I'm looking at the enclosure requirements.? I understand from Gordon that commercial ventilators use some variation of Luer Lock fittings.
Does anyone know definitively what kind of fitting we should use for the metering air circuits for the pressure transducers?? What diameter tubing have we settled on for the metering air circuits?
I'm looking for?preferably a bulkhead mount fitting that can attach to the chassis.? The inside fitting would preferably be barbed and?connect to the on board pressure sensor by a short length of tubing.? The pressure sensors have a size tolerance of .115-.125 port diameter so I believe 1/8" ID tubing? is appropriate.??
Keep in mind that the smallest ID tubing will give the lowest volume and therefore have the highest dynamic response.
As there are?three fittings. I wonder if different sized fittings should be used to prevent installing the wrong tube in the wrong port.? Is there any standard for this?
As a secondary question the UF prototype appears to be using a shop air chuck to supply the compresed air to the regulator.? Is there a standard "air chuck" in use in hospital rooms for the air supply?
73,
Mike N8WFF
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Re: Help on boot loader‘s?
Jack has covered both the issues.? I use the chinese arduino nanos all the time. we flew three of them to space. they are reliable. they mostly have a problem with the drivers.? - f
The two most common problems are not having the CH340 driver installed. Try:
The next most common problem is when there is an old bootloader. If this happens, usually there's a menu option under "Tools" where you can select "Old 328 bootloader". If you see that menu option, try clicking on it.
Jack, W8TEE
OK, need to call on all of you experts once again.
we are having troubles with one particular batch of Nanos ?not being willing to be uploaded new code.
this batch of three did not seem to have a boot loader on it, so I followed instructions on the Internet and used an Arduino Uno to load a boot loader on to them, following which they initially ?seemed to work.? However, we have had intermittent problems getting the IDE to load to these Nanos.?
anybody have something we should check? ?we have also made sure that we have the right comport, right type of device, I have suggested to the gentleman having trouble that he check com port speeds at Cetera at Cetera and we are a bit perplexed ??
suggestions?? You guys have been great, answering lots and lots of issues quickly
?
?
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Thank you .? ?That is basically identical to what the FDA is sending out (which is enclosed)
On Sun, Apr 12, 2020 at 9:42 PM Christopher Bass < bassc@...> wrote: This might be of interest.. a draft copy of Emergency Use Ventilator Design Guidance from the Association for the Advancement of Medical Instrumentation (AAMI).
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This might be of interest.. a draft copy of Emergency Use Ventilator Design Guidance from the Association for the Advancement of Medical Instrumentation (AAMI).
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Re: Help on boot loader‘s?
The two most common problems are not having the CH340 driver installed. Try:
The next most common problem is when there is an old bootloader. If this happens, usually there's a menu option under "Tools" where you can select "Old 328 bootloader". If you see that menu option, try clicking on it.
Jack, W8TEE
On Sunday, April 12, 2020, 4:56:17 PM EDT, Gordon Gibby <docvacuumtubes@...> wrote:
OK, need to call on all of you experts once again.
we are having troubles with one particular batch of Nanos ?not being willing to be uploaded new code.
this batch of three did not seem to have a boot loader on it, so I followed instructions on the Internet and used an Arduino Uno to load a boot loader on to them, following which they initially ?seemed to work. ?However, we have had intermittent problems getting the IDE to load to these Nanos.?
anybody have something we should check? ?we have also made sure that we have the right comport, right type of device, I have suggested to the gentleman having trouble that he check com port speeds at Cetera at Cetera and we are a bit perplexed ??
suggestions? ?You guys have been great, answering lots and lots of issues quickly
?
?
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Re: UQ Ventilator Design Hackathon
Hi Marcello, I am moving in the direction of a stepper motor (no pun intended) to drive my bellows pump. Unfortunately, I am involved in too many things now and Still waiting for some parts.
Here are my comments: - I found out that I you do not need a very powerful stepper motor to drive a bellows type pump, if you use a screw-type drive mechanism. The screw mechanism?provides tremendous mechanical?advantage to provide the necessary torque.
- I found out that rough pitched drive screws are better for the purpose than fine pitch ones (typically used for 3D printers and CNC machines).
- Utilizing the built-in hardware timers in the AVR MCU chip, utilizing a timer interrupt based pulse generator can save CPU resources.
- Considering how cheap Arduino Nano is, it may be worth using one that is dedicated to controlling one or more stepper motors (pump, gate valves, etc.) and using high level commands sent through the serial ports between MCUs.
- Interestingly, large pitch screw drives are mostly available for larger size screws. I had to choose a 12mm screw instead of 8mm to get a 1.5:1 pitch increase.
I hope that my information helps.
--Ron N7FTZ
Thanks Marcelo.?
Will do!?
Do you have a link to the repo?? On Mon., 13 Apr. 2020, 4:52 am Marcelo Varanda via , <mv_email= [email protected]> wrote: You may consider to send him this demo:
Still work in progress... I am focus in other components right now but I want to optimize the LCD library.
Stepper motor requires high CPU usage when using high precision and LCD driver as most Arduino libraries are not designed for real-time application at all.
But is definitely feasible as shown in this video.
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Re: UQ Ventilator Design Hackathont
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Fantastic progress, I spent the last two hours trying to make sense of FDA standards, I’ll hunt down your code early tomorrow morning and load it and give it a shot. ? ?Thank you so much for working on it!
What I saw in your video it looked extremely good.
Then I have to read about 300 pages of IEC standards, Hunting for anything that applies to what we are doing. ? ?And that is only one of the ones, but it is the only one that we currently have.
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On Apr 12, 2020, at 19:31, Marcelo Varanda via groups.io <mv_email@...> wrote:
?New parameter to setup pressure and flow limits:
Have fun,
MV
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After an hour-and-half of workiing on this? I recognize that we have ONE out of about SIX standards that the FDA refers to.
We have IEC 60601-1? ?called the "General Standard" by the FDA.
They list about five other standards that are more "particular" standards and we don't have them yet.??
Principal among those appears to be:??ISO 80601-2-80? ?with -2-12 and -2-17? also mentioned prominently.
If you know something ABOUT these standards beyond what i can find on Wikipedia, I'm all ears......
Thanks
gordon
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New parameter to setup pressure and flow limits:
Have fun,
MV
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Re: Help on boot loader‘s?
Gordon
Probably already answered, but there are different boot loader software.? Older Nanos? came with what is now called the "old boot loader".? Newer Nanos come with a newer? boot loader.? There are "other boot loaders" floating around the Internet. Some are OK,? some are difficult.
Lots more info available on the web.
Arv _._
OK, need to call on all of you experts once again.
we are having troubles with one particular batch of Nanos ?not being willing to be uploaded new code.
this batch of three did not seem to have a boot loader on it, so I followed instructions on the Internet and used an Arduino Uno to load a boot loader on to them, following which they initially ?seemed to work.? However, we have had intermittent problems getting the IDE to load to these Nanos.?
anybody have something we should check? ?we have also made sure that we have the right comport, right type of device, I have suggested to the gentleman having trouble that he check com port speeds at Cetera at Cetera and we are a bit perplexed ??
suggestions?? You guys have been great, answering lots and lots of issues quickly
?
?
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Re: UQ Ventilator Design Hackathon
Thanks Marcelo.?
Will do!?
Do you have a link to the repo??
On Mon., 13 Apr. 2020, 4:52 am Marcelo Varanda via , <mv_email= [email protected]> wrote: You may consider to send him this demo:
Still work in progress... I am focus in other components right now but I want to optimize the LCD library.
Stepper motor requires high CPU usage when using high precision and LCD driver as most Arduino libraries are not designed for real-time application at all.
But is definitely feasible as shown in this video.
|
OK, need to call on all of you experts once again.
we are having troubles with one particular batch of Nanos ?not being willing to be uploaded new code.
this batch of three did not seem to have a boot loader on it, so I followed instructions on the Internet and used an Arduino Uno to load a boot loader on to them, following which they initially ?seemed to work. ?However, we have had intermittent problems getting the IDE to load to these Nanos.?
anybody have something we should check? ?we have also made sure that we have the right comport, right type of device, I have suggested to the gentleman having trouble that he check com port speeds at Cetera at Cetera and we are a bit perplexed ??
suggestions? ?You guys have been great, answering lots and lots of issues quickly
?
?
|
On Sun, Apr 12, 2020 at 12:47 PM, Gordon Gibby wrote:
Be aware that the gears in most RC model Controllers are plastic and they wear out
Another good point. In looking at servos, there are metal gear models for very reasonable prices, as well as high end designs. I'm starting out testing with plastic gear servos, just to get an idea if the most basic servos will work over a long period.? Tom, wb6b
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Be aware that the gears in most RC model Controllers are plastic and they wear out.....
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On Apr 12, 2020, at 15:41, Tom, wb6b <wb6b@...> wrote:
?On Sun, Apr 12, 2020 at 05:35 AM, Erich Schulz wrote:
release of plexiglass dust could be problematic
Yes, that is a good question. The valve is designed to be connected to standard "Y" circuit hoses, a disposable filter could be included. Filters are probably a good idea for any design.? The valve is designed to be computer controlled and the computer will know and control the position of the servo in degrees of rotation. There are zones on the disk to handle different modes of the breathing cycle. The computer will rotate the disk slowly I response to sensor feedback when needed and can stop on a valve closed zone or quickly skip past it. There is a zone that allows inflow to be controlled with some outflow leakage; hopefully allowing a PEEP value to be maintained. These type of servos can rotate 60 degrees in 0.1 seconds, or rotate slowly when needed. Tom, wb6b
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On Sun, Apr 12, 2020 at 05:35 AM, Erich Schulz wrote:
release of plexiglass dust could be problematic
Yes, that is a good question. The valve is designed to be connected to standard "Y" circuit hoses, a disposable filter could be included. Filters are probably a good idea for any design.? The valve is designed to be computer controlled and the computer will know and control the position of the servo in degrees of rotation. There are zones on the disk to handle different modes of the breathing cycle. The computer will rotate the disk slowly in response to sensor feedback when needed and can stop on a valve closed zone or quickly skip past it. There is a zone that allows inflow to be controlled with some outflow leakage; hopefully allowing a PEEP value to be maintained. These type of servos can rotate 60 degrees in 0.1 seconds, or rotate slowly when needed. It is possible that this valve could be inexpensive enough to be disposable. Testing will show the weak points and suggest where improvements can be made.? Tom, wb6b
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HOORAY!! ?A copy of the standards that we are allowed to peruse ?temporarily has been found! ?Thanks to everyone who worked on this, we obviously can’t put them out there because they are intellectual property that is protected.
this gets us back on track to get the submission going.
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Re: UQ Ventilator Design Hackathon
You may consider to send him this demo:
Still work in progress... I am focus in other components right now but I want to optimize the LCD library.
Stepper motor requires high CPU usage when using high precision and LCD driver as most Arduino libraries are not designed for real-time application at all.
But is definitely feasible as shown in this video.
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Bob, do you have any of these standards? ? In the document I forwarded is the list, scan for the word general standard and the list is there. ?
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Fascinating way to build a vAlve!!! What will people think of next?
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On Apr 12, 2020, at 07:18, Tom, wb6b <wb6b@...> wrote:
?On Fri, Apr 10, 2020 at 09:55 PM, Erich Schulz wrote:
Let me know if have any drawings Tom
Hi Erich, I found some cheat sheets and was able to figure out OpenSCAD well enough to produce this exploded view drawing. Basically the valve consists of five layers of plexiglass sheet sandwiched together. Likely 2.38mm thick. The top manifold layer is twice or more thicker. This is just a first rough concept drawing, with no premature optimizations included. An overpressure poppet valve and a negative pressure one way valve should be added to the valve body. A strip on enclosed foam elastomer of some sort could replace the small gap barrier across the bottom of the valve disk in the "air chamber" layer of the valve assembly.? It could be a safety feature in that it is possible to allow some play of the valve disk against the top valve plate (the layer below the manifold). The air pressure will hold the valve disk against the top plate. If supply pressure is lost and a positive pressure be exerted by the patient, or negative pressure from the patient the valve disk could lift away from the top valve plate and provide an air path. However, it will be reverse to the normal flow. Inline filters should be included in the supply and exhaust lines if enabling this "safety" breathing path is desired. I'm waiting on the RC servos I ordered to arrive to see how well this design works. Tom, wb6b ----- <Screen Shot 2020-04-12 at 3.39.17 AM.png> ----- ?
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jjpurdum
Marcelo Varanda