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First, this really belongs in lugnet.technic and lugnet.build - I think maybe people who have built controls for pneumatics might be interested as well. FUT to the two aforementioned groups added - I have left the lugnet.general newsgroup in order (...) (23 years ago, 20-Mar-01, to lugnet.build, lugnet.general, lugnet.technic)
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| | Re: Analogue Control of Pneumatics
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(...) Oops! Sorry about that. (...) Just to clarify my original post. I am interested in more exact control of both position and applied force. I am interested in trying to build mechanisms found in read life things like cars and was thinking about (...) (23 years ago, 20-Mar-01, to lugnet.build, lugnet.general, lugnet.technic)
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| | Re: Analogue Control of Pneumatics
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"Alvin Telanco" <78of560001@sneakemail.com> wrote (...) like (...) Hi Al, what you ask is not possible because the Lego pneumatic system is, precisely, *pneumatic*. In real life cylinders that are designed for position control are hydraulic and not (...) (23 years ago, 21-Mar-01, to lugnet.build, lugnet.general, lugnet.technic)
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| | Re: Analogue Control of Pneumatics
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In real life pneumatic is not used where more than two position is accuired, and when it is done ither more pneumatic cylinders are placed after each other to make more fixed positions. Or there is placed an hydraulic brake on the cylinder to holde (...) (23 years ago, 21-Mar-01, to lugnet.build, lugnet.general, lugnet.technic)
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| | Re: Analogue Control of Pneumatics
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This is really interesting. There are definite differences between pneumatic and hydraulic systems. I dreamed of Lego hydraulic systems before, but I have never anything of it. Could you please give more info on what you did with you Lego hydraulic (...) (23 years ago, 21-Mar-01, to lugnet.build, lugnet.general, lugnet.technic)
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| | Re: Analogue Control of Pneumatics
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(...) I haven't made anything whith that system yet, the observasions was made on a test setup, but i am thinking on makeing an stational robot arm with it, sinse it has to be connectet with the water tank. To illustrate the setup i have just made (...) (23 years ago, 21-Mar-01, to lugnet.build, lugnet.general, lugnet.technic)
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| | Re: Analogue Control of Pneumatics
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To make LEGO properly hydraulic, some kind of real hydraulic fluid pumping system would be needed. And it would have to take either water or a special hydraulic fluid. I believe it may be possible to achieve control with airflow alone. But I would (...) (23 years ago, 22-Mar-01, to lugnet.build, lugnet.general, lugnet.technic)
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| | Re: Analogue Control of Pneumatics
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(...) Also made more difficult because the displacement at the connecting rod end is less than at the other end, and it also tends to leak more, especially when under pressure. ROSCO (23 years ago, 22-Mar-01, to lugnet.build, lugnet.general, lugnet.technic)
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| | Re: Analogue Control of Pneumatics
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(...) Ok. So you can't do it with pneumatics. Looking around for alternative ways of making a power steering mechanism, I found this link (URL) which gives an RCX based motor driven mechanism that might be of interest to others. Al Telanco (23 years ago, 22-Mar-01, to lugnet.build, lugnet.general, lugnet.technic, lugnet.robotics.rcx)
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| | Re: Analogue Control of Pneumatics
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(...) I wouldn't say that at all. Its just that you'd need a good supply of compressed air (there's plenty of compressor designs about) and a good feedback mechanism. This is by no means impossible - just a bit tricky. ROSCO trimmed lugnet.general (...) (23 years ago, 22-Mar-01, to lugnet.build, lugnet.technic, lugnet.robotics.rcx)
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| | Re: Analogue Control of Pneumatics
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Whoa. Not entirely correct. You can do accurate positioning with pneumatics, it's just harder to do than with hydraulics, because you have to take air compressiblity and seal "stiction" into account if you want to hit an arbitrary position that's (...) (23 years ago, 22-Mar-01, to lugnet.build, lugnet.general, lugnet.technic, lugnet.robotics.rcx)
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| | Re: Analogue Control of Pneumatics
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Hi I did some 'research' in this area about three years ago for the control of a pneumatic robot arm. It was quite simple positional control ie position the piston at any point in the cylinders stroke and hold it there. The controller was just a PC (...) (23 years ago, 24-Mar-01, to lugnet.build, lugnet.general, lugnet.technic, lugnet.robotics.rcx)
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| | Re: Analogue Control of Pneumatics
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Yep, and if you combine those high-speed, high-precision pressure regulators with low stiction cylinders and a fast PID controller you can get even better accuracy and repeatability. When I was working for an encoder company, I scavenged some parts (...) (23 years ago, 25-Mar-01, to lugnet.build, lugnet.general, lugnet.technic, lugnet.robotics.rcx)
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| | Re: Analogue Control of Pneumatics
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Perhaps TLG should be meeting companies that produce valves of the same quality as those mentioned. It also sounds like the timing belt used for the test bed could be replaced or reinforced even more. -- Cheers ... Geoffrey Hyde "Xanthra47" (...) (23 years ago, 25-Mar-01, to lugnet.build, lugnet.general, lugnet.technic, lugnet.robotics.rcx)
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