We can only hope the parent comment indeed knows a better source or even what he is talking about. Let give him the benefit of the doubt and assume that the shortness of his comment derives from a lack of time and not from a lack of knowledge.
Exactly this. And the incentive it creates is very perverted. It would be much easier to just tax CO2 at the source, instead of this corruption prone system of carbon credits where you need to audit thousands of places instead of only one: the oil pipe.
We enjoyed a peaceful 'air pocket' in tech, but this is over. And it makes sense. Technology is rendering regular people useless. And when they eventually get destitute they will rebel. If I were the ruling elite I too would move fast to increase my control over the masses.
It really is incredible to believe that a sports organization has the power to shutdown what is essentially a utility without any oversight. It paints a very bad image of Spain in my mind. It makes one wonder how many more absurdities happen over there.
Disclaimer: I am the ntfy maintainer. Pleasantly surprised to be mentioned, hehe.
Pushover is an amazing tool and works well. In my obviously biased opinion though, I think that ntfy has a ton more features than Pushover and is fully open source. You can self host all aspects of it or you can use the hosted version on ntfy.sh for free, without signups, or pay for higher limits.
I love hearing that. Anything worth sharing? I love hearing how people use it. My favorite one is the guy protecting his apple tree from thieves by adding a camera and motion sensor and then sending himself a notification with the picture to catch the apple thief.
I have a few things. One is home security, I get basic notifications when something is in the driveway. I'm working on getting Frigate running to hopefully give me the names or license plates of people when they arrive.
I also have one tied to a manufacturing database at my company. When a batch of products rolls off the line I get an updated count of units made. Kind of a way to know production systems are running and there are no problems at the work cells.
I also made a rickety-ass system that scrapes the local commuter rail API and fires off a notification when one of my trains is late or cancelled. That's been pretty helpful. The rail company has a Twitter account, but I don't go there anymore. So I rolled my own.
I don't know, I've never used pushover. A quick look at their home page doesn't seem to indicate the option of self hosting on a VPS, so that precludes it for me. Otherwise from the code samples provided, it looks quite similar.
AI research is like the topic of sex during adolescence: of everyone say they are doing it, few are; and the few that are in fact doing it are probably doing it wrong.
Well, it probably wasn't that much effort. When you're 3D printing you're going to end up printing everything 2-3 times anyway, so why not dial in the ratio while you're at it?
And you can't really declare your design is "high precision" and present yourself as someone others should take transmission design advice from if you aimed for a gear ratio of 8 and achieved "somewhere around 7.9 to 8.2"
It probably doesn't matter so much whether it's 7.913 or 8.186, but it would be important to know the exact value for kinematics. One way to do that is to build an object very accurately, the other is to build inaccurately and then measure the result after the fact.
It's also interesting because competing actuators with strain-wave, cycloidal, or planetary gearboxes will state exactly what the ratio is. The actual gear teeth may not be spaced out perfectly around the circumference, but the number of teeth is an integer with an infinite number of zeros.
Yeah, I think one of the nice things about making it a "clean" number (either an integer or a rational with a small integer denominator) is that you can easily validate it without needing high-precision measurement equipment: put a mark on both gears (maybe even embedded in the 3D print), line up the marks, rotate the large gear 1 full rotation, and count the number of rotations the smaller gear makes. Check to see if the marks line up perfectly after those rotations.
It could though. I don’t think the thought has occurred to him yet. He could make the stack twice as high and go around twice as far. If you moved the worm gear you could go farther, but I don’t know how he would do that with his drive.
He could also go with narrower rope, and spread the load over more windings, which would give him more throw.
What are the loads on a drive in this use case? 35lbs robot bouncing on one foot would be 350lbs-ish of dynamic load? That can be handled with 2mm Dyneema.
At 2:02 he shows a working model with a smaller diameter cord than his earlier ones. Looked like he’s already using 1/8 or smaller.
Notice that the fastener bearing the weight of the cord is wrapped around two bends. If I recall my physics properly, each of those direction changes behaves like a pulley, halving the strain on the bight (dyneema is difficult to fasten though. Slippery bugger.)
> Also, I wonder how resistant this mechanism is to wear and fatigue.
He actually discussed this in an earlier video for his initial tests on the capstan drive. He ended up testing the rope he used for around 358 hours (two weeks) on continuous use in the drive itself with very low backlash
Because when a real engineer puts 2 and 2 in and gets 3.8 out, it vexes them and they want to at least know why they can’t get 4. He’s trying to make a machine that does what he told it to do, so that he understands what is actually happening.
I think it's about kinematics, the more precise your gears the better the model fits the real world.
That's why pro crews don't use gears and ropes. At high impulses deformations and elasticity throw the kinematics off what's actually happening. Modeling the deformations and the elasticity is a computational no no. Instead what you see is the motors right on the joints.
At least that was the case last time I had a look at robotics.
> That's why pro crews don't use gears and ropes. [...] Instead what you see is the motors right on the joints.
The answer here, as with so many things in robotics, is: It Depends.
UR10e robot arm that can lift a 4kg object with a reach of 1m and has sub-1mm repeatability? Strain wave gears in the base and shoulder joints, 100:1 ratio.
MIT Mini Cheetah robot dog that can do backflips? 6:1 planetary gearbox.
Shadow Hand with 20 degrees of freedom? Tendon driven, with the 20 motors in the forearm to keep the fingers slim.
Little dinky Huggingface SO-101? Servo motors, integrating 1:345 gearing with a series of 6 tiny brass gears.
Mid-price CNC milling machine, if you call that a robot? Really long ballscrews, driven by stepper motors.
Surely you mean driven by closed-loop servos with encoders, don't you? Jacques Mattheij wrote a long post about how he ended up having to replace all the CNC machines he sold that used stepper motors because he didn't know any better at the time, and brushless motors are a lot faster and more powerful as well as not losing steps.
I guess "mid price" isn't the most helpful term when machines vary from $100 to $100,000 huh?
I think the X-Carve 3-axis wood carver uses stepper motors with belts of all things. The Shapeoko Pro is leadscrews and stepper motors. Wazers, I believe, are belt-and-servo driven. And a lot of 'CNC conversion kits' you can order online use stepper motors. Plus of course laser cutters have really low torque requirements, so they've got a lot of design freedom.
Arguably those are "cheap" rather than "mid price" it just felt weird to declare a $4000 machine to be "cheap"
Actually, it was the Shapeoko 1 which introduces the idea of belts (MXL), then switching to Gates GT2 belts with the SO2 (ob. discl., I got a free machine for doing the instructions, see Github). Since it was opensource, the X-Carve was forked from the SO2, though the X-Carve Pro was a completely new design.
Note that belts were continued through the Shapeoko 3 (I got a machine as a "thank you"), though the Z-axis got a leadscrew in the Z-Plus upgrade, then the Pro (since, I got a job with the company and got an XXL as part of my employment), then the 4 (the original Pro is referred to as a 4 Pro sometimes), and it is only with the 5 pro that ball screws were switched to for all axes (and I now have a 5 Pro).
For an example of what a belt-drive CNC can do see:
On the other hand, a 100:1 gearbox gives you much-needed torque if you're lifting a load at the end of a long arm, it makes your encoder 100x more precise (in terms of repeatability) and it makes your motor brake 100x stronger.
Back-drivability is the enemy of precision, so many robotic applications can do without it.
Almost all modern servo driven units I've seen prefer to allow some compliance in the end effector. The UR5 and UR10 series for example can use force limiting control loops, and are safer to use around people.
The old "fast, cheap, or good... choose any two joke is mostly still true. =3
The UR10 uses 100:1 strain wave gearing in the base and shoulder joints.
You’re right that it has a freedrive mode, and force control modes. But it’s a rigid, low-backlash robot with the compliance achieved in software afterwards.
Expensive, naturally, but none of the problems that come with things like series elastic actuators.
> At high impulses deformations and elasticity throw the kinematics
Sure. Yet evolution has achieved astonishing kinematics with all manner of deformation and elasticity inherent to the materials, and also constantly changing physical properties, using low resolution data. We cannot build permanently lash free mechanical devices at reasonable cost and reasonable size/weight. Eventually, the answer must be pervasive real-time compensation throughout the kinematic model.
> Modeling the deformations and the elasticity is a computational no no.
Why? Nervous systems do this. That's why you can change your shoes and still walk upright.
In the video he mentions how the specific type of Dyneema cord he's using is well-suited for the application (compared to other kinds of rope/cord). It's particularly strong, light, and inelastic; a lot of climbing equipment uses a version of it for similar reasons.
> Modeling the deformations and the elasticity is a computational no no. Instead what you see is the motors right on the joints.
That sounds like “It’s not wrong, we just don’t do it”. There are some amazing examples of imprecise drive systems compensated for by excellent control systems all over the world, for millions of years.
Yet for some reason unknown to me, people get annoyed when you tell them „let us meet at 13:37. that is no more accurate than let us meet at 14:00 hours”
I don't think the number of the gear ratio really matters, what matters is that you know what it actually is (since every IK calc depends on said ratio); 8:1 is probably arbitrary and/or looks nice & might simplify some stuff.
It might be a lot easier to check the ratio "by hand" (by counting rotations etc) if it's numerically simple. (IIRC in some earlier videos he noticed that the pulley size ratio wasn't producing the expected movement ratio, because they were built as an obvious 8:1 or 10:1 or something, and didn't match - which led to him figuring out the subtleties of the design - I can easily imagine wanting to preserve that aspect just for debugging, at that point, even if you now have correct math.)
I live in a seismically active (and poor) area. Dunk on Google all you want, they're the only organization who provide earthquake alerts in my area. The government has better things to spend money on (like pervasive corruption), but Google usually sends a notification 30-60 seconds before a perceptible earthquake happens.
Note that they're also one of the only ones who can unilaterally choose to preinstall this on a majority of devices around the world. Of course I agree that it's good that they do it, for free and all, but to put it in perspective it's either each government for themselves or one of the two global superpowers that have devices with accelerometers and constant internet connectivity on every square kilometer of this oblate spheroid
Google (and Apple) has been partnering with ShakeAlert from USGS for quake reporting on west coast of US. But that takes network of seismometers and detection system.
I could see smartphone seismometers being useful for areas that don't have all that. OTOH, if phones are useful seismometers, it should be possible to make cheap, dedicated ones.
The closest one (that I know of) is approximately 1000 km away, and it does provide data about earthquakes, but only after the fact. They already have some information sharing, because I usually look up the info on usgs.gov, but almost certainly not in real time.
We’ve had this Google service in El Salvador for a while, and it’s really cool. The first time we received an earthquake alarm we felt like we were living in Japan. I never thought we would have Japanese-style earthquake alerts here.
iPhone users were a bit annoyed though, because it only worked on Android phones.
Google alone tackling this problem for 10 years and then killing it is still better than no one solving this problem and no one getting 10 years of free earthquake alerts.
big companies doing stuff for free can kill industries.
10 years is enough the ensure that any professional and company trying to make a living from earthquake early detection systems is working on something different.
yeah, someone will pop up after they inevitably kill it, but this stuff can end up delaying progress.
Case in point: Google providing Android for free killed Windows Phone, Symbian, PalmOS, Blackberry, and several other attempts to create a mobile device OS
Which was among the reasons that Google did that, not that the company would say so.
Microsoft ran Windows Phone into the ground. I could rant, but WP7 was interesting, WP7.5 was usable, WP8 and WP8.1 were pretty good, and then WM10 was very late and pretty meh. Had WM10 shown up on time and with quality, we would have a different discussion. Lots of OEMs were making phones for WP8, not many for WM10.
Symbian had flirted with Open Source, but IMHO, Nokia's fight with US carriers over shipping a SIP client and the resulting disappearance from the US market of most Nokia phones doomed Symbian... Tech journalism is dominated by US outlets and nobody reported on Symbian phones because they weren't there.
I assume you mean Palm's WebOS, cause PalmOS was pretty stylus driven and ux expectations had moved on. WebOS was neat, but Palm didn't have the corporate resources to support it.
Blackberry certainly had time and resources to compete. BB10 was supposed to be quite good, but maybe a little late.
All of these had what I like to call early mover disadvantage. Being first or at least early to a market makes it hard to adapt when the market changes. Coming in ten years late to smartphones was great for Apple and Google.
Local governments are unable to do it right because, well, they are bureaucrats who cant differentiate the left hand from their right hand. Governments IT systems are eternal money sink holes only producing power points and weekly status reports to be forever forgotten.
I assume you’ve never had the delightful experience of relying on a product Google built or acquired then let decay or killed outright because it doesn’t contribute to ad revenue and the people who cared leveraged it in their promo packet to go elsewhere.
No business has the obligation to keep running what you find useful. If it was that useful, someone else will make it.
If no one is doing it or well, I see no reason to just complain and offer no solution. If there are other solutions and Google is going to hurt or destroy "competition", that's what should be discussed.
You’re allowed to just say I’m right. When Google puts enormous amounts of resources into something like Google Home, then acquires Nest, haphazardly merges the two ecosystems while co-opting the Nest brand for unrelated products, then effectively abandons it except for the occasional update that breaks prior functionality? Sure, no obligation. But I’m not being some sort of whiny brat by pointing out that your experience with Google is driven by what will eventually become forced updates meant to drive you away from a product so they can kill it, because the internal culture/incentives promote launching and not maintaining or improving.
Someone else won't make it because they already have this for free. Well for this particular case, I think having Google product might just be better than none. But for some more critical things like typhoon warning, when people actually make decision based on data from the system, relying on a product that might get killed 5, 10 years later is worse.
If your infra is critical enough, they should nationalized, publicly owned.
> Always curious why people comment like this when they have a choice to, you know, not do it
Not OP, but it's still an important consideration - one can be both glad Google is working on this, but also cautiously optimistic given Google's history. IMO it's right to be wary of private entities taking care of what should effectively be a public service.
Did you mean cautiously pessimistic? Or maybe that's my bias from reading HN threads where this is a reliable theme in Google product threads, as well as seeing the list of killed products, while not seeing a list of kept-alive products
