Thread: Help! Robot Programming

Hey, im doing my first programming subject and i really need help with an assignment.

I have to write a simulator program for a robot designed to move packages around in a warehouse environment.

The map specifies the size, shape and initial positions of all the packages in the environment, as well as the positions of the walls, and the initial position and orientation of the robot. The walls will be represented by the "star" character *. The robot will be represented by the characters ^, v, < or >, depending on which direction it is facing.

I can only give the robot 4 commands:
L turn left
R turn right
F (try to) move forward
P print the state of the environment

When it executes an L or R instruction, the robot remains in the same location and only its orientation changes. When it executes the F instruction, the robot attempts to move a single step in whichever direction it is facing.


Right now i can get the robot to scan the environment and print out what it sees. But i can't get my robot to move.. can anyone give me any pointers??

heres the code i have so far.

Code:

#include <stdio.h>

#define ROBOT       26
#define WALL        27
#define NONE        -1

#define MAX_ROWS    80
#define MAX_COLS    80

#define EAST         0
#define NORTH        1
#define WEST         2
#define SOUTH        3

void scan_state(
                 int *pnrows,
                 int  ncols[MAX_ROWS],
                 int  object[MAX_ROWS][MAX_COLS],
                 int *pdirection
	       );

void print_state(
                 int nrows,
                 int ncols[MAX_ROWS],
                 int object[MAX_ROWS][MAX_COLS],
                 int direction
	        );

int main( void )
{
  int nrows;                      // number of rows in environment
  int ncols[MAX_ROWS];            // number of columns in each row
  int object[MAX_ROWS][MAX_COLS]; // object at each location
  int direction;                  // which way the robot is facing

  // scan the state of the environment
  scan_state( &nrows, ncols, object,&direction );

  // print the state of the environment
  print_state( nrows, ncols, object, direction );

  return 0;
}

void scan_state(
                 int *pnrows,
                 int  ncols[MAX_ROWS],
                 int object[MAX_ROWS][MAX_COLS],
                 int *pdirection
               )
{
  int ch;
  int r,c,rr,rc;

  r = 0;
  c = -1;

  while (( ch = getchar() ) != '(' ) {
    c++;
    if ( ch == '\n' ) {
      ncols[r++] = c;
      c = -1;
    }
    else if ( ch == '*' ) {
      object[r][c] = WALL;
    }
    else if ((ch >='A' )&&( ch <= 'Z')){
       object [r][c]= ch - 'A';  
    }
    else if ( ch == '^' ) {
      object [r][c] = ROBOT;
      *pdirection = NORTH;
    }
    else if ( ch == '>' ) {
      object [r][c] = ROBOT;
      *pdirection = EAST;
    }
    else if ( ch == 'v' ) {
      object [r][c] = ROBOT;
      *pdirection = SOUTH;
    }
    else if ( ch == '<' ) {
      object [r][c] = ROBOT;
      *pdirection = WEST;
    }
    else {
      object [r][c] = NONE;
    }
  }
  
  //give the robot its own cordinates.
  if (object[r][c] == ROBOT ) {
  object[rr][rc] = ROBOT;
  }
  
  while (( ch = getchar() ) != ')' ) {
    c++;
    if ( ch == '\n' ) {
      ncols[r++] = c;
      c = -1;
    }
    else if ( ch == 'L' ) {
      if ( *pdirection == SOUTH ) {
          *pdirection = EAST;
      }
      else {
        *pdirection++;
      }
    }
    else if (ch == 'R' ) {
      if ( *pdirection == EAST ) {
           *pdirection = SOUTH;
      }
      else {
        *pdirection--;
      }
    }
  }

 *pnrows = r;
}


void print_state(
                 int nrows,
                 int ncols[MAX_ROWS],
                 int object[MAX_ROWS][MAX_COLS],
                 int direction
                )
{
int r,c;

for( r=0; r < nrows ; r++ ) {
   for( c=0; c < ncols[r]; c++ ) {
      if (object[r][c] == WALL) {
      printf( "*" );
      }
      if (object[r][c] == NONE) {
      printf( " " );
      }
      if ((object [r][c]>= 0)&&(object [r][c]<= 25)){
         printf("%c",'A'+object [r][c]);
      }

      if ( object[r][c] == ROBOT ) {
        if (direction == NORTH) {
          printf("^");
        }
        if (direction == EAST) {
          printf(">");
        }
        if (direction == SOUTH) {
          printf("v");
        }
        if (direction == WEST) {
          printf("<");
        }
      }

   }
   printf( "\n" );
}


}

Thanks a lot.. i know its a crapload to read but any help is appreciated..

cheers

i echo quazah's response, but try using a function to move the robot based on a condition.

Code:

// if  ( robot has checked area NORTH ->(then) MOVE SOUTH ) 
{
    // pass a pointer to a new function perhaps?
}

EDIT: I thought homework questions were prohibited from the boards anyway

Ah! I see you're the same robot poster we had, before!

Well, I guess we can't have a determined poster go unrewarded. I'm now onto the computer with my C on it, so I'll take a look at your program, in more detail, today.

I'm looking at the environment in the robot.txt file, and I'm just wondering if the top of the robot's environment should be flat, or sloped with an opening on the left upper corner. I couldn't view it in notepad, so I'm using Wordpad to see it. Is that correct?

I'll post back later today when the din dies down for Wednesday.

You know this program is a lot like the game of "Sokoban". I had forgotten that game.

One question for you. The robot can push one box. Can he push a box which has been pushed up against another box (but not against a wall)?


Adak

Gizzle:

OK, if you're still working with this program, and since you "showed me yours", I'll "show you mine".

I won't deal with large re-writes of the code you posted up, because it's just against my religion to wade through someone else's code with superflous stuff, which I strongly suspect you didn't write, and don't fully understand, either.

So, let's start with something new and to the point. This isn't a full program, but it will become one, although perhaps slightly different than your assignment. Very close, though.

Code:

# include <stdio.h>

int cd, cp; /* cd=current direction, cp= current position */

int main(void)  {
   char move;
   int i, quit;
   GetEnv();                    /* get the set up environment */

   do  {                           /* start the "game' loop */
     PrintEnv();                /* print current environment */
     move = GetMove();   /* get the move or q to quit, and bring it back here */
     MakeMove(move);    /* definitely our trickiest function, imo */
   }while( move != 'q');  /* our "game" loop end */

   return 0;
}

MakeMove may need to be broken up into sub-functions, because it does so much. Pseudocode for a portion of it, is next

I'm going to break thus up into a few posts at least, so you have time to read and ask any questions.

Adak

Firstly i truly appreciate your help Adak, thanks mate.

I understand what you are doing, your code has a few more functions than mine with functions for getting environment and the instructions, and printing them out respectively.

Btw i did write up that code.

I've been working on it and i can make my robot turn left and right now. I used a crapload of IF statements. Ill show you what i did to make it turn.. but my if statements for moving forward don't relaly work.

Code:

  
  //Give the robot its own cordinates.
  if (object[r][c] == ROBOT ) {
  r_r=r;
  r_c=c;
  }

  while (( ch = getchar() ) != ')' ) {
    c++;
    if ( ch == '\n' ) {
      ncols[r++] = c;
      c = -1;
    }
    if ( ch == 'L' ) {
      if ( *pdirection == EAST ) {
          *pdirection = NORTH;
      }
      else if ( *pdirection == NORTH ) {
          *pdirection = WEST;
      }
      else if ( *pdirection == WEST ) {
          *pdirection = SOUTH;
      }
      else if ( *pdirection == SOUTH ) {
          *pdirection = EAST;
      }
    }
    if (ch == 'R' ) {
      if ( *pdirection == EAST ) {
           *pdirection = SOUTH;
      }
      else if ( *pdirection == SOUTH ) {
           *pdirection = WEST;
      }
      else if ( *pdirection == WEST ) {
           *pdirection = NORTH;
      }
      else if ( *pdirection == NORTH ) {
           *pdirection = EAST;
      }
    }
    if (ch == 'F' ) {
      if ( *pdirection == EAST ) {
        object[r_r+1][r_c] = ROBOT;

      }
      if ( *pdirection == SOUTH ) {
        object[r_r][r_c-1] = ROBOT;

      }
      if ( *pdirection == WEST ) {
        object[r_r-1][r_c] = ROBOT;

      }
      if ( *pdirection == NORTH ) {
        object[r_r][r_c+1] = ROBOT;

      }
    }

  }

I'm not too sure what im doing wrong. But something gives me the idea that its got to do with the beginning of my scan_state function when i did

Code:

  r = 0;
  c = -1;

Would this have forced my point to be fixed..? I'm not sure..

Thanks heaps.

The whole NORTH SOUTH EAST WEST thing is where I knew I'd need to write my own code.

IIRC, the instructions for the robot will be Left or Right, and Forward - and Print, and that's ALL. No directions, so why add them in?

On the robot environment, I'd ALWAYS use a centered area, like so:
0 1 2 3 4 5 6 7 8 9 A B
=================
9 9 9 9 9 9 9 9 9 9 9 9
9 0 0 0 0 0 0 0 0 0 0 9
9 0 ^ 0 B B B 0 0 0 0 9
9 0 0 A A 0 0 0 0 0 0 9
9 0 0 A A 0 0 0 0 0 0 9
9 9 9 9 9 9 9 9 9 9 9 9

So the #9 gives you a border you can detect easily, and your robot goes on columns 1 through 10 or 1 thru 80 in your case. (the 9 could be any value you like, clearly).

In your program, be sure you have your array set up and printing correctly before moving onto move. Otherwise it will be far more difficult to finish the program, imo.

I would start with a small array, as small as practical - just enough to see that the array is loading right, displaying right, and then we'll start on the moving.

More later,

Adak

Originally Posted by quzah

They're not there for the robot necessarily. They're there so you the programmer can plot through it easily. Foreward relative to what? What coordinate am I supposed to be incrementing or decrementing here? That's why we use compass directions. Because they're easy to map to a grid and for movement. The robot doesn't need to know anything about the directions.


Quzah.

You're NOT a Sokoban player!!

You can work DIRECTLY with the input from the user, and every movement is relative to the current position of the robot, of course.

Perhaps I'm too compass oriented, but on my screen, West is on my right hand side, but using these robot directions, West would have to be East, and of course, East would have to be West.

That doesn't HELP!

Adak