Line-Following Sensor Movement Code

// hint: see how this person changed the code for their robot: http://www.techbitar.com/fast-line-following-robot.html

#include <QTRSensors.h>
#include <YD_MotorDriver1.h>

#define NUM_SENSORS  6     // number of sensors used
#define TIMEOUT   2500
#define EMITTER_PIN  QTR_NO_EMITTER_PIN  // or 2 if you want to use this feature

#define  Motor1A  8  
#define  Motor1B  7
#define  Motor2C  6
#define  Motor2D  5

#define  StartMoveSpeed    200
#define  SlowMoveSpeed     280
#define  SlowMoveAdjust     5   //determine the adjustment factors to use
#define  MediumMoveSpeed   300
#define  MediumMoveAdjust   5  
#define  FastMoveSpeed     350
#define  FastMoveAdjust    5
#define  MaxMoveSpeed     385
#define  MaxMoveAdjust     5

YD_MotorDriver1 RobotDriver(Motor1A,Motor1B,Motor2C,Motor2D);

// sensor connected through analog pins A0 - A5 i.e. digital pins 14-19
QTRSensorsRC qtrrc((unsigned char[]) {14, 15, 16, 17, 18, 19}, NUM_SENSORS, TIMEOUT, EMITTER_PIN); 

unsigned int sensorValues[NUM_SENSORS];

void setup()
{
   RobotDriver.init();

   delay(500);
   pinMode(13, OUTPUT);
   digitalWrite(13, HIGH);    // turn on Arduino's LED to indicate we are in calibration mode
   for (int i = 0; i < 400; i++)  // make the calibration take about 10 seconds
   {
    qtrrc.calibrate();     // reads all sensors 10 times at 2500 us per read (i.e. ~25 ms per call)
    delay(20);
   }
   digitalWrite(13, LOW);   // turn off Arduino's LED to indicate we are through with calibration
 
   delay(2000);          //allow time to position the robot
}
void loop()
{
  unsigned int sensors[NUM_SENSORS];
  int position = qtrrc.readLine(sensors);
  int error = position - 2500; // you may need to adjust this factor
  int errorMargin  = 100;      // you may need to adjust this factor
  int delayAmount = 1000;      // you WILL need to adjust this


  if(error > errorMargin)               
  {
   //code turn to left
    TurnLeft(delayAmount);   // QUIZ:  determine value to use
  }
  else if(error < -errorMargin)
  {
    //code turn to right
    TurnRight(delayAmount);    // QUIZ:  determine value to use
  }
  else
  {
     // code to go straight 
     // if you want to go faster or slower, use the relevant code
     ForwardMedium(delayAmount);
  }

}


void ForwardSlow(int howLong)
{
  RobotDriver.Motor1Speed(SlowMoveSpeed + SlowMoveAdjust);
  RobotDriver.Motor2Speed(SlowMoveSpeed - SlowMoveAdjust); 
  delay(howLong);
  Stop(); 
}
/*---------------------------*/

void ForwardMedium(int howLong)
{
  RobotDriver.Motor1Speed(MediumMoveSpeed + MediumMoveAdjust);
  RobotDriver.Motor2Speed(MediumMoveSpeed - MediumMoveAdjust); 
  delay(howLong);
  Stop(); 
}
/*---------------------------*/
void ForwardFast(int howLong)
{
  RobotDriver.Motor1Speed(FastMoveSpeed + FastMoveAdjust);
  RobotDriver.Motor2Speed(FastMoveSpeed - FastMoveAdjust); 
  delay(howLong);
  Stop(); 
}
/*---------------------------*/
void BackwardSlow(int HowMuch)
{
  RobotDriver.Motor1Speed(- SlowMoveSpeed );
  RobotDriver.Motor2Speed(- SlowMoveSpeed ); 
  delay(HowMuch);
  Stop();  
}
/*---------------------------*/
void BackwardMedium(int HowMuch)
{
  RobotDriver.Motor1Speed(- MediumMoveSpeed);
  RobotDriver.Motor2Speed(- MediumMoveSpeed); 
  delay(HowMuch);
  Stop(); 
}
/*---------------------------*/
void BackwardFast(int HowMuch)
{
  RobotDriver.Motor1Speed(- FastMoveSpeed);
  RobotDriver.Motor2Speed(- FastMoveSpeed); 
  delay(HowMuch);
  Stop(); 
}
/*---------------------------*/
void Stop()
{
  RobotDriver.Motor1Speed(0);
  RobotDriver.Motor2Speed(0); 
}
/*---------------------------*/
void SpinLeft(int HowMuch)
{
  RobotDriver.Motor1Speed(MediumMoveSpeed);
  RobotDriver.Motor2Speed(- MediumMoveSpeed);
  delay(HowMuch);
  Stop();
}
/*---------------------------*/
void SpinRight(int HowMuch)
{
  RobotDriver.Motor1Speed(MediumMoveSpeed);
  RobotDriver.Motor2Speed(- MediumMoveSpeed);
  delay(HowMuch);
  Stop(); 
}


// *** Turn left and right functions - you will need to experiment with these ***

void TurnLeft(int howLong)
{
  RobotDriver.Motor1Speed(0);
  RobotDriver.Motor2Speed(MediumMoveSpeed);
  delay(howLong);
  Stop();
}

void TurnRight(int howLong)
{
  RobotDriver.Motor1Speed(MediumMoveSpeed);
  RobotDriver.Motor2Speed(0);
  delay(howLong);
  Stop(); 
}