GNSS_Localizer

中文版本

This project generates /gnss_pose from GNSS/NMEA data, transforms it into the map frame, and can be integrated with modules such as ndt_matching.

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Introduction

1. nmea2tfpose

• Subscribes: /nmea_sentence (from serial GNSS receiver)
• Publishes: /gnss_pose (geometry_msgs/PoseStamped, frame = map)
• Key modifications:
  • Supports GNRMC messages and integrates yaw_ (heading).
  • Supports plane selection (Plane 13 = NTUT Ningxin Park in Taipei).

2. fix2tfpose

• Subscribes: /fix (sensor_msgs/NavSatFix)
• Publishes: /gnss_pose
• Function: Converts GNSS Fix directly into pose in the map frame.

3. geo_pos_conv

Converts latitude/longitude (WGS84) → local Cartesian coordinates (x,y,z).

• geo_pos_conv_SPIE.cpp

  • Implements the complete Transverse Mercator projection (rigorous mathematical formulas for converting from the Earth ellipsoid to a planar Cartesian coordinate system).
  • High accuracy, suitable for large-area use.

• geo_pos_conv_mydicoor.cpp

  • Uses a linear approximation:

    m_x = (m_lat - m_PLato) * 110773.52...
    m_y = (m_lon - m_PLo) * 100914.35...
    m_z = 0

  • Suitable for small local areas (e.g., campus/test field), with lower computation cost.
  • Limitation: Errors increase with distance from the origin.

Recommendation:

• Large-scale, multi-location tests → use SPIE
• Small-area quick demos → mydicoor is sufficient

RQT Graph

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Development Environment

• CMake 3.10+
• C++17 compiler
• (For ROS1 build) roscpp, sensor_msgs, geometry_msgs, tf, nmea_msgs

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Installation / Usage Examples

⚠️ Note: Please rename the corresponding CMakeLists.*.txt file to CMakeLists.txt before building.

ROS (catkin)

mv CMakeLists.catkin.txt CMakeLists.txt       # rename
# package.xml must also be placed in the root directory
cd ~/catkin_ws/src
ln -s /path/to/GNSS-Localizer .
cd ..
catkin_make
source devel/setup.bash
rosrun gnss_localizer nmea2tfpose

CMake (Only for Demo)

mv CMakeLists.cmake.txt CMakeLists.txt   # rename
mkdir -p build && cd build
cmake ..
make -j
./gnss_localizer

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Integration with Autoware

• Setup steps

  1. Launch the Serial GNSS node that publishes /nmea_sentence.
  2. Launch the nmea2tfpose node with parameter plane: 13 (Ningxin Park).
  3. In ndt_matching:
     • Set the initial pose (initial_pos) to gnss.
     • Adjust the fitness_score threshold to 1.0 (default 500 is not suitable for RTK-GPS precision).
  4. Use rqt_tf_tree to verify the TF structure.

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Project Structure

GNSS-Localizer/
├── .gitattributes
├── .gitignore
├── LICENSE
├── CMakeLists.catkin.txt
├── CMakeLists.cmake.txt
├── package.xml
├── images
│   └── rqt_graph.png
├── gnss/
│   ├── geo_pos_conv_mydicoor.cpp    # Simplified local coordinate conversion
│   └── geo_pos_conv_SPIE.cpp        # Accurate projection-based conversion
└── gnss_localizer/
    ├── fix2tfpose/
    │   └── fix2tfpose.cpp           # GNSS Fix → TF Pose
    └── nmea2tfpose/
        └── nmea2tfpose_core_SPIE.cpp # NMEA Sentence → Pose

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License and Acknowledgment

• MIT License
• Autoware