This repo contains ROS2 packages for the Waveshare Alphabot2-Pi mobile robot:
- alphabot2: nodes used to manage Alphabot2 sensors and actuators.
- alphabot2_interfaces: custom interfaces (ROS messages) designed for AlphaBot2.
The current implementation includes nodes to manage the motors, the IR obstacle sensors and the camera. There is also a node for QR-code detection.
Please, see here for the ROS2 nodes topology and TODO.
The code has been originally developed for my final project of the Robotics course, University of Brescia.
-
Robot: Waveshare Alphabot2-Pi mobile robot (see here), equipped with a Raspberry Pi4 (8 GB).
-
OS: Ubuntu Server 20.04 (Focal Fossa) x64.
Install Ubuntu Server 20.04 x64 on the RPi4 (see here).
Connect the RPi4 to WiFi and add auto-connection at boot (see here).
Install ROS2 Foxy Fitzroy Base (reference) and the dependencies:
sudo apt update && sudo apt install curl gnupg2 lsb-release
sudo curl -sSL https://raw.githubusercontent.com/ros/rosdistro/master/ros.key -o /usr/share/keyrings/ros-archive-keyring.gpg
echo "deb [arch=$(dpkg --print-architecture) signed-by=/usr/share/keyrings/ros-archive-keyring.gpg] https://packages.ros.org/ros2/ubuntu $(source /etc/os-release && echo $UBUNTU_CODENAME) main" | sudo tee /etc/apt/sources.list.d/ros2.list > /dev/null
sudo apt update && sudo apt install ros-foxy-ros-base
Install python dependencies:
sudo apt install python3-pip python3-colcon-common-extensions python3-rosdep2
pip3 install RPi.GPIO argcomplete
Initialize rosdep and source the ROS2 core environment:
rosdep update
source /opt/ros/foxy/setup.bash
Fix GPiO permission problem (reference):
sudo apt install rpi.gpio-common
sudo usermod -aG dialout ubuntu
Source the ROS2 core environment (underlay) and the ROS2 local workspaces (overlays) in the file .bashrc
so that
they are automatically sourced in every bash shell:
source /opt/ros/foxy/setup.bash
source /path_to_your_ros_ws/install/local_setup.bash
Plug an additional external network adapter and setup it as a WiFi Access Point to easily SSH into the RPi4. Please follow this guide and also these additional tricks:
- put
optional: true
for wlan0 in 50-cloud-init.yaml to prevent endless booting time. - don't put
After=network-online.target
andWants=network-online.target
sudo systemctl enable dnsmasq
For the Raspberry Camera management we use the ROS2 implementation v4l2_camera (reference).
Install required tools:
sudo apt install v4l-utils
echo bcm2835-v4l2 | sudo tee -a /etc/modules
Add start_x=1
in /boot/config.txt to enable the camera module.
Clone the camera node and dependencies needed to compress images into the src
folder of your ros workspace:
git clone -b foxy https://gitlab.com/boldhearts/ros2_v4l2_camera.git
cd ros2_v4l2_camera ; git checkout 269573bd ; cd ..
git clone -b ros2 https://github.com/ros-perception/vision_opencv.git
cd vision_opencv ; git checkout 9ea89084 ; cd ..
git clone -b ros2 https://github.com/ros-perception/image_common.git
cd image_common ; git checkout 9729de81 ; cd ..
git clone -b ros2 https://github.com/ros-perception/image_transport_plugins.git
cd image_transport_plugins ; git checkout 7ca90727 ; cd ..
To fix building errors, modify camera_info_manager.cpp:46
(in image_common/camera_info_manager/
) to:
#include "rcpputils/get_env.hpp"
Source build:
cd your_ros_ws
rosdep install --from-paths src -r -y
colcon build
If you get a build error like this:
Imported target "Boost::python" includes non-existent path
"/include"
in its INTERFACE_INCLUDE_DIRECTORIES.
The Boost library may be installed in /usr/include and not in /include. You can fix the problem creating a symlink:
sudo ln -s /usr/include /include
If /usr/include is not your case, you should figure out where the Boost library is placed and create a symlink accordingly.
After you have all the requirements satisfied, clone this repo in your_ros_ws/src
and build it:
git clone https://github.com/Mik3Rizzo/alphabot2-ros2
cd your_ros_ws
colcon build
I recommend to run all the nodes at once using the launch file:
ros2 launch alphabot2 alphabot2_launch.py
To move the robot, publish a Twist
ROS2 message on the alphabot2/cmd_vel
topic. For example:
ros2 topic pub --rate 1 alphabot2/cmd_vel geometry_msgs/msg/Twist "{linear: {x: 1.0, y: 0.0, z: 0.0}, angular: {x: 0.0, y: 0.0, z: 5.0}}"
This command publishes every second a linear velocity of 1 m/s
and an angular rate of 5 rad/s
.
Please note that the maximum theoretical linear velocity is
1.65 m/s
while the angular rate is38.8 rad/s
. These quantities are estimated with the robot suspended from the floor and supplied with two Sony US14500VR Li-ion 3.7V batteries at full charge. In these conditions the maximum wheel RPM is 750.
Michele Rizzo, Master's Degree Computer Engineering student at University of Brescia.
- Mail: [email protected].
- Github: Mik3Rizzo
Please, feel free to contact me for informations or problems.