About
TL;DR: OpenBotBrain is a project to develop hardware and software to control Mindstorm™️ Lego® motors and sensors. It is developed on GitHub as open hardware and open source software.
What is it?
The Open Brain Bot (OBB) project is an effort to implement a robot controller that is compatible with Lego Mindstorm motors and sensors. OBB aims to design and publish completely open hardware and open firmware to support the use of OBB in educational and research settings.
Why are we doing this?
The motivation started from the need to replace Lego Mindstorm EV3s after the product was discontinued. Currently, we use them for a module that makes first year university students practice their programming skills. This serves as an introduction to robotics and, most importantly, as an excuse for programming in “realistic” environments that are messy and challenging to control. The idea is that building and programming dependable robots is conceptually related making robust programs in difficult environments.
When thinking about replacing the Mindstorm controllers, we want to preserve two important features:
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the students get to build an design their robots. The idea is that even if starting from a known design, it is important to have the ability to change it to make it easier to program, or more dependable. In a very real sense, the task is only to write a dependable robot, the design must follow that objective.
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the replacement should support a variety of programming environments. After all, the primary use is to make students practice programming during their second term in school. So the objective is not having the shortest time to robot or the cheapest most efficient robot. The main objective is to practice programming in a robotic environment. For example, the mindstorms are programmed in Java using the LeJOS because Java is what the students learned in the first term. But flexibility on this is also welcome because the board can be used for practicing other languages (we want to support MicroPython first class also).
It is not obvious from these requirements that the only (or even the best) solution is to design and build our own platform. In fact, if this were the only use, it would not make sense to develop this. The idea of the OBB is to build a community with many projects around it. The current status is that the board design for the first version is done, and students are working over the summer to develop firmware for this system. In a very concrete sense project is already delivering learning opportunities for students. Not yet about robotics but about embedded programming. Also the OBB is serving as a research platform for a project applying behavioural types to the challenge of supporting more than one way to program the future robots (there will be more projects soon).
So in a nutshell, the reason for this project is to have a versatile and open platform to develop educational and research projects.
How are we doing this?
The OBB is a board that uses microcontroller1 to interface 4 ports with motor controllers together with 4 ports to connect Mindstorm motors and sensors. Additionally, the board has a Raspberry Pi style 40-pin connector to communicate with a Raspberry Pi Zero 2 W (or similar). While the Raspberry Pi is not a hard requirement (e.g.: the OBB could run a robot implemented in MicroPython directly on the microcontroller, the platform becomes much more powerful and versatile when the Raspberry Pi Zero 2 W is connected. Concretely, a Raspberry Pi is required to support the LeJOS (or a LeJOS-like) environment, which is one of the motivating requirements for the project. However, as mentioned before the project is designed with versatility in mind in order to be suitable for different projects.
STM32L496ZG that was chosen because it has enough peripherals (GPIO, PWM, Timers, etc) to support all the Mindstorm devices and it was available when we designed the board during the post-pandemic semiconductor shortage.