Volksbot ROS2

This project is an adaptation of the original code to the modern ROS2 alternative for the Volksbot rovers (the original ROS version can be found under the branch ROS).

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Prerequisits

• Ubuntu 22.04 or Ubuntu 24.04
• GCC 11.0 or greater
• ROS2 humble

Warning

Other Linux distributions may or may not work correctly. Therefore, it is recommented to use one of the distributions mentioned above. Please let us know your experience and success with other systems.

Important

If you use Ubuntu 24.04, you will probably encounter a Permission Denied error when trying to run the volksbot node. To fix this error regard the section Trouble Shooting - Permission Denied.

Quickstart

Note

For advanced build options regard the section How To Build - Advanced.

How To Build

1. clone the repository locally

   git clone git@github.com:JMUWRobotics/volksbot.git

2. change to the ros2_ws directory

   cd volksbot/ros2_ws

3. set the udev rules (once) so that the motor controllers are recognized by the code. Copy the 42-usb-serial-volksbot.rules from the motor_controller package into your udev rules:

   sudo cp src/motor_controller/42-usb-serial-volksbot.rules /etc/udev/rules.d/

   Afterwards, either restart or reset the udev server to load the new rules:

   udevadm control --reload-rules && udevadm trigger

4. a) on your initial build: source the global ros2 environment:

   source ${ros2_distro}

   b) else source the ROS2 workspace:

   source ./install/setup.bash

5. build the project with the build script volksbuild.sh:

   ./volksbuild.sh

Tip

You can run the build with a set number of concurrent worker threads by supplying an argument to the build script. This is usefull when your system is limited in RAM or your OS freezes while building. (building with 2-4 threads should work on any system):

./volksbuild.sh n

How to Run

The volksbot node from the volksbot package must always be started as this node determines the connected rover and comunicates the configureation over the rover topic to all other nodes:

ros2 run volksbot volksbot

Tip

If you want to select a specific rover supply the name of the rover as an argument:

ros2 run volksbot volksbot [RoverName]

In an other terminal you can run any node or the default launch script praktikum_launch.py of the package volkslaunch, which launches the remaining (not your customs) nodes.

ros2 launch volkslaunch praktikum_launch.py

Caution

When playing back rosbags while connected to the rover you may want to comment out the gamepad_driver node from the launch script to avoid unwanted velocity commands to the motors with the recorded data.

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Documentation & more Information

Regard the following documentation markdowns for further information on usage and configuration of the project:

• Gamepad Driver: Information on how to use the gamepad and the different drive modes.
• Logging: Information on how to set up logging for the packages and how to use the logging macros for debugging and development and console prints.

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Trouble Shooting

Permission Denied

If you are running the volksbot node on Ubuntu 24, you might encounter a Permission Denied error during the selection process. This happens because the program attempts to use ICMP sockets for pinging, which requires specific kernel permissions. By default, some Ubuntu configurations set the allowed group range to 1 0, meaning only the root user is permitted to open these sockets.

To allow all users to use ICMP sockets, you have to type in the command:

sudo sysctl -w net.ipv4.ping_group_range="0 2147483647"

To make this setting permanent, you have to edit your /etc/sysctl.conf and add the line net.ipv4.ping_group_range=0 2147483647.

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Bugs or Issues?

Any Bugs or Issues, please open an issue on this repository or conntact us directly.

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How To Build - Advanced

Tip

When your OS freezes on building consider using less parallel workers by adding --parallel-workers n to the colcon build command (2-4 should usually work for everyone).

When building for the first time:

1. source global ros2 environment

   source ${ros2_distro}

2. only build the SICK LMS package

   colcon build --packages-select sick_scan_xd --cmake-args " -DROS_VERSION=2" " -DLDMRS=0" " -DSCANSEGMENT_XD=0" --event-handlers console_direct+

3. source the ros2 workspace

   source ./install/setup.bash

4. build the remaining packages

   colcon build --packages-ignore sick_scan_xd

Regular building:

Caution

Make sure you are sourced into the workspace with

source ./install/setup.bash

colcon build --packages-ignore sick_scan_xd

or just a subset of the packages:

colcon build --packages-select [package1] [package2] [package3] [...]