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 [email protected] 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.
Thank you so much for everyone’s support. My top priority now is to get all the orders shipped on time and with high quality.
$200 is a really nice entry-price point. If I'm being honest, I'm marginally interested in this, but doubt that I'd actually use it too much. But the price point is justifiable for someone who is just interested in it from a learning point of view (if I bought this, used it a few times and learned a bit more about AI as it relates to robotics, it'd have paid itself off easily).
Rooting for you to succeed.
1. Keep the price similar while adding new features, such as a torque-controlled gripper. 2. Re-examine design decisions to see if we can offer a similar product at an even better price.
And you've got an excellent gradient to keep growing!
All the best!
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).
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.
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.
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.
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.
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
For repairs, the components are inexpensive enough to simply swap in a new one, and you can always find replacements on AliExpress.
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.
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
• 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 you don't have to route signal cables?
FYI, I am a space roboticist by trade and I teach a graduate level class in robotics at the University of Maryland.
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...
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...
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.
“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?”
But I’m routing for you!
I'm sure there's an extra fee but it's sometimes just impossible to order things if you're a big organization from small sites like this.
Also, the servos we are using actually have a version that has lower torque/force output, which would be safer for students but also limit what they can do with it. Would you be interested in the "safer" version for classes?
I love the product though, and I appreciate your input!
If you fully control the environment: exact positions of arm-base and all objects which it interacts with - you can just replay the trajectory on the follower-arm. No ML necessary.
You can use LLM to decide which trajectories to replay and in which order based on long-horizon instruction.
Just a quick difference I need to point out as it's critical product spec: leader arms are using 7.4v version of ST3215 (various gear ratios) while follower arms are using 12v version of ST3215. (12v version have higher peak torque at close to 3 Nm)
for anyone following along at home: THIS IS NOT A SMALL DETAIL!
there are 12 servos total and 4 different types of 7.4 volt ones in the box. make sure you use the right one, or else you'll waste precious time to reassemble the arm.
If you go beyond pre-recorded "blind" trajectories into more robust task-policies (which you would have to train from many demonstrations) then cameras become necessary to execute the sub-task.
A bit of an aside, but how hard is it to get into building RC aeroplanes, compared to FPV copter drones?
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.
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 ?
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.
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.
- you recorded precise arm-movement using leader-arm - for each combination of source- and target- receptacles/board-positions (looking at the shim visible in the video, which I assume ensures the exact relative position of the arm and chess-board);
- the recorded trajectories are then exposed as MCP-based functions?
Bought the kit. Thank you for the great price! Are table-clamps included?
I thought your product page could use a slightly nicer UI. - I'm building an app that let's people spin up multiple variations of their pages and easily implement new UIs. - I like to put HN websites through it whilst I'm training it up to see if I can improve them.
here's what my app came up with for your site: https://streamable.com/vbby9q
If you want the html + css, it's here free of charge, I've split each one up with a ## Variation 1/2.. etc.. just let me know what you think - https://pastebin.com/WGNieVmq
For stuff like this, it would be cool if you had a hosted demo of what you clicked through in the video.
Would you please provide more info on what's involved for the kit? Ranges are okay.
This product is largely based on the SO-101. With all the improved designs, let's say it would still take 2 to 4 hours, depending on your experience.
The price point is crazy good. If it indeed can be so flexible in learning a number of things, just take my wallet. Having an extra hand for N number of DIY projects is invaluable.
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
How do I buy your kit, please?
https://vassarrobotics.com/
1. Would we be able to control it deterministically via an API, rather than relying on LLM?
2. What is the latency on this? Do you think it would be fast enough in deterministic mode to play ping pong?
Nowadays, if you’re running a 2–3B parameter foundation model on a standard computer, you’ll probably get a rollout frequency of 1 to 10 Hz. ACT would be faster, but I still don’t think it’s fast enough.
Just one question: does the power supply have a 220/240v option (I'm in Australia)?
When you are placing the order, make sure you put the shipping address to Australia address and so that I will know I need to source corresponding power supply.
Congratulations on a great launch!
The most important link to get started is probably https://github.com/huggingface/lerobot
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
Can I order one where I 3d print the in printable bits and you supply the rest. Not to save money but to have a more tweakable design.
Which one is the actual price?
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 ;)
$219 is the unassembled version.
$299 is the assembled version.
It will probably be available in late July. We’re expanding the team, so we might be able to offer it sooner.
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.
As long as it’s within this year, I’m sure we can arrange it.
For software, even the best policy in the industry struggles a little bit (the arms they are using is about $10k each): - https://youtu.be/Oa19cq_MxE0 - https://www.dyna.co/research
In conclusion, for hardware, it might work if you have two of the arms; for software, it's probably too hard to collect enough data to make it work.
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.
I wonder if we should just change the format to "YC YY", e.g. "YC 25" for 2025, and stop including a letter for the batch.
"(YC Spring 2025)" is too long for HN titles!
Or dots, for extra 1337ness - 2025.1, 2025.2, etc.
Notation is a funny thing...unimportant and important at the same time
Congrats on shipping!
Thank you!
I can personally not solder, but I would love to have two arms that can just do it for me.
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)
this page design is so beautiful