Kaia.ai ROS2 telemetry package

Kaia.ai ROS2 kaia_telemetry package communicates with the Kaia.ai ESP32-based robot, receives raw sensor telemetry data over WiFi using Micro-ROS and re-publishes the telemetry to standard ROS2 topics:

• robot laser scan data on the /scan topic
• robot wheels and servos position on the /joint_states topic
• robot wheel odometry on the /odom topic
• robot odometry transform on the /tf topic

The telemetry message is a ROS2 custom message designed to be as compact as possible in terms of its size in order to reduce communication latency and minimize dropped packets, thus keeping the robot's navigation responsive and agile.

The kaiaai-ros and kaiaai-ros-dev Docker images already include a pre-compiled kaiaai_telemetry package. In case you'd like to modify and/or build this package for development purposes, please follow these steps:

• on your PC run this command (e.g. in a Windows shell) to launch the Kaia.ai development Docker image. The image should launch and give you a bash prompt.

docker run --name kaiaai-ros-dev-iron -it --rm -p 8888:8888/udp -e DISPLAY=host.docker.internal:0.0 -e LIBGL_ALWAYS_INDIRECT=0 kaiaai-ros-dev:iron

• navigate to the development workspace, manually build, install and launch Kaia.ai packages including kaiaai_telemetry

cd /ros_ws
colcon build
. install/setup.bash
ros2 launch kaiaai_bringup main.launch.py robot_model:=makerspet_loki

• open one more bash prompt by running this command (e.g. in a Windows shell)

docker exec -it kaiaai-ros-dev-iron

• at the newly opened bash prompt, run the telemetry node that subscribes to the raw telemetry data on /telemetry topic, converts the raw telemetry data to proper ROS2 messages re-publishes those on /scan, /joint_states, /odom and /tf topics.

ros2 run kaiaai_telemetry telem

• open yet another bash prompt and inspect the raw telemetry data going "in" on the /telemetry topic and the converted telemetry data published on the /scan, /joint_states, /odom and /tf topics, etc.:

ros2 topic list
ros2 topic echo /telemetry
ros2 topic echo /scan
ros2 topic echo /odom
ros2 topic echo /joint_states
ros2 topic echo /tf

If you need to recreate the ROS2 workspace and re-populate the package source code, run commands from this file before proceeding with the build, install and launch (see above):

If you don't have a robot handy, you can also run the test node that publishes some fake telemetry data directly to /telemetry, bypassing Micro-ROS

ros2 run kaiaai_telemetry test_pub

Once you are ready to test and deploy your modifications into the end user Docker image, follow and modify the instructions on rebuilding the end user Docker image to your liking to build an end user Docker image for your own robot design.

Modding the default robot

The telemetry launch commands described above default to makerspet_snoopy robot, which defined in the makerspet_snoopy robot description package. To create a new robot named jack45_waldo, start by cloning an existing robot description package makerspet_snoopy into jack45_waldo and proceed with modding jack45_waldo files. The file containing telemetry parameters for jack45_waldo is /ros_ws/src/jack45_waldo/config/telem.yaml

cp -r /ros_ws/src/makerspet_loki /ros_ws/src/jack45_waldo

Modify files in /ros_ws/src/jack45_waldo/ as needed, including /ros_ws/src/jack45_waldo/config/telem.yaml

Now you can run telemetry on jack45_waldo with jack45_waldo-specific telemetry parameters as follows:

ros2 run kaiaai_telemetry telem robot_model:=jack45_waldo