Bode Plots by Hand: Real Poles or Zeros
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- čas přidán 23. 10. 2012
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This is a continuation of the Control Systems Lectures. This video describes the benefit of being able to approximate a Bode plot by hand and explains what a Bode plot looks like for a transfer function with either a real pole or zero which does not lie at the origin. This is the third of several videos where I will describe step by step how to estimate a Bode plot from any transfer function.
I will be loading a new video each week and welcome suggestions for new topics. Please leave a comment or question below and I will do my best to address it. Thanks for watching!
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Brian Douglas for President.
Exactly what I am thinking!!!!
he is a father figure for us..
Your explanations just keeps filling the gaps I've been having all while. I really appreciate your effort and time in sharing this worthful piece of knowledge. Thanks
This video is the building blocks of my knowledge xD
After 10 Years your Videos in control Theory still the best ! Respect
The third dimension I drew was in the S-domain (explained better in the video on the Laplace transform). The real axis is sigma, the imaginary axis is omega, w, and the "z" axis isthe complex result of the Laplace transform. Sigma and w are locations in the S-plane. For frequency response (Bode) the Sigma term is zero. So all you are left with is the complex data (the z axis) along the imaginary line. The complex data is then converted to amplitude and phase to make two separate plots.
We are making bode plots for real value of poles/zeros in this video. You make the transfer function accordingly to fit real value of s but you check the response for complex value of s which is jw. Why is that?
@@rorschach4285 S actualy has a real and an imaginary part (S=a+jw) where a represents the exponential part and goes to zero in steady state. s=jw is sinusoidal part which represents the steady state response of the system, on which were are dealing with while using bode plot. So if H(jw) generates a real part, it's the steady-state response of TF, not the exponential term of S which goes to zero in steady state.
@@GundoganFatih makes sense. Thanks!
@@rorschach4285 You welcome!
Brian, thank you so much for the time you put into these videos!! They are amazing! Keep up the great work!!
I can never remember the names of any of my professors, but when I need help with control I instantly remember the name Brian Douglas.
Brian Douglas, you're a saint!
This man is a godsend! Loving the clear and concise lectures that show the exact algorithm behind graphing these things.
excellent! i love how you save time with the quick writing appearing, makes the video much more condense and easier to follow.
This is by far one of the best short lectures explaining these concepts on all of CZcams.
The way you explain is excellent. I beg you, please dont stop making these :)
These videos are amazing! I use them to supplement my engineering studies.
You're so good at drawing, as well!
Wow, using the information you know to manually estimate bode plots. Such a practical skill to have when you're in the field.
Thank you very much Brian, your videos are really helpful and enjoyable to watch.
Thank you very much Brian, your way to explain is amazing. Thanks for all the effort you put in these video series.
Your explanation made it clear and simple. Thank you so much!
Another amazing video with crystal clear explanation by Brain Douglas! God bless.
Youre a genius man, one of the best teachers Ive ever had
Thank you so much. The best classes about control theory.
You are Amazing!! Thank you for these videos, cant believe the cost of my ASU tuition and my professor came know where near to explaining BODE plots as you have in these videos!
Great class! You are the best teacher that I have seen!
Loving this series so far, thanks!!
Your expleanations are way better than my professors and I even under stand now how to draw way more complex transfer functions like the ones asked in our exam. Thank you so much :D
I am so grateful for these videos.
Wow this video is well thought through and crystal clear! Perfect material for my Control class!
These explanations are so elite. Thank you!
You're ability to draw these things in three dimensions really helps explain the concepts.
You are a hero! Thank you for teaching me stuff that I could not grasp in class
Wow (this is way easier than I presumed), my textbook could never reveal this insight if it tried! Thanks!
What a life saver. Your videos are simply amazing sir.
Amazing video........ 10 min from you = 50 minute lecture from my doc
continue the great work
thank you! you are so much more interesting and easy to understand than my controls textbook!!
My hat is off to you sir!! Well done.
Hello Ufuk Ozer, you are quite right! Thanks for the comment. Sometimes I forget that I have a large non-native english language following and that I should speak more slowly and carefully. I will try to keep that in mind when I make videos, but please ask me to clear something up if you don't understand.
Brian Douglas! you are too freaking good man! thanks a lot!
I want you to know that you're the reason that this makes sense now. thank you!!!!!!!!!!!!!!!!!!!!!!!
Thanks Brain. You saved my semester.
Hi Contradel, you know that this transfer function has two poles because of the order of the characteristic equation. Since it's 2nd order there are two poles. And you can solve for the roots using the quadratic equation, or factor the equation to be (s + 1000) * (s + 1000). So there is a double pole at s = - 1000.
I am following your videos. Great job, please continue.
thank you sir, you made my day!
The explanation at 11:20 helped me a lot.
Thanks for your effort! Appreciate for your wonderful teaching! GOD bless you!
This is so good!
Thank you so much for this video.
So
clear. thank you!
praise the savior of my 3rd year uni
The king in the lands of control engineers
I know some other viewers have figured out ways to download them but I'm not sure how (nor that it is CZcams approved)! Unfortunately I don't have another website or a place to make them available right now. Maybe one day. In the meantime you can see if there's a way to pull them off of CZcams.
Hi Brian, why didn’t you take the absolute value of the numerator and denominator of the initial transfer function? Why did you need to take the complex conjugate of it first? If you take the absolute value of the initial transfer function ( 1/(1+ s/omega)) wouldn’t you arrive at the same gain? Thanks!
hi brian ,thanks for that helpfull videos,even if we dont comment,still e are watching you all the time.
Our native language is not english and when you speak like in this video; we can understand you ,please keep in mind to not talk too fast.
thank you !!!! :)
Fantastic . Thank you for sharing
Greetings from Italy!
Hi Brian. Thank you very much for your videos, they are life savers for me as a third year student for mechanical engineering in Israel.
I was wandering what was the third dimension you drew in Im/Re figure.
Thank you.
Thank you, huge help!
real nice videos Brian :)
Thank you for these videos. Would even pay major $$$ for them.
Hi Brian, thanks for the video. I got everything you said in the video except the 3D visualization you showed for a pole. Can you please explain what is the 3rd dimension/3rd axis and how did you come up with the tapering tower that you created early on in the video. Thanks again!
It's soooooo good!
I curse those who made me hate control systems back in college! this guy is just making me fall for control systems
tnx man! that was helpful :)
Brilliant, cut off frequency understood very well. Cheers
Would you please explain about close loop bandwidth as well?
You're really good! Nice video!
thank you. very helpful.
Thank you very much.
What is the meaning of the (pink) line you drawn at 2:30 and what is the meaning of being elevated by the impact of the pole
Hello Servet, I would love to help you but unfortunately I don't understand your question. Are you asking what real life example (either analog circuit or digital circuit) would produce a zero in a transfer function? Please explain the question a little more and I'll try to help you.
Thank you so much!
So in this lecture a real zero is a value of 's' that causes the transfer function to equal zero and has the form real + 0*imag. Or only a real component. Hope that helps.
Why cant the lecturer teach us like this😍😍🔥🔥
Hi Brian! Actually, would it be up to me, your speed is just great. I like your approach as you are not wasting time as opposed to some other videos which are great for explanation, but they just make fall asleep. If I don't understand anything, the video can still be paused, so it's okay. (and I'm not native English either) Thanks for the explanations!
thanks for the video !
but can you please elaborate on the 3D plot with more details ? I mean how did you draw it ?
and on vertical axis of the 3D plot which quantity is there ?
That drawing at 2:35 (S plane). The sky opened, angels sung. Thank you.
You can find the same stuffs in some other youtube videos.
Just search laplace transform animation and you'll find the same concept explained visually using MATLAB.
@@aparnasadhukhan5567 Thanks man, I'm only studying this stuff as part of my hobby and this happened to be when something clicked for me. So I thought i'd show some appreciation is all.
Brilliant! what I don't understand is you mentioned in the last video that a pole makes the transfer function go to infinity, while the s in the new pole form here obviously can't make H(s) infinity but 0 instead! is there anything I missed or should we should accept the convention?
I redo the mathematical analysis and manage to get the bode plot. Anyway thanks for this awesome video! =D
thank you so much!
So extra thank you very much you help me a lot ❤️
Great Job Thanks a lot
great video
you are genius man. nice
Dear Brian, Great videos! Very concise and clear. Is the part where you equate w = wo and you obtain a value of 3dB related to determining the lower and upper cut-off frequency of an amplifier circuit? Since the lower and upper cut-off frequency from a frequency response curve are obtained by drawing a horizontal line through -3dB and marking the points where the line cuts the response curve.
Servet, it sounds like your professor was describing different definitions of zeros. Like how you described the absolute zero of nothing versus a reference zero in a test kit. Also, in the digital electronics world a zero represents a state of a logic gate (like a transistor or diode). But what I'm referring to here is a fourth definition of zero, that is, a value of 's' that causes the transfer function result to equal zero. And this value of s is in general a complex number, real + imag.
Two example problems for each video that we could do would be extremely helpful.
Brilliant drawing skill......
amazing thanks!
Do you have these sketches available as full res photos? I would love to have them around as references.
Dear Brian,
Very useful video. I have Question on basics.
Imagine i have a system with numerator (S+1), means i have a Real LHP zero at -1. Means whenever i apply exp(-t) signal to that system i would end up with Zero value of the O/P Quantity. here we can't find any real sinusoidal frequency which gives zero o/p value.
Similarly if i have a system with (S+1) in the denominator then i will get infinite response if i excite system with exp(-t) rather than a simple sin..
Could you please kindly tell me if there is any thing wrong with my understanding??
Hey Brian!
Thanks a lot for your videos! I'm studying digital control with a mathematics approach, and your videos, more intuitive, are really a perfect complement to have a good understanding of the subject! I have a question : 2 videos before this one, you're saying that s = jw for a steady state response, knowing that s is a real pole in this case. I don't understand why s = jw. Could you explain?
Continue to make videos, it's a real treasure of knowledge that you're sharing!
i loveeee itttt!!! thankssssssssss
Thanks a lot!
Thank you so much Sir :)
Hello Brian, A great work. I do appreciate. A suggestion to slow down the speed of lecture to be easy to absorb the informations while on the Go......
wow! thank you!
You are right, I've added an annotation so others won't get confused. I should have you proof all of my videos before I post them ...
Thanks for These Lectures...... Could you give lectures on state space please ?
fucking brilliant, i might pass now :)
makes sense finally
What setup do you use when making these videos, is it a tablet?
Great content by the way.
thank you
Hey Brian,
Can you make Videos on estimating phase compensation in Switch Mode power supplies controller?
Thanks alot for your valuable knowledge.
Great videos Brian. Can you explain the logic for the -20dB slope when w>>w0 @ 8:04 in more detail.
Could you explain why the phase behaves this way? From an analytical point of view, I mean. In fact, if I try to plot atan(w/w0), I get something that goes from -pi/2 to pi/2, not what it was shown in the video above. What exactly is the expression that you have been plotted? Could you help me?
Dear Brian, thanks a lot for your extraordinary clear videos! Well done! In a few minutes, plenty of condensed knowledge. Could you better explain the note about the influence of the real pole on the steady state answer? I don't understand the 3D graph you presented in the first minutes. Thanks, Davide.
I'm also wondering what is exactly the Z-axis in that plot.
Moises Ferber
If i'm not mistaken, the z-axis is the transfer function. So at the pole, the transfer function would be infinite, and at a zero, the transfer function would be 0. That is why you look at the denominator for the poles and the numerator for the zeros.
Thank you sir. :)