stretch_tutorials/ros2/remote_compute.md

Using a Remote Workstation to Offload Heavy Compute

In this tutorial, we will explore the method for offloading computationally intensive processes, such as running computer vision models, to a remote workstation computer. This approach offers several advantages such as:

• Save processing power of the Robot.
• Utilizing the available GPU hardware on powerful workstations to run large deep learning models.
• Ability to strategically offload less critical high-computation process to enhance Robot's efficiency.

In this tutorial, we will delve into the intricate process of offloading Stretch Deep Perception ROS2 nodes. These nodes are known for their demanding computational requirements and are frequently used in Stretch Demos.

NOTE: All Stretch ROS2 packages are developed with Humble distro.

Setting a ROS_DOMAIN_ID

ROS2 utilizes DDS as the default middleware for communication. DDS enables nodes within the same physical network to seamlessly discover one another and establish communication, provided they share the same ROS_DOMAIN_ID. This powerful mechanism ensures secure message passing between remote nodes as intended.

By default, all ROS 2 nodes are configured with domain ID 0. To avoid conflicts, select a domain ID from the range of 0 to 101, and then set this chosen domain ID as the value for the ROS_DOMAIN_ID environment variable in both the Workstation and the Robot.

export ROS_DOMAIN_ID=<ID>

Setup the Workstation to work with Stretch

The workstation needs to be installed with the appropriate stretch related ros2 packages to have access Stretch robot meshes for accurate Visualization in Rviz,interfaces dependencies and essential perception packages.

This section assumes the workstation already has an active ROS2 distro and colcon dependencies pre-installed. You can find ROS2 Installation step for Ubuntu here.

Setup Essential stretch_ros2 Packages

Make sure the ROS2 distro is sourced.

source /opt/ros/humble/setup.bash

Create workspace directory and clone stretch_ros2 packages along with it's dependency packages to src folder.

mkdir -p ~/ament_ws/src
cd ~/ament_ws/src/
git clone https://github.com/hello-robot/stretch_ros2
git clone https://github.com/hello-binit/ros2_numpy -b humble
git clone https://github.com/IntelRealSense/realsense-ros.git -b ros2-development
git clone https://github.com/Slamtec/sllidar_ros2.git -b main
git clone https://github.com/hello-binit/respeaker_ros2.git -b humble
git clone https://github.com/hello-binit/audio_common.git -b humble

Build and install all the packages present in source folder.

cd ~/ament_ws
rosdep install --rosdistro=humble -iyr --skip-keys="librealsense2" --from-paths src
colcon build --cmake-args -DCMAKE_BUILD_TYPE=Release

Make sure to source the workspace to discover the packages in it.

source ~/ament_ws/install/setup.bash

Setup Robot URDF and Meshes

All the robots are shipped with an calibrated URDF files configured with robot version specific meshes that would more accurately match the actual robot you are using. So we recommend you to copy the stretch_description directory that exists in your robot and replace it with the one existing in the workstation. The Stretch Description directory exists in the path ~/ament_ws/src/stretch_ros2/stretch_description.

If you dont want use the URDFs from the robot, you can manually generate the right URDF w.r.t your robot configuration using the following commands:

cd ~/ament_ws/src/stretch_ros2/stretch_description/urdf/

#if Dex-Wrist Installed
cp stretch_description_dex.xacro stretch_description.xacro

#if Standard Gripper
cp stretch_description_standard.xacro stretch_description.xacro

ros2 run stretch_calibration update_uncalibrated_urdf
cp stretch_uncalibrated.urdf stretch.urdf

After setting up the

cd ~/ament_ws
colcon build

Download Stretch Deep Perception Models

cd ~/ 
git clone https://github.com/hello-robot/stretch_deep_perception_models

TODO: Parameterize models_directory

Robot Side Nodes

Start Stretch Driver Node

Starts bla bla

ros2 launch stretch_core stretch_driver.launch.py

Start Realsense Camera Stream Node

Starts bla bla

ros2 launch stretch_core d435i_high_resolution.launch.py

Start RP Lidar Node

Starts bla bla

ros2 launch stretch_core rplidar.launch.py

Workstation Side Node

Start 'Detect Nearest Mouth' Computer Vision Node

Starts Bla Bla

ros2 launch stretch_deep_perception stretch_detect_nearest_mouth.launch.py

Start Funmap Planner

Starts Bla Bla

ros2 launch stretch_funmap funmap.launch.py

Visualization from Rviz