Authors: <Jeongeun Kim> Email: jeongeun9988@gmail.com, <Nicolas Kosanovic> Email: kosanovi@unlv.nevada.edu

Mentors: <Akshay Dave> Email: davea1@unlv.nevada.edu, <Jean Chagas Vaz> Email: chagasva@unlv.nevada.edu

Date: Last Modified on <11/21/21>

Keywords: <DARwIn-OP, DARwIn++, Humanoids, Tutorial, how to, step-by-step, Robotics, Upgrade>

[A picture of DARwIn++ next to DARwIn-OP]

This tutorial details the process of upgrading DARwIn-OP (on the left in the picture above), a famous miniature humanoid robot, to DARwIn++ (on the right in the picture above), a modernized version of DARwIn-OP. Since DARwIn-OP has been discontinued by its manufacturer, ROBOTIS, DARwIn-OP’s technological hardware has become obsolete.

DARwIn++ serves to breathe new life into the platform by replacing DARwIn-OP’s old management controller with a newer, more powerful piece of hardware (the NVIDIA Jetson Nano) to increase DARwIn++’s capabilities and potentially “future-proof” the hardware for years to come.

This tutorial details the process of replacing DARwIn-OP’s old computer (the ATOM Z530) with the NVIDIA Jetson Nano, the installation of Ubuntu 18.04 onto the Jetson Nano.

This tutorial takes approximately 2 hours to complete.

This tutorial’s motivation is to upgrade DARwIn-OP. This tutorial assumes that its readers have the following background and interests:

- Soldering
- Ubuntu
- Humanoids

The rest of this tutorial is presented as follows:

- Parts List and Sources
- Construction
- Final Words

US-based vendors that sell the materials used in this tutorial include Amazon, Raspberry Pi, and Aliexpress.
To complete this tutorial, you will need the following:

This section gives step-by-step instructions, along with photos, to upgrade DARwIn-OP to DARwIn++.

Note: This tutorial outlines the process of replacing the ATOM Z530 (DARwIn-OP 1’s original computer) with the NVIDIA Jetson Nano. The ATOM Z530 board is NOT upgraded in this tutorial. Also note that this tutorial works for DARwIn-OP 1 and DARwIn-OP 2, with the latter robot requiring an additional step.

i) Remove the Nylon harness from the top of the backside of DARwIn’s torso. To aid in screw management, it can help to put a piece of double-sided tape on a piece of paper and write what each screw is for. This ensures you know where the screws are, and that you can’t lose them!

ii) Remove the Battery from DARwIn.

iii) Remove the battery compartment from the bottom of DARwIn’s torso. This should cause DARwIn’s entire lower torso to come off, as seen in the following pictures:

Figure X: DARwIn with its battery compartment and Front and Back Plates removed.

NOTE: The steps listed here are reminiscent of what’s seen in this YouTube video of an “Exploratory Surgery of DARwIn 2.0”. This may help in understanding how to disassemble DARwIn.

Link: https://www.youtube.com/watch?v=c4H3XUlOcJs&ab_channel=ChrisI-B

i) Remove the screws from the front plastic covering (this plastic covering is called the “Front Plate”). Gently remove the Front Plate. Note that the Front Plate is connected to DARwIn’s torso via a speaker wire. Make sure to disconnect the speaker wire before taking DARwIn’s Front Plate off entirely.

ii) Remove the screws from DARwIn’s back plastic covering (this plastic covering is called the “Back Plate”). Gently remove the Back Plate. Note that the Back Plate is connected to DARwIn’s torso via 2 wires. Make sure to disconnect the wires before taking off DARwIn’s Back Plate entirely.

iii) Unscrew the screws that connect the “top part” of DARwIn’s torso to the “bottom part” of DARwIn’s torso (see Figure X). Note: There are 3 screws on the front, and 3 screws on the back.

Figure X: The “Upper” and “Lower” torso of DARwIn. DARwIn’s “Upper Torso” includes the plate with DARwIn’s shoulder and neck Dynamixels. DARwIn’s “Lower Torso” Includes the plate with the CM730 and the ATOM Z530 CPU.

iv) Disconnect the 5 TTL (Transistor-Transistor Logic) cables from the CM730 board (see Figure X). Label the cables “Cable 1” through “Cable 5”, as done in Figure X below to avoid confusion.

v) Expose DARwIn’s chest. My DARwIn had a zip-tie on its chest, so I cut it off.

vi) Disconnect all of the cables connecting the top and bottom portions of DARwIn’s torso. Label which cable is which to avoid confusion when reassembling DARwIn.

vii) Remove the ATOM Z530 from DARwIn.

To connect the new main computer (the NVIDIA Jetson Nano) to the DARwIn’s Head Camera/Subcontrollers, a connection via USB will be established. While both the CM730 Board and the Head Camera follow the USB protocol, the two components use different USB connection ports. For this reason, the Head Camera will need to be updated to utilize the USB interface.

i) Prepare a USB board. Note: if you don’t have a USB board, one can do the following:

- Get a USB cable from an unused peripheral (like an old mouse/keyboard). You can cut the USB wire off of the peripheral (one can also use the Male-to-Male USB cable included in the Bill of Materials (“BOM”)).

- You should see 4 wires and a tin-foil-esque film. Strip all four wires and label them “Wire 1”, “Wire 2”, “Wire 3”, and “Wire 4”. Note: not all of these wires are made equally. Errors can cause massive damage, so don’t rely solely on the colors of the wires!

- Ensure that you can discern which wire is which by putting a multimeter to continuity mode and placing the two prongs on two points of the wire. If continuity is achieved, you have completed the preparation of a USB board!

ii) Solder the 4 wires found in the USB cable to the 4 pin connector as done in Figures X and X.

Figure X: The USB Port

Figure X: The USB Board

iii) Once you are finished soldering, you should have a USB Board that looks like Figure 3.

Figure 3: The Completed USB Board

iv) To check if the newly-made USB Board works, connect the USB cable into your computer and run the “VLC Media Player” program.

v) Go to the top left corner to the “Media” dropdown menu.

vi) In “Media”, click on “Open Capture Device”.

vii) Under the “Capture Device” tab of the “Open Media” window, click on the dropdown menu of “Video device name” and select any one of the devices, and then hit “Play” on the “Open Media” window. Note: there may not be a specific name for the USB Board, so you may have to go through all of the names in the list. You can see Figures 4 - 8 for a visual walkthrough of this process.

Figure 4:

Figure 5:

Figure 6:

Figure 7:

Figure 8:

This step details the process of Installing an NVIDIA Jetson Nano into DARwIn and setting up the NVIDIA Jetson Nano.

This section is currently under construction.

These steps follow the <Getting Started with Jetson Nano Developer Kit> tutorial.
URL: https://developer.nvidia.com/embedded/learn/get-started-jetson-nano-devkit
The following instructions guide you through the process of installing Linux (specifically Ubuntu 18.04) onto the NVIDIA Jetson Nano.

i) Ensure that you have the following materials:
- A 32 GB UHS-1 microSD Card
- A good Barrel-Jack-ended power supply capable of providing 5V⎓4A.

ii) Download the Jetson Nano Developer Kit SD Card Image (https://developer.nvidia.com/jetson-nano-sd-card-image). Assuming you’re running Ubuntu download and launch Balena Etcher (https://www.balena.io/etcher/). If you’re not using Ubuntu, go to the “Get Started with Jetson Nano Developer Kit” link above and follow their tutorial for setting up a Jetson Nano with a different operating system.

iii) Click on “Select Image” and choose the zipped SD card image file downloaded in step ii).

iv) Insert the microSD card into your computer. BalenaEtcher should automatically recognize it as the target device. If not, select it manually.

v) Click “Flash!” You may need to enter your Username and Password for BalenaEtcher to continue.

vi) After BalenaEtcher is done writing the image to the microSD card, eject the microSD card from the files app and then take the microSD card out of your computer.

vii) Insert the microSD card into the NVIDIA Jetson Nano, and then boot into the NVIDIA Jetson Nano. Note that if you’re powering the NVIDIA Jetson Nano with a barrel jack connector, you must add a jumper cable to the D63 pin.

viii) Go through the default instructions and set up the password (e.g. “DASL1234”).

ix) Boot up into the NVIDIA Jetson Nano for the first time, and enter in the following 3 lines into the terminal (you can open the terminal by pressing ctrl+alt+t):

sudo jetson_clocks
sudo apt-get update
sudo apt-get upgrade

Note: these instructions are for the installation of ROS Melodic on Ubuntu 18.04. This tutorial will assume that you already know how to download Ubuntu. If you don’t, see the following URL:http://wiki.ros.org/melodic/Installation/Ubuntu.

i) Open the Terminal (ctrl+alt+t) and paste the following command lines one at a time, step-by-step.

sudo sh -c 'echo "deb http://packages.ros.org/ros/ubuntu $(lsb_release -sc) main" > /etc/apt/sources.list.d/ros-latest.list'
sudo apt-key adv --keyserver 'hkp://keyserver.ubuntu.com:80' -recv-key C1CF6E31E6BADE8868B172B4F42ED6FBAB17C654
sudo apt update
sudo apt install ros-melodic-desktop-full
echo "source /opt/ros/melodic/setup.bash" >> ~/.bashrc
source ~/.bashrc
sudo apt install python-rosdep python-rosinstall python-rosinstall-generator python-wstool build-essential
sudo apt install python-rosdep
sudo rosdep init
rosdep update
source  /opt/ros/melodic/setup.bash
mkdir -p ~/catkin_ws/src
cd ~/catkin_ws/
catkin_make
sudo reboot

Open the Terminal again (ctrl+alt+t), and paste the following command lines one at a time, step-by-step.

sudo reboot 
sudo apt update && sudo apt install -y cmake g++ wget unzip
wget -O opencv.zip https://github.com/opencv/opencv/archive/master.zip
wget -O opencv_contrib.zip https://github.com/opencv/opencv_contrib/archive/master.zip
unzip opencv.zip
unzip opencv_contrib.zip
mkdir -p build && cd build
cmake -DOPENCV_EXTRA_MODULES_PATH=../opencv_contrib-master/modules ../opencv-master
cmake --build .

i) When booted into Ubuntu, search for “additional drivers” in the search bar. Navigate to “additional drivers”, and select “UBUNTU Software” and “enable source code”. Make sure the “download from” field is set to “main server”.

ii) Open the terminal (ctrl+alt+t), and paste the following commands one at a time, step-by-step.

sudo apt-get install libncurses5-dev libncursesw5-dev
sudo apt-get install ros-melodic-sbpl
sudo apt-get install ros-melodic-map-server
sudo apt-get install ros-melodic-nav-msgs
sudo apt-get install ros-melodic-octomap
sudo apt-get install ros-melodic-octomap-msgs
sudo apt-get install ros-melodic-octomap-ros
sudo apt-get install ros-melodic-octomap-server
sudo apt-get install ros-melodic-gazebo-ros
cd ~/catkin_ws/src
git clone https://github.com/ahornung/humanoid_msgs.git
git clone https://github.com/ROBOTIS-GIT/DynamixelSDK
git clone https://github.com/ROBOTIS-GIT/ROBOTIS-Framework
git clone https://github.com/ROBOTIS-GIT/ROBOTIS-Framework-msgs
git clone https://github.com/ROBOTIS-GIT/ROBOTIS-Math
git clone https://github.com/ROBOTIS-GIT/ROBOTIS-OP2
git clone https://github.com/ROBOTIS-GIT/ROBOTIS-OP2-Common
git clone https://github.com/ROBOTIS-GIT/ROBOTIS-OP3
git clone https://github.com/ROBOTIS-GIT/ROBOTIS-OP3-msgs
git clone https://github.com/ROBOTIS-GIT/ROBOTIS-OP3-Tools
git clone https://github.com/HumaRobotics/darwin_gazebo.git
git clone https://github.com/HumaRobotics/darwin_description
git clone https://github.com/HumaRobotics/darwin_control
cd ~/catkin_ws

iii) Navigate to “/catkin_ws/src/ROBOTIS-OP3-Tools” and delete the “op3_action_editor” folder. (Note: this step is VERY important)

iv) After deleting the “op3_action_editor”, open up the terminal (ctrl+alt+t), and paste in the following command:

:$ catkin_make

i) Open the terminal (ctrl+alt+t), and paste the following commands one at a time, step-by-step.

sudo bash
source catkin_ws/devel/setup.bash
sudo chmod 666 /dev/ttyUSB0
roslaunch op2_manager op2_manager.launch

ii) Open a new terminal (ctrl+alt+t) next to the old terminal and paste the following commands one at a time, step-by-step.

sudo bash
source catkin_ws/devel/setup.bash
sudo chmod 666 /dev/ttyUSB0
roslaunch op2_gui_demo op2_demo.launch

Note that the following website was used as a major reference for this step: URL: https://bit.ly/3nxgfGM The steps outlined in this portion of the tutorial merely summarize what Bharath Sudharsan describes in his medium article.

i) Open the Terminal (ctrl+alt+t) and paste the following:

sudo gedit /usr/share/glib-2.0/schemas/org.gnome.Vino.gschema.xml

ii) Doing the above should have opened a text editor up. Paste the code from the box below into the file, between “</schema>” and “</schemalist>”. See Figure X to see this done.

<key name='enabled' type='b'>
<summary>Enable remote access to the desktop</summary>
<description>
If true, allows remote access to the desktop via the RFB protocol. Users on remote machines may then connect to the desktop using a VNC viewer.
</description>
<default>true</default>
</key>

iii) After pasting the code found in ii), save and exit out of that window.

iv) Open another terminal (ctrl+alt+t), and paste the following:

sudo glib-compile-schemas /usr/share/glib-2.0/schemas

v) Select “Allow other users to view your desktop” and “Allow other users to control your desktop”. Make sure that “You must confirm each access to this machine” is deselected. Lastly, select the “Require the user to enter this password” box and enter in a password for the VNC session.

i) Open “Startup Applications” in Ubuntu. Click on “Add”. Type “Vino” in the search box, and then type “/usr/lib/vino/vino-server” into the command box. After doing so, save and close the app.

ii) Open the terminal (ctrl+alt+t), and paste in the following commands:

$ gsettings set org.gnome.Vino require-encryption false
$ gsettings set org.gnome.Vino prompt-enabled false

iii) Reboot.

i) Open the terminal (ctrl+alt+t) and paste the following to find the IP address.

$ ifconfig

ii) Paste the following into the terminal to check if the VNC server is running.

$ ps -ef|grep vnc

iii) Connect to the Jetson Nano using any VNC Client. The next steps assume that the VNC Client “Remmina” is used.

iv) Open Remmina. Click the “Add” button, and select “VNC” as the protocol.

v) Click the “…” button to automatically scan. Once the Jetson NANO appears, click on it, and enter your password. Lastly, hit “Connect”.

Note that the following was used as a major reference for this step: URL: http://wiki.ros.org/joy Warning: The link above is is for ROS Indigo, not ROS Melodic. Since this tutorial featured using ROS Melodic on Ubuntu 18.04, the following steps will act to translate the above link to ROS Melodic.

i) Start by opening the terminal (ctrl+alt+t) and pasting the following code to download a package:

$ sudo apt-get install ros-melodic-joy

ii) Connect your joystick to your laptop. Check if Linux recognizes the joystick by pasting the following command into the terminal:

$ ls /dev/input/ 

Joystick devices are referred to as “jsX”, where the “X” is a number. My joystick was recognized as “js0”. Now, let’s check if the joystick actually works.

iii) Open a new terminal (ctrl+alt+t) and paste the following code:

$ sudo jstest /dev/input/jsX

Try moving the joystick around now. Changes in the data output on the screen indicate that the joystick’s inputs are being read!

iv) Next, the ROS node needs to access the joystick. This can be done by first opening a new terminal (ctrl+alt+t) and pasting the following code to list the permissions of the joystick:

$ ls -l /dev/input/jsX

This should yield an output of the form:

“crw-rw-XX- 1 root dialout 188, 0 2009-08-14 12:04 /dev/input/jsX”

Where the “XX” in the “crw-rw”xx- 1” varies.

If “XX” is “rw”: the joystick device (“js”) was configured properly. If “XX” is “–”: the joystick device was not configured properly. You’ll need to paste the following code in a new terminal (ctrl+alt+t):

$ sudo chmod a+rw /dev/input/jsX

v) We will need to start a new ROS Joy node to obtain the data published by the Joystick. Assuming the joystick device was recognized as “js0”, paste the following code into a terminal (ctrl+alt+t), line-by-line.

$ roscore
$ rosparam set joy_node/dev “/dev/input/jsX”

vi) Next, start the ROS Joy node by pasting the following code into the terminal (ctrl+alt+t):

$ rosrun joy joy_node

vii) Lastly, run a new terminal (ctrl+alt+t) simultaneously to be able to see the data stream from the joystick.

$ rostopic echo joy

As you move the joystick around, you should be able to see something like:

Axes: (0.0, 0.0, 0.0, 0.0, 0.0) Buttons: (0, 0, 0, 0, 0)

This step details the process of setting up DARwIn++ (following the DARwIn++ “Hello World” tutorial video linked below) and the process of using the buttons on the joystick to control DARwIn++. Note that this tutorial was written in the context of using Arcade DARwIn.

The DARwIn++ controlling process begins with the setting up of DARwIn++, done as follows:

i) Plug in a keyboard (USB), a mouse (USB), and a monitor (HDMI) into DARwIn++. Then plug in the 5V 4A power cord into DARwIn++.

ii) Switch DARwIn++ ON and look at the monitor as it boots up.

iii) Once the NVIDIA Jetson Nano boots up fully, connect to the WiFi Network “HUBO 5G”.

iv) Open a new terminal and input the following commands:

sudo bash
source catkin_ws/devel/setup.bash
sudo chmod 666 /dev/ttyUSB0
roslaunch op2_manager op2_manager.launch

After inputting the final command (the “roslaunch” command), the screen will print out information about dynamixels 1-20. After that, DARwIn++ will move to a prepatory position before entering a sitting position (the “initial position” of DARwIn++). Then swap to the Controlling Station (laptop).

v) Boot up the Controlling Station and open a new terminal (in the Controlling Station). Then input the following code:

source catkin_ws/devel/setup.bash
ls -l /dev/input/js0
sudo chmod a+rw/dev/input/js0
rosparam set joy_node/dev "/dev/input/js0"
rosrun joy joy_node

vi) After inputting the code, go back to the NVIDIA Jetson Nano monitor and open a new terminal. Then, input the following code to the new NVIDIA Jetson Nano terminal:

source catkin_ws/devel/setup.bash
rosrun grace_joy listener.py

vii) Push each button on the Joystick and watch as DARwIn++ listens to your commands! :)

Dismantling the DARwIn OP2 https://www.youtube.com/watch?v=c4H3XUlOcJs

DARwIn OP DARwIn OP - Getting started https://emanual.robotis.com/docs/en/platform/op/getting_started/

DARwIn OP 2 - Getting Started https://emanual.robotis.com/docs/en/platform/op2/getting_started/

Writing a Teleoperation Node for a Linux-Supported Joystick http://wiki.ros.org/joy/Tutorials/WritingTeleopNode

DARwIn-OP DASL WIKI https://www.daslhub.org/unlv/wiki/doku.php?id=darwin_op

While upgrading DARwIn-OP to DARwIn++ may seem daunting, the inherently cost-prohibitive pricing of new robots is damaging to novices interested in the industry. By upgrading obsolete humanoids to modern standards, the field of humanoid robotics becomes vastly more accessible, allowing for many more people to participate and advance the field.