So I have this code for a Line Following robot. If it’s a black line, it works perfectly. It doesn’t if it’s a white line.
I read in the libraries that to read a white line, this line of code is necessary:
unsigned int position = qtrrc.readLine(sensorValues, QTR_EMITTERS_ON, 1);
My question is:
Is changing this line of code enough? do I need to change anything else in the following code?:
#include <PololuQTRSensors.h>
#include <AFMotor.h>
AF_DCMotor motor1(1, MOTOR12_8KHZ ); // PIN 11 - create motor #1 pwm
AF_DCMotor motor2(2, MOTOR12_8KHZ ); // PIN 3 - create motor #2 pwm
// Change the values below to suit your robot’s motors, weight, wheel type, etc.
#define KP .2
#define KD 5
#define M1_DEFAULT_SPEED 50
#define M2_DEFAULT_SPEED 50
#define M1_MAX_SPEED 70
#define M2_MAX_SPEED 70
#define MIDDLE_SENSOR 3
#define NUM_SENSORS 5 // number of sensors used
#define TIMEOUT 2500 // waits for 2500 us for sensor outputs to go low
#define EMITTER_PIN 2 // emitter is controlled by digital pin 2
#define DEBUG 0 // set to 1 if serial debug output needed
PololuQTRSensorsRC qtrrc((unsigned char[]) { 18,17,16,15,14} ,NUM_SENSORS, TIMEOUT, EMITTER_PIN);
unsigned int sensorValues[NUM_SENSORS];
void setup()
{
delay(1000);
manual_calibration();
set_motors(0,0);
}
int lastError = 0;
int last_proportional = 0;
int integral = 0;
void loop()
{
unsigned int sensors[5];
int position = qtrrc.readLine(sensors);
int error = position - 2000;
int motorSpeed = KP * error + KD * (error - lastError);
lastError = error;
int leftMotorSpeed = M1_DEFAULT_SPEED + motorSpeed;
int rightMotorSpeed = M2_DEFAULT_SPEED - motorSpeed;
// set motor speeds using the two motor speed variables above
set_motors(leftMotorSpeed, rightMotorSpeed);
}
void set_motors(int motor1speed, int motor2speed)
{
if (motor1speed > M1_MAX_SPEED ) motor1speed = M1_MAX_SPEED; // limit top speed
if (motor2speed > M2_MAX_SPEED ) motor2speed = M2_MAX_SPEED; // limit top speed
if (motor1speed < 0) motor1speed = 0; // keep motor above 0
if (motor2speed < 0) motor2speed = 0; // keep motor speed above 0
motor1.setSpeed(motor1speed); // set motor speed
motor2.setSpeed(motor2speed); // set motor speed
motor1.run(FORWARD);
motor2.run(FORWARD);
}
void manual_calibration() {
int i;
for (i = 0; i < 250; i++) // the calibration will take a few seconds
{
qtrrc.calibrate(QTR_EMITTERS_ON);
delay(20);
}
if (DEBUG) { // if true, generate sensor dats via serial output
Serial.begin(9600);
for (int i = 0; i < NUM_SENSORS; i++)
{
Serial.print(qtrrc.calibratedMinimumOn[i]);
Serial.print(’ ');
}
Serial.println();
for (int i = 0; i < NUM_SENSORS; i++) { Serial.print(qtrrc.calibratedMaximumOn[i]); Serial.print(' '); } Serial.println(); Serial.println();}
}