Efficient wall-following robot with ultrasonic sensor that works indoors and outdoors

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 //Program to

 #include

 #define SONAR_NUM 2 //defines the number of ultrasonic sensors used
 #define MAX_DISTANCE 800 //Maximum distance between the object and the robot
 #define PING_INTERVAL 33

 #define trigPin1 6 // define pin connections for sensor and motor
 #define echoPin1 5
 #define trigPin2 11
 #define echoPin2 10
 #define LM1 2
 #define LM23
 #define RM1 7
 #define RM2 8

 int rangeFront = 0;
 int rangeWall = 0;

 Sonar NewPing(SONAR_NUM) = { // Define a Newping array to measure distance
 NewPing(trigPin1, echoPin1, MAX_DISTANCE),
 NewPing(trigPin2, echoPin2, MAX_DISTANCE)
 };
 void setup // configuration function to configure the pin to define whether it is input or output
 {
 Serial.begin(9600);
 int i;
 
pinMode(LM1, OUTPUT);
 pinMode(LM2, OUTPUT);
 pinMode(RM1, OUTPUT);
 pinMode(RM2, OUTPUT);
 pinMode(en1, OUTPUT);
 pinMode(pt2, OUTPUT);

 pinMode(trigPin1, OUTPUT);
 pinMode(echoPin1, INPUT);
 digitalWrite(trigPin1, LOW);

 pinMode(trigPin2, OUTPUT);
 pinMode(echoPin2, INPUT);
 digitalWrite(trigPin2, LOW);
 }

 int toCloseWall = 1800; //Initialize and define the values ​​of the distance between the wall and the robot
 int for FarWall = 2500;
 int toCloseFront = 1000;

 empty loop
 {
 Main:
 rangeFront = readRangeFront ; // Read the sensor value by calling the function
 Serial.print(rangeFront);
 Serial.print("Front");
 Serial.println;
 rangeWall = readRangeWall ;
 Serial.print(rangeWall);
 Serial.print("Wall");
 Serial.println;

 if (rangeFront <= 400) //As the sensor value reads the small values, we are manipulating to high values
 {
 rangeFront = 3000;
 }
 if(intervalWall <= 400)
 {
 wallrange = 3000;
 }

 
if (rangeFront < toCloseFront) //Condition to check if the front sensor is close to the robot
 {
 delay(500);
 drive_backward;
 delay(500);
 Serial.print("Back");
 //Turn right ;
 Serial.print("Turn right");
 Serial.println;
 delay(800);
 move on;
 Turn left ;
 delay(1700);
 go to Main;
 }

 if(rangeWall > toCloseWall && rangeWall < toFarWall) //condition to check if the distance measured by the front and side sensor is maintained correctly
 {
 move on;
 Serial.print("Next");
 Serial.println;
 go to Main;
 }

 if (rangeWall < toCloseWall) //condition to check if the side wall is close to the robot
 {
 delay(100);
 //Turn left ;
 Turn right ;
 delay(500);
 Serial.print("Turn Left");
 move on;
 Serial.print("Next");
 Serial.println;
 go to Main;
 }
 
if (rangeWall > toFarWall) //condition to check if the robot is far from the side wall
 {
 delay(100);
 //Turn right ;
 Turn left ;
 Serial.print("Turn right");
 delay(500);
 move on;
 Serial.print("Next");
 Serial.println;
 go to Main;
 }
 }

 void motor_stop // function to stop the robot
 {
 digitalWrite(LM1, DOWN);
 digitalWrite(LM2, DOWN);
 digitalWrite(RM1, LOW);
 digitalWrite(RM2, LOW);
 }

 void drive_forward // function to drive the robot forward
 {
 digitalWrite(LM1, HIGH);
 digitalWrite(LM2, DOWN);
 digitalWrite(RM1, HIGH);
 digitalWrite(RM2, LOW);
 }

 void drive_backward // function to drive the robot backwards
 {
 digitalWrite(LM1, DOWN);
 digitalWrite(LM2, HIGH);
 digitalWrite(RM1, LOW);
 digitalWrite(RM2, HIGH);
 }

 void turn_left // function to turn the robot left
 {
 digitalWrite(LM1, HIGH);
 digitalWrite(LM2, DOWN);
 digitalWrite(RM1, LOW);
 
digitalWrite(RM2, LOW);
 }

 void turn_right //function to turn the robot to the right
 {
 digitalWrite(LM1, DOWN);
 digitalWrite(LM2, DOWN);
 digitalWrite(RM1, HIGH);
 digitalWrite(RM2, LOW);
 }

 int readRangeFront //function to read the front sensor value
 {
 delay(50);
 unsigned rangeFront = sonar(0).ping ;
 sonar(0).timer_stop ;
 return rangeFront;
 }
 int readRangeWall // function to read the left sensor value
 {
 delay(50);
 unsigned rangeWall = sonar(1).ping ;
 sonar(1).timer_stop ;
 return rangeWall;
 }


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