Workshop

  • A small overview of the Bavarian-Hungarian Self-driving vehicles workshop.
  • Date: 2023.11.03.
  • Place: Győr, Hungary.

megoldas_zala23 ROS 1 package

🤖 In the following a very simple wall/gap following approach will be presented and described. The origin of he code is based on the work of Suresh Babu (University of Virginia, license). Link to the original code: github.com/linklab-uva/f1tenth_gtc_tutorial.

The name of the package is a comes from a hungarian expression (megoldas: solution / Lösung).

The robot used in the competition

Wheeltec / Roboworks Rosbot mini Ackermann robot main

On-board computer

  • Nvidia Jetson Nano

Sensors

  • Orbbec Depth Camera
  • LSN10 LIDAR

Video

Usage

Prerequisites:

  • WiFi-enabled computer with Ubuntu 18.04 / 20.04 operating system and ROS Melodic / Noetic installation
  • Internet access (Ethernet cable or WiFi)
  1. Turn on the robot platform.
  2. Use the computer to connect to the WiFi network created by the robot. The name of the WiFi network is unique for each robot platform, the # at the end of the SSID changes according to the number of the robot platform: 
    SSID: WHEELTEC_CAR_5.5_#
Password: dongguan
  3. Use SSH to connect to the on-board computer of the robot platform with the following terminal command: 
    ssh wheeltec@192.168.0.100

    A password will be required, the default password is dongguan

Internet access on the robot platform

Software packages can be downloaded to the on-board computer of the robot platform, which requires internet access.

  • Ethernet: connect the Ethernet cable to the Ethernet port of the on-board computer of the robot platform.
  • WiFi: after issuing the nmtui terminal command, connect to the available WiFi network. 
    nmtui

Install the ROS 1 package

After installation, the functions of the robot platform can be accessed using ROS. The sample solution of the competition can also be deployed by ROS.

Create a workspace and install the sample solution on the robot:

mkdir -p ~/workshop_ws/src

cd ~/workshop_ws/

catkin init

cd ~/workshop_ws/src/

git clone https://github.com/robotverseny/megoldas_zala23

cd ~/workshop_ws/

catkin build megoldas_zala23

echo "source /home/wheeltec/workshop_ws/devel/setup.bash" >> ~/.bashrc

source ~/.bashrc

Install screen

sudo apt install mc screen

Install jks visualization rviz plugin: depending on ROS 1 version (melodic / noetic):

sudo apt install ros-melodic-jsk-rviz-plugins

sudo apt install ros-noetic-jsk-rviz-plugins

Usage

The script verseny_start.sh sets the required environmental variables, starts the ROS nodes and finally after 2 minutes stops everything. Have a look at the code: verseny_start.sh

rosrun megoldas_zala23 verseny_start.sh

The verseny_start.sh shell script usually launches several virtual terminals, such as: roscore, turn_on_wheeltec_robot, lsn10_lidar, megoldas1.launch. All components of the solution can be stopped with the following command:

rosrun megoldas_zala23 stop_all.sh

Further commands:

  • list screen: screen -ls
  • restore screen: screen -r roscore / screen -r turn_on_wheeltec_robot / screen -r megoldas1
  • detach: Ctrl-a + Ctrl-d

ROS connection

The ROS topics advertised by the robot platform are also available on the computer connected to the platform, with the appropriate setting of the ROS_MASTER_URI variable:

export ROS_MASTER_URI=http://192.168.0.100:11311

After the appropriate setting of the variable, the topics can be listed and visualized using Rviz:

rostopic list

rosrun rviz rviz

Some explanatory animations 

roslaunch megoldas_zala23 rviz1.launch

Start solution per component

The solution can also be started per component, not just as a single shell script. This requires four terminal windows on the on-board computer of the robot platform and issuing the following commands per terminal:

roscore

roslaunch turn_on_wheeltec_robot turn_on_wheeltec_robot.launch

roslaunch lsn10 lsn10.launch

roslaunch megoldas_zala23 megoldas1.launch

Additional information

Workspaces 

~/wheeltec_robot/src
~/catkin_workspace/src
~/workshop_ws/src/

Topic management 

rostopic hz /scan
rostopic echo /scan -n1
rostopic type /scan

sensor_msgs/LaserScan

Robot platform language settings 

sudo dpkg-reconfigure locales

reboot

Rosbag management 

cd ~/rosbags
rosbag record -a -o test1

rsync -avzh --progress wheeltec@192.168.0.100:/home/wheeltec/rosbags/ /mnt/c/bag/wheeltec/
rosbag info test1_2023-03-30-12-37-22.bag
rosbag play test1_2023-03-30-12-37-22.bag

You can even visualize rosbags in Foxglove studio:

Alt text

Download rosbags