Repository for the ATOM differential mobile platform running on a Raspberry Pi and its simulation stack in V-REP, based on ROS framework.

Keywords: raspberry pi, robot, hardware, simulation, mobile platform, v-rep

The source code is released under MIT license.

Author(s): Karl Kangur
Maintainer: Karl Kangur, [email protected]
Affiliation: Personal

The atom package has been tested under ROS Kinetic and Ubuntu Mate 16.04 on a Raspberry Pi and Ubuntu 16.04 with V-REP 3.5.0 (rev. 6) for simulation.

sudo apt install -y ros-kinetic-robot-state-publisher
sudo apt install -y ros-kinetic-ros-control
sudo apt install -y ros-kinetic-ros-controllers
sudo apt install -y ros-kinetic-diff-drive-controller
sudo apt install -y ros-kinetic-cv-camera
sudo apt install -y ros-kinetic-joy
sudo apt install -y ros-kinetic-teleop-twist-joy
sudo apt install -y ros-kinetic-map-server
sudo apt install -y ros-kinetic-move-base

To build from source, clone the latest version from this repository into your catkin workspace and compile the package using

mkdir -p ~/catkin_ws/src
cd ~/catkin_ws/src
git clone https://github.com/Nurgak/atom.git
catkin build

For the ROS/V-REP interface to work the VREP_ROOT global variable must be defined, it must point to the V-REP folder, one can add export VREP_ROOT="/home/.../V-REP_..." to ~/.bashrc

No unit tests so far.

Run the main node on the Raspberry Pi with

roslaunch atom_interface_hardware atom_interface_hardware.launch

Run the V-REP simulation with

roslaunch atom_interface_vrep atom_interface_vrep.launch map:=maze
roslaunch atom_interface_vrep atom_interface_vrep.launch map:=duckietown

This will start the simulation interface as well as move_base and R-VIZ visualization. The map argument loads the relevant costmap .yaml file from the map folder.

Note that roscore must be launched first, then V-REP started, the scene loaded and the simulation running. The V-REP scenes are located in atom_interface_vrep/scene.

The maze scene is meant to showcase the move_base node usage to find a traversable path and then navigate it accurately. The goal position is set in R-VIZ.

The duckietown scene places ATOM in a duckietown environment with roads. This is a work in progress where ATOM will eventually be able to navigate roads. Currently it can be used similarly to the maze scene where it navigates only on accessible areas. The map is generated with a custom script under atom_interface_vrep/map/duckietown_map_generator.

• atom_controllers.yaml The joint state controller and the differential drive controller parameters for the ATOM platform.
• base_local_planner_params.yaml Parameters for the local planner, used with move_base package.
• costmap_common_params.yaml Common parameters for the local and global planners, used with move_base package.
• global_costmap_params.yaml Parameters specific for the global planner, used with move_base package.
• local_costmap_params.yaml Parameters specific for the local planner, used with move_base package.

• atom_interface_hardware.launch: launch the hardware interface, sends PWM signals to the H-brige connected to the Raspberry Pi to se wheel speeds.
• atom_interface_vrep.launch: launch the simulation interface with R-VIZ visualization and move_base node.
• atom_ground_control.launch: launch the R-VIZ visualization with joystick interface, meant to be used on remote computer with the physical platform being the master.

Hardware interface between the Raspberry Pi and the mobile platform. It creates the controller manager and exposes the velocity joint interfaces for the left and right drive motors. The joint definitions are taken from the diff_drive_controller, so they only need be defined once in the controller configuration file.

This node sets the PWM signals of the GPIO to set the motor speeds through the L298 dual h-bridge module, according to the joint velocity commands received by diff_drive_controller.

The pins of the L298 are to be connected the following way:

• diff_drive_controller/left_wheel (array, default: [])

  Left wheel names.

• diff_drive_controller/right_wheel (array, default: [])

  Right wheel names.

• diff_drive_controller/publish_rate (float, default: 10)

  Control loop rate.

Node to interface with the V-REP simulation. The names of the joints in the V-REP simulation must agree with the joint names defined in the diff_drive_controller configuration.

• diff_drive_controller/left_wheel (array, default: [])

  Left wheel names.

• diff_drive_controller/right_wheel (array, default: [])

  Right wheel names.

• diff_drive_controller/publish_rate (float, default: 10)

  Control loop rate.