OpenCat

August 16, 2026 · View on GitHub

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, or buy Bittle X on Amazon.

🚀 Quaddle — Petoi's newest OpenCat-lineage quadruped — launches on Kickstarter August 2026. Reserve your spot → (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.

Coming Soon: Quaddle mini robot dog

Quaddle is Petoi's newest quadruped, launching on Kickstarter August 2026 — a mini desk robot built on the same OpenCat lineage as Bittle and Nybble. What makes it worth a look: it's a 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. Its servos are also position-feedback — readable, not just drivable — which is what makes Puppet Mode possible: hand-guide the legs and record a motion directly, no code required to capture a new behavior. We'll also share 3D-printable shells and mounts for customization. Same open platform this repo already supports for gait research, RL, and sim2real work — a hands-on physical AI platform, not a toy version of the idea.

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 announcement, or reserve a spot to get notified at launch.

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

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.

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.

What the Community Has Built

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

Academic and research use cases: Research Spotlight

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:

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

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:

See the calibration guide and app guide.

12. Start building

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

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:

Community & Discussion

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

Resources

Follow the project: YouTube · Twitter · Instagram · Facebook · LinkedIn

The legacy OpenCat repository is archived and no longer maintained.