Line Follower with Obstacle avoidance capability HELP !!!!!

Projects Programming
1

Hello ! I recently started on a project related to line follower robot. I have searched various sources available on the internet and found instructable's http://www.instructables.com/id/Arduino-based-line-follower-using-Pololu-QTR-8RC-l/ to be much helpful. I tested it out and the line follower works perfectly. Curious enough i wanted to incorporate an obstacle avoider fuction to the robot as well incase there is some obstacle on the line. For this i bought an ULTRASONIC sensor. I checked the sensor separately and tested it for a specific distance which will turn on an LED. Worked beautifully as well so i merged the obstacle avoider code with the Line follower code.I altered the code so that at a specific distance the robot will stop. NOW HERE COMES MY PROBLEM !!!

When i start the robot although the robot stops at a specific distance however the line following is not that GREAT. It follows the line barely. Now i am no CODE GURU but by my understanding the obstacle avoider fuction is causing a delay in the line follower function.

I have searched the internet for some clues but havent yet rectified the problem. I HOPE THE GOOD PEOPLE OF THIS FORUM WOULD HELP ME SOLVE THIS. :slight_smile: AGAIN i am not a programming expert but have a pretty basic self taught knowledge so if i have made a STUPID mistake it was not intentional. :slight_smile:

Following is my code which produces the delay in line following.

#include <QTRSensors.h>
#include <AFMotor.h>
#include <Ultrasonic.h>

#define TRIGGER_PIN 46 // Pin defining at pin 46 and pin 44
#define ECHO_PIN 44

AF_DCMotor motor1(1, MOTOR12_8KHZ ); // PIN 11 - create motor #1 pwm
AF_DCMotor motor2(2, MOTOR12_8KHZ ); // PIN 3 - create motor #2 pwm
Ultrasonic ultrasonic(TRIGGER_PIN, ECHO_PIN);

const int dangerThresh = 10; // danger distance 10 cm

// Change the values below to suit your robot's motors, weight, wheel type, etc.
#define KP .2
#define KD 5
#define M1_DEFAULT_SPEED 90
#define M2_DEFAULT_SPEED 90
#define M1_MAX_SPEED 110
#define M2_MAX_SPEED 110
#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

QTRSensorsRC qtrrc((unsigned char[]) { A8, A9, A10, A11, A12, A13, A14, A15} ,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)
{
float cmMsec;

// ALOGRATHM FOR conversion of time to distance
long microsec = ultrasonic.timing();
cmMsec = ultrasonic.convert(microsec, Ultrasonic::CM);

if (cmMsec>dangerThresh)
{
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);
}
else
{
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(RELEASE);
motor2.run(RELEASE);
}

}

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*);*

  • Serial.print(' ');*
  • }*
  • Serial.println();*
  • for (int i = 0; i < NUM_SENSORS; i++)*
  • {*
    _ Serial.print(qtrrc.calibratedMaximumOn*);_
    _     Serial.print(' ');_
    _     }_
    _     Serial.println();_
    _     Serial.println();_
    _     }_
    _    }_
    _    [/quote]*_
2

I'd suggest that you comment out the calls to the ultrasonic code and set cmMsec to 100 so you can verify whether the line following works properly by itself.

Then you'll need to look at the code in the ultrasonic library. It's bound to have some delays in it. You may find though that it's doing multiple pings and averaging them - if so you may want to look at some ping code and produce a simpler version of your own that doesn't take so long.

3

i also having the same problem.
now what is the solution u found?