ros2_odometry_node

A ROS 2 node that publishes odometry for wheeled robots. The package currently focuses on mecanum drive support and converts wheel encoder ticks and wheel RPMs into /odom messages and a wheel_positions diagnostic topic. An Ackermann implementation stub is present for future expansion.

Features

• ROS 2 C++ node (ros2_odometry_node) built with rclcpp and ament_cmake.
• Mecanum drive implementation that subscribes to encoder and velocity arrays, computes pose/velocity, and publishes nav_msgs/Odometry.
• Launch file and parameter YAML for quick configuration.

Package layout

src/ros2_odometry_node/
├── config/odometry_params.yaml   # Default parameters for mecanum kinematics
├── launch/odometry.launch.py     # Launch file running the node with parameters
├── src/                          # Node implementation and drive-specific logic
├── header/                       # Internal headers for core and drive helpers
└── include/ros2_odometry_node/   # Public headers and interfaces

Building

This is a standard ROS 2 ament package. From your workspace root:

colcon build --packages-select ros2_odometry_node
source install/setup.bash

Ensure dependencies in package.xml (e.g., rclcpp, nav_msgs, tf2_ros) are available in your ROS 2 installation.

Running

Launch the node with the provided parameters:

ros2 launch ros2_odometry_node odometry.launch.py

The launch file loads config/odometry_params.yaml, which defaults to the mecanum drive type. You can override parameters on the command line, for example:

ros2 launch ros2_odometry_node odometry.launch.py \
  ros2_odometry_node.drive_type:=MECANUM \
  ros2_odometry_node.ticks_per_rev:=4200.0

Topics (mecanum)

• Subscribes: encoder1, encoder2, velocity1, velocity2 (std_msgs/Float32MultiArray, each with two wheel values).
• Publishes: /odom (nav_msgs/Odometry), wheel_positions (std_msgs/Float32MultiArray).

Parameters

Key parameters (see config/odometry_params.yaml):

• drive_type (string): Drive model to use. Default: "MECANUM".
• ticks_per_rev (double): Encoder ticks per revolution.
• wheel_radius (double): Wheel radius in meters.
• robot_l (double): Half-length of the robot footprint in meters.
• robot_w (double): Half-width of the robot footprint in meters.
• angle_epsilon (double): Threshold to treat rotational changes as zero.

You can edit config/odometry_params.yaml or override values via the command line when launching.

Notes

• The Ackermann implementation is currently a placeholder; the mecanum pipeline is the primary supported drive type.
• Publish encoder and wheel velocity arrays in the expected order so the node can compute accurate odometry.