Flex Nav Turtlebot3 Demo

Introduction

Custom behaviors and launch files for demonstrations of the ROS 2 and FlexBE-based Flexible Navigation (Wiki) for use with the ROBOTIS-based Turtlebot.

This repository contains code that interfaces with the ROS 2 versions of the ROBOTIS Turtlebot3 models, the FlexBE Behavior Engine, FlexBE App, and the Flexible Navigation system.

Installation and Setup

This package has a number of dependencies.

The quickest and easiest method to get a demonstration up and running is to follow the instructions below.

1. Ensure that you are running a recent ROS 2 version

• This system is tested on ros-humble-desktop on Ubuntu 22.04
• See ROS 2 Installation for more information.
• Make sure the colcon build and rosdep tools are installed

2. The ROBOTIS Turtlebot3 packages (standard ROS install) are required

• You may install manually or depend on rosdep

3. Clone the required repositories into a ROS 2 workspace

• This repo

• FlexBE App

• FlexBE Behavior Engine

• Flexible Navigation

  NOTE: If official ROS 2 release versions are available, then you may use those. As of this update, they are NOT yet available for apt install.

NOTE: If you are using the ROS wstools, you may add the following to your .rosinstall file, and then do wstool merge and wstool update.

 - git: {local-name: src/flexbe_app,               uri: 'https://github.com/FlexBE/flexbe_app.git',                version: ros2-devel }
 - git: {local-name: src/flexible_navigation,      uri: 'https://github.com/FlexBE/flexible_navigation.git',       version: ros2-devel }
 - git: {local-name: src/flexbe_behavior_engine,   uri: 'https://github.com/FlexBE/flexbe_behavior_engine.git',    version: ros2-devel }
 - git: {local-name: src/flex_nav_turtlebot3_demo, uri: 'https://github.com/FlexBE/flex_nav_turtlebot3_demo.git',  version: ros2-devel }

NOTE: These repo branches are currently listed as the latest official development branches.

4. Install any required dependencies.

   rosdep update
   rosdep install -r --from-paths . --ignore-src

5. Build your workspace:

   colcon build

6. Install required nwjs binaries for FlexBE

   After building with colcon and sourcing the new setup.bash as normally required, you must download the required nwjs binaries before you can run the FlexBE App:

   ros2 run flexbe_app nwjs_install

Note: These are installed in the install folder. If the install folder is deleted, then the nwjs binaries will need to be reinstalled with this script.

Operation

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NOTE: An earlier release of Humble had an issue with Navigation 2 that resulted in an empty local costmap. This issue seems to be resolved; at the time, a fix was to change the default DDS provider

  # Dealing with https://github.com/ros-planning/navigation2/issues/3014 (2489 and 3018)
  echo "Changing default DDS to Cyclone due to Nav 2 issue!"
  export RMW_IMPLEMENTATION=rmw_cyclonedds_cpp

The following directions are for a simple demonstration of Flexible Navigation using ROS 2 Cartographer as the map.

Start the simulated robot

export TURTLEBOT3_MODEL=burger

• This defines which version of the Turtlebot3 will be simulated
• We suggest you add this line to your setup.bash or ~/.bashrc file.
  • Otherwise, you will need export the TURTLEBOT3_MODEL variable for each terminal below.

ros2 launch turtlebot3_gazebo turtlebot3_world.launch.py

• Starts the simulated environment of the ROBOTIS Turtlebot3 world with the simulated Turtlebot3

Start localization

With an unknown map, ROS 2 Cartographer will build a SLAM map of the simulated environment

ros2 launch flex_nav_turtlebot3_demo_bringup cartographer.launch.py use_sim_time:=True

• This is a custom version based on turtlebot3_cartographer
• Starts ROS 2 Cartographer to build a map
• Sets use_sim_time to true instead of the robot running in real time
• Again, be sure TURTLEBOT3_MODEL is set!

or

AMCL can be used to perform localization relative to known map

ros2 launch flex_nav_turtlebot3_demo_bringup amcl.launch.py use_sim_time:=True

or

Fake localization can be used to define localization given ground truth from simulation

ros2 launch flex_nav_turtlebot3_demo_bringup fake.launch.py use_sim_time:=True

Note: Fake localization requires a version of the turtlebot3 model.sdf that includes

    <!-- publish ground truth -->
    <plugin name="turtlebot3_ground_truth" filename="libgazebo_ros_p3d.so">
        <always_on>true</always_on>
        <update_rate>50.0</update_rate>
        <body_name>base_footprint</body_name>
        <gaussian_noise>0.001</gaussian_noise>
        <frame_name>world</frame_name>
        <xyz_offset>0 0 0</xyz_offset>
        <rpy_offset>0 0 0</rpy_offset>
        <ros>
          <!--https://github.com/ros-simulation/gazebo_ros_pkgs/issues/1318-->
          <remapping>odom:=ground_truth</remapping>
        </ros>
    </plugin>

See ROBOTIS-GIT/turtlebot3_simulations#201 for details.

Visualization

Start RViz separately.

For the basic demos, use

ros2 launch flex_nav_turtlebot3_demo_bringup rviz_flex_nav_demo.launch.py use_sim_time:=True

For the pure pursuit demos, use

ros2 launch flex_nav_turtlebot3_demo_bringup rviz_pure_pursuit.launch.py use_sim_time:=True

Displays a standard view of transforms of Turtlebot3, sensor data, with maps, and paths displayed

These custom versions adds the follow robot model, path, and global cost map to the default setup.

• A Path to the RViz display and set the topic to /high_level_planner/plan
• A RobotModel (uses the /robot_description topic)
• A Map showing the topic /global_costmap/costmap
• The 2D Goal Pose publishes to the topic /flex_nav_global/goal

Startup of Flexible Navigation

Flexible Navigation requires startup of planning and control nodes, as well as the FlexBE behavior engine and UI.

Note: After a clean build, be sure that nwjs is installed by using ros2 run flexbe_app nwjs_install

Three options:

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To launch all of Flexbe -- Onboard Behavior Executive and Operator Control Station -- in one terminal use

ros2 launch flexbe_app flexbe_full.launch.py use_sim_time:=True

or

to launch onboard and OCS in two separate terminals use:

ros2 launch flexbe_onboard behavior_onboard.launch.py use_sim_time:=True

ros2 launch flexbe_app flexbe_ocs.launch.py use_sim_time:=True

or

to launch each component separately in their own terminal, use

ros2 launch flexbe_onboard behavior_onboard.launch.py use_sim_time:=True

ros2 run flexbe_mirror behavior_mirror_sm --ros-args --remap __node:="behavior_mirror" -p use_sim_time:=True

ros2 run flexbe_widget be_launcher --ros-args --remap name:="behavior_launcher" -p use_sim_time:=True

ros2 run flexbe_app run_app --ros-args --remap name:="flexbe_app" -p use_sim_time:=True

These commands start the onboard FlexBE behavior engine and FlexBE App UI and other components

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Then start one (and only one) of the following launches that starts the planning and control nodes:

ros2 launch flex_nav_turtlebot3_demo_bringup flex.launch.py

• This version uses a 2-level planner as a demonstration.
  • The global planner plans over the full map, with sensor data
  • The local planner plans over smaller window trying to follow the global path

or

ros2 launch flex_nav_turtlebot3_demo_bringup flex_multi_level.launch.py

• This version uses a 3-level planner as a demonstration.

  • The high-level planner is based only on the static map
  • The mid-level planner using only local obstacle sensing
  • The low-level planner using the ROS 2 Navigation2 DWBLocalPlanner

• The mid- and low-level planners run concurrently as they try to follow the global path defined by the high-level planner.

or

ros2 launch flex_nav_turtlebot3_demo_bringup flex_four_level.launch.py

• This version uses a 4-level planner as a demonstration.

  • The high-level planner is based only on the static map
  • The mid-level planner using only local obstacle sensing
  • The low-mid-level planner using only local obstacle sensing
  • The low-level planner using the ROS 2 Navigation2 DWBLocalPlanner

• The mid- and low-level planners run concurrently as they try to follow the global path defined by the high-level planner.

or

ros2 launch flex_nav_turtlebot3_demo_bringup pure_pursuit.launch.py

• This version loads a defined patrol path based on static map
  • Be sure to use either fake or amcl for localization relative to known map locations for this demo
  • The system uses basic pure pursuit path following node.
  • This demo does NOT have local obstacle avoidance, and is mainly to demonstrate GetPathByName and PurePursuit nodes.

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FlexBE Operation

After startup, all control is through the FlexBE App operator interface and RViz.

• First load the desired behavior through the FlexBE Behavior Dashboard tab.

  • The behavior should match the flex launch started above.
    • 'flex.launch' --> Turtlebot3 Flex Planner
    • 'flex_multi_level.launch' --> Turtlebot3 Multi Level Flex Planner
    • 'flex_four_level.launch' --> Turtlebot3 Four-Level Flex Planner
    • 'pure_pursuit.launch' --> Turtlebot3 Pure Pursuit Patrol

• Examine (but don't modify yet!) the behavior using the Statemachine Editor button on FlexBE app

  • Click on a state to see the configurable parameters

• Execute the behavior via the FlexBE Runtime Control tab.

  • Then Start Execution

• The system requires the operator to input a 2D Nav Goal via the RViz screen

  • If the system is in low autonomy or higher, the system will request a global plan as soon as the goal is received
  • If the autonomy level is off (default), then the operator will need to confirm receipt of the goal by clicking the done transition.

• After requesting a path to the goal, the resulting plan will be visualized in the RViz window.

  • If the system is not in full autonomy mode, the operator must confirm that the system should execute the plan via the FlexBE UI
  • If the operator sets the Runtime Executive to full autonomy, the plan will automatically be executed.
  • In less than full autonomy, the operator can request a recovery behavior at this point.

  

• Once execution of this plan is complete, FlexBE will seek permission to continue planning

  • In full autonomy, the system will automatically transition to requesting a new goal
  • In any autonomy level less than full, the system will require an operator decision to continue

Whenever a plan is being executed, the FlexBE state machine transitions to a concurrent node that uses on-line planners to refine the plans as the robot moves, and also monitors the Turtlebot bumper status for collision.
The operator can terminate the execution early by selecting the appropriate transition in the FlexBE UI.
If this low level plan fails, the robot will request permission to initiate a recovery behavior; in full autonomy the system automatically initiates the recovery.

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Publications

Please use the following publications for reference when using Flexible Navigation:

• David C. Conner and Justin Willis, "Flexible Navigation: Finite state machine-based integrated navigation and control for ROS enabled robots," IEEE SoutheastCon 2017.

• Joshua Zutell, David C. Conner and Philipp Schillinger, "ROS 2-Based Flexible Behavior Engine for Flexible Navigation ,", IEEE SouthEastCon 2022.

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