Control System Lectures - Bode Plots, Introduction

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This lecture is an introduction to frequency response methods, and in particular describes the Bode plot. I go through how it is generated and why we use it to visualize the frequency response of a system across the entire frequency spectrum.
Errata:
8:31 - I should not have combined both time domain and s-domain in a single equation.
9:31 - it should be 2 - j*1/omega, I correct it at 9:55 but don't let it confuse you!
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!
Don't forget to subscribe! Follow me on Twitter @BrianBDouglas!

[@therealgoat3367]

POV you're in the most challenging stage of your academic career. Good luck

[@alexpatterson5954]

This is amazing! My signals professor doesn't teach very well and now that we've switched to remote learning, he doesn't give us any lectures and only gives us written handouts that are sometimes hard to understand. I love how succinct yet in depth your videos are! You have no clue how much this helps

[@pranjalsachan1179]

This is the best playlist out there for understanding bode plots. Believe me, I am an Electrical Engineer and have studied bode plots a number of times but never had such an understanding.

[@azscott8737]

The things I learned in these video are way more valuable than the ones I learned over two semesters of control courses. This guy tells you every thing why they are there and where they came from and so on. I wish if I had him as a control professor

[@patriceamyot4235]

your explanation of the history of decibels is amazing and thorough! Very impressed!

[@BrianBDouglas]

Hello Samay, You are absolutely correct. I should have written the equation in the S-domain completely, or Y(s)=2U(s)+U(s)/s. However, I accidentally left the input and output in the time domain. Thanks for pointing this out. I hope this doesn't confuse anyone watching the video.

[@DrgonMark]

İ was confused last year but got 100 mark! Thanks bro. 😂

[@Johnyindo387]

Jakun ge ital😊

[@RC_Engineering]

You may be the best in the world at explaining these concepts. At least for my style of learning.

[@grace9465]

agree

[@RC_Engineering]

Brian Douglas My whole control systems class at UCSD thanks you

[@TheSlyProfessor]

I am funnily also at UCSD, albeit studying computer music. I finally understand why LTI's matter. They don't seem so arbitrary anymore. Now to finish watching all your other videos (which brought me here)...

[@paulnnamdi4098]

Exactly the same with me. The way he exlains it is best I have come across ever. Wonder why a lot of other teachers do it the way they do.

[@joannqiongnachen9849]

Agree! I won't be able to survive my control system exam without him

[@anantikamehra1694]

I love how everything somehow starts to make sense after you explain it. Thanks so much for taking the time out to make these videos!

[@Poiarn]

I've never seen or read anything that comes even remotely close to how good this video explains bode plots! Really good job!!

[@BrianBDouglas]

Absolutely! I'm finishing with Bode this week and then want to provide a good practical understanding of stability. I'll touch on root locus at the end of the stability portion and as we get into tuning controllers.

[@johnsalvadoresabio2491]

The quality of your videos speak to how much time and effort you put into your channel. Thank you so much.

[@vargil777]

Dear Brian, your efforts are much appreciated. You made the understanding of control systems very easy, you are the best in making us to visualize the concepts in a deeper sense, your way of presenting is so good that any non-technical person also can understand it. I request you to make a video on how to analyze and understand control concepts using Nichols charts. Thank you.

[@eugenenazarenko9220]

This was an amazing video. I was shocked to see it is over 10 years old at this point, unreal quality!

[@ricky-lee7553]

I paused the video around 9:40 then spent 10 minutes trying to figure out how to get 2+(1/w)j when i kept getting 2-(1/w)j. in the end i gave up and decided to watch the rest of the video anyway only to find you corrected it as a mistake 10 seconds later at 9:50 -_-... That said, your style of videos are absolutely brilliant!!!... so ill let you off this one time =] Cheers!!!

[@Natester13]

Saw the samething, glad I saw this comment before I complained lol

[@nirbhaythacker6662]

I was doing the same thing, thank god for you that i didn't waste half an hour rummaging through textbooks and google thinking "there must be some other reason as to why he did that, something more complicated".

[@thehomiebearfifa3528]

lol thats what being a student engineer is in a nutshell

[@Barneyismyname]

Haha i saw it too so I went to the comments instead to see if someone pointed it out, your comment saved me from spending 10 minutes as well :)

[@victorwainaina2584]

.......I'm a 3rd year engineering student and it took me 10min to figure out why you were all getting that solution....Don't worry though because I'm trying my hardest to get away from this course. Better 3years late than never, haha

[@afdelgado1]

damn... I hate learning material without the history behind it. It's so important in my opinion this literally took like 100 page description in the book and broke it down in less than 13 minutes. thanks

[@ALAAAJAJvideo]

Since 2012 (10 Years) this is the best Video about Bode Plots

[@sallymin0501]

I am Korean and studying aerospace mechanical engineering now. I was struggling with these concepts cuz these things were all new and I didnt know what to do ;(. But, god blessed me and I found these videos so that I can rearrange my concepts through all parts of controlling system. Thank you very much for all these super lectures ♥

[@rileystewart9165]

Love the lectures! You're changing the world. Legit. Bringing quality education to the masses. Thank you!

[@TY-un4no]

I replayed the section explaining the history of decibel unit many times because I was easily distracted by your skilled drawings haha. Thank you for creating clear and fun educational videos!

[@jacobhardy2313]

Taught me what my vibrations/control professor couldn’t in a whole semester. Thank you

[@ahxishwe5664]

Just realized i had subscribed 10 years back. And i still need to watch your video today. ❤

[@dylanschink240]

These lectures are so helpful, I wouldn't be passing with control theory module without them.

[@BrianBDouglas]

I'll try to explain it beyond just "The math says so!" :) Look at the equation around 8:30, the input u(t) is affected through two different paths to produce the output. As frequency increases to infinity the 1/s (or integral path) get's closer and closer to zero. You can imagine looking at a really high frequency sine wave and integrating the signal over time. Once the frequency become infinite essentially the area above and the area below the center line both go to zero.

[@shanugarg8428]

Oh Mr Douglas, you're just awesome. I just couldn't connects these different topics from Fourier and Laplace to s-plane and what's bode plot... I just love the way you teach all these so simply. I would really appreciate if you suggest me something to feel these things deeply to think and analyse. As a would be engineer, I don't want this awesome subject to go apart of me after I know how awesome it is. No doubt your lectures are end to end to grasp the concept but ultimately practice and self exploration is the key. And you understand the things I should go through as only engineer can understand and find an engineer inside a student. Professors just teach for exams and I'm not in face of marks. I'll end my words with the request to reply to this and help me with suggesting resources.

[@AdityaMishra-pp1gw]

@@shanugarg8428 You can easily use Matlab and Simulink to visualize all this concepts.

[@ONinjaPlz]

I wish I discovered you back when I took digital signal processing. I learned how to "go through the motions" in that class well enough to pass but without actually understanding anything I was doing. Thank you so much!!!

[@naut_nigel]

I can't believe it took me 2 years after graduating when I'm at a professional job to find these hidden gems of videos! Thank you!!

[@jeanapp_]

Love the fact that you use so many colors in your video. Makes the complete subject much easier to concentrate for me. I'm a person who thinks graphically so the pictures have to be good, colorful, but with only the essential information in order for me to stay interested (which is not an easy task, as I have noticed ;)), but your video makes me feel that I can understand control systems. Thank you so much! (Love the Mr. Bell that you drew btw)

[@pranayparekh4306]

thanks, you are a true legend! the difference between you and my professor's is they teach cause theyre paid and don't care about us, while you are teaching and saving us! you've saved me with control systems!!

[@raghuramsatish5995]

you sir deserve a medal Mr.Brian Douglas

[@muratmillidere]

Brian,you are just perfect. Everyone who is interested in control system should watch these videos.

[@jordannoel5826]

Thank you so much for these videos. I'm recommending them to all my friends. A million times better than the textbook we have!

[@Ryan-jl5yn]

bro you absolutely smashed this course! I'm probably not going to my signals class ever again

[@BrianBDouglas]

Yes, obsession is good word! We are obsessed with sinusoids because Fourier analysis tells us that any arbitrary signal can be represented by a series of sinusoids. In that way we can predict how a system will be affected by any input by knowing how each individual sinusoid is affected.

[@aliusef2912]

"Your explanation of control systems is amazing. You absolutely nailed it, my friend."

[@fernando2011]

EE student on senior year. Super appreciate this intuitive outlook on bode plots.

[@Geddiz]

Mate your videos have just about saved my EEE degree, thank you so much for uploading these.

[@angelivangamboa769]

Love your videos. you "learned" me this material in a night when my professor took 10 weeks confusing me...Thanks for the videos! keep up the good work

[@manueljenkin95]

Such an amazing lecture series, so few comments. Extremely underrated (most of educational resources at KZbin feel this way).

[@percyjacks8170]

Awesome video as usual and that sketch was awesome!

[@TheGiota100]

Very helpful! Thanks! Studying two days before exams these things ain't easy and your video really did help!

[@neelamrajkumar3254]

This led me to enlightenment in control engineering.Great lecture and let's make this lectures to be known for content seekers by sharing 👏

[@masoudkhamushi9821]

well, i dont know how to thank you brian but i can say you are the best, indeed you are thank you

[@BrianBDouglas]

Hi Bill, I will be uploading 4 new videos by the end of the weekend but they will all be on very specific concepts in drawing Bode plots by hand. I wish I had the time to make more of these but I'm normally limited to just one a week. Best of luck on the PE!

[@radoyapanic1669]

One of the best youtube lectures I've seen. Thank You.

[@HassanOmariprofile]

I have to say this, you are the greatest control teacher I have ever seen

[@jovanasavic4357]

You've saved my lazy ass once again. Thank you for this amazing lectures!

[@Zvanteman]

Missed my courses lecture on bode diagrams, this is a life saver! Thanks!

[@alexissanchez9730]

this is what im waiting to watch on youtube , very good job Professor

[@mohammedkhalid9317]

I've been suffering trying to understand these concepts but now you have just solved my problem ,thanks a lot

[@stephenshaw1858]

Great descriptions mate, appreciate your videos making simple explanations on quite a difficult topic.

[@Abayas.]

I know my professor means well, but boy oh boy do your explanations blow his out of the water! Thank you for putting this up.

[@anukritsaxena6328]

thanks brian, m learning bode this time... and thanks to you!! hats off - you are doing a good job educating people around the globe :)

[@rickydags]

This just saved my butt for my control systems homework! You are so much better than my actual professor! Thank you!

[@GopalGupta15]

Excellent tutorial for beginner to understand the basics!!

[@renandebritoleme3097]

Great class! You are the best teacher that I have seen!

[@matheuscamargo9187]

Excellent explanation. I don't even know English so good, but i've understood almost 100% of the content. Thanks!

[@deuss001]

Excellent explanation, brought me back to school of what I remembered about this work...

[@ejminava407]

Thank you for taking the time, this is very clear

[@imanbagheri1140]

I wanted to appreciate you for this tutorial, thanks brother, it was definitely helpful

[@rohanpandya7739]

Thank you Brian, you make controls fun!

[@zz9758]

Thank you for your hard work to make us understand this!

[@kunal-chandra]

Excellent video with all basic concepts revised for explanation.

[@perekelund7312]

Astonishing lecture! Thank you ever so much!

[@RUBENKI-cv8cq]

From Ecatepec, edo. Mex. Thank you for your explanation. The concept will be better understood.

[@monicag1115]

Outstanding!! Thank you so much for making these videos!

[@WalidIssa]

at 8:31 it is not correct to write the equation in time and s-domain concurrently. Thanks AWSOME

[@BrianBDouglas]

Yes! I have a bad habit of combining domains like that. ;) I'm trying to catch them and add annotations to correct my mistakes. Thanks for pointing this out.

[@Rockyfish3]

Walid Issa Yep you are correct. H(t) = y(t)/u(t) = 2 + (1/s)

[@youmah25]

شكرا

[@NikolaosPapadakis]

Isn't it correct to write it as H(s)= Y(s)/U(s) = 2+1/s

[@shrinivasiyengar5799]

Can someone mention what is the correct way of writing?

[@tomylim6022]

holy cow!!! the drawing is good too...this guy is multi-talent :D

[@nadie-qm8rq]

this video was soooooooooooooooooooo useful, I understood so many concepts, the introduction really helped

[@pawanbhatla2711]

Amazing content. I always used to wonder why are we multiplying 20 time log for decibels. Thank you so much.

[@RanjithSethu_findmehere]

sir, in the beginning of video you said about sine wave and linearity , it was thought provoking i say. Now i got a new way of differentiating linear element and non linear element in circuit components , thanku

[@JB-123]

That was an amazing lecture. I would pay money for a full course in feedback by you, not even kidding.

[@BrianBDouglas]

Hi Stephanie, the diagram at the beginning of the video had an integral in the lower path. When you take the Laplace Transform of an integral you get 1/s. 1/s is the S-domain representation of integration.

[@aaronbissoondial7659]

This saved me so much time. Amazing explanation!!!

[@atirahismail598]

This really saves me for my mid-session tomorrow!

[@nivpeer2052]

Thank you for the simple yet very informative lecture

[@zedlepplin9450]

Man, that was very well explained; another subscriber here. Thanks man!

[@BleepBloop69420]

you explain these concepts much better than my professor can in an hour and a half

[@Adhithya1002]

Exactly, I don't know why I am paying ton of money to university :| after all youtube is what helping me.

[@adityachaurasia2532]

8 years later still helping me. Thanks

[@BrianBDouglas]

About your second question. 1/j = -j; Therefore, 2 + 1/(jw) = 2-(1/w)j. When you are plotting on a real/imaginary plot you need to manipulate the value to be in the form real + imag * j, where j is in the numerator. Hope that helps. If you have more questions please leave another comment.

[@olivermechling7975]

such a great video thanks for making this series Brian :)

[@fabiospinelli4179]

wow amazing video in less than 13 minutes you did what my professor failed to do in more than 5 hours of lesson

[@shobhitvoleti1439]

Love the lectures. Thanks a ton!

[@aman_]

You are really awesome... You just connected my neurons together to understand bode plot.... You are great...

[@drewpierpont3361]

Wow, thank you so much Brian!!

[@taremekedzwamudzokora5373]

thanks Brian you made control so much easier !!

[@bossraden6671]

very nice explanation Brian! thank you

[@eamonhannon1103]

Brilliant video ! So well explained !

[@agggg3524]

You presented me powerful insights. Thank you

[@mohithkanala8228]

Great Introduction BRO!

[@5430mr]

You are amazing! I learned these ideas at uni, got good grate back then BUT god I had no idea about the concept behind them. Now I understand!

[@jacclawrence2951]

this saved my life, thank you so much

[@BrianBDouglas]

Yes you are right ... but I corrected it at 9:55. Good catch!

[@marcus4536]

Great video Brian, thanks a lot! Keep helping us :-)

[@ventjemazzel8822]

Excellent teaching sir! Many thanks!

[@rudrajeet814]

Wow such great intuitive understanding ❤

[@katharinelewis1]

this was SO helpful. Thank you!

[@LightAndSportyGuy]

These really are nicely done videos.

[@felipekersting7065]

VERY good lecture. Thank you very much!

[@kadiryilmaz7378]

Thanx man. Really helpfull. My prof. went really fast over these and I think that was pitty because these are really interresting stuff. So thanx a lot. And a happy new year to all of you.

[@BrianBDouglas]

j = sqrt(-1) so the problem in 1/sqrt(-1). To get the sqrt(-1) in the numerator you have to multiply sqrt(-1)/sqrt(-1). That leaves you with sqrt(-1) / sqrt(-1)^2 which just equals sqrt(-1)/-1 or -j.

[@rafaelgonzalez872]

I was looking for the answer to just this in the comments and you delivered. Appreciate it!!!!

[@elvenkim]

i love how you draw Alexander Graham Bell's figure!! so cute!!