Multi-Map-Navigation

This project extends Nav2 with the ability to navigate across multiple maps, using a custom action and a wormhole database. Compatible with ROS 2 Humble.

Package Overview

Anscer Navigation

This package contains codes to run the Nav2 System and the Multi-Map System. Multi-Map system uses BFS to find paths between maps that are not directly connected through a wormhole.

Purpose

• Navigate to goals that may exist in different maps.
• Handle map switching dynamically.
• Access wormhole connections between maps.
• Provide a custom action server (multi_map_navigate).

Action

# Goal
string target_map
float64 x
float64 y
float64 yaw
---
# Result
bool success
string message
---
# Feedback
string current_map

---

Anscer Slam

This package contains codes to run SLAM (slam_toolbox) and the Map Saver node which saves the map as well as wormhole coordinates straight into SQL DB through an exposed service.

Purpose

• Perform Mapping
• Automate storage of map details into a SQL DB

Service

# Request
string map_from
string map_to
string map_name
---
# Response
bool success
string message

---

Database (SQLITE)

Location: maps/multimap.db

Schema

CREATE TABLE wormhole (
  map_from TEXT,
  map_to   TEXT,
  x        REAL,
  y        REAL,
  yaw      REAL
);

Meaning

Each row defines a wormhole:

• map_from: Source map name
• map_to: Target map name
• (x, y, yaw): Pose of wormhole in the source map Each connection is bidirectional, so two entries are inserted.

---

Anscer Description

This package contains necessary URDF and Xacro files for simulation.

---

Anscer Teleop

This package contains custom WASD / Arrow key Teleop node.

---

Simulation PKG

This package contains launch files to run the simulation.

---

Steps to run

Database

sudo apt update
sudo apt install sqlite3

Build

rosdep install --from-paths src --ignore-src -r -y
colcon build --symlink-install

Note: Source every terminal hence forth

Run Simulation (Terminal 1)

ros2 launch simulation_pkg sim.launch.py

Run SLAM (Terminal 2) (Optional only if you want to make your own maps)

ros2 launch anscer_slam slam_launcher.launch.py

Run Wormhole Saver Service (Terminal 3) (Optional)

ros2 run anscer_slam wormhole_saver_service

Sample Call:

ros2 service call /save_wormhole anscer_slam/srv/SaveWormhole "{map_from: 'Hallway', map_to: 'Room1', map_name: 'Hallway_map'}"

Run Teleop (Terminal 4) (Optional)

ros2 run anscer_teleop teleop_node

Run Nav2 (Terminal 4) (only if teleop is not used)

ros2 launch anscer_navigation anscer_bringup.launch.py

Run Map Manager (Terminal 5)

ros2 run anscer_navigation multi_map_node

Sample Goal:

ros2 action send_goal /multi_map_navigate anscer_navigation/action/MultiMapNavigate "{target_map: 'Room1', x: 0.0, y: 0.0, yaw: 0.0}"

---

Program Flow

flowchart TD

subgraph SLAM_Map_Creation["SLAM & Map Saving"]
    A1[Run SLAM Toolbox / slam_toolbox] --> A2[Explore environment]
    A2 --> A3[Save map with map_saver]
    A3 --> A4[Generate map.yaml + map.pgm]
end

subgraph Database_Setup["Database Setup"]
    B1[Create SQLite multimap.db] --> B2[Insert wormhole entries]
    B2 --> B3[Each wormhole: from_map, to_map, x, y, yaw]
end

subgraph Localization["Localization & Odometry"]
    C1[AMCL Node] --> C2[Uses map + laser scan + odom]
    C2 --> C3[Publishes pose in map frame]
    C1 --> C4[Requires initial pose after map switch]
    C5[Odometry Source e.g. gazebo/odom] --> C2
end

subgraph MultiMap_Navigation["Multi-Map Navigation Node"]
    D1[User sends MultiMapNavigate Action Goal] --> D2{Is target map == current map?}

    D2 -- Yes --> D3[NavigateToPose Action Client] --> D4[Robot navigates to target pose] --> Z[Success]

    D2 -- No --> D5[Find Path via Wormholes in multimap.db]
    D5 -->|No path| D6[Abort: No wormhole path found]

    D5 -->|Path found| D7[Traverse wormhole sequence]
    D7 --> D8[Navigate to wormhole exit pose]
    D8 -->|Success| D9[Switch Map via LoadMap Service]
    D9 -->|Success| D10[Set AMCL initial pose for new map]
    D10 --> D11[Update current_map]
    D11 --> D7
    D7 -->|Last wormhole reached| D12[NavigateToPose to final goal]
    D12 --> Z[Success]
end

SLAM_Map_Creation --> Database_Setup
Database_Setup --> MultiMap_Navigation
Localization --> MultiMap_Navigation

Loading

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Known Issues

• Once Map Switches, Re-initialization of Map doesn't take place if you have created the new Room map in the same SLAM Session without resetting Odometry.
• Certain File Paths are Hardcoded.
• Launch File Creation Left to make it easier to use.