碰撞检测人群netlogo

Question

这就是我所拥有的。我需要乌龟从圈子形成和         移动到另一个地方，同时防止碰撞和进入         再次圈起来。

    ;;creates circle of people
    turtles-own [collides?]
    to setup
      clear-all

      setup-circle
      reset-ticks
    end
   to setup-circle
     create-ordered-turtles crowd-size [
       set shape "person" fd 10 rt 90]
   end
   to go
     ask turtles [
     fd .1 
     ]

     tick
   end