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CARA 2.0 – “I Built a Better Robot Dog”
- globalnode 5mo agoits a fantastic achievement and the guy seems amazingly talented, is it a big achievement? leaves me feeling flat... maybe im just jealous lol.
- deleted 5mo ago[deleted]
- Animats 5mo ago3 DOF per leg, so it needs 12 motors and controllers. Getting that under $1000 is nice. Here's the US$18 motor: [1] Those things are getting really cheap. He did have to rewind it, though, for more turns with thinner wire. The manufacturer mentions that you can order with "custom Kv", which means you might be able to get a different winding from the factory if you order a reasonable quantity. Especially if you tell them that makes them "robot motors". Motor overheating might be a problem. The dog, just standing, has its motors stalled under load, converting power to heat. Drones don't do that. Temperature feedback would help if this thing has to operate for extended periods. Remember yesterday's article on humanoid robots and their cooling problems. The motor controller is nice too, and cheap at $49. Needed fixes to the firmware, but that's not surprising at the price. High performance motor controllers used to cost about $1000. Repurposed drone technology has done wonders for legged robots. We're not quite at the point where limb drive hardware is off the shelf, but it's way better than it used to be. [1] https://www.xntyi.com/tyi-5008-kv335/kv400-high-speed-brushless-motor-for-fpv-drone- https://www.xntyi.com/tyi-5008-kv335/kv400-high-speed-brushl...
- rmast 5mo agoIf you read the epilogue, they weren't able to achieve the under $1000 price goal. Total cost ended up being around $1,450. Pretty good price reduction compared to CARA 1.0 though. Hypothetically if I were to want a quadrupedal robot to experiment with it's not an impulse buy/build, but getting closer to that point... whereas $3000+ is a hard pass (e.g. Apple Vision Pro territory).
- regularfry 5mo agoIt's $1450 if you discount the construction time, as ever. Which ordinarily wouldn't be worth commenting on, but in this case it means rewinding 12 motors which just sounds like an exercise in tedium and hand pain.
- 15155 5mo agoOnly because they didn't know how to ask the vendor to do it for them. I guarantee this vendor would be delighted to make them to spec at a 1ku volume, max. Rewinding isn't even a meaningful SKU distinction or line retool, it's a configuration parameter. At 12 motors per product, it's easy to hit MOQ.
- dezgeg 5mo agoReminder that this was a student project.
- drzaiusx11 5mo agoThere are inventor programs that'll literally ship you to Shenzhen to build connections to manufacturing sites and even provide you with a liaison, etc. I only know this because I was once in a program that did exactly this.
- modeless 5mo agoMind linking some?
- drzaiusx11 5mo agoHAX Ventures (Formerly HAXLR8R) https://hax.co/ https://hax.co/ TroubleMaker (Conquer! program) https://troublemakershenzhen.com/member/apprentice-membership/ https://troublemakershenzhen.com/member/apprentice-membershi... Seeed Maker Camp https://www.seeedstudio.com/blog/2024/01/15/introducing-maker-camp-in-shenzhen https://www.seeedstudio.com/blog/2024/01/15/introducing-make... I was an alumni of HAXLR8R before the rename.
- barrenko 5mo agoCould I pursuade you to expand on "Repurposed drone technology has done wonders for legged robots." ? Thanks!
- franciscop 5mo agoLook at the original video/article, they used drone motors for the robot dog, by reusing the rotor/stator and rewinding the coils manually.
- cyanf 5mo agoFor legged, you want high torque and backdriveability (for shock absorption). Agricultural drone motors like the eaglepower 8308 are ideal. They’re cost effective, (~$80 from aliexpress) & you can pair them with a 3d printed cycloidal drive to fulfill both requirements. Industry actuators are an order of magnitude more expensive than this. Extra: If you go down this path, you’ll need a driver. The Xdrive is frequently recommended, but there’s a clone that’s significantly cheaper: https://makerbase3d.com/product/makerbase-xdrive-mini-high-precision-brushless-servo-motor-controller-based-on-odrive3-6-with-as5047p-on-board https://makerbase3d.com/product/makerbase-xdrive-mini-high-p...
- cyanf 5mo agoMotor: https://www.aliexpress.us/item/3256804897857573.html?gatewayAdapt=glo2usa4itemAdapt https://www.aliexpress.us/item/3256804897857573.html?gateway... The 90KV version is what you want.
- JKCalhoun 5mo ago"The 90KV version is what you want." You mean the "KV90 color" of course, ha ha. That we live in an age where "agricultural drone" is even a word pairing…
- lastdong 5mo agoThis is pretty cool, thanks for sharing. I wish there was a (mostly) 3d printable Cara mini, but I’ll start with Cara.
- regularfry 5mo agoIt doesn't have to stall to stand still. Or squat, at least. With that leg layout it can safely rest against its backstops when the motors switch off. The drive motors, anyway. The hip motors probably still need to hold vertical balance, but that's intermittent, not a stall load.
- regularfry 5mo agoOh, just thought in addition to this: you could define a standing locked position, too, if you drive the capstans to full rotation inwards so the knees only just reverse, and put extra backstops there. Not sure what that would do on uneven ground, I think you'd need to balance centrally over three legs and let the fourth hang loose.
- Tade0 5mo ago> Motor overheating might be a problem. The dog, just standing, has its motors stalled under load, converting power to heat. The Nao robot[0] had this exact problem and of course no way to fail gracefully. I recall checking its basic functions with my lab partner in college. I looked away for a moment and that was when it went down hard. Me and the other guy locked eyes in an "oh fuck" moment, as the robot was expensive and our thesis supervisor went through quite a lot of paperwork to have it funded. Fortunately it was intact and none of us mentioned this incident to anyone. [0] https://en.wikipedia.org/wiki/Nao_(robot) https://en.wikipedia.org/wiki/Nao_(robot)
- JKCalhoun 5mo ago"Temperature feedback would help if this thing has to operate for extended periods." Rather than thermistors all over the place, perhaps an onboard program could calculate motor temperature by integrating current sent to each over time—assumed some degree of cooling (and perhaps here a single temperature sensor might measure ambient temperature of the environment… or could just assume "indoor temperature").
- fennecfoxy 5mo agoI would rather just have temperature sensors over the place. More reliable.
- deleted 5mo ago[deleted]
- Animats 5mo agoFor a toy, you might just have a simple thermal fuse.[1] ($0.78 from DigiKey, plus "tariff may apply if shipping to the United States". About $0.15 on Alibaba, if you order enough.). For a working machine for field use, you want feedback to the controller, so it can slow down or rest or something when it overheats. [1] https://www.digikey.com/en/products/detail/cantherm/RT121/28383650 https://www.digikey.com/en/products/detail/cantherm/RT121/28...
- rmast 5mo agoTrain it like Disney’s Olaf where it can adjust how it walks/stands to keep motor temperature under control.
- Gracana 5mo agoThat’s how industrial VFDs do motor overload protection, they just keep track of heat accumulation (based on current) vs dissipation (based on fan speed) and fault when a threshold is reached. Probably there’s more nuance to it, but that’s the gist of it.
- squarefoot 5mo agoNot my field so I'm likely using the wrong name for the concept, anyway, don't stepping (bistable) brakes exist? I mean, one pulse to one pin engages and one pulse to another pin disengages, just like step relays, with the current consumption being zero when it's not operated so that the robot can be kept indefinitely in resting position without wasting energy to keep motors stalled.
- Animats 5mo agoStepping motors are not good at stationary power consumption. They use power even with no load on them. Brakes for robot joints are common in industrial robots. They're usually part of the emergency stop system. If power fails, the controller crashes, or someone pushes the emergency stop button, spring-driven brakes lock all major joints to stop all motion.[1] That might be useful in a quadruped, which can park without active balance. [1] https://www.techbriefs.com/component/content/article/28812-choosing-the-right-brake-for-robotic-applications https://www.techbriefs.com/component/content/article/28812-c...
- Springtime 5mo agoI like the wide layout of the site but just on a readability front on a widescreen monitor after the opening more narrow paragraphs it changes to full width text layout and those could benefit from a `columns: 2` in CSS to split them since reading long width paragraphs is a bit difficult.
- npodbielski 5mo agoSeeing stuff like this, I am wondering why the hell I am doing software. This is much cooler than CRUD for DB data nth time.
- igleria 5mo agoSame. I do have an excuse due to lack of space in my apartment, but once we move...
- voidUpdate 5mo agoHardware can be quite expensive and time-consuming, instead of just writing code (free) and running a command to deploy (quick) you have to get hold of good motors (expensive) and design and manufacture parts (slow)
- npodbielski 5mo agoYou do not have to convince me! I already love it!
- JKCalhoun 5mo agoIf you have any spare time…
- fennecfoxy 5mo agoThere's the mech/EE equivalent of crud, too. Plus the demand is higher for software than it is for hardware most of the time. Pretty hard to find jobs in robotics compared to all the various kinds of software.
- jitler 5mo ago[dead]
- layer8 5mo agoYou could do non-CRUD software instead.
- 5mo ago
- RoxiHaidi 5mo agoThat's impressive! good job
- pbmonster 5mo agoThe jumps are pretty impressive, this thing has some power. I'd be very curious how fast you could get this dog with some reinforcement learning for a proper transverse gallop gait - and if it converges towards a gallop naturally, or if it discovers some other fast gait patterns during learning. Depending on the max speed of the motors/legs, giving it longer foot pads might be necessary for a good gallop. Intuitively, it looks a bit... "low gear" in the videos.
- SamBam 5mo agoI wonder how accurate a virtual model could be made of this, which could be iterated on millions of times faster. My first project as a research assistant in AI was doing evolutionary algorithms on Khepera robots, which had a virtual Java implementation. We were able to evolve some pretty cool behaviors, although I don't know what would have happened if we had uploaded them into a physical Khepera robot.
- pbmonster 5mo agoI'd expect pretty good results from simulation until you start bending/deforming the limbs or until the foot pads start slipping. I also wonder if you can read the impact force from the legs with the ground from the motor controllers (should be able to infer that from motor current + leg displacement). Learning to gallop without "feeling" the legs impacting sounds extremely difficult.
- KaiserPro 5mo agoI love Aaed. Not only are the youtube video excellently produced and well researched, the website is a mine of information. This is spectacular as a reference, which youtube isn't
- aaron695 5mo ago[dead]
- shutterkiller 5mo ago[flagged]
- abelsm 5mo agoAwesome video. It's interesting, informative, and entertaining. Founders I talk to that are doing hardware, broadly speaking, say it's a competitive advantage as it's not as crowded. Content like Aaed's will hopefully nudge more people into it.
- matt_kantor 5mo agoYou may also enjoy https://www.youtube.com/@StuffMadeHere https://www.youtube.com/@StuffMadeHere.
- JKCalhoun 5mo agoHa ha, that guy with his ever-underwhelmed wife. (Aren't we all this guy?)
- elictronic 5mo agoIt’s because hardware has so many limitations that get glossed over vs. software. Manufacturing issues, sourcing issues, regulatory timelines, physical returns, inventory management, and oddities in the physical world are much easier to spot by an investor. Nikola motors and hills? It can take 6 months once your product is finished to be legally allowed to sell it and even then it could be forced to be recalled or be redesigned. It’s a much more difficult environment to deal with vs I spent a few months throwing together this slop code, thanks for my multi-million dollar buyout.
- crimsoneer 5mo agoAs a man who always desperately wanted a Sony AIBO (and is now only put off by the bonkers $300 a year AI subscription), I am unduly excited.
- 3form 5mo agoPeople are all discussing the technical aspects of the device, which is great and all, but forgetting the one aspect I am in awe of: how googly eyes once again make everything 300% better.
- defrost 5mo agoA truism that sadly not all are onboard with: https://www.bbc.com/news/articles/c1wl5jp94eno https://www.bbc.com/news/articles/c1wl5jp94eno
- tamimio 5mo agoQugv looks cool and futuristic and has that wow factor, great in expos and milking investors’ money, but practically speaking? They are useless, they have the bad mobility of UGV (compared to UAV), and the bad endurance of UAV (compared to UGV), so they are the mix of worst of both worlds. There’s also other technical issues but yeah, only good for marketing, no matter how they try to push them in defense or whatever, they never materialize.
- Michael666 5mo ago[dead]
- tantalor 5mo agoRewinding the motors manually to increase torque is cheating if you can't scale that up and keep the cost down. And, if you can scale that up, then why even mention it? It's not relevant.
- fennecfoxy 5mo agoYeah agree. Having to rewind the motors just adds yet another task to the list for someone trying to build this thing. Also BLDC based motors in bots seem to be popular now, used to be steppers and harmonic drives from what I remember reading. Idk why electrostatic actuators aren't getting more popular like HASEL and a few papers on ones using fiber pumps come out recently. I suppose the danger that the high voltages present hmmm. But surely we can replicate muscle fiber actions magnetically, just need some sort of crazy micro manufacturing process to make the magnets.
- fc417fc802 5mo ago> surely we can replicate muscle fiber actions Considering what muscle fiber looks like on the molecular level you're literally describing nanotechnology and the associated nanofabrication techniques. Surely it's possible to do but we don't seem to be there just yet.
- fennecfoxy 5mo agoYeah for sure, I have read up a decent but on muscle fiber structure & the ATP (I think) ratcheting system. With nano or at least micro manufacturing technology could make millions of ultra small magnets across a strand and try to use them to hook/unhook and shift two surfaces against each other. I even thought it may be cool to try experimenting with piezoelectrics - could have two sub-fibers made of a piezoelectric material with a sawtooth type shaped etched in then see if applying signals that "walk" up the sub-fiber pulls them along each other. Whelp, if I ever won the lottery I'd spend my days trying out things like that I suppose.
- proee 5mo agoI'm sure he could contact a supplier that would change the windings for the same price if he went into production mode. So doing this for his prototype doesn't seem unreasonable. He's under a massive time crunch per his school semester to get this project out the door.
- dyauspitr 5mo agoAll I can think of is slippage and the lack of precision though I know I’m wrong because he spends a significant part of a previous video explaining why it isn’t an issue.
- leoc 5mo agoAs it so happens 'cara' https://en.wiktionary.org/wiki/cara#Irish https://en.wiktionary.org/wiki/cara#Irish is the Irish [Gaelic] word for 'friend' (probably related to words like Italian 'caro' etc.) so CARA is not a bad name for a robot dog!
- erwincoumans 5mo agoVery nice project. If you like this, the Pupper quadruped robot project by Stanford University is also interesting, with RL training pipeline as well and well-documented open source instructions for 3d printing etc. https://pupper-v3-documentation.readthedocs.io/en/latest/guide/building.html https://pupper-v3-documentation.readthedocs.io/en/latest/gui...
- peterleiser 5mo agoThat is very cool. Their kit is $3,000 and the unaffiliated kit is $2,350, so definitely a commitment.
- zzzeek 5mo agothis guy is going to get a high paying job at some defense contractor somewhere and we'll never see anything he does again.
- 4gotunameagain 5mo agoOh you will see it eventually, but it will be the very last thing.