使用距离变量 - 机器人割草机仿真项目

Question

我正在尝试在 Netlogo 上模拟机器人割草机 (like this one)。我希望它能在电量不足时找到回家的路给自己充电。

但是我找不到有效的解决方案，因为我收到错误“DISTANCE expected 输入成为代理人却得到了 NOBODY。”每次。

我刚开始学习 Netlogo，如果有人能帮助我找到解决方案，我会很高兴。

Interface

谢谢！

breed [cars car]
cars-own [target]

breed [houses house]

to setup
  clear-all
  setup-patches
  setup-cars
  setup-house
  reset-ticks
end


to setup-patches
  ask patches [set pcolor green] ;;Setup grass patches
  ask patches with [ pycor >= -16  and pycor >= 16] 
  [ set pcolor red ] ;; setup a red frame stopping the lawn mower
    ask patches with [ pycor <= -16  and pycor <= 16]
  [ set pcolor red ]
    ask patches with [ pxcor >= -16  and pxcor >= 16]
  [ set pcolor red ]
    ask patches with [ pxcor <= -16  and pxcor <= 16]
  [ set pcolor red ]
end

to setup-cars
create-cars 1 [
    setxy 8 8
    set target one-of houses
  ]

end

to setup-house
  set-default-shape houses "house"
  ask patch 7 8 [sprout-houses 1]
end

to place-walls ;; to choose obstacles with mouse clicks
  if mouse-down? [
    ask patch mouse-xcor mouse-ycor [ set pcolor red ]
    display
  ]
end


to go
  move-cars
  cut-grass
  check-death ;; Vérify % battery.
  tick
end

to move-cars
  ask cars
  [
    ifelse [pcolor] of patch-ahead 1 = red
      [ lt random-float 360 ]   ;; cant go on red as it is a wall
      [ fd 1 ]                  ;; otherwise go
    set energy energy - 1
]
  tick
end

to cut-grass
  ask cars [
    if pcolor = green [
      set pcolor gray
    ]
  ]
end

to check-death ;; check battery level
  ask cars [
    ifelse energy >= 150
    [set label "energy ok"]
    [if distance target = 0
      [ set target one-of houses
        face target ]
    ;; move towards target.  once the distance is less than 1,
    ;; use move-to to land exactly on the target.
    ifelse distance target < 1
      [ move-to target ]
      [ fd 1 ]
   ]
  ]
end

Answer 1

看起来问题是由于您 setup-cars 在 setup-houses 之前 - 因此没有 house 新 car 设置为它目标。您可以更改设置调用的顺序，或者可以将 if distance target = 0 更改为 if target = nobody，或者您可以执行以下操作，当能量下降时，海龟将只选择最近的房子作为目标低于 0:

to check-death
  ask cars [
    ifelse energy >= 150 
    [ set label "Energy ok" ]
    [ set target min-one-of houses [distance myself]
      face target 
      ifelse distance target < 1
      [ move-to target ]
      [ fd 1 ]
    ]
  ]
end

附带说明一下，如果您计划扩展模型以包含更多割草机，您可能希望将 energy 设置为海龟变量。如果你打算让世界变得更大，你可能还想稍微改变你的框架设置来动态缩放——比如：

to setup-patches
  ask patches [set pcolor green] ;;Setup grass patches
  ask patches with [ 
    pxcor = max-pxcor or
    pxcor = min-pxcor or
    pycor = max-pycor or
    pycor = min-pycor ] [
    set pcolor red 
  ]
end

使用距离变量 - 机器人割草机仿真项目

Using the distance variable - Robotic lawn mower simulation project

netlogo