树莓派小车循迹代码pid

下面是一个基于PID算法的树莓派小车循迹代码示例：

import RPi.GPIO as GPIO
import time
 
# 设置GPIO引脚编号模式
GPIO.setmode(GPIO.BOARD)
 
# 定义引脚
left_pin = 11
middle_pin = 13
right_pin = 15
ENA = 33
ENB = 35
in1 = 31
in2 = 29
in3 = 36
in4 = 38
 
# 设置引脚的输入/输出状态
GPIO.setup(left_pin, GPIO.IN)
GPIO.setup(middle_pin, GPIO.IN)
GPIO.setup(right_pin, GPIO.IN)
GPIO.setup(ENA, GPIO.OUT)
GPIO.setup(ENB, GPIO.OUT)
GPIO.setup(in1, GPIO.OUT)
GPIO.setup(in2, GPIO.OUT)
GPIO.setup(in3, GPIO.OUT)
GPIO.setup(in4, GPIO.OUT)
 
# 设置PWM频率和占空比
pwm_a = GPIO.PWM(ENA, 500)
pwm_b = GPIO.PWM(ENB, 500)
pwm_a.start(0)
pwm_b.start(0)
 
# 定义PID参数
Kp = 0.5
Ki = 0.01
Kd = 0.1
 
# 定义PID误差变量
last_error = 0
integral = 0
 
# 定义小车运动控制函数
def car_move(speed, direction):
    if direction == 'left':
        GPIO.output(in1, GPIO.HIGH)
        GPIO.output(in2, GPIO.LOW)
        GPIO.output(in3, GPIO.HIGH)
        GPIO.output(in4, GPIO.LOW)
    elif direction == 'right':
        GPIO.output(in1, GPIO.LOW)
        GPIO.output(in2, GPIO.HIGH)
        GPIO.output(in3, GPIO.LOW)
        GPIO.output(in4, GPIO.HIGH)
    else:
        GPIO.output(in1, GPIO.HIGH)
        GPIO.output(in2, GPIO.LOW)
        GPIO.output(in3, GPIO.LOW)
        GPIO.output(in4, GPIO.HIGH)
    pwm_a.ChangeDutyCycle(speed)
    pwm_b.ChangeDutyCycle(speed)
 
# 定义PID函数
def pid_control():
    global last_error, integral
    left = GPIO.input(left_pin)
    middle = GPIO.input(middle_pin)
    right = GPIO.input(right_pin)
    error = 0
    if middle == 0:
        error = 0
    elif left == 0:
        error = -1
    elif right == 0:
        error = 1
    else:
        error = 0
    derivative = error - last_error
    last_error = error
    integral = integral + error
    output = Kp * error + Ki * integral + Kd * derivative
    return output
 
# 循迹控制主函数
def main():
    while True:
        output = pid_control()
        if output > 0:
            car_move(output, 'left')
        elif output < 0:
            car_move(-output, 'right')
        else:
            car_move(50, 'straight')
        time.sleep(0.01)
 
# 运行主函数
try:
    main()
except KeyboardInterrupt:
    pass
 
# 停止PWM信号输出
pwm_a.stop()
pwm_b.stop()
 
# 清空GPIO引脚状态
GPIO.cleanup()

该代码使用了GPIO库来对树莓派的引脚进行控制，使用了PWM信号来控制小车的速度和方向。PID算法用于根据循迹传感器的数据来计算小车的运动方向。代码中的Kp、Ki和Kd是PID控制器的参数，可以根据实际情况进行调整。