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Subject: 
Re: NQC Code
Newsgroups: 
lugnet.robotics
Date: 
Wed, 9 Dec 1998 19:03:54 GMT
Original-From: 
John Donaldson <JDONALDSON@GHG.NETnomorespam>
Viewed: 
1430 times
  
Dave,

  Sorry for not getting back sooner. Been out of town. Anyway, thanks
for
the reply. This is what I am looking for. I am going to combine this
wirh another routine. Basicly

  1. Right Touch Sensor hits object.
   RCount += 1;
   IF RCount >= 2
   {
     RCount = 1;
   }

  2. Same for Left Touch Sensor

  IF RCount = 1 && LCount = 1
  // Stuck in Corner
  {
    RevMotor(AC);
    Sleep(500);
    FwdMotor(C);
    Sleep(500);
    Fwdmotor(A);
    RCount = 0;
    LCount = 0;
  }

  This way if one sensor countinues to hit then it is the same wall or
mabey a curved wall.
  If both sensors have a count of one (1) then means it first hit on
one side of the wall and then one the other side of the wall. With both
a count one (1), it reverses and the turns around.
  The timer function will also be used to backup the count by loking for
certain values too.

John D.



Dave Baum wrote:

In article <3665A4B9.861224B6@ghg.net>, lego-robotics@crynwr.com (John
Donaldson) wrote:

I got two questions.

1. How do you use the timer() function under NQC?
2. What is best way to determine if bot is stuck in corner make it turn
180 deg to get out?

John A. Donaldson

I'm going from memory here - sorry if I goof something up....

There are three timers (0, 1, and 2).  They are free running at 10Hz
(100ms per tick).  They do not run while the RCX is "off", but they do
retain their count.  You can clear a timer with ClearTimer(n), where n is
0, 1 or 2.  You an retrive the current timer value with Timer(n).

This can be a good way to repeat a certain series of steps for a certain
amount of time.  I've appended a sample program I used for a line follower
robot.  There's a loop in the follow() subroutine where the program turns
until it either hits a line or a timeout expires.

Dave

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

/* tracker.nqc
* written by Dave Baum for nqcc 0.5 b1
*
* This is a more complex program for a line-following robot.
* As usual, outputs A and C drive right and left tank treads,
* while input 1 is a light sensor at the front of the robot.
*
* The follow() subroutine follows a thin line until in
* encounters a very dark spot, at which point the robot
* stops.  When following a line, the robot runs forward
* until the light sensor reading exceeds a given value,
* at which point it starts turning right (or left) a bit
* looking for the rest of the line.  It continues to
* oscillate left and right until it finds the line, then
* continues forward.  The program remembers the direction
* previously used to find the line, so it can start turning
* the same way next time it loses the line.
*
* The main program follows a line until it reaches the end (a
* dark spot), then beeps, turns around, and follows the line
* back to the start.  The "test" surface should be white with
* a thin black line (1/8 inch thick) which can turn and curve
* as you desire.  Solid dark "endpoint" should be at both ends
* of the line - 1" wide black squares work well.
*
*/

#define EYE IN_1
#define LEFT   OUT_C
#define RIGHT  OUT_A

#define NORMAL_SPEED 6
#define TURN_SPEED 2
#define DELAY  20

#define CUTOFF 55
#define STOP   48

int direction, time, eye;

#define INITIAL_TIME 2

task main
{
   Sensor(EYE, IN_LIGHT);

   direction = 1;
   time = INITIAL_TIME;

   follow();
   PlaySound(5);

   turn_around();
   follow();
}

sub turn_around
{
   Fwd(LEFT, TURN_SPEED);
   Rev(RIGHT, TURN_SPEED);

   wait(EYE > CUTOFF);
   Sleep(25);
   wait(EYE < CUTOFF);

   Off(LEFT+RIGHT);
}

sub follow
{
   Fwd(LEFT+RIGHT, NORMAL_SPEED);
   while(true)
   {
      eye = EYE;
      if (eye < STOP) break;
      if (eye <= CUTOFF) continue;

      {
         ClearTimer(0);
         if (direction == 1)
         {
            Fwd(RIGHT, TURN_SPEED);
            Rev(LEFT, TURN_SPEED);
         }
         else
         {
            Fwd(LEFT, TURN_SPEED);
            Rev(RIGHT, TURN_SPEED);
         }

         while(true)
         {
            if (EYE < CUTOFF)
            {
               time = INITIAL_TIME;
               break;
            }

            if (Timer(0) > time)
            {
               direction *= -1;
               time *= 2;
               break;
            }
         }

         Fwd(RIGHT+LEFT, NORMAL_SPEED);
      }
   }

   Off(RIGHT+LEFT);
}

--
reply to: dbaum at enteract dot com



Message is in Reply To:
  Re: NQC Code
 
(...) I'm going from memory here - sorry if I goof something up.... There are three timers (0, 1, and 2). They are free running at 10Hz (100ms per tick). They do not run while the RCX is "off", but they do retain their count. You can clear a timer (...) (25 years ago, 3-Dec-98, to lugnet.robotics)

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