Raspberry Pi Camera

The diffbot robot uses the UbiquityRobotics/raspicam_node to interface the Raspberry Pi Camera v2.

Ubuntu 20.04 only

raspicam_node uses the Raspberry Pi's legacy camera interface (MMAL), which works on the robot's Ubuntu 20.04. Current systems use libcamera instead: Raspberry Pi OS since Bullseye, and Bookworm no longer has the legacy interface. A driver for current systems, for DiffBot and Remo, is planned in diffbot#111.

RPi Camera v2.

Setup

Currently there exists no binary of the raspicam_node for ROS noetic (only for kinetic there is the ros-kinetic-raspicam-node). To work with the raspicam_node for ROS Noetic, you have to build it from source with steps outlined in the build instructions of the readme. For completeness, these steps are listed here:

First go to your catkin_ws cd ~/catkin_ws/src and download the source for this node by running

git clone https://github.com/UbiquityRobotics/raspicam_node.git

rosdep doesn't know two of its dependencies: the Raspberry Pi's camera libraries libraspberrypi0 and libraspberrypi-dev. Ubuntu 20.04 for the Raspberry Pi has them as packages (in focal-updates, universe). The rosdep rules for them that Ubiquity Robotics published (UbiquityRobotics/rosdep, raspberry-pi.yaml) are no longer online, so add the rules as a local file, and tell rosdep where it is. The first command removes the entry for the old rules that earlier versions of this page added, if it's there: with it, rosdep update fails.

sudo rm -f /etc/ros/rosdep/sources.list.d/30-ubiquity.list
sudo tee /etc/ros/rosdep/raspberry-pi.yaml > /dev/null << 'EOF'
libraspberrypi0:
  ubuntu:
    apt:
      packages: [libraspberrypi0]
libraspberrypi-dev:
  ubuntu:
    apt:
      packages: [libraspberrypi-dev]
EOF
echo "yaml file:///etc/ros/rosdep/raspberry-pi.yaml" | sudo tee /etc/ros/rosdep/sources.list.d/30-raspberry-pi.list

Then update rosdep's index:

rosdep update --rosdistro noetic

Next, we parse the package.xml file for required dependencies and also install them with the rosdep command:

cd ~/catkin_ws
rosdep install --from-paths src --ignore-src --rosdistro=noetic -y

Finally, you can compile the code with the catkin build command from catkin-tools or use the legacy catkin_make command.

Running the node

To publish the camera image on the /raw/image/compressed topic run the following on the SBC of the robot:

roslaunch raspicam_node camerav2_410x308_30fps.launch

Running rostopic list should show the topics of raspicam node:

/raspicam_node/camera_info
/raspicam_node/image/compressed
/raspicam_node/parameter_descriptions
/raspicam_node/parameter_updates

To view the compressed image run the following command on your development PC:

rosrun image_view image_view image:=/raspicam_node/image _image_transport:=compressed

This will open up a window where you can see the camera image. If it is dark, check if you removed the lense protection ;-)

Note

There is also a rpicamera.launch in the diffbot_bringup package which you can make use of:

roslaunch diffbot_bringup rpicamera.launch

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