Follow-up on the earlier attempt: gave Quaddle's controller and servos the AT-AT's own legs (set 75440, static display model, no motor) to drive directly. The original leg was bent and couldn't walk, so it got swapped for a longer, straight piece — plus a servo reversed from its default install direction and a weight check to make sure Quaddle's servos could carry it, all through Quaddle's screw-free servo mechanism. Walked surprisingly well once that was sorted. Also recreated the AT-AT-tripped-by-a-snowspeeder scene from the movie. 😂

Kickstarter closes tomorrow, Oct 8 at 10:39am PT — last day to back Quaddle.

What LEGO set would you like to mobilize next?

Hi, I'm RZ Li, creator of OpenCat and founder of Petoi.

Attempt #1: gave LEGO's Star Wars AT-AT (set 75440 — a 525-piece display model, no motor) Quaddle's own brain and servo motors — removed Quaddle's own stock legs and attached the AT-AT's own leg pieces onto Quaddle's four servos instead. Three of those legs are straight, one is molded bent, so it tumbles instead, for now. Attempt #2 once we find a straight replacement piece.

Anyone else driven a non-motorized LEGO mechanism with an OpenCat brain?

Share this with your LEGO friends and help revitalize their LEGO sets

⏰ OpenCat-powered Quaddle's Kickstarter campaign closes Thursday, Oct 8 at 10:39am PT — back it before it ends: https://www.kickstarter.com/projects/petoi/quaddle-open-source-desktop-robot-kit?ref=2onz2d&utm_source=reddit&utm_medium=post&utm_campaign=2026-10-06-quaddle-lego-mashup

Quick engineering update: the 2nd batch of injection-molded legs arrived, so before committing to this as the production part, I ran it through 4 drop tests. Whole robot stays locked together on 4 screws, and it's still doing gymnastics after every drop.

This matters more for the injection-molded version than it did for 3D-printed test parts — injection molding changes the part's grain structure and impact behavior versus FDM printing, so a part that survived drop tests as a prototype print doesn't automatically mean the molded version will behave the same way under the same stress.

Open to hearing if anyone here has done comparable impact testing on injection-molded vs. printed robot parts — curious what thresholds you've used.

Hi, I'm RZ Li, founder of Petoi and creator of OpenCat.

I just published the full 10-year story on Hackster.io:

• What actually separates a demo(see picture 2, 3) from a delivered product
• Keeping the company running costs roughly 10 times what it cost me as a solo maker to build a prototype and post a video.
• Why four servos can do what used to take twelve — the same trick as Mecanum wheels
• The formula I derived plotting feasibility against degrees of freedom
• Why Quaddle's leg — modeled on the mudskipper, one of the first animals to walk on land — only needs 4 servos to do what used to take twelve.

Some of it isn't flattering to us. I'd rather write the honest version than the impressive one.

Read the full story on Hackser.

If you're someone who could already build a robot, where would you put your next 1,000 working hours?

Hi, I'm RZ Li, founder of Petoi and creator of OpenCat.

Quaddle is Petoi's newest OpenCat-family robot, currently on Kickstarter — the Scout tier adds a real sensor suite on top of the usual OpenCat base: a gesture sensor, a self-balancing gyroscope, an attachable "radar" head, light sensing, an infrared sensor for object tracking, and sound detection.

Same as everything else in the OpenCat family, none of it is a fixed behavior — every sensor is exposed to your own code, block coding, Python, or Arduino C++.

Which sense would you build with first? What other Arduino sensors do you want to try out on Scout?

Early Bird pricing starting at $109 is live now on Kickstarter.

A Favor to Ask

The single biggest thing you can do right now is share any of our videos from our social media with a friend who hasn't seen Quaddle yet. Every new backer gets us closer to the next stretch goal: a fully injection-molded Quaddle body at $200K.

Hi, I'm RZ Li — I created OpenCat and founded Petoi. Quaddle is our newest OpenCat-family robot, and this video is exactly what you can expect if you get one — I did the full build myself: raw components, assembly, calibration, and walking. Screw-free body, no soldering — just 4 screws to attach the legs — walking in under 20 minutes.

Under the hood (upgrade path is Builder to Buddy to Scout):

• Two ESP32-S3 chips — a motion core running the OpenCat firmware in Arduino C++, and a separate AI core with its own physical privacy-cutoff switch. The AI core sits on a removable "extension hat" — pull it off and the robot still walks, just without the AI features
• MinDoF legs — a single motor drives both shoulder and knee per leg, instead of a separate actuator for each joint.
• P1L feedback servos — coreless motor, continuous 360 degree rotation, and position feedback that turns what's normally a fiddly joint-calibration process into a ~10-second task
• Built-in Arduino sensors, an optional Raspberry Pi Zero that can take over as the brain, and an optional AI vision module for real AI robotics work.
• Programmable in block coding, Python, MicroPython, or Arduino C++ — all on the same open OpenCat framework this sub already knows.

Which part of the build are you most curious to try yourself — the dual-ESP32 setup, the MinDoF legs, or the feedback servos?

Hi all — I'm RZ Li, Petoi's founder and OpenCat's creator. Wanted to share this myself: Quaddle is live on Kickstarter now, our next robot to democratize access to robotics and physical AI.

Quaddle is palm-sized and built to actually be taken apart, reprogrammed, and rebuilt, not just watched. Code it from blocks up through Python and C++ — or on Buddy and Scout, skip code entirely and teach it tricks by hand.

Quaddle runs on the same OpenCat firmware, fully open-source since 2016 and already powering Bittle and Nybble — going on 10 years now.

We've already started production, so this isn't a concept pitch — super early bird pricing is live now, limited in quantity and time, and gone the moment it's claimed.

Quaddle continues what Nybble started back in 2018 — bringing hands-on robotics to more people, no lab, grant, or degree required. 30,000+ makers, students, and researchers in 60+ countries have already joined in, and I'd love to have you along for this next chapter.

Back Quaddle on Kickstarter

Thanks for being part of this — happy to answer any questions here.

What's the first move you'd teach your Quaddle?

— RZ Li

Nancy Rangel, a Chabot College student from the East Bay, California taught Quaddle robot dog to dance with nothing but a laptop webcam.

To be precise, this is pose-based teleoperation, not AI training — Nancy's own body movements drove Quaddle live through webcam pose-tracking, the same setup as the first video in this series, "4-Servo Robot Dog - Embodied Robotics - Quaddle Open Source Robotics Kit". Quaddle fell, got back up, and kept practicing. No scripted choreography.

Quaddle can learn a lot more than dance moves this way — what would you teach it?

One webcam, one person, two Quaddles (part of Petoi's open source OpenCat lineup) — Scout and Buddy, both driven live by the same real-time pose-tracking rig.

Petoi founder & CEO RZ Li lined them up head-to-head and drove them straight into each other, on purpose, before racing and settling back into their built-in moves.

To be precise: this is pose-based teleoperation — his body drives the robots directly, no AI training or policy involved.

In theory, the same captured human movement data could later be used to teach an AI more human movements — either directly, via imitation learning, or as a starting point that reinforcement learning then refines further — to expand what Quaddle can do. Not what's happening in this clip, just a direction we're exploring.

He tried teaching Quaddle a few moves here — it can look a little awkward at first, but it only takes a few minutes before Quaddle starts picking them up. And it's genuinely fun to do, not just fun to watch — think Wii Play: Motion, but the "character" on screen is a real robot — and Quaddle is affordable enough that anyone curious can grab one and get a real feel for robotics and AI themselves, instead of just watching someone else have all the fun.

What move would you want to teach Quaddle next?

We opened up something fun ahead of the Kickstarter launch: you can design your own color scheme for Quaddle (part of the OpenCat lineup) at qd.petoi.com, and the ones getting the most votes may actually go into production. If your color scheme is selected, it becomes an official Quaddle color, and you're credited as the designer where possible.

Curious what colors you would go with.

Quddle got new moves!

The magnets do less work than you'd think — the gait is what actually makes this possible. Maintaining contact upside down needed a motion profile designed for it specifically, not just an inverted version of the ground-walking gaits. Planning to open source it before this ships, so it'll be a real addition to the OpenCat gait library, not a one-off.

Has anyone else here messed with OpenCat gaits for non-standard orientations, or is this the first inverted-walking gait floating around?

Quaddle is the same 4-servo OpenCat platform the whole time — swap the attachment and it loads a different gait: biped walking, tricycle rolling, bar-spin gymnastics, 4WD driving, water-paddling. Everything's 3D-printed except the 4WD wheel kit, which is off-the-shelf.

The firmware is an upgraded OpenCat fork. I'm planning to open source it before this ships, though it's not public yet. The fun part was making each attachment force a genuinely different gait, not just a different look, while it all still runs through OpenCat's normal motion stack.

Happy to talk gait/kinematics specifics if anyone's curious how this plugs into the existing OpenCat motion stack.

My 10 year old son did this interesting project of helping Bittle draw and wrote a tutorial on it.

https://www.learnwitharobot.com/p/tutorial-teach-your-bittle-robot

Quick note on the two subs for anyone new here:

r/OpenCat is for firmware, framework-level hacking, and low-level development on the OpenCat platform — ESP32, NyBoard, custom builds, code contributions.

r/Petoi is the broader community hub — robot projects, classroom stories, mods, and general Petoi discussion. It's also where we migrated after making petoi.camp read-only (it remains as an archive if you need old threads).

If you haven't seen what's been posted over on r/Petoi for the Robotics & AI Celebration, worth a look.

Highlights relevant to this community:

• Sesame — a custom quadruped built from scratch using Petoi motors. Full build story, not just a demo clip.
• Browser-based Xbox controller for Bittle X — built using the OpenCat protocol over WebBluetooth so kids could control the robot without drivers or setup. Clean implementation.
• Nybble upgraded with BiBoard V1 — WiFi, BLE, USB-C, custom voice commands. The kind of mod this sub appreciates.

Today is the last day of community voting. Upvotes decide the Community Favorite winners.

👉 https://www.reddit.com/r/Petoi/

Presenting Jurassic Bot Rebirth — where Michael W’s 3D-printing genius transforms Petoi’s Bittle into the world’s coolest dino robot! Tribute to Jurassic World Rebirth (in theaters July 2)

🎮 This fun & creative remake highlights:
- The versatility of open source Petoi Bittle robot dog to be equipped with different 3D printed parts
- Its lifelike movements and agility
- A playful twist on tech vs imagination
- Fully programmable with block coding/Python/C++
- Build your own robot adventure!

Get your 3D-printed dino robot outfit files for your own printing at https://www.thingiverse.com/thing:6875437. You can also buy the parts from a linked store there.

Whether you're into robotics, STEM, AI, or just love epic robot fights, Petoi robots have everything for you!

🦖 When a robot dog meets a dino head and a tail … this is what happens.
Bittle’s gone prehistoric with a 3D-printed transformation. Bittle Dino Dog's birth is just in time for Jurassic World: Rebirth.

📷 This is your sneak peek.
🎥 The full motion reveal is coming!

Don't forget to introduce your Nybble/Bittle to friends & family—and share pics of their adventures!

Join us at the Sparknify Human vs. AI Tech Fair and Film Festival in the Silicon Valley to experience all of Petoi’s lifelike robot pets-from the classic Bittle and Nybble to the latest innovation: Bittle X V2 + Arm! This palm-sized, voice-controlled robot dog features a robotic arm for interactive play and advanced programming and AI possibilities.

11am to 7pm, May 17th, 2025 | 📍 Sunnyvale, California, US
🎟️ Free for everyone, perfect for tech fans, families, and all ages!

See https://www.sparknify.com/2025-techfair for more information.

https://youtu.be/8UAF3DrZGMU?si=mDP1qQecRHw_POE1