This ROS package contains the navigation stack for a custom 4-wheel skid-steer drive robot in Gazebo. The robot is equipped with a 2D-Laser Scanner, a RGBD Camera and an IMU. The purpose of this package is to learn and explore ROS Navigation Stack. The URDF for the robot has a utilitarian design and does not include any mesh files for complex view or geometry. Any one interested with improving the visual aesthetics or geometrical complexity, feel free to do so by modifying the base URDF files.
This project was tested on Ubuntu 20.04 LTS with ROS Noetic. Check the ROS official documentation for the Installation ROS Installation.
- gmapping:
sudo apt install ros-noetic-gmapping - ros_control:
sudo apt install ros-noetic-ros-control ros-noetic-ros-controllers - navigation:
sudo apt install ros-noetic-navigation - robot_localization:
sudo apt install ros-noetic-robot-localization - catkin_tools:
sudo apt install python3-catkin-tools
Follow the steps below to install the package. It has been assumed that the ROS workspace folder name is catkin_ws and is present inside the home folder (~/).
cd ~/catkin_ws/src
git clone https://github.com/prabinrath/armbot_nav.git
catkin build armbot_nav
source ~/catkin_ws/devel/setup.bash
Step 1
roslaunch armbot_nav armbot_gazebo.launch
This will launch the Gazebo simulator to instantiate the robot with controllers and sensors. The gazebo skid-steer drive plugin will publish the odometry transform between odom -> base_link frames. The joint_state_publisher along with the robot_state_publisher will update the TF for the whole robot based on the provided URDF file and realtime motion of the robot in the gazebo environment. This command also pops-up a rviz window with global frame set to map. Visualizations on this window will start after the following step.
Step 2
roslaunch armbot_nav armbot_gmapping.launch
This will start the SLAM node using the gmapping package. It will also publish the map transform between map->odom frames. With this the TF tree will be fully connected and the visualization will start on the rviz window.
Step 3
rosrun armbot_nav armbot_nav_teleop.py
This is a terminal node for sending command velocities to the robot. Use the on screen instructions to manually navigate the robot. While navigating through the gazebo environment the map will get updated in realtime which can be visualized in the rviz window. Once mapping is complete use the command rosrun map_server map_saver -f map to save the generated map for later use.
Step 1
roslaunch armbot_nav armbot_gazebo.launch
Spin up Gazebo and RViz.
Step 2
roslaunch armbot_nav armbot_offline_nav.launch
This will start the map_server, amcl and move_base nodes. Map server will publish the offline map and AMCL will adjust the transform between map->odom frames to localize the robot within the map. With this the TF tree will be fully connected and the visualization will start on the rviz window. Move base will initialize the global and local costmaps for navigation.
Step 3
Use the 2D Nav Goal button on RViz to assign a navigation goal to the robot within the map. Now the robot should navigate to the assigned goal and the same will be visualized on both Gazebo and RViz.
The manual driving involved in the map generation process can become cumbersome for large maps. This process can be automated where the robot autonomously explores the unknown spaces in the environment and generates the map. It requires installation of an additional ROS package called rrt_exploration.
Follow the steps below to install the package. It has been assumed that the ROS workspace folder name is catkin_ws and is present inside the home folder (~/).
cd ~/catkin_ws/src
git clone https://github.com/hasauino/rrt_exploration.git
catkin build rrt_exploration
source ~/catkin_ws/devel/setup.bash
Step 1
roslaunch armbot_nav armbot_gazebo.launch
Spin up Gazebo and RViz.
Step 2
roslaunch armbot_nav armbot_online_nav.launch
This will start the gmapping and move_base nodes. Gmapping will publish the transform between map->odom frames. With this the TF tree will be fully connected and the visualization will start on the rviz window. Move base will initialize the global and local costmaps for navigation.
Step 3
roslaunch armbot_nav rrt_explore.launch
This will start the rrt_exploration node. Please follow the tutorial here to start the autonomous exploration. It involves publishing 5 points in a particular sequence to the rrt_exploration node using the Publish Point button on RViz. With a successful initiation the robot should start exploring the environment autonomously and the same will be visualized on both Gazebo and RViz.
