一、实验准备

        通过四路巡线模块与小车结合，实现小车巡黑线。

1. 小车接线已安装
2. 调试四路巡迹模块。调节四路循迹模块旋钮，调节成遇黑线时，指示灯亮；不是黑线时，指示灯灭。

二、实验原理

        检测不同形状的赛道时，四路巡线传感器的状态，如下图所示。根据传感器状态来控制小车进行不同的运动。

三、实验源码

import sys
sys.path.append('/home/pi/project_demo/lib')
#导入麦克纳姆小车驱动库 Import Mecanum Car Driver Library
from McLumk_Wheel_Sports import *
​
speed =30#30
try:
    while True:
        # 从I2C读取巡线传感器数据 Read line sensor data from I2C
        track_data = bot.read_data_array(0x0a, 1)
        track = int(track_data[0])
​
        # 解析巡线传感器的状态 Analyze the status of the line patrol sensor
        x1 = (track >> 3) & 0x01  
        x2 = (track >> 2) & 0x01  
        x3 = (track >> 1) & 0x01  
        x4 = track & 0x01       
        """
        X2 X1 X3 X4
        |  |  |  |
        L1 L2 R1 R2
        """
        lineL1=x2
        lineL2=x1
        lineR1=x3
        lineR2=x4
​
        if lineL1 == 0 and lineL2 == 0 and lineR1 == 0 and lineR2 == 0:  # 都是黑色, 加速前进 All black, speed up
            print("1")
            print(lineL1,lineL2,lineR1,lineR2)
            move_forward(int(speed))
        elif( (lineL2 == 0 or lineL1 == 0) and lineR2 == 0):#右锐角：右大弯,0表示检测到黑线 Right acute angle: right big bend, 0 means black line is detected
            print("2")
            print(lineL1,lineL2,lineR1,lineR2)
            rotate_right(speed)
            time.sleep(0.05)
        elif lineL1 == 0 and (lineR2 == 0 or lineR1 == 0):  # 左锐角或左大弯 Left sharp angle or left sharp bend
            print("3")
            print(lineL1,lineL2,lineR1,lineR2) 
            rotate_left(int(speed*1.5))  # 左急转弯 Sharp left turn
            time.sleep(0.15)
        elif lineL1 == 0:  # 左最外侧检测 Left outermost detection
            print("4")
            print(lineL1,lineL2,lineR1,lineR2)
            rotate_left(speed)  # 左急转弯 Sharp left turn
            time.sleep(0.02)
        elif lineR2 == 0:  # 右最外侧检测 Right outermost detection
            print("5")
            print(lineL1,lineL2,lineR1,lineR2)
            rotate_right(speed)
            time.sleep(0.01)
        elif lineL2 == 0 and lineR1 == 1:  # 中间黑线上的传感器微调车左转 The sensor on the middle black line fine-tunes the car to turn left
            print("6")
            print(lineL1,lineL2,lineR1,lineR2)
            rotate_left(int(speed))  # 左转 Turn left
        elif lineL2 == 1 and lineR1 == 0:  # 中间黑线上的传感器微调车右转 The sensor on the middle black line fine-tunes the car to turn right
            print("7")
            print(lineL1,lineL2,lineR1,lineR2) 
            rotate_right(int(speed)) #右转 Turn right
        elif lineL2 == 0 and lineR1 == 0:  # 都是黑色, 加速前进 All black, speed up
            print("8")
            print(lineL1,lineL2,lineR1,lineR2)
            move_forward(speed)
​
        # 等待一段时间再进行下一次检测 Wait for a while before the next test
        time.sleep(0.01)
​
except KeyboardInterrupt:
    # 当用户中断程序时，确保所有电机停止 Ensure that all motors stop when the user interrupts the program
    stop()
    print("Ending")

四、实验现象

        我们把小车放在巡线赛道上，确认已经调节了模块旋钮，调成遇黑线时，指示灯亮后，运行代码块，小车会巡黑线行驶。