Arduino Uno Autonomous Car

1#define trigPin 12
2#define echoPin 13
3
4int n; 
5int duration,  distance;
6
7String readString;
8
9#include <Servo.h> 
10Servo myservo1;  // create servo object to control servo 
11Servo myservo2;
12
13void setup()  {
14  Serial.begin(9600);
15  myservo1.attach(8); // assigns the servo to a pin
16  myservo2.attach(9);
17  pinMode(trigPin, OUTPUT);
18  pinMode(echoPin, INPUT);
19  pinMode(3, OUTPUT);
20}
21
22void loop() {
23  digitalWrite(trigPin, HIGH);
24  _delay_ms(500);
25  digitalWrite(trigPin, LOW);
26  duration = pulseIn(echoPin,  HIGH);
27  distance = (duration/2) / 29.1;
28        
29  if (distance < 40)  { // this is the distance which the rover has to stop
30    digitalWrite(3, HIGH);
31    myservo1.write(n); // controls the direction of the motors
32    myservo2.write(180-n);
33   delay(1000);  // how long the wheels spin
34   myservo1.write(n);
35   myservo2.write(90-n);
36   delay(500);
37}
38  else { // what the rover will do if it doen't sense anything
39    digitalWrite(3, LOW);
40    myservo1.write(180-n);
41    myservo2.write(n);
42}
43}  
44
45