Topological Map Definition

Topological Map

A topological map in the strands system is published over the '/topological_map' topic its ros message is type defined the following way:

string name          # topological map name generally should be the same as in the pointset field
string map           # 2D Metric map name (not used currently)
string pointset      # The name of the group of nodes that compose the topological map, typically the same as name
string last_updated  # Last time the map was modified
strands_navigation_msgs/TopologicalNode[] nodes  # The group of nodes that composes the topological map

Topological Nodes

The nodes are the locations to which the robot should navigate on its working environment these location are related to coordinates in the robot map frame, the nodes are defined as a ros message in the following [way] (https://github.com/strands-project/strands_navigation/blob/indigo-devel/strands_navigation_msgs/msg/TopologicalNode.msg)

string name                 # Node name
string map                  # 2D Metric map name (not used currently)
string pointset             # The name of the group of nodes that compose the topological map
geometry_msgs/Pose pose     # Node X,Y,Z,W coordinates in the map frame
float64 yaw_goal_tolerance  # The tolerance in radians for the waypoint position
float64 xy_goal_tolerance   # The tolerance in meters for the waypoint position
Vertex[] verts              # X,Y coordinates for the vertices of the influence zone relative to the node pose
Edge[] edges                # The group of outward oriented edges connecting this node to others
string localise_by_topic    # The configuration for localisation by topic 

Edges

The edges are the definitions for the connections between nodes, typically this connections are included in the node message, which means that the edges defined for each node are the ones on which the node they are defined at is the point of origin, they are also defined as a ros message type in the following way

string edge_id                        # An identifier for the edge
string node                           # Name of destination node
string action                         # Name of navigation action, e.g. move_base
float64 top_vel                       # Maximum speed in [m/s]
string map_2d                         # Name of the 2D map 
float64 inflation_radius              # Obstacle inflation radius on this edge, 0 for default
string recovery_behaviours_config     # Not currently used, typically a json string

YAML format

the topological map can also be defined in yaml format, this is used to export and manually modify maps a map on this format would look like this:

- meta:
    map: mb_arena
    node: Start
    pointset: mb_test2
  node:
    edges:
    - action: move_base
      edge_id: Start_End
      inflation_radius: 0.0
      map_2d: mb_arena
      node: End
      recovery_behaviours_config: ''
      top_vel: 0.55
    localise_by_topic: ''
    map: mb_arena
    name: Start
    pointset: mb_test2
    pose:
      orientation:
        w: 0.92388
        x: 0
        y: 0
        z: 0.38268
      position:
        x: -1.5
        y: 2.6
        z: 0.0
    verts:
    - x: 0.689999997616
      y: 0.287000000477
    - x: 0.287000000477
      y: 0.689999997616
    - x: -0.287000000477
      y: 0.689999997616
    - x: -0.689999997616
      y: 0.287000000477
    - x: -0.689999997616
      y: -0.287000000477
    - x: -0.287000000477
      y: -0.689999997616
    - x: 0.287000000477
      y: -0.689999997616
    - x: 0.689999997616
      y: -0.287000000477
    xy_goal_tolerance: 0.3
    yaw_goal_tolerance: 0.1
- meta:
    map: mb_arena
    node: End
    pointset: mb_test2
  node:
    edges:
    - action: move_base
      edge_id: End_Start
      inflation_radius: 0.0
      map_2d: mb_arena
      node: Start
      recovery_behaviours_config: ''
      top_vel: 0.55
    localise_by_topic: ''
    map: mb_arena
    name: End
    pointset: mb_test2
    pose:
      orientation:
        w: 0.70711
        x: 0.0
        y: 0.0
        z: -0.70711
      position:
        x: -1.5
        y: -0.5
        z: 0.0
    verts:
    - x: 0.689999997616
      y: 0.287000000477
    - x: 0.287000000477
      y: 0.689999997616
    - x: -0.287000000477
      y: 0.689999997616
    - x: -0.689999997616
      y: 0.287000000477
    - x: -0.689999997616
      y: -0.287000000477
    - x: -0.287000000477
      y: -0.689999997616
    - x: 0.287000000477
      y: -0.689999997616
    - x: 0.689999997616
      y: -0.287000000477
    xy_goal_tolerance: 0.3
    yaw_goal_tolerance: 0.1

All the fields correspond to the definitions presented before, please note that each node has a "meta" field.

Node Meta information

Each node is stored in the datacentre with additional meta information, in the YAML version of a topological map this meta information MUST be included with at lest the three fields shown in the map, however any other meta information can be added as long as it is included in a valid YAML format for example:

- meta:
    map: mb_arena
    node: End
    pointset: mb_test2
    example: 'this is an example field'