void loop() {
  // put your main code here, to run repeatedly:
  avoidance();
}
void motorRun(int cmd,int value)
{
  analogWrite(leftPWM, value);    // Set PWM output, set speed
  analogWrite(rightPWM, value);
  switch(cmd){
    case FORWARD:
      Serial.println("FORWARD");   // signal output
      digitalWrite(leftMotor1, HIGH);
      digitalWrite(leftMotor2, LOW);
      digitalWrite(rightMotor1, HIGH);
      digitalWrite(rightMotor2, LOW);
      break;
     case BACKWARD:
      Serial.println("BACKWARD"); // signal output
      digitalWrite(leftMotor1, LOW);
      digitalWrite(leftMotor2, HIGH);
      digitalWrite(rightMotor1, LOW);
      digitalWrite(rightMotor2, HIGH);
      break;
     case TURNLEFT:
      Serial.println("TURN  LEFT");     // signal output
      digitalWrite(leftMotor1, HIGH);
      digitalWrite(leftMotor2, LOW);
      digitalWrite(rightMotor1, LOW);
      digitalWrite(rightMotor2, HIGH);
      break;
     case TURNRIGHT:
      Serial.println("TURN  RIGHT");   // signal output
      digitalWrite(leftMotor1, LOW);
      digitalWrite(leftMotor2, HIGH);
      digitalWrite(rightMotor1, HIGH);
      digitalWrite(rightMotor2, LOW);
      break;
     default:
      Serial.println("STOP");     // signal output
      digitalWrite(leftMotor1, LOW);
      digitalWrite(leftMotor2, LOW);
      digitalWrite(rightMotor1, LOW);
      digitalWrite(rightMotor2, LOW);
  }
}
void avoidance()
{
  int pos;
  int dis[3];      // long
  motorRun(FORWARD,200);
  myServo.write(90);
  dis[1]=getDistance();    //middle
 
  if(dis[1]<30)
  {
    motorRun(STOP,0);
    for (pos = 90; pos <= 150; pos += 1)
    {
      myServo.write(pos);              // tell servo to go to position in variable 'pos'
      delay(15);                       // waits 15ms for the servo to reach the position
    }
    dis[2]=getDistance(); // left
    for (pos = 150; pos >= 30; pos -= 1)
    {
      myServo.write(pos);     // tell servo to go to position in variable 'pos'
      delay(15);              // waits 15ms for the servo to reach the position
      if(pos==90)
        dis[1]=getDistance();   // middle
    }
    dis[0]=getDistance();    // right
    for (pos = 30; pos <= 90; pos += 1)
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