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Low Cost Robot Arm

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Re: Low Cost Robot Arm

#181

Post by samatman »

sebastiennight wrote: post #172
MaxikCZ wrote: post #17

I want the arm to wander around my house, pick up articles of loose clothing and put them into washing machine. Then pull them out and spread them on a drying hanger. How far away from that are we?

Let's look at the economics. In the US or Western Europe, a human worker would cost you about $12-$15 per hour (depending on the actual city and whether they're paying their taxes). You're looking at roughly 4 hours of work per 100 square meters (the average housing size[1]) per week to get the listed activities done, plus some general cleaning. So let's call it $60 per week or $3,000 per year. If we estimate the ave…

It's unreasonable to assume that reduced demand for home cleaning would translate one-for-one into unemployment and welfare. The bottom of the labor market doesn't work that way at all.

Re: Low Cost Robot Arm

#182

Post by devsda »

alex_suzuki wrote: post #68
devsda wrote: post #63

Earlier quoted context omitted.

Unless it has to do something with the print quality itself, can't this be achieved using a stationary phone with its camera towards a monitor displaying 3D transformed barcode images ?

Yes, possibly. But reading from the screen is quite different from reading actual barcode prints, for instance you have to deal with Moirè patterns and such. And frankly it was just a good excuse to buy an arm. Sue me! ;-)

> for instance you have to deal with Moirè patterns and such

My understanding is e-ink displays will not be suceptible to that.

I might just have given you an excuse to buy a large e-ink display/monitor :)

Re: Low Cost Robot Arm

#183

Post by brcmthrowaway »

michaelt wrote: post #95
brcmthrowaway wrote: post #35

Earlier quoted context omitted.

Are the servos better than SG90?

They're "smart" which means you can form a serial bus of them, query individual motors' encoder positions and motor temperatures and whatnot, adjust the PID parameters yourself, and so on. You can also daisy-chain them together, which might reduce your cable routing problems. Downside is when they break, you're out $50 or more - and you're going to break at least one. And the manufacturer wants you to operate them at…

Wish there was something inbetween that and SG90!

Re: Low Cost Robot Arm

#185

Post by iiJDSii »

robmurrer wrote: post #126

obligatory shout out to Annin Robotics AR4. Here is my build: https://commandpattern.org/2023/03/19/ar4-robotic-arm-build/ $2K USD. 2kg payload. millimeter repeatability (if you build it well :)

Nice build! I always wanted one of those AR robot arms but I'd rather buy it off-the-shelf than assemble from scratch. I don't think anyone sells them pre-built though. This type of 'high level hobbyist robotics' is in a bit of business dead-zone unfortunately, as it's some combination of too small a market and not enough use cases to justify having a company around. Or maybe there's potential there but no one's thought of it yet.

Btw I bet your arm's movement smoothness can be improved with some different deceleration rates. It was really fun watching it sort those beans!

My research goal with one of these 'good enough' 1mm repeatability robots would be vision-guided adaptive control to complete tasks after seeing examples of them done via human manual control. Would be a really interesting ML/AI problem. Just need a reasonable hardware platform to get started. Right now I'm leaning more towards simple/smaller servo motors like in the OP of this post (plus there's the cost/time trade-off).

Re: Low Cost Robot Arm

#186

Post by iiJDSii »

xchip wrote: post #112

Please stop gluing 3 servos together and claiming you built a robot :D (servos motion is quite jerky, that is why they don't have a video showing off this "robot" operating)

As someone a lot deeper into robotics I totally get this sentiment... But I also think it's good to encourage people to share the basics, look how many newcomers in this thread find it interesting and may explore it further.

I wonder how smooth one could make a cheap servo-based robot arm operate with decent control algorithms.

Re: Low Cost Robot Arm

#187

Post by Climato »

mtreis86 wrote: post #134

I started working on a similarly sized arm. I've got a use-case, long time friends with a glass blower. I was thinking of using it to make faceted glass pendants. They've got a faceting machine but it is manually operated. The hard part is repeatability. You need tight tolerances and each joint in the arm adds inaccuracy the further you get from the base. If the base has 1mm of wiggle, the 20cm arm has 4mm wiggle at…

I think about this regularly just don't have the time to pursue it:

Couldn't you build your arm in Nvidia Omniverse by also adding feedback like a cheap hig resolution distance or angle detector and train an ml model to compensate it?

Re: Low Cost Robot Arm

#188

Post by jodrellblank »

sebastiennight wrote: post #165
jodrellblank wrote: post #162

Earlier quoted context omitted.

> " Arm wrestling a toddler " Like arm wrestling a brick wall; if you can push it over then you win, if you can't push it over then you lose - either way there's not much fun in it. And if it can beat the toddler it risks injuring them because neither of them really understand what's happening and what the risks are. The arm can't stop if the toddler says 'ow'. > " Handwriting notes for small jewelry brand? " Can be…

I like how this comment is clear, comprehensive, full of common sense, AND very likely to be completely outdated within a few generations (5 years?) of robotics + AI progress. I would also not discount how easy it is to sell people on additional cameras in their homes (including the bathroom) for the sake of convenience.

State of the Art public robot arms include Boston Dynamics' Stretch[1]. It's not for sale to the public, the price isn't public, it's got 18 suckers on a flat tray and runs on a wheeled base and looks like the size of an armchair. Boston Dynamics' Spot the walking dog robot was launched in 2020 for $75k and was explicitly not safe for use in the home or around children.

Do you genuinely think they will improve to the point of having finger style grippers, dexterity and adaptability to grind coffee, mix drinks and pick towels, and be on sale to the public, safe for use in the home, for $250 (or $2500) by Jan 1st 2030? I would be very surprised.

(Can you get a robot arm today, for any price, to help a quadraplegic open their mail, bring a drink with a straw in it to their mouth, lift them into a sitting position, hold a book in front of them and turn the pages, or ... do anything helpful? I'm not aware of any, but haven't been looking specifically).

Yes you could probably build a robot today which hands you a towel from a pile, reliably and swiftly, or selects the bottles of alcohol and opens them and pours and mixes a drink - in a carefully controlled and lit environment where none of the lids or corks are stuck and the glasses are all a similar shape and size and nobody is allowed to be near it - I don't say it's impossible with today's tech, but it would cost a lot more than $250. A hundred or a hundred thousand times more, while being far far more limited than a human.

[1] https://arstechnica.com/gadgets/2022/04/boston-dynamics-stre...

Re: Low Cost Robot Arm

#189

Post by polygamous_bat »

idiotsecant wrote: post #161
leoedin wrote: post #154

Earlier quoted context omitted.

I worked for a startup developing robot arms for a while. What we found was that giving someone a robot arm - even one with reasonable APIs and no cost to them - didn't really help because the hard part is making useful automations. Mostly people spent a few hours playing with the arm and then put it on a shelf. Every use case is completely different and is a lot of work. Even when you get something working, accident…

Yep. Interestingly, there has been a lot of recent work on models like RT-2 that might be capable of automating this for simple tasks. We might be at the point soon where that startup would have been viable!

AFAIK RT-2 doesn’t quite work outside of Googles micro-kitchen, where they collected about a 1000 hours of data.

Re: Low Cost Robot Arm

#190

Post by Gracana »

boesboes wrote: post #163
mtreis86 wrote: post #134

I started working on a similarly sized arm. I've got a use-case, long time friends with a glass blower. I was thinking of using it to make faceted glass pendants. They've got a faceting machine but it is manually operated. The hard part is repeatability. You need tight tolerances and each joint in the arm adds inaccuracy the further you get from the base. If the base has 1mm of wiggle, the 20cm arm has 4mm wiggle at…

Have you considered using belts and sprockets? They seem effective in 3d printers and pretty cheap

Belts introduce elasticity that can be very difficult to deal with.
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