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CARA – High precision robot dog using rope

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Re: CARA – High precision robot dog using rope

#111

Post by kragen »

michaelt wrote: post #106
kragen wrote: post #57

Earlier quoted context omitted.

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…

I think there are CNC machines that cost 100 times more than US$100k.

Re: CARA – High precision robot dog using rope

#112

Post by lazide »

scotty79 wrote: post #92
kragen wrote: post #59

Earlier quoted context omitted.

Land mines have been killing people by surprise for decades. Flying drones, some of them dropping land mines and others lying in wait for incoming convoys, produced 70% of the casualties on both sides in the Ukrainian invasion last year, and a few weeks ago the Ukrainians shipped some drones to near a Russian airport several thousand kilometers from Ukraine to blow up a bunch of airplanes. This betokens a future of b…

I'm more optimistic. I think filling battlefields with autonomous weapons will make humans obsolete there and reduce war causalities. Basically any attack on humans is going to be a war crime and terrorism akin to attacks on civilians russia is doing right now

That is a really weird take considering how hard Russia (and Ukraine) work to continue to kill humans in the same situation you are describing.

Re: CARA – High precision robot dog using rope

#113

Post by kragen »

scotty79 wrote: post #92
kragen wrote: post #59

Earlier quoted context omitted.

Land mines have been killing people by surprise for decades. Flying drones, some of them dropping land mines and others lying in wait for incoming convoys, produced 70% of the casualties on both sides in the Ukrainian invasion last year, and a few weeks ago the Ukrainians shipped some drones to near a Russian airport several thousand kilometers from Ukraine to blow up a bunch of airplanes. This betokens a future of b…

I'm more optimistic. I think filling battlefields with autonomous weapons will make humans obsolete there and reduce war causalities. Basically any attack on humans is going to be a war crime and terrorism akin to attacks on civilians russia is doing right now

Well, suppose you have two countries at war, say, Burnia and Hevonia. They each produce a million autonomous weapons.

Burnia sends their million autonomous weapons to kill the million people they judge are most crucial to Hevonia's war effort, prioritizing Hevonia's political leadership and military officers.

Hevonia, meanwhile, sends their million autonomous weapons to destroy Burnia's autonomous weapons, when they can find them, but not to attack any humans.

Who wins the war?

I think Burnia does, because even if Hevonia's weapons are 99% effective, Hevonia's government has still lost its top ten thousand people, including all of their military officers, while Burnia has only lost half a billion dollars. That's going to make it impossible for Hevonia to keep fighting. And I think 50% effective is more likely.

Re: CARA – High precision robot dog using rope

#114

Post by kragen »

Animats wrote: post #88
dyauspitr wrote: post #83

Earlier quoted context omitted.

How is there no backlash? I can’t imagine a rope drive without backlash.

Improved materials. Kevlar and Dyneema.[1] Dyneema is about 15x stronger than steel per unit weight. Kevlar toothed belts have been available for many years, and can be used for many of the same applications as this capstan setup. Neither material has much elasticity. The advantage over gears is that overloads are distributed over much more material. You don't snap gear teeth. This is good for leg landing shocks. [1]…

The relevant feature of Dyneema is specifically that its Young's modulus is much higher than most other organic fibers, about half that of steel, which is probably what you mean by "neither material has much elasticity".

Steel cables would work just as well if weight isn't a consideration, but I think Dyneema is likely to be more resistant to abrasion. However, heat produced by any significant dynamic friction will ruin it immediately, as I found to my sorrow. Kevlar is much more heat-resistant, and of course steel is more heat-resistant than Kevlar.

Re: CARA – High precision robot dog using rope

#115

Post by mrheosuper »

imtringued wrote: post #90
Lerc wrote: post #30

Earlier quoted context omitted.

I recently found his videos also. It's one of those things that gets my mind bubbling with ideas for things I want to make, never enough time to do them all though (and this breadboard beside me is asking for attention) It does make me wonder about the algorithm, Quite a lot of things I find on Youtube turn up on HN a week or two later. I'm not sure if this is an indicator of the effectiveness or failure of the algor…

I get absurdly niche videos with 33 views in my feed about robotics but most of them have views in the low thousands. The algorithm isn't holding you back.

i noticed recently YT has been suggesting micro-small channel(<1000 subscriber) to me, not sure if this is good thing.

Re: CARA – High precision robot dog using rope

#116

Post by kragen »

lazide wrote: post #112
scotty79 wrote: post #92

Earlier quoted context omitted.

I'm more optimistic. I think filling battlefields with autonomous weapons will make humans obsolete there and reduce war causalities. Basically any attack on humans is going to be a war crime and terrorism akin to attacks on civilians russia is doing right now

That is a really weird take considering how hard Russia (and Ukraine) work to continue to kill humans in the same situation you are describing.

Who cares if it's weird? Why are you saying "weird" as if that were a bad thing? It's just a derogatory synonym for "unusual". A take would have to be weird to be a contribution to the conversation, because if it's not weird, it's a widely held opinion we all already know, and nobody gains anything by reading it.

What matters, given that it meets the minimal bar of weirdness to be potentially worthwhile, is whether it's correct. Which depends on what future combatants will do once weaponry actually is autonomous, not what Ukraine and Russia are doing with remotely-piloted FPV drones.

Re: CARA – High precision robot dog using rope

#117

Post by froh42 »

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.

Re: CARA – High precision robot dog using rope

#118

Post by indigo945 »

froh42 wrote: post #117

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.

That's not the video's fault, but YouTube's. YouTube has started adding automatic AI voiceover translations to all videos, unless the uploader explicitly disables them for each single video. It's opt-out and the option is well-hidden, so most uploaders will not disable it.

As an end user, there's nothing you can do to prevent from seeing them. But you can change the audio track to the original while the video is playing.

Re: CARA – High precision robot dog using rope

#119

Post by regularfry »

kragen wrote: post #114
Animats wrote: post #88

Earlier quoted context omitted.

Improved materials. Kevlar and Dyneema.[1] Dyneema is about 15x stronger than steel per unit weight. Kevlar toothed belts have been available for many years, and can be used for many of the same applications as this capstan setup. Neither material has much elasticity. The advantage over gears is that overloads are distributed over much more material. You don't snap gear teeth. This is good for leg landing shocks. [1]…

The relevant feature of Dyneema is specifically that its Young's modulus is much higher than most other organic fibers, about half that of steel, which is probably what you mean by "neither material has much elasticity". Steel cables would work just as well if weight isn't a consideration, but I think Dyneema is likely to be more resistant to abrasion. However, heat produced by any significant dynamic friction will r…

Dyneema is much easier to work with, too.

I'm quite fond of bowstring as a material for this sort of thing. It usually has other fibres mixed in with it so it's a little more bouncy than raw dyneema but that's minimised if you get thread that's intended for crossbows. It's usually waxed so there's some friction to it when you're manipulating it, and it's also easy to source.

Re: CARA – High precision robot dog using rope

#120

Post by regularfry »

kragen wrote: post #111
michaelt wrote: post #106

Earlier quoted context omitted.

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…

I think there are CNC machines that cost 100 times more than US$100k.

Some products should be compared on a log scale. CNC machines are a very good example.
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