Example Code for Arduino-Obstacle Avoidance

Hardware Preparation

• 4WD Mobile Platform (Arduino Controller Supported), ROB0003, 1, DFRobot
• Romeo-All in one Controller, DFR0225, 1, Romeo
• DF05BB Standard Servo (5kg), SER0020, 1, DFRobot
• IR Kit For Arduino, DFR0107, 1, DFRobot
• 10 sets M3 * 10 hexagonal standoffs mounting kit, FIT0063, 1, DFRobot
• URM ultrasound mounting bracket, FIT0006, 1, DFRobot
• URM37 V4.0 Ultrasonic Sensor, SEN0001, 1, DFRobot
• Adjustable Infrared Sensor Switch, SEN0019, 3, DFRobot
• Light Disc with 7 SMD RGB LED, DFR0106, 2, DFRobot
• DFRobot Bluetooth V3, TEL0026, 1, DFRobot
• Pan and Tilt Kit (Black Anodized) (no servos), FIT0004, 1, DFRobot
• Wire cutter and wire stripper, 1, -
• Soldering Iron, 1, -
• Solder, 1, -
• Phillips Screw Driver, 1, -
• Pliers, 1, -
• 5xAA batteries (1.2V rechargeable or 1.5V alkaline), 1 set, -

Software Preparation

• Arduino IDE (download from Arduino)

Wiring Diagram

Connect the IR sensors to analog pins 2, 3, and 4:

Other wiring matches the Bluetooth Remote Control section.

Other Preparation Work

1. Ensure the IR sensors are mounted correctly on the robot.
2. Test the IR sensors to confirm they detect obstacles (output LOW when obstacles are near).
3. Power the robot with 5xAA batteries.

Sample Code

int E1 = 5;     //M1 Speed Control
int E2 = 6;     //M2 Speed Control
int M1 = 4;    //M1 Direction Control
int M2 = 7;    //M1 Direction Control

void stop(void)                    //Stop
{
  digitalWrite(E1,LOW);
  digitalWrite(E2,LOW);
}
void advance(char a,char b)          //Move forward
{
  analogWrite (E1,a);      //PWM Speed Control
  digitalWrite(M1,HIGH);
  analogWrite (E2,b);
  digitalWrite(M2,HIGH);
}
void back_off (char a,char b)          //Move backward
{
  analogWrite (E1,a);
  digitalWrite(M1,LOW);
  analogWrite (E2,b);
  digitalWrite(M2,LOW);
}
void turn_L (char a,char b)             //Turn Left
{
  analogWrite (E1,a);
  digitalWrite(M1,LOW);
  analogWrite (E2,b);
  digitalWrite(M2,HIGH);
}
void turn_R (char a,char b)             //Turn Right
{
  analogWrite (E1,a);
  digitalWrite(M1,HIGH);
  analogWrite (E2,b);
  digitalWrite(M2,LOW);
}


void setup()
{
  Serial.begin(9600);
  pinMode( A2 , INPUT);
  pinMode( A3 , INPUT);
  pinMode( A4 , INPUT);
  int i;
  for(i=6;i<=9;i++)
    pinMode(i, OUTPUT);

}

void loop()
{
  if (( !(  digitalRead( A2) ) || ( ( !(   digitalRead( A3) ) && ( !(   digitalRead(A2) ) && !(  digitalRead( A1) ) ) ) || ( !(  digitalRead( A3) ) && !(  digitalRead( A1) ) ) ) ))//read sensor from IR distence switch
  {
    back_off(240,240);
    delay(1000);
    Serial.print( "back" );

    Serial.println("");
    if (random( 1024 )>512)
    {
      turn_R(240,240);
      delay(1000);
      Serial.print( "random right" );
      Serial.println("");
    }
    else
    {
      turn_L(240,240);
      delay(1000);
      Serial.print( "random left" );
      Serial.println("");
    }


  }
  else
  {
    if (( !(  digitalRead( A3) ) || ( !(  digitalRead(  A2) ) && !(  digitalRead( A3) ) ) ))//read sensor from IR distence switch
    {
      back_off(240,240);
      delay(1000);
      turn_L(240,240);
      delay(1000);
      Serial.print( "back and  left" );
      Serial.println("");
    }
    else
    {
      if (( !(  digitalRead( A1) ) || ( !(  digitalRead( A1) ) && !(  digitalRead( A2) ) ) ))//read sensor from IR distence switch
      {
        back_off(240,240);
        delay(1000);
        turn_R(240,240);
        delay(1000);
        Serial.print( "back and right" );
        Serial.println("");
      }
      else
      {
        advance(240,240);
        delay(1000);

        Serial.print( "go" );
        Serial.println("");
      }
    }
  }
}

Result

• When obstacles are detected ahead, the robot backs up and turns randomly (left or right).
• When obstacles are detected on the left, the robot backs up and turns left.
• When obstacles are detected on the right, the robot backs up and turns right.
• When no obstacles are detected, the robot moves forward.

Additional Information

• The robot uses random(1024) to choose left/right turns for obstacle avoidance.
• Adjust the delay(1000) values to change the duration of backup/turning movements.