Launch HN: Vassar Robotics (YC X25) – $219 robot arm that learns new skills
Edit: the entire run sold out thanks to HN today—thank you all! And sorry to anyone who missed out. You can get in on the next batch here: https://vassarrobotics.com/newsletter.
We are bringing an upgraded version of the long beloved SO-101 robot arms to a $219 price point with improved mechanical design and added intelligence. See what it can do here: https://youtube.com/shorts/xNyPKJZI400 (demos are sped up as shown in the video)
I’ve spent a few years building RC planes (https://cyo.ng/hangar/) and micro gas turbines (https://set.mit.edu), and I’ve always wished hardware were cheaper so more people could experiment.
I’m now launching a $219 desktop robot-arm kit that keeps LeRobot SO-101’s kinematics, swaps key parts for sturdier, more precise SLA prints, and adds two integrated 480 p cameras. After plenty of supplier haggling, the whole kit costs less than the twelve servos alone. I’ll release the updated mechanical design under an MIT license by June 30.
On the software side, I'll also release an MIT-licensed MCP server by June 30 that exposes the local robot policy as tools for agentic LLMs (Opus 4, o3, etc.) to use in long-horizon tasks. Here's how it works: You can teach the robot new skills through teleoperation. During inference, you simply talk to the agentic LLM using natural language instructions. The LLM then calls the local robot policy through MCP, automatically decomposing your high-level requests into executable robot commands.
Thanks to the LeRobot community for making such an amazing robot accessible. If you’ve contributed to the LeRobot GitHub repo, email hello@vassarrobotics.com for a 20% discount coupon as a small thank-you.
I’d love your feedback! Beyond manufacturing, cleaning up the codebase, and writing docs, I’m considering: a force-controlled gripper, a parallel-jaw gripper, an extra wrist DOF (matching the new Trossen and ARX arms), full force feedback on the leader arm (though that may triple the price), a more affordable version with lower resolution each joint, and a longer-reach variant. Which of these—or something else—would be most useful to you?
You can order it here if you want: https://shop.vassarrobotics.com/products/navrim-robot-that-l.... (Edit: sold out! You can get in on the next batch here: https://vassarrobotics.com/newsletter. I hope we can have your business in the future.)
Looking forward to any and all comments!
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Edit: A quick explanation regarding shipping times (as stated on our shop page):
• The first batch of 20 units, which will be shipped by June 30, is sold out.
• The second batch of 100 units will be shipped by July 15 (unassembled kits) and July 21 (assembled units). The order limit is to ensure we can ship on time and maintain high quality.
For those who have already placed orders: I will reach out individually to ask if you would like to receive weekly progress updates from now until the shipping date.
230 comments
[ 4.1 ms ] story [ 207 ms ] threadA bit of an aside, but how hard is it to get into building RC aeroplanes, compared to FPV copter drones?
Flying is pretty different, though. If you're used to a copter that will just stay put when you release the controls, flying planes will be an adjustment.
That being said, I enjoyed every moment flying my planes. I built and flew quite a few quadcopters but they never felt that free because there's always that control algorithm between the pilot and the motors, while aeroplanes are basically just mapping the movement of the joystick to the servos. I believe the UK has a lot of great local clubs, and I believe that's the best place to get started.
Side note, when your son gets more experience in the field, he might wanna build his own gas turbine to power his planes. And this association based in UK is the best on this planet: https://www.gtba.co.uk
For UK delivery, let me look into how to set up international shipping. Will get back to you by end of the day.
The main difference in building planes is you have to pay attention to center-of-gravity much more; minute differences will make the difference between your plane flying amazingly, like a brick (nose heavy), or not at all (tail heavy). There's also more work to do in setting control linkages and surface throws. But, overall, it's not too tough with most models.
Takeoff with planes can be very stressful the first few times; you have to choose between ground/runway takeoff, which typically results in a very inefficient model due to landing gear drag and is prone to flipping over, throwing the plane by hand, which requires practice and can be quite hazardous with a "pusher" style plane with the prop at the back, and building some kind of bungee launcher, which you then have to set up and lug around.
Then you have to decide how to fly - line of sight or FPV. Line of sight flying is quite an acquired skill and has a very steep learning curve - you basically have to learn to "become the plane" and understand how your control stick inputs are affecting the attitude of the plane without being able to see it very well.
FPV plane flying, while less popular than LOS, is very easy and much more rewarding IMO. The reaction time in all but the most extreme plane stunt flying is much less dramatic than in FPV quads.
And, due to quirks of the general hobby flight control software scene, most hobby FPV planes have a working loiter-in-a-circle setting while most FPV quads have a barely-functional GPS rescue mode and little to no ability to actually hover (it's very rare for an FPV quad to "just stay put"; this is the realm of camera drones).
I fly FPV quads when I need a focus/adrenalin boost and FPV planes when I just want to relax and chill. You can fly planes in an adrenalin style, but they're much more conducive to just looking at the scenery and goofing around. Massive bonus points that most plane builds are almost silent compared to an FPV quad so you don't worry about bothering people so much.
http://wrightbrothersrc.com/products/gambler.htm
If the goal is the flying. You can't go wrong with an easy star. I've crashed mine a million times. You just patch it back together humpty dumpty style with thick CA + accelerant. Bonus points for the prop being in the back, so if you run into stuff you (probably) won't draw blood.
https://mrmpxhobbies.com/product/rr-easystar-3/
Note that the hobby does require some skill w/ flying and need some level of risk management. There are cords that let you plug your transmitter into a computer/fly over a simulation that can help with the former.
I haven't built a balsa wood plane in ages. But so, the glue of choice has changed ? No more balsa wood glue with atrocious fumes ?
How do I buy your kit, please?
https://vassarrobotics.com/
https://www.youtube.com/watch?v=TbDTCwzFeIU#t=52
(I timestamped it to skip the initial voice dialog with the robot but that might be entertaining for some people as well)
It's not exactly on topic (other than fun ideas, begetting fun ideas), but a USB-C/WiFi driven typewriter would be a hoot.
EDIT: Found [0]
And for the reverse ... boom! (click! clack!) [1]
[0] https://www.nutsvolts.com/magazine/article/turn-a-typewriter...
[1] https://www.usbtypewriter.com
Roborock sells a new model that does this [1] but it costs $3,000 and I refuse to pay that on principle when I know it's likely a straightforward model with some unsupervised training.
Also I can probably fix it easier once it (definitely) breaks at some point due to collisions.
[1] https://www.youtube.com/shorts/vHVQxXVgBm4
But I’m routing for you!
Beyond that, things that appeal to me are basically anything which increase the likelihood I can accomplish high dexterous fine motor control skills, for things like tinkering and DIY assembly. I think that would include extra wrist DOF and a longer-reach variant.
Integrated cameras are an interesting idea, but I'd like to be able to swap them out for my own.
My dream is to have some sort of multi-arm table at home. I imagine holding a circuit board, small component, soldering iron, and wire with four robotic arms I control with shaky hands from my laptop. :D
To get better accuracy, if sticking with this kind of RC servo, it's basically required to have two servos per joint to preload each other to kill that wiggle room. It's something I've been calculating, but I just can't figure out a way to offer it at a good price.
Interestingly, for arms that are popular in academia, even when the price goes to $10k (like ARX or Trossen), the wiggle room is still there (better, but still there).
The second thing is low margin. When people are pricing hardware, they usually plan a 50% to 100% margin to offset various costs that happen in the real world. From what I've heard, in extreme cases, some products cost around $100 while they are being sold at close to $1000. I believe in the Prusa printer approach: you design a good product and price it a little bit above cost. So the company grows with the community.
Deep down, there are so many times that I wish I could afford a fancy tool like a Milwaukee drill or a Mitutoyo caliper. And in extreme cases, I really wish I could have a HAAS UMC-400 or even a KERN Micro HD+. Now that I can set the price, I really wish I could make someone get what they want without breaking their bank.
https://www.youtube.com/watch?v=UwrkfHadeQQ
https://m.youtube.com/watch?v=IdAT_SIRK8c&pp=QAFIAQ%3D%3D
https://m.youtube.com/watch?v=63pnz-z_2sU&pp=QAFIAQ%3D%3D
I’ll buy one of these for sure, but I would cheerfully spend 3x the price if it meant being sure of support and repair and software updates for a few years.
I have bins full of exciting devices that no longer integrate, many of which have open source communities, which I just don’t have the time to deal with.
For repairs, the components are inexpensive enough to simply swap in a new one, and you can always find replacements on AliExpress.
But I ended up giving up and going with 400 step stepper motors instead. They're larger, draw more current, and the drive circuitry is more complicated (it can't get simpler than a PWM servo after all). But they're accurate and significantly quieter.
One of the solutions that does not add a bias that I remember is two identical flat gears on the same axis with a spring that tries to rotate them one relative to another. This removes the wiggle room between this composite gear and the next, regular gear. The motor may have wiggle room, but the gears (which carry angle sensors, don't they?) move without wiggling, and react immediately as you reverse the direction. The load is limited though: the beating surface is twice as small, and the friction is higher.
https://img.go-here.nl/unwiggle.gif
One could put those in series too and get even less range of motion in exchange for less wiggling.
One could also duplicate the contraption on both sides. Then could replace the arm with cables (under tension) and control motion further down the arm.
Furthermore it seems you could remove the motors from the moving parts?
Ill let myself out.
https://www.youtube.com/watch?v=GCHXNcpq3OA
Check his channel for servo motor modifications.
If cost isn’t a concern, harmonic drives combined with brushless servos are excellent. I have a few harmonic drive units, and they’re truly amazing.
There was one robot startup (Haddington Dynamics) figured it out how to do it at a higher price. Sadly they've been acquired and shifted directions I think.
Couldn’t you preload with some form of spring?
A spring might also be an option if designed properly. I’ll probably give it a try in July.
However, seeing the chess demo instantly makes me think of that horrible tragedy with the robotic arm breaking a kid's finger. How strong is this to be used around kids?
Initially, I was planning to launch a product using Piper Arms (much more powerful than the current product). But after testing them, I realized they could cause serious injuries if not used properly. So I canceled that version. I still have 8 of them sitting in my office.
Which one is the actual price?
$219 is the unassembled version.
$299 is the assembled version.
When I was just a hobbyist, I had to pay the price on the website. Now that I have some funding to order in large quantities, prices come down a lot. I do the dirty work of sourcing the components so hobbyists don't have to ;)
I would easily pay $1000-$1500 if you put two of these on a wheel base and made it all structurally sound. Extra points if the arms sit at least 1-2 feet of the ground and can reach the ground.
As a roboticist, what I'd vote for, in order, is:
- more degrees of freedom
- interchangeable tools, either an actual tool changer (unlikely at the price point) or a fixed bolt pattern with electronic passthroughs
- better joint sensing, e.g. absolute encoders, joint torque sensing
- fingertip force sensing
The post says "kit that keeps LeRobot SO-101’s kinematics" so it's probably very similar to [1] namely 5DOF and a gripper, using STS3215 servos [2]
> As a roboticist, what I'd vote for, in order, is:
As they are making a robot at the $219 price point, I very much doubt they have the money to add anything to the design.
[1] https://huggingface.co/docs/lerobot/so101 [2] https://uk.robotshop.com/products/magnetic-encoding-servo-st...
“I’d love your feedback! Beyond manufacturing, cleaning up the codebase, and writing docs, I’m considering: a force-controlled gripper, a parallel-jaw gripper, an extra wrist DOF (matching the new Trossen and ARX arms), full force feedback on the leader arm (though that may triple the price), a more affordable version with lower resolution each joint, and a longer-reach variant. Which of these—or something else—would be most useful to you?”
As for hardware features, we can’t add much to the current model since, as you mentioned, we are running on very thin margins. We’re gathering suggestions primarily for future models.
• A tool changer is a great suggestion. A few of my friends are working on kinematic couplings, which would be ideal for this. I’ll need to give some thought to how to pass electrical signals and power to the tool, while also keeping it lightweight.
• Could you share what functionality you want in terms of encoders? The ST3215 uses 12-bit magnetic encoders, which can retain position after power loss. Are you looking for higher resolution? For torque sensing, if the order volume is large, I can add this for just a $20-30 price increase.
• Finger tip force sensing: Is this for applications like picking up an egg?
You'd also ideally add torque sensing at the joints because it opens up a whole world of control techniques that you can't get with just joint position sensing. You can do compliance or force control, which lets the arm act as if it had a spring at the joints, so when it hits something the impact is nice and gentle, and importantly, so you can do things like e.g. a bolt insertion task where you have to control the position of the arm in x and y but you want to exert a small positive insertion force in z.
Yes, but even for picking up rigid objects this turns out to be very useful. If you're picking up an eg, you want to exert a controlled positive grip force that's big enough so you don't slip but not so big that you crack the egg. If you're picking up a bolt, you definitely won't break it but many robots are strong enough to deform the threads. If you're picking up something slippery, it would be great to try to detect the slip by touch. And so on. Often, you don't know exactly how big the object is or how flexible/brittle it is and it's hard to judge by vision alone whether the fingers are even in contact with it, or if they are how much it's being deformed, so being able to control grip force is very useful. Add force and position sensing to the grippers and you can judge how deformable the object is and make decisions accordingly.Or if you're folding clothes or handling cables or wires or anything else flexible, you really need to have a sense of touch. You can't really do these tasks very well with position sensing and vision alone.
Another idea: Maybe add a passive mounting adapter and power leads at the end effector so people can add their own vision or lidar sensors, and just let them connect via bluetooth, so ...
What you do need is an articulated rigid body model that you can import into e.g. NVIDIA Isaac Lab or Gazebo. The availability of a good digital model is a HUGE selling point.
Pardon my naïve imagination but, would stackable joints work - with same connector as the extremity tooling ? The joint would be a standard piece and more degrees of freedom would just mean stacking additional joints. I suppose this has already thought about...