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182                                    Autonomous Mobile Robots

                                         0.03


                                        0.025

                                       Position error (m)  0.015
                                         0.02






                                         0.01



                                        0.005
                                            0.5  1   1.5  2   2.5  3   3.5  4   4.5  5   5.5
                                                               Range (m)
                                FIGURE 4.19 Plot showing the increase of position error with range to targets and line
                                of best fit.
                                          1.5

                                           1

                                          0.5

                                           0
                                        y (m)
                                         – 0.5
                                          – 1

                                         – 1.5

                                          – 2
                                           – 1.5  – 1  – 0.5   0    0.5    1     1.5    2
                                                                 x (m)

                                FIGURE 4.20  Localization along square path (solid line indicates true path taken and
                                circles are the geometric targets used for localization).


                                   A typical set of continuous localization results are displayed in Figure 4.20.
                                The robot was moved one loop around a 1.57 m square at 0.2 m/sec. The laser
                                                                                     ◦
                                scanner mounted on the robot has a maximum scan angle of 180 and so the
                                robothadtoreversealongsomeedgesofthesquareinordertomaintaintracking.




                                 © 2006 by Taylor & Francis Group, LLC



                                FRANKL: “dk6033_c004” — 2006/3/31 — 16:42 — page 182 — #34
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