Robodog Goes Free Thanks To Unofficial SDK

What’s better than a pretty nice legged robot? One with an alternate SDK version that opens up expensive features, of course. The author didn’t like that the original SDK only came as pre-compiled binaries restricted to the most expensive models, so rolled up their sleeves and started writing a new one.

The manufacturer’s SDK limits access to programmatic functions, but that needn’t stop you.

There are a number of commercially-available robotic quadrupeds that can trace their heritage back to the MIT Mini Cheetah design, and one of them is the Unitree Go1 series which sports a distinctive X-shaped sensor cluster on its “face”. The basic models are affordable (as far as robots go, anyway) but Unitree claims only the high-priced EDU model can be controlled via the SDK. Happily, the Free Dog SDK provides a way to do exactly that.

The SDK is a work in progress, but fully usable and allows the user to send various high level and low level commands to the Go1 robots. High level examples include things like telling the robot to perform pushups, turn 90 degrees, or walk. Low level commands are things like specifying exact positions or torque levels for individual limbs. With the new SDK, doing those things programmatically is only a Python script away.

Know any other robots that might be based on the same system? This SDK might work on them, too.

Mini Cheetah Clone Teardown, By None Other Than Original Designer

[Ben Katz] designed the original MIT Mini Cheetah robot, which easily captured attention and imagination with its decidedly un-robotic movements and backflips. Not long after [Ben]’s masters thesis went online, clones of the actuators started to show up at overseas sellers, and a few months after that, clones of the whole robot. [Ben] recently had the opportunity to disassemble just such a clone by Dogotix and see what was inside.

Mini sheep, meet mini cheetah.

Amusingly, one of the first things he noticed is that the “feet” are still just off-the-shelf squash balls, same as his original mini cheetah design. As for the rest of the leg, inside is a belt that goes past some tensioners, connecting the knee joint to an actuator in the shoulder.

As one may expect, these parts are subject to a fair bit of stress, so they have to be sturdy. This design allows for slender yet strong legs without putting an actuator in the knee joint, and you may recall we’ve seen a similar robot gain the ability to stand with the addition of a rigid brace.

It’s interesting to read [Ben]’s thoughts as he disassembles and photographs the unit, and you’ll have to read his post to catch them all. But in the meantime, why not take a moment to see how a neighbor’s curious sheep react to the robot in the video embedded below? The robot botches a backflip due to a low battery, but the sheep seem suitably impressed anyway.

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Simple Mod Lets Quadruped Robot Stand And Walk

When it comes to locomotion, robots don’t typically do more than one thing at a time. Walkers stick to walking, and rollers stick to rolling. However, this simple method of enabling a cheetah-style quadruped to stand and even walk a little is pretty clever.

With just a couple of rigid struts attached to the shins of the rear legs, it becomes possible for the robot to lever itself up into a stable standing position, and even shuffle around a bit. Not bad for a couple bolted-on bits with no moving parts!

The robot style will look pretty familiar to some of our readers. It does resemble Boston Dynamics’ Spot but it’s closer to the MIT Mini Cheetah, whose design and brushless motors made for eye-catching agility and speed. It has inspired not just countless DIY efforts, but also kits of parts from overseas sellers.

The image here should make it clear how it works, but take a moment to also watch the short video embedded just below the page break, and see the process in action from beginning to end.

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MIT Mini Cheetah Made And Improved In China

We nearly passed over this tip from [xoxu] which was just a few links to some AliExpress pages. However, when we dug a bit into the pages we found something pretty surprising. Somewhere out there in the wild we…east of China there’s a company not only reverse engineering the Mini Cheetah, but improving it too.

We cover a lot of Mini Cheetah projects; it’s a small robot that can do a back-flip after all. When compared to the servo quadruped of not so many years ago it’s definitely exciting magic. Many of the projects go into detail about the control boards and motor modifications required to build a Mini Cheetah of your own. So we were especially interested to discover that this AliExpress seller has gone through the trouble of not just reverse engineering the design, but also improving on it. Claiming their motors are thinner and more dust resistant than what they’ve seen from MIT.

To be honest, we’re not sure what we’re looking at. It’s kind of cool that we live in a world where a video of a research project and some papers can turn into a $12k robot you can buy right now. Let us know what you think after the break.

Amazing Open Source Quadruped Capable Of Dynamic Motion

The more we read about [Josh Pieper]’s quadruped, the mjbots quad A0, the more blown away we are by his year of progress on the design. Each part of the robot deserves its own article: from the heavily modified brushless motors (with custom planetary gears) to the custom motor driver designed just for this project.

[Josh], realized early on that the off-the-shelf components like an ODrive just weren’t going to cut it for his application. So he designed his own board, took it through four revisions, and even did thermal and cycle testing on it. He ended up with the compact moteus board. It can pump out 400 Watts of peak power while its 3Mbit control protocol leaves plenty of bandwidth for real time dynamic control.

The motors and gearboxes are also impressive. It took thorough experimenting and taking inspiration from other projects  before he arrived at a 8108 quad copter motor modified and upgraded so heavily its own mother wouldn’t recognize it. This is all packed into a leg unit with three degrees of freedom that puts even the fanciest servo based quadruped to shame.

Finally it’s all packed into a neat four-legged robot frame with batteries and a Pi. You can get a video summary of the robot here or after the break, and we recommend reading his blog for some more images and details.

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Hackaday Podcast 037: Two Flavors Of Robot Dog, Hacks That Start As Fitness Trackers, Clocks That Wound Themselves, And Helicopter Chainsaws

Hackaday Editors Mike Szczys and Elliot Williams take a look at the latest hacks from the past week. We keep seeing awesome stuff and find ourselves wanting to buy cheap welders, thermal camera sensors, and CNC parts. There was a meeting of the dog-shaped robots at ICRA and at least one of them has super-fluid movements. We dish on 3D printed meat, locking up the smartphones, asynchronous C routines, and synchronized clocks.

Take a look at the links below if you want to follow along, and as always tell us what you think about this episode in the comments!

Take a look at the links below if you want to follow along, and as always, tell us what you think about this episode in the comments!

Direct download (60 MB or so.)

Continue reading “Hackaday Podcast 037: Two Flavors Of Robot Dog, Hacks That Start As Fitness Trackers, Clocks That Wound Themselves, And Helicopter Chainsaws”

Watch Legged Robot Run Circles Around Its Bigger Brethren

[Ben Katz] posted about bringing the Mini Cheetah (center, above) robot to the 2019 International Conference on Robotics and Automation (ICRA) held in Montréal, where it shared the floor with others for a workshop focusing on real-world deployment of legged robots. Those of you who haven’t been keeping up with legged robots may find yourselves delightfully surprised at the agility and fluid movements of this robot. Mini Cheetah may lack the effectors or sensors of the bigger units, but its nimbleness is undeniable.

[Ben] shared some footage of the robots together, and at about 7:22 in this video Mini Cheetah can be seen showing off a bit of flexing, followed by running around a larger unit. Another, shorter video is embedded below where you can see all the attendees moving about in a rare opportunity see them all together. You can even see the tiny one-legged hopping robot Salto if you watch closely!

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