`my_bot` package

Introduction

This is a ROS2 project of a two wheel robot with simulation in Gazebo. The project is build and tested for ROS_DISTRO humble.Can run in foxy after installing right package for foxy.You can verify your ROS_DISTRO and ROS_VERSION with below command (assuming you have sourced proper ROS underlay if You are having Different ROS installion)

printenv | grep -i ROS

Setting up the project with dependency

Open a terminal (should be in the home directory by default)

mkdir dev_ws/src
git clone https://github.com/jubin123/my_bot.git
cd ..
colcon build --symlink-install

Install the required package and dependency.(note: change humble to foxy to run in ROS_DISTRO foxy)

sudo apt install ros-humble-xacro ros-humble-joint-state-publisher-gui

Installing Gazebo

sudo apt install ros-humble-gazebo-ros-pkgs

Installing ros2_control dependency

sudo apt install ros-humble-ros2-control ros-humble-ros2-controllers ros-humble-gazebo-ros2-control

Setting up and adding dependency for rasperypi

Camera used is Pi Camera V2.

In terminal run

sudo apt install libraspberrypi-bin v4l-utils ros-humble-v4l2-camera ros-humble-image-transport-plugins

Also, use the groups command to confirm you are already in the video group (to allow camera access). If not, run sudo usermod -aG video $USER (this requires log out/restart to take effect).

To check if it thinks the camera is connected .run

vcgencmd get_camera

and we should see supported=1 detected=1 in response.

We can run raspistill -k and the camera stream should come up on the screen, then press x and Enter to exit.

Then, we can run:

v4l2-ctl --list-devices

And there should be an entry for mmal service, platform bcm2835-v4l2, device /dev/video0. That tells us that the V4L2 subsystem can see the camera.

Running simulation and controling the mobile robot

To start the simulation in gazebo world.In terminal go to ~/dev_ws and run below command

source install/setup.bash
ros2 launch my_bot launch_sim.launch.py world:=./src/my_bot/worlds/obstacles.world

If you also want to see visulation in rviz2.In new terminal go to ~/dev_ws and run below command

rviz2 -d src/my_bot/config/drive_bot_lidar_camera.rviz

To Test the control the robot with keyboard.

ros2 run teleop_twist_keyboard teleop_twist_keyboard --ros-args -r /cmd_vel:=/diff_cont/cmd_vel_unstamped

Additional infomation :

Decompressing and republishing image data

Installing plugins image_transport

sudo apt install ros-humble-image-transport-plugins

Installing plugins rqt-image-view for viewing compressed image.

sudo apt install ros-humble-rqt-image-view

To run rqt-image-view for viewing compressed image.

ros2 run rqt_image_view rqt_image_view

To list all the image_transport avliable currently

ros2 run image_transport list_transports

How to create a compressed_image or uncompressed_image and topics (creating a image transport):

Then, to republish a topic we need to specify the type of the input, then the type of the output. We also need to remap some topics, which are in the format {in/out}/{type} (with no type for uncompressed/raw). For example, to remap from a compressed input topic to a raw output topic we use:

ros2 run image_transport republish compressed raw --ros-args -r in/compressed:=/camera/image_raw/compressed -r out:=/camera/my_uncompressed_image

Note, with image_transport, raw means "uncompressed" and has nothing to do with the "raw" in image_raw.

How to add `depth_camera` support : (Is not be used in current projects,might be intrigated in future)

To see add depth camera . In robot.urdf.xacro ,comment <xacro:include filename="camera.xacro" /> and uncomment <xacro:include filename="depth_camera.xacro" /> shown below as requirement.