PD2 Feedforward Control for Process Transfer Function with Damping = 0



As usually you didn't answer my question about how you figure the damping = 0?

Jan:
Cited
Cited
Cited http://home.arcor.de/janch/janch/_control/20070608-pd2 (pid)d0/ d=0.001 (now 6 pages of information)
Three times in text plus once as plot (~0)! Makes 4 times. Please, ask not any more for the damping value. It was known since my first post (page 1).
Instead I am interested in seeing your PID result I have asked for. If it looks worse don't feel ashamed. It can't be better.
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Regards/Gre http://home.arcor.de/janch/janch/menue.htm
Jan C. Hoffmann eMail aktuell: snipped-for-privacy@nospam.arcornews.de
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: > Microsoft-kompatibel/optimiert fr IE7+OE7 : : : : As usually you didn't answer my question about how you figure the : damping = 0? : : >>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>> : : Jan: : : Cited : > Page 1: Process transfer function with 'damping ~ 0' : : Cited : > A1 = 6.324E-05 : : Cited : http://home.arcor.de/janch/janch/_control/20070608-pd2 (pid)d0/ : d=0.001 (now 6 pages of information)
d=0.001 is better. It depends on your definition of close to 0 doesn't it? At least now I know you know what you are taking about when it comes to damping factors and aren't throwing out numbers. Showing your work would have answered this immediately.
: Instead I am interested in seeing your PID result I have asked for. If it : looks worse don't feel ashamed. It can't be better.
You just don't get it do you?. I have all of these problems worked out symbollically. I can just look at the response you have and pick a desired response that will be faster or smoother or better by any definition you like and the symbolic formulas will calculate gains to give me that response. It is easy on Mathcad or some other symbolic math package when you don't have to worry about reality. So what is you want or are trying to prove? If you want to win some contest you won't. If you want to know how to calculate gains I have shown you how I calcualate gains symbolically and using Ackermann's equation in previous threads but you have ignored it. You should know that what I have shown in the past is just two methods and there are others.
Peter Nachtwey
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Peter, please read my work again: 2007/June/08 http://home.arcor.de/janch/janch/_control/20070608-pd2 (pid)d0/ The task was clear.

Show us a hardcopy with few points calculated or a plot. I already compared PID and PD2(PID). Result: PD2(PID) is better.

I will know which method is better. I truly couldn't find that just PID is better. I had had a contest already with me, i.e. PID against PD2(PID). By the way have you also tried controlling with disturbance.

Sorry Peter, do relate to the task. You know damping is almost zero. It's a bit more difficult.
Actual task to discuss: http://home.arcor.de/janch/janch/_control/20070608-pd2 (pid)d0/
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Regards/Gre http://home.arcor.de/janch/janch/menue.htm
Jan C. Hoffmann eMail aktuell: snipped-for-privacy@nospam.arcornews.de
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: Peter, please read my work again: 2007/June/08 : http://home.arcor.de/janch/janch/_control/20070608-pd2 (pid)d0/ : The task was clear.
: : > : Instead I am interested in seeing your PID result I have asked for. If : > it Why should I? You haven't shown how you calculate your PID gains once. I have shown how I calculate gains twice, once symbolically and once using Ackermann's method. In both cases I can just increase the desired response until it beats yours. This is easy when I don't need to worry about reality.
BTW, you don't know how funny your PID vs PD2(PID) comparison is. Do you play chess with yourself too? You can prove any opening is better than another because your personal biases will get in the way.
Peter Nachtwey
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Ok, please give us the K_PID, T_I, and T_D you symbolically found as best.
Refer only to this thread: http://home.arcor.de/janch/janch/_control/20070608-pd2 (pid)d0/
I show you the plots/comparisons.
Note You should know that any plot is a result of the formulae you find in page 3.
--
Regards/Gre http://home.arcor.de/janch/janch/menue.htm
Jan C. Hoffmann eMail aktuell: snipped-for-privacy@nospam.arcornews.de
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Newsbeitrag

If my responses are better than yours will you stop posting irrelevant links to your web pages? Those web pages that are relevant should be proof read by someone else before you post a link to it. Well?
Peter Nachtwey
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Peter, why should I stop post calculated data? Anyone can decide to read or to skip my websites. If you won't give me your K_PID, T_I and T_D, please PLONK me.
Thanks in advance.
PS: If anyone else asks me for provable data I will set the data into a website. Please without conditions! Just ask for them.
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Regards/Gre http://home.arcor.de/janch/janch/menue.htm
Jan C. Hoffmann eMail aktuell: snipped-for-privacy@nospam.arcornews.de
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snipped-for-privacy@gmail.com wrote:

Honestly, Peter, I think that you are perhaps pushing this too far. The internet is full of texts of disputable validity. You cannot change it. You seem to underestimate the readers, though, be they even control engineering newbies. Relax, Peter. If some newbie gets allured by JCH's confusing texts, it only shows that they did not study hard and were not critical enough. That is life...:-)
Zdenek Hurak
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Why is it that I can leave JCH's post alone for a couple days and no one can find the flaws? I think he is fooling more than the rookies. You and I may be very familiar with differential equations but I bet most that visit this newsgroup are not. I think JCH has math skills but doesn't know how to use them. What JCH is proposing will not come close to working in reality. JCH's examples are that bad. I will wait one more day. What is wrong with JCH's laser measurement system? Is a natural frequency of about 5 Hz realistic or is 0.5 Hz a more realistic example? Us JCH's system controllable at 5 Hz. If the natural frequency in JCH's examples are reduced by a factor of 10 what does that do to the gains? What does that do to the control output?
Peter Nachtwey
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wrote:

I didn't specify the time scale. It can be milliseconds, seconds, minutes, houres, etc. It can also be 3 seconds, 1/1.1223 minutes.
The distance could be inches, meters, kilometers, etc. Can you find such specifications?
Look at http://home.arcor.de/janch/janch/_control/20070613-pd2 (pid)z1z2/
Tell me where you find a dimension (unit). I wouldn't mind if using 1 pet for 3.5564 seconds and 1 tim for 12.4325 inches. Then read distance in tims, velocity 1 tim/pet and acceleration in tims/pet^2.
Example 1 tim/pet^2 = 12.4325inches/(3.5564 seconds)^2 0.982963212809897inches/second
It's convenient to me to tackle such problems as I do. Just the basis must be known.
ABOUT GAINS: I refer for definitions to page 1
e = u - v1 v2_PID = K_PID * (e + 1/T_i * Integral e*dt + T_D*e')
If u=const then e' = - v1'. But u is not constant!
v1 range is 0.2...1 (0.80%) and v2 range is 0.2...1 (0.80%). If an optimization procedure calculates gain K_PID = 1.65 on the basis 0.2...1 then K_PID = 100%/60.6%
The MAX. controller value can be 100% or 1 for internal value. The MIN. controller value can be 0% or 0.2 for internal value.
If distance transmitter range is 0 to 10 meters then 0.2...1 equals e.g. 4...20 mA and the P-Band of controller is 6.06 meter or 60.6%.
If controller output is moved 10% then 6.06% process value is moved/changed (not regarding integral and derivative action).
Basically one cannot ignore the life point (0.2, 4mA, 2V etc.). You can get into trouble ignoring that in simulating and in practice. Ranges e.g. -10...0...+10V should be transformed e.g. into 0.2...1 or 4...20mA, etc. That is industrial standard and should be used if algebraically processing signals or computer values.
--
Regards/Gre http://home.arcor.de/janch/janch/menue.htm
Jan C. Hoffmann eMail aktuell: snipped-for-privacy@nospam.arcornews.de
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wrote:

Sorry, should be

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Regards/Gre http://home.arcor.de/janch/janch/menue.htm
Jan C. Hoffmann eMail aktuell: snipped-for-privacy@nospam.arcornews.de
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: Sorry, should be : > 0.982963212809897inches/second^2
That's OK. I think everyone is beyond caring now.
Peter Nachtwey
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Yes, I know. You find many faults where no fault can be found. I think you are a little bit exaggerating. At least my solver works.
SOLVER TEST
Task and solution: http://ftp.cwi.nl/IVPtestset/report/hires.pdf
My solver test for comparing: http://home.arcor.de/janch/janch/_news/20070617-solvertest /
I was interested. Don't waste your time my solver is ok.
--
Regards/Gre http://home.arcor.de/janch/janch/menue.htm
Jan C. Hoffmann eMail aktuell: snipped-for-privacy@nospam.arcornews.de
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snipped-for-privacy@gmail.com wrote:
...

Because most people just don't read them any more?
Jerry
--
Engineering is the art of making what you want from things you can get.
¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯
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snipped-for-privacy@gmail.com wrote:

With all due respect to JCH's desire to improve himself and the world, because what he's saying is obviously poorly presented and often wrong. _Anything_ said on the internet or Usenet should be taken with a huge grain of salt, so there's no reason to flog the subject if a presenter won't listen.

Frankly, I just don't see myself as having the responsibility for chasing after all the people giving bad advise on Usenet. If I see someone giving advise contrary to what I would do in response to a question I'll respond, and let the original poster decide which answer to believe.
But someone who's just spontaneously posting cracked "tutorials" usually doesn't yield a very high effect:effort ratio, as you're finding. Since I have faith that one doesn't need to know differential calculus to recognize BS when one sees it, I don't feel a driving need to respond to his sort of posts.
It would be different if he posted his stuff, asked "oh experienced folk, what can you tell me about what I've done", then actually _listened_ to the responses (other than to argue). But since his receiver is broken, I see no reason to transmit.
--

Tim Wescott
Wescott Design Services
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What is the relationship of k1 to k2?
Peter Nachtwey
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What is the relationship of k1 to k2?

Jan:
http://home.arcor.de/janch/janch/_control/20070608-pd2 (pid)d0/ Exact definitions for K1 and K2 in page 3
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Regards/Gre http://home.arcor.de/janch/janch/menue.htm
Jan C. Hoffmann eMail aktuell: snipped-for-privacy@nospam.arcornews.de
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: : : : What is the relationship of k1 to k2? : : : >>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>> : : Jan: : : http://home.arcor.de/janch/janch/_control/20070608-pd2 (pid)d0/ : Exact definitions for K1 and K2 in page 3 : I see no definitions there.
On this page http://home.arcor.de/janch/janch/_control/20070606-pd3 (pid)z/ I see a definition of k1=k2=1
This again is sloppy. It works but if one is looking to your website for an answer they would be in trouble. If k1 was any number other that 1 the equation would be wrong. The equation should read k2=1/k2. Actually, I wouldn't even bother with k2 and just define your feed fowards like this (u+B1*u'+B2*u''+B3*u''')/k1
You are still using the feed forward crutch. When you have perfect feed forward gains then the PID tuning doesn't matter much because there should be no error. I know you use the feed forwards will mask the error in your tuning. I don't need to use feed forwards just to get a faster critically damped response than yours. If you are really clever you will find that you can design your controller to have a response like 0.0009887008 u ' ' + 0.0601797 u ' + u = w Then you will find feed fowards are not necessay for response to step changes in the set point.
Peter Nachtwey
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Sorry, you are on the wrong page. The task I refered to is http://home.arcor.de/janch/janch/_control/20070608-pd2 (pid)d0/ Exact definitions for K1 and K2 in page 3
--
Regards/Gre http://home.arcor.de/janch/janch/menue.htm
Jan C. Hoffmann eMail aktuell: snipped-for-privacy@nospam.arcornews.de
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Sorry, guys. I am asking short simple questions. One on each post. You can see that JCH somehow gets confused and never remembers to answer the questions. I am trying to keep it simple.
BTW, I think we are making progress. At least JCH isn't pushing his infinite gain controller anymore.
Peter Nachtwey
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