Control Systems Lectures - Closed Loop Control

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This lecture discusses the differences between open loop and closed loop control. 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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List of errata in this video:
- There is a missing "e" in the word change near the beginning
- There is a missing "l" in the work literally in the sprinkler system example
- There should be the reference signal "V" in the transfer function at the end of the lecture (this one I called out in the video).

[@psford1]

I hate uni because most professors seem to forget that they were ever students. In two short videos you have made this concept crystal clear. It's sad that it never fails that watching KZbin videos helps understanding better than 3 hours a week in a lecture. One more vote for YT degrees!

[@anicecrackhead]

School is a control system... You think they're gonna actually teach you shit.. Lol

[@OndraBF]

psford1 My words that first sentence.

[@1973jdmc]

This is just soooo true- sad but true- I came looking to find a simple well defined explanation, without Laplace crap- found it here-

[@prageethbhanuka7882]

totally aggree!

[@ShizzleMyChizzle]

Totally agree. Can we just ditch the idea of going to class already and do it all from home?

[@azinghaheri387]

in answer to your last question at the end of the video: I would say just by designing controller D, you can not make your plant G behave the way you want. because the plant might have some physical limitations. if you say I want to maintain a speed of 280 km, no matter what the controller's command is, "a not very strong car" might not be able to reach this speed.

[@GreatBearClaw]

+azin ghaheri sharghi Agreed. I also suspect the following: 1. We are assuming that we have captured a perfect model of the plant when there could be errors. For the car example we might have assumed a certain input-output characteristics for the gas pedal position vs the force generated by the engine, which might not be accurate. 2. What about external uncertainties? Such as in the car example the friction of the road varying at different places, wind etc. These are things that our entire model might not have captured.

[@absurdengineering]

Interesting Tidbit: There are dishwashers with water turbidity sensors. Turbidity means how much “crap” there is in the water, or how “unclean” it is. So the dishwasher will run some minimum number or length of cycles, and will add some to achieve desiredly low turbidity before moving on, or it can use the turbidity in open loop mode without changing the water: the more turbidity, the longer the main cycle that involves soap, since there’s no more soap once you dump that water. The dishwasher I have seems to run pre-rinsing in closed loop, where it’ll add up to 3 rinse cycles as needed to get the water sufficiently clean before the main wash. It’ll then time the main wash (with soap) based on how dirty the water is after a few minutes of washing.

[@elipayne2617]

Why do Professors get paid so much. This man taught me more in 9 minutes than my professor did in 4 hours of lectures.

[@BrianBDouglas]

I'm posting a video right now on the Laplace Transform. However, it's a graphical approach to the transform to try to give another perspective on what it is doing and how it allows us to solve differential equations. Khan Academy has some great videos on PFE which cover the basics. As far as when to use them with Laplace transforms I'll try to touch on that in a future video.

[@1973jdmc]

Thank you so so much for an excellent explanation.

[@Ensign_Cthulhu]

2:12 "The plant, which is the grass in this case..." Bringing literal (botanical) meaning to the technical term "plant".

[@FroggyOfWar]

the handwriting is so neat

[@theInternet633]

Perfectly well an clear until 6:55. I don't see how it's possible to understand this without prior knowledge of the subject. We haven't even established these Variables as functions yet and you already start multiplying them. At least my understanding is that they should be concatted and not multiplied just from what i can gather from the video. Not saying what you do is wrong, but i can't really understand it without already having known something this video didn't explain

[@xd-os7jl]

Yes, at this point you have get a book and read it. :/.

[@isaacdestura7495]

at that point, it just took off into space

[@kaleemullah5664]

this knowledge is obtained from the signal and analysis course and the topic is LTI system.

[@madhavansudhakar3295]

Agreed

[@tahaanwar5224]

im a little confused why is E = V - yH when it should be E(error) = V(desired) - y(output)

[@UpSwinging]

The way you organize the material in a step-by-step logical manner is extraordinary ... huge talent for teaching.

[@samgorman5731]

3rd Year Mechanical Engineering Student here, this stuff was completely over my head at first seemed so unusual but you do an excellent job of explaining everything, but a little fast. !

[@mynameis1880]

There are two ways to watch this video: 1) you pay attention to what he's writing, and listen to his words in the back of your mind. 2) you pay attention to what he's saying, and look at his sketches but don't really concentrate on them, your attention being occupied by his words. The second method of watching the video works. Not the first one. It's easier to keep listening to him, without looking at what he's writing. You can look at the screen and try to take on things from time to time, but you have to pay attention to his voice. Hope this helps someone!

[@SyedSaif17]

I watched this while doing the dishes and laundry and understood 70 % of it which is close to what a normal person would comprehend in an average classroom environment .

[@GreatBearClaw]

+Syed Saif I was in deep sleep while this video was playing. I only understood 80% of the lecture, something much higher that an avg attentive listener would ;)

[@poisonpotato1]

Dheeraj Reddy 2 years old, but not necessarily, some people are more auditory learners and some are more visual learners

[@xxMpEGxx]

watched another video and still understood 90% of this vid...what the joke's dead? alright then.........

[@mokka.naresh5835]

could you please explain control systems with regard to electrical components R,L, and C using practical examples

[@mohammaddawodi7484]

Although you talk a bit fast, but great job and I am happy to find you at the start point of my term for Modern Control System, I hope you have covered all the topics we need. Thanks for explaining in a very professional and simple manner.

[@ParadiseProjectsGroup]

+Mohammad Dawodi You can pause the video.

[@StonkeyKong]

This channel is awesome. I am going to watch every video. I am starting my master’s in Control Systems Engineering in Fall 2018, I am going to get a head start on a lot of the material with these videos. :D

[@TheHaloFan171]

how's the masters degree coming

[@StonkeyKong]

@@TheHaloFan171 ended up getting a masters in software engineering while working full-time. I am hoping to start a PhD in statistics.

[@TheHaloFan171]

@@StonkeyKong oh man, what a turn of events, what was your undergrad in?

[@StonkeyKong]

@@TheHaloFan171 electrical engineering, minor in physics.

[@TheHaloFan171]

@@StonkeyKong why'd you switch up from the original plan? was thinking about getting a master's in controls too

[@BrianBDouglas]

Hi Arsenal, I can't really number my videos because I don't post them in the order that a brand new person should watch them in. I sort of jump all around and it would take me a long time to constantly re-number them. However, I do make playlists of the various topics I cover and place the videos there in the order that people should watch them in. And I do keep those playlists up to date. Hope that helps. Cheers!

[@caleb_wole]

Hello Brian. Please can you recommend a textbook on Control Systems?

[@SaeedAcronia]

I am an M.Sc Control Engineering student at University of Rome. The faculty includes many of the greatest scholars of the field, say Alberto Isidori, Giuseppe Oriolo, Alexadnro De Luca, etc, all of whom are very well-known worldwide. Although being a great scientist doesn't necessarily signify of good teaching skills, I think the instructor here in this video is teaching just as good as them. Best of luck to all of you.

[@killyourdarling9699]

so your profs are great scientist but not good at teaching...mr brian teach as good as them which mean he is not good at teaching either ....failed

[@SaeedAcronia]

Mohamed Magdy You are being fallacious. You need to be inculcated a little bit of logic I guess. Check this page for a start en.wikipedia.org/wiki/List_of_fallacies Then read my propositions again.

[@killyourdarling9699]

i read your wiki page and it proved that you're wrong

[@SaeedAcronia]

Mohamed Magdy You just made one of the fallacies mentioned on that very page!

[@SaeedAcronia]

NO! You just made the fallacy of "Ignorantio Elenchi"! You established my sentence and inferred a false conclusion! I advised that being a great scientist does not mean that they are good teachers. You mistakenly deduced that I am saying: "They are not good teachers!". Actually they are good teachers, yet, being great in the field does not account for that. Then I added "I think . . .", to show that I am aware of this fact, but I want to give you my speculation on how they teach and how this person teaches.

[@86Ivar]

Instant subscription.

[@squeakyice-cream441]

One of the most interesting and understandable lecturers I've ever been lectured by, and i can listen to them over and over! Thank you very much

[@s07babee66]

😇💜🤲💡

[@yurioliveira6603]

Thank you for the errata list, I was looking for the missing "V" in the last "Y" equation. You're classes are very interesting, congratulations :-)

[@fanBladeOne]

Went into the comments just for this "V" I'm not going mad it seems :)

Wow thanks Brian, your video helped me a lot to understand this concept.

[@JunaidImtiaz1]

I literally paused the video to like this video and subscribe to this channel. Excellent video. Thanks a lot. Awesome work

[@shwetaarian7724]

me too , really brother i did the same:)

[@nityanand4914]

hi @brain Douglas, thanks for the video how can we determine wether the system is open loop or close loop just by seeing it's transfer function

[@trooperex123]

At 7:55 I didn't get how you got DGV = y(1 + DGH)? Pls clarify on this

[@AxiologyStudios]

I realize that your comment is 2 years old, but in case anyone else has this question, I am going to answer it. He gives us: E = V - yH & E = y/(DG) [transitive property] V - yH = y/(DG) [multiply each side by DG] DGV - yDGH = y [Add yDGH to each side] DGV = y + yDGH [Factor out y] DGV = y(1 + DGH) [Divide each side by (1+DGH)] DGV/(1+DGH) = y Hopefully that helps. For whoever happens to read this, have a wonderful day! :)

[@ipk4du]

Wonderful!

[@amoghdadhich9318]

What exactly do D and G represent here? Also, what are we doing when we multiply D and G; what does it physically mean? I assumed that they were functions, but then all of this wouldn't make sense.

[@ombhilare642]

D and G are just blocks (Each blocks may having it's unique components connection and transfer function) . So for sake of example he took D and G two blocks and connect them in cascaded form . Now the reason he multiply both D and G is to reduce the closed loop system to open loop control system. First solve the forward transfer function and then convert -ve / +ve feedback into open loop control system.

[@hediyehb9082]

you have no Idea how horribly this concept was thought at my university!!!! If you'd like I could send you the english script to the class just dried out awful

[@BrianBDouglas]

Thank you for the comment Ahmed. I can't promise the future videos will have such clear explanations, however, if anything is not clear please leave a comment and I'll respond to it.

[@HelterMcSkelter]

So the way I'm hearing it, "v" is the velocity we want the car to go. Let's say 100 mph. An example of a sensor here might be one that measures the rotational speed of a wheel on the car; so "y" could be its angular speed in rad/sec at any time. "H" is the conversion factor from rotational to linear speed -- in this case, it would be the radius of the wheel (with a unit conversion). Given all that, I get why "E = v - yH" But can someone please explain why "y = EDG"? What are those variables?

[@maerufomer5469]

hi brian, i'm a fan of ur work here. but i'm an engineering student and our teacher tought us abt type of control sytems as natural and artificial, i would happy if do some tutorial abt other kid of classification of control systems

[@56004712]

All the videos very helpful for my control system exams... Thank you very much...!!!

[@BrianBDouglas]

Trunks, thanks for the comment! I've just started the series and I plan on taking it through classical control, modern control, dynamics, sensors and actuation. Or at least as long as there is an interest on KZbin to have me continue.

[@teargun1]

Man, I like from no where arrived here, watched your videos and am thinking, WOW!!!!......so simply put and explained.. For a foreigner studying in China, and not understanding anything the lecturers are bubbling about in classes (because all lectures are in Chinese), these videos are really helping me... Peace and God bless you for the free knowledge....Please continue..and you write very good and as fast as you talk too..cool....:)

[@jeffryyapin1399]

Thanks a lot the way you explain it is really great... it's really help...

[@cakdian]

Thank you Brian Nice presentation, very helpfull I permit to download this video

[@atenaten4017]

thank you so much!!your video really make me understand even more about control system.

[@devangmarvania]

Very well done sir! Hope you will continue in future..wish you all lights green

[@Idlehampster]

Unlike websites I've searched for explaining closed loop control, your video gives definition to "Control Loop" and "Control Theory" in a way that is easy to understand. Thank you!

[@mcr1981]

Thanks for this effort. Can you tell me what software and hardware you use for this lectures?

[@philosoraptor56]

Starting here to learn a semesters worth of controls before Thursday. OHHH YEAHHH

[@oish3763]

7 years later here I am. FUCK YEAAAAAAAA. thanks brian saving lives

[@RRP3168]

Great video Brian! Helped me a lot! Thanks.

[@Tim_Linkel]

Thank you Brain for the awesome lecture. I have a question, is there a mistake DGV=y(1+DGH) or y=DG/(1+DGH)? Where is V? dont get it. It should looks like y=DGV/(1+DGH) shoudnt?

[@theultramagicballoons8799]

I don't get this either.. Anyone who has a clue?

[@paul1964uk]

8:34 I think the limiting factor is the assumption of linearity (embodied in the final algebraic expression for the plant) underlying the model. There is nothing that in practice behaves in such an idealised manner so our attempt at control is limited to a range. Nice and easy to follow. Thank you.

[@kamranullah6857]

Thank U sir... :) U r the Best.. :)

[@lewa1221]

This is very helpful... Thank you

[@iforce2d]

7:18 I don't quite get why H is included in E = V - yH Is this to somehow account for the sensor not being a perfect measurement? I'll watch some more of your excellent videos, maybe it will become clear.

[@ChunkOfNorris]

It's ther because E= the thing from the left (V) - the thing from the bottom (y*H). Because it's included in the model it has to be included in the equation no matter what it is. I guess it could be something other than a sensor.

[@nkboon1234]

i think its because the basis of comparison of V is the interaction of both y and H. ie: the effect of y on H(the sensor) yields a result that forms a common ground to compare with V

[@erwincabatingan675]

Thank God and to you, I found your channel and it's very useful in my study.

[@faisalal-balawi1473]

thanks man you clearly explained that . the best tutorial video ever !

[@neonoto7526]

thanks. had to brush up my basics for an on job exam. your playlist was a lifesaver.

[@vivekkumar-py6kp]

I didn't understand the derivation (the formula part).Overall video is good.

[@easyelectronicsru]

Cool cool! I do not know much English, but when I looked into it then at the university. Now here's the recall. It would be great if there were subtitles, at least in English. To be translated into Russian Google translator.

[@ChintanMeena]

You sir are Hero. Thanks for lecture :) ! Amazing work

[@swamijayaraman7538]

is the equation y in terms of EDH trying to say that every closed loop system can be represented as a open loop equivalent ? if so, this is not sounding intuitive... can someone explain ? tnx.

[@kamaniIG]

thankyou sir very much for creating these video tutorials and they are really really helpful and very clear for students. i would be much grateful if you can do something regarding the nyquist plots :) once again Thankyou!! and keep up the good work :)

[@SoloPlax]

These lectures are ABSOLUTELY the Best I have ever encountered on Control Systems! You are brilliant! Thank you Brian. I will defnitely purchase your book. Please add lots of real-world examples + MATLAB/SciLAB in your book.

[@MrAndreaCaso]

Creating two different playlists was an excellent idea. Thank you Brian, fantastic job!

[@TheBirdMan]

Guys watch all series. Best control systems lectures on Internet.

[@akeelwannas4165]

You are the best, everything in your videos are beautiful, thank you.

[@tanko2673]

i dont know if you still use this channel but I wanted to thank you from Poland Politechnika Gdańska, very good tutorial!

[@SN1350]

Learned more about control systems in this video than all the lectures and text books put together. Nice job.

[@isjoker22]

If it is 1/10th as clear, it will still be roughly 100% better than my instructors rendition of how control theory works, no exaggeration, well maybe a little, maybe 98%. The sad part is that I attend a school that is ranked #5 in the US for top electrical engineering schools. Thank you very much. Subscribed!

[@matiuBlog]

Great video!! Thanks a lot. I took control courses a long time ago, very nice to refresh the knowledge! BTW, What software are you using to produce this?

[@PotadoTomado]

Wow, super interesting! 7:15 and beyond is especially cool, since I had never seen someone manipulate flow chat symbols algebraically like that.

[@asifing24x7]

Very well made and helpful videos...Thank you!

[@moisesferber]

excellent quality! thank you

[@simasjanusas1766]

First minute in: this might be boring but I'm interested. Two minutes in: this is interesting, the guy explains well, I'm still following. Three minutes in: son of a gun, I'm in. Four minutes: when do we start.

[@ahmedImam]

OMG this is awesome please continue the video is amazing you drawing and simple explanation is spectacular you simply said what we gave in two lectures in ten minutes continue continue continue continue continue continue continue continue continue continue continue continue continue continue continue continue continue continue continue continue continue continue continue continue continue continue continue continue continue continue continue continue :)

[@Xeon1007]

bro you got so annoying voice, it doesn't help to immerse into lecture and soak in all the content. But Brian nice you doing this job, maybe it's just the accent but it's frustrating because I want and don't want to watch it;) just I think it's worth giving this feedback for future lectures.

[@MrGooglevideoviewer]

Great first video and intro Brian. I'm no newcomer to control systems. Was often thinking about how to begin some introductory videos on the topic. Much admiration from me on your efforts. Well done, great job! 😊😊

[@Spardeth]

Great videos, very instructive. Thanks for sharing your controls knowledge! :)

[@LilyThong]

Audio out of sync? This is a bit difficult for non-native English speakers to learn😂

[@arash4232]

Hi, At 7:30, y=E.D.G, is confusing for me; Suppose error=0, output will be zero as well! y=v.D.G makes more sense. Where is my mistake?

[@SimmacoDiMaio]

Thank you so much!

[@fahmylina123]

الفرق بين السبهللهة وبين التحكم هو الفرق البديهى الأولى (وإن كانت هذه المقارنة ليست سليمة تماماً كل الأحوال) بين (دورية مفتوحة) و(دورية (مغلقة) أى مزودة بوحدة تحكم تتخذ قرار تحكم ما فى اتجاه ما (لتحسين المخرجات المرغوبة وفقاً لحالة المدخلات) مجرد مدخل (مقدمة) مبسطة إلى نظم التحكم

[@RealShadowStar]

Awesome, i am so glad i found all of this as it will help my Controll Systems Engineering Course. You Brian Douglas is truly awesome!

[@pladselsker8340]

I'm having a hard time understanding how you can just multiply your transfer functions together even though it seems to me that they are not multiplied together, but rather they compose each other. Like, P(C(E(input, F(y)))) = y does not equal the equation you came up with in the video, at least not from my perspective. Is this a property of transfer functions or something?

[@sannyavm]

thank you so much dude, for me it's easy to understand rather than my lecturer's explanation

[@sushanthkumar533]

sir if we assume gains to be some finite value that is G = 4,H =4, and input signal to be 4u(t),then how exactly the output is generated, If we assume initial output to b zero then ,is the output at that instant is 16u(t), and will the signal future iterates throughout the blocks..... i mean could you please explain how exactly output is generated.... i need it because i am learning op-Amps,where both G and and H are finite values..Thank you

[@jessasto947]

In the beginning was the Word, and the Word was with God, and the Word was God. 2He was with God in the beginning. 3Through him all things were made; without him nothing was made that has been made. (John 1:1-3)

[@JoshC0364]

Amazing!! Thanks a lot for taking the time to share your knowledge... Keep going please!!

[@moeka4260]

The acrid elbow evocatively invent because sentence fundamentally bless around a frequent hubcap. prickly, beautiful correspondent

[@TheKiltedEngineer]

Perhaps you can help me out. I am an ME student, and understand the mathematics behind control theory. I can do the problems, but I am struggling with actual applications, which I really want to learn. My main is issue is understanding what the equations actually mean. I read somewhere that "electric motors have two poles, subway cars have nine, aircraft may have 26 and spacecraft possibly one hundred" What exactly causes poles to be induced into a system i.e. what is their physical significance.

[@SaisBlade]

Stumbled upon this with 0 background (software engineer with high school math background) Was interested and followed up until about 7:00 where the math broke out with notationand concepts that were glossed over as "a bit of algebra" I get that there are prerequesites but since the intro video framed this as being a sort of casual introduction giving a quick overview of math topics and\or referring to terminology\videos to lookup would be really helpful.

[@tricky778]

It's not from mere simplicity that we have open loop control. Of course it's closed loop in a way because there's a human in the loop, and in the last few years that has begun to weigh heavy in the public zeitgeist. If you have sensors and actuators powerful enough to detect a lack of cleanliness in the outgoing plates, you might find someone inserts a control program powerful enough to enslave humanity to fix the problem or to trick them into neglecting more serious problems or prevent them from choosing to stop running the dishwasher and find alternatives like disposable plates.

[@vikashdubey6840]

Thanks alot! Really wonderful explanation crystal clear. 🤘🤘

[@holyshiteballs]

If E=V-yh, wouldn't that make the car example E=100-(100)*(100)?

[@michaelmcleary8566]

You can't turn an ordinary car into a race car just by applying more fuel! You can make them go quicker but pushing them beyond their design engineering point will blow 'em up - but that may be fun!

[@dvscrobe]

Hello Brian. Thanks for these videos. I am preparing for a college course on control systems. I like how you came up with the concept for the transfer function in order to look at a system as open loop.

[@muhammedshafi8093]

💓💓💓💓💓💓

[@aerospaceengineering9542]

Well, the last block diagrams are said to be equivalent. But how will the open loop block diagram run in loops if it's only one step? How does it even go back and correct the output?

[@alexyangfox]

a Ferrari can be much faster than a pinto... So. we must make the term in the denominator be less than one ...DGH must be negative... Is that always possible in real applications?

[@SalvierDmello]

Awesome lecture! thanks for the explaination with examples, complete guidance for basic control system i like those fast videos with quick examples ,,,,goood one

[@zrmsraggot]

In a closed loop system for sprinkler device, the soil moisture sensor will take a long time before the water goes into the soil so you would keep watering for nothing I guess ..Like you wouldn't know as you read this com if the Sun died 7 minutes ago

[@gregstearn1479]

Great video just a little stuck at around 7:50 when solving y w.r.t v to get the transfer function? My maths isn't great so although this step is relatively easy I can't work it out without step by step instruction. Any help appreciated.

[@theboxdev]

How the 'grass and soil' is a 'PLANT' but the sprinkler isn't?

[@inobotics]

This is really amazing work....! Now I dont need to wait for this course to be taught in my class which is next year!! I wish my profs would teach stuff this way.....giving emphasis on the physical significance...KEEP UP THE GOOD WORK :D Hope to see more of your videos coming up!! Thanks a lot :)

[@alexyangfox]

Looks like ...The Closed loop can be seen as an open loop system , but this open loop system has a very specific input which is different from the ones above...Its input is some kind of criterion..

[@mahmoudbakr568]

@Brian Douglas what is the difference between control theory and machine learning (AI) ?

[@shravangulvadi]

Since we call E as error signal, it means that we want the output y to be equal to reference V. Doesn't that mean tat we want the transfer function to approach unity with time (so that the reference input and output are equal). But there are no discussions in control along these lines, why? What is wrong with my thought process?

[@logeshlee1847]

i want say some well deserved yters drop the channel due to no views but we can't blame them in 2019 actors makes more than engineer s but man if ever read my comment keep ur work and upload atleast 2mnth once ,a movie is onetime but knowledge is something incomparable

[@TheCsePower]

Wait isnt that what machine learning is about? I think they have progras which adapt themselves depending on feedback until their output becomes perfect

[@mikaelnias263]

thats video so amazing,i've got very useful basic concept which i don't get in my university