turning and milling composite machine tool, belongs to the technical field of machine tools, and aims to solve a problem in a traditional composite machine tool that a milling device is only used for auxiliary machining. The key point of the technical scheme is that the large-power turning and milling composite machine tool comprises a lathe bed, a main shaftinstalled on the lathe bed, a back face knife table installed at one side of the main shaft, and the milling device installed at the other side of the main shaft. The milling device comprises a driving mechanism and a milling mechanism rotatably installed on the driving mechanism. The large-power turning and milling composite machine tool is capable of, through installing the milling device with aB-axis on the lathe bed, and enabling the milling device to be rotated in multiple degrees, completing the milling and machining of a complicated workpiece by cooperating with the main shaft, effectively shortening a product manufacturing process chain, improving production efficiency, reducing a clamping frequency of the workpiece, and effectively improving machining precision, and further has the advantages of reducing floor area, and reducing production cost.
Owner:津上精密机床(浙江)有限公司
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