柱子P1、P2的位置是可以随意摆放的，机器人R沿黑线方向行走。利用6号和9号声纳来测距离（这两个声纳的测量角度比较大，可以很好号的实现设计要求），6号声纳测机器人与P1的距离d1，9号测机器人与P2的距离d2。当机器人行走到某处时，两个声纳分别测到的距离差d1-d2小于20mm，并且d1、d2都小于600mm时，则判断为此时机器人行走到了P1与P2的中间，机器人转90°，沿两柱子的中心线继续向前走。-Columns P1, P2 position can be arbitrarily placed, the direction of the robot R to walk along the black line. 6 and 9, using sonar to measure the distance (the measurement point of view the two sonar relatively large, a good number can meet the design requirements), 6 sonar distance measuring robot and P1 d1, 9 号 testing machine Man and P2 distance d2. When the robot to walk somewhere, two sonar distances were measured to the difference d1-d2 is less than 20mm, and d1, d2 is less than 600mm, then determine the robot to walk at this time to the middle of P1 and P2 the robot turn 90 °, along the center line of the two pillars to continue to move forward.