Advanced robotics

Let me see if I understand what you are proposing.
1- A set of coils causes a mechanism to clamp onto the ribbon. 2- Once clamped, a second set of coils is energized and moves the clamp (and ribbon) a very small amount. 3- At the end of the motion, a new clamp secures the ribbon at the new position 4- The first clamp releases and is moved to the original position 5- The process is repeated.
It's a microstepping motor.
Well, the first problem is that the power you'll be able to generate is proportional to the strength of the magnitic field. This, in turn, is related to how much iron you have. If designing a DC motor that's one of the limiting factors. Bigger magnets don't get you more power without more iron. If you are not going to have any magnets then the field strength has to be generated by burning energy, which is not very efficient at all.
I like high performance DC motors. If properly designed and operated they can run at efficiencies apporaching 90%. That's pretty good. Still, if you'll need, say, 5000W to run a robot full of motors, that means that you will be burning, at the very least, 500W in wasted energy. The number is probably many times worst due to the fact that all the other elements involved will not operate at 100%.
Here's the funny thing. The mechanism you are proposing is almost exactly how motion picture cameras work. Of course, this is done off a single motor and using sprockets. The film is clamped between two plates. Claws engage the film's sprockets. The clamp is released. The claws pull the film down the the next frame. The clamps are activated again. This happens over and over again at whatever frame rate the rig is being operated at. Lookup "Geneva mechanism" on the web. I would suspect that this approach (meaning, a single DC motor with some mechanics) is much, much more efficient than what you are proposing. Efficient in terms of energy in -> energy out.
On a different end of the scale, ultrasonic motors can be thought of operating on a very similar principle. I think they are really inneficient though. Years ago I heard that a consumer camera (Cannon) used an ultrasonic ring to actuate focus on the lens.
I do think that the secret is in small motions. Magnetics gets interesting as the air gap is reduced. The biggest challenge yet might be that of manufacturing something like this that can run these clamp-pull-move-clamp-reset cycles at thousands of times per second and last.
I look forwards to seeing what you are going to post. Do you have any video of a prototype in opeartion?
Reply to
Martin Euredjian
Loading thread data ...
From reading the threads, it seems that all Bruce is asking is for people to come to the Yahoo group and see if they would be interested in helping, leaving the decision to them once they have the information. If that isn't backing up claims then I doubt that any picture or video would do better, since they could be all too easily faked ( I know, I've seen enough of them).
As a matter of fact, I find it very refreshing that someone is coming in with an open attitude, since typically these kinds of technical discussions are always too guarded due to the sensitive nature of the application and/or lack of (thought)/(common sense) in today's "high technology" (my personal feeling). It would seem that it could not get much more direct or open than asking if you want to help and be a part of it.
.02, for whatever that's worth (probably not much )
Reply to
xTenn
Are there any digital cameras that are useful? NTSC is nice for putting on a screen, but not too easy to use. I'd like to see something that reads out like a ram array.
Reply to
Dave VanHorn
Clear enough. I think we're both sceptics of this guy's claims.
Yes, they're outlandish. I don't think he has the technology developed to a usable degree. Actually, what I've seen on his yahoo group is an electro-mechanical stepper motor/linear motor. I can imagine that it will suffer from severe friction, noise and be power-hungry.
If Bruce wants to develop the technology, he should do the math on the theoretical limits of his device. Then he will see where the problems lie.
As for the issue of "next generation," perhaps you should review what a generation might be. A generation might not be complete accomplishment of the goal, but merely a single advancement towards it. To me, a generation is about 4 or 5 years. Where will robotics be in 4 or 5 years? Therefore, CMOS sensors are legitimate technology for the NEXT generation (but probably not for 5 or 10 generations to come).
I don't think I was way out of line at all. Your statements about your opinions of him were the same as mine. My opinions were justified. If you read my statements, they were in the past-tense. I was not accusing you of being a troll-assistant, I said I thought (past tense) that you might be. I no longer think that.
The issue is experiences with watching newsgroups get taken over. My claim was that I thought this was one of those instances and therefore my point about observing years of newsgroups was support for my claim about being knowledgeable about such things.
Anyways, you and I are on the same side. We should set a policy together of de-escalating conflict so that we can work together to ensure that there isn't any trolling going on.
Good.
Look, perhaps the guy doesn't have the skills necessary for public discussion ( I think that's obvious ). However, you and I both agree that he made outlandish claims. I went to his yahoo group to see what information existed there. As such, I'm a little more satisfied that Bruce probably isn't malicious, but merely needs to learn some things.
Bruce needs to understand that there is a standard mode of public dialog which obligates those who make a claim to support their claim (most likely in the same arena that the claims were made). This is standard public communication and science reporting technique.
Bruce has been deficient in this aspect. He has made claims on this newsgroup but he has not provided adequate backup for his claim as he is obligated to do. People have openly challenged him and he has not responded appropriately.
Yes, the task is immensely difficult. I think that Mr Bruce has a lot to learn.
Cheers, Ed L
Reply to
Ed LeBouthillier
Although I have not tried it (and this is, therefore not an endorsement of the product), MVS has a cheap frame grabber that might be nice to use.
formatting link
Additionally, there is the CMUCam:
formatting link
It is available at a number of commercial outlets.
EdL
Reply to
Ed LeBouthillier
Martin, The enabling factor is the distance, not how much iron. And this isn't like a sprocket and stepper. Magnetic fields are a >>product
Reply to
Bruce
Ed, It does need work. That is why I thought a Team could take it where it needed to go. I know that I can't alone.
To make it available to everyone, that is the reason for making it "open source". For everyone's benifit..for it to go where we all want it to go.
And thanks for the pat on the back (and the iron skillet over the head...definitely need the skillet ;o).
Bruce
Reply to
Bruce
You don't understand. For any given distance, the magnetic field strenght you are going to develop will be limited by iron. The second limit is operating tempreature (heating). You can use the best neodymium magnets if you want, but, if you don't have anything to carry that flux you are not going to produce decent results.
The energy equation for what you are proposing doesn't look good. I wish I had the time to do a real analysis. I can't, I've got a big project I'm busy with. But, just from experience, I just don't see how you are going to beat a good PMDC motor with gears in terms of efficiency. For every step you'll have to expend energy compressing and/or expanding springs.
Which leads to a question: Have you done the basic Physics 101 analysis of this thing? You need to show that to people in order to show some merit. The contraption can be made to move, of course, but, is it worth spending any time on it? That can be seen from basic principles.
There's also this business of kevlar in the airgap, which is not a good idea at all. There are better ways to do it. You do not want nor need kevlar in the airgap. Bad idea.
And, why do you need a pair of coils to clamp/move? One is enough. In fact, the whole contraption can probably be made with just two coils, not three.
Of course, the smaller the stepper motor's motion the worst your problems might become. At that scale things might bend and stretch in magnitudes significantly proportional to the mechanics of the motion itself. There's also thermal behavior to consider.
You need to put some Physics/Math on paper and see what you've got.
-Martin
Reply to
Martin Euredjian
I have to apologize. As I am not in the consumer market I truly don't know what's available out there. Maybe someone can provide some ideas.
At the very least you want a progressively scanned imager (to avoid motion induced interlacing artifacts), as high a frame rate as your processing can handle, a digital interface and a full RGB color space (as opposed to YCbCr or YPbPr). Now, this will be expensive. If you are a hobbyist you might as well stick with some of the canned solutions as they are fun and cheap. If you can find an inexpensive progressively scanned camera go with that.
Maybe you can search Ebay for indusrial imaging cameras.
Reply to
Martin Euredjian
I am just concerned here, and perhaps it is a fault on my own part, but it appears( and I underscore appears) that every time a thread in this post gets too deep, it gets dropped. ( my news reader is less than adequate), so this may be my skewed version.
Your appearent reluctance to disclose your project in detail in this public forum leave me feeling uneasy. You have spoon fed us little pieces here, including the basic concept of your synth muscle. Could you please, for the sake of us all, post a digest of what you have revealed here, and perhaps everything else that you are willing to reveal.
This is my impression:
self contained "industrial" humanoid biped
Distributed processing, assumed to be serial, 2 mbps. Sub pocessor board needs to run at a bus speed of 20mhz. Sub processor board needs 3 x 10khz PWM to 3x 40 khz, Sub processor board needs power circuitry of 15 A, hundreds required ( Don't know if that is total aperage) ( Don't know what the bus voltage is) I think I read that you plan to water cool things?
3 phase liner motor, without rare earth magnets, just copper on copper, minimal air gap.
low resolution cmos images ( like 640x480)
I am not willing to join Yahoo groups because of the spam issues there, so I realize I am posting in a bit of a vacuum. I do wish to err on the side of caution when looking at your project, but your tactics make me feel uncomfortable. Generally, since this is a pulblic forum, we discuss things, well, publicly. Your responses seem to skirt different issues, leave incomplete answers, etc.
Part of what makes me feel uncomfortambe is that you use your own vernacular in your postings. SynthMuscle, FSys boards, AFAP (which I later figured out). If it is a 3 phase linear motor, call it that. There is a person here who posts regarding A.I. based on FORTH. I dare not invoke his name, because then this thread will be shot to H***, but he comes across as a complete nut job because he discusses his project in his terms, and assumes that everyone else can follow. He hides behind his own terminology, and won't discuss things in simple terms. Your project has a hint of that flavor.
Please understand, these are my own personal feelings, and I am only expressing them for your benefeit, not because a I am some bridge dweller. I am intrigued by your project, wouldn't mind helping, but I wanted to air my trepidation. Believe me, I have better to do than be a flamer or a troll. I have a literally 10 projects brewing, some with 4 year development times that are better served by my not being a news group Don Qixote, tilting lances with imaginary foes.
Again, I caution that this may be my skewed version.
Thanks
Mike
Reply to
Blueeyedpop
Mike, here is your alternate access point:
formatting link
Reply to
dan michaels
Sayeth Blueeyedpop :
Yeah, it's a bit of a kook filter across all fields ...
Also, having heard the description of SynthMuscles, they _do_ sounds a lot like linear motors, perhaps ultrasonic[1] ones. In which case I have to ask ... what is all that per-muscle CPU power doing?
-----sharks
[1]
Reply to
sharkey
Mike, Please, don't apologize. If anyone should, it is me. My communication skills leave a LOT to be desired. I have spent way too much time in the workshop and very little time with people. I sincerely apologize for my structure of speech and crude language. And I really do appreciate what you have said.
There are many problems with the initial design. But it is only an initial design.
Yes, there is way more processing power in the SynthMuscle (probably a bad term, but that is the function it is doing...linear motor doesn't describe it...ribbon wench doesn't describe it...I don't know what else to call it...I'm sorry) because it also does calculations for rate of power output over time. Also, when pulling on the ribbon, the algorithm must be an expiratory pulse (not just an arbitratry pulse but aligned with the current function).
The bus (I call it AFAP because it allows all of the clients and hosts to operate "As Fast As Possible" with varying data paths 1,2,4,8...again probably a bad term but there isn't another name I can find that describes it) it integral to allow localized iteration for movement. It basically synchronizes using a few lines to allow broadcast and localized communication (such as flashing all the PICs for updates) for clients that are interrupt and non-interrupt driven. And this is only for motion control. We are planning a discussion for September 6th at 11am EST just to cover the bus.
Certain parts, such as the big processors will need to be water cooled. The rest is planned for running low pressure air lines (crude, but effective).
Let me state very clearly, this is not a "synthetic human", this is not an "A.I. wonder", this is not a "what-ever-you-might-fancily-call-it-over-glorifier". This is a "Utility Class" droid. Some keep trying to make George 1.0 out as a robotic version of a F-50 Ferarri...I'm thinking hammer. We could all use a good hammer.
Bruce
Reply to
Bruce
Sharkey, I'm sorry for my bad terminology. I don't know what else to call the darn thing. Ribbon wench (not a wench), linear motor (not a linear motor),....what does it do, well it is suppose to be a "simple man's attept" at a synthetic muscle. Tell me what to call it and I will only use that term.
The extra processing is there because power output is given as a set of coefficents of a quadratic equation and range for a given time. Also, the pulses must be aligned with the given step, so the must function as expiratory. There is probably a better way, but it works.
The Joint Controller, just a PIC regulating two or more "thingys" (SynthMuscles), also check position and are trying to constantly readjust to keep in a range that is acceptable. The Joint controller is given coefficients and range for a given time of a quadratic equation, plus a tolerance, that is the position that joint is suppose to be near.
The communication is a plan-attempt-succeed/fail-replan interation. There is probably a better way, that is the reason for the Team.
Bruce
Reply to
Bruce
Martin, Yes, I have done the math. I have done the real world work (much more enlightening). I have tried other ways. This is best I have.
Not everything is about iron. It is about field lines, force, and most, most, most importantly scale.
Pick another material, besides kevlar that can handle the requirements (don't even go down the carbon fiber path please...been there). Tell us a better way. If you think it is a bad idea, then improve it.
Bruce
Reply to
Bruce
Sayeth Bruce :
G'day Bruce, it's not that there's anything _wrong_ with calling it whatever you want. People, myself included, just tend to be very cautious about new ideas, especially new ideas that are totally out of the blue.
The other scary thing is that the scope of your project is just so enormous, all the way from a new motor technology right through to a very advanced application. Maybe it'd be better to concentrate on one thing at a time, eg: getting a single SynthMuscle set up lifting and lowering a weight a million or so times on the test bench.
------sharks
Reply to
sharkey
Sorry Bruce, you are loosing me. You need to explain to me, in no uncertain terms, how it is that you intend to produce significant force electromagnetically without closing the magnetic circuit and doing so with the right amount of iron? It's like saying that you are going to make current flow without wires. Last time I checked, the laws of physics apply to everyone.
Regarding kevlar in the gap. I said it in my prior post: Terrible idea. You do not put anything in the gap for best force/results/efficiency/etc. You need to come-up with a better way to do it. I'll continue to argue that conventionally constructed DC motors will be more powerful, reliable and efficient than your tape-sliding stepping-motor.
Reply to
Martin Euredjian
Sharkey, Yes, the scope is huge...some of the approaches are new...but it is not impossible (maybe highly improbable, but not impossible). I make no illusions to the difficulties.
The SynthMuscle has been through a bunch of tests and abuses. It hasn't hit that 1 millionth lift, but thanks for the idea.
A group can have subgroups all focused on one thing that together make George 1.0. The "open source" approach is for everyone's benefit and is the only way this thing could be made shy of 20million.
Also, if we don't try, then we are all just sitting around talking about how great it would be if someone would try.
Bruce

Reply to
Bruce
Would the same thing apply if someone suggested how great it would be if we were to walk to the moon? Or would that just be, probably, a collossal waste of time and effort?
Reply to
Randy M. Dumse
Sayeth Bruce :
No worries. What kind of overall efficiencies are you getting out of it in practice eg: how much power goes in to lift 1 kg 1 meter?
Then just leave it doing pushups in the shed 24/7, you'll learn a lot about its wear characteristics.
Can it compete with a gearhead motor pulling the kevlar strap? Bear in mind that for a mobile robot, the power has to come from somewhere, so saving 1kg of motor but adding 10kg of battery isn't much of a tradeoff.
I quite like the 'winch' idea ... did you look at the designs of ultrasonic motors? It's not that dissimilar in method, but the ultrasonic ones use travelling waves in a machined bit of metal to do a similar thing ... which means they've got a lot more clamps, but a lot less moving parts (well, a lot less discrete moving parts)
------sharks
Reply to
sharkey

PolyTech Forum website is not affiliated with any of the manufacturers or service providers discussed here. All logos and trade names are the property of their respective owners.