The TurtleBot 4 is a ROS2-based mobile robot designed for education and research, capable of mapping its surroundings, autonomous navigation, and running AI models on its camera. It comes in two models: TurtleBot 4 and TurtleBot 4 Lite. Both models are built on an iRobot® Create® 3 mobile base and feature a Raspberry Pi 4 running ROS 2, an OAK-D stereo camera (OAK-D-Lite for the Lite model, OAK-D-Pro for the standard model), and a 2D LiDAR.

Function Description:

The TurtleBot 4 serves as an open-source robotics platform, providing an out-of-the-box development and learning experience. It is designed for tasks such as:

Mapping: Generating 2D maps of its environment using the RPLIDAR A1M8.
Navigation: Autonomous movement within mapped environments using the Nav2 stack, including features like navigating to a pose, following waypoints, and docking.
AI Applications: Running computer vision applications, object tracking, and AI models on its OAK-D camera.
User Interaction: Features a User Interface (UI) board with status LEDs, user buttons, and a 128x64 user display for direct control and feedback.
Simulation: Can be simulated in Ignition Gazebo, allowing users to test robot behavior without a physical robot.

Important Technical Specifications:

General:

Base Platform: iRobot® Create® 3
On-board Computer: Raspberry Pi 4B 4GB
Operating System: Ubuntu 20.04 LTS (Focal Fossa) with ROS2 Galactic
Maximum Linear Velocity: 0.31 m/s in safe mode, 0.46 m/s without safe mode
Maximum Angular Velocity: 1.90 rad/s
Operation Time: 2h 30m - 4h (depending on load)
Charging Time: 2h 30m

TurtleBot 4 (Standard Model):

Size (L x W x H): 342 x 339 x 351 mm
Weight: 3945 g
Maximum Payload: 9 kg
Lidar: RPLIDAR A1M8 (360-degree Laser Range Scanner with 12m range)
Camera: OAK-D-Pro (higher resolution OV9282 stereo sensors, IR laser dot projector, IR illumination LED for low-light performance)
Bluetooth Controller: Included (TurtleBot 4 Controller)
User Interface (UI) Board: Features status and user LEDs, user buttons, 128x64 user display, 4 USB 3.0 (Type C) ports, additional power ports, and Raspberry Pi pins.

TurtleBot 4 Lite (Barebones Model):

Size (L x W x H): 342 x 339 x 192 mm
Weight: 3270 g
Maximum Payload: 9 kg
Lidar: RPLIDAR A1M8
Camera: OAK-D-Lite (4K IMX214 color sensor, OV7251 stereo sensors)
Bluetooth Controller: Not Included

Power Budget (Nominal Consumption):

Total Available Power: 28.8W
TurtleBot 4 Total Power Draw: 15W (Remaining Power: 13.8W)
TurtleBot 4 Lite Total Power Draw: 10.6W (Remaining Power: 18.2W)
USB-C Ports: 4 ports, total 3A current available, each port current limited to 3A (shared dynamically). On REV 2 board, port 4 supplies 3A, others 2.6A +/- 0.1A.
User Power Ports (UI Board): 3.3V (250mA), 5V (500mA), 12V (300mA), VBAT (300mA).

Usage Features:

Quick Start: Powering on by placing on the charging dock, powering off by removing from dock and holding the Power button.
WiFi Setup: Raspberry Pi enters AP mode on first boot for easy WiFi configuration via SSH.
Controller Setup: TurtleBot 4 comes with a pre-paired Bluetooth controller; manual pairing instructions are provided.
Software Updates: Firmware for both the Create® 3 and Raspberry Pi can be updated over WiFi or USB-C. Debian and source packages can also be updated.
Driving the Robot: Supports keyboard teleoperation via teleop_twist_keyboard and joystick teleoperation via a Bluetooth controller. Velocity limits can be adjusted.
ROS2 Actions: Utilizes Create® 3 actions like DriveDistance, DriveArc, and RotateAngle for precise movement commands.
Navigation Stack (Nav2): Uses Nav2 for advanced navigation, including setting goal poses, navigating through poses, and following waypoints.
SLAM: Supports both synchronous (high accuracy, high processing) and asynchronous (lower processing, reduced accuracy) SLAM for map generation.
Rviz2 Visualization: Provides a graphical interface for viewing robot models, sensor data (LaserScan, Camera, TF), and navigation progress.
User Interface (HMI): The TurtleBot 4's UI board features a 128x64 OLED display and buttons for menu control (Scroll Up, Down, Select, Back, Help). User LEDs can be programmed.
Payloads: Designed to accommodate additional sensors and accessories on its top integration plate or within the base unit. Instructions for mechanical modifications to support heavier payloads (over 9kg) are provided, including adding a caster wheel and lowering the payload height.

Maintenance Features:

Firmware Updates: Regular updates for Create® 3 and Raspberry Pi are recommended for bug fixes and improvements.
Software Management: Debian packages can be updated using apt, and source packages can be updated by pulling changes from Git repositories and rebuilding.
Raspberry Pi Image Installation: Instructions are provided for installing the latest Raspberry Pi image, including backing up the current image and flashing a new one.
Diagnostics: The turtlebot4_diagnostics package provides tools (rqt_robot_monitor) to monitor robot topics, ensuring data is published at expected frequencies and identifying errors or warnings.
ROS2 Tests: Includes system test scripts (turtlebot4_tests) to verify basic functionality of the light ring, buttons, LEDs, display, and docking capabilities, useful for troubleshooting.
Troubleshooting Guide: Addresses common issues such as the Raspberry Pi access point not being visible, ros2: command not found errors, and Create® 3 topics not being visible.
Mechanical Access: Detailed instructions for removing the top integration plate, PCBA, and Create® 3 integration plate and shell for internal access and modifications.
Battery Management: Recommended not to drain the robot below 20% VBAT voltage to prevent sharp decline.

CLEARPATH Turtlebot4 - Page 149

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