I've watched and re-watched Aaed's videos on the capstan drive, it's great stuff. High speed, high torque, compliance, effectively no backlash. It's fascinating to watch a legit engineering mind at work.
It's amazing what he's done in terms of the robotics, and the presentation of it to the viewer. I'm amazed at the quality of cinematography on the internet these days.
The implications of the tools we now make available for use in our own personal workshops are still being discovered, and will be for some time.
I watched this last week and my jaw was on the floor. He's both a great technician, and he has the personality to make it interesting. He walked through his testing strategy far enough that you could understand his methodology and the thought process behind it, but didn't belabor it by making us watch it all. Banger!
What is the power consumption of these robots? I often wonder how limited and viable autonomous robots really are. When I look at Tesla's Optimus or Boston Dynamics' spectacular robots, how quickly do they need to be recharged?
I think he'll have success with youtube/vlogging more than getting into the corporate world honestly - especially with some healthy sponsorships and great projects like this.
Breaking Taps on YouTube did a really awesome video on a somewhat similar mechanism (I'm no mechanical engineer haha, it was new to me!), rolling contact joints. I love the idea of using string/ropes. Worth checking out as well if this kind of stuff interests you! https://www.youtube.com/watch?v=TQiLLcumqDw
Thanks for sharing this! What a treat of a video. It's a fun project, and it's presented very well. This guy has a talent for communication - the video was super clear and well explained. I really admire that ability and I want to get better at it.
Fascinating! I want to get into this type of stuff. But I have no idea where to start, I just have just a CS degree and 3 years experience as a developer.
I remember a post previously related to him here on HN but I am surprised at how I forgot about him and how cool he is to build all these incredible stuff and also teaches in his videos. I am subscribing so that I never miss anything from him again.
Very cool robot dog and interesting video!
Can the dog climb stairs? Isn't capstan drive temperature sensitive, e.g. the ropes will be shorter in cold and longer in warm wheather?
New here and just stumbled upon this. Seen these "robodogs" live in Vegas mining conference. The usage is picking up, their functionality and range of movement is so much more advanced now, and the list of actions they can complete much more complex. Awesome stuff!
What a horrible video is this, with the robotic translated AI voiceover?
Update: Ah, weird, if I watch the non-embedded one on youtube it is the original in English with normal sound. It's the one embedded on his web site which has AI translation to German.
How do we make such robots intelligent? Like you only tell it to learn to jump the rope and then it goes through trial and error(s) to figure out a way to do it, and if it can’t and needs a physical upgrade then it tells you that? (Like a certain gear ratio etc)
It might be fun to optimize the shape of the rolling contact surface of the capstan drive away from cycloid to make it even better suited for specific application, like a robot dog leg that smoothly runs for miles.
It's just a gut feeling but I'd trust a feedback based backlash elimination mechanism more than rope based, especially in the long run and/or with a large deployed base.
> Programming takes the cake for what is both my most and least favourite part of any build. Nothing quite makes you pull out your hair and ask yourself, 'What the heck have I gotten into?' Like spending weeks programming a robot that just won't work. Eventually though, you fix that one line of code that makes all the difference. And then it's smooth sailing. Well, kind of.
I feel this deeply, also this whole video is quality content.
There is a weird mixture of hope and dread in me as I watch this. I am ridiculously excited over a person like me being able to mess around with something that, until recently, was gated behind, well, a lot of hard problems to overcome ( I am only now slowly getting through old Peter Scott's robotics to get some perspective ). By comparison, it should be so much easier to explore aspects of robotics that may go beyond strict math and engineering.
this guy's work is pretty amazing
I whole heartedly believe that I'll own a gang of (armed) quadrapets for home/property/personal protection within the next 10 years. I'm equally worried that once these become commodities they might be worse than an electric scooters have become to us bipeds on sidewalks but on balance I can't wait
The video is the epitome of applying solid engineering principles. Where most stop at a minimal viable working example, it sails past that and gets real work done solving foundational problems, using a waterfall approach that expands leverage at each level of abstraction. Complete with outside-the-box thinking and insights which help save the viewer from repeating unnecessary steps, so that the end goal is reachable using modest tools and readily available materials.
I would gladly work with Aaed, and I must admit that I am jealous that he and his friends are living out the dreams that my friends and I had in the 1990s.
-
The Boomers didn't quite understand what we were trying to accomplish, as they had already done the important work of manifesting the equality that had previously been a dream in the US, so these sorts of innovations were gravy. But Gen X was raised on Star Wars, so will not be withholding mental energy from future generations. Unfortunately we are also victims of trickle-down economics, so have little to pass forward except for wisdom gleaned from the school of hard knocks.
We had everything we needed to build these exact types of projects except for the time and resources that were hoarded by our elders. So the vast majority of us worked our lives away, barely making rent by prospecting the internet as miners for people with money, without ever striking gold in the vast majority of cases. Then watched as the fruits of our labors were used to build McMansions, expand monopolistic enterprises like private equity firms, or be simply wasted on frivilous expenses instead of reinvested in automations to create residual incomes. This led to us developing mental health issues like addiction due to the misalignment between the lives we had to live vs what might have been.
Then we lost our heroes, like when Y Combinator went from an indie startup funder to a vetting VC like all the rest. And when Elon Musk pulled up the ladder behind him after accomplishing so much, then used his wealth to dismantle the social safety nets which make indie work possible. I don't believe that these statements are political, as they objectively describe the unwritten history of how some became so wealthy while most struggled, and the irony that I write this as I stand on the shoulders of those fallen is not lost on me.
Now we have everything we need to build R2D2 and C3P0 right now, today.
So I'm hopeful that the next step will be to create a meta economy within the status quo that distributes resources outside of the artificial scarcity created by the previous dominant systems of capitalism, socialism and communism. I believe that a gift economy loosely resembling solarpunk has the potential to liberate humanity from forced labor so that every individual has the opportunity to self-actualize in a reasonable time frame and still experience the joys of leisure time and youth.
In practice, this will expand wealth redistribution models like Patreon and the WiX Toolset maintenance fee under an umbrella similar to the Humble Bundle, to level out long-tail effects and socialize gains while privatizing losses. Note that this works exactly the opposite of how most major economies work in the world, with the exception of nations like Norway which uses its sovereign wealth fund from nationalizing its oil companies to pay its citizens a pension that may someday become UBI.
I realize that these points are mostly excuses and platitudes. But they are in no way meant to diminish the efforts of hackers - on the contrary, they are intended to bolster them by adding meaning to the work and convey why it's so important to those that came before.
So I write this out today to record in the annals of history that the nature of the problems we face is no longer technical, but spritual.
CARA – High precision robot dog using rope
(aaedmusa.com)1034 points by hakonjdjohnsen 23 July 2025 | 181 comments
Comments
The implications of the tools we now make available for use in our own personal workshops are still being discovered, and will be for some time.
https://www.aaedmusa.com/
It definitely gives off Elysium (film) vibes.
Also, I wonder how resistant this mechanism is to wear and fatigue.
Breaking Taps on YouTube did a really awesome video on a somewhat similar mechanism (I'm no mechanical engineer haha, it was new to me!), rolling contact joints. I love the idea of using string/ropes. Worth checking out as well if this kind of stuff interests you! https://www.youtube.com/watch?v=TQiLLcumqDw
Time to raise my own bar.
Update: Ah, weird, if I watch the non-embedded one on youtube it is the original in English with normal sound. It's the one embedded on his web site which has AI translation to German.
I feel this deeply, also this whole video is quality content.
Geordi LaForge reminds me of Aaed.
Edit: And yes of course, in hindsight, you don't build a leg unless you're planning to build a thing with legs.
The video is the epitome of applying solid engineering principles. Where most stop at a minimal viable working example, it sails past that and gets real work done solving foundational problems, using a waterfall approach that expands leverage at each level of abstraction. Complete with outside-the-box thinking and insights which help save the viewer from repeating unnecessary steps, so that the end goal is reachable using modest tools and readily available materials.
I would gladly work with Aaed, and I must admit that I am jealous that he and his friends are living out the dreams that my friends and I had in the 1990s.
-
The Boomers didn't quite understand what we were trying to accomplish, as they had already done the important work of manifesting the equality that had previously been a dream in the US, so these sorts of innovations were gravy. But Gen X was raised on Star Wars, so will not be withholding mental energy from future generations. Unfortunately we are also victims of trickle-down economics, so have little to pass forward except for wisdom gleaned from the school of hard knocks.
We had everything we needed to build these exact types of projects except for the time and resources that were hoarded by our elders. So the vast majority of us worked our lives away, barely making rent by prospecting the internet as miners for people with money, without ever striking gold in the vast majority of cases. Then watched as the fruits of our labors were used to build McMansions, expand monopolistic enterprises like private equity firms, or be simply wasted on frivilous expenses instead of reinvested in automations to create residual incomes. This led to us developing mental health issues like addiction due to the misalignment between the lives we had to live vs what might have been.
Then we lost our heroes, like when Y Combinator went from an indie startup funder to a vetting VC like all the rest. And when Elon Musk pulled up the ladder behind him after accomplishing so much, then used his wealth to dismantle the social safety nets which make indie work possible. I don't believe that these statements are political, as they objectively describe the unwritten history of how some became so wealthy while most struggled, and the irony that I write this as I stand on the shoulders of those fallen is not lost on me.
Now we have everything we need to build R2D2 and C3P0 right now, today.
So I'm hopeful that the next step will be to create a meta economy within the status quo that distributes resources outside of the artificial scarcity created by the previous dominant systems of capitalism, socialism and communism. I believe that a gift economy loosely resembling solarpunk has the potential to liberate humanity from forced labor so that every individual has the opportunity to self-actualize in a reasonable time frame and still experience the joys of leisure time and youth.
In practice, this will expand wealth redistribution models like Patreon and the WiX Toolset maintenance fee under an umbrella similar to the Humble Bundle, to level out long-tail effects and socialize gains while privatizing losses. Note that this works exactly the opposite of how most major economies work in the world, with the exception of nations like Norway which uses its sovereign wealth fund from nationalizing its oil companies to pay its citizens a pension that may someday become UBI.
I realize that these points are mostly excuses and platitudes. But they are in no way meant to diminish the efforts of hackers - on the contrary, they are intended to bolster them by adding meaning to the work and convey why it's so important to those that came before.
So I write this out today to record in the annals of history that the nature of the problems we face is no longer technical, but spritual.