Obstacle Avoiding Robot

1int L1 = 6;
2int L2 = 7;
3int R1 = 5;
4int R2 = 4;
5
6
7int  trigPin= 2;    
8int echoPin= 3;   
9long duration, dist, average;   
10long  aver[3];   //array for averagh(servoPin);  
11
12void setup() 
13{
14  pinMode(L1,  OUTPUT);// see the program here
15  pinMode(L2, OUTPUT);// it works welll
16  pinMode(R1,  OUTPUT);// did u make this code
17  pinMode(R2, OUTPUT); // put your setup code  here, to run once:
18
19digitalWrite(L1, LOW);
20 digitalWrite(L2, LOW);
21  digitalWrite(R1, LOW);
22 digitalWrite(R2, LOW);
23
24   pinMode(trigPin, OUTPUT);
25    pinMode(echoPin, INPUT);
26
27Serial.begin(9600);
28Serial.write("Arduino  has successfully started");
29
30}
31
32void front(){
33  digitalWrite(L1,  HIGH);
34  digitalWrite(L2, LOW);
35  digitalWrite(R1, LOW);
36  digitalWrite(R2,  HIGH);  
37}
38
39void back(){
40  digitalWrite(L1, LOW);
41  digitalWrite(L2,  HIGH);
42  digitalWrite(R1, HIGH);
43  digitalWrite(R2, LOW);  
44}
45
46
47void  right(){
48  digitalWrite(L1, HIGH);
49  digitalWrite(L2, LOW);
50  digitalWrite(R1,  HIGH);
51  digitalWrite(R2, LOW);    
52}
53void measure() {  
54 digitalWrite(10,HIGH);
55digitalWrite(trigPin,  LOW);
56delayMicroseconds(5);
57digitalWrite(trigPin, HIGH);
58delayMicroseconds(15);
59digitalWrite(trigPin,  LOW);
60pinMode(echoPin, INPUT);
61duration = pulseIn(echoPin, HIGH);
62dist  = (duration/2) / 29.1;    //obtain distance
63}
64
65
66void loop() {
67
68
69  for (int i=0;i<=2;i++) {   //average distance
70    measure();               
71   aver[i]=dist;            
72    delay(10);              //delay between measurements
73  }
74 dist=(aver[0]+aver[1]+aver[2])/3;    
75
76
77Serial.print(dist);
78
79
80
81if  (dist <  20 ){
82  
83  front();
84}
85
86if (dist > 20){
87  
88  right();
89}
90if  ( dist >
91  
92}
93