From follett at ece.msstate.edu Fri Dec 4 12:01:14 2009 From: follett at ece.msstate.edu (Randolph F. Follett) Date: Fri Dec 4 12:00:01 2009 Subject: [ece4913] ECE 4913/6913 - Announcements Message-ID: <7.0.1.0.2.20091204114923.06c57740@ece.msstate.edu> I will be in my office this afternoon from about 1:00 until at least 4:00. If you would like to get your 3rd quiz at that time, I will be glad to give it back to you, as well as to answer any questions about it. It was pointed out to me last night that there is a discrepancy in the cited results from Problem 2 on the 3rd quiz. In spite of the claim that the design worked, if you check the closed-loop transfer function, and find the roots of the denominator (the system characteristic equation), you will find that there is one pole in the right half plane. This threw me for a bit, until I realized that when I had done the frequency response and looked at the Nyquist diagram, I had been careless. The fact that there is a negative sign attached to the compensator (as shown in the second form of the compensator in the quiz solution) causes a change in the infinite semicircle, resulting in an unstable system. (At least, I believe that is the essence of the problem. I have not checked out the "gory details" of the analysis yet.) This does not change the design equations, or any of the results on the quiz, but it does once again point out the problems associated with using a non-minimum phase compensator (or an unstable one). With regard to the MATLAB assignment, you will NOT need to address this issue with the example problem. For the purposes of the assignment, you can simply accept the results of the margin command and show the Nyquist diagram without worrying about the sign change. If I can come up with a concise and simple enough explanation of the details of the problem, I will let you know, but you will not be expected to address this issue on the exam. As always, let me know if you have any questions regarding any of this. Randy Follett ----------------------------------------------------------------------------------------- Randolph F. Follett, Ph.D., P.E. Assistant Professor Department of Electrical and Computer Engineering Mississippi State University Box 9571 406 Hardy Rd Office: 662-325-3073 Mississippi State, MS 39762-9571 FAX: 662-325-2298 e-mail: follett@ece.msstate.edu ------------------------------------------------------------------------------------------ From follett at ece.msstate.edu Fri Dec 4 12:13:21 2009 From: follett at ece.msstate.edu (Randolph F. Follett) Date: Fri Dec 4 12:12:07 2009 Subject: [ece4913] Re: ECE 4913/6913 - Announcements (updated) In-Reply-To: <7.0.1.0.2.20091204114923.06c57740@ece.msstate.edu> References: <7.0.1.0.2.20091204114923.06c57740@ece.msstate.edu> Message-ID: <7.0.1.0.2.20091204120739.06c575f8@ece.msstate.edu> Just after sending this past e-mail, I suddenly realized what had actually happened on the Nyquist analysis. If I had done all the steps (as I have mentioned is very important) I would have realized that the unstable pole in the compensator actually counts towards the calculation of P in the equation Z = N + P. There are no unstable poles of GH(s), which makes P = 0 in the uncompensated phase, but when the compensator is included, P becomes 1, resulting in Z = 1, and the system is unstable. In order for this to actually work, there would have had to be a counterclockwise encirclement of the -1 point to counteract the P = 1. I again apologize for this confusion, and hope that this finally clears up the issue. For the purposes of the MATLAB assignment, you can go ahead and make note of the fact that the resulting Nyquist analysis shows that the system is unstable. This does not change any of the design equations or the results of application of the design technique for that system. It just points out that the user does need to be aware of the details of the process. Randy Follett At 12:01 PM 12/4/2009, Randolph F. Follett wrote: >I will be in my office this afternoon from about 1:00 until at least >4:00. If you would like to get your 3rd quiz at that time, I will be >glad to give it back to you, as well as to answer any questions >about it. > >It was pointed out to me last night that there is a discrepancy >in the cited results from Problem 2 on the 3rd quiz. In spite of >the claim that the design worked, if you check the closed-loop >transfer function, and find the roots of the denominator (the >system characteristic equation), you will find that there is one >pole in the right half plane. This threw me for a bit, until I >realized that when I had done the frequency response and looked >at the Nyquist diagram, I had been careless. The fact that there >is a negative sign attached to the compensator (as shown in the >second form of the compensator in the quiz solution) causes a >change in the infinite semicircle, resulting in an unstable system. >(At least, I believe that is the essence of the problem. I have not >checked out the "gory details" of the analysis yet.) This does >not change the design equations, or any of the results on the >quiz, but it does once again point out the problems associated >with using a non-minimum phase compensator (or an unstable >one). > >With regard to the MATLAB assignment, you will NOT need to >address this issue with the example problem. For the purposes >of the assignment, you can simply accept the results of the >margin command and show the Nyquist diagram without worrying >about the sign change. If I can come up with a concise and >simple enough explanation of the details of the problem, I will >let you know, but you will not be expected to address this issue >on the exam. > >As always, let me know if you have any questions regarding any >of this. > >Randy Follett > > > > > > > >----------------------------------------------------------------------------------------- > >Randolph F. Follett, Ph.D., P.E. >Assistant Professor >Department of Electrical and Computer Engineering >Mississippi State University > >Box 9571 >406 Hardy Rd Office: 662-325-3073 >Mississippi State, MS 39762-9571 FAX: 662-325-2298 > >e-mail: follett@ece.msstate.edu > >------------------------------------------------------------------------------------------ > ----------------------------------------------------------------------------------------- Randolph F. Follett, Ph.D., P.E. Assistant Professor Department of Electrical and Computer Engineering Mississippi State University Box 9571 406 Hardy Rd Office: 662-325-3073 Mississippi State, MS 39762-9571 FAX: 662-325-2298 e-mail: follett@ece.msstate.edu ------------------------------------------------------------------------------------------ From follett at ece.msstate.edu Sat Dec 5 18:24:56 2009 From: follett at ece.msstate.edu (Randolph F. Follett) Date: Sat Dec 5 18:24:04 2009 Subject: [ece4913] ECE 4913 - Homework/Review Session? Message-ID: <7.0.1.0.2.20091205182233.08521cb8@ece.msstate.edu> I have only had a couple of people ask questions regarding any of the material for the Controls I final exam next Wednesday. So, the first question I should ask is whether you are interested in having a study session. Secondly, if you are interested, would you rather have it Monday afternoon ----------------------------------------------------------------------------------------- Randolph F. Follett, Ph.D., P.E. Assistant Professor Department of Electrical and Computer Engineering Mississippi State University Box 9571 406 Hardy Rd Office: 662-325-3073 Mississippi State, MS 39762-9571 FAX: 662-325-2298 e-mail: follett@ece.msstate.edu ------------------------------------------------------------------------------------------ From follett at ece.msstate.edu Sat Dec 5 18:27:20 2009 From: follett at ece.msstate.edu (Randolph F. Follett) Date: Sat Dec 5 18:26:07 2009 Subject: [ece4913] Re: ECE 4913 - Homework/Review Session? In-Reply-To: <7.0.1.0.2.20091205182233.08521cb8@ece.msstate.edu> References: <7.0.1.0.2.20091205182233.08521cb8@ece.msstate.edu> Message-ID: <7.0.1.0.2.20091205182536.085221d8@ece.msstate.edu> Sorry, somehow the e-mail got sent before I finished it... At 06:24 PM 12/5/2009, Randolph F. Follett wrote: >I have only had a couple of people ask questions regarding any >of the material for the Controls I final exam next Wednesday. >So, the first question I should ask is whether you are interested >in having a study session. Secondly, if you are interested, would >you rather have it Monday afternoon ...(between 3:00 p.m. and 5:00 p.m.) or sometime Tuesday evening? Please respond to the question as to whether you are interested, and if you answer yes to that, indicate a preference on the time. Thanks, Randy Follett >----------------------------------------------------------------------------------------- > >Randolph F. Follett, Ph.D., P.E. >Assistant Professor >Department of Electrical and Computer Engineering >Mississippi State University > >Box 9571 >406 Hardy Rd Office: 662-325-3073 >Mississippi State, MS 39762-9571 FAX: 662-325-2298 > >e-mail: follett@ece.msstate.edu > >------------------------------------------------------------------------------------------ ----------------------------------------------------------------------------------------- Randolph F. Follett, Ph.D., P.E. Assistant Professor Department of Electrical and Computer Engineering Mississippi State University Box 9571 406 Hardy Rd Office: 662-325-3073 Mississippi State, MS 39762-9571 FAX: 662-325-2298 e-mail: follett@ece.msstate.edu ------------------------------------------------------------------------------------------ From follett at ece.msstate.edu Mon Dec 7 10:00:48 2009 From: follett at ece.msstate.edu (Randolph F. Follett) Date: Mon Dec 7 09:59:20 2009 Subject: [ece4913] ECE 4913/6913 - Homework/Problem session Message-ID: <7.0.1.0.2.20091207095816.0761b0a0@ece.msstate.edu> Based on the responses so far, (very few, by the way), we will have a problem session tomorrow, beginning at 5:00 p.m. Let me know if you are going to be in an exam at that time (if you are planning to attend the problem session) and we can shift it to a little bit later. I will not be available much today, but if you have any questions, let me know. If need be, I can be here some this afternoon. I am not available this morning, however, except through e-mail. Randy Follett ----------------------------------------------------------------------------------------- Randolph F. Follett, Ph.D., P.E. Assistant Professor Department of Electrical and Computer Engineering Mississippi State University Box 9571 406 Hardy Rd Office: 662-325-3073 Mississippi State, MS 39762-9571 FAX: 662-325-2298 e-mail: follett@ece.msstate.edu ------------------------------------------------------------------------------------------ From follett at ece.msstate.edu Tue Dec 8 12:26:44 2009 From: follett at ece.msstate.edu (Randolph F. Follett) Date: Tue Dec 8 12:25:07 2009 Subject: [ece4913] ECE 4913/6913 - Reminders Message-ID: <7.0.1.0.2.20091208122042.077cd8f8@ece.msstate.edu> As mentioned in a recent e-mail, we will have a problem session this evening beginning at 5:00 p.m. After checking the schedule, it appears that our normal classroom will be available, so we will plan to meet there. The problem session will last no more than 2 hours. Also, remember that all lab reports and MATLAB projects are due BEFORE the exam begins tomorrow at 12:00 p.m. The exam is open-book, open-notes, closed-neighbor, as has been the case for each of the quizzes through the semester. Randy Follett ----------------------------------------------------------------------------------------- Randolph F. Follett, Ph.D., P.E. Assistant Professor Department of Electrical and Computer Engineering Mississippi State University Box 9571 406 Hardy Rd Office: 662-325-3073 Mississippi State, MS 39762-9571 FAX: 662-325-2298 e-mail: follett@ece.msstate.edu ------------------------------------------------------------------------------------------ From follett at ece.msstate.edu Tue Dec 8 13:00:41 2009 From: follett at ece.msstate.edu (Randolph F. Follett) Date: Tue Dec 8 12:59:04 2009 Subject: [ece4913] Re: ECE 4913/6913 - Reminders - CHANGED! In-Reply-To: <7.0.1.0.2.20091208122042.077cd8f8@ece.msstate.edu> References: <7.0.1.0.2.20091208122042.077cd8f8@ece.msstate.edu> Message-ID: <7.0.1.0.2.20091208125906.077cdcd0@ece.msstate.edu> Due to unforeseen circumstances, I will have to move the problem session to 6:00 tonight. I apologize for the inconvenience, as well as the late notice, but I will not be available at 5:00 unfortunately. I'll see you at 6:00 in the regular classroom (if you are interested). Randy Follett At 12:26 PM 12/8/2009, Randolph F. Follett wrote: >As mentioned in a recent e-mail, we will have a problem session >this evening beginning at 5:00 p.m. After checking the schedule, >it appears that our normal classroom will be available, so we will >plan to meet there. The problem session will last no more than 2 >hours. Also, remember that all lab reports and MATLAB projects >are due BEFORE the exam begins tomorrow at 12:00 p.m. >The exam is open-book, open-notes, closed-neighbor, as has >been the case for each of the quizzes through the semester. > >Randy Follett > > > > >----------------------------------------------------------------------------------------- > >Randolph F. Follett, Ph.D., P.E. >Assistant Professor >Department of Electrical and Computer Engineering >Mississippi State University > >Box 9571 >406 Hardy Rd Office: 662-325-3073 >Mississippi State, MS 39762-9571 FAX: 662-325-2298 > >e-mail: follett@ece.msstate.edu > >------------------------------------------------------------------------------------------ > ----------------------------------------------------------------------------------------- Randolph F. Follett, Ph.D., P.E. Assistant Professor Department of Electrical and Computer Engineering Mississippi State University Box 9571 406 Hardy Rd Office: 662-325-3073 Mississippi State, MS 39762-9571 FAX: 662-325-2298 e-mail: follett@ece.msstate.edu ------------------------------------------------------------------------------------------ From follett at ece.msstate.edu Tue Dec 8 13:13:40 2009 From: follett at ece.msstate.edu (Randolph F. Follett) Date: Tue Dec 8 13:12:02 2009 Subject: [ece4913] Re: ECE 4913/6913 - Reminders - CHANGED! (AGAIN) In-Reply-To: <7.0.1.0.2.20091208125906.077cdcd0@ece.msstate.edu> References: <7.0.1.0.2.20091208122042.077cd8f8@ece.msstate.edu> <7.0.1.0.2.20091208125906.077cdcd0@ece.msstate.edu> Message-ID: <7.0.1.0.2.20091208131306.077ce0a8@ece.msstate.edu> I meant to say 6:30, not 6:00. Sorry for the added confusion. Randy Follett At 01:00 PM 12/8/2009, Randolph F. Follett wrote: >Due to unforeseen circumstances, I will have to move the problem >session to 6:00 tonight. I apologize for the inconvenience, as well >as the late notice, but I will not be available at 5:00 unfortunately. >I'll see you at 6:00 in the regular classroom (if you are interested). > >Randy Follett > > >At 12:26 PM 12/8/2009, Randolph F. Follett wrote: >>As mentioned in a recent e-mail, we will have a problem session >>this evening beginning at 5:00 p.m. After checking the schedule, >>it appears that our normal classroom will be available, so we will >>plan to meet there. The problem session will last no more than 2 >>hours. Also, remember that all lab reports and MATLAB projects >>are due BEFORE the exam begins tomorrow at 12:00 p.m. >>The exam is open-book, open-notes, closed-neighbor, as has >>been the case for each of the quizzes through the semester. >> >>Randy Follett >> >> >> >> >>----------------------------------------------------------------------------------------- >> >>Randolph F. Follett, Ph.D., P.E. >>Assistant Professor >>Department of Electrical and Computer Engineering >>Mississippi State University >> >>Box 9571 >>406 Hardy Rd Office: 662-325-3073 >>Mississippi State, MS 39762-9571 FAX: 662-325-2298 >> >>e-mail: follett@ece.msstate.edu >> >>------------------------------------------------------------------------------------------ > >----------------------------------------------------------------------------------------- > >Randolph F. Follett, Ph.D., P.E. >Assistant Professor >Department of Electrical and Computer Engineering >Mississippi State University > >Box 9571 >406 Hardy Rd Office: 662-325-3073 >Mississippi State, MS 39762-9571 FAX: 662-325-2298 > >e-mail: follett@ece.msstate.edu > >------------------------------------------------------------------------------------------ > ----------------------------------------------------------------------------------------- Randolph F. Follett, Ph.D., P.E. Assistant Professor Department of Electrical and Computer Engineering Mississippi State University Box 9571 406 Hardy Rd Office: 662-325-3073 Mississippi State, MS 39762-9571 FAX: 662-325-2298 e-mail: follett@ece.msstate.edu ------------------------------------------------------------------------------------------