"# Crowd_avoidance-w-ubuntu22-raspi-kobuki"

Welcome to Crowd_avoidance-w-ubuntu22-raspi-kobuki!

By following this tutorial, you will be able to run a basic crowd_avoidance algorithm. This github project was designed for specific hardware but the programs can be adjusted.

System overview

Hardware

Raspberry pi 4 Ydlidar X2L Kobuki base micro sd card

Software

Raspberry pi 4: OS: Ubuntu 22.04 Python version: 3.8.10 Cuda version: 11.5 ROS version: Humble Turtlebot2i:

Setup

The first step is to flash ubuntu 22.04 (64bits) image to your SD Card from Raspberry Pi Imager. (Note: If rapberry py 2,3 and 4 use ubuntu server 64 bits) Once you have flashed the image you finish installing the system.

Step 1: Install Ubuntu 22.04 Server/Desktop Flash Ubuntu 22.04 (64-bit) to your microSD card using Raspberry Pi Imager. Boot up the Raspberry Pi 4.

Step 2: Update System Ensure the system is up to date.

bash Copy code sudo apt update && sudo apt upgrade -y

Step 3: Install ROS2 (Humble) Set up sources and keys:

bash Copy code sudo apt install -y software-properties-common sudo add-apt-repository universe sudo apt update && sudo apt install curl gnupg lsb-release -y

sudo curl -sSL https://raw.githubusercontent.com/ros/rosdistro/master/ros.asc | sudo apt-key add - sudo sh -c 'echo "deb [arch=arm64] http://packages.ros.org/ros2/ubuntu $(lsb_release -cs) main" > /etc/apt/sources.list.d/ros2.list' Install ROS2 Humble Desktop (includes rviz2, tools, etc.): bash Copy code sudo apt update && sudo apt install -y ros-humble-desktop Set up ROS2 Environment: Add the following to your ~/.bashrc file for persistent setup.

bash Copy code echo "source /opt/ros/humble/setup.bash" >> ~/.bashrc source ~/.bashrc

Step 4: Install Build Tools and Colcon Install development tools and colcon for building packages.

bash Copy code sudo apt install -y python3-pip python3-colcon-common-extensions python3-rosdep

Initialize and update rosdep:

bash Copy code sudo rosdep init rosdep update

Step 5: Install Dependencies YDLidar SDK (required for YDLidar ROS2 driver):

bash Copy code cd ~ git clone https://github.com/YDLIDAR/YDLidar-SDK.git cd YDLidar-SDK cmake .. make -j$(nproc) sudo make install

Problem encountered, can't locate ydlidar_config.h when make. SOLUTION

1. Clean Build Directory The build directory might have stale files or incorrect configurations. Start fresh.

bash Copy code cd ~/YDLidar-SDK rm -rf build mkdir build cd build 2. Configure and Generate CMake Files Re-run CMake with proper options:

bash Copy code cmake .. If the ydlidar_config.h is still not generated, check the output of the CMake command. Look for any warnings or missing dependencies.

3. Locate the Missing ydlidar_config.h The ydlidar_config.h file is typically generated during the cmake step or located in a specific directory.

Check if the file is missing from build: bash Copy code find ~/YDLidar-SDK -name ydlidar_config.h If it doesn’t exist, that confirms a configuration issue during CMake.

4. Manually Generate or Copy the File If the file is not generated, some versions of YDLidar-SDK might require you to manually include it:

Locate a sample ydlidar_config.h template. It may exist under src or core directories. bash Copy code cd ~/YDLidar-SDK cp ./src/ydlidar_config.h.in ./core/common/ydlidar_config.h Or generate the file from the .in template if available.

5. Retry Building the SDK Run the build process again:

bash Copy code cd ~/YDLidar-SDK/build cmake .. make -j$(nproc)

YDLidar ROS2 Driver:

bash Copy code cd ~ mkdir -p ros2_ws/src cd ydlidar_ws/src git clone https://github.com/YDLIDAR/ydlidar_ros2_driver.git branch -humble

Build the Workspace:

bash Copy code cd ~/ colcon build --symlink-install source install/setup.bash echo "source ~/ydlidar_ws/install/setup.bash" >> ~/.bashrc source ~/.bashrc

Step 6: Install Required Tools SLAM and Navigation2: Install Navigation2 stack and SLAM tool:

bash Copy code sudo apt install -y ros-humble-navigation2 ros-humble-nav2-bringup ros-humble-slam-toolbox

People Detection Tools (optional packages for visualization):

bash Copy code sudo apt install -y ros-humble-openvino-node ros-humble-rviz2

Step 7: Setup Serial Port for YDLidar Grant permissions for the Lidar’s serial port (assumes /dev/ttyUSB0):

bash Copy code sudo chmod 666 /dev/ttyUSB0

Step 8: Install Kobuki ROS2 Packages Install kobuki_ros2 (or its forked driver for ROS2 Humble):

bash Copy code sudo apt update sudo mkdir kobuki_ws sudo mkdir kobuki_ws/src cd ~/kobuki_ws/src git clone https://github.com/kobuki-base/kobuki_ros.git

Step 9: Verify Kobuki Base Connection Plug in the Kobuki base via USB and find the serial port:

bash Copy code ls /dev/ttyUSB*

Grant access to the port (assume it's /dev/ttyUSB1):

bash Copy code sudo chmod 666 /dev/ttyUSB1

Launch the Kobuki base driver node to check connectivity:

bash Copy code ros2 launch kobuki_node kobuki_node.launch.py device:=/dev/ttyUSB1

Check if topics like /odom (odometry) and /cmd_vel (velocity commands) are published:

bash Copy code ros2 topic list

Options to Resolve cmd_vel_mux Issue

1. Check If cmd_vel_mux Is Truly Required The kobuki_keyop package might reference cmd_vel_mux, but it might not be essential for your current use case. If kobuki_keyop is optional for your project, you can continue without it. Skip to Step 3 if this is the case.
2. Use an Alternative (e.g., twist_mux) In ROS 2, the cmd_vel_mux functionality is often replaced by twist_mux.

Install twist_mux:

bash Copy code sudo apt install ros-humble-twist-mux Modify the kobuki_keyop package to use twist_mux:

Edit the package.xml file: xml Copy code twist_mux Update any launch files or configuration files to reference twist_mux. Rebuild the workspace:

bash Copy code colcon build --symlink-install

Step 10: Launch YDLidar Driver Run the YDLidar ROS2 Driver:

bash Copy code ros2 launch ydlidar_ros2_driver ydlidar_launch.py Verify Scan Topic: Check the /scan topic:

bash Copy code ros2 topic echo /scan

Step 11: Run SLAM for Mapping Launch the SLAM Toolbox for real-time mapping:

bash Copy code ros2 launch slam_toolbox online_async_launch.py

Visualize the map in RViz:

bash Copy code rviz2

Add: LaserScan topic: /scan Map topic: /map

Step 12: Run Navigation2 Launch the Navigation2 stack with your map and setup:

bash Copy code ros2 launch nav2_bringup bringup_launch.py use_sim_time:=False map:=/path/to/map.yaml

Step 13: Run People Detection Node Assuming you are using a node that publishes people positions to /people_positions:

bash Copy code ros2 run people_detection_pkg people_detection_node

Step 14: Build and Run Add the node to your workspace: Create a ROS2 package if you don’t have one:

bash Copy code cd ~/ydlidar_ws/src ros2 pkg create kobuki_avoidance --build-type ament_python --dependencies rclpy sensor_msgs geometry_msgs std_msgs

Place kobuki_mover.py in the kobuki_avoidance package’s scripts folder.

Make the script executable:

bash Copy code chmod +x ~/ydlidar_ws/src/kobuki_avoidance/scripts/kobuki_mover.py

Build the workspace:

bash Copy code cd ~/ydlidar_ws colcon build source install/setup.bash

Run the Kobuki Movement Node:

bash Copy code ros2 run kobuki_avoidance kobuki_mover.py

Step 15: Full Launch Workflow Terminal 1: Start Kobuki Driver:

bash Copy code ros2 launch kobuki_node kobuki_node.launch.py device:=/dev/ttyUSB1

Terminal 2: Launch LiDAR driver:

bash Copy code ros2 launch ydlidar_ros2_driver ydlidar_launch.py

Terminal 3: Start SLAM Toolbox:

bash Copy code ros2 launch slam_toolbox online_async_launch.py Terminal 4: Start People Detection Node:

bash Copy code ros2 run people_detection_pkg people_detection_node Terminal 5: Run the Kobuki Movement Logic:

bash Copy code ros2 run kobuki_avoidance kobuki_mover.py Testing and Debugging

RViz2 Visualization:

View /scan topic for LiDAR data. View /cmd_vel commands.

bash Copy code rviz2

Check Kobuki Motion: Monitor the Kobuki’s movement using:

bash Copy code ros2 topic echo /cmd_vel