I spent some time on legged locomotion back in the 1990s. It was clear then that you wanted torque control, and I did some work on the theory for that, trying to solve it from first principles, not machine learning. Got some nice theory and a patent out. But the parts just weren't there to build such things. As the article points out, the key to this is motor back-drivability. The final drive has to survive shock loads, and it has to dump forces into the motor, where the magnetic fields can take it. As I've quoted before, "you cannot strip the teeth of a magnetic field", a comment from early General Electric locomotive sales. (Locomotives are Diesel-electric, not Diesel with a clutch and shifting gearbox, because the clutch required is huge. Yes, it's been tried.)
That's something few areas of engineering cared about, with the exception of aircraft flight control systems with mechanical backup.
Pneumatic actuators looked promising, but proportional dynamic valves were big, heavy, and about $1000 each. Linear motors (not ball screws) looked like the coming thing back then, as 10:1 power/weight ratio had been achieved.
But that technology never got much further, and Aura, the biggest player, collapsed in a financial scandal. Series elastic actuators were (and still are) a race between the spring compressing and the ball screw motor starting up. Hydraulics were too clunky; Boston Dynamics built a 400 pound mule, but the Diesel power pack never worked.
Direct drive pancake motors were used by some SCARA industrial robots, but those were too big for leg joints.
I thought someone would crack the direct drive problem eventually, but nobody ever did. We're still stuck with some gear reduction.
Some of the exotic ideas for muscles mentioned in this article go back that far. The McKinney muscle is old, and not too useful. There was some interest in electrorheological fluids, fluids whose mechanical properties change when an electric field is applied. That didn't become useful either. Shape-memory alloys were a dead end; liquid cooling can overcome the slowness problem, but not the inefficiency problem. Everybody went back to good old electric motors, although they became 3-phase AC instead of DC. It helped that the drone industry made 3-phase motors and their controllers small, cheap, and powerful.
Academic robotics groups were tiny. MIT and Stanford had less than a dozen people each.
Progress required hundreds of millions of dollars for all that custom engineering and R&D. The level of effort just wasn't there. Nor would throwing money at the problem prior to machine learning have led to useful products.
It's impressive what's been accomplished in the last five years. It took a lot of money.
Fraterkes 2 hours ago [-]
Silly question maybe, but didn’t Boston Dynamics have videos of bipedal robots doing acrobatics / running ~7/8 years ago? Kinda looked like they “solved” locomotion then
Animats 2 hours ago [-]
Their approach required pre-computation and simulation before execution. If you watch their videos carefully, you can see the advance planning work on some of the screens.
Fraterkes 2 hours ago [-]
I can understand pre-computation making the “software” problem of locomotion easier, but how does it help with the hardware problems laid out in the article, ie repeated very high load over a very short amount of time?
bryanrasmussen 12 minutes ago [-]
overclocking a CPU might make it seem that you solved something and gotten better performance, but sooner or later it breaks down, as I read the article I believe that pre-computation essentially allows you to "overclock" the hardware, and make it seem that you have solved the problem of locomotion when what you have actually done is made something that looks impressive for a very much shorter of time than is usually used to calculate what the hardware can bear.
on edit: apologies if my analogy is not the best.
Animats 1 hours ago [-]
BD used hydraulics for a long time. Works, but inefficient. You have to carry the actuators, the tank, probably a hydraulic accumulator, the pump, valves, and the power source for the pump. That's why BD's machines were so big. Someone at Google said "We need to have a conversation about hydraulics", and the dog robot in 2019 was the first all-electric machine.
aDyslecticCrow 25 minutes ago [-]
plenty BD clips of old atlas include oil lines bursting and showing the room with oil.
it's indeed a mess.
Joel_Mckay 1 hours ago [-]
BD was under business pressures, and a computerized automaton doing baked ninja back-flips with servos is more impressive than inexpensive FK/IK demos dead-lifting 1000lbs. Google broke that company with their opinions.
Even if private labs have a viable platform solution, people won't care unless they can clone it for free. Not a lot of incentive for design change, but building Kryten 2X4B-523P would be hilarious. =3
snovv_crash 2 hours ago [-]
I feel like the loads would suit electrostatic motors quite well if those could be made appropriately compact.
RaSoJo 38 minutes ago [-]
How can we trust this article or the company if the writer/so-called chief engineer decides to hide himself behind an AI avatar?
Nobody has a problem with companies using AI to edit articles, create images.
But when even the writer is an AI persona, the trust factor gets destroyed.
vova_hn2 28 minutes ago [-]
Probably a dumb question, because I know nothing about robotics, but:
> The "Zero RPM" Problem
> When a robot bends its knees to stand, the motor must constantly fight gravity. There is no skeletal structure to lock against. To an electric motor, holding a static load—known as stall torque—is the most punishing state possible.
Why not just add some kind of brake that can fully or partially lock the joint?
thrownthatway 6 minutes ago [-]
Complexity, weight, failure modes, wear, maintenance, support burden of legacy parts.
Also the brake components are never in the same plane as the drive components, so now you have additional forces to engineer for.
AntiUSAbah 16 minutes ago [-]
You need to keep balancing fast enough. I don't think a break would give you this agility.
Why the AI "engineering expert"? Seems to take some credibility away from what otherwise could be an interesting and informative read.
barbegal 2 hours ago [-]
Yeah I couldn't get past so many issues in the AI generated illustrations. Not useful at all when they are completely wrong.
Tanxsinxlnx 58 minutes ago [-]
right
moffkalast 58 minutes ago [-]
Even the video is generated. The whole thing is just slop upon slop, I'm amazed that it got to the top of the front page here. I suppose it's a genuinely impressive amount of fakery all integrated together.
elil17 2 hours ago [-]
I simply do not understand why you would ever prefer a fully humanoid robot as opposed to a humanoid torso on some other locomotion system.
v9v 37 minutes ago [-]
There are a few of these being sold as products: AGIBOT has some models like that (eg https://www.agibot.com/products/A2_W). One argument that could be made for legged robots is that these wheeled ones can only work in wheelchair-accessible spaces. Legged robots can also balance themselves dynamically: a wheeled robot may tip over if anything violates its static balance, eg. carrying a load high up and going through a steep incline, though I guess having the torso be tiltable as in https://www.agibot.com/products/G2 addresses that.
Legged robots overall have more implementation complexity, spend energy just to idle standing up, but can go over much more varied terrain provided the controller is good enough. There are ways to adapt wheeled bases to different terrains (eg. larger wheels, whegs, RHex, rocker-bogies) but we know how to use legs to locomote over many terrains from personal experience, while the perfect wheeled/non-legged locomotion system perhaps remains to be designed.
There's also the way robotics is going toward data-driven methods, which in some forms (ie. imitation learning) require human teleoperation data. Here having the robot mimic the human form makes the mapping from human joints to robot joints easier (compared to other morphologies where you'd need to figure out how to best approximate a human motion with the joints/joint limits your robot has, though this is not impossible).
zarzavat 1 hours ago [-]
Presumably for outdoors or home deployment. The world is designed for bipedal locomotion, and human bipedal locomotion is designed for the world.
But yes, for a factory or commercial environment it doesn't make too much sense. It would be cheaper to adapt the environment, and many commercial environments are already designed to be accessible for wheelchair users anyway.
> Besides that, our entire technology is based on the human form. An automobile, for instance, has its controls so made as to be grasped and manipulated most easily by human hands and feet of a certain size and shape, attached to the body by limbs of a certain length and joints of a certain type. Even such simple objects as chairs and tables or knives and forks are designed to meet the requirements of human measurements and manner of working. It is easier to have robots imitate the human shape than to redesign radically the very philosophy of our tools.
bloak 55 minutes ago [-]
It seems that he wrote that in a book published in 1953, but it's weird, I find, that he was imagining a robot driving a car. I would have thought he would have imagined that cars would become robots well before there would be humanoid robots wanting to drive them. So by the time you have a humanoid robot wanting to drive a car it's just one robot talking to another robot, electronically. And knives and forks are for eating, which humanoid robots presumably don't need to do, and is it likely that humanoid robots will need chairs in the same way that humans do? Altogether, a bad set of examples, I find. Perhaps the thesis would be more convincing with some better examples.
elil17 1 hours ago [-]
Right, but:
1. Asimov wrote that because he needed robots to be indistinguishable from humans for plot reasons.
2. We do 99% of our tool use with our arms and hands. We are already very good at building robot arms. We are getting better at robot hands. We can build robot legs, but they're very expensive and they pose a major safety risk for the robot itself and surrounding humans (because the robot can fall if there is a failure). For most applications, why not just put biomimetic hands and arms on a rolling base?
Of course, all this humanoid robotics research is still useful because if you can build a fully humanoid robot you can trivially build a torso-on-rolling-base robot. I sort of suspect that most of the humanoid robotics companies already know that the vast majority of their sales will be in that category.
DoctorDabadedoo 27 minutes ago [-]
It's 100% a HMI and moving costs to the other end of supply chain.
We can have optimized automation in warehouses/logistics, but if you talk to any site manager you learn very quickly that no one wants any downtime or impact to their operation to introduce new machinery or optimize traffic, etc. If it is not built with that from the start it's very hard to introduce it later on unless there is a very clear deployment path and cost structure.
And boy, robotics currently has any of those today. Sure, move those billions in to R&D. Time will tell.
rob74 1 hours ago [-]
You can still have a humanoid robot that looks very different from an actual human (and most robots from Asimov's novels were of that kind, although one of the main characters wasn't - https://en.wikipedia.org/wiki/R._Daneel_Olivaw).
Ok, so maybe a robot with wheels could solve most tasks, but it would still be severely limited: couldn't climb stairs (which would make it unsuitable as a domestic robot in a house or multi-storey flat), couldn't drive a car, truck or any other vehicle designed for humans etc.
One of the codenames for Segway was "Ginger", a reference to Ginger Rogers, because the codename for iBOT was "Fred Upstairs" (a pun on Fred Astaire).
po1nt 53 minutes ago [-]
Why not make a robotic chair? Why not build our environment out of specialized robots instead of using a hammer for everything?
rob74 32 minutes ago [-]
Sure, there are already robot vacuum cleaners, but I somehow fail to imagine how (a) specialized robot(s) that can e.g. sort your used laundry, wash it, dry it, iron it (if necessary), fold it and put it back into the cupboard would look like?
gpugreg 52 minutes ago [-]
This is AI slop and the article contains some of the worst illustrations I have ever seen. Most do not make any sense mechanically. Here are the worst ones:
- The "orbiting threaded rollers" in figure 6 are not meshing with anything (not that they could, since they are orientated in the wrong direction).
- The ball of the ball screw in figure 7 deforms the screw and the roller screw "meshes" with a flat surface.
- The guy on the pogo stick in figure 14 is jumping himself rather than putting his feet on the stands of the pogo stick.
- In figure 16, a key penetrates the elastomer skin of the optical tactile sensor, destroying it.
- The gears in figure 20 touch perpendicularly.
ofrzeta 47 minutes ago [-]
Is it? Now I feel bad for having posted it. I mean, I know some stuff but not enough to judge over all the content in this article. It's unfortunate but from glancing over I thought it was a comprehensive and useful resource. I guess I will just give up on the Internet or something like that.
sailingparrot 42 minutes ago [-]
« Rotary Actuators (The "Reflected Inertia" Trap) », « Quasi-Direct Drive (QDD) — The "Cheetah" Approach «
The pattern ‘something — The « metaphor » <qualifier> ‘ screams Gemini. Gemini seem completely unable to generate a section title that doesn’t follow this annoying pattern.
ofrzeta 39 minutes ago [-]
> - The ball of the ball screw in figure 7 deforms the screw and the roller screw "meshes" with a flat surface.
Really, it is hilarious. This will teach me a lesson or two.
BoppreH 44 minutes ago [-]
- Figure 3 has "elboly actuators" for the elbow joints (zero hits on Google for the term).
Could it be just the illustrations? I'm not knowledgeable enough to judge the text contents.
ofrzeta 41 minutes ago [-]
Now that you mention it ... apart from the typo the style of the illustration has all marks of AI.
russdill 42 minutes ago [-]
The YouTube channel linked is more of the same. Just the absolute worst slop
Loic 32 minutes ago [-]
Asking: As gpugreg remarked[0], this is AI slop to the point that it is impossible to trust anything from this article/blog post. As such, I flagged the submission.
- I wonder, is it possible to give a reason to the flag?
- Is flagging the submission without comments the right way to go?
For me, it is important that slowly but surely it goes through that AI slop is not what is accepted here on HN. Yes to have whatever LLM helping with grammar, spelling, etc. but the content should not be the output of a one shot "write me a blog post about humanoid robot actuators" prompt.
I cannot un-see these left border hints, it's driving me crazy.
modeless 3 hours ago [-]
AI was clearly heavily used in the making of this article, and I almost dismissed it as slop. But after reading it I think there's enough correct information here for it to be useful as a general overview of the problems in the space.
raphman 1 hours ago [-]
I believe that bad/wrong explanations are actually much worse than no explanations.
Many figures seem to be either missing key information (e.g. Fig. 5: the elliptical deformation is not shown - a human artist would have created a very different figure to explain the concept) or plain wrong (Fig. 6: the threaded rollers have the wrong orientation, Fig. 7: the ball is much too large for the bearing and the whole figure seems nonsensical at first glance).
And if the author did not spot these obvious problems with the figures, they either have no clue, accept sloppy work, or didn't even read the article they generated. That article is not really good advertising for the company's products.
(That the link behind the author's name leads to their Wikipedia article which seems to be a revised copy of the CV on their website is interesting, too.)
ramon156 1 hours ago [-]
They should've left out figure 6. it adds very little and the screws are wrong.
itrunsdoomguy 46 minutes ago [-]
Do they run Doom?
spwa4 14 minutes ago [-]
TLDR: we don't have the actuators required to make humanoid locomotion work reliably.
Also: something every human actually kind of knows. You need to take impacts on muscles, not on mechanical connections. Even if we had the actuators required, you also need perfect control. The only way actuators can work this well is if they properly predict the impacts so that the power of the motor ("the magnetic field") can absorb nearly all the impact. If you try to take the impacts even on human bones (that are very solid and self-repairing) they will break surprisingly quickly.
ReptileMan 2 hours ago [-]
Except we don't need 100% bipedal robots. Wheels are perfectly ok for majority of city work and factory floor.
Put the robot on rollerskates break the wheels for the occasional stair.
Miles_Stone 3 hours ago [-]
[flagged]
Rendered at 08:53:33 GMT+0000 (Coordinated Universal Time) with Vercel.
I spent some time on legged locomotion back in the 1990s. It was clear then that you wanted torque control, and I did some work on the theory for that, trying to solve it from first principles, not machine learning. Got some nice theory and a patent out. But the parts just weren't there to build such things. As the article points out, the key to this is motor back-drivability. The final drive has to survive shock loads, and it has to dump forces into the motor, where the magnetic fields can take it. As I've quoted before, "you cannot strip the teeth of a magnetic field", a comment from early General Electric locomotive sales. (Locomotives are Diesel-electric, not Diesel with a clutch and shifting gearbox, because the clutch required is huge. Yes, it's been tried.) That's something few areas of engineering cared about, with the exception of aircraft flight control systems with mechanical backup.
Pneumatic actuators looked promising, but proportional dynamic valves were big, heavy, and about $1000 each. Linear motors (not ball screws) looked like the coming thing back then, as 10:1 power/weight ratio had been achieved. But that technology never got much further, and Aura, the biggest player, collapsed in a financial scandal. Series elastic actuators were (and still are) a race between the spring compressing and the ball screw motor starting up. Hydraulics were too clunky; Boston Dynamics built a 400 pound mule, but the Diesel power pack never worked. Direct drive pancake motors were used by some SCARA industrial robots, but those were too big for leg joints. I thought someone would crack the direct drive problem eventually, but nobody ever did. We're still stuck with some gear reduction.
Some of the exotic ideas for muscles mentioned in this article go back that far. The McKinney muscle is old, and not too useful. There was some interest in electrorheological fluids, fluids whose mechanical properties change when an electric field is applied. That didn't become useful either. Shape-memory alloys were a dead end; liquid cooling can overcome the slowness problem, but not the inefficiency problem. Everybody went back to good old electric motors, although they became 3-phase AC instead of DC. It helped that the drone industry made 3-phase motors and their controllers small, cheap, and powerful.
Academic robotics groups were tiny. MIT and Stanford had less than a dozen people each. Progress required hundreds of millions of dollars for all that custom engineering and R&D. The level of effort just wasn't there. Nor would throwing money at the problem prior to machine learning have led to useful products.
It's impressive what's been accomplished in the last five years. It took a lot of money.
on edit: apologies if my analogy is not the best.
it's indeed a mess.
Even if private labs have a viable platform solution, people won't care unless they can clone it for free. Not a lot of incentive for design change, but building Kryten 2X4B-523P would be hilarious. =3
From what I can understand this is the Robbie Dickson in question: https://www.huffpost.com/entry/lessons-from-a-serial-ent_b_9...
Nobody has a problem with companies using AI to edit articles, create images. But when even the writer is an AI persona, the trust factor gets destroyed.
> The "Zero RPM" Problem
> When a robot bends its knees to stand, the motor must constantly fight gravity. There is no skeletal structure to lock against. To an electric motor, holding a static load—known as stall torque—is the most punishing state possible.
Why not just add some kind of brake that can fully or partially lock the joint?
Also the brake components are never in the same plane as the drive components, so now you have additional forces to engineer for.
Opentorque actuator
https://www.gabrael.io/new-page
https://github.com/G-Levine/OpenTorque-Actuator
Legged robots overall have more implementation complexity, spend energy just to idle standing up, but can go over much more varied terrain provided the controller is good enough. There are ways to adapt wheeled bases to different terrains (eg. larger wheels, whegs, RHex, rocker-bogies) but we know how to use legs to locomote over many terrains from personal experience, while the perfect wheeled/non-legged locomotion system perhaps remains to be designed.
There's also the way robotics is going toward data-driven methods, which in some forms (ie. imitation learning) require human teleoperation data. Here having the robot mimic the human form makes the mapping from human joints to robot joints easier (compared to other morphologies where you'd need to figure out how to best approximate a human motion with the joints/joint limits your robot has, though this is not impossible).
But yes, for a factory or commercial environment it doesn't make too much sense. It would be cheaper to adapt the environment, and many commercial environments are already designed to be accessible for wheelchair users anyway.
> Besides that, our entire technology is based on the human form. An automobile, for instance, has its controls so made as to be grasped and manipulated most easily by human hands and feet of a certain size and shape, attached to the body by limbs of a certain length and joints of a certain type. Even such simple objects as chairs and tables or knives and forks are designed to meet the requirements of human measurements and manner of working. It is easier to have robots imitate the human shape than to redesign radically the very philosophy of our tools.
1. Asimov wrote that because he needed robots to be indistinguishable from humans for plot reasons.
2. We do 99% of our tool use with our arms and hands. We are already very good at building robot arms. We are getting better at robot hands. We can build robot legs, but they're very expensive and they pose a major safety risk for the robot itself and surrounding humans (because the robot can fall if there is a failure). For most applications, why not just put biomimetic hands and arms on a rolling base?
Of course, all this humanoid robotics research is still useful because if you can build a fully humanoid robot you can trivially build a torso-on-rolling-base robot. I sort of suspect that most of the humanoid robotics companies already know that the vast majority of their sales will be in that category.
We can have optimized automation in warehouses/logistics, but if you talk to any site manager you learn very quickly that no one wants any downtime or impact to their operation to introduce new machinery or optimize traffic, etc. If it is not built with that from the start it's very hard to introduce it later on unless there is a very clear deployment path and cost structure.
And boy, robotics currently has any of those today. Sure, move those billions in to R&D. Time will tell.
Ok, so maybe a robot with wheels could solve most tasks, but it would still be severely limited: couldn't climb stairs (which would make it unsuitable as a domestic robot in a house or multi-storey flat), couldn't drive a car, truck or any other vehicle designed for humans etc.
Its predecessor was a stair-climbing wheelchair: https://en.wikipedia.org/wiki/IBOT
One of the codenames for Segway was "Ginger", a reference to Ginger Rogers, because the codename for iBOT was "Fred Upstairs" (a pun on Fred Astaire).
- The "orbiting threaded rollers" in figure 6 are not meshing with anything (not that they could, since they are orientated in the wrong direction).
- The ball of the ball screw in figure 7 deforms the screw and the roller screw "meshes" with a flat surface.
- The guy on the pogo stick in figure 14 is jumping himself rather than putting his feet on the stands of the pogo stick.
- In figure 16, a key penetrates the elastomer skin of the optical tactile sensor, destroying it.
- The gears in figure 20 touch perpendicularly.
The pattern ‘something — The « metaphor » <qualifier> ‘ screams Gemini. Gemini seem completely unable to generate a section title that doesn’t follow this annoying pattern.
Really, it is hilarious. This will teach me a lesson or two.
Could it be just the illustrations? I'm not knowledgeable enough to judge the text contents.
- I wonder, is it possible to give a reason to the flag?
- Is flagging the submission without comments the right way to go?
For me, it is important that slowly but surely it goes through that AI slop is not what is accepted here on HN. Yes to have whatever LLM helping with grammar, spelling, etc. but the content should not be the output of a one shot "write me a blog post about humanoid robot actuators" prompt.
[0]: https://news.ycombinator.com/item?id=48005917
Many figures seem to be either missing key information (e.g. Fig. 5: the elliptical deformation is not shown - a human artist would have created a very different figure to explain the concept) or plain wrong (Fig. 6: the threaded rollers have the wrong orientation, Fig. 7: the ball is much too large for the bearing and the whole figure seems nonsensical at first glance).
And if the author did not spot these obvious problems with the figures, they either have no clue, accept sloppy work, or didn't even read the article they generated. That article is not really good advertising for the company's products.
(That the link behind the author's name leads to their Wikipedia article which seems to be a revised copy of the CV on their website is interesting, too.)
Also: something every human actually kind of knows. You need to take impacts on muscles, not on mechanical connections. Even if we had the actuators required, you also need perfect control. The only way actuators can work this well is if they properly predict the impacts so that the power of the motor ("the magnetic field") can absorb nearly all the impact. If you try to take the impacts even on human bones (that are very solid and self-repairing) they will break surprisingly quickly.
Put the robot on rollerskates break the wheels for the occasional stair.