About the project

OpenCat is the open-source Arduino and Raspberry Pi-based quadruped robotic pet framework developed by Petoi, the maker of Boston Dynamics-style futuristic programmable robot dogs, robot cats and robot pets for STEM education and AI-enhanced services.

Project info

Difficulty: Difficult

Platforms: ArduinoPythonOpenCat

Estimated time: 2 hours

License: MIT license (MIT)

Items used in this project

Software apps and online services

Petoi app Petoi app



OpenCat is the open-source Arduino and Raspberry Pi-based quadruped robotic pet framework developed by Petoi, the maker of futuristic programmable robotic pets.

Inspired by Boston Dynamics' Big Dog, Dr. Rongzhong Li started the project in his dorm in 2016. After one year of R&D, he founded Petoi LLC and devoted all his resources to the startup. The goal is to foster collaboration in quadruped(four-legged) robotic research, education, and engineering development of agile and affordable quadruped robot pets, bring STEM concepts to the mass and inspire newcomers (including many kids and adults) to join the robotic AI revolution to create more applications.

The project is still a complex system only for skilled makers, yet we want to share our design and work with the community by mass production and bring down the hardware and software costs. OpenCat has been deployed on Petoi's bionic palm-sized, realistic lifelike cute robot cat Nybble and high-performance robot dog Bittle. We now have established a production line and can ship these affordable robotic kits and accessories worldwide.

This project provides a base open-source platform to create amazing programmable gaits, locomotion, and deployment of inverse kinematics quadruped robots and bring simulations to the real world via C/C++/Python programming languages. Our users have deployed NVIDIA Issac simulations and reinforcement learning on our robots. Our users have also successfully deployed OpenCat on their DIY 3D-print robot pets.

We've successfully crowdfunded these two mini robot kits and shipped thousands of units worldwide. With our customized Arduino board and servos coordinating all instinctive and sophisticated movements(walking, running, jumping, backflipping), one can clip on various sensors to bring in perception and inject artificial intelligence capabilities by mounting a Raspberry Pi or other AI chips(such as Nvidia Jetson Nano) through wired/wireless connections. Please see Petoi FAQs for more info.

Also, Check out all of the OpenCat and Petoi robot user showcases.

OpenCat software works on both Nybble and Bittle, controlled by NyBoard based on ATmega328P. To run the code on our robot models, first change the model and board definition in OpenCat.h, then upload WriteInstinct.ino.

#include "InstinctBittle.h" //activate the correct header file according to your model
//#include "InstinctNybble.h"

//#define NyBoard_V0_1
//#define NyBoard_V0_2
#define NyBoard_V1_0

Set No line ending in the serial monitor and baudrate as 115200 (or 57600 for NyBoard V0_*). Enter three capitalized Y after the prompts and wait for the MPU to calibrate. Then upload OpenCat.ino as the main functional code.

More detailed documentation can be found at the Petoi Doc Center.

You can use our mobile app to remote-control the robots as well:

For updates:

  • star this repository to receive timely notifications on changes.
  • visit and subscribe to our official newsletters for project announcements. We also host a forum at
  • follow us on Twitter, Instagram, and YouTube channel for fun videos and community activities.

Advanced tutorials made by users

Review, open-box, and demos by users

The old repository for OpenCat is too redundant with large image logs and will be obsolete after adding compatibility notes in the documentation.


Photo of Petoi


Petoi is the maker of futuristic bionic robot pets for adults and kids. The robots are high-performance, remote/app controlled, and highly programmable. The robotics kits are built on top of Arduino and can be extended with popular open source hardwares such as Raspberry Pi and Arduino modules. Petoi is also the creator of OpenCat, a popular open-source quadruped(four legged) robot platform.


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