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Ubuntu-driven TurtleBot gets a major rev with a Pi or Joule in the driver’s seat

Jun 9, 2017 — by Eric Brown — 1,689 views
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A new TurtleBot3 rev of the open source, Ubuntu/ROS-based robot kit is available in “Burger” and “Waffle” models with an RPi 3 or Intel Joule, respectively.

The “world’s most popular open source robot for education and research” has received a major upgrade with two modular TurtleBot3 models from Open Robotics that run Linux and Robot Operating System (ROS) on a Raspberry Pi 3 (“Burger”) SBC or Intel Joule COM (“Waffle”). The dual-wheel Turtlebot 3 is smaller, cheaper, simpler, and more powerful than the discontinued TurtleBot 1 and still available, Clearpath Robotics built TurtleBot 2. The latter runs ROS via Linux or Windows on an Intel Core i3-4010U based netbook instead of a compute board.

TurtleBot3 Burger (left) and TurtleBot3 Waffle
(click image to enlarge)

The TurtleBot3 was built by Robotis, and the project is maintained by Open Robotics, a taxable subsidiary of the Open Source Robotics Foundation (OSRF). Open Robotics also maintains the open source ROS stack that runs on the other TurtleBots as well as scores of other robots and drones. Other collaborators include Intel, which contributed the Intel Joule module and Intel RealSense cameras, and Onshape, which supplies its “full-cloud” 3D CAD editor for working with the TurtleBot’s open source 3D CAD files.

The TurtleBot3 is “the most affordable robot among the SLAM-able mobile robots equipped with a general 360-degree LiDAR,” says Open Robotics. The TurtleBot3 Burger kit sells for $549, including the Raspberry Pi 3, and the larger TurtleBot3 Waffle kit sells for $1,799 including the Intel Joule. The TurtleBot2 sells for $2,115 fully assembled.

TurtleBot3 Burger (left) and TurtleBot3 Waffle details views
(click images to enlarge)

SLAM (simultaneous localization and mapping) is the type of algorithm required to map an unknown environment while simultaneously keeping track one’s position within it. LiDAR is the advanced pulsed laser location technology that enables SLAM. Both models integrate 360-degree HLS-LFCD LDS planar LiDAR systems, enabling autonomous navigation. The Waffle’s Joule module also offers Intel’s RealSense depth-finding camera, providing an alternative visual approach to SLAM.

Robotis HLS-LFCD LDS LiDAR system (left) and a self-generated Burger SLAM navigaton map
(click images to enlarge)

In addition to leveraging LiDAR and RealSense for location, the TurtleBot3 gains precise spatial data by integrating a pair of Robotis Dynamixel smart actuators in the two sprocket wheel joints. The actuators can be operated by one of four operating modes using the Dymamixel XL420 model on the Burger, or six modes using the Dynamixel XM430 model on the Waffle. The Dynamixels provide velocity control for the wheels and torque or position control for the joints.

OpenCR control over Dynamixel actuators
(click image to enlarge)

Both TurtleBot3 models run on a Robotis OpenCR board for controlling the Dynamixels and sensors, such as the board’s built-in IMU, as well as touch, IR, color, and others. The board can run Arduino IDE code on its 216MHz, 32-bit Cortex-M7 STM32F7 MCU. The high-end STM32F7 includes an FPU, and is said to offer 462 DMIPS performance.

OpenCR control board detail view
(click image to enlarge)

The open spec OpenCR control board has 18 GPIO pins, 32 Arduino pins, and 3.3V, 5V, and 12V power supplies. There are three RS485 and three TTL interfaces for controlling the Dynamixels. Other peripherals include three UART, five ADC, four 5-pin OLLO, and single CAN, SPI, and I2C connections. A micro-USB port lets you connect with a PC, and various LEDs and buttons are available.

The TurtleBot3 is further equipped with an 1800mAh battery and a 100-240V, AC 50/60Hz power adapter. Tools, cables, and other parts are also available. Fully assembled, the 138 x 178 x 192mm (L/W/H) TurtleBot3 Burger model is about a quarter of the size of the TurtleBot2, and the TurtleBot3 Waffle measures 281 x 306 x 141mm.

TurtleBot3 mechanical and performance specs
(click image to enlarge)

TurtleBot3 can be teleoperated by an Android app, as well as wireless devices such as a keyboard, PS3 and XBOX 360 joysticks, the Robotis RC100 controller, the LEAP Motion controller, and more. The open source navigation software runs on Ubuntu 16.04.2 with ROS Kinetic. An Ubuntu Insights announcement of the robot notes that both the Raspberry Pi and Joule support Ubuntu Core, giving robot designers “security, transactional updates, and even an app store.”

According to a hands-on story last month in IEEE Spectrum, assembling the Burger took “an hour or two,” while the Waffle took about four hours due to additional parts, including 192 screws. The software setup of ROS on the Burger’s Raspberry Pi took another “few hours,” while the setup on the Joule took much longer due to the need to update the BIOS with the help of a Windows PC. Overall, however, hardware and setup were said to be well documented.

The modular, completely open source TurtleBot3 design, which includes open 3D CAD files, as well as schematics, PCB Gerber, and BOM, is available with optional parts. These include different sensor and chassis components, as well as a variety of Robotis arms and grippers. With a bit of work, you could even swap out the Pi or Joule for another compute board.

Raspberry Pi 3 (left) and Intel Joule
(click images to enlarge)

The Raspberry Pi 3 SBC runs on a Broadcom BCM2837 with four 1.2GHz Cortex-A53 cores and a VideoCore IV GPU. Other features include 1GB RAM, Fast Ethernet, WiFi/Bluetooth, four USB ports, and a 40-pin expansion interface.

The Intel Joule 570x — the higher-end of the two Joule computer-on-modules — provides a quad-core Atom T5700 SoC (1.7GHz clock; 2.4GHz burst) similar to Intel’s Apollo Lake models. The Joule ships with up to 4GB RAM and 16GB eMMC, plus WiFi/Bluetooth, 4K video, CSI/DSI, GPIO, USB, and UART I/O. The module offers built-in support for Intel RealSense.

Assembling the TurtleBot3 Burger

Further information

The Robotis built, Open Robotics TurtleBot3 Burger and TurtleBot3 Waffle are available for $549 and $1,799, respectively, at the TurtleBot3 shopping page. More information may be found on the TurtleBot community site.

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