Stack-chan's Journey: How It Became a Beloved Robot and Created a Subculture

Born on July 2, 2021, the adorable Stack-chan has just celebrated its second birthday!

What is Stack-chan?

The name Stack-chan (スタックチャン) may sound strange, and what is its relationship with M5Stack?

Actually, Stack-chan is an open-source robot project created by a user of M5Stack named Shinya Ishikawa. The name "Stack-chan" comes from the fact that it is built using M5Stack hardware, which is a modular system that allows users to stack different modules together to create custom electronic devices.

"Chan" is the Romanized pronunciation of the Japanese honorific suffix "ちゃん", which is a suffix in Japanese that is often used as a term of endearment or to show familiarity, similar to "dear" or "sweetie" in English.

So, "Stack-chan" is a cute and friendly name that reflects the robot's playful and approachable nature. Due to its cute and interesting appearance, it has gained a lot of popularity among users and even formed a unique subculture.

The exclusive Twitter account for Stack-chan:

"It's just so cute, you can't stop loving it."

At first, Shinya Ishikawa simply wanted to create a 100% open-source robot, but he never expected that this little robot would be loved by so many people, and even have the potential for mass production in the future.


Shinya noticed that most of the communication robots on the market are "closed", dependent on specific proprietary services, or their specifications are not disclosed to the public, and reaching the end of life as their backend services go by.


"Why don't they make communication robots more open and hackable?" It is the problem and why Stackchan was born. As a solution, He decided to create an open-source robot that anyone could build from scratch. This means that open community, rather than a closed, specific company or individual, will collaborate to grow the robot.


Based on this idea, in 2021, the prototype of Stack-chan was created. The robot consists of a case, an M5Stack’s controller Basic, which is a modular, stackable, and portable device with an ESP32-based microcontroller,  a dedicated expansion board, and firmware. Each component is fully customizable. The functionality as a communication robot is provided in the form of a framework, which users can easily access through applications (mods). M5Basic is equipped with wireless communication functions such as Wi-Fi and BLE, so it can be used with external services, smartphones, and other robots.


The most important feature of Stack-chan is that everything is open.

Stack-chan is open in two aspects.

First, All the resources of Stack-chan are distributed under Apache-2.0 license, including the schematics, the 3D model of the case and the firmware.

Second, Shinya opened up not only the source code and model data for Stack-chan but also the entire process of creating it. In other words, he shared widely the background issues, the decisions I made, the troubles he had, and the mistakes he made so that users can learn how to make and customize Stack-chan. People can follow the process by searching its official Twitter hashtags #stackchan, #スタックチャン on Twitter.

As a result, more than 30 enthusiasts soon began making Stack-chan, with applications ranging from voice assistants to quadruped robots, making Stack-chan's applications diverse and interesting. To date, over 500 users have joined Stack-chan's Discord group.


AI Stack-chan

As more and more users joined, Stack-chan's form and use became more diverse. Earlier this year, Chat-GPT became popular, and many users started trying to connect M5Stack devices to OpenAI's API. User @robo8080 combined Stack-chan and Chat-GPT to create an AI version of Stack-chan. The intelligence level of the AI version of Stack-chan was significantly improved, and it quickly gained a lot of attention and popularity.

Stack-chan themselves has no special mission to solve. They just live. They have multiple communication modalities such as speech and gaze. In despite of its small size, Stack-chan has a very lifelike appearance with its eyes and breathing.


This behavior is achieved by simulating neurophysiological phenomena such as saccadic eye movements.

But who cares about the detail? However, what truly matters is that everyone treats Stack-chan as a real child and loves it dearly. In fact, some users have even started discussing what style of commemorative shirts to create for Stack-chan.


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