Machine tools play an important role in the manufacturing industry. The straightness error of the guide rail during machining seriously affects the accuracy of the machine tool, which is usually measured based on the laser collimation principle by the quadrant detector (QD). Laser beam radius varies significantly with long propagation distances. However, the traditional measurement model hardly considers the impact of radius variation. Therefore, an improved straightness measurement model is proposed. The spot radius variation is taken into account in the improved model. Meanwhile, an accurate trajectory equation for the variation of beam radius with distance was quickly established using less measured data. It facilitates faster and more accurate straightness measurements in industrial sites. The feasibility of the improved model is verified at four distances during 5 m. At 3.5 m, the maximum calibration error of the improved model was −1.65 μm, which is 86.8% lower than the traditional model. Meanwhile, the root mean square error of the improved model was 0.7 μm, which was 83.1% lower than the traditional model. The maximum repeatability error of the straightness was 0.28 μm. The straightness measurement accuracy of the improved model is obviously improved at long distances. The improved model would have great potential for long-distance measurement using lasers based on QD.
LNG storage tank is an important storage and measurement tool for LNG, but there is no relevant standard for LNG storage tank capacity measurement.In this paper, a method of measuring the capacity of LNG cryogenic storage tank based on laser measurement technology is proposed. According to the geometry of LNG tank and the characteristics of low temperature operation, a mathematical model is established to solve the problem of LNG tank capacity measurement, which has good practical value.
The method of measuring the weight of cargo with draft gauge is a general method for bulk cargo measurement at sea. However, this method of measuring the draft line value by human eyes is often subjective and has great limitations.At the same time, due to the manufacturing error of the ship, the production deviation of the completion drawing and the correction chart, as well as the influence of the ship deformation, material preparation change, wind wave, hydrology and other factors, the actual accuracy of the draft gauge weight measurement is difficult to guarantee.In this paper, a new method of bulk cargo trade measurement is proposed. Firstly, the UAV is equipped with multi lens camera, and the images before and after unloading are obtained by optical remote sensing technology. Then, according to the highprecision phase control point coordinates of the ship, the whole adjustment of the regional network is carried out by using the beam method to realize the automatic aerial triangulation Dense matching algorithm, automatically matching all the same points in the image, so as to get a large number of 3D point cloud data. Finally, the Irregular Triangulation model of ship hull is constructed by dealunay triangulation methodand.The ship's three-dimensional contour is fitted, and the hull is divided into several sections along the height direction, and the displacement difference before and after unloading is calculated, so as to calculate the ship unloading value. This method can reduce manual measurement error and ship draft error, and improve the accuracy of bulk cargo measurement. It is expected to become a new measurement method for bulk cargo trade.
A large vertical energy storage tank volume measurement system is established based on total station scanning technology, which is the photoelectric measurement technology. The horizontal cross-section area is calculated by point cloud data, and then the volume values corresponding to different liquid level heights are automatically calculated by integrating along the vertical height direction. The system is used to measure a large vertical storage tank with capacity of 100,000 m3. The results show that the system has good repeatability and reproducibility. Compared with the traditional measurement results, the relative deviation of the calculated volume is less than 0.1%. The system meets the measurement requirements of JJG168-2018.The feasibility and validity of the system applied to capacity measurement of large vertical storage tanks are discussed.
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