rolling_fingers_gripper

Control nodes and examples for the Rolling Fingers gripper (3- and 4-finger variants). The nodes use the local wrapper library dynamixel_ros2 which in turn uses the Dynamixel SDK.

This README explains required dependencies, how to build the package in a workspace, and how to run the example nodes.

Dependencies

This repo uses the dynamixel_ros2.

To be able to use, you'll need to do the following:

• Install the dynamixel SDK

sudo apt-get install ros-$ROS_DISTRO-dynamixel-sdk

• Create a ros2 workspace where you will include this repository
• In yout src folder, clone the dynamixel_ros2:

git clone git@github.com:jmgandarias/dynamixel_ros2.git

• Then, clone the rolling_fingers_gripper repository

git clone git@github.com:TaISLab/rolling_fingers_gripper.git

Requirements

• Ubuntu 22.04
• ROS 2 Humble
• Dynamixel SDK (ROS package)

  sudo apt update
  sudo apt install ros-$ROS_DISTRO-dynamixel-sdk

Quick install (recommended)

1. Create or go to a workspace:

   mkdir -p ~/ros/rolling_fingers_ws/src
   cd ~/ros/rolling_fingers_ws/src

2. Clone required repositories into src/:

   # dynamixel wrapper library used by these nodes
   git clone git@github.com:jmgandarias/dynamixel_ros2.git
   
   # this repository (rolling_fingers_gripper)
   git clone git@github.com:TaISLab/rolling_fingers_gripper.git

3. Build the workspace and source the overlay:

   cd ~/ros/rolling_fingers_ws
   colcon build
   source install/setup.bash

Running the example nodes

After sourcing the workspace overlay, run one of the example executables:

• 3-finger node:

  ros2 run rolling_fingers_gripper rolling_3_fingers

• 4-finger node:

  ros2 run rolling_fingers_gripper rolling_4_fingers

If you add launch files, use ros2 launch <package> <launchfile>.

Configuration

• Serial device: ensure the node can access your serial device (e.g. /dev/ttyUSB0). Add your user to the dialout group if needed:

  sudo usermod -a -G dialout $USER
  # then re-login or open a new shell

• Motor IDs, baud rate and port are configured in the node source files or via parameters if exposed — check src/rolling_*_fingers.cpp for current defaults.

Using the dynamixel_ros2 library from another package

If you want to use the wrapper library directly from another ROS 2 package:

• package.xml

  <build_depend>dynamixel_ros2</build_depend>
  <exec_depend>dynamixel_ros2</exec_depend>
  <build_depend>dynamixel_sdk</build_depend>
  <exec_depend>dynamixel_sdk</exec_depend>

• CMakeLists.txt (minimal example)

  find_package(dynamixel_ros2 REQUIRED)
  find_package(dynamixel_sdk REQUIRED)
  
  add_executable(my_node src/my_node.cpp)
  ament_target_dependencies(my_node rclcpp dynamixel_ros2 dynamixel_sdk)
  
  # link exported target if provided by the library
  if(TARGET dynamixel_ros2_lib)
    target_link_libraries(my_node dynamixel_ros2_lib)
  endif()

Build your package after sourcing the workspace install overlay that contains dynamixel_ros2.

Troubleshooting

• Linker errors (undefined references):

  • Make sure you built dynamixel_ros2 and sourced the workspace install/setup.bash.
  • Verify library presence: ls -l install/dynamixel_ros2/lib or /opt/ros/$ROS_DISTRO/lib.

• AMENT_PREFIX_PATH / CMAKE_PREFIX_PATH warnings:

  • These indicate a stale overlay in your environment. Re-source the correct install/setup.bash or remove old overlay entries.

• Serial port permission issues:

  • Add user to dialout group or run node with appropriate permissions.

Development notes

• Example nodes are minimal for demonstration. Add parameter support, safety checks and launch files for production use.
• If you change the exported CMake target name in dynamixel_ros2, update dependent packages accordingly.

License

This repository uses the dynamixel_ros2 library which is licensed under the GNU GPLv3 (see src/dynamixel_ros2/LICENSE). Ensure you follow the GPLv3 obligations when redistributing derived works.