PX4-GPS-Denied-Navigation-RTAB-Mapping

A complete simulation and SLAM stack for autonomous drone navigation in GPS-denied environments using PX4, ROS 2, RTAB-Map, and Gazebo Harmonic.

Table of Contents

• Overview
• Prerequisites
• 1. Setting Up Workspaces
• 2. PX4 Model Integration
• 3. Terminal Launch Breakdown
• 4. Bridging and Remapping Topics
• 5. RTAB-Map Launch (Terminal 10)
• 6. ENU to NED Conversion for PX4
• 7. Parameter Configuration for PX4
• 8. TF Tree Reference

Overview

This repository integrates the following:

• PX4 Autopilot SITL with a depth camera drone.
• ROS 2 Gazebo Harmonic with full RTAB-Map support
• Visual-Inertial Odometry pipeline with ENU to NED conversion for PX4
• Custom odometry bridge to PX4.
• ROS 2 TF publishing and RTAB-Map mapping stack
• Multi-terminal orchestration for GPS-denied SLAM navigation
• Shell script for launching all bridge nodes efficiently

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Prerequisites

Make sure you clone and build the following repositories:

• PX4-Autopilot
• px4_msgs
• rtabmap
• rtabmap_ros
• ros_gz_bridge

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1. Setting Up Workspaces

Clone the repo using:

cd ~/ros2_ws
mkdir -p src && cd src
git clone https://github.com/avianbob/PX4-GPS-Denied-Navigation-RTAB-Mapping.git

GPS_Denied_Navigation and odometry_converter

cd ~/ros2_ws
colcon build --packages-select GPS_Denied_Navigation odometry_converter
source install/setup.bash

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2. PX4 Model Integration

The model gz_x500_depth is used. Copy the model directory provided in this repo to:

rm -rf ~/PX4-Autopilot/Tools/simulation/gz/models/x500_depth
cp -r ~/ros2_ws/src/Model_Files/x500_depth ~/PX4-Autopilot/Tools/simulation/gz/models/

This ensures PX4 launches the model correctly with depth camera and odometry plugins.

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3. Terminal Launch Breakdown

You can use manual terminals or the provided shell script.

Navigate to the script folder:

cd ~/ros2_ws/src/GPS_Denied_Navigation/scripts
chmod +x all_terminals.sh
./all_terminals.sh

This launches 8 terminals automatically.

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Manual Terminal Plan

Terminal	Purpose
1	Run PX4 SITL: make px4_sitl gz_x500_depth
2	Run QGroundControl: ./QGroundControl.AppImage
3	Run MicroXRCEAgent: MicroXRCEAgent udp4 -p 8888
4–9	Run ros_gz_bridge for 6 essential topics (see below)
10	Run Odometry Converter Node (RTAB Odometry to PX4): python3 odom_to_px4_vision.py
11	Launch RTAB-Map: see below

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4. Bridging and Remapping Topics

Use ros_gz_bridge to map the following Gazebo topics to ROS 2:

Gazebo Topic	ROS 2 Topic
/clock	/clock
/world/<world>/model/x500_depth_0/link/camera_link/sensor/IMX214/image	/rgb/image
/world/<world>/model/x500_depth_0/link/camera_link/sensor/IMX214/camera_info	/rgb/camera_info
/depth_camera	/depth/image
/world/<world>/model/x500_depth_0/link/base_link/sensor/imu_sensor/imu	/imu
/model/x500_depth_0/odometry	/odom_px4

Replace <world> with your actual Gazebo world name.

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5. RTAB-Map Launch (Terminal 11)

ros2 launch GPS_Denied_Navigation depth_camera_simulation.launch.py \
  rgb_topic:=/rgb/image \
  camera_info_topic:=/rgb/camera_info \
  depth_topic:=/depth/image \
  odom_topic:=/odom_px4 \
  imu_topic:=/imu \
  use_sim_time:=true \
  subscribe_odom:=true \
  wait_imu_to_init:=true

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6. ENU to NED Conversion for PX4

Use the script odom_to_px4_vision.py to convert /odom (ENU) from RTAB-Map into /fmu/in/vehicle_visual_odometry (NED) for PX4.

To run:

cd ~/ros2_ws/src/GPS_Denied_Navigation/scripts
chmod +x odom_to_px4_vision.py
python3 odom_to_px4_vision.py

This ensures PX4 can use visual-inertial pose estimates for control.

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7. Parameter Configuration for PX4

Copy the PX4 parameters file from:

~/ros2_ws/src/GPS_Denied_Navigation/parameters.params

Load it into QGroundControl.

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8. TF Tree Reference

Refer to:

~/ros2_ws/src/GPS_Denied_Navigation/TF Tree.pdf

For understanding TF between base_link, camera, and imu.

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