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Re: Group Design

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On 08/07/2020 05:36, Rick C wrote:
> On Tuesday, July 7, 2020 at 10:02:45 PM UTC-4, Paul Rubin wrote:
>> Rick C <gnuarm.deletethisbit@gmail.com> writes:
>>> Wow!  Designing in a group is strange.  I'm helping with the
>>> design of a ventilator and it is a unique experience.
>> 
>> Sounds like fun, but why a ventilator?  Is the ventilator shortage
>> still happening and are there more urgent shortages?  I thought
>> there were already a bunch of ventilator projects.
>> 
>> What is the software going to be like, and is it being taken care
>> of? This sounds like a good opportunity to write some Ada code.
> 
> Yeah, that was one of my first observations that there are tons of
> ventilator projects.  They nearly all are based on squeezing an
> Ambu-bag to push air into the patient.  The details of not harming
> the patient are tricky.  Ventilating a patient while conscious is
> harder and very few are doing that.  They seem to be having problems
> with the plumbing at the moment, getting all the right valves in the
> right places to do the right things.  At the moment there is a lot of
> hardware right at the patient's mouth.  I'm working to understand
> what is needed and what isn't.
> 
> There's a valve called a Ruben valve which allows the patient to be
> connected to the inspiratory limb (branch from the ventilator) or to
> the expiratory limb (the path for exhaling) without a leak to the
> outside via a straight through path.  It's not entirely clear just
> how the details of this valve work.  I have concerns that the valve
> can be stuck in the inhale position by the pressure in the line.  It
> doesn't seem to have a way to leak out once pressurized.
> 
> I'm not sure the software is too hard at the higher levels, but there
> are interface procedures that have to convert differential pressure
> to flow rate and monitor other marginal sensors.  The O2 sensor is
> only ~18% accurate.  The guy running the project doesn't seem to
> understand the difference between accuracy, resolution and noise when
> we were talking about increasing the resolution of a reading by
> averaging many samples.  Not that this was a big deal.  The real
> issue is I'm not sure improving the resolution of the measurement
> will give him what he wants.  The airflow measurement is very
> sensitive at the low end.  I'm wondering if there is an issue with
> the flow being more or less laminar at the low end so that it is not
> going to be an accurate reading.  The interesting part is they
> verified the home brew flow rate sensor by using a commercial flow
> rate sensor that uses the same technique.
> 
> Whatever.  I'm trying to help without being a drag.  I think
> sometimes my questions are not what they want to hear.  Maybe I'm too
> pessimistic.
> 
> The software is C I believe.  I don't think anyone in this crowd is
> going to use Ada.
> 

It sounds like this group is opportunist (I don't mean that in a bad
way) - they see a potential market for a device, with a short time
frame, and they are trying to get something working as fast as possible
before the window closes.  So they grab the first off-the-shelf "rapid"
development kit they can find - an Arduino - and start banging out code
before they've even figured out what they want to do.

For some products, that's fine.  For something medical related, it is
not.  They appear (from your description) to be missing a fundamental
understanding of the task, and haven't got in experts to cover that
base.  And without paperwork covering everything from research, design
calculations, specifications (hardware and software), reviews, project
management, issue tracking, personnel qualifications, development,
testing, certification, production qualification, and a dozen other
topics, there is no way they can get any kind of approval.

I would guess that the group is used to small systems for small
customers who are happy with a demonstration that shows the device
works.  That's great for many things, and gives people solutions that
work when a serious high-level development process would be orders of
magnitude too expensive.

But making things that are relevant to life and death is a different
world entirely.  Some people think that the current Covid situation is
so desperate that /anything/ is better than nothing, so throwing
together a cheap and simple ventilator is helpful - that is very far
from true.

So I hope you get paid up-front, and keep your distance from the group -
be an external consultant, but don't take responsibility for anything
other than your reviews.

(And the choice of language for the software is the least of their
concerns!)

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Group Design Rick C <gnuarm.deletethisbit@gmail.com> - 2020-07-07 18:46 -0700
  Re: Group Design Paul Rubin <no.email@nospam.invalid> - 2020-07-07 19:02 -0700
    Re: Group Design Rick C <gnuarm.deletethisbit@gmail.com> - 2020-07-07 20:36 -0700
      Re: Group Design David Brown <david.brown@hesbynett.no> - 2020-07-08 09:31 +0200
        Re: Group Design Rick C <gnuarm.deletethisbit@gmail.com> - 2020-07-08 07:08 -0700
  Re: Group Design Stef <stef33d@yahooI-N-V-A-L-I-D.com.invalid> - 2020-07-08 14:13 +0200
    Re: Group Design Rick C <gnuarm.deletethisbit@gmail.com> - 2020-07-08 07:19 -0700
      Re: Group Design Stef <stef33d@yahooI-N-V-A-L-I-D.com.invalid> - 2020-07-08 18:57 +0200
        Re: Group Design Theo <theom+news@chiark.greenend.org.uk> - 2020-07-08 18:28 +0100
        Re: Group Design Rick C <gnuarm.deletethisbit@gmail.com> - 2020-07-08 11:12 -0700
          Re: Group Design Stef <stef33d@yahooI-N-V-A-L-I-D.com.invalid> - 2020-07-08 23:34 +0200
            Re: Group Design Rick C <gnuarm.deletethisbit@gmail.com> - 2020-07-08 15:20 -0700
              Re: Group Design Paul Rubin <no.email@nospam.invalid> - 2020-07-08 23:00 -0700
              Re: Group Design Stef <stef33d@yahooI-N-V-A-L-I-D.com.invalid> - 2020-07-10 10:09 +0200
              Re: Group Design Chris <xxx.syseng.yyy@gfsys.co.uk> - 2020-08-07 00:01 +0100
                Re: Group Design Rick C <gnuarm.deletethisbit@gmail.com> - 2020-08-06 17:37 -0700
                Re: Group Design Paul Rubin <no.email@nospam.invalid> - 2020-08-07 03:06 -0700
                Re: Group Design Phil Hobbs <pcdhSpamMeSenseless@electrooptical.net> - 2020-08-06 21:50 -0400
                Re: Group Design Rick C <gnuarm.deletethisbit@gmail.com> - 2020-08-06 19:12 -0700
                Re: Group Design Phil Hobbs <pcdhSpamMeSenseless@electrooptical.net> - 2020-08-06 22:27 -0400
                Re: Group Design Rick C <gnuarm.deletethisbit@gmail.com> - 2020-08-06 19:36 -0700
                Re: Group Design Phil Hobbs <pcdhSpamMeSenseless@electrooptical.net> - 2020-08-06 23:39 -0400
                Re: Group Design Chris <xxx.syseng.yyy@gfsys.co.uk> - 2020-08-07 12:30 +0100
                Re: Group Design Phil Hobbs <pcdhSpamMeSenseless@electrooptical.net> - 2020-08-07 09:57 -0400
                Re: Group Design Chris <xxx.syseng.yyy@gfsys.co.uk> - 2020-08-08 00:37 +0100
                Re: Group Design Phil Hobbs <pcdhSpamMeSenseless@electrooptical.net> - 2020-08-07 20:29 -0400
                Re: Group Design upsidedown@downunder.com - 2020-08-08 08:59 +0300
                Re: Group Design David Brown <david.brown@hesbynett.no> - 2020-08-10 15:43 +0200
                Re: Group Design Rick C <gnuarm.deletethisbit@gmail.com> - 2020-08-10 09:18 -0700
                Re: Group Design Rick C <gnuarm.deletethisbit@gmail.com> - 2020-08-07 07:12 -0700
                Re: Group Design Chris <xxx.syseng.yyy@gfsys.co.uk> - 2020-08-08 00:00 +0100
                Re: Group Design Phil Hobbs <pcdhSpamMeSenseless@electrooptical.net> - 2020-08-07 20:30 -0400
                Re: Group Design Rick C <gnuarm.deletethisbit@gmail.com> - 2020-08-07 17:57 -0700
                Re: Group Design Rick C <gnuarm.deletethisbit@gmail.com> - 2020-08-07 17:56 -0700
                Re: Group Design Paul Rubin <no.email@nospam.invalid> - 2020-08-07 18:10 -0700
                Re: Group Design Rick C <gnuarm.deletethisbit@gmail.com> - 2020-08-07 19:43 -0700
                Re: Group Design Dimiter_Popoff <dp@tgi-sci.com> - 2020-08-07 20:42 +0300
                Re: Group Design Rick C <gnuarm.deletethisbit@gmail.com> - 2020-08-07 13:48 -0700
      Re: Group Design Paul Rubin <no.email@nospam.invalid> - 2020-07-08 14:11 -0700
      Re: Group Design Phil Hobbs <pcdhSpamMeSenseless@electrooptical.net> - 2020-07-09 04:25 -0400
        Re: Group Design Rick C <gnuarm.deletethisbit@gmail.com> - 2020-07-09 11:37 -0700
          Re: Group Design Paul Rubin <no.email@nospam.invalid> - 2020-07-09 11:54 -0700
          Re: Group Design Tom Gardner <spamjunk@blueyonder.co.uk> - 2020-07-09 20:02 +0100
          Re: Group Design Phil Hobbs <pcdhSpamMeSenseless@electrooptical.net> - 2020-07-09 15:31 -0400
            Re: Group Design lasselangwadtchristensen@gmail.com - 2020-07-09 15:36 -0700
              Re: Group Design Rick C <gnuarm.deletethisbit@gmail.com> - 2020-07-09 18:36 -0700
                Re: Group Design Clifford Heath <no.spam@please.net> - 2020-07-10 16:17 +1000
                Re: Group Design Rick C <gnuarm.deletethisbit@gmail.com> - 2020-07-09 23:36 -0700
                Re: Group Design Stef <stef33d@yahooI-N-V-A-L-I-D.com.invalid> - 2020-07-10 10:22 +0200
      Re: Group Design David Brown <david.brown@hesbynett.no> - 2020-07-09 14:40 +0200
  Re: Group Design John Speth <johnspeth@yahoo.com> - 2020-07-09 07:59 -0700
  Re: Group Design Don Y <blockedofcourse@foo.invalid> - 2020-07-09 18:33 -0700
    Re: Group Design Rick C <gnuarm.deletethisbit@gmail.com> - 2020-07-09 19:01 -0700
      Re: Group Design Don Y <blockedofcourse@foo.invalid> - 2020-07-09 22:32 -0700
      Re: Group Design George Neuner <gneuner2@comcast.net> - 2020-07-10 17:36 -0400
        Re: Group Design Ed Prochak <edprochak@gmail.com> - 2020-07-14 11:09 -0700
          Re: Group Design George Neuner <gneuner2@comcast.net> - 2020-07-16 00:26 -0400
  Re: Group Design Rick C <gnuarm.deletethisbit@gmail.com> - 2020-07-09 22:48 -0700
    Re: Group Design Don Y <blockedofcourse@foo.invalid> - 2020-07-09 23:53 -0700
      Re: Group Design Rick C <gnuarm.deletethisbit@gmail.com> - 2020-07-10 01:15 -0700
        Re: Group Design Don Y <blockedofcourse@foo.invalid> - 2020-07-10 02:22 -0700

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