Stellar Course Management System

Practice problem solution errata

Dear all,

Some errors have been brought to my attention in the practice problem solutions. (These were due to changes between editions of Nise that I failed to catch in the course of going through 29 problems and solutions.)

Specifically in 8.7 and 8.9:

- 8.7 appears to have a different pole-zero plot in the current (4th) edition compared to the posted solution, so the posted solution does not make sense (although it does for the poles and zeros shown in the solution itself!). The point of this problem was simply that the RL starts at the poles and goes toward the zeros of the open-loop TF and must be symmetric about the real axis, which gives a limited number
of options for what it can look like.

- 8.9 had a different transfer function between editions ( G(s) = K(s^2-1)/(s^2+1) in the answer-key edition).
For the current edition, with G(s) = K(s^2-9)/(s^2+4), the poles are at +/-3 and zeros at +/-2j. Qualitatively the root-locus plot looks the same in both cases. With these poles and zeros, K>(4/9) is required for (marginal) stability (rather than K>1 as in the posted solution).

Apologies for any confusion caused by this oversight.

Ariel

Announced on 24 May 2006  11:51  p.m. by Ariel Herrmann

Last-minute pre-exam notes

In response to a number of recent inquiries from class members in the lead-up to the exam, I'd like to offer the following notes and clarifications to keep everyone on equal footing leading up to the exam:

* Reading on root locus and Bode plots:
- Nise 8.1-8.7 (as posted in class) goes over root locus to the extent covered in class. You may need to do some calculations of the sort covered in lectures and in these sections of Nise.
- Nise 10.1-10.2 covers Bode plots.

There is no explicit required reading other than what has been mentioned in class. Note, however, that material in lab handouts, Prof. Rowell's handouts on linear graphs, etc. may be fair game, as mentioned in class.

* Polar plots, Routh tables:
These exciting topics will NOT be covered on the exam, as they were not covered in class and as Prof. Rowell explicitly mentioned that you should not bother with the latter.

* Bode plots sketching by hand:
You may need to sketch some Bode plots by hand, and to do some simple back-and-forth between Bode plots and transfer functions as mentioned in the review outline in class last Wednesday.
See Nise Ch.10 (10.1-10.2, as mentioned above) for simple rules to sketch Bode plots.

Please note that none of the above constitutes an explicit guarantee that a certain topic will be on the exam, and that the simple omission of a topic here does not guarantee its exclusion from the exam (which I have not seen). These notes come as a result of questions from class members, and are being sent to all for the sake of fairness.

Best wishes for effective studying,

Ariel

Announced on 24 May 2006  11:10  p.m. by Ariel Herrmann

Review problem solutions posted on Stellar

All,

Selected solutions to problems from Nise have been posted in the Materials section of the course web site to help with final-exam review.

The problems are as follows (chapter.problem numbers) -

2.7, 10, 16, 26, 52
3.9, 14
4.2, 8, 14, 15, 26, 27
5.4, 7, 12
7.1, 2, 3, 22, 23, 24, 48
8.2, 7, 9, 21
10.24, 27

I've selected these problems to cover a range of the
material from the course. I can't guarantee comprehensive coverage (especially as Nise doesn't have linear graphs for
instance) but have tried my best to touch as many of the bases as possible and hope you might find them useful in studying and review.

Ariel

Announced on 22 May 2006  4:11  p.m. by Ariel Herrmann

Review Session Friday 2PM

With class over but finals starting Monday, tomorrow seems the best time for a final review session. Since this is going out late, feel free to sleep in a while -- join me from 2-3PM in 1-190.

I'll go over the course outline in some more detail, work some problems, and will be available to answer questions on any course material.

Practice problems to help study for the final will be posted tomorrow as well.

Cheers,

Ariel

Announced on 18 May 2006  10:07  p.m. by Ariel Herrmann

Important 2.004 Reminder!

All,

Here's a reminder re. the online course survey for 2.004. Please take note!

*** REMINDER ***

(1) EVERYONE WHO FILLS OUT THE SURVEY WILL RECEIVE FULL CREDIT (10 POINTS) FOR PROBLEM SET 9. EVERYONE WHO DOES NOT WILL RECEIVE NO CREDIT FOR PROBLEM SET 9.

(2) The survey closes on 5/18, i.e. TOMORROW.

(3) The URL for the survey is given below.

http://web.mit.edu/surveys/subjecteval/

You may note that there's no place to enter your name on the survey and the responses are kept anonymous. MIT certificates are needed to access the survey, however, so we can still keep track of who gets credit.

Ariel

Announced on 17 May 2006  7:54  p.m. by Ariel Herrmann