Re: Good controls/signals text

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All,

Thanks for the recommendations, but the answers were not quite what I
was looking for. I think I didn't ask the question correctly. Let me
start again.

I'm considering writing a hypertext control  / linear systems /
dynamics "text". As you know, the subject is fairly involved and
depends on a significant volume of mathematics: differential
equations, complex variables, linear algebra, transform / distribution
theory, and physics. There's really no obvious way to introduce all
these subjects to the beginning student (unlike, say calculus, which
has a pretty standard pedagogical hierarchy of e.g. functions, limits,
derivatives, integrals). As a result, most texts simply introduce the
Laplace transform out of nowhere, then try to convince the student how
useful it is. My idea is to better motivate the subject by introducing
the concept that complex exponentials are the eigenfunctions of LTI
systems, along with the analogy between signals and (infinite
dimensional) vectors (after discussing what eigenvectors and
eigenvalues are for matricies). Hence I think the Laplace transform is
nothing more than the dot product of a signal (or system) with the
complex exponential basis function. The Shaum's outline book of
Signals and Systems has some of this view. Siebert's Circuits Signals
and Systems (my prof way back when) also has some of this flavor in an
appendix, but neither book quite goes into sufficient detail. (BTW I
think the hyper linked format will work nicely to allow the student to
bring in the math as necessary.) Anyway, I'm looking for a treatment
with this "vector space" emphasis. I think, if done correctly, that
this approach might have a more intuitive feel.

Here's an example of the kind of thing I'm going for. Have you noticed
that most linear algebra (and controls) texts define the determinant
of a matrix by the procedure used to compute it, without ever really
mentioning what it IS. If you view the matrix equation y = Ax as an n-
dimensional transformation from the "x" space to the "y" space, the
determinant is just the ratio of n-dimensional volume or area between
the two spaces. That's my concept - to provide an intuitive (if not
necessarily mathematically rigorous) explanation of what things "are",
rather than just how to calculate them.

Thanks again.
Roy

Re: Good controls/signals text



Roy wrote:

If you can do it, and end up with something that is comprehensible to
the average undergraduate, then more power to you.

The textbook that I have that comes closest to that is Harry VanTrees
"Detection and Estimation Theory".  It doesn't go into the Laplace
transform as you mention, but it provides all the foundation that I need
to immediately see where you're coming from.  It is also the text from
the single most difficult class that I have ever taken (when the prof
tells a dozen really bright grad students "you'll pull together and I'll
give 12 A's, or you won't and I'll give 12 D's", and ends up being
right, you know it's a hard class).

So I can certainly see the value of it, if you make it fly.  (In fact, I
want to read it, if you can make it fly).

Something that you may want to consider as you launch into this: my
introduction to control theory came as part of a program that put
control theory _after_ you had taken a comprehensive course in signals
and systems (good ol' Oppenheimer, Willsky & Young).  So while the text
introduced the Laplace transform, we just skipped that part.  I suspect
that most controls texts are taught in that sort of environment, where
the student is assumed to have been introduced to the LT already, and it
is only included in the book in case the student parachuted into the
program from a different planet.

So you may go to all that effort, and have it ignored anyway.

--

Tim Wescott
Wescott Design Services
http://www.wescottdesign.com

Do you need to implement control loops in software?
"Applied Control Theory for Embedded Systems" gives you just what it says.
See details at http://www.wescottdesign.com/actfes/actfes.html

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