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We have designed a ROS-based architecture for controlling and managing a rover. The system is distributed between a base station (computer) and the rover itself (Raspberry Pi), with additional components on an Arduino Mega.

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System Architecture Diagram

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System Components

Base Station

  • Hardware: Computer
  • Main Node: benrover_communication/communication_node

Rover

  • Hardware: Raspberry Pi
  • Main Nodes:
    • benrover_navigation/navigation_node
    • benrover_sensors/sensor_node
    • benrover_actuators/actuator_node
    • benrover_energy_management/energy_management_node
    • benrover_interface/interface_node

Motor Control

  • Hardware: Arduino Mega

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Node Descriptions

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benrover_communication/communication_node

  • Role: Manages Wi-Fi communication between the rover and base station, and handles joystick control.
  • Published Topics:
    • /rover_status: Sends rover status information to the base station.
    • /control_command: Sends joystick movement commands to the navigation node.
  • Subscribed Topics:
    • /joy: Receives joystick data (position, buttons).
  • Communication:
    • Wi-Fi: Communicates with the navigation node on the Raspberry Pi.
    • TCP/IP: Used for communication with the navigation node.

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benrover_navigation/navigation_node

  • Role: Manages real-time rover safety using LIDAR data for collision avoidance.
  • Subscribed Topics:
    • /control_command: Receives joystick movement commands.
    • /sensor_data: Receives LIDAR data.
  • Published Topics:
    • /cmd_vel: Sends modified speed commands for motors.
    • /rover_status: Sends rover status information.
  • Communication:
    • TCP/IP: Communicates with the base station.
    • I2C: Communicates with sensors on the Arduino Uno.

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benrover_sensors/sensor_node

  • Role: Retrieves and processes sensor data via I2C.
  • Published Topics:
    • /sensor_data: Sends sensor data (LIDAR) to the navigation node.
    • /temperature_data: Sends temperature sensor data (if applicable).
    • /distance_data: Sends distance sensor data (if applicable).
  • Communication:
    • I2C: Communicates with sensors.

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benrover_actuators/actuator_node

  • Role: Translates movement commands from the navigation node into motor and servo commands.
  • Services:
    • SetMotorSpeed: Modifies the speed of a specific motor.
    • SetServoPosition: Sets the position of a servo motor.
  • Communication:
    • PWM: Communicates with the Arduino Mega.

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benrover_energy_management/energy_management_node

  • Role: Monitors battery status and manages rover power consumption.
  • Subscribed Topics:
    • /battery_status: Receives battery status information from the sensor node.

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benrover_interface/interface_node

  • Role: Displays rover status information to the user (LCD screen or web interface).
  • Subscribed Topics:
    • /rover_data: Receives information to display from the navigation node or other nodes.
  • Role: Receives motor speed commands (via PWM) from the actuator node on the Raspberry Pi and controls the rover’s motors.
  • Communication:
    • PWM: Receives PWM signals from the actuator node.

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Communication Flow

Base Station to Rover

Base Station ↔ Navigation Node (Raspberry Pi): Wi-Fi or TCP/IP

Internal Rover Communication

  1. Navigation Node ↔ Sensor Node (Raspberry Pi): I2C
  2. Navigation Node ↔ Actuator Node (Raspberry Pi): I2C
  3. Actuator Node (Raspberry Pi) ↔ Arduino Mega: PWM

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Best Practices

Follow these best practices to ensure efficient implementation and debugging of the Benrover ROS architecture:
  1. Message and Service Definitions: Define clear ROS messages and services for each node and package to ensure efficient communication.
  2. Transformation System: Utilize the tf package to manage reference frames for the robot and base station.
  3. Visualization: Use rviz for visualizing the robot, sensors, obstacles, and environment maps.
  4. Debugging: Employ rosbag, rqt, rosnode, and rostopic for identifying and fixing errors.

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Key Points

Base Station

  • Serves as the central server
  • Manages communication and user interface
  • Joystick is an input device

Rover

  • Acts as a client
  • Connects to the base station
  • Receives commands and sends data

Communication

  • Wi-Fi and TCP/IP between base station and rover
  • I2C between Raspberry Pi and sensors/actuators
  • PWM for motor and servo control

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Want to use our ROS workspace?

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💻 Installation

  1. Installing ROS by following the instructions in the documentation: https://docs.ros.org/en/humble/Installation/Ubuntu-Install-Debs.html
  2. Install colcon to build packages 
    sudo apt install python3-colcon-common-extensions
  3. Clone the repository 
    git clone https://github.com/BenRover-24/rosws.git

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⚙️ Configuring environment

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    On Ubuntu

    If you don’t want to have to source the setup file every time you open a new shell, then you can add the command to your shell startup script: 
    gedit ~/bashrc
    In the file that opens, complete the following lines: 
    source /opt/ros/humble/setup.bash
source /usr/share/colcon_argcomplete/hook/colcon-argcomplete.bash
source /path/to/the/root/of/your/workspace/source install/local_setup.bash

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Build the workspace

 colcon build --symlink-install