car tracking & ultrasonic

//#include <Servo.h>
int Left_motor_go = 8;      //左电机前进(IN1)
int Left_motor_back = 9;    //左电机后退(IN2)
int Right_motor_go = 10;    // 右电机前进(IN3)
int Right_motor_back = 11;  // 右电机后退(IN4)

int key = A2;   //定义按键 数字A2 接口
int beep = A3;  //定义蜂鸣器 数字A3 接口
int LED = 7;    //定义蜂鸣器 数字A3 接口


const int SensorRight = 3;  //右循迹红外传感器()
const int SensorLeft = 4;   //左循迹红外传感器()

const int SensorLeft2 = 5;  // 中间红外避障传感器()

int SL;  //左循迹红外传感器状态
int SR;  //右循迹红外传感器状态

int SL2;  //中间避障红外传感器状态

void setup() {
  //初始化电机驱动IO为输出方式
  pinMode(Left_motor_go, OUTPUT);     // PIN 8 (PWM)
  pinMode(Left_motor_back, OUTPUT);   // PIN 9 (PWM)
  pinMode(Right_motor_go, OUTPUT);    // PIN 10 (PWM)
  pinMode(Right_motor_back, OUTPUT);  // PIN 11 (PWM)

  pinMode(LED, OUTPUT);  // PIN 7 LED输出
  pinMode(key, INPUT);   //定义按键接口为输入接口
  pinMode(beep, OUTPUT);
  pinMode(SensorRight, INPUT);  //定义右循迹红外传感器为输入
  pinMode(SensorLeft, INPUT);   //定义左循迹红外传感器为输入
  pinMode(SensorLeft2, INPUT);  //定义左循迹红外传感器为输入
  Serial.begin(9600);           // 初始化串口
}

//=======================智能小车的基本动作=========================
//void run(int time)     // 前进
void run() {
  digitalWrite(Right_motor_go, HIGH);  // 右电机前进
  digitalWrite(Right_motor_back, LOW);
  analogWrite(Right_motor_go, 140);  //PWM比例0~255调速，左右轮差异略增减
  analogWrite(Right_motor_back, 0);
  digitalWrite(Left_motor_go, LOW);  // 左电机前进
  digitalWrite(Left_motor_back, HIGH);
  analogWrite(Left_motor_go, 0);  //PWM比例0~255调速，左右轮差异略增减
  analogWrite(Left_motor_back, 140);
  //delay(time * 100);   //执行时间，可以调整
}

//void brake(int time)  //刹车，停车
void brake() {
  digitalWrite(Right_motor_go, LOW);
  digitalWrite(Right_motor_back, LOW);
  digitalWrite(Left_motor_go, LOW);
  digitalWrite(Left_motor_back, LOW);
  //delay(time * 100);//执行时间，可以调整
}

//void left(int time)         //左转(左轮不动，右轮前进)
void left() {
  digitalWrite(Right_motor_go, HIGH);  // 右电机前进
  digitalWrite(Right_motor_back, LOW);
  analogWrite(Right_motor_go, 140);
  analogWrite(Right_motor_back, 0);  //PWM比例0~255调速
  digitalWrite(Left_motor_go, LOW);  //左轮后退
  digitalWrite(Left_motor_back, LOW);
  analogWrite(Left_motor_go, 0);
  analogWrite(Left_motor_back, 0);  //PWM比例0~255调速
  //delay(time * 100);	//执行时间，可以调整
}

void spin_left()  //左转(左轮后退，右轮前进)
{
  digitalWrite(Right_motor_go, HIGH);  // 右电机前进
  digitalWrite(Right_motor_back, LOW);
  analogWrite(Right_motor_go, 140);
  analogWrite(Right_motor_back, 0);   //PWM比例0~255调速
  digitalWrite(Left_motor_go, HIGH);  //左轮后退
  digitalWrite(Left_motor_back, LOW);
  analogWrite(Left_motor_go, 100);
  analogWrite(Left_motor_back, 0);  //PWM比例0~255调速
                                    // delay(time * 100);	//执行时间，可以调整
}

//void right(int time)        //右转(右轮不动，左轮前进)
void right() {
  digitalWrite(Right_motor_go, LOW);  //右电机后退
  digitalWrite(Right_motor_back, LOW);
  analogWrite(Right_motor_go, 0);
  analogWrite(Right_motor_back, 0);  //PWM比例0~255调速
  digitalWrite(Left_motor_go, LOW);  //左电机前进
  digitalWrite(Left_motor_back, HIGH);
  analogWrite(Left_motor_go, 0);
  analogWrite(Left_motor_back, 140);  //PWM比例0~255调速
  //delay(time * 100);	//执行时间，可以调整
}

void spin_right()  //右转(右轮后退，左轮前进)
{
  digitalWrite(Right_motor_go, LOW);  //右电机后退
  digitalWrite(Right_motor_back, HIGH);
  analogWrite(Right_motor_go, 0);
  analogWrite(Right_motor_back, 100);  //PWM比例0~255调速
  digitalWrite(Left_motor_go, LOW);    //左电机前进
  digitalWrite(Left_motor_back, HIGH);
  analogWrite(Left_motor_go, 0);
  analogWrite(Left_motor_back, 140);  //PWM比例0~255调速
                                      //delay(time * 100);	//执行时间，可以调整
}

//void back(int time)          //后退
void back(int time) {
  digitalWrite(Right_motor_go, LOW);  //右电机后退
  digitalWrite(Right_motor_back, HIGH);
  analogWrite(Right_motor_go, 0);
  analogWrite(Right_motor_back, 200);  //PWM比例0~255调速
  digitalWrite(Left_motor_go, LOW);    //左电机前进
  digitalWrite(Left_motor_back, HIGH);
  analogWrite(Left_motor_go, 0);
  analogWrite(Left_motor_back, 200);  //PWM比例0~255调速
  //delay(time * 100);	//执行时间，可以调整
}
//==========================================================

void keysacn()  //按键扫描
{
  int val;
  val = digitalRead(key);    //读取数字7 口电平值赋给val
  while (!digitalRead(key))  //当按键没被按下时，一直循环
  {
    val = digitalRead(key);  //此句可省略，可让循环跑空
  }
  while (digitalRead(key))  //当按键被按下时
  {
    delay(10);               //延时10ms
    val = digitalRead(key);  //读取数字7 口电平值赋给val
    if (val == HIGH)         //第二次判断按键是否被按下
    {
      digitalWrite(beep, HIGH);   //蜂鸣器响
      while (!digitalRead(key))   //判断按键是否被松开
        digitalWrite(beep, LOW);  //蜂鸣器停止
    } else
      digitalWrite(beep, LOW);  //蜂鸣器停止
  }
}

void loop() {
  keysacn();  //调用按键扫描函数
  while (1) {
    //有信号为LOW  没有信号为HIGH
    SR = digitalRead(SensorRight);  //有信号表明在白色区域，车子底板上L3亮；没信号表明压在黑线上，车子底板上L3灭
    SL = digitalRead(SensorLeft);   //有信号表明在白色区域，车子底板上L2亮；没信号表明压在黑线上，车子底板上L2灭

    SL2 = digitalRead(SensorLeft2);

    if (SL2 == LOW)  //如果中间的避障传感器检测到障碍物
    {
      brake();  //停车
      digitalWrite(beep, HIGH);
      digitalWrite(LED, HIGH);
    } else {
      digitalWrite(beep, LOW);
      digitalWrite(LED, LOW);
      if (SL == LOW && SR == LOW)
        run();                          //调用前进函数
      else if (SL == HIGH & SR == LOW)  // 左循迹红外传感器,检测到信号，车子向右偏离轨道，向左转
        //spin_left();
        left();
      else if (SR == HIGH & SL == LOW)  // 右循迹红外传感器,检测到信号，车子向左偏离轨道，向右转
        //spin_right();
        right();
      else  // 都是黑色, 停止
        brake();
    }
  }
}