How to Make Arduino Sumo Robot

1/*
2
3 by ahmed Azouz
4  https://www.instructables.com/id/How-to-Make-Ardu...
5
6  Download the lib from here first
7  https://github.com/ErickSimoes/Ultrasonic/blob/ma...
8
9*/
10#include  Ultrasonic.h
11
12Ultrasonic ultrasonic(4,3);
13
14const int IN1=5;
15const  int IN2=6;
16const int IN3=9;
17const int IN4=10;
18#define IR_sensor_front A0  // front sensor
19#define IR_sensor_back A1 // rear senson
20int distance ;
21
22void  setup() 
23{
24Serial.begin(9600);
25delay (5000); // as per sumo compat roles
26}
27void  loop()
28{
29  
30 int IR_front = analogRead(IR_sensor_front);
31 int IR_back  = analogRead(IR_sensor_back);
32 distance = ultrasonic.read();
33 ROTATE(200);  // start rotete if (distance < 20){
34    Stop();
35    while (distance < 20 )  {
36    FORWARD(255); 
37    distance = ultrasonic.read();
38    IR_front = analogRead(IR_sensor_front);
39    IR_back = analogRead(IR_sensor_back);
40    if ( IR_front > 650 || IR_back  > 650 ) { break;}
41    delay(10); }
42  
43  
44 if (IR_front < 650 )  // <  650 means white line
45   {
46   Stop();
47   delay (50);
48   BACKWARD(255);
49   delay (500);
50   } 
51   
52 if (IR_back < 650 )  //
53   {
54   Stop();
55   delay (50);
56   FORWARD(255);
57   delay (500);
58   }
59   
60   /* -----------  debugging ----------------
61  Serial.print(ultrasonic.Ranging(CM));
62  Serial.println("cm");
63  Serial.println("IR front :");
64  Serial.println(IR_front); 
65  Serial.println("IR  back :");
66  Serial.println(IR_back);  
67*/ 
68
69} //--------------------------------------------
70void  FORWARD (int Speed){
71  //When we want to let Motor To move forward,
72  // just  void this part on the loop section .
73  analogWrite(IN1,Speed);
74  analogWrite(IN2,0);
75  analogWrite(IN3,0);
76  analogWrite(IN4,Speed);
77}//--------------------------------------------
78void  BACKWARD (int Speed){
79  //When we want to let Motor To move forward,
80  //  just void this part on the loop section .
81  analogWrite(IN1,0);
82  analogWrite(IN2,Speed);
83  analogWrite(IN3,Speed);
84  analogWrite(IN4,0);
85}//--------------------------------------------
86void  ROTATE (int Speed)
87{
88  //When we want to let Motor To Rotate ,
89  // just  void this part on the loop section .
90  analogWrite(IN1,Speed);
91  analogWrite(IN2,0);
92  analogWrite(IN3,Speed);
93  analogWrite(IN4,0);
94}//--------------------------------------------
95void  Stop(){
96  //When we want to  Motor To stop ,
97  // just void this part on the  loop section .
98  analogWrite(IN1,0);
99  analogWrite(IN2,0);
100  analogWrite(IN3,0);
101  analogWrite(IN4,0);
102}