Camera calibration method plays an important role in the stereovision system to resolve the problems of dimensional
measurement of heavy forging. Due to the intensive vibrating, the camera parameters must be calibrated every time after
the action of the water press. This paper presents a method using the scene geometry to calibrate cameras. In the context
of heavy machinery environments, the constraints which can be used are parallelism and orthogonality. These constraints
lead to geometrically intuitive methods to calibrate the cameras. The huge forging equipment such as water press belongs
to geometrically constrained object and insusceptible to vibrating, which gives natural prior knowledge and constraint
conditions for 3-D reconstruction. The method focuses on the calibration of the extrinsic parameters which are subject to
change since the effects of the workspace factors. The intrinsic parameters were calibrated in advance by an off-line
method and were assumed as invariable. The results of simulation experiments demonstrate that the camera parameters
could be calibrated effectively and achieve the real time need.
Stereo matching is one of the most important branches in computer vision. In this paper, an algorithm is proposed for
wide-baseline stereo vision matching. Here, a novel scheme is presented called double topological relationship
consistency (DCTR). The combination of double topological configuration includes the consistency of first topological
relationship (CFTR) and the consistency of second topological relationship (CSTR). It not only sets up a more advanced
model on matching, but discards mismatches by iteratively computing the fitness of the feature matches and overcomes
many problems of traditional methods depending on the powerful invariance to changes in the scale, rotation or
illumination across large view changes and even occlusions. Experimental examples are shown where the two cameras
have been located in very different orientations. Also, epipolar geometry can be recovered using RANSAC by far the
most widely method adopted possibly. By the method, we can obtain correspondences with high precision on wide
baseline matching problems. Finally, the effectiveness and reliability of this method are demonstrated in wide-baseline
experiments on the image pairs.
An edge detection method was developed with capability of objectively detecting significant edges in images of high
temperature forging. The issue of potential image degradation when viewing hot objects was serious concerned. The
paper was absorbed in online dimensional measurement using stereovision technology. Particular characteristics of high
temperature forging were described. A global self-adaptive thresholding preprocessing was used for eliminating most
redundant mill scale regions and segmenting object from complex background. Then, the feature edges was detected and
localized at single pixel scale. Post processing of surround suppression as final additional step was applied to improve
edges detection performance by extracting genuine feature edges from edges map. The entire method was performed on
a real hot forging image and the performance had been proved in experiment result. The approach was specifically
designed for using in online dimensional measurement of heavy forging, but generally enough to be applied to other
edge detection of any high-temperature object.
The gamma ray scattering energy spectrum detected by one detector was presented to distinguish the gas liquid two-phase
flow regime of vertical pipe. The simulation geometries of the gamma ray scattering measurement were built using
Monte Carlo software Geant4. Computer simulations were carried out with homogeneous flow, annular flow and slug
flow. The results show that the scattering energy characters of homogeneous flow and annular flow have significantly
different. The scattering spectrum of slug flow has a little similar to homogeneous flow or annular flow while gas slug
exists too short or too long in measuring cycle. The RBF neural networks were used to predict the flow regime. The
results show that the homogeneous flow and annular flow can be completely distinguished and the mostly slug flows
were exactly recognized by the neural network. It is demonstrated that the method of one detector scattering energy
spectrum has the ability to identify the typical gas liquid flow regime of vertical pipe and fit the applications in
engineering. The void fraction precision was improved by the flow regime compensation.
Based on laser Doppler effect, single section rotational speed of a rotating shaft was measured. By measuring the two sections rotational speed, the difference of the rotational speed between the two could be made. Integrating the rotational speed difference, the relative torsional angle of the two sections under the action of torsional virbration was received, so the rotating shaft torsional vibration was gotten. Non-contact torsional vibration measurement of rotary machine was achieved. The system was designed and the experiment was done on the torsional vibration experiment equipment. The result of experimentation indicate that the relative error between Laser Doppler and conventional torsional vibration measuring method that was less than 0.2%, and the measurement accuracy of Laser Doppler was high.
In this paper, we present a method based on CCD offering the advantages of high sensitivity, no electromagnetic interference and non-contact in order to measure the thickness of the cooler precisely in high temperature and dust atrocious condition online with real-time and reliable parameter for the control system. By analyzing the principle of CCD and the histogram on the grey scale distribution on the layer's image, the thickness measuring model based on the image segmentation method is founded. According to the image characters of clinker layer, both image segmentation and filtering methods before or after the segmentation are selected. The camera cooling system is designed particularly considering the situation where the camera and the clinker cooler work. After analyzing the shortcomings of the measuring method, an improved one named stereopsis thickness measuring method is present, by means of firstly setting up the stereopsis thickness measuring model before determining the homonymic dots recognizing model, then to abstract the characteristic vector to analyze the recognizing method to establish the precise analyzing model, and finally to complete the experimental research of the thickness measurement based on the image segmentation in order to test the feasibility and to show the results to all.
The collimation of the measurement point on the inner and outer diameters of a large workpiece is a key technology in large diameter measurement, and it is a measuring difficulty yet to be well resolved home and abroad. This paper applies highly stabilized light produced by laser collimator to collimate the photoelectric detectors on the two magnetic localize is each adhered to an end of the diameter of the piece, meanwhile, use the interferometer to measure the distance between the center of the two photoelectric detectors, and obtain the diameter by geometric computation. Both the theoretical analysis and the experiment showed that the method is practical, with relatively high precision, and the relative error of the measuring system was less than 5×10-6, which is superior to the traditional mechanical measurement.
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