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I'm very new about this thing. I have made an arduino robot car for my assignment. There is a maze that I have to complete it. I'm using L298N Dual H-Bridge Motor Driver, Servo Motor, HC-SR04 Ultrasonic Sensor, DC Motor, Arduino Sensor Shield.

The problem when in the maze is, the sensor will check if there is wall front of the car. Then it will scan from left, then right. BUT, the maze was straight line and at the middle, has one way out.

I have a problem on how to make the sensor detect the 180 degree of wall every second. What I mean is, when the car move ahead inch, the sensor will scan left, front, right. Then, if there is a wall at left, the car move ahead inch, then scan again. I really need help for this assignment.

Figure 1 Figure 2

Here is my code:

#include <Servo.h> 
// Pins for the Echo Sensor
#define TRIG_PIN A0
#define ECHO_PIN A1 
//Define all the connections maps to the L298N
#define enA 13
#define in1 12
#define in2 11
#define in3 7
#define in4 6
#define enB 5
#define servoPin 2

class Motor{

int enablePin;
int directionPin1;
int directionPin2;

public:

//Methods to define motor pins
Motor(int ENPin,int dPin1,int dPin2){
enablePin = ENPin;
directionPin1 = dPin1;
directionPin2 = dPin2;
};




//Method to allow robot to turn and move forward and backwards
void Drive(int speed){
if(speed>=0){
digitalWrite(directionPin1, LOW);
digitalWrite(directionPin2, HIGH);
}
else{
digitalWrite(directionPin1, HIGH);
digitalWrite(directionPin2, LOW);
speed = - speed;
}
analogWrite(enablePin, speed);
}
};

Motor leftMotor = Motor(enA, in1, in2);
Motor rightMotor = Motor(enB, in3, in4);
Servo myservo; // create servo object to control a servo

void motorInitiation(){
pinMode(enA, OUTPUT);
pinMode(in1, OUTPUT);
pinMode(in2, OUTPUT);
pinMode(enB, OUTPUT);
pinMode(in3, OUTPUT);
pinMode(in4, OUTPUT);
// Set initial direction and speed
digitalWrite(enA, LOW);
digitalWrite(enB, LOW);
digitalWrite(in1, LOW);
digitalWrite(in2, HIGH);
digitalWrite(in3, LOW);
digitalWrite(in4, HIGH);
}

//Variables--------------------------------------------------------------------------
// Anything over 400 cm (23200 us pulse) is "out of range"
const unsigned int MAX_DIST = 23200;
bool ObsticalAhead = false;
int servoPos = 90;

enum Directions { Forward, TurnLeft, TurnRight, TurnAround,Brake};

Directions nextStep = Forward;

unsigned long t1;
unsigned long t2;
unsigned long pulse_width;
float cm;
float inches;

//SETUP--------------------------------------------------------------------------
void setup() {

// The Trigger pin will tell the sensor to range find
pinMode(TRIG_PIN, OUTPUT);
digitalWrite(TRIG_PIN, LOW);

// Serial monitor to view the sensor output
Serial.begin(9600);
myservo.attach(servoPin);
motorInitiation();
Directions nextStep = Forward;
}

void loop() {

checkDistance();
checkDirection();
drive();
}

void checkDistance(){

// Hold the trigger pin high for at least 10 us
digitalWrite(TRIG_PIN, HIGH);
delayMicroseconds(10);
digitalWrite(TRIG_PIN, LOW);

// Wait for pulse on echo pin
while ( digitalRead(ECHO_PIN) == 0 );

// Measures how long the echo pin was held high (pulse width)
t1 = micros();
while ( digitalRead(ECHO_PIN) == 1);
t2 = micros();
pulse_width = t2 - t1;

// Calculate distance in centimeters and inches from sound to bounce back
cm = pulse_width / 58.0;
inches = pulse_width / 148.0;

// Print out results
if ( pulse_width > MAX_DIST ) {
//Serial.println("Out of range");
} else {
//Serial.print(cm);
//Serial.print(" cm \t");
//Serial.print(inches);
//Serial.println(" in");
}

// Wait at least 60ms before next measurement
delay(60);

if(cm<= 20){
ObsticalAhead = true;
Serial.println("Problem Ahead");

}
else{ ObsticalAhead = false;}

}
void checkDirection(){
Serial.println("checking direction");
if(ObsticalAhead ==true){ 
nextStep = Brake;
drive();
myservo.write(180); // tell servo to go to position in variable 'pos'
delay(400); // waits 15ms for the servo to reach the position
checkDistance();
if(ObsticalAhead ==false){//if left side is open
nextStep = TurnLeft;
Serial.println("Next step is TurnLeft");
myservo.write(90);//reset servo position
delay(400);
}
else{// left is blocked, now need to look at right
myservo.write(0); // tell servo to go to position in variable 'pos'
delay(800); // waits 15ms for the servo to reach the position
checkDistance();
if(ObsticalAhead ==false){//if right side is open
nextStep = TurnRight;
Serial.println("Next step is TurnRight");
myservo.write(90);//reset servo position
delay(400); 
}
else{//right is blocked as well, need to turn around
nextStep = TurnAround;
myservo.write(90);//reset servo position
delay(300);
Serial.println("Next step is TurnAround");
}
}

}
else{nextStep = Forward;}//No obstical ahead
}

void drive(){
switch (nextStep){
case Forward:
leftMotor.Drive(255);
rightMotor.Drive(255);
Serial.println("Forward");

break;
case TurnLeft:
leftMotor.Drive(-255);
rightMotor.Drive(255);
Serial.println(" TurnLeft");
delay(400);

break;
case TurnRight:
leftMotor.Drive(255);
rightMotor.Drive(-255);
Serial.println(" TurnRight");
delay(400);
break;
case TurnAround:
leftMotor.Drive(255);
rightMotor.Drive(-255); 
Serial.println(" TurnAround");
delay(600);
break;

case Brake:
leftMotor.Drive(0);
rightMotor.Drive(0);
Serial.println(" stopped");
} 
}
  • 1
    Tip: break your program down into smaller functions and "unit test" them. Make sure that each component of your program does what you expect it to, then make them all work together. – Majenko May 30 '18 at 9:37
  • 2
    I am not sure from your description what the problem is. What is it not doing that it should, or doing that it shouldnt? – Chad G May 30 '18 at 15:08

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