OpenCat — Open-Source Quadruped Robot Framework

On current-gen hardware (Bittle X, Nybble Q) or starting fresh? This repo covers the legacy NyBoard platform. Head to OpenCatESP32 for current hardware and active development.

🚀 Quaddle — Petoi's newest OpenCat-lineage quadruped — goes live on Kickstarter Sept 2, 2026. Get notified → (details below)

OpenCat is an open-source Arduino and Raspberry Pi-based framework for building and programming quadruped robots. Developed by Petoi, the maker of futuristic programmable robotic pets, it's the framework behind two mini robot kits: the Bittle robot dog and the Nybble robot cat.

The framework handles the hard parts — gait coordination, servo control, IMU integration — so you can focus on what you're actually building on top of it.

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Quaddle mini robot dog — launching on Kickstarter Sept 2, 2026

Quaddle is Petoi's newest quadruped, going live on Kickstarter Sept 2, 2026 — a mini desk robot built on the same OpenCat lineage as Bittle and Nybble.

• Full quadruped running on just 4 servos instead of the usual 8–12, which forces genuinely different gait-design and leg-coordination solutions to still get all four legs walking, running, and balancing
• Position-feedback servos — readable, not just drivable — which is what makes Puppet Mode possible: hand-guide the legs and record a motion directly, no code required
• 3D-printable shells and mounts for customization
• Same open platform this repo already supports for gait research, reinforcement learning (RL), and sim2real work — a hands-on physical AI platform, not a toy version of the idea
• Try it in the online simulator before it ships

Source code is not yet public. It's an upgraded version of the OpenCat project. The ESP32-S3 code structure is similar to this repo and closer to OpenCatESP32, which already powers thousands of Bittle X and Nybble Q robots in the field. We plan to open source it before Quaddle delivery.

• Watch this repo and r/petoi for the open-source announcement
• Get notified on Kickstarter when it goes live
• Check out the Quaddle Hugging Face page

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About the Project

Inspired by Boston Dynamics' Spot, Dr. Rongzhong Li started OpenCat in his dorm at Wake Forest University in 2016. The goal was straightforward: make agile quadruped robots affordable and hackable enough for researchers, educators, and makers — not just well-funded labs.

Since then:

• 30,000+ robots shipped, cumulative across all channels
• 60+ countries
• $1M+ raised across two prior Kickstarter and Indiegogo campaigns
• 20+ academic papers cite the platform — see Research Spotlight
• One of the most-starred open-source quadruped robot projects on GitHub

OpenCat is now deployed across two robot platforms and used in K-12 schools, university research labs, maker spaces, and independent projects worldwide.

Current Hardware

• 🐶 Bittle X — mini robot dog & AI robotics kit with voice control — current generation, BiBoard/ESP32
  • Also available on Amazon
  • Try the simulator
• 🐱 Nybble Q — mini robot cat & AI robotics kit — current generation

The original Bittle and Nybble mini robots (NyBoard/ATmega328P) are discontinued but still fully supported by this codebase. This repo is the right place for NyBoard users; for ESP32/BiBoard see OpenCatESP32.

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What the Framework Gives You

• Multi-language: C/C++, Python, block-based coding
• Open hardware + software: fork, modify, extend — no vendor lock-in
• Arduino + Raspberry Pi native: works with the tools you already use
• Sensor integration: cameras, touch, IMUs, ultrasonic, etc. — clip and go
• Sim-to-real: experiment reinforcement learning models on an affordable robot
• ROS compatible: SLAM, navigation, and perception pipelines documented by the community

Whether you're teaching robotics programming for the first time, building a weekend hackathon project, or running a graduate-level embodied robotics experiment, the platform scales.

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What the Community Has Built

Users have shipped real robotics projects across AI, Raspberry Pi, and research — a few highlights:

• Autonomous movement & object detection
• Raspberry Pi robotics projects
• AI and computer vision applications
• NVIDIA Isaac simulations and reinforcement learning
• Visual and LiDAR-based SLAM with ROS
• Imitation learning with Tiny ML models
• IoT robot fleet management with AWS
• 3D-printed accessories and custom builds
• DIY 3D-printed robot pets on OpenCat
• Research Spotlight — academic and research use cases

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Hardware

This repo targets the NyBoard — a customized Arduino board based on ATmega328P. It coordinates up to 12 high-performance servos for walking, running, jumping, and backflipping.

Extend with:

• Sensor pack
• Intelligent camera module
• Raspberry Pi, Nvidia Jetson Nano, or other AI co-processors via wired/wireless connections

For ESP32/BiBoard (current-gen hardware), see OpenCatESP32.

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Setup

Full documentation: Petoi Doc Center The following steps give you a brief walk-through, but may miss detailed tips and illustrative pictures.

1. Clone the repo

Remove the -main (or branch name) suffix from the folder after downloading.

2. Open OpenCat.ino — select your robot and board

#define BITTLE    // Petoi 9 DOF robot dog: 1x on head + 8x on leg
//#define NYBBLE  // Petoi 11 DOF robot cat: 2x on head + 1x on tail + 8x on leg

//#define NyBoard_V0_1
//#define NyBoard_V0_2
#define NyBoard_V1_0
//#define NyBoard_V1_1

3. Enter configuration mode

Comment out #define MAIN_SKETCH, upload, follow serial prompts.

// #define MAIN_SKETCH

4. (Optional) Auto-init

#define AUTO_INIT skips prompts and auto-calibrates IMU — handy for repeated flashing.

5. Upload

Plug USB uploader into NyBoard, install driver if needed, hit upload (→) in Arduino IDE.

6. Serial Monitor

Set to no line ending and 115200 baud rate.

7. Reset joint offsets

Reset joint offsets? (Y/n)
Y

8. IMU calibration

Calibrate the IMU? (Y/n):
Y

Place the robot flat on a table. 6 long beeps → reads sensor data → saves offsets → beeps when done. Close Serial Monitor when Ready! appears.

9. Switch to main sketch

#define MAIN_SKETCH

Uncomment and re-upload.

10. Joint calibration

Boot with one side up to enter calibration mode, or calibrate directly via Serial Monitor.

11. Optional: Petoi app

Plug in Bluetooth dongle for a friendlier calibration UI:

• iOS: App Store
• Android: Google Play

See the calibration guide and app guide.

12. Start building

Infrared remote, Petoi app, Python, or Serial Monitor. Full play guide →

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Education

OpenCat shows up in AI robotics education across K-12 programs, community colleges, university labs, and maker spaces — hands-on physical AI teaching that goes beyond screen-based coding exercises:

• Robotics education showcases
• STEM & robotics curriculum resources
• Robotics competitions

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Community & Discussion

• r/OpenCat — firmware code, framework hacking, extending and porting OpenCat
• r/Petoi — hardware Q&A, builds, quadruped coding, RL experiments, curriculum, 3D-printed parts, general discussion
• Facebook Group — community discussion and builds

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Resources

• Advanced tutorials by the community
• GitLab embedded DevOps workshop with Bittle X
• Talking Petoi robot dog with Azure AI Model Inference API integration
• Talk to Bittle robot dog with ChatGPT
• Research spotlight
• Robot gallery
• FAQ

Follow the project:

• YouTube
• Twitter
• Instagram
• Facebook
• LinkedIn
• TikTok

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The legacy OpenCat repository is archived and no longer maintained.