Path Planner

Please see path_planner() documentation, the main funtion of the library. More...

Functions
int	path_planner (double xstart_real, double ystart_real, double xgoal_real, double ygoal_real, PathPoint **simple_path, double *angle)
	Returns the number of points of the path on success or an error code.
void	freePathMemory (PathPoint *simple_path)
	Free memory allocated for simple path.
#define	DBG   printf
	Returns the number of points of the path on success or an error code.
#define	WALL_COST   1000
	Cost fo jumping a wall.
#define	MAP_WALL   0xFF
	Wall cell.
#define	MAP_PATH   0xFE
	Path cell.
#define	MAP_START   0xFD
	Start cell.
#define	MAP_GOAL   0xFC
	Goal cell.
#define	MAP_NEW_OBSTACLE   0xFB
	Fouded obstacle cell.
#define	MAP_FREE   0x00
	Free cell.
#define	SHM_MAP_KEY   555
	Key use to share the memory SHM.
#define	GETMAPPOS(i, j)   (*(map+i+j*MAP_WIDTH))
	Cost fo jumping a wall.
typedef unsigned char	map_t
	Cost fo jumping a wall.
Path Planner Error Codes
#define	PP_ERROR_MAP_NOT_INIT   -1
#define	PP_ERROR_GOAL_IS_OBSTACLE   -2
#define	PP_ERROR_GOAL_NOT_REACHABLE   -3

---

Detailed Description

Please see path_planner() documentation, the main funtion of the library.

For working it needs map library . Is not necessary to use other functions of the library. However if you are interested, please read Path planer internal functions

The internal algorithms

The program use an implementation of A* algorithm, aalgorithm() and simplifies it by path_simplifier().

An exemple of using this function:

 int main(){
        PathPoint * path;       // A pointer to the path
        PathPoint * tmp;        // A tmp pointer
        double angle;           // The angle of the final line
        double startx, starty, goalx, goaly;
 
        ShmapInit();    //Init shared map memory
 
        // Start and goal points of the path
        startx= 1.1; stary=1.1;
        goalx= 2.2; goaly = 2.0;
 
        //Calc the path
        if (path_planner(startx, starty, goalx, goaly, &path, &angle)) 
                printf("Path ok!\n");
        else    {
                printf("The planner can not reach the goal\n");
                return 0;
        }
 
        // Print the points of the trajectory
        tmp = path;
        printf("The points of the trajectory are: ");
        while (tmp!= NULL) {
                printf("(%f, %f) ", tmp->x, tmp->y);
                tmp = tmp->next;
        }
        printf("\n");
        printf("The final angle is : %f\n", angle);
        
        //Memory deallocation
        freePathMemory(path);   // Do not forget to free the path memory after use.

        ShmapFree();            //Free Shared Map Memory
 
        return 0;
 }

---

Define Documentation

#define DBG   printf

Returns the number of points of the path on success or an error code.

Parameters:

	xstart_real	X coordinate in meters
	ystart_real	Y coordinate in meters
	xgoal_real	X coordinate in meters
	ygoal_real	Y coordinate in meters
	simple_path	A pointer to where the simple path will be stocked
	angle	A pointer to a double variable where the final angle of the trajectory will be stocked.

Returns:

1 if a path is founded, 0 if not

Warning:

The Shared Map Memory must be init before.

Do not forget to free allocated memory with freePathMemory().

It takes parameters of start and goal points. It returns the number of points of the trajectory and the caller must specify pointers to path and angle.

The result of the algorithm is stored in a list of PathPoint, terminated by NULL, containing the points of the path. This memory is allocated dynamicaly and its address will be returned as a double pointer to the path (simple_path) passed as argument. After use the path, memory should be free with freePathMemory(). A pointer of the final angle must be also passed as argument.

The map memory must be init with ShmapInit() before calling path_planner(). Do not forget to free this map memory with ShmapFree().

#define GETMAPPOS	(		i,
			j
	)			(*(map+i+j*MAP_WIDTH))

Cost fo jumping a wall.

#define MAP_FREE   0x00

Free cell.

The robot can move on. White in robomon.

#define MAP_GOAL   0xFC

Goal cell.

Green in robomon.

#define MAP_NEW_OBSTACLE   0xFB

Fouded obstacle cell.

Blue in robomon.

#define MAP_PATH   0xFE

Path cell.

Darkred in robomon.

#define MAP_START   0xFD

Start cell.

Red in robomon.

#define MAP_WALL   0xFF

Wall cell.

Black in robomon.

#define PP_ERROR_GOAL_IS_OBSTACLE   -2

#define PP_ERROR_GOAL_NOT_REACHABLE   -3

#define PP_ERROR_MAP_NOT_INIT   -1

#define SHM_MAP_KEY   555

Key use to share the memory SHM.

#define WALL_COST   1000

Cost fo jumping a wall.

---

Typedef Documentation

typedef unsigned char map_t

Cost fo jumping a wall.

---

Function Documentation

void freePathMemory

(

PathPoint *

simple_path

)

Free memory allocated for simple path.

Parameters:

simple_path

A pointer to the list of points of simplest path

int path_planner	(	double	xstart_real,
		double	ystart_real,
		double	xgoal_real,
		double	ygoal_real,
		PathPoint **	simple_path,
		double *	angle
	)

Returns the number of points of the path on success or an error code.

Parameters:

	xstart_real	X coordinate in meters
	ystart_real	Y coordinate in meters
	xgoal_real	X coordinate in meters
	ygoal_real	Y coordinate in meters
	simple_path	A pointer to where the simple path will be stocked
	angle	A pointer to a double variable where the final angle of the trajectory will be stocked.

Returns:

1 if a path is founded, 0 if not

Warning:

The Shared Map Memory must be init before.

Do not forget to free allocated memory with freePathMemory().

It takes parameters of start and goal points. It returns the number of points of the trajectory and the caller must specify pointers to path and angle.

The result of the algorithm is stored in a list of PathPoint, terminated by NULL, containing the points of the path. This memory is allocated dynamicaly and its address will be returned as a double pointer to the path (simple_path) passed as argument. After use the path, memory should be free with freePathMemory(). A pointer of the final angle must be also passed as argument.

The map memory must be init with ShmapInit() before calling path_planner(). Do not forget to free this map memory with ShmapFree().

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