Line following Car that can automatically stop

Projects Programming
1 
#define LT_R !digitalRead(10)
#define LT_M !digitalRead(4)
#define LT_L !digitalRead(2)

#define ENA 5
#define ENB 6
#define IN1 7
#define IN2 8
#define IN3 9
#define IN4 11

#define carSpeed 150

void forward(){                //car drives forward
  analogWrite(ENA, carSpeed);
  analogWrite(ENB, carSpeed);
  digitalWrite(IN1, HIGH);
  digitalWrite(IN2, LOW);
  digitalWrite(IN3, LOW);
  digitalWrite(IN4, HIGH);
  Serial.println("vorwärts");
}

void back(){                   //car drives backwards, dont have a use yet.
  analogWrite(ENA, carSpeed);  //But i thought about it searching for the line by driving backwards/forwards for a short moment
  analogWrite(ENB, carSpeed);
  digitalWrite(IN1, LOW);
  digitalWrite(IN2, HIGH);
  digitalWrite(IN3, HIGH);
  digitalWrite(IN4, LOW);
  Serial.println("rückwärts");
}

void left(){                   //car drives left
  analogWrite(ENA, carSpeed);
  analogWrite(ENB, carSpeed);
  digitalWrite(IN1, LOW);
  digitalWrite(IN2, HIGH);
  digitalWrite(IN3, LOW);
  digitalWrite(IN4, HIGH);
  Serial.println("left");
}

void right(){                   //car drives right
  analogWrite(ENA, carSpeed);
  analogWrite(ENB, carSpeed);
  digitalWrite(IN1, HIGH);
  digitalWrite(IN2, LOW);
  digitalWrite(IN3, HIGH);
  digitalWrite(IN4, LOW);
  Serial.println("right");
}

void brake(){              //car stopping
  digitalWrite(ENA, LOW);
  digitalWrite(ENB, LOW);
  Serial.println("stop");
}  
void setup(){              //setup for the line detection
  pinMode(LT_R,INPUT);
  pinMode(LT_M,INPUT);
  pinMode(LT_L,INPUT);
}

void loop() {       //Loop that makes the car follow the line
  if(LT_M){
  forward();
  }
  else if(LT_L){    //car drives left 
    left();
    while (LT_L);
   }
  else if (LT_R){    //car drives right
    right();
    while(LT_R);
  }
  else {             //car brakes if it cant detect the line,
    brake();         //currently it stops if it doesnt detect it for even the slightest moment
 }					 //This makes the car unable to follow the line properly
}					 //i want it to stop only if it doesnt detect it for longer than lets say 0.5 - 1 second

Alright this is the Code, its purpose is to make the car follow a black line using 3 sensors at the front. It works decently following the Line but now i wan't it to stop once it doesnt detect it.
I used a simple else at the end that makes the car stop once it doesn't detect the line but this work too well as the car stop even at the slightest.

I have thought about potetntially adding a timer that runs down once it doesnt detect the line and then stops the car. However i am pretty new to programming and my attempts failed wich involved using integers (int i = 0; i >=500; i++) but that didnt work for me.

At one point i had it happen where the car just spins to the right once it goes off-track but im an idiot and accidentally deleted that part..

i would appreciate any help :slight_smile:

2

You need to keep track of how many times in a row you land in the 'else` part of your code and then, if this gets large enough, brake.

Some thing like this:

unsigned int brake_count = 0;
const unsigned int brake_count_limit = 1000;  // some number you need to figure out
void loop() {       //Loop that makes the car follow the line
  if(LT_M){
    forward();
    brake_count = 0; // line found
  }
  else if(LT_L){    //car drives left 
    left();
    brake_count = 0; // line found
    while (LT_L);
   }
  else if (LT_R){    //car drives right
    right();
    brake_count = 0; // line found
    while(LT_R);
  }
  else {             //car brakes if it cant detect the line,
    brake_count++;
  if ( brake_count >= brake_count_limit ) {
    brake(); 
    while(1); // loop forever
  }
 }					 //This makes the car unable to follow the line properly
}					 //i want it to stop only if it doesnt detect it for longer than lets say 0.5 - 1 second
1 Like
3

Wow thank you, i‘ll try this as soon as i can. Unfortunately earliest i can test it is tuesday as the arduino cars are at school and i do not own one haha.

I‘ll update this thread if it works!

4

instead of reversing a motor to change direction, what about slowing one motor down?

enum { DirFor = LOW, DirRev = HIGH };

void move (
    int   speedLeft,
    int   speedRight,,
    int   direction )
{
    Serial.println ("vorwärts");

    digitalWrite (IN1, ! direction);
    digitalWrite (IN2,   direction);
    digitalWrite (IN3,   direction);
    digitalWrite (IN4, ! direction);

    analogWrite (ENA, speedLeft);
    analogWrite (ENB, speedRight);
}

and shouldn't you monitor the outside sensors to keep moving forward (not sure what if sensor is HIGH/LOW when on the line)

void loop () {
    if (! LT_L && ! LT_R)
        move (SpdNorm, SpdNorm, DirFor);

no need for a while loop to turn

    else if (LT_L)
        move (SpdNorm, SpdLow, DirFor);

but may want to undo any turn for probably half the time a correction was made

may want to turn harder if the middle sensor is also off the line

    else if (LT_L && LT_M )
        move (SpdNorm, SpdVeryLow, DirFor);
    else if (LT_L)
        move (SpdNorm, SpdLow, DirFor);

no need for brake()

        move (0, 0, DirFor);

@blh64 seems simple enough

5

Expand the macro.

How does that work?
What about the outputs?
Edit: talk to this guy - their code looks a lot like yours

Edit to edit: re-reading this topic, it looks like you're having an identity crisis.
Thoughts and prayers.

7

So about expanding the macro,

LT_L/R/M are just three infrared sensors that detect the line, or rather dark and bright. There is no output for those so its only as an input.

8

Now, expand the macro with the pinMode.

9

what does digitalRead() return and what pin # is being passed to pinMode()? (shouldn't it be 10, 4, or 2)?

not sure any of the comments are of any value if the code doesn't work

10

as far as i understand what happens here:

It creates the constant values LT_L/M/R, these get a value from the pins 10,4,2 (the 3 infrared sensors under the car).

and with pinMode it just uses these pins values through the previously defined LT_L/M/R

the code works as it is and the car follows the line, im just trying to figure out how to make it stop without it stopping suddenly in a curve.

11

can you elaborate on what you mean by expanding the macro? im pretty new so i only got the basic basics down haha

12

the #define describes text that is replaced everywhere in the code with the defined value. in other words

  pinMode (!digitalRead(10);
  pinMode (!digitalRead(4));
  pinMode (!digitalRead(2));
13

so is pinMode(digitalRead(10), the same as pinMode(LT_R, or is it different? and if so how different is it?

14

it's pinMode (! digitalRead (10)); that the define is

it's exactly the same.
don't know why you think LT_R is somehow just the pin# when used in pinMode()

15

What about all those pins you're using a digitalWrite on? (IN1 to IN4)

16

those are the pins for the servo motors, ENA and ENB control the speed of the left and right side and IN1-4 are the 4 motors that spin the wheel

17

But you want them to be outputs, right?
You don't just want to turn the pullup resistors on an input on and off.

18

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