c - 如何让我的机器人沿着黑色胶带沿着矩形路径移动？

Question

我正在研究一个机器人，它是我们学院夏季机器人研讨会的一部分。我们正在使用 A-WIT 的 C-STAMP 微 Controller 。我能够让它移动，左转，右转，向后移动。我什至设法使用对比传感器让它沿着黑色胶带移动。

我让机器人以 30-45 度角朝向 table 上的黑色胶带，它自行对齐并开始沿着黑色胶带移动。它有点抽搐，可能是由于我下面的编程逻辑，它正在运行一个 while 循环并不断检查 if 语句，所以它最终会每隔几毫秒尝试左右转动一次，这就解释了抽搐的部分。但是没关系，它可以工作，虽然没有我想要的那么流畅但是它可以工作!问题是我不能让我的机器人进入黑色胶带的矩形路径。一旦到达黑色胶带的拐角，它就会继续直行，而不是左转或右转。

我的 2 个传感器位于机器人正下方，靠近前轮，几乎与地板齐平。它具有从 0 到 8 的“索引”值。八是最亮的对比度，零是最暗的对比度。因此，当机器人进入黑带区域时，索引值下降，基于此，我有一个 if 语句告诉我的机器人向左转或向右转。

这是我的尝试。为避免混淆，我没有发布完整的源代码，而只发布了负责我的机器人沿着黑色胶带移动的逻辑部分。

while(1) {

    // don't worry about these.
    // 10 and 9 represent Sensor's PIN location on the motherboard
    V = ANALOGIN(10, 1, 0, 0, 0);
    V2 = ANALOGIN(9, 1, 0, 0, 0);

    // i got this "formula" from the example in my Manual. 
    // V stands for voltage of the sensor.
    // it gives me the index value of the sensor. 0 = darkest, 8 = lightest.
    index = ((-(V - 5) / 5) * 8 + 0.5);
    index2 = ((-(V2 - 5) / 5) * 8 + 0.5);

    // i've tweaked the position of the sensors so index > 7 is just right number.
    // the robot will move anywhere on the table just fine with index > 7. 
    // as soon as it drops to or below 7 (i.e. finds black tape), the robot will 
    // either turn left or right and then go forward.

    // lp & rp represent left-wheel pin and right-wheel pin, 1 means run forever.
    // if i change it from 1 to 100, it will go forward for 100ms.
    if (index > 7 && index2 > 7)
        goForward(lp, rp, 1);

    if (index <= 7) {
        turnLeft(lp, rp, 1);
        goForward(lp, rp, 1);
        // this is the tricky part. i've added this code last minute
            // trying to make my robot turn, but i didn't work.
        if (index > 4) {
            turnLeft(lp, rp, 1);
            goForward(lp, rp, 1);
        }
    }

    else if (index2 <= 7) {
        turnRight(lp, rp, 1);
        goForward(lp, rp, 1);
            // this is also the last minute addition. it's same code as above
            // but it's for the 2nd sensor.
        if (index2 > 4) {
            turnRight(lp, rp, 1);
            goForward(lp, rp, 1);
        }
    }
}

我花了一整天的时间试图弄明白。我几乎用尽了所有途径。在 stackoverflow 上寻求解决方案是我现在最后的选择。

提前致谢!如果您对代码有任何疑问，请告诉我，但注释应该是不言自明的。

这是我的 goForward 函数，以防有人疑惑:

void goForward(BYTE lp, BYTE rp, WORD t)
{
    WORD i;

    for(i = 0; i < t; i = i + 1){
        PULSOUT(lp, 400, 1, 1);
        PULSOUT(rp, 800, 1, 1);
        PAUSE(17);
    }
}

更新:这是我到目前为止的想法。我删除了之前发布的所有 if 语句，并决定从头开始编写逻辑:

// if there's enough bright light in both sensors at the same time
    // robot will move forward forever.
    if (index > 7 && index2 > 7)
        goForward(lp, rp, 1);

    // but if there's not enough bright light anymore (i.e. reached black tape)
    // proceed to the else-statement.
    else {
        // if left sensor detects the black tape then turn right
        // if doesn't detect the black tape then keep going forward
        if (index2 <= 7)
            turnRight(lp, rp, 1);
        else
            goForward(lp, rp, 1);

        // if right sensor detects the black tape then turn left
        // if it doesn't detect the black tape then keep going forward
        if (index <= 7) 
            turnLeft(lp, rp, 1);
        else 
            goForward(lp, rp, 1);
    }

    // The reason for turnLeft and turnRight is to keep robot re-alligning
    // to the black tape. It will happen so fast (every 1ms) that the jerking
    // shouldn't even be noticeable.

Answer 1

你需要捕捉突然出现的情况:[cycle n]“我看到磁带”-> [cycle n+1]“我没有看到磁带”当你遇到一个角落时发生。

A state machine是处理此类问题的好方法。用state machine特定状态的代码是隔离的，它仅在状态为真时运行。这种隔离可防止“串扰”并为每个状态提供一个已知代码块。

给定您的示例，流程可能类似于:

:Loop

State == Moving forward and on tape.
  read sensors
  delta = abs(valueLastCycle - valueThisCycle);
  if (delta >= bigChangeValue){
    // the tape was just gone. 
    // change state and handle this situation.
    CurrentState = suddenValueChange;
  }else
    if (index <= 7) {
        turnLeft(lp, rp, 1);
        goForward(lp, rp, 1);
    else if (index2 <= 7) {
        turnRight(lp, rp, 1);
        goForward(lp, rp, 1);
    }
   ...
State == suddenValueChange
 ...
 code that handles sudden value change event
 maybe:
 Stop Robot;
 Move backwards slowly until on tape or distance x
 etc...

Goto Loop

提高扫描速度似乎有帮助……但机器人移动得越快，您的扫描速度就越快……即您可能仍会从磁带上跳转 -> 磁带外，在这种情况下，您当前的代码会出现问题。