Kaia.ai makes use of Micro-ROS for Arduino. This article provides step-by-step instructions on how to (re)build the Micro-ROS Arduino library.

I don’t normally expect anyone to be rebuilding this library, so these instructions are, essentially, a documentation for myself.

In some cases, tayloring Kaia.ai software for your particular robot may require tweaking your robot’s Kaia.ai-compatible firmware. For example a firmware tweak may be necessary when adding new robot sensors.

The Micro-ROS library communicates sensor data from the Arduino micro-controller (ESP32 in our case) to the PC running ROS2, where the sensor data gets processed.

If the newly-added sensor outputs the type of data that the Micro-ROS library does not support already, the Micro-ROS library has to be extended accordingly. That includes tweaking the Micro-ROS code - e.g. adding a special message type for the new sensor’s data - followed by rebuilding the library.

As the first step in the process, follow these steps to extend Micro-ROS - for example by creating a new sensor message type.

Next, set up your PC for building the Micro-ROS Arduino library.

• Install Docker for your PC platform and make sure the Docker agent is running, see these instructions
• Install the Micro-ROS Arduino library for Kaia.ai using these instructions

Let’s assume you are using Arduino IDE for Windows and your Arduino libraries are stored under C:\Users\YOUR-USER-NAME\Documents\Arduino\libraries.

• Open a Windows command shell and run these commands to rebuild the library using the Micro-ROS library builder:

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  cd %HOMEPATH%\Documents\Arduino\libraries
  git clone -b iron --depth 1 https://github.com/kaiaai/micro_ros_arduino_kaiaai micro_ros_kaiaai
  

• if necessary, revise your library source code
• if necessary, add your new custom message repo to extras/library_generation/extra_packages/extra_packages.repos
• build the library

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  docker run -it --rm -v .\micro_ros_kaiaai:/project --env MICROROS_LIBRARY_FOLDER=extras microros/micro_ros_static_library_builder:iron
  

• manually copy src\micro_ros_kaiaai.h from the GitHub repo’s to Arduino\micro_ros_kaiaai\src\
• optionally, update library.properties
• optionally, commit and push the updated library back to GitHub

Please note, you can also rebuild the library for a particular platform only, e.g. for ESP32. By default, Micro-ROS Arduino library builds for stm32, OpenCR, Teensyduino, samd, sam, mbed, esp32 and mbed_portenta architectures.

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docker run -it --rm -v .\micro_ros_kaiaai:/project --env MICROROS_LIBRARY_FOLDER=extras microros/micro_ros_static_library_builder:iron -p esp32

Also, if needed, change iron in the instructions above to another ROS2 distro name, e.g. humble.