ENB458 lecture 1: Introduction to digital control

QUT ENB458 Advanced control, Lecture 7 - Introduction to digital control.

In this lecture we discuss why it makes sense to use a computer to implement a control system, a digital control system.

[PeterCorke]

Because we're trying to make a link between Laplace and discrete-time domain.  There are lots of ways to treat this, I was trying to use a line of reasoning that was simple and intuitive (to me).

[PeterCorke]

Iftikhar, when you discretise a plant you need to know the sample interval so that the dynamics of the discrete and continuous systems are matched.  If you change the sample interval then the dynamics of the discrete time system no longer match.

You recall that one way of mapping between continuous and discrete is the matched transform

z = e^(sT)

Flip that around

s  = (log z)/T

You're using the same discrete model so z stays the same, but you are reducing T, so the effective continuous dynamics correspond to a system with larger poles, a "faster" system.

So you are using your controller with a different plant, a faster one, which is why you get the results you do.

[vinaybhaskarchandratre]

for consistency of notation as discussed @ 40:37 F()--> f() ?

[aramnasser]

This is great :)
I'm a mechatronics engineer and I'm so interested in your lectures
but where can I get the previous lectures about advanced control ?

[حساميونس-ثب]

Sir, can you post the first part of this course ?

[PeterCorke]

Sorry, but there's only a few lectures in this series online.  I haven't taught the unit since 2012.