I’m agnostic on the ebay concept in general.
I’m baffled as to why we are not keeping/repairing/using the robot arms though.
The robot has been discussed at length and was voted on to sell a year ago by the committee unanimously. The robot works and was working when it was found to be far too dangerous to be used at the space. @kobin
The robot nearly tipped over and could have crushed someone, on its metal roller stand.
No one touched the robot for over 6 months before we decided to sell it. The only safe way to have the robots at the space is anchored to the ground inside of a metal cage, makerspace does not have the room or the infrastructure to support it. It is dangerous and not very practical for a place where nearly everything is custom made anyway. Yes it would be a good job training tool. but there is already another space downtown that specializes in these robots.
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@Chris_Wischowsky was planning on getting one of the robot arms up and running using a different controller. Got permission from @TBJK a while back to spend $100 on a single axis driver to test the arm. The Plastics SIG could use the arm if we can aliquot some floor space. The arm needs to be bolted to a proper base so it doesn’t tip over… the current cart base is not sufficient.
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Aliquot: a portion of a larger whole (usually a sample taken in chemistry).
Huh. That… actually works in that sentence…
Task failed successfully?
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If PIG Sig is going to keep it, I feel we need to see progress on it. In addition commitments from 1 or preferably more people to train folks to use it. I dont want to see it just sit in a corner, with people asking for classes every few weeks without people to train them how to use it.
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I’ll be the guy, what could the plastics sig use a robot arm for?
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Passing the butter.
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Ironically that’s the first thing that came to my mind when we first got it. Wasn’t really sure of usability.
Chris was thinking about putting a small spindle on it for trimming plastics, If I recall correctly. Obviously it was early in the stages when we shut down. I’d damn near forgotten about it until it was brought up in this thread.
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Have you been in automotive or the machine shop ? Ever ?
If a new base is needed, that’s doable. Safety enhancements - doable.
That there is another space that has them is not relevant.
If no one has time or resources to get it done at DMS, then we’ll have another missed opportunity. Regrettable.
That it’s a dangerous tool, or that another space has one are not reasons for us to not have one though in my opinion.
It takes up a lot of space to operate safely that several committees are not willing to sacrifice for the robot arms. Also besides the plastics guy(that had recently asked about them before shut down), no one has been willing to put in the work to get them running. They have been laying around for 1.5 years doing nothing. Jim i believe has worked with them in the past and says with the current controller it just isn’t worth it. If the plastics guy wants to take up the initiative, he should do it soon because we dont want them sitting around for another year and half while nothing gets done with them. Science has been trying very hard to get cleaned and organized and they are huge and in the way.
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IIRC, that robot arm requires 208V 3phase.
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The tag on the controller shows “3x 400V - 50/60hz - 2800VA”
Not sure of the power requirements for the new open source driver.
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That’s a standard European voltage but we don’t have it anywhere at DMS to my knowledge, it would need a transformer.
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I worked on the arms and helped get them to a workable state, such as they are. The controller is very old and some of the software works.
They have adjustable taps for voltage and it is configured for 208v 3ph.
Alot of the documentation is on the committee drive, including alot of manuals and code.
There should be a 208v 3ph outlet next to the plastic area in Hatcher’s or at least it was ordered. There also should be a longer extension cord on the cart. The cart is NOT a good stand to use the arms and they need to be mounted somewhere solid as they can produce alot of force.
If you have any other questions, let me know.
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Also… here are a few more links
Servo Controllers we were considering building for a new controller. I would look for the latest revision.
Original Post with alot of info
Wiki page on the Arms
Committee Drive with lots of info, including hard to find manuals
- N:\Science\Robot Arms
We also were considering using this as the software.
We solved the " Unexpected PSS state" error by repairing one of the front panel switches.
I helped to get the Robot arm working. It probably does not require 3 phase because the AC is rectified to DC for servo use, and the incoming voltage can be adjusted using the transformer taps. Having worked a fair amount on it I disagree that it is too dangerous. It has a surprisingly low stall torque which is in the documentation. If anyone can retrofit it it is Chris. If we keep it, I would recomend welding a steel base that can be moved with a pallet jack.
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According to Andrew Boerder “industrial ac servos with just a few exceptions are all triphasic brushless motors.”
I see the confusion. AC -> DC -> AC. The servo drive re modulates the DC bus to variable frequency 3 phase AC.
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It’s certainly possible but something that needs some research first. For the same load, the remaining two diode bridges will be conducting notably more current (we’d need to make sure they’re sufficiently oversized) and the ripple on the DC Link will be significantly increased. Three phase power has relatively consistent power and results in fairly low ripple even through a simple six pulse front end. Single phase power has zero power at the zero crossing, so it exhibits a large power ripple and single phase rectifiers need much more DC link capacitance. We should make sure the increased ripple doesn’t interact with the servo controllers as it can often make closed loop control unstable.