Stembot

An example robot that demonstrates the capabilities of the ROS2 ecosystem.

Package installation Instructions

1. Open a terminal and navigate to a directory of your choice using ls and cd commands.
2. Clone the repository:

   git clone https://github.com/treedel/stembot.git
   cd stembot

3. Build the packages using:

   colcon build

4. Source the setup script before running any package (do this in every new terminal):

   source install/setup.bash

   Make sure you are in the stembot folder before running the command.

Package Instructions

Experiment 1: Robot teleoperation

• Launch the Gazebo simulator:

  ros2 launch stembot_gazebo gazebo.launch.py

  This starts the Gazebo simulator along with supporting nodes to simulate the robot.
• Run the teleop_twist_keyboard node in another terminal to control the robot:

  ros2 run teleop_twist_keyboard teleop_twist_keyboard

  This node publishes velocity commands (cmd_vel) based on keyboard inputs.

Experiment 2: Robot_Localization Based Odometry

• Launch the Gazebo simulator with EKF odometry enabled:

  ros2 launch stembot_gazebo gazebo.launch.py use_ekf_odom:=true

Experiment 3: Robot state manipulation using nodes

There are two approaches for this experiment: using a prebuilt node or creating your own.

Option 1: Using the Prebuilt Node

• Launch the Gazebo simulator:

  ros2 launch stembot_gazebo gazebo.launch.py

• Run the two_point_looper node in another terminal after sourcing:

  ros2 run stembot_state_manipulator two_point_looper

Option 2: Creating Your Own Node

1. Change to the src folder and create an empty ROS2 package:

   ros2 pkg create --build-type ament_python --license Apache-2.0 <package_name>

2. Navigate to the newly created package directory:

   cd src/<package_name>/<package_name>

   Here, you'll find a __init__.py file. Create a new Python script for your node in this folder.
3. Open setup.py (located in src/<package_name>) and add an entry point for the node under console_scripts as '<node_name> = <package_name>.<python_file_name>:main'. It should look similar to this:

   entry_points={
       'console_scripts': [
           'two_point_looper = stembot_state_manipulator.two_point_looper:main'
       ],
   },

4. Build, source, and run the node:

   colcon build
   source install/setup.bash
   ros2 run <package_name> <node_name>

Note: You can find reference code in the code folder or the src package files.

Experiment 4: Obstacle Avoidance using 2D Lidar

• Use the prebuilt obstacle_avoider node:

  ros2 run stembot_obstacle_avoidance obstacle_avoider

• Alternatively, create your own package and implement the obstacle avoidance logic in a custom node.
• Don't forget to launch the simulator before running the node.

Experiment 5: Performing SLAM and Mapping

1. Launch the Gazebo simulator with EKF odometry:

   ros2 launch stembot_gazebo gazebo.launch.py use_ekf_odom:=true world_name:=shapes.sdf

   The world_name is a parameter that accepts demo world names from gazebo (ex: shapes.sdf, empty.sdf, etc)
2. Launch the SLAM nodes for mapping:

   ros2 launch stembot_mapping toolbox_oma.launch.py use_sim_time:=true

   The use_sim_time:=true parameter tells the system to use Gazebo's simulated clock.
3. Manually move the robot to explore the environment:

   ros2 run teleop_twist_keyboard teleop_twist_keyboard