emcl2_ros2: mcl with expansion resetting (version 2)

Emcl is an alternative Monte Carlo localization (MCL) package to amcl (http://wiki.ros.org/amcl). Differently from amcl, KLD-sampling and adaptive MCL are not implemented. Instead, the expansion resetting and other features are implemented¹².

This package is ROS 2 version of ryuichiueda/emcl2.

ROS 2 version

• ROS 2 Humble Hawksbill

quick start

Install & Build

mkdir ros2_ws && cd ros2_ws
git clone git@github.com:CIT-Autonomous-Robot-Lab/emcl2_ros2.git ./src/emcl2_ros2
rosdep update
rosdep install -y --from-paths src --ignore-src --rosdistro $ROS_DISTRO
sudo apt install -y ros-$ROS_DISTRO-navigation2 ros-$ROS_DISTRO-nav2-bringup ros-$ROS_DISTRO-turtlebot3-gazebo
colcon build --symlink-install --cmake-args -DCMAKE_BUILD_TYPE=Release
source install/setup.bash

Try emcl2 in simulator

You may wait Gazebo to be initilalized. You can also use ./test/demo.bash, in which the following procedure is written.

export TURTLEBOT3_MODEL=burger
ros2 launch turtlebot3_gazebo turtlebot3_world.launch.py
ros2 launch nav2_bringup rviz_launch.py
ros2 launch emcl2 emcl2.launch.py params_file:=$(ros2 pkg prefix --share emcl2)/config/emcl2_quick_start.param.yaml map:=$(ros2 pkg prefix --share nav2_bringup)/maps/turtlebot3_world.yaml use_sim_time:=true
ros2 launch nav2_bringup navigation_launch.py use_sim_time:=true

demo movies

Nodes

emcl2_node

This node calculates the alpha value with a different algorithm than emcl_node in ryuichiueda/emcl. This node counts the particles that make lasers penetrate occupancy cells. Specifically, this node chooses some particles at a rate of extraction_rate and checks each of them with the following procedure:

• maps a set of laser scan on the occupancy grid map based on the pose of the particle
• judges the pose of the particle as wrong if all of lasers in a range_threshold[rad] range penatrate occupancy grids

If the rate of the wrong particles is greater than alpha_threshold, the node invokes a reset.

This node also has a sensor resetting algorithm. When sensor_reset is true, a particle with laser penetration is dragged back from occupied cells.

Subscribed Topics

Published Topics

Parameters

The followings have never been implemented yet.

To do

• Implement service
• Fix a bug that caused particles to survive

citation