SO-100 Robot Arm ROS2 Package

This package provides ROS2 support for the SO-100 robot arm, available in 5-DOF configuration. It is based on the open-source 3D printable SO-ARM100 project by The Robot Studio. This implementation includes URDF models, Gazebo simulation support, and MoveIt2 integration.

The original ROS1 implementation can be found at: https://github.com/TheRobotStudio/SO-ARM100

Features

• Robot arm URDF models
  • 5-DOF configuration with gripper
• Gazebo Harmonic simulation support
• ROS2 Control integration
  • Joint trajectory controller
  • Gripper action controller
• MoveIt2 motion planning capabilities (In Progress)
  • Basic configuration generated
  • Integration with Gazebo pending
  • Motion planning testing pending

Prerequisites

ROS2 and Dependencies

• ROS2 Humble
• Gazebo Garden
• MoveIt2
• ros2_control
• gz_ros2_control

Hardware Requirements

For using the physical robot:

• SO-ARM-100 robot arm (5-DOF)
• Feetech SMS/STS series servos
• USB-to-Serial converter (CH340 chip)

• so_arm_100_hardware package — install one of the following:

  Option A — apt (ROS 2 Jazzy):

  sudo apt install ros-jazzy-so-arm-100-hardware
  

Option B — from source:

  cd ~/ros2_ws/src
  git clone git@github.com:brukg/so_arm_100_hardware.git
  cd ~/ros2_ws
  colcon build --packages-select so_arm_100_hardware
  source install/setup.bash
  

Calibrating the Arm

The hardware interface converts servo ticks to radians. Without a calibration file it falls back to a generic (ticks − 2048)·2π/4096 mapping, which produces the wrong joint range (most visible on the gripper — RViz shows it half-open at full physical open). Calibrate before first use:

1. Run the calibration tool and follow the prompts to record min / center / max ticks for each joint:

   ros2 run so_arm_100_hardware calibrate_arm.py
   

This writes so_arm_100_hardware/config/calibration.yaml.

1. Make sure the hardware plugin loads it. In so_arm_100_description/ros2_control/so_arm_100_5dof_position.ros2_control.xacro, inside the real-hardware <hardware> block, add:

   <param name="calibration_file">$(find so_arm_100_hardware)/config/calibration.yaml</param>
   

1. Rebuild and relaunch. If a joint’s range still doesn’t match the URDF after calibration, adjust the corresponding <limit> in so_arm_100_description/urdf/so_arm_100_5dof_arm.urdf.xacro (and the matching entry in so_arm_100_moveit_config/config/hardware_controllers.yaml) to match the value reported on /joint_states at the physical end-stop.

Installation

Create a ROS2 workspace (if you don’t have one)

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

Clone the repository

git clone git@github.com:brukg/SO-100-arm.git

Install dependencies

cd ~/ros2_ws
rosdep install --from-paths src --ignore-src -r -y

Build the package

```bash colcon build –packages-select so_arm_100

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