Tham khảo tài liệu 'multi-robot systems from swarms to intelligent automata - parker et al (eds) part 8', kỹ thuật - công nghệ, cơ khí - chế tạo máy phục vụ nhu cầu học tập, nghiên cứu và làm việc hiệu quả | Merging Partial Maps without Using Odometry 141 Table 2. Results of scan matching trials using different heuristics Successes Failures All transformations 13 18 Consecutive segments 21 10 Random segments 10 21 Histogram 9 29 22 71 erence a drastic change of the field of view eliminates any common reference between scans thus automatic matching is impossible. Map Merging Experiments We considered the sequence composed of 29 scans S1 S2 . S29 Table 3 . The integration of this sequence of partial maps has been done off-line to test and compare the three methods. In all the three methods problems arose when integrating the sub-sequence from S25 to S27 which represents the hall Fig. 4 . Here due to a drastic rotation about 100 degrees of the robot in such an open and large environment the partial maps have only one or two segments in common. In order to close the loop and complete the experiments these partial maps were manually integrated together in all the three methods. Table 3. Experimental sequence of partial maps the segment lengths are in mm Environment Partial maps Avg of segments Avg length of segments Laboratory S1 S7 S28 S29 Hallway S8 S22 Hall S23 S27 607 Total S1 S29 Fig. 5 shows the final map composed of 278 segments obtained with the sequential method. The sequential method could not integrate all the partial maps in order to close the loop the method suddenly failed when we tried to integrate S21 which has only a few short segments in common with the rest of the map. Fig. 6 shows the final map composed of 519 segments obtained with the tree method. We applied the standard tree method until level 3 of the tree then we applied the heuristic presented in Section 4 to speed up the process. As we went down in the tree the size of the maps grew larger and larger and the execution of MATCH slowed down. For example the integration of two partial maps composed of 108 and 103 segments at .
