Reply by Ricketty C August 21, 20202020-08-21
On Friday, August 21, 2020 at 1:11:32 PM UTC-4, Jan Panteltje wrote:
> On a sunny day (Fri, 21 Aug 2020 10:01:43 -0700 (PDT)) it happened Ricketty C > <gnuarm.deletethisbit@gmail.com> wrote in > <95d32c47-2cb3-40fd-aab3-7d7c5e3861ado@googlegroups.com>: > > >You are a trip. You literally know nothing about the project and yet you talk about there being no prototype, etc, etc, etc. > > Yea, you keep telling that to every body. > Consider visiting a shrink.
Show me wrong. What do you know about the project? If I am delusional, there has to be lots of evidence of it. Or are you the one who is delusional? I'm just sayin'... -- Rick C. --+- Get 1,000 miles of free Supercharging --+- Tesla referral code - https://ts.la/richard11209
Reply by Jan Panteltje August 21, 20202020-08-21
On a sunny day (Fri, 21 Aug 2020 10:01:43 -0700 (PDT)) it happened Ricketty C
<gnuarm.deletethisbit@gmail.com> wrote in
<95d32c47-2cb3-40fd-aab3-7d7c5e3861ado@googlegroups.com>:

>You are a trip. You literally know nothing about the project and yet you talk about there being no prototype, etc, etc, etc.
Yea, you keep telling that to every body. Consider visiting a shrink.
Reply by Ricketty C August 21, 20202020-08-21
On Friday, August 21, 2020 at 12:46:47 PM UTC-4, Jan Panteltje wrote:
> On a sunny day (Fri, 21 Aug 2020 08:36:27 -0700 (PDT)) it happened Ricketty C > <gnuarm.deletethisbit@gmail.com> wrote in > <8b0ef434-ffbe-48a1-95ab-d3999eb114e3o@googlegroups.com>: > > >If you understood the issues you would not make the silly, technically vague, > >alarmist comments you have made here. The issues have to do with control > >theory, not medical. There is no medical requirement to drive pressure or > >air flow in microseconds. What was the step response of the ventilator you > >designed? I will have to say I'm impressed that one person can design such > >a complex device. There are many, many facets to it and typically it would > >involve many engineers. > > > >This is a perfect example of "if you're not part of the solution, you are part > >of the problem". Why are you going on about this? If you want to contribute, > >why not actually make a contribution. If you just want to rag on things, > >please go elsewhere. > > > >There are plenty of threads here where people are just ragging on one another > >ad infinitum. It would be nice to keep the technical threads free of that. > > Rick stt > > Maybe YOU should simply build the thing, and not get lost in PID control theory. > One can easily measure air pressure and adjust the speed of a motor drive, > especially if it is a stepper, in milliseconds. > Now all you need is knowledge about the human interface to make it follow > a curve. > No PID stuff, just millisecond by millisecond adjustment against a known curve. > No long delays as in thermal heating and overshoot or big flywheels speeding up > or whatever. > Build something, test it on yourself. > Best way to get feedback and FEEL where it needs improvement. > You seem to think you are the only one in the universe who knows how to do things > you have nothing yet, not even a prototype, > math is useless in phantasy. > There is an old joke here: > How many <insert nationality here> guys does it take to screw in a light bulb? > Answer: > 5 > one to hold the bulb, and 4 to turn the ceiling. > > I have been with a big company that actually now makes ventilators for the US, > and the time from idea to production I was told there was 2 weeks. > This thread has been going on and on, > where is your prototype? > > No use trying to write code for a control system for a thing you do not even have. > Untestable, > Cool it man. > > :-)
You are a trip. You literally know nothing about the project and yet you talk about there being no prototype, etc, etc, etc. What type of acid are you on today??? This group is largely as Larkin describes it. There are on occasion a few who are willing to consider a thought. Many more here are just a scene from 2001. https://www.youtube.com/watch?v=mM6OIlreneA If you have nothing to contribute to the discussion, why post? -- Rick C. ---+ Get 1,000 miles of free Supercharging ---+ Tesla referral code - https://ts.la/richard11209
Reply by Ricketty C August 21, 20202020-08-21
On Friday, August 21, 2020 at 12:12:58 PM UTC-4, Tom Gardner wrote:
> On 21/08/20 16:36, Ricketty C wrote: > > On Friday, August 21, 2020 at 6:28:40 AM UTC-4, Tom Gardner wrote: > >> On 21/08/20 10:57, Ricketty C wrote: > >>> On Friday, August 21, 2020 at 5:36:58 AM UTC-4, Tom Gardner wrote: > >>>> On 21/08/20 06:40, Ricketty C wrote: > >>>>> On Thursday, August 20, 2020 at 9:22:01 PM UTC-4, George Herold > >>>>> wrote: > >>>>>> On Thursday, August 20, 2020 at 5:21:22 PM UTC-4, bitrex wrote: > >>>>>>> On 8/19/2020 11:05 AM, George Herold wrote: > >>>>>>>> On Tuesday, August 18, 2020 at 3:05:56 PM UTC-4, bitrex wrote: > >>>>>>>>> On 8/17/2020 11:53 AM, George Herold wrote: > >>>>>>>>>> On Sunday, August 16, 2020 at 11:14:22 AM UTC-4, > >>>>>>>>>> jla...@highlandsniptechnology.com wrote: > >>>>>>>>>>> On Sun, 16 Aug 2020 07:53:41 -0700 (PDT), Lasse Langwadt > >>>>>>>>>>> Christensen <langwadt@fonz.dk> wrote: > >>>>>>>>>>> > >>>>>>>>>>>> s&#371;ndag den 16. august 2020 kl. 16.31.14 UTC+2 skrev > >>>>>>>>>>>> Jan Panteltje: > >>>>>>>>>>>>> On a sunny day (Sat, 15 Aug 2020 22:46:45 -0700 > >>>>>>>>>>>>> (PDT)) it happened Ricketty C > >>>>>>>>>>>>> <gnuarm.deletethisbit@gmail.com> wrote in > >>>>>>>>>>>>> <d2d879c1-cf13-42f8-9727-8ef27dc2dc65o@googlegroups.com>: > >>>>>>>>>>>>> > >>>>>>>>>>>>>> > >>>>>>>>>>>>>> > >>>>>>>>>>>>> > >> > >>>>>>>>>>>>> > He shows the only difference between patient triggered and > >>>>>>>>>>>>>> machine triggered waveforms is the negative > >>>>>>>>>>>>>> pressure from the patient trying to draw air in at > >>>>>>>>>>>>>> the very start of the cycle. His diagrams are > >>>>>>>>>>>>>> pretty poor with no registration between the > >>>>>>>>>>>>>> various points on different parameters, but he gets > >>>>>>>>>>>>>> across the main points. You can do a Google search > >>>>>>>>>>>>>> to find other much better diagrams. I don't think > >>>>>>>>>>>>>> there are any new concepts to an engineer. > >>>>>>>>>>>>> > >>>>>>>>>>>>> No experience with these things but from _my_ life I > >>>>>>>>>>>>> know breathing is related to oxygen level in the > >>>>>>>>>>>>> blood. > >>>>>>>>>>>> > >>>>>>>>>>>> not really, your breathing is mostly related to the > >>>>>>>>>>>> amount of CO2 in your lungs that's why breathing > >>>>>>>>>>>> something like pure nitrogen will kill you without you > >>>>>>>>>>>> even noticing > >>>>>>>>>>> > >>>>>>>>>>> I wonder how many old ladies ricky's team plans to kill, > >>>>>>>>>>> trying to learn PIDs and stuff. > >>>>>>>>>> > >>>>>>>>>> Do you know any good control 'theory/practice' books. I've > >>>>>>>>>> got a few, but I tend to get a little lost in the Laplace > >>>>>>>>>> transforms, And would love something with a more 'hands > >>>>>>>>>> on' feel, an AoE type of book. > >>>>>>>>>> > >>>>>>>>>> Tim Wescott's book is fine. > >>>>>>>>>> https://www.wescottdesign.com/actfes/actfes.html > >>>>>>>>> > >>>>>>>>> Would you enjoy this fine series from MIT on ordinary > >>>>>>>>> differential equations including Laplace transforms: > >>>>>>>>> > >>>>>>>>> <https://www.youtube.com/watch?v=zvbdoSeGAgI> > >>>>>>>>> > >>>>>>>>> The whole lecture series is good. the Laplace transform (and > >>>>>>>>> other integral transforms too) are, in general, tools for > >>>>>>>>> solving differential equations. So a refresh on ODEs may be > >>>>>>>>> helpful > >>>>>>>> Yeah well I just replace 's' with 'i*w' (omega.. angular > >>>>>>>> frequency) and Laplace transforms are fine. My problem is > >>>>>>>> that it's easy to dig down into the math (algebra) and lose a > >>>>>>>> sense of what is going on. I sorta need the math after I > >>>>>>>> understand it. > >>>>>>>> > >>>>>>>> George H. > >>>>>>> > >>>>>>> Do you have a particular example of what in the process of > >>>>>>> "understanding" is a sticking-point? > >>>>>>> > >>>>>> Not at the moment. I've done mostly thermal loops, which are easy > >>>>>> (no thermal 'momentum/ inductance'). I guess the perennial > >>>>>> question in a thermal loop is where to put the heater/ TEC / cooler > >>>>>> (plant) and where to put the temperature sensor. > >>>>> > >>>>> Earlier it was pointed out that delays in the system can impact loop > >>>>> stability. I believe thermal systems can have such delays, for > >>>>> example, when the heater itself has significant thermal mass and the > >>>>> object being heated also has thermal mass with some thermal impedance > >>>>> between. > >>>>> > >>>>> Such a system can be stabilized by using multiple loops. A fast loop > >>>>> to control the temperature of the first thermal mass and a second, > >>>>> slower loop to adjust the set point of the first loop ultimately > >>>>> managing the temperature of the second thermal mass. > >>>>> > >>>>> I suppose a single loop with a slow response would work, but I expect > >>>>> it will require a slower response than the two loop design to deal > >>>>> with integrator wind up because the inner loop would allow the set > >>>>> point to ramp up more quickly without ramping up the outer loop > >>>>> integrator. Yes, no? > >>>>> > >>>>> Today in the conference call I explained the idea of reducing the > >>>>> overshoot by instead of limiting the slew rate of the PID controller, > >>>>> not driving it with an abrupt step function. Rather a slope can be > >>>>> used appropriate for the desired ramp up of the controlled variable. > >>>>> Rather than focus on making the controller manage the rate, give it > >>>>> the rate it should follow. > >>>> > >>>> There will be step changes when ventilating a patient. Obvious ones > >>>> are when the patient stops or starts trying to breath. > >>>> > >>>> Gently reacting to a patient that no longer inspires and expires is > >>>> likely to lead to a long-lasting expiration. > >>>> > >>>> Ditto inflating a patient that is trying to take control of their > >>>> life. > >>> > >>> You seem to not understand the issue. Everything has a spec. There is > >>> no need for an abrupt spec on any of the parameters. Humans typically > >>> don't respond to sub-millisecond stimuli other than perhaps light and > >>> then just barely. I guess sub-millisecond pressure changes can be > >>> noticed when they are in the form of explosions. > >> > >> Quoting such numbers indicates you clearly don't understand the issues. > >> > >> > >>> Why do people make silly statements about topics they don't actually > >>> know anything about? > >> > >> I built a commercial lung ventilator, a long time ago. How many have you > >> built? > >> > >> I suspect I have more of a clue about that than you. > > > > If you understood the issues you would not make the silly, technically vague, > > alarmist comments you have made here. The issues have to do with control > > theory, not medical. There is no medical requirement to drive pressure or > > air flow in microseconds. What was the step response of the ventilator you > > designed? I will have to say I'm impressed that one person can design such a > > complex device. There are many, many facets to it and typically it would > > involve many engineers. > > Wow. So many misconceptions in one paragraph. Let's keep it simple. > > 1) I made no such statement about driving/measuring in microseconds.
I did and then you replied that I didn't understand "the issues". That is the issue you initially responded to. I pointed out the difficulty of designing a controller to provide an adequate step response without overshoot can be mitigated by not feeding the controller an abrupt step function. From there on you disagreed with everything I wrote to clarify the issue. You are just wrong about this. It's time to stop back peddling and accept that.
> 2) I made no such statement about being the only person involved, > nor even the only company involved. > > You really ought to learn to read only that which is stated, > and not allow your preconceptions to blind you
Here is what you posted.... "I built a commercial lung ventilator, a long time ago." Where do you indicate you were not the only person involved? "I built" implies you and you alone. My response was a prod because I knew it was not you alone. Do I really need to explain the subtleties of the English language to you?
> For the record, the step is the event that a patient has > died or been resurrected. (There are many others, of course) > The event is instantaneous, of course, and flips operation to > *completely* different behavioural *modes*. Determining the > trigger conditions and ensuring appropriate future behaviour > is not trivial.
Now you are being silly. The step input is asking the machine to provide 0 pressure, then raising it to the set value for the next sample. Expecting it to respond without overshoot is a tall request when the thing being controlled (the system of machine and patient) varies from case to case. Asking an operator to tune the PID parameters is a bit much when it is not needed. The rise time and overshoot specs can be met more easily by feeding the control loop a set of steps of initially high, but sequentially decreasing value allowing the control loop to follow the request without excessive wind up of the I term and minimal overshoot for a wider range of patient parameters.
> It took 3 engineers in my company (RTOS infrastructure, > front panel, ventilator control), and several in another > company. The latter knew the ventilation requirements but not > how to design and implement them. > > I was the PM, and designed and implemented the ventilator > control.
Excellent. Then you should understand everything I've posted.
> > This is a perfect example of "if you're not part of the solution, you are > > part of the problem". Why are you going on about this? If you want to > > contribute, why not actually make a contribution. If you just want to rag on > > things, please go elsewhere. > > I'm going to decline in this case; it would be a waste > of my time in two ways: > > 1) I have tried to educate you before, and found it notably > difficult to get you to think away from your preconceptions. > (cf with the above) > > 2) this whole effort is doomed to failure, for the non-technical > reasons others have stated.
Obviously it is not a complete waste of your time or you would not be making these lengthy posts. I suspect it is more a matter of recognizing that your useful contributions are limited. So instead you are blustering. You could contribute to the project without ever dealing with me and my limited abilities to learn.
> > There are plenty of threads here where people are just ragging on one another > > ad infinitum. It would be nice to keep the technical threads free of that. > > Yes, we've noticed.
And yet you continue to use bandwidth to continue the conversation just so you can tell me how defective I am, but never actually making any technical points. None at all - in spite of your claims of superior knowledge. I still gain something from these discussions. They help me clarify my position by learning from your mistakes. Thank you. -- Rick C. ---- Get 1,000 miles of free Supercharging ---- Tesla referral code - https://ts.la/richard11209
Reply by Jan Panteltje August 21, 20202020-08-21
On a sunny day (Fri, 21 Aug 2020 08:36:27 -0700 (PDT)) it happened Ricketty C
<gnuarm.deletethisbit@gmail.com> wrote in
<8b0ef434-ffbe-48a1-95ab-d3999eb114e3o@googlegroups.com>:

>If you understood the issues you would not make the silly, technically vague, >alarmist comments you have made here. The issues have to do with control >theory, not medical. There is no medical requirement to drive pressure or >air flow in microseconds. What was the step response of the ventilator you >designed? I will have to say I'm impressed that one person can design such >a complex device. There are many, many facets to it and typically it would >involve many engineers. > >This is a perfect example of "if you're not part of the solution, you are part >of the problem". Why are you going on about this? If you want to contribute, >why not actually make a contribution. If you just want to rag on things, >please go elsewhere. > >There are plenty of threads here where people are just ragging on one another >ad infinitum. It would be nice to keep the technical threads free of that.
Rick stt Maybe YOU should simply build the thing, and not get lost in PID control theory. One can easily measure air pressure and adjust the speed of a motor drive, especially if it is a stepper, in milliseconds. Now all you need is knowledge about the human interface to make it follow a curve. No PID stuff, just millisecond by millisecond adjustment against a known curve. No long delays as in thermal heating and overshoot or big flywheels speeding up or whatever. Build something, test it on yourself. Best way to get feedback and FEEL where it needs improvement. You seem to think you are the only one in the universe who knows how to do things you have nothing yet, not even a prototype, math is useless in phantasy. There is an old joke here: How many <insert nationality here> guys does it take to screw in a light bulb? Answer: 5 one to hold the bulb, and 4 to turn the ceiling. I have been with a big company that actually now makes ventilators for the US, and the time from idea to production I was told there was 2 weeks. This thread has been going on and on, where is your prototype? No use trying to write code for a control system for a thing you do not even have. Untestable, Cool it man. :-)
Reply by Tom Gardner August 21, 20202020-08-21
On 21/08/20 16:36, Ricketty C wrote:
> On Friday, August 21, 2020 at 6:28:40 AM UTC-4, Tom Gardner wrote: >> On 21/08/20 10:57, Ricketty C wrote: >>> On Friday, August 21, 2020 at 5:36:58 AM UTC-4, Tom Gardner wrote: >>>> On 21/08/20 06:40, Ricketty C wrote: >>>>> On Thursday, August 20, 2020 at 9:22:01 PM UTC-4, George Herold >>>>> wrote: >>>>>> On Thursday, August 20, 2020 at 5:21:22 PM UTC-4, bitrex wrote: >>>>>>> On 8/19/2020 11:05 AM, George Herold wrote: >>>>>>>> On Tuesday, August 18, 2020 at 3:05:56 PM UTC-4, bitrex wrote: >>>>>>>>> On 8/17/2020 11:53 AM, George Herold wrote: >>>>>>>>>> On Sunday, August 16, 2020 at 11:14:22 AM UTC-4, >>>>>>>>>> jla...@highlandsniptechnology.com wrote: >>>>>>>>>>> On Sun, 16 Aug 2020 07:53:41 -0700 (PDT), Lasse Langwadt >>>>>>>>>>> Christensen <langwadt@fonz.dk> wrote: >>>>>>>>>>> >>>>>>>>>>>> s&#371;ndag den 16. august 2020 kl. 16.31.14 UTC+2 skrev >>>>>>>>>>>> Jan Panteltje: >>>>>>>>>>>>> On a sunny day (Sat, 15 Aug 2020 22:46:45 -0700 >>>>>>>>>>>>> (PDT)) it happened Ricketty C >>>>>>>>>>>>> <gnuarm.deletethisbit@gmail.com> wrote in >>>>>>>>>>>>> <d2d879c1-cf13-42f8-9727-8ef27dc2dc65o@googlegroups.com>: >>>>>>>>>>>>> >>>>>>>>>>>>>> >>>>>>>>>>>>>> >>>>>>>>>>>>> >> >>>>>>>>>>>>>
He shows the only difference between patient triggered and
>>>>>>>>>>>>>> machine triggered waveforms is the negative >>>>>>>>>>>>>> pressure from the patient trying to draw air in at >>>>>>>>>>>>>> the very start of the cycle. His diagrams are >>>>>>>>>>>>>> pretty poor with no registration between the >>>>>>>>>>>>>> various points on different parameters, but he gets >>>>>>>>>>>>>> across the main points. You can do a Google search >>>>>>>>>>>>>> to find other much better diagrams. I don't think >>>>>>>>>>>>>> there are any new concepts to an engineer. >>>>>>>>>>>>> >>>>>>>>>>>>> No experience with these things but from _my_ life I >>>>>>>>>>>>> know breathing is related to oxygen level in the >>>>>>>>>>>>> blood. >>>>>>>>>>>> >>>>>>>>>>>> not really, your breathing is mostly related to the >>>>>>>>>>>> amount of CO2 in your lungs that's why breathing >>>>>>>>>>>> something like pure nitrogen will kill you without you >>>>>>>>>>>> even noticing >>>>>>>>>>> >>>>>>>>>>> I wonder how many old ladies ricky's team plans to kill, >>>>>>>>>>> trying to learn PIDs and stuff. >>>>>>>>>> >>>>>>>>>> Do you know any good control 'theory/practice' books. I've >>>>>>>>>> got a few, but I tend to get a little lost in the Laplace >>>>>>>>>> transforms, And would love something with a more 'hands >>>>>>>>>> on' feel, an AoE type of book. >>>>>>>>>> >>>>>>>>>> Tim Wescott's book is fine. >>>>>>>>>> https://www.wescottdesign.com/actfes/actfes.html >>>>>>>>> >>>>>>>>> Would you enjoy this fine series from MIT on ordinary >>>>>>>>> differential equations including Laplace transforms: >>>>>>>>> >>>>>>>>> <https://www.youtube.com/watch?v=zvbdoSeGAgI> >>>>>>>>> >>>>>>>>> The whole lecture series is good. the Laplace transform (and >>>>>>>>> other integral transforms too) are, in general, tools for >>>>>>>>> solving differential equations. So a refresh on ODEs may be >>>>>>>>> helpful >>>>>>>> Yeah well I just replace 's' with 'i*w' (omega.. angular >>>>>>>> frequency) and Laplace transforms are fine. My problem is >>>>>>>> that it's easy to dig down into the math (algebra) and lose a >>>>>>>> sense of what is going on. I sorta need the math after I >>>>>>>> understand it. >>>>>>>> >>>>>>>> George H. >>>>>>> >>>>>>> Do you have a particular example of what in the process of >>>>>>> "understanding" is a sticking-point? >>>>>>> >>>>>> Not at the moment. I've done mostly thermal loops, which are easy >>>>>> (no thermal 'momentum/ inductance'). I guess the perennial >>>>>> question in a thermal loop is where to put the heater/ TEC / cooler >>>>>> (plant) and where to put the temperature sensor. >>>>> >>>>> Earlier it was pointed out that delays in the system can impact loop >>>>> stability. I believe thermal systems can have such delays, for >>>>> example, when the heater itself has significant thermal mass and the >>>>> object being heated also has thermal mass with some thermal impedance >>>>> between. >>>>> >>>>> Such a system can be stabilized by using multiple loops. A fast loop >>>>> to control the temperature of the first thermal mass and a second, >>>>> slower loop to adjust the set point of the first loop ultimately >>>>> managing the temperature of the second thermal mass. >>>>> >>>>> I suppose a single loop with a slow response would work, but I expect >>>>> it will require a slower response than the two loop design to deal >>>>> with integrator wind up because the inner loop would allow the set >>>>> point to ramp up more quickly without ramping up the outer loop >>>>> integrator. Yes, no? >>>>> >>>>> Today in the conference call I explained the idea of reducing the >>>>> overshoot by instead of limiting the slew rate of the PID controller, >>>>> not driving it with an abrupt step function. Rather a slope can be >>>>> used appropriate for the desired ramp up of the controlled variable. >>>>> Rather than focus on making the controller manage the rate, give it >>>>> the rate it should follow. >>>> >>>> There will be step changes when ventilating a patient. Obvious ones >>>> are when the patient stops or starts trying to breath. >>>> >>>> Gently reacting to a patient that no longer inspires and expires is >>>> likely to lead to a long-lasting expiration. >>>> >>>> Ditto inflating a patient that is trying to take control of their >>>> life. >>> >>> You seem to not understand the issue. Everything has a spec. There is >>> no need for an abrupt spec on any of the parameters. Humans typically >>> don't respond to sub-millisecond stimuli other than perhaps light and >>> then just barely. I guess sub-millisecond pressure changes can be >>> noticed when they are in the form of explosions. >> >> Quoting such numbers indicates you clearly don't understand the issues. >> >> >>> Why do people make silly statements about topics they don't actually >>> know anything about? >> >> I built a commercial lung ventilator, a long time ago. How many have you >> built? >> >> I suspect I have more of a clue about that than you. > > If you understood the issues you would not make the silly, technically vague, > alarmist comments you have made here. The issues have to do with control > theory, not medical. There is no medical requirement to drive pressure or > air flow in microseconds. What was the step response of the ventilator you > designed? I will have to say I'm impressed that one person can design such a > complex device. There are many, many facets to it and typically it would > involve many engineers.
Wow. So many misconceptions in one paragraph. Let's keep it simple. 1) I made no such statement about driving/measuring in microseconds. 2) I made no such statement about being the only person involved, nor even the only company involved. You really ought to learn to read only that which is stated, and not allow your preconceptions to blind you For the record, the step is the event that a patient has died or been resurrected. (There are many others, of course) The event is instantaneous, of course, and flips operation to *completely* different behavioural *modes*. Determining the trigger conditions and ensuring appropriate future behaviour is not trivial. It took 3 engineers in my company (RTOS infrastructure, front panel, ventilator control), and several in another company. The latter knew the ventilation requirements but not how to design and implement them. I was the PM, and designed and implemented the ventilator control.
> This is a perfect example of "if you're not part of the solution, you are > part of the problem". Why are you going on about this? If you want to > contribute, why not actually make a contribution. If you just want to rag on > things, please go elsewhere.
I'm going to decline in this case; it would be a waste of my time in two ways: 1) I have tried to educate you before, and found it notably difficult to get you to think away from your preconceptions. (cf with the above) 2) this whole effort is doomed to failure, for the non-technical reasons others have stated.
> There are plenty of threads here where people are just ragging on one another > ad infinitum. It would be nice to keep the technical threads free of that.
Yes, we've noticed.
Reply by Ricketty C August 21, 20202020-08-21
On Friday, August 21, 2020 at 6:28:40 AM UTC-4, Tom Gardner wrote:
> On 21/08/20 10:57, Ricketty C wrote: > > On Friday, August 21, 2020 at 5:36:58 AM UTC-4, Tom Gardner wrote: > >> On 21/08/20 06:40, Ricketty C wrote: > >>> On Thursday, August 20, 2020 at 9:22:01 PM UTC-4, George Herold wrote: > >>>> On Thursday, August 20, 2020 at 5:21:22 PM UTC-4, bitrex wrote: > >>>>> On 8/19/2020 11:05 AM, George Herold wrote: > >>>>>> On Tuesday, August 18, 2020 at 3:05:56 PM UTC-4, bitrex wrote: > >>>>>>> On 8/17/2020 11:53 AM, George Herold wrote: > >>>>>>>> On Sunday, August 16, 2020 at 11:14:22 AM UTC-4, > >>>>>>>> jla...@highlandsniptechnology.com wrote: > >>>>>>>>> On Sun, 16 Aug 2020 07:53:41 -0700 (PDT), Lasse Langwadt > >>>>>>>>> Christensen <langwadt@fonz.dk> wrote: > >>>>>>>>> > >>>>>>>>>> s&#371;ndag den 16. august 2020 kl. 16.31.14 UTC+2 skrev Jan > >>>>>>>>>> Panteltje: > >>>>>>>>>>> On a sunny day (Sat, 15 Aug 2020 22:46:45 -0700 (PDT)) > >>>>>>>>>>> it happened Ricketty C <gnuarm.deletethisbit@gmail.com> > >>>>>>>>>>> wrote in > >>>>>>>>>>> <d2d879c1-cf13-42f8-9727-8ef27dc2dc65o@googlegroups.com>: > >>>>>>>>>>> > >>>>>>>>>>>> > >>>>>>>>>>>> > >>>>>>>>>>> > He shows the only difference between patient triggered and > >>>>>>>>>>>> machine triggered waveforms is the negative pressure > >>>>>>>>>>>> from the patient trying to draw air in at the very > >>>>>>>>>>>> start of the cycle. His diagrams are pretty poor with > >>>>>>>>>>>> no registration between the various points on different > >>>>>>>>>>>> parameters, but he gets across the main points. You > >>>>>>>>>>>> can do a Google search to find other much better > >>>>>>>>>>>> diagrams. I don't think there are any new concepts to > >>>>>>>>>>>> an engineer. > >>>>>>>>>>> > >>>>>>>>>>> No experience with these things but from _my_ life I > >>>>>>>>>>> know breathing is related to oxygen level in the blood. > >>>>>>>>>> > >>>>>>>>>> not really, your breathing is mostly related to the amount > >>>>>>>>>> of CO2 in your lungs that's why breathing something like > >>>>>>>>>> pure nitrogen will kill you without you even noticing > >>>>>>>>> > >>>>>>>>> I wonder how many old ladies ricky's team plans to kill, > >>>>>>>>> trying to learn PIDs and stuff. > >>>>>>>> > >>>>>>>> Do you know any good control 'theory/practice' books. I've got > >>>>>>>> a few, but I tend to get a little lost in the Laplace > >>>>>>>> transforms, And would love something with a more 'hands on' > >>>>>>>> feel, an AoE type of book. > >>>>>>>> > >>>>>>>> Tim Wescott's book is fine. > >>>>>>>> https://www.wescottdesign.com/actfes/actfes.html > >>>>>>> > >>>>>>> Would you enjoy this fine series from MIT on ordinary > >>>>>>> differential equations including Laplace transforms: > >>>>>>> > >>>>>>> <https://www.youtube.com/watch?v=zvbdoSeGAgI> > >>>>>>> > >>>>>>> The whole lecture series is good. the Laplace transform (and > >>>>>>> other integral transforms too) are, in general, tools for > >>>>>>> solving differential equations. So a refresh on ODEs may be > >>>>>>> helpful > >>>>>> Yeah well I just replace 's' with 'i*w' (omega.. angular > >>>>>> frequency) and Laplace transforms are fine. My problem is that > >>>>>> it's easy to dig down into the math (algebra) and lose a sense of > >>>>>> what is going on. I sorta need the math after I understand it. > >>>>>> > >>>>>> George H. > >>>>> > >>>>> Do you have a particular example of what in the process of > >>>>> "understanding" is a sticking-point? > >>>>> > >>>> Not at the moment. I've done mostly thermal loops, which are easy (no > >>>> thermal 'momentum/ inductance'). I guess the perennial question in a > >>>> thermal loop is where to put the heater/ TEC / cooler (plant) and where > >>>> to put the temperature sensor. > >>> > >>> Earlier it was pointed out that delays in the system can impact loop > >>> stability. I believe thermal systems can have such delays, for example, > >>> when the heater itself has significant thermal mass and the object being > >>> heated also has thermal mass with some thermal impedance between. > >>> > >>> Such a system can be stabilized by using multiple loops. A fast loop to > >>> control the temperature of the first thermal mass and a second, slower > >>> loop to adjust the set point of the first loop ultimately managing the > >>> temperature of the second thermal mass. > >>> > >>> I suppose a single loop with a slow response would work, but I expect it > >>> will require a slower response than the two loop design to deal with > >>> integrator wind up because the inner loop would allow the set point to > >>> ramp up more quickly without ramping up the outer loop integrator. Yes, > >>> no? > >>> > >>> Today in the conference call I explained the idea of reducing the > >>> overshoot by instead of limiting the slew rate of the PID controller, not > >>> driving it with an abrupt step function. Rather a slope can be used > >>> appropriate for the desired ramp up of the controlled variable. Rather > >>> than focus on making the controller manage the rate, give it the rate it > >>> should follow. > >> > >> There will be step changes when ventilating a patient. Obvious ones are > >> when the patient stops or starts trying to breath. > >> > >> Gently reacting to a patient that no longer inspires and expires is likely > >> to lead to a long-lasting expiration. > >> > >> Ditto inflating a patient that is trying to take control of their life. > > > > You seem to not understand the issue. Everything has a spec. There is no > > need for an abrupt spec on any of the parameters. Humans typically don't > > respond to sub-millisecond stimuli other than perhaps light and then just > > barely. I guess sub-millisecond pressure changes can be noticed when they > > are in the form of explosions. > > Quoting such numbers indicates you clearly don't understand the issues. > > > > Why do people make silly statements about topics they don't actually know > > anything about? > > I built a commercial lung ventilator, a long time ago. How many have you built? > > I suspect I have more of a clue about that than you.
If you understood the issues you would not make the silly, technically vague, alarmist comments you have made here. The issues have to do with control theory, not medical. There is no medical requirement to drive pressure or air flow in microseconds. What was the step response of the ventilator you designed? I will have to say I'm impressed that one person can design such a complex device. There are many, many facets to it and typically it would involve many engineers. This is a perfect example of "if you're not part of the solution, you are part of the problem". Why are you going on about this? If you want to contribute, why not actually make a contribution. If you just want to rag on things, please go elsewhere. There are plenty of threads here where people are just ragging on one another ad infinitum. It would be nice to keep the technical threads free of that. -- Rick C. +++ Get 1,000 miles of free Supercharging +++ Tesla referral code - https://ts.la/richard11209
Reply by Tom Gardner August 21, 20202020-08-21
On 21/08/20 10:57, Ricketty C wrote:
> On Friday, August 21, 2020 at 5:36:58 AM UTC-4, Tom Gardner wrote: >> On 21/08/20 06:40, Ricketty C wrote: >>> On Thursday, August 20, 2020 at 9:22:01 PM UTC-4, George Herold wrote: >>>> On Thursday, August 20, 2020 at 5:21:22 PM UTC-4, bitrex wrote: >>>>> On 8/19/2020 11:05 AM, George Herold wrote: >>>>>> On Tuesday, August 18, 2020 at 3:05:56 PM UTC-4, bitrex wrote: >>>>>>> On 8/17/2020 11:53 AM, George Herold wrote: >>>>>>>> On Sunday, August 16, 2020 at 11:14:22 AM UTC-4, >>>>>>>> jla...@highlandsniptechnology.com wrote: >>>>>>>>> On Sun, 16 Aug 2020 07:53:41 -0700 (PDT), Lasse Langwadt >>>>>>>>> Christensen <langwadt@fonz.dk> wrote: >>>>>>>>> >>>>>>>>>> s&#371;ndag den 16. august 2020 kl. 16.31.14 UTC+2 skrev Jan >>>>>>>>>> Panteltje: >>>>>>>>>>> On a sunny day (Sat, 15 Aug 2020 22:46:45 -0700 (PDT)) >>>>>>>>>>> it happened Ricketty C <gnuarm.deletethisbit@gmail.com> >>>>>>>>>>> wrote in >>>>>>>>>>> <d2d879c1-cf13-42f8-9727-8ef27dc2dc65o@googlegroups.com>: >>>>>>>>>>> >>>>>>>>>>>> >>>>>>>>>>>> >>>>>>>>>>>
He shows the only difference between patient triggered and
>>>>>>>>>>>> machine triggered waveforms is the negative pressure >>>>>>>>>>>> from the patient trying to draw air in at the very >>>>>>>>>>>> start of the cycle. His diagrams are pretty poor with >>>>>>>>>>>> no registration between the various points on different >>>>>>>>>>>> parameters, but he gets across the main points. You >>>>>>>>>>>> can do a Google search to find other much better >>>>>>>>>>>> diagrams. I don't think there are any new concepts to >>>>>>>>>>>> an engineer. >>>>>>>>>>> >>>>>>>>>>> No experience with these things but from _my_ life I >>>>>>>>>>> know breathing is related to oxygen level in the blood. >>>>>>>>>> >>>>>>>>>> not really, your breathing is mostly related to the amount >>>>>>>>>> of CO2 in your lungs that's why breathing something like >>>>>>>>>> pure nitrogen will kill you without you even noticing >>>>>>>>> >>>>>>>>> I wonder how many old ladies ricky's team plans to kill, >>>>>>>>> trying to learn PIDs and stuff. >>>>>>>> >>>>>>>> Do you know any good control 'theory/practice' books. I've got >>>>>>>> a few, but I tend to get a little lost in the Laplace >>>>>>>> transforms, And would love something with a more 'hands on' >>>>>>>> feel, an AoE type of book. >>>>>>>> >>>>>>>> Tim Wescott's book is fine. >>>>>>>> https://www.wescottdesign.com/actfes/actfes.html >>>>>>> >>>>>>> Would you enjoy this fine series from MIT on ordinary >>>>>>> differential equations including Laplace transforms: >>>>>>> >>>>>>> <https://www.youtube.com/watch?v=zvbdoSeGAgI> >>>>>>> >>>>>>> The whole lecture series is good. the Laplace transform (and >>>>>>> other integral transforms too) are, in general, tools for >>>>>>> solving differential equations. So a refresh on ODEs may be >>>>>>> helpful >>>>>> Yeah well I just replace 's' with 'i*w' (omega.. angular >>>>>> frequency) and Laplace transforms are fine. My problem is that >>>>>> it's easy to dig down into the math (algebra) and lose a sense of >>>>>> what is going on. I sorta need the math after I understand it. >>>>>> >>>>>> George H. >>>>> >>>>> Do you have a particular example of what in the process of >>>>> "understanding" is a sticking-point? >>>>> >>>> Not at the moment. I've done mostly thermal loops, which are easy (no >>>> thermal 'momentum/ inductance'). I guess the perennial question in a >>>> thermal loop is where to put the heater/ TEC / cooler (plant) and where >>>> to put the temperature sensor. >>> >>> Earlier it was pointed out that delays in the system can impact loop >>> stability. I believe thermal systems can have such delays, for example, >>> when the heater itself has significant thermal mass and the object being >>> heated also has thermal mass with some thermal impedance between. >>> >>> Such a system can be stabilized by using multiple loops. A fast loop to >>> control the temperature of the first thermal mass and a second, slower >>> loop to adjust the set point of the first loop ultimately managing the >>> temperature of the second thermal mass. >>> >>> I suppose a single loop with a slow response would work, but I expect it >>> will require a slower response than the two loop design to deal with >>> integrator wind up because the inner loop would allow the set point to >>> ramp up more quickly without ramping up the outer loop integrator. Yes, >>> no? >>> >>> Today in the conference call I explained the idea of reducing the >>> overshoot by instead of limiting the slew rate of the PID controller, not >>> driving it with an abrupt step function. Rather a slope can be used >>> appropriate for the desired ramp up of the controlled variable. Rather >>> than focus on making the controller manage the rate, give it the rate it >>> should follow. >> >> There will be step changes when ventilating a patient. Obvious ones are >> when the patient stops or starts trying to breath. >> >> Gently reacting to a patient that no longer inspires and expires is likely >> to lead to a long-lasting expiration. >> >> Ditto inflating a patient that is trying to take control of their life. > > You seem to not understand the issue. Everything has a spec. There is no > need for an abrupt spec on any of the parameters. Humans typically don't > respond to sub-millisecond stimuli other than perhaps light and then just > barely. I guess sub-millisecond pressure changes can be noticed when they > are in the form of explosions.
Quoting such numbers indicates you clearly don't understand the issues.
> Why do people make silly statements about topics they don't actually know > anything about?
I built a commercial lung ventilator, a long time ago. How many have you built? I suspect I have more of a clue about that than you.
Reply by Ricketty C August 21, 20202020-08-21
On Friday, August 21, 2020 at 5:36:58 AM UTC-4, Tom Gardner wrote:
> On 21/08/20 06:40, Ricketty C wrote: > > On Thursday, August 20, 2020 at 9:22:01 PM UTC-4, George Herold wrote: > >> On Thursday, August 20, 2020 at 5:21:22 PM UTC-4, bitrex wrote: > >>> On 8/19/2020 11:05 AM, George Herold wrote: > >>>> On Tuesday, August 18, 2020 at 3:05:56 PM UTC-4, bitrex wrote: > >>>>> On 8/17/2020 11:53 AM, George Herold wrote: > >>>>>> On Sunday, August 16, 2020 at 11:14:22 AM UTC-4, > >>>>>> jla...@highlandsniptechnology.com wrote: > >>>>>>> On Sun, 16 Aug 2020 07:53:41 -0700 (PDT), Lasse Langwadt > >>>>>>> Christensen <langwadt@fonz.dk> wrote: > >>>>>>> > >>>>>>>> s&#371;ndag den 16. august 2020 kl. 16.31.14 UTC+2 skrev Jan > >>>>>>>> Panteltje: > >>>>>>>>> On a sunny day (Sat, 15 Aug 2020 22:46:45 -0700 (PDT)) it > >>>>>>>>> happened Ricketty C <gnuarm.deletethisbit@gmail.com> wrote > >>>>>>>>> in <d2d879c1-cf13-42f8-9727-8ef27dc2dc65o@googlegroups.com>: > >>>>>>>>> > >>>>>>>>>> > >>>>>>>>>> He shows the only difference between patient triggered and > >>>>>>>>>> machine triggered waveforms is the negative pressure from > >>>>>>>>>> the patient trying to draw air in at the very start of the > >>>>>>>>>> cycle. His diagrams are pretty poor with no registration > >>>>>>>>>> between the various points on different parameters, but he > >>>>>>>>>> gets across the main points. You can do a Google search to > >>>>>>>>>> find other much better diagrams. I don't think there are > >>>>>>>>>> any new concepts to an engineer. > >>>>>>>>> > >>>>>>>>> No experience with these things but from _my_ life I know > >>>>>>>>> breathing is related to oxygen level in the blood. > >>>>>>>> > >>>>>>>> not really, your breathing is mostly related to the amount of > >>>>>>>> CO2 in your lungs that's why breathing something like pure > >>>>>>>> nitrogen will kill you without you even noticing > >>>>>>> > >>>>>>> I wonder how many old ladies ricky's team plans to kill, trying > >>>>>>> to learn PIDs and stuff. > >>>>>> > >>>>>> Do you know any good control 'theory/practice' books. I've got a > >>>>>> few, but I tend to get a little lost in the Laplace transforms, And > >>>>>> would love something with a more 'hands on' feel, an AoE type of > >>>>>> book. > >>>>>> > >>>>>> Tim Wescott's book is fine. > >>>>>> https://www.wescottdesign.com/actfes/actfes.html > >>>>> > >>>>> Would you enjoy this fine series from MIT on ordinary differential > >>>>> equations including Laplace transforms: > >>>>> > >>>>> <https://www.youtube.com/watch?v=zvbdoSeGAgI> > >>>>> > >>>>> The whole lecture series is good. the Laplace transform (and other > >>>>> integral transforms too) are, in general, tools for solving > >>>>> differential equations. So a refresh on ODEs may be helpful > >>>> Yeah well I just replace 's' with 'i*w' (omega.. angular frequency) > >>>> and Laplace transforms are fine. My problem is that it's easy to dig > >>>> down into the math (algebra) and lose a sense of what is going on. I > >>>> sorta need the math after I understand it. > >>>> > >>>> George H. > >>> > >>> Do you have a particular example of what in the process of > >>> "understanding" is a sticking-point? > >>> > >> Not at the moment. I've done mostly thermal loops, which are easy (no > >> thermal 'momentum/ inductance'). I guess the perennial question in a > >> thermal loop is where to put the heater/ TEC / cooler (plant) and where to > >> put the temperature sensor. > > > > Earlier it was pointed out that delays in the system can impact loop > > stability. I believe thermal systems can have such delays, for example, when > > the heater itself has significant thermal mass and the object being heated > > also has thermal mass with some thermal impedance between. > > > > Such a system can be stabilized by using multiple loops. A fast loop to > > control the temperature of the first thermal mass and a second, slower loop > > to adjust the set point of the first loop ultimately managing the temperature > > of the second thermal mass. > > > > I suppose a single loop with a slow response would work, but I expect it will > > require a slower response than the two loop design to deal with integrator > > wind up because the inner loop would allow the set point to ramp up more > > quickly without ramping up the outer loop integrator. Yes, no? > > > > Today in the conference call I explained the idea of reducing the overshoot > > by instead of limiting the slew rate of the PID controller, not driving it > > with an abrupt step function. Rather a slope can be used appropriate for the > > desired ramp up of the controlled variable. Rather than focus on making the > > controller manage the rate, give it the rate it should follow. > > There will be step changes when ventilating a patient. > Obvious ones are when the patient stops or starts trying > to breath. > > Gently reacting to a patient that no longer inspires and > expires is likely to lead to a long-lasting expiration. > > Ditto inflating a patient that is trying to take control > of their life.
You seem to not understand the issue. Everything has a spec. There is no need for an abrupt spec on any of the parameters. Humans typically don't respond to sub-millisecond stimuli other than perhaps light and then just barely. I guess sub-millisecond pressure changes can be noticed when they are in the form of explosions. Why do people make silly statements about topics they don't actually know anything about? -- Rick C. ++- Get 1,000 miles of free Supercharging ++- Tesla referral code - https://ts.la/richard11209
Reply by Tom Gardner August 21, 20202020-08-21
On 21/08/20 06:40, Ricketty C wrote:
> On Thursday, August 20, 2020 at 9:22:01 PM UTC-4, George Herold wrote: >> On Thursday, August 20, 2020 at 5:21:22 PM UTC-4, bitrex wrote: >>> On 8/19/2020 11:05 AM, George Herold wrote: >>>> On Tuesday, August 18, 2020 at 3:05:56 PM UTC-4, bitrex wrote: >>>>> On 8/17/2020 11:53 AM, George Herold wrote: >>>>>> On Sunday, August 16, 2020 at 11:14:22 AM UTC-4, >>>>>> jla...@highlandsniptechnology.com wrote: >>>>>>> On Sun, 16 Aug 2020 07:53:41 -0700 (PDT), Lasse Langwadt >>>>>>> Christensen <langwadt@fonz.dk> wrote: >>>>>>> >>>>>>>> s&#371;ndag den 16. august 2020 kl. 16.31.14 UTC+2 skrev Jan >>>>>>>> Panteltje: >>>>>>>>> On a sunny day (Sat, 15 Aug 2020 22:46:45 -0700 (PDT)) it >>>>>>>>> happened Ricketty C <gnuarm.deletethisbit@gmail.com> wrote >>>>>>>>> in <d2d879c1-cf13-42f8-9727-8ef27dc2dc65o@googlegroups.com>: >>>>>>>>> >>>>>>>>>> >>>>>>>>>> He shows the only difference between patient triggered and >>>>>>>>>> machine triggered waveforms is the negative pressure from >>>>>>>>>> the patient trying to draw air in at the very start of the >>>>>>>>>> cycle. His diagrams are pretty poor with no registration >>>>>>>>>> between the various points on different parameters, but he >>>>>>>>>> gets across the main points. You can do a Google search to >>>>>>>>>> find other much better diagrams. I don't think there are >>>>>>>>>> any new concepts to an engineer. >>>>>>>>> >>>>>>>>> No experience with these things but from _my_ life I know >>>>>>>>> breathing is related to oxygen level in the blood. >>>>>>>> >>>>>>>> not really, your breathing is mostly related to the amount of >>>>>>>> CO2 in your lungs that's why breathing something like pure >>>>>>>> nitrogen will kill you without you even noticing >>>>>>> >>>>>>> I wonder how many old ladies ricky's team plans to kill, trying >>>>>>> to learn PIDs and stuff. >>>>>> >>>>>> Do you know any good control 'theory/practice' books. I've got a >>>>>> few, but I tend to get a little lost in the Laplace transforms, And >>>>>> would love something with a more 'hands on' feel, an AoE type of >>>>>> book. >>>>>> >>>>>> Tim Wescott's book is fine. >>>>>> https://www.wescottdesign.com/actfes/actfes.html >>>>> >>>>> Would you enjoy this fine series from MIT on ordinary differential >>>>> equations including Laplace transforms: >>>>> >>>>> <https://www.youtube.com/watch?v=zvbdoSeGAgI> >>>>> >>>>> The whole lecture series is good. the Laplace transform (and other >>>>> integral transforms too) are, in general, tools for solving >>>>> differential equations. So a refresh on ODEs may be helpful >>>> Yeah well I just replace 's' with 'i*w' (omega.. angular frequency) >>>> and Laplace transforms are fine. My problem is that it's easy to dig >>>> down into the math (algebra) and lose a sense of what is going on. I >>>> sorta need the math after I understand it. >>>> >>>> George H. >>> >>> Do you have a particular example of what in the process of >>> "understanding" is a sticking-point? >>> >> Not at the moment. I've done mostly thermal loops, which are easy (no >> thermal 'momentum/ inductance'). I guess the perennial question in a >> thermal loop is where to put the heater/ TEC / cooler (plant) and where to >> put the temperature sensor. > > Earlier it was pointed out that delays in the system can impact loop > stability. I believe thermal systems can have such delays, for example, when > the heater itself has significant thermal mass and the object being heated > also has thermal mass with some thermal impedance between. > > Such a system can be stabilized by using multiple loops. A fast loop to > control the temperature of the first thermal mass and a second, slower loop > to adjust the set point of the first loop ultimately managing the temperature > of the second thermal mass. > > I suppose a single loop with a slow response would work, but I expect it will > require a slower response than the two loop design to deal with integrator > wind up because the inner loop would allow the set point to ramp up more > quickly without ramping up the outer loop integrator. Yes, no? > > Today in the conference call I explained the idea of reducing the overshoot > by instead of limiting the slew rate of the PID controller, not driving it > with an abrupt step function. Rather a slope can be used appropriate for the > desired ramp up of the controlled variable. Rather than focus on making the > controller manage the rate, give it the rate it should follow.
There will be step changes when ventilating a patient. Obvious ones are when the patient stops or starts trying to breath. Gently reacting to a patient that no longer inspires and expires is likely to lead to a long-lasting expiration. Ditto inflating a patient that is trying to take control of their life.