//QTRSensors folder must be placed in your arduino libraries folder
#include <QTRSensors.h> // Pololu QTR Library
//line sensor defines
#define NUM_SENSORS 8 // number of sensors used
#define TIMEOUT 2500 // waits for 2500 microseconds for sensor outputs to go low
#define EMITTER_PIN QTR_NO_EMITTER_PIN // emitter control pin not used. If added, replace QTR_NO_EMITTER_PIN with pin#
// line sensor declarations
// sensors 0 through 7 are connected to digital pins 2 through 10, respectively (pin 3 is skipped and used by the Ardumoto controller)
// 0 is far Right sensor while 7 is far Left sensor
QTRSensorsRC qtrrc((unsigned char[]) {10,9,8,7,6,5,4,2},NUM_SENSORS, TIMEOUT, EMITTER_PIN);
unsigned int sensorValues[NUM_SENSORS]; // array with individual sensor reading values
unsigned int line_position=0; // value from 0-7000 to indicate position of line between sensor 0 - 7
// ArduMoto motor driver vars
// pwm_a/b sets speed. Value range is 0-255. For example, if you set the speed at 100 then 100/255 = 39% duty cycle = slow
// dir_a/b sets direction. LOW is Forward, HIGH is Reverse
int pwm_a = 3; //PWM control for Ardumoto outputs A1 and A2 is on digital pin 10 (Left motor)
int pwm_b = 11; //PWM control for Ardumoto outputs B3 and B4 is on digital pin 11 (Right motor)
int dir_a = 12; //direction control for Ardumoto outputs A1 and A2 is on digital pin 12 (Left motor)
int dir_b = 13; //direction control for Ardumoto outputs B3 and B4 is on digital pin 13 (Right motor)
// motor tuning vars
int calSpeed = 165; // tune value motors will run while auto calibration sweeping turn over line (0-255)
// Proportional Control loop vars
float error=0;
float lastError=0;
float PV =0 ;
float kp = 0;
float ki = 0;
float kd =0;
int m1Speed=0;
int m2Speed=0;
//int line_position=0;
int motorspeed=0;
void setup()
{
//Set control pins to be outputs
pinMode(pwm_a, OUTPUT);
pinMode(pwm_b, OUTPUT);
pinMode(dir_a, OUTPUT);
pinMode(dir_b, OUTPUT);
//set both motors to stop
analogWrite(pwm_a, 0);
analogWrite(pwm_b, 0);
// delay to allow you to set the robot on the line, turn on the power,
// then move your hand away before it begins moving.
delay(2000);
// calibrate line sensor; determines min/max range of sensed values for the current course
for (int i = 0; i <= 100; i++) // begin calibration cycle to last about 2.5 seconds (100*25ms/call)
{
// auto calibration sweeping left/right, tune 'calSpeed' motor speed at declaration
// just high enough all sensors are passed over the line. Not too fast.
if (i==0 || i==60) // slow sweeping turn right to pass sensors over line
{
digitalWrite(dir_a, LOW);
analogWrite(pwm_a, calSpeed);
digitalWrite(dir_b, HIGH);
analogWrite(pwm_b, calSpeed);
}
else if (i==20 || i==100) // slow sweeping turn left to pass sensors over line
{
digitalWrite(dir_a, HIGH);
analogWrite(pwm_a, calSpeed);
digitalWrite(dir_b, LOW);
analogWrite(pwm_b, calSpeed);
}
qtrrc.calibrate(); // reads all sensors with the define set 2500 microseconds (25 milliseconds) for sensor outputs to go low.
} // end calibration cycle
// read calibrated sensor values and obtain a measure of the line position from 0 to 7000
line_position = qtrrc.readLine(sensorValues);
// read the value of only a single sensor to see the line.
// when the value is greater than 200 the sensor sees the line.
while (sensorValues[6] < 200) // wait for line position to near center
{
line_position = qtrrc.readLine(sensorValues);
}
// find near center
while (line_position > 4350) // continue loop until line position is near center
{
line_position = qtrrc.readLine(sensorValues);
}
// stop both motors
analogWrite(pwm_b, 0); // stop right motor first which kinda helps avoid over run
analogWrite(pwm_a, 0);
// delay as indicator setup and calibration is complete
delay(1000);
} // end setup
void loop() // main loop
{
// read calibrated sensor values and obtain a measure of the line position from 0 to 7000
unsigned int line_position = qtrrc.readLine(sensorValues);
// begin line
follow_line(line_position);
} // end main loop
void follow_line(int line_position) //follow the line
{
// 0 is far Right sensor while 7 (7000 return) is far Left sensor
switch(line_position)
{
// Line has moved off the left edge of sensor
// This will make it turn fast to the left
case 7000:
digitalWrite(dir_a, HIGH);
analogWrite(pwm_a, 200);
digitalWrite(dir_b, LOW);
analogWrite(pwm_b, 200);
break;
// Line had moved off the right edge of sensor
// This will make it turn fast to the right
case 0:
digitalWrite(dir_a, LOW);
analogWrite(pwm_a, 200);
digitalWrite(dir_b, HIGH);
analogWrite(pwm_b, 200);
break;
// The line is still within the sensors.
// This will calculate adjusting speed to keep the line in center.
default:
error = (float)line_position - 3500;
// set the motor speed based on proportional and derivative PID terms
// kp is the a floating-point proportional constant (maybe start with a value around 0.5)
// kd is the floating-point derivative constant (maybe start with a value around 1)
// note that when doing PID, it's very important you get your signs right, or else the
// control loop will be unstable
kp=1/20;
kd=2/3;
PV = kp * error + kd * (error - lastError);
lastError = error;
//this codes limits the PV (motor speed pwm value)
// limit PV to 55
if (PV > 55)
{
PV = 55;
}
if (PV < -55)
{
PV = -55;
}
m1Speed = 200 + PV;
m2Speed = 200 - PV;
//set motor speeds
digitalWrite(dir_a, HIGH);
analogWrite(pwm_a, m1Speed);
digitalWrite(dir_b, HIGH);
analogWrite(pwm_b, m2Speed);
break;
}
} // end follow_line
here is my code for follow black line on white surface could u pls tell me what are the changes that I have to do to follow white line
