这个小车前面有三个超声波测距传感器，除了特别小的障碍物，基本上可以实现自动避障。其实esp8266更适合遥控，同样的硬件有遥控版的代码在另一篇文章里。

这货长这样

esp8266 电机驱动板，接口对应node mcu esp8266接口的定义：

上代码：

// connections for drive Motors
int PWM_L = 5;      //GPIO5 ,D1
int PWM_R = 4;   //GPIO4   ,D2
int DIR_L = 0;      //GPIO0, D3
int DIR_R = 2;     //GPIO2, D4

//set utralsonic pin
#define TRIG_L 14  //D5, GPIO14
#define ECHO_L 12  //D6, GPIO12

#define TRIG_R 13  //D7, GPIO13
#define ECHO_R 15  //D8, GPIO15

#define TRIG_M 9 //SD2, GPIO9
#define ECHO_M 10 //SD3, GPIO10

int distance_l;
int distance_r;
int distance_m;

String command;          // String to store app command state.
int SPEED = 1020;        // 330 - 1023.
int speed_Coeff = 3 ;    //转弯系数

int left_count; //计数器，指令执行次数，防止无限循环。
int right_count;

int command_left_count = 0;  //用于控制遥控命令的左右转的幅度
int command_right_count = 0;

int is_forward = 1; //0 停止前进，1可以前进
int is_backward_step = 0; //往后退几步
int is_turn_right = 0;
int is_turn_left  = 0;

void setup() {
  Serial.begin(115200);    // set up Serial library at 115200 bps
  Serial.println();
  Serial.println("*WiFi Robot Remote Control Mode*");
  Serial.println("--------------------------------------");

  pinMode(ECHO_L, INPUT);                    //Set EchoPin as input, to receive measure result from US-025,US-026
  pinMode(TRIG_L, OUTPUT);

  pinMode(ECHO_R, INPUT);                    //Set EchoPin as input, to receive measure result from US-025,US-026
  pinMode(TRIG_R, OUTPUT);

  pinMode(ECHO_M, INPUT);
  pinMode(TRIG_M, OUTPUT);

  // Set all the motor control pins to outputs
  pinMode(PWM_L, OUTPUT);
  pinMode(PWM_R, OUTPUT);
  pinMode(DIR_L, OUTPUT);
  pinMode(DIR_R, OUTPUT);

  // Turn off motors - Initial state
  digitalWrite(DIR_L, LOW);
  digitalWrite(DIR_R, LOW);
  analogWrite(PWM_L, 0);
  analogWrite(PWM_R, 0);

}


void loop() {
  distance_l = get_left_distance();
  distance_r = get_right_distance();
  distance_m = get_mid_distance();

  if (  ( (distance_l >= 5608) || ( (distance_l > 0) && (distance_l < 250)) )   &&   ( (distance_m >= 5608) || ( (distance_m > 0) && (distance_m < 250)) )   &&   ( (distance_r >= 5608) || ( (distance_r > 0) && (distance_r < 250))  )  ) {
    //0, 0, 0 停止前进，倒退默认向右转
    Backward_step();
    if ( distance_r  > distance_l ) {
      TurnRight();
    }
    else {
      TurnLeft();
    }

  }


  else if (  ( (distance_m == 5609) || ( (distance_m > 0) && (distance_m < 250))   ||  (distance_m == 5608)  ) &&  ((distance_l < 5608) && (distance_l >= 250)) &&  ((distance_r < 5608) && (distance_r >= 250)) ) {
    //1, 0, 1中间有障碍， 后退并选择方向转一步
    Backward_step();
    if ( distance_r > distance_l  ) {
      TurnRight();
    }
    else {
      TurnLeft();
    }

  }

  else if ( (((distance_l > 0) && (distance_l < 250)) || (distance_l == 5609)   ||  (distance_l == 5608) )   &&   ( ((distance_m >= 250 ) && (distance_m < 5608))  )    &&    ((distance_r < 5608) &&  (distance_r >= 250)) ) {
    //0,1,1左边有障碍，直接往右转，然后前进
    Backward_step();
    TurnRight();

  }

  else if ( (((distance_l > 0) && (distance_l < 250)) || (distance_l == 5609)   ||  (distance_l == 5608) )   &&   ( ((distance_m > 0) && (distance_m < 250)) ||   (distance_m == 5609)  ||  (distance_m == 5608))    &&    ((distance_r < 5608) &&  (distance_r >= 250)) ) {
    //0,0,1左边和中间有障碍，后退并右转
    Backward_step();
    TurnRight();
  }

  else  if ( (((distance_r > 0) && (distance_r < 250)) || (distance_r == 5609)    ||  (distance_r == 5608) )   &&  ( ((distance_m >= 250 ) && (distance_m < 5608))  )   &&   ((distance_l < 5608) && (distance_l >= 250))) {
    //1,1,0 右边有障碍, 左转并前进
    Backward_step();
    TurnLeft();
  }

  else  if ( (((distance_r > 0) && (distance_r < 250)) || (distance_r >= 5608)  )   &&    ( ((distance_m > 0) && (distance_m < 250)) ||   (distance_m >= 5608) )    &&    ((distance_l < 5608) && (distance_l >= 250))  ) {
    //1, 0, 0右边和中间有障碍, 停下并左转
    Backward_step();
    TurnLeft();

  }

  else if (  ( (distance_l >= 5608) || ( (distance_l > 0) && (distance_l < 250)) )   &&   (  (distance_m > 250) && (distance_m < 5608) )   &&   ( (distance_r >= 5608) || ( (distance_r > 0) && (distance_r < 250))  )  ) {
    //0, 1, 0  继续前进
    Forward();
  }

  else if (   (  (distance_l > 250) && (distance_l < 5608) )    &&   (  (distance_m > 250) && (distance_m < 5608) )   &&   (  (distance_r > 250) && (distance_r < 5608) )  ) {
    //1, 1, 1 继续前进
    Forward();
  }
}



int get_mid_distance() {
  unsigned long Time_Echo_us = 0;
  unsigned long Len_mm  = 0;

  digitalWrite(TRIG_M, HIGH);              //begin to send a high pulse, then US-025/US-026 begin to measure the distance
  delayMicroseconds(20);                    //set this high pulse width as 20us (>10us)
  digitalWrite(TRIG_M, LOW);               //end this high pulse

  Time_Echo_us = pulseIn(ECHO_M, HIGH);               //calculate the pulse width at EchoPin,
  if ((Time_Echo_us < 60000) && (Time_Echo_us > 1))    //a valid pulse width should be between (1, 60000).
  {
    Len_mm = (Time_Echo_us * 34 / 100) / 2; //calculate the distance by pulse width, Len_mm = (Time_Echo_us * 0.34mm/us) / 2 (mm)
    Serial.print("Present M_Distance is: ");  //output result to Serial monitor
    //Serial.print(Len_mm, DEC);            //output result to Serial monitor
    Serial.print(Len_mm);
    Serial.println("mm");                 //output result to Serial monitor
    return Len_mm;
  }
  else {
    return 0;
  }
}

int get_left_distance() {
  unsigned long Time_Echo_us = 0;
  unsigned long Len_mm  = 0;

  digitalWrite(TRIG_L, HIGH);              //begin to send a high pulse, then US-025/US-026 begin to measure the distance
  delayMicroseconds(20);                    //set this high pulse width as 20us (>10us)
  digitalWrite(TRIG_L, LOW);               //end this high pulse

  Time_Echo_us = pulseIn(ECHO_L, HIGH);               //calculate the pulse width at EchoPin,
  if ((Time_Echo_us < 60000) && (Time_Echo_us > 1))    //a valid pulse width should be between (1, 60000).
  {
    Len_mm = (Time_Echo_us * 34 / 100) / 2; //calculate the distance by pulse width, Len_mm = (Time_Echo_us * 0.34mm/us) / 2 (mm)
    Serial.print("Present L_Distance is: ");  //output result to Serial monitor
    //Serial.print(Len_mm, DEC);            //output result to Serial monitor
    Serial.print(Len_mm);
    Serial.println("mm");                 //output result to Serial monitor
    return Len_mm;
  }
  else {
    return 0;
  }
}

int get_right_distance() {
  unsigned long Time_Echo_us = 0;
  unsigned long Len_mm  = 0;

  digitalWrite(TRIG_R, HIGH);              //begin to send a high pulse, then US-025/US-026 begin to measure the distance
  delayMicroseconds(20);                    //set this high pulse width as 20us (>10us)
  digitalWrite(TRIG_R, LOW);               //end this high pulse

  Time_Echo_us = pulseIn(ECHO_R, HIGH);               //calculate the pulse width at EchoPin,
  if ((Time_Echo_us < 60000) && (Time_Echo_us > 1))    //a valid pulse width should be between (1, 60000).
  {
    Len_mm = (Time_Echo_us * 34 / 100) / 2; //calculate the distance by pulse width, Len_mm = (Time_Echo_us * 0.34mm/us) / 2 (mm)
    Serial.print("Present R_Distance is: ");  //output result to Serial monitor
    //Serial.print(Len_mm, DEC);            //output result to Serial monitor
    Serial.print(Len_mm);
    Serial.println("mm");                 //output result to Serial monitor
    return Len_mm;
  }
  else {
    return 0;
  }
}


//void handle_404() {
//  server.send(404, "text/plain", "404: Not found"); // Send HTTP status 404 (Not Found) when there's no handler for the URI in the request
//}

// function to stop motors
void Stop() {
  digitalWrite(DIR_L, LOW);
  digitalWrite(DIR_R, LOW);
  analogWrite(PWM_L, 0);
  analogWrite(PWM_R, 0);
  delay(300);
}



// function to move forward
void Forward() {
  digitalWrite(DIR_L, HIGH);
  digitalWrite(DIR_R, HIGH);
  analogWrite(PWM_L, SPEED);
  analogWrite(PWM_R, SPEED);
}


// function to move backward
void Backward() {
  digitalWrite(DIR_L, LOW);
  digitalWrite(DIR_R, LOW);
  analogWrite(PWM_L, SPEED);
  analogWrite(PWM_R, SPEED);
}

void Backward_step() {
  //往后退n步，然后根据需要往左或往右转，然后再开启前进使能
  digitalWrite(DIR_L, LOW);
  digitalWrite(DIR_R, LOW);
  analogWrite(PWM_L, SPEED);
  analogWrite(PWM_R, SPEED);
  delay(300);
  analogWrite(PWM_L, 0);
  analogWrite(PWM_R, 0);
  delay(300);
  
}

// function to turn right
void TurnRight() {
  digitalWrite(DIR_L, HIGH);
  digitalWrite(DIR_R, LOW);
  analogWrite(PWM_L, SPEED);
  analogWrite(PWM_R, SPEED);
  delay(200);
    analogWrite(PWM_L, 0);
  analogWrite(PWM_R, 0);
  delay(300);
}


// function to turn left
void TurnLeft() {
  digitalWrite(DIR_L, LOW);
  digitalWrite(DIR_R, HIGH);
  analogWrite(PWM_L, SPEED);
  analogWrite(PWM_R, SPEED);
  delay(200);
    analogWrite(PWM_L, 0);
  analogWrite(PWM_R, 0);
  delay(300);
}