Derive Transfer Function from Block Diagrams 2-FE/EIT Exam

Example Problem on how to derive closed loop transfer function from Block Diagram

[@airbender9593]

Thank you. I was worried that I may forget the material after learning this subject 20 years ago but it is understandable after watching the video 2x speed.

[@RaiyaAcademy]

You're welcome.

[@user-lb9pe9ek1r]

Thank you so much!!! I found I pass the FE exam today. I have recommended your videos to my Professors. Thank you again!! It helps a lotttttttttt!

[@airbender9593]

Congrats. How was the FE exam? How long did you prep for it and which material did you use?

[@chenmwu]

Thank you for the refresher. I passed FE 12 years ago and don't remember a thing about block diagram to transfer function, needed to use it recently.

[@RaiyaAcademy]

Awesome! You're welcome.

[@edmondscott7444]

Very well explained ma'am. What book are you using?

[@siddiqisah1452]

Almost divide through by r(s) but anywho...thanks a lot man

[@mattgallagher7105]

In case you still check this - In my problem, I get the right answer follwing your steps, except I have to assume the term containing L(s) (which is the disturbance, I'm guessing) is equal to 0. Is that normal? Thanks for the video regardless.

[@ironman-bz7wx]

Love u mam thanks for the clarityy😊😊👍

[@mogarr3574]

Thank you so much, this definitely helped a lot :)

[@MovementJR]

And to find y over r, the actual transfer function?

[@RaiyaAcademy]

In this particular case, you have both R(s) and L(s) so if you want Y(s)/R(s) mathematically then you subtract the function containing L(s) from Y(s) on the other side and divide both sides by R(s). You simplify from there. Typically though, we only have R(s) to deal with instead L(s) which would have been straightforward to find Y(s)/R(s). Hope that helps.

[@MovementJR]

Raiya Energy Thanks. And how do you eliminate L(S) (the disturbance) from the equation? Simplifying I end up with the transfer function multiplied by L(S)/R(S)

[@RaiyaAcademy]

MovementJR Yes that's the issue right there. L(s) is part of the whole function so you can't eliminate it. Y(s) is related to both R(s) and L(s). Mathematically, it's difficult to get Y(s)/(R(s) separately without having it appear in L(s). I never tried it. So whenever you have a disturbance, just write Y(s) in terms of both. Look up Page 123 on your handbook.

[@xMrJanuaryx]

If you want the describe the system in terms of a single transfer function then you can use super-position.

[@gordonaughenbaugh9004]

Algebruh

[@Chiragsmitfiji]

great explaination.....loved it :)

[@SpiffyGolfTV]

Chirag Patel when are start to study system in America? I'm Italian and i'm start studied system when i have 17 years old in the school in Italy.

[@duncankroll8923]

I am studying control systems for the first time in my senior year of college in chemical engineering at Michigan State. I am 21 years old.

[@glorychukwuemeka1180]

Thanks a lot for this!

[@piratenu1]

So where is the transfer function?

[@hugopontes4989]

I know its a bit late but maybe someone who sees this comment doesn't know too : The transfer function is Y(s)/R(s)

[@danielgiraldoguzman]

@@hugopontes4989 Obviously you haven't seen that you cannot simply divide Y(s)/R(s) in that expression. The question is still open.

[@hugopontes4989]

@@danielgiraldoguzman Well yes you can? Anyway maybe its not in the format you were hoping for maybe but I think its the best we can do with the given data..but im not sure so if you or someone has a better answer please ellaborate

[@quentinsylwester635]

@@hugopontes4989 so is there 2 transfer functions? Y/R and Y/L

[@haseebkhawaja1050]

​@@danielgiraldoguzman we can multiply and divide R(s) for first term and then take R(s) common and then divide on left side....

[@mareysaad6597]

Thanks

[@syaziwe]

thank you

[@mrunalahirao9256]

thnx for sharing!

[@RaiyaAcademy]

You're welcome.

[@younedward]

Thanks!

[@vishalsinghkatal7519]

can we use normal differential equation instead of their Laplace transform to draw a block diagram and if yes then how to join two different differential equations of same system to draw a block diagram? thanx in advance.

[@yyyd6559]

Yes i think you can use normal differential equation but Laplace transform is usually easier

[@onemillion210]

good

[@arthurbenedetti9146]

what if i need e/L?

[@kamrankhanUSA]

Not helpful