Tim Rueger's entry for the TexLUG Austin
Lego Sumo Robotics contest, held 6/12/05.

See:

  http://www.brickshelf.com/cgi-bin/gallery.cgi?f=132763
  http://www.io.com/~rueger/lego/texlugaustin/meetings/0506.html

for contest photos and a summary of the contest.  The
contest rule set is found here:

  http://www.io.com/~rueger/lego/texlugaustin/sumo2005/sumobot_ruleset_050517.pdf

NQC code is below.

------------------------------------------------------------

// tim's 2-pound sumo bot for 050612 contest
// avoid black lines, turn toward a bump
// gearshift down when bumped
// gearshift up when hitting the border
// wiggle out of a jam after a timeout

// motors
#define Right   OUT_A   // right motor
#define Shifter OUT_B   // gear shifter motor
#define Left    OUT_C   // left motor

// sensors: piggyback light and touch
#define LTouch SENSOR_2
#define LLight SENSOR_2
#define RTouch SENSOR_3
#define RLight SENSOR_3

#define Touching 90           // touch sensor reads 100 when
                              // read as a light sensor

#define ShiftTime 200         // how long it takes to shift gears:
                              // 200/100 = 2.0 seconds

#define BorderReverseTime 75  // back up for 75/100 = 0.75 second
#define BorderTurnTime    150 // turn    for 150/100 = 1.5 seconds

#define BumpReverseTime 37    // back up for 37/100 = 0.37 second
#define BumpTurnTime    37    // turn    for 37/100 = 0.37 second

#define PanicTimeOut  50      // wiggle around if nothing happens after
                              // 50/10 = 5.0 seconds
#define PanicTurnTime 75      // turn for 75/100 = 0.75 second

// priority settings
#define LWatchLevel 0
#define RWatchLevel 1
#define LBumpLevel  2
#define RBumpLevel  3
#define PanicLevel  4

// power levels
#define MaxFwd  7
#define MaxRev  7
#define MaxTurn 7

// light sensor calibration
#define LIGHTMARGIN 7
int line=0;
int threshold=0;

// the state of the transmission - 1=high gear, 0=low gear
int gearshift=0;

task main()
{
   // initialize sensors
   SetSensor(LTouch,SENSOR_LIGHT);
   SetSensor(RTouch,SENSOR_LIGHT);
   SelectDisplay(DISPLAY_SENSOR_2); // display LLight reading

   // calibrate left light sensor with right touch
   Calibrate();

   // another right touch says "go!"
   until(RTouch>Touching);     // wait for right touch
   until(RTouch<Touching);     // wait for right release
   PlaySound(SOUND_CLICK);     // acknowledge: "let's go!"
   Wait(100);                  // wait for 100/100 = 1.0 seconds

   // start motors
   SetPower(Left+Right,MaxFwd);
   OnFwd(Left+Right);

   // clear panic timer
   ClearTimer(0);

   // start tasks
   start LWatch;     // watch for dark line on left
   start RWatch;     // watch for dark line on right
   start LBump;      // watch for touch on left
   start RBump;      // watch for touch on right
   start CheckPanic; // a panic timer

   // shift for fast speed
   SetPower(Shifter,MaxFwd);
   OnFwd(Shifter);
   Wait(ShiftTime);
   Off(Shifter);

   gearshift = 1; // start in high gear

}

// set the light/dark sensor readings for line avoidance
void Calibrate()
{
  // this is the "read the dark" button

  until(RTouch>Touching);      // wait for right touch

  line=LLight;                 // read left light
  threshold=line+LIGHTMARGIN;  // set light sensor threshold

  until(RTouch<Touching);      // wait for right release
  PlaySound(SOUND_CLICK);      // acknowledge: "I got it"
}

// watch for the black border on the left
task LWatch()
{
  SetPriority(LWatchLevel);
  while(true)
    {
      // watch for dark on the left light sensor
      until(LLight<=threshold);
      acquire(ACQUIRE_USER_1)
        {
          LAvoid();  // avoid the line on the left
        }
    }
}

// avoid the black border on the left
void LAvoid()
{

  SetPower(Left+Right,MaxRev);  // back up
  OnRev(Left+Right);
  Wait(BorderReverseTime);
  if (gearshift==0) {
    gearshift=1;
    SetPower(Shifter,MaxFwd);
    OnFwd(Shifter);             // gearshift up
    Wait(ShiftTime);
    Off(Shifter);
  }
  Off(Left+Right);

  SetPower(Left+Right,MaxTurn); // turn right
  OnFwd(Left);
  OnRev(Right);
  Wait(BorderTurnTime);

  SetPower(Left+Right,MaxFwd);  // go forward
  OnFwd(Left+Right);

  ClearTimer(0);
}

// watch for the black border on the left
task RWatch()
{
  SetPriority(RWatchLevel);
  while(true)
    {
      // watch for dark on the right light sensor
      until(RLight <= threshold);
      acquire(ACQUIRE_USER_1)
        {
          RAvoid();  // avoid the line on the right
        }
    }
}

// avoid the black border on the left
void RAvoid()
{
  SetPower(Left+Right,MaxRev);  // back up
  OnRev(Left+Right);
  Wait(BorderReverseTime);
  if (gearshift==0) {
    gearshift=1;
    SetPower(Shifter,MaxFwd);
    OnFwd(Shifter);             // gearshift up
    Wait(ShiftTime);
    Off(Shifter);
  }
  Off(Left+Right);

  SetPower(Left+Right,MaxTurn); // turn left
  OnFwd(Right);
  OnRev(Left);
  Wait(BorderTurnTime);

  SetPower(Left+Right,MaxFwd);  // go forward
  OnFwd(Left+Right);

  ClearTimer(0);
}

// watch for a touch on the left
task LBump()
{
  SetPriority(LBumpLevel);
  while(true)
    {
      // watch for a touch on the left touch sensor
      until(LTouch>Touching);
      if (gearshift == 1) {
        acquire(ACQUIRE_USER_1)
          {
            LTurn();  // turn toward the left and downshift
          }
      }
      ClearTimer(0);
    }
}

// turn toward the left, then gearshift down if needed
void LTurn()
{
  SetPower(Left+Right,MaxRev);  // back up
  OnRev(Left+Right);
  Wait(BumpReverseTime);
  Off(Left+Right);

  SetPower(Left+Right,MaxTurn); // turn left
  OnFwd(Right);
  OnRev(Left);
  Wait(BumpTurnTime);

  SetPower(Left+Right,MaxFwd);  // go forward
  OnFwd(Left+Right);

  if (gearshift==1) {
    gearshift=0;
    SetPower(Shifter,MaxFwd);
    OnRev(Shifter);             // gearshift down
    Wait(ShiftTime);
    Off(Shifter);
  }
}

// watch for a touch on the right
task RBump()
{
  SetPriority(RBumpLevel);
  while(true)
    {
      // watch for a touch on the right touch sensor
      until(RTouch>Touching);
      if (gearshift == 1) {
        acquire(ACQUIRE_USER_1)
          {
            RTurn();  // turn toward the right and downshift
          }
      }
      ClearTimer(0);
    }
}

// turn toward the right, then gearshift down if needed
void RTurn()
{
  SetPower(Left+Right,MaxRev);  // back up
  OnRev(Left+Right);
  Wait(BumpReverseTime);
  Off(Left+Right);

  SetPower(Left+Right,MaxTurn); // turn right
  OnFwd(Left);
  OnRev(Right);
  Wait(BumpTurnTime);

  SetPower(Left+Right,MaxFwd);  // go forward
  OnFwd(Left+Right);

  if (gearshift==1) {
    gearshift=0;
    SetPower(Shifter,MaxFwd);
    OnRev(Shifter);             // gearshift down
    Wait(ShiftTime);
    Off(Shifter);
  }
}

// the panic timer - if nothing has happened,
// then try to get out of the situation
task CheckPanic()
{
  SetPriority(PanicLevel);
  while(true)
    {
      // if the panic timer goes off
      until(Timer(0)>=PanicTimeOut);
      acquire(ACQUIRE_USER_1)
        {
          Wriggle();  // try to get out of trouble
        }
    }
}

// try to get out of a hangup position
void Wriggle()
{
  Off(Left);
  SetPower(Right,MaxTurn); // right motor reverse
  OnRev(Right);
  Wait(PanicTurnTime);

  Off(Right);
  SetPower(Left,MaxTurn);  // left motor reverse
  OnRev(Left);
  Wait(PanicTurnTime);

  Off(Left);
  SetPower(Right,MaxTurn); // right motor reverse
  OnRev(Right);
  Wait(PanicTurnTime);

  Off(Right);
  SetPower(Left,MaxTurn);  // left motor reverse
  OnRev(Left);
  Wait(PanicTurnTime);

  Off(Left);
  SetPower(Right,MaxTurn); // right motor reverse
  OnRev(Right);
  Wait(PanicTurnTime);

  Off(Right);
  SetPower(Left,MaxTurn);  // left motor reverse
  OnRev(Left);
  Wait(PanicTurnTime);

  SetPower(Left+Right,MaxTurn); // turn left
  OnFwd(Right);
  OnRev(Left);
  Wait(PanicTurnTime);

  SetPower(Left+Right,MaxFwd);  // and go forward
  OnFwd(Left+Right);

  ClearTimer(0);
}