EEVblog #586 - Open Source Hardware uARM 4-Axis Desktop Robotic Arm Kickstarter

[EEVblog]

Dave looks at the open source hardware UFactory uARM 4-axis desktop robotic arm kit project available on kickstarter:
https://www.kickstarter.com/projects/ufactory/uarm-put-a-miniature-industrial-robot-arm-on-your
http://www.ufactory.cc/
This is the first unit produced, and comes with the suction cup head and Arduino Uno board and shield controller.

[NiHaoMike]

A good use might be mass importing CDs or other disks onto a PC. Or conversely, automating a low volume "production" of CDs and such, probably most useful for independent artists.

[Zad]

Sorry Dave, I think being a Kickstarter backer on this item has got in the way of your objective judgement. The only value I can see is in it being a construction kit, not as a built arm.

[pickle9000]

Could you not rig it up as a simple camera rig?

Daves quadcopter probably has outputs that could connect to the servos directly. Could be a fun experiment.

You could also connect it up to to this with practically no effort.

http://www.paintballsentrygun.com/

How about Daves Robot sidekick.

It looks like a really fun toy.

[hikariuk]

I find myself a little underwhelmed.  Also missing playing with real ones.

[GiskardReventlov]

Here's my proposal, you use this robotic arm to test out the cat ratings for the multimeters. The robotic arm will do the plug in for each cat rating stated for each meter.  It needs a good name too. I propose "Electrocutioner".

If the meter dies we'll probably know it by watching but in any case the Electrocutioner will need to be programmed to give a "Thumbs Up" or a "Thumbs Down".

I also propose that a nice cloth cover be made for the Electroctioner so you can unveil it each time. It will look like an executioner's hood but maybe with a electric bolt on it.

...Dave's reviewed all other aspects to be reviewed and then he says:
"And now it's time .... for ..... the .... (with his hand on the shroud) .... Electrocutioner .... (off comes the shroud and a crack of lightning dubbed in)

[electronics man]

just seems like a gimmick.

[robrenz]

I'm sure if you replace all the pivot joints with proper bearings with proper fitting axis rods through the bearings you could eliminate most of the backlash/slop you have there. Then all you'd need to sort is the servo slop.

That is only one of the many weak points of its design. There is a reason real robots are not made from acrylic.

[pickle9000]

Other uses

- Multimeter shootout, have it knock meters off the bench. Sagan can push the button.
- Mount a hammer on it and have smash something. A bad component from a troubleshooting vid.
- Mix up some pudding.
- Robot arm multimeter bowling.
 

[EEVblog]

Sorry Dave, I think being a Kickstarter backer on this item has got in the way of your objective judgement. The only value I can see is in it being a construction kit, not as a built arm.

I said it's a toy, that's all it is. If you want a toy OSHW robot arm to play with I think it's perfectly fine.

[EEVblog]

Here's my proposal, you use this robotic arm to test out the cat ratings for the multimeters. The robotic arm will do the plug in for each cat rating stated for each meter.

I doubt it would have the strength to plug in banana plugs.

[GiskardReventlov]

I doubt it would have the strength to plug in banana plugs.

Maybe a low-force switch? I looked on digi-key, wow, for a 1000V it's $$$.

[kizzap]

Dave: If you removed the suction head, and possibly screwed it down to a bench somehow, would it be able to support the weight of a small webcam? Let users on the internet control it and look around the lab.

[mdszy]

Dave: If you removed the suction head, and possibly screwed it down to a bench somehow, would it be able to support the weight of a small webcam? Let users on the internet control it and look around the lab.

Twitch Plays Dave's Lab?

[EEVblog]

Dave: If you removed the suction head, and possibly screwed it down to a bench somehow, would it be able to support the weight of a small webcam? Let users on the internet control it and look around the lab.

I have a webcam that pans/tilts already, so no point.

[pickle9000]

Dave, by chance have you ever owned an Armatron?

I had both.

[indigoid]

Dave,

Since you waffled endlessly about the serial commands being undocumented...

This would be a great opportunity to do a video on a practical application of UART functionality of the Bus Pirate - namely sniffing all the serial chatter. Connect the UART pins on the Bus Pirate to pins 0 and 1 on the Arduino in the robot.

I used mine similarly to troubleshoot a AVR-based MIDI controller I was building recently. Bloody excellent little tool, the Bus Pirate. It's not particularly brilliant at any one thing, but it has so many applications where it is often "good enough" that for $30 it's a no-brainer.

[EEVblog]

Since you waffled endlessly about the serial commands being undocumented...
This would be a great opportunity to do a video on a practical application of UART functionality of the Bus Pirate

No point, they'll probably release it in few days when the campaign ends.

[BMac]

Dave, Had to laugh I've used hundreds of the Fanuc 410iB, Check this out.

http://pdf.directindustry.com/pdf/fanuc-europe-corporation/m-410ib/32007-381949.html

BMac

[Smokey]

That does kind of look like it. 

http://www.fanucrobotics.com/cmsmedia/datasheets/M-410iB%20Series_15.pdf

[BMac]

Yeah thats the old 410 with the big balancer on the side the new ones dont have that.
BMac

[ndim]

The obvious idea:

• remove suction head
• add uCurrent test jig
• put uCurrent panel to test under it

The banana plugs might just be self centering enough for the uArm tolerances to not matter.

[NiHaoMike]

The obvious idea:

• remove suction head
• add uCurrent test jig
• put uCurrent panel to test under it

The banana plugs might just be self centering enough for the uArm tolerances to not matter.

That won't be much (if at all) quicker than just manually testing. What might work is if it could pick up boards to be tested so you can just give it a stack and it would automatically test and sort them.

[denelec]

How much will this robotic arm cost?  Didn't see the price.

This robotic arm seems a bit better.
http://www.robotshop.com/en/lynxmotion-al5d-robot-arm-combo-kit-4dof.html

[GiskardReventlov]

Connect the UART pins on the Bus Pirate to pins 0 and 1 on the Arduino in the robot.

I think this could be done on the oscilloscope. If so it would be more interesting.

[Jimmy]

G Dave long time lurker here. I love the vid thank you for sharing.  Keep up the good work and ignore the haters.

[HackedFridgeMagnet]

Well the arm would be good to start learning robotics with. And I dont think it could accidently kill you unlike some of the bigger ones.
6 axis would be better though.

[FrankT]

I've been building mine for a while.  If I ever get it finished, the first task will be to sort my box of through hole resistors.

[electrolux]

That u arm is rather disappointing' I'm not impressed.

[GiskardReventlov]

That u arm is rather disappointing' I'm not impressed.

Agreed, but sounds like the team is young. But it looks like they didn't study what's out there. I have a desk lamp and the mechanism is more stable than this uARM. It's got the arms parallel in the vertical.  The next iteration better look a lot different. They need to study what engineers before them arrived at and understand why. I hate to say it but it's the arduino syndrome. Too much nuts-and-bolts stuff is already done for them and people end up with unclear understanding of what they've built and why it behaves as it does.

[Jimmy]

It looks as if it is not open source yet and now that the kickstarter has been funded and they are selling kits on their website are they going to open source it?

[Jimmy]

Still not opensource maybe someone could take it apart and scan a copy of each part for us?

[FrankBuss]

Still not opensource maybe someone could take it apart and scan a copy of each part for us?

Sorry for reviving this old thread, but here you go, see question 2. This is for the new uArm Metal version, which seems to be a bit more stable than the one Dave tested. But the motions look still a bit jerky too me, and not good position repeatability. And the metal version cost now $339.

A professional robot, like this one, has a repeatability of 0.005 mm:



Problem is it costs $15,000.

I'm searching from time to time for a good low-cost robot, something between the quality of an Arduino-servo-learning robot and the super high precision of an industry robot, and couldn't find anything. But now there is an arm for $1,159, with a repeatability of 0.2 mm, Dobot Magician. Independent review, see 7:12 how it can be used as a pretty good plotter:



And they even claim 0.02 mm for their latest product:

http://dobot.cc/dobot-m1/product-overview.html

But this costs $2,999. Still cheap for the performance, if it is as good as specified. Note, I'm not affiliated with the dobot company, and I don't have one (yet), but it looks cool.

Are there any other good robot arms in the $1k range or below out there? Maybe with 0.5 mm repeatability for $500?

[Barny]

I don't knew why, but 0.005mm and 0.02mm repeatability sound a little bit optimistic.
Even the smallest change of temperature have an effect at this accuracy levels.
Don't talking of the wear of gears and bearings.

[FrankBuss]

I don't knew why, but 0.005mm and 0.02mm repeatability sound a little bit optimistic.
Even the smallest change of temperature have an effect at this accuracy levels.
Don't talking of the wear of gears and bearings.

Maybe that's if the temperature doesn't change too much and not for millions of repetitions, but looks like at least the industrial robot can do it already:

[Barny]

It is able to do that.

The Question is, will it be this accurate under load?

I can't be helped to see this robot as nice little toy

[Dubbie]

Also very very suspicious of the accuracy claims. A big solid cast iron machine tool can only just hit those tolerances.  I think they must be measuring on the exact same path with zero load variation.


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[Koen]

As usual : repeatability isn't accuracy, should tend to 0 anyhow, gives no insight on the build quality, is only useful alone to the marketing department and so on.

[FrankBuss]

As usual : repeatability isn't accuracy, should tend to 0 anyhow, gives no insight on the build quality, is only useful alone to the marketing department and so on.

You mean for the Dobot? It is at least as accurate that you can draw pretty clean text with a pen with it. I doubt you can do this with the uARM, the motion is too jerky. And I'm sure the Meca500 is standard industry quality, build quality as good as the big ones (Kuka etc.), only less possible payload, and costs too much.

[Koen]

No, in general. If a manufacturer makes a claim for repeatability but not accuracy, it's crap. Repeatability tends to zero unless you're terrible at what you do and is an easy claim to make for the marketing department but it provides absolutely no value to the buyer as-is. 0.00001mm repeatability and no accuracy figures means you could be wrong by 5mm every time, but always wrong in the same way. And interesting repeatability claims should come with environment and time data. Nobody cares about the repeatability of a new machine in perfect conditions, it should be 0. What's interesting is how it operates after a few months/years or in its potential production environment.

[HackedFridgeMagnet]

Nobody cares about the repeatability of a new machine in perfect conditions, it should be 0.

What machine is that? I'll buy it. 

[H.O]

No, in general. If a manufacturer makes a claim for repeatability but not accuracy, it's crap.

In my limited experience it depends... Having a bit of experience with KUKA robots I have some literature right in front of me (general sales brochures and technical documents for the specific robot I'm currently working on) and neither of them state accuracy, only repeatability. I wouldn't exactly call KUKA crap....

I'm sure they DO have accuracy figures available but it's not what they're specifying in their sales brochure or in the 26 page technical data sheet I have here.

Now, if you're talking about machine tools (mills, lathes etc) then it's another thing all together. There absolute accuracy means a lot more than repeatability.

[Koen]

It's in extra documents because it depends on the region in use, regions crossed, movement sequence, application, load type, load weight and more.

This is just my usual, simple and boring warning for people shopping for their first CNC, whatever it is : repeatable doesn't mean accurate.