LSS-P ROS2 Hardware Interface Package

The LSS-P-ROS2-Hardware repository contains the hardware interface for the Lynxmotion Smart Servos PRO (LSS-P) used to control the physical motors, as well as an example package to move a "RRBot" (2-joint robot).

Table of Contents

• Prerequisites
• Package installation
• Description package
• Author
• Resources

Prerequisites

1. Ubuntu 22.04 (Jammy Jellyfish)
2. ROS2 Humble
3. ROS2 dev tools:

sudo apt install python3-pip
sudo pip install colcon-common-extensions
sudo pip install vcstool

4. Rosdep: Used to install dependencies when building from sources

sudo apt install python3-rosdep2
rosdep update

Package installation

sudo apt install git
git clone https://github.com/Lynxmotion/LSS-P-ROS2-Hardware.git
mkdir -p src
mv LSS-P-ROS2-Hardware/* src
mv src LSS-P-ROS2-Hardware

Install dependencies

cd LSS-P-ROS2-Hardware
rosdep install --from-path src -yi --rosdistro humble

Build instructions

export GZ_VERSION=fortress
source /opt/ros/humble/setup.bash
colcon build --symlink-install

Initialization instructions

You will have to source the workspace in every new session in which you wish to use these packages:

source install/setup.bash

Description package

The description package contains the URDF description of the RRBot, or ''Revolute-Revolute Manipulator Robot'', which is a simple 3-linkage, 2-joint arm that we will use to demonstrate motor control.

View Model in Rviz

ros2 launch rrbot_example view_robot.launch.py

RRBot example package (ros2_control)

This package contains the controller setup to move 2 PRO motors using a simple position controlled robot with one hardware interface.

Before controlling the real robot first follow these steps:

1. Update the firmware on the servos using PRO Config

2. Follow the initial setup and make sure the IDs are configured correctly.

To control the servos:

1. Run the launch file

ros2 launch rrbot_example rrbot.launch.py

• Note: If the servos light up Blue they have been configured correctly if not try running:

sudo chmod 666 /dev/ttyACM0

2. You can test the forward position controller by opening another command interface and running the example:

source install/setup.bash

ros2 launch rrbot_example test_forward_position_controller.launch.py

3. To send a direct command use:

ros2 topic pub /forward_position_controller/commands std_msgs/msg/Float64MultiArray "data:
  - 3.1
  - -3.1"

• Note: The units are in radians, the hardware interface converts it to 0.01° degrees which is the unit used on the LSS-PRO communication protocol.

Author

• Geraldine Barreto

Resources

If you want more details about the LSS-P communication protocol, visit this website.

Official Lynxmotion PRO Robotic Arm ROS2 Package available here.

Read more about the PRO Robotic Arm in the Wiki.

Purchase the PRO arm on RobotShop.

Have any questions? Ask them on the RobotShop Community.