robotball

Packages for spherical robots developed by LARICS and TU Delft.

This repository currently consists of following packages:

• robotball_arduino: Arduino files required for driving the robot.
• robotball_control: Automatic control of robots (PID controllers, velocity trackers, ...)
• robotball_driver: Driver acting as a basic interface between Arduino and ROS, including joystick control.
• robotball_localization: External localization and state estimation (Kalman filter, Pozyx positioning, ...)
• robotball_msgs: Custom ROS messages.
• robotball_simulation: Simple simulator for testing.

For detailed information about each package, please look at their respective READMEs.

Before you start

Requirements

• Ubuntu 18.04 or Ubuntu 20.04
• ROS Melodic or ROS Noetic
• ROS packages, can be installed with sudo apt install ros-noetic-<package>.
  • joy
  • rosserial
  • teleop-twist-joy
  • teleop-twist-keyboard
  • tf-conversions
  • twist-mux
• Python 3.x
• Python libraries, can be installed with python3 -m pip install <library>.
  • numpy
  • pypozyx
  • pyserial
  • scipy

Installation

1. Install all the requirements.
2. Create a new catkin workspace or use an existing one. Most commonly this is ~/catkin_ws/
3. Clone the repository in the src folder of your workspace.

   $ cd <path_to_your_ws>/src/
   $ git clone git@github.com:larics/robotball.git

4. Build everything using catkin_tools (recommended):

   $ catkin build

   or catkin_make (not recommended):

   $ cd <path_to_your_ws>
   $ catkin_make

5. Set up .bashrc on your robot:

   # ROS WORKSPACES -> Standard ROS stuff.
   source /opt/ros/noetic/setup.bash
   source /home/raspi/catkin_ws/devel/setup.bash
   
   # Set up ROS for remote master. 
   # Robot's IP is automatically determined.
   # Master's IP needs to be set manually.
   export ROS_IP=$(ip -o route get to 8.8.8.8 | sed -n 's/.*src \([0-9.]\+\).*/\1/p')
   export ROS_MASTER_URI=http://192.168.140.154:11311
   export NAMESPACE="robot_$(echo $HOSTNAME | sed 's/[^0-9]*//g')"
   
   # Useful aliases and custom functions.
   source /home/raspi/catkin_ws/src/robotball/shell_additions/aliases.sh
   source /home/raspi/catkin_ws/src/robotball/shell_additions/git_scripts.sh
   source /home/raspi/catkin_ws/src/robotball/shell_additions/usb_setup.sh

   Don't forget to re-source .bashrc to apply changes.
6. Set up symlinks for Arduino and Pozyx.
   1. Connect only the Arduino and run usb_setup_arduino.
   2. Disconnect Arduino and connect Pozyx. Then run usb_setup_pozyx.
   3. Reconnect Pozyx and reboot.
7. Check individual sub-packages for additional instructions.

Usage

In general:

1. If needed, make changes in Arduino sketch.
2. Compile and upload. (See Arduino README)
3. Start essential things on the central computer
   1. roscore
   2. rosrun joy joy_node
   3. rosrun rqt_reconfigure rqt_reconfigure
   4. rviz
4. Start the driver on the robot: roslaunch robotball_driver driver.launch
5. Start the Pozyx scheduler on the central computer: roslaunch robotball_localization remote_scheduler.launch
6. Start Pozyx localization on the robot: roslaunch robotball_localization localize.launch
7. Start one of the controllers, e.g. roslaunch robotball_control billiard.launch

Future work

###TODO

• Analyze and fix issues with BNO-055 IMU. Sometimes it freezes and stops sending new data. The best guees at the moment is that it happens when the compass is close to a large metal or magnet because at the same time calibration status on all registers goes to zero.
• Calibrate the odometry. It didn't make sense to deal with calibration because of the frequent and large wheel slips. Once the inner structure is redesigned, it should be easier.
• Fuse odometry data, IMU, and Pozyx for more reliable localization.
• Prepare a launch procedure for everything that needs to run on the central computer. This includes common parameters used on all robots, such as default trajectory parameters.
• Provide an interface for the simulation that will be the same as for the real robots.
• Analyze and fix issues in communication between Raspberry Pi and Arduino. Maybe rosserial isn't the best solution and we could do something custom.
• Proper cascade PID control. Speed controller gives a pitch (acceleration) reference to the pitch controller. It controls the motors to maintain the given pitch.
• Software support for wireless charging. This includes self-orientation system; navigating, entering, and exiting the charger; and charging monitoring.
• Implement a single Dynamic Reconfigure for all robots when using Billiard controller.

Bug tracking and feature requests.

If you discover bugs or missing documentation, have a question or a feature request, or something simply doesn't work, please create a new issue and label it with an appropriate label.