tailieunhanh - Crc Press - Mechanical Engineering Handbook - Robotics 1 Part 8

Tham khảo tài liệu 'crc press - mechanical engineering handbook - robotics 1 part 8', kỹ thuật - công nghệ, cơ khí - chế tạo máy phục vụ nhu cầu học tập, nghiên cứu và làm việc hiệu quả | 14-70 Section 14 FIGURE Illustration of path-planning problem. The abstract model of the path-planning problem can take different forms depending on the application characteristics. It can be in two dimensions or in three dimensions. The concern can be the end effector alone or the entire robot arm. The end effector can be considered as a solid body or an infinitesimal point. Different considerations can have significant implications on the solution methodology and complexity. In this handbook we will only discuss the simplest cases in which a point end effector in two-dimensional space is concerned. The readers are referred to Latombe 1991 for more complex procedures. Road Map Approach Based on Visibility Graph The road map approach is one of the earliest path-planning methods. The obstacles are modeled as polygons. A visibility graph is a nondirected graph. The nodes of the graph are the vertices of the polygons the initial point and the goal point. The links of the graphs are straight-line segments that connect a pair of nodes without intersecting with any obstacles. A reduced visibility graph for the example is shown in Figure . A reduced visibility graph does not contain links that are dominated by other links in terms of distance. The elliptical obstacle is approximated by a hexagon. In the visibility graph all the paths consisting of successive links that connect Cinit to Cgoal represent semicollision-free paths. The coarse line represents one of these paths. The use of the term semicollision free is due to the fact the path may actually contact an obstacle. It is clear that the path is not unique. In the example the possible paths can be Cinit UCgoal Cinit BCgoal or Cinit CD goA. Some offer shorter travel distances while others offer smoother paths. This method can be extended to include circular end effector and obstacles which have lines and arcs as boundaries. Road Map Approach Based on Voronoi Diagram For the same problem described above .