What are Transfer Functions? | Control Systems in Practice

This video introduces transfer functions - a compact way of representing the relationship between the input into a system and its output. It covers why transfer functions are so popular and what they are used for.

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[Erowens]

10 minute video teaches me more than 4 hours of lectures. Bravo.

[jiefang]

I have to say, you are the King of explaination of control system.

[Amine-gzgq]

For the Laplace Transform demos, I can recommend Khan Academy playlist. In a nutshell, Laplace Transform scans (like a sensor) for exponentials (natural/proportional to itself evolutions of something like bacteria growth, radioactive decay, compound interest stuff that can be modeled using exp(x)) and sinusoids (cos, sin and a mix of them, Fourier Transform does that too), poles are the exponentials, sinusoids or mix of both that your function contains, a resonance that creates a peak (the pole). e.g.: a wind can cause a bridge to sway at its natural frequency, which can break it (this has already happened). If we can model the bridge mathematically and use the Laplace transform, we can find out the bridge's natural frequency and prevent a future tragedy.

[LudmillaAires]

So much better than at least 3 years of electrical engineering classes.

[matthewjames]

For anyone curious about the definition of gain (like I was) here's a more detailed explanation:

The final steady state value of y(t) is given by the formula:
y_ss = (lim s-->0) s*Y(s)

Let's say the input is a constant step: r(t) = A. Therefore R(s) = A/s. Also Y(s) = G(s) * R(s). So

y_ss = (lim s-->0) s*G(s) * R(s)
y_ss = (lim s-->0) s*G(s) * A/s
y_ss = (lim s-->0) A * G(s)
y_ss = A*G(0)

Gain is defined in the time domain as the final output value / input value = y_ss / r(t)

gain = A*G(0)/A
gain = G(0)

[howardwang]

How I wish I had watched this video when I was in the university, which might have saved me two years of gaining the same level of understanding! Thank you so much, Brian!!!

[samlnt]

have been scratching my head getting introduced to control system ...this is the perfect video to understand the foundation...a real help for me thanks so much for the way you have explained

[w]

yes. this is the king of explanation. i have been lost on this since my UG days 20 over years ago...it is so well explained. wish my lecturers could do the same.

[eechaze]

One problem with professors in Universities is many of them have little to no professional experience so they just run through the course with out explaining in details like this

[andrewmaksimovich]

This single video taught me more about control systems than my entire summer class

[PunmasterSTP]

What are transfer functions? More like "Wonderful knowledge and instruction!" Thank you so much for sharing.

[rostamr]

I really like and find your video easy to follow and very helpful. Thank you

[Lexyvil]

Thanks. My Electronics 1 professor started using "jw" in his equations and assumed I already knew what those variables meant.

[gerard-nagle]

Not sure what is been done in the 3D plot at the 5:52 time mark, is it the magnitude or just for s=-0.1+0.2j, the values are 0.25+0.75j and so on across the Re-Im plane?

[conall]

You're getting me through my Robot control systems module at university Brian, not all heroes wear capes!

[mehmetkilic]

Looking forward to see more videos Brian :)

[dogukartal]

It helps a lot, Thank you Brian! You are the best.

[stevematson]

Greatly appreciate the lecture. Question: let's say that you have a circuit in a 'black box' and you know it is likely to be represented by a transfer function, but you have no clue as to the circuit, components or values. Can you do a few tests and from the output, figure out what the black box acts like? Like searching for an equivalent circuit.
Thanks in advance.

[OMNI_INFINITY]

Oh oh oh! So basically the 2 numbers output by the transfer function are each mapped to a separate vertical axis to make 2 3D models with the same xy base. (if z is the vertical axis) !!! Thankfully figured that out now. Could have explained that better in the video. No offense.

[OMNI_INFINITY]

*Where is the link to the Laplace movie mentioned in that movie?*