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How can this 6 axis robot have a static accuracy of 0.05 mm? (2021) [video]

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Re: How can this 6 axis robot have a static accuracy of 0.05 mm? (2021) [video]

#31

Post by toxik »

lazide wrote: post #18
imoverclocked wrote: post #15

Question for anyone who has used one of these analog measuring devices: the indicator seems to go all the way around before the camera zooms in to read the indicated value. Is this video actually showing the accuracy it is claiming?

I haven’t watched the whole video, but I’m assuming what they were showing was ‘move x from 0.00 to 10.00’ with the gauge showing the final move was to (actual) 10.05. Which with how floppy that rig is, is pretty impressive. Notably though, those gauges do need to be ‘preloaded’ (compressed into their ‘positive’ range) to be able to measure negative direction shifts, and while it looks like that was done, I can’t be…

I think it’s okay that they use the contract force to remove backlash since they are actually controlling it. In fact, if you could do that well, that’s huge!

Re: How can this 6 axis robot have a static accuracy of 0.05 mm? (2021) [video]

#32

Post by lazide »

toxik wrote: post #31
lazide wrote: post #18

Earlier quoted context omitted.

I haven’t watched the whole video, but I’m assuming what they were showing was ‘move x from 0.00 to 10.00’ with the gauge showing the final move was to (actual) 10.05. Which with how floppy that rig is, is pretty impressive. Notably though, those gauges do need to be ‘preloaded’ (compressed into their ‘positive’ range) to be able to measure negative direction shifts, and while it looks like that was done, I can’t be…

I think it’s okay that they use the contract force to remove backlash since they are actually controlling it. In fact, if you could do that well, that’s huge!

I don't think they could do that sustainably while it's actually doing 'the job' though, correct? It's pretty in the way.

Re: How can this 6 axis robot have a static accuracy of 0.05 mm? (2021) [video]

#33

Post by K0balt »

imoverclocked wrote: post #30
boeinggggg wrote: post #25

Earlier quoted context omitted.

I don't know. Maybe an expert can chime in but I think it is a hard problem because of ice etc. I think the 737Max has the problem where AoA matters more because you can get into a stall you can't get out of. Whereas maybe before on older planes you get in a stall and you nose down to reduce AoA. You don't need a sensor to know this look at altitude etc. So now you need perfect ten nines of reliability AoA sensors. T…

You never want to get into a stall in a large commercial jet. Private pilots are taught stall and maybe spin recovery techniques for small GA aircraft. ATP rated pilots are taught stall/spin avoidance. Chances are, if your AoA is anywhere near the critical AoA, a competent pilot is likely aware of it. The sensors are just another safety factor on top of that to help ensure situational awareness.

Or, in the case of the 737Max, to trigger a chain of events that proved lethal to hundreds to people. That’s the secondary use of the AOA sensor in combination with the FC software that they implemented. It would have been relatively easy to integrate the AOA input with other sensors to eliminate this problem, but it would have invited a deeper look at the hazards of their design decisions.

Bean counters bathing in blood, all the way down.

Re: How can this 6 axis robot have a static accuracy of 0.05 mm? (2021) [video]

#34

Post by foxglacier »

KeplerBoy wrote: post #11

How do 3 axis robots you can buy for 100$ (3D printers) have a static accuracy of 0.05mm? It's not control theory, but mechanics and steppers.

Yes but they're not robot arms so it's not as fascinating. The length of the arm amplifies error so if you made a "mechanics and steppers" arm with the same positional accuracy as a printer, the motors would have to be much more precise or if you geared them down, the backlash extremely low like an industrial robot arm.

Re: How can this 6 axis robot have a static accuracy of 0.05 mm? (2021) [video]

#35

Post by guenthert »

I don't see how the second sensor would improve accuracy (or rather precision). iiuc, the second sensor allows for improved speed. Backlash of the motor (and gears and linkage) could be accounted for using a PID controller, no?

Said that, I'm impressed how precise this rather flimsy looking robot actually is.

Re: How can this 6 axis robot have a static accuracy of 0.05 mm? (2021) [video]

#36

Post by maille »

KeplerBoy wrote: post #11

How do 3 axis robots you can buy for 100$ (3D printers) have a static accuracy of 0.05mm? It's not control theory, but mechanics and steppers.

I'm curious what would be the best way to replicate an x/y (optionally z) system with 0.05mm or lower accuracy? Without sacrificing speed of course.

Re: How can this 6 axis robot have a static accuracy of 0.05 mm? (2021) [video]

#37

Post by sadhorse »

maille wrote: post #36
KeplerBoy wrote: post #11

How do 3 axis robots you can buy for 100$ (3D printers) have a static accuracy of 0.05mm? It's not control theory, but mechanics and steppers.

I'm curious what would be the best way to replicate an x/y (optionally z) system with 0.05mm or lower accuracy? Without sacrificing speed of course.

Depends on how much power you need (speed times force, acceleration and deceleration...) and how much stiffness you need (can't bend?).

Also depends on how much travel you need. It is easier to get 50 micron accuracy over a total length of 100 micron compared to a total length of 1 meter.

Re: How can this 6 axis robot have a static accuracy of 0.05 mm? (2021) [video]

#38

Post by robocat »

K0balt wrote: post #33
imoverclocked wrote: post #30

Earlier quoted context omitted.

You never want to get into a stall in a large commercial jet. Private pilots are taught stall and maybe spin recovery techniques for small GA aircraft. ATP rated pilots are taught stall/spin avoidance. Chances are, if your AoA is anywhere near the critical AoA, a competent pilot is likely aware of it. The sensors are just another safety factor on top of that to help ensure situational awareness.

Or, in the case of the 737Max, to trigger a chain of events that proved lethal to hundreds to people. That’s the secondary use of the AOA sensor in combination with the FC software that they implemented. It would have been relatively easy to integrate the AOA input with other sensors to eliminate this problem, but it would have invited a deeper look at the hazards of their design decisions. Bean counters bathing in b…

> Bean counters bathing in blood, all the way down.

No resource is infinite and money is an important constraint in any engineering project. Engineering is all about making compromises. Good engineering is making the right compromises: especially when life and death decisions are being made.

Casually blaming "bean counters" is a distracting fantasy available to anyone that doesn't have to make real-world decisions. Understanding the causes of how Boeing systematically screwed up requires a bit more maturity than you appear to show. "Bean-counters" particularly comes across as childish name-calling to me, and clichés don't help either.

The fact that the MAX has been cleared to fly again shows that the design decisions were not utterly flawed.

Re: How can this 6 axis robot have a static accuracy of 0.05 mm? (2021) [video]

#39

Post by chipdart »

llm_trw wrote: post #20

If anyone wants to build this sort of thing the new Raspberry Pie Pico 2 is both orders of magnitude more capable than the chip used here and also around half the price. It's by far the best value for money for an introductory 32bit ARM/Risk embedded device right now.

> (...) the new Raspberry Pie Pico 2 is both orders of magnitude more capable than the chip used here and also around half the price.

That's cool and all but what are the tradeoffs?

Re: How can this 6 axis robot have a static accuracy of 0.05 mm? (2021) [video]

#40

Post by moffkalast »

chipdart wrote: post #39
llm_trw wrote: post #20

If anyone wants to build this sort of thing the new Raspberry Pie Pico 2 is both orders of magnitude more capable than the chip used here and also around half the price. It's by far the best value for money for an introductory 32bit ARM/Risk embedded device right now.

> (...) the new Raspberry Pie Pico 2 is both orders of magnitude more capable than the chip used here and also around half the price. That's cool and all but what are the tradeoffs?

Well it's new, it'll take a while for support to stabilize. The Pico 1 took almost a year given that the whole concept of a PIO was new, but this one should get there far sooner.
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