This libary implements a discrete map use wich can be use in robotics. More...

Map constaints

#define	MAP_CELL_SIZE_MM 50
	Size of a cell in mm.
#define	MAP_CELL_SIZE_M (MAP_CELL_SIZE_MM/1000.0)
	Size of a cell in mm.
#define	MAP_WIDTH (PLAYGROUND_WIDTH_MM / MAP_CELL_SIZE_MM)
	Field width.
#define	MAP_HEIGHT (PLAYGROUND_HEIGHT_MM / MAP_CELL_SIZE_MM)
	Field height.
#define	MAP_PLAYGROUND_WIDTH_MM (MAP_WIDTH*MAP_CELL_SIZE_MM)
	Playground width depends on width and cell size.
#define	MAP_PLAYGROUND_WIDTH_M (MAP_PLAYGROUND_WIDTH_MM/1000.0)
	Size of a cell in mm.
#define	MAP_PLAYGROUND_HEIGHT_MM (MAP_HEIGHT*MAP_CELL_SIZE_MM)
	Playground width depends on height and cell size.
#define	MAP_PLAYGROUND_HEIGHT_M (MAP_PLAYGROUND_HEIGHT_MM/1000.0)
	Size of a cell in mm.
Cell Flags

#define	MAP_FLAG_WALL 1
	Known wall.
#define	MAP_FLAG_PATH 2
	Known wall.
#define	MAP_FLAG_START 4
	Known wall.
#define	MAP_FLAG_GOAL 8
	Known wall.
#define	MAP_FLAG_DET_OBST 16
	Set when an obstacle is detected, cleard on every "map forget cycle".
#define	MAP_FLAG_SIMULATED_WALL 32
	Used by robomon to simulate obstacles.
#define	MAP_FLAG_IGNORE_OBST 64
	If obstacle is detected here, ignore it.
#define	MAP_FLAG_PLAN_MARGIN 128
	"Safety margin" around obstacle - used only during A* planning and not during runtime obstacle avoidance.
#define	MAP_FLAG_INVALIDATE_WALL 256
	Area, where the wall should be forgotten.
Shared Memory macros

#define	SHM_MAP_KEY 555
	Key use to share the memory SHM.

Detailed Description

This libary implements a discrete map use wich can be use in robotics.

The features are:

Shared map memory (Shared Memory Map) : the map memory is shared using interprocess comunication methods.
Discrete Space (The discrete Map): the real space is divided into cells of variable size. Each cell has its own properties.

Shared Memory Map

There are two important methods to access the shared map. Before using shmap, it should be init by the function ShmapInit(). After finishing using it the shmap should be clear by ShmapFree().

Warning:: If the program exit without a ShmapFree(), the memory will stay in Linux SHM. You can verify it with command "ipcs -m". For further details, read shm documentation.

The map

The real space

The map size is (MAP_PLAYGROUND_WIDTH_MM x MAP_PLAYGROUND_HEIGHT_MM). This space discretization is explained in section The discrete Map .

                                0                                       MAP_PLAYGROUND_WIDTH_MM
 MAP_PLAYGROUND_HEIGHT_MM       +---------------------------------------+
                                |                                       |
                                |                                       |
                                |                                       |
                                |                                       |
                                |                                       |
                                |                                       |
                                |                                       |
                                |                                       |
                                |                                       |
                                |                                       |
                                |                                       |
                                |                                       |
                                |                                       |
                                |                                       |
                                |                                       |
                           y=0  +---------------------------------------+ 0
                               x=0                                      MAP_PLAYGROUND_WIDTH_MM

The discrete Map

Map library uses a discrete representation of the space. This representation has been implemented as a cell grid (matrix). Each cell (pixel) is represents MAP_CELL_SIZE mm square. We can consider a cell as a set of points. All the points of a cell have the same value that the cell. The origin is located in up left corner.

There are only a coordonates difference between points and cells. Cell which cordonates [0,0] represents all the points contained in a square sited up left corner.

                                X 0   1   2   3   4   5   6   7   8   MAP_WIDTH-1
                              Y +---+---+---+---+---+---+---+---+---+---+
                              0 |0,0|   |   |   |   |   |   |   |   |   |
                                +---+---+---+---+---+---+---+---+---+---+
                              1 |   |   |   |   |   |   |   |   |   |   |
                                +---+---+---+---+---+---+---+---+---+---+
                                |   |   |   |   |   |   |   |   |   |   |
                                +---+---+---+---+---+---+---+---+---+---+
                                |   |   |   |   |   |   |   |   |   |   |
                                +---+---+---+---+---+---+---+---+---+---+
                                |   |   |   |   |   |   |   |   |   |   |
                                +---+---+---+---+---+---+---+---+---+---+
                                |   |   |   |   |   |   |   |   |   |   |
                                +---+---+---+---+---+---+---+---+---+---+
                                |   |   |   |   |   |   |   |   |   |   |
                                +---+---+---+---+---+---+---+---+---+---+
                                |   |   |   |   |   |   |   |   |   |   |
                                +---+---+---+---+---+---+---+---+---+---+
                                MAP_HEIGHT-1

Note:: Matrix convention is usally (row, column). In this program the convention will be (column, row) in order to keep real coordonates relation. C language stockes matrix in rows, so a cell coordonate (x,y) will be in a C matrix [y][x].

Map Content

Each cell/point of the map (MapCell) contains two types of information:

Value (MapCellValue) : It determins the type of cell. It is the information used by A* algorithm.
Flag (MapCellFlag) : It is extra information.

Map Values

This information is of the type MapCellValue.The value that the map contains can be:

MAP_WALL: Wall of the map. A fixed obstacle.
MAP_WALL_CSPACE : Configuration Space of a wall.
MAP_PATH: A part of path.
MAP_START: The Start
MAP_GOAL: The Goal
MAP_NEW_OBSTACLE: New obstacle. This type is set when the sensors found an obstacle. It can be view as a moving obstacle.
MAP_NEW_OBSTACLE_CSPACE: Configuration Space of the obstacle .
MAP_FREE: Free space.

One special type is MAP_NOT_IN_MAP. It is a error code return when we try to acces to a space wich is not in the map. (i.e. the request cell/point exceeds map dimensions.)

Note:: The configuration space is a special obstacle type that depends on the geometry of the robot. For more information, read a book about robotics.

Cell Flags

The possible cell flags are:

One special type is MAP_FLAG_ERROR. It is a error code return when we try to acces to a space wich is not in the map. (i.e. the request cell/point exceeds map dimensions.)

Accessing to map information

FIXME: Obsolete: ShmapGetPointValue(), ShmapSetPointValue(), ShmapSetPointValue(), ShmapSetCellValue() do not exist

To read and write cell values, use functions ShmapGetCellValue() and ShmapSetCellValue(). If you want to acces directly to points, you can also use ShmapGetPointValue() and ShmapSetPointValue().

There are similar functions to get and set flags: ShmapGetCellFlag() and ShmapSetCellFlag(), ShmapGetPointValue() and ShmapSetPointFlag().

It can be possible also to edit more than a point at the same time with function ShmapSetRectangleType().

If you want to know if a cell is free see ShmapIsFreeCell() and ShmapIsFreePoint().

ShmapUpdateTmpObstacles() is a specific function created for Eurobot Project. Please, see an example in testmap.c file

Define Documentation

#define MAP_CELL_SIZE_M (MAP_CELL_SIZE_MM/1000.0)

Size of a cell in mm.

The cell is a square.

#define MAP_CELL_SIZE_MM 50

Size of a cell in mm.

The cell is a square.

#define MAP_FLAG_DET_OBST 16

Set when an obstacle is detected, cleard on every "map forget cycle".

Examples:: testmap.c.

#define MAP_FLAG_GOAL 8

Known wall.

#define MAP_FLAG_IGNORE_OBST 64

If obstacle is detected here, ignore it.

#define MAP_FLAG_INVALIDATE_WALL 256

Area, where the wall should be forgotten.

#define MAP_FLAG_PATH 2

Known wall.

#define MAP_FLAG_PLAN_MARGIN 128

"Safety margin" around obstacle - used only during A* planning and not during runtime obstacle avoidance.

#define MAP_FLAG_SIMULATED_WALL 32

Used by robomon to simulate obstacles.

#define MAP_FLAG_START 4

Known wall.

#define MAP_FLAG_WALL 1

Known wall.

Examples:: testmap.c.

#define MAP_HEIGHT (PLAYGROUND_HEIGHT_MM / MAP_CELL_SIZE_MM)

Field height.

#define MAP_PLAYGROUND_HEIGHT_M (MAP_PLAYGROUND_HEIGHT_MM/1000.0)

Size of a cell in mm.

The cell is a square.

#define MAP_PLAYGROUND_HEIGHT_MM (MAP_HEIGHT*MAP_CELL_SIZE_MM)

Playground width depends on height and cell size.

#define MAP_PLAYGROUND_WIDTH_M (MAP_PLAYGROUND_WIDTH_MM/1000.0)

Size of a cell in mm.

The cell is a square.

#define MAP_PLAYGROUND_WIDTH_MM (MAP_WIDTH*MAP_CELL_SIZE_MM)

Playground width depends on width and cell size.

#define MAP_WIDTH (PLAYGROUND_WIDTH_MM / MAP_CELL_SIZE_MM)

Field width.

#define SHM_MAP_KEY 555

Key use to share the memory SHM.

Library to manage the map

Map constaints

Cell Flags

Shared Memory macros

Detailed Description

Shared Memory Map

The map

The real space

The discrete Map

Map Content

Map Values

Cell Flags

Accessing to map information

Define Documentation