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The central axis fitting accuracy of the axis rotation method determines the absolute positioning accuracy of the calibrated robot. In this study, two kinds of axis fitting methods are used, and their fitting accuracies are analyzed. The first kind is the traditional fitting method, which fits the measuring point as a circle and uses the normal vector through the center of the circle as the axis of the robot. The second kind is the improved fitting method, which uses the measuring point to fit the sphere and plane, and obtains the intersecting circle of the fitted sphere and plane. In order to avoid the large geometric parameter calibration error caused by the small error of the over-center normal vector in the traditional method, the line of the center of the double intersecting circle is used as the axis of the robot. Compared with the fitting results of the laser tracker software, the fitted center of the intersecting circle has higher accuracy. The axis vectors of the first and the second axes are used, the axis vector of the first axis and the projection of the axis vector of the second axis on the vertical plane of the first axis are respectively used as the direction vector of the robot base coordinate system, and the conversion matrix of the measurement point from the measurement system to the robot system is constructed. By comparing the measurement point difference after conversion of the two conversion matrices, the conversion matrix using the second axis directly as the base coordinate system direction vector has a large measurement point conversion error.

The mining sequence affects the safe and efficient production of mines and the development and economic benefits of mining enterprises.In order to solve the problem of mining sequence during the fault-subsiding area of Heidaigou open-pit mine, three mining methods are proposed based on the coal and rock occurrence conditions, mine production status and equipment types.The evaluation indicators related to the program from the aspects of economy, technology and safety and used the three-dimensional modeling and simulated mining technology, qualitative and quantitative combination to determine the values of each parameter.Finally, The AHP-ideal point method was used to establish a comprehensive evaluation index system model to determine the optimal mining plan.

To improve blast casting effect, it is of great significance to reveal the mechanism of rock breaking and casting in higher bench with deep holes. In rock blast casting with column charge, the process and mechanical characteristic of rock breaking and casting were analyzed. By adopting theory analysis and formula deduced, the mechanism of stress wave and blasting gas action on rock breaking and casting were revealed. The results show that stress wave acts on hole wall and forms radial cracks and circumferential cracks, then blasting gas causes the crack to expand and form a broken block, and the remaining explosive gas energy causes the crushed rock block to throw along the direction of the minimum resistance line. [ABSTRACT FROM AUTHOR]

The static behavior of multiplanar overlapped CHS KK-joints both in plane and out of plane (multiplanar KK-Ov joint), with the background of steel roof engineering of the Shanghai Qizhong Tennis Center, was investigated by test under monotonic loading and nonlinear finite element analysis. The test procedure was presented in the paper, and loading capacity, failure mode, load-displacement curve and plastic deformation of the experimental joint were further explored. Based on the test study, nonlinear finite element modeling was developed and used in numerical simulation of the experimental joint. The calculating results agreed well with the experimental results. Test result and FE analysis indicate that the welded seams between the tension brace and chord are often cracked when the KK-Ov joint failed. Because of the configuration with four mutually overlapped braces, local deformation of chord wall of multiplanar KK-Ov joints is distinctly different from that of multiplanar gapped CHS KK-joints, and statistic results reveal that the main failure mode of KK-Ov joints is CLD3 + BLB, which means plastic failure and significant local deformation of the chord wall in the lap area occurring in the form of a radial fold and local buckling of the two compression braces. Multiplanar parameter ζ1 has some influence on the ultimate strength. The current standard formula used to calculate the bearing capacity of this KK-Ov joint test is conservative. [ABSTRACT FROM AUTHOR]

This paper reveals the deficiency of the formula for multiplanar overlapped CHS KK-joints both in plane and out of plane (multiplanar KK-Ov joint) in the existing specifications and documents, and carries out parametric analysis on multiplanar KK-Ov joints. The main influencing parameters of multiplanar-effects coefficient μKK were determined. By means of multiple nonlinear regression analysis, the function of multiplanar-effects coefficient μKK was proposed and validated. Then, an improved design formula for CHS KK-Ov joints was recommended and compared with the test and FEA data and with the formulae in existing design specifications. The conclusions can be drawn that the formula established by test database for multiplanar gapped CHS KK-joint is not suitable to predict the ultimate capacity of CHS KK-Ov joints with four mutually overlapped braces; the expression of the functional relation between μKK and it's main influence parameters γ (ratio of chord diameter to twice wall thickness), ζt (ratio of transverse gap length to diametor) can correctly reflect the effect of spatial geometric parameters on ultimate capacity; the formula proposed in the paper, which is more concise and practical, has a higher degree of accuracy and reliability to the design of multiplanar KK-Ov joints. [ABSTRACT FROM AUTHOR]