For mobile robot autonomous navigation, path planning algorithm matters. For the reason that traditional A* algorithm is unable to achieve the global path planning perfectly and avoid unknown obstacles at the same time, the mobile robot algorithm combining improved A* with adaptive DWA was proposed for path planning. Firstly, safe distance judgment is added in A* algorithm to avoid the problem that the path crosses the vertex of obstacle diagonally. Secondly, the dynamic tangential method is used to smooth the path of A* algorithm, which is more consistent with the actual motion curve of mobile robot. Then, the path key points explored by improved A* algorithm are extracted as intermediate target points of the velocity adaptive DWA algorithm. Unknown obstacles avoidance based on the optimal global path planning is realized. Finally, the proposed fusion algorithm’s feasibility is verified through mobile robot ROS simulation.

An insignificant number of studies have focused on employing penetration using mini-linear shaped charge jets for directionally controlled splitting of massive rocks. In this study, we adopt a numerical calculation method to simulate the penetration and formation of the main splitting surface of a concrete specimen, considering a wedge angle of 45° in both processes. The surface on the principal axial plane is found to split first due to linear jet penetration. In the case of single primary-plane splitting, cracks appear at both ends of the long axis of the penetration crack and the splitting surface extends diagonally from the center of the penetration. A transverse crack separates the splitting surface and the radial-fracture surface, and the degree of fracture decreases along the direction of the height of the specimen. Finally, a realistic physical model demonstrating penetration using a mini-linearshaped charge jet is established. It is a rapid and safe blasting technology to handle hazardous massive rocks during emergency rescuing or mining.

Based on a similar theory, a concrete model experiment and field experiment were designed to solve the problem of non-drilling breakage of large rock in blasting engineering. On this basis, smoothed particle hydrodynamics was utilized to calculate the most ideal bursting height. The results show that stress concentration effects at the ends of the axis are led by linear jet penetration, and the crack area shape is elongated. Furthermore, the expanding direction of the splitting crack is controlled. When the wedge vertex angle is 90°, the fragmentation the specimens is determined. When the wedge vertex angle is 60°, symmetrically radial fracture in center of the specimens is observed. When the wedge vertex angle is 45°, the single splitting surface along the axial direction of penetration on specimens is shown. The intensity of stress concentration of the principal axial plane can be increased by both the decrease of wedge vertex angle and the increase in length of the linear charge. Moreover, the numbers of fragments can be reduced, and the size of fragments can be increased.