Advanced robotics



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] <http://citeseer.nj.nec.com/cs?q=ultrasonic+motor&cs=1
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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

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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
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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

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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?
--
Randy M. Dumse
www.newmicros.com
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Randy, Hmmm...good questions. A preposition makes that question from impossible to highly improbable. Do you beleive a man walked on the moon?
To me, if someone was saying, "Hey, let's put a man on the moon", would sound completely nuts even with today's technology. But they did it how long ago? 34 years.
Those men and women involved in that project were true visionaires. They focused on whatever would work and kept positive. They did it despite all those against them (engineers, chemists, mathematicians, physists, and the astronauts are heros in my book and I don't give a damn who thinks otherwise :o). There are even nuts today who beleive it never happened because they can't conceive of it.
I'm no visionairy. I am trying to build a "hammer" and I need help to do that. The real question becomes, "Can you see someone building a hammer?".
Bruce

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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
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Sharkey, The efficiencies suck....around 40% at best (about like a stepping motor but much lighter...but the power-to-weight is great...hot, but great). It needs work to minimize power. Also, for power...think utility. :o)
I have a friend trying to get hold of a used magnetic-bearing microturban (5kW). Now, I know this isn't the thing you want bringing you a cup of tea in the evening, but think "Utility Class". Yes, the images just blow you away (actually the new systems are quiet and not quite how the imagination portrays them ;o)
To make up for immediate power, looking to lithium ion batteries that can be charged off the generator. Working those final details out will take some time. Know any good sources?
I like the idea of the pushups, but I am going to just program the PIC to run it to failure as soon as time permits.
Bruce

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Re: that. Can you peak-and-hold the solenoids to reduce power consumption?

Okay, but what does a "utility class" robot (was this thing meant to be a biped?) _do_? If it's going to be burning 5kW, it'd better be doing something valuable.
Is it meant to just move stuff around? What can it do that a forklift with a PUMA bolted to the top won't do better? Or, for that matter, what can it do that you can't hire for minimum wage?
-----sharks
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Sharkey, Yes, that is part of what the PIC is helping control. Part of that is an expiratory PWM.
It is to be a biped. And the 5kW is overkill (haven't found anything smaller :o).
This is just a stepping stone, nothing more. It is an "open source" baseline. What good is an Asimo? What good is a SDR-4X? Hopefully, at least George 1.0 can be of some use.
Remember, there is a reason the name has "1.0" in it. Maybe around "4.0" it will be more what we all want.
Bruce

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Oh, right. 'Expiratory' isn't a term I'm familiar with.

What good are they? Bugger all. They're PR stunts and tax sinks for large R&D organizations.
Autonomous bipedal hominids are a waste of time, because the planet is already overrun with self-repairing, self-maintaining ones. What on earth is the point imitating them?
Prosthetics, though, that'd be a worthwhile field for your SynthMuscle developments.
-----sharks
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Sharkey, For prosthetics, that is the first place they are being used. A friend of mine is quadraplegic. There is a version Limb Controller is built with a USB port (via a National 9603). It provides the PID interface.
A notebook will serve as the interface between the Arm and his mouse (specialized and mounted to his chair). He can change the programming through a VB program acting as the Central Controller.
There is a great need to a Utility Class droid. There will be bad uses, there will be great uses. It is just a tool, like a hammer.
Bruce

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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

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Robin, The SynthMuscles do create a number of problems. But, they also solve so many other problems that are otherwise unsolvable with conventional technology. I think you will come to find out that SCALE is a all important aspect of design. (unless you think ants scaled to the size of elephants could hold themselves up ;o)
The use of SynthMuscles actually take up much less space and weight, but are more than twice as numerous. They also have a much, much higher power to weight ratio. They do use some very unique materials with specifications that seem unlikely (at least it seemed impossible until they were found...a set of materials to fit the math).
As for naming it, "George 1.0" is just a starting point. Within the team there are some that are debating the name right now. For me, I leave the name to the team. Some have also suggested a humanoid "face".
Personally, I no interest in making George 1.0 a friendly, human acting droid. My goal is a usable utility class droid.
Bruce

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snipped-for-privacy@yahoo.com (Bruce) wrote in message

Ah...do these SynthMuscles use the "quantum cavitation" phenomenon that was observed a few years back? A carefully balanced arrangement of materials such that electron injection upsets the stability of the outer electron shells, switching to covalent bonds which results in compression of the material in the direction of electron flow?
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Ryan, It isn't so elegant (and much more durable ;o). I tried a harmonic drive system in one of the many other attempts to make a usable SynthMuscle, but it couldn't sustain any force.
Bruce
snipped-for-privacy@macetech.com (Garrett Mace) wrote in message

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Bruce,
Can you provide more details about these "Synthmuscle's"? What's the principle of operation? How are they built? How can a hobbyist or interested collaborator get one or build one? That's the first step, in my opinon. Validate the effector technology. Without this I don't think you have a project. Seriously.
I think the single most important component missing from the humanoid arsenal is a device that can be made to behave like a biological muscle. This doesn't just mean power/weight ratio, energy storage, efficiency, etc., but also things like having the ability to form it into many shapes and sizes as well as having the device conform to the operating environment. Not to mention such things as operating noise. A humanoid with hundreds of motors might be interesting, but, if I have to wear ear protectors while it's fetching me a cup of coffee it's a real deal-breaker.
--
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
Martin Euredjian
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Martin, This is a simple device. I have been holding off details until I could get a decent sized group started (people are the hard part...you understand :o).
Bascially, the SynthMuscle is an electromechanical device. It uses two sets of coils (pinchers) to squeeze a kevlar ribbon (1/1000th of an inch thick, 1/2 inch wide) to generate friction. Two other large coils pull the ribbon being held by one set of pinchers to the other.
The distances are very tiny which enables it to work (fun with magnetic math). The actual pull distance is on average around 1/1000th of an inch.
The ribbon was the hard part. It is 200 kevlar filaments side-by-side bonded with a UV curable acrylic. In order for it to work, it had to be very thin, stretch less than 1%, be very strong, and wear resistant.
Anyone can make this thing. It is not elegant, but it does work. I will be posting the pictures, video, schematics, and notes on making one this week.
Like I said, not complex. Just a starting point.
Bruce

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I can't wait to see your pictures. But I can't help but wonder why you'd want to use coils (heavy) and magnetism (weak) instead of plates and electric fields. If new technology is being developed here, wouldn't it be more promising to explore the electric field as a purveyor of force, rather than magnetic?
- Owen -
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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?
--
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
Martin Euredjian
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