Architecture

Setup

We are using ROS 2 Humble, for Ubuntu Jammy 22.04

• Install and configure git

  sudo apt-get install git
  git config --global user.name GITHUB_USERNAME
  git config --global user.email GITHUB_EMAIL
  

• Install ROS 2

  • https://docs.ros.org/en/humble/Installation/Ubuntu-Install-Debs.html

• Add ROS to bash

  • nano ~/.bashrc

    At the bottom add

    source /opt/ros/humble/setup.bash
    source ~/ros2_ws/install/setup.bash
    

    Restart the command line window to apply the .bashrc

• Install Colcon and Ninja for building

  • sudo apt install python3-colcon-common-extensions
    sudo apt-get install ninja-build
    

• Install rosdep for dependency management

  •  sudo apt-get install python3-rosdep
     sudo rosdep init
     sudo rosdep update
    

• Create a ros2 workspace at home and go to its src folder

  •   mkdir -p ~/ros2_ws/src
      cd ~/ros2_ws/src
    

• Clone this repository

  • git clone https://github.com/Esteb37/dextrous_hand

• Resolve dependencies

  •   cd ..
      rosdep install -i --from-path src --rosdistro humble -y
    

• Build from within ros2_ws

  • colcon build --packages-select dextrous_hand

• Test node

  • ros2 run dextrous_hand basic_node

    [INFO] [1728219147.878266379] [basic_node]: Hello, ROS 2 (Python)!
    

• Add pip

  • sudo apt install python3-pip

• Add Motor library

  •  cd
     git clone https://github.com/ROBOTIS-GIT/DynamixelSDK.git
     cd DynamixelSDK/python
     sudo python3 setup.py install
    

• Add teleop control library

  • pip install pynput

Running Teleop Control

• cd to your ros2_ws workspace

• colcon build

• Connect the motor controller

• Give access to the port

  sudo chmod 777 /dev/ttyUSB0 or sudo chmod 777 /dev/ttyUSB1

• Run hand node ros2 run dextrous_hand hand_node Make sure all motors show as connected

• In another window run teleop node ros2 run dextrous_hand teleop_node

• Control the motors with the keyboard

  • Select predefined configuration

    z = Home
    x = Grasp
    c = Rock
    v = Middle finger
    b = Peace sign
    n = Thumbs up
    m = Spock salute
    

  • Select the subsystem

    q = pinky
    w = ring
    e = middle
    r = index
    t = thumb
    y = wrist
    u = all fingers (no wrist)
    o = orientation
    p = position
    

  • Select the joint

    1 = ABD | wrist | position X | orientation roll
    2 = MCP | position Y | orientation pitch
    3 = PIP/DIP | position Z | orientation yaw
    

  • Control the joint

    l = add to angle
    k = substract from angle
    

Calibration

• Set all the fingers and wrist to the desired zero position
• Run calibration_node
• If motor direction also needs to be calibrated
  • Select y when prompted
  • Flex all the finger joints towards the inside of the palm and the wrist forward.
  • Press enter

Adding files

Nodes

• Add the .py file at /src
• In setup.py

   entry_points={
       'console_scripts': [
           'basic_node = src.basic_node:main',
           'your_node = src.your_node:main', <-- Add node here
       ],
   },
  

Modules

• Just add the .py file at /dextrous_hand

  • When importing, do not forget to append dextrous_hand

    import dextrous_hand.my_module as my_module

File Structure

• /src - Python node files
• /dextrous_hand - Python module files
• /launch - ROS Launch files
• /test - Any code that does not correspond to a node (i.e. test code and experiments)
• /data - Images, text-files, ML models etc

Building With Symlink

• Open your bashrc and add alias colcon_build='colcon build --symlink-install'
• source bashrc
• Now you can build once with colcon_build.
• Build everytime you add a new file.
• No need to rebuild for every change made in a Python file.
• Need to rebuild for every change made in a C++ file.

SetupTools Error

• If you have the setup tools error, do the following in a new terminal:pip list | grep setuptools
• You should see that your setuptools version is > 58.2.0
• Downgrade the version : pip install --upgrade pip setuptools==58.2.0
• pip list | grep setuptools to check if downgrade successfull
• You should not have this error again