何毓琦的个人博客分享 http://blog.sciencenet.cn/u/何毓琦 哈佛(1961-2001) 清华(2001-date)

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Education of a Control Engineer. 精选

已有 8586 次阅读 2015-7-16 22:24 |系统分类:教学心得

 

 

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26 years ago when I received the highest award of the IEEEControl System Society, The Control Engineering and Science Field Award,  I gave the following acceptance speech. Re-reading it more than  two decades later, I still feel the same way. I post it here to share  with Science Net readers.

 

 

EDUCATION OF A CONTROL ENGINEER

-LESSONS I HAVE LEARNED-

 

Remarks by

Y.C.Ho

On accepting the IEEE Control Engineering and Science  Field Award at the 28th  Conference on  Decision andcontrol

December 14,1989 Tampa,Florida

 

 

It is the tradition on this occasion for the recipient to say something  about the history and the future of the field which is represented by this award. The six illustrious previous recipients of this award before me have very thoroughly reviewed the  history of our Society and the award. I doubt that I have anything  useful to add or subtract. As for the future, I am always reminded of the story about Professor Howard Aileen,the father  of modem digital computers. I spent half of my professional  life in the laboratory that bears his name. In 1948, Time  Magazine  did  a cover article about the onset of the computer age and interviewed Professor Aiken. He had just finished building the Mark IV series of computers (note1).The reporter wanted to know how many of  these Mark IV computers would eventually be needed  by the world.  Aiken thought about it and replied "Oh, maybe ten". So much for  predicting future. Now this leaves me only with personal reminiscences. Of course, I could talk about how Kalman, Narendra, and I got together and wrote the controllability  paper, or let you guess who wrote what part in the book  Applied Optimal Control. But that is the same as foisting your  home vacation slides on your dinner guests.  What is interesting and memorable to me personally is not necessarily  suitable material for public consumption.

 

Instead let me share some of the lessons I learned  in the past   29 years (1960-1989) with you. They may be of interest  particularly to young engineers in the audience who are just starting out in the business.In this connection I am reminded of last year's bestseller"All I really need to know I learned in  Kindergarten " (note 2). While that may very well be true,  I am a much slower learner. Looking back, I did not even begin learning useful lessons until the senior year in college and I am  still learning to this date.

 

At one time in the 50's at MIT's EE department, the gospel  was that there were only two   books any electrical engineer needed to know.Symthe's "Static and DynamicElectricity" for the physically oriented and Bode's  "Feedback Amplifier Design"  for the mathematicians. In my senior year I registered for a course on high gain lowdrift DCamplifier design. I don't know how many of you in this  room still remember the 400 cps chopper-stabilized DC vacuum  tube feedback amplifiers.  Designing those things is enough to drive one mad with frustration. Thinking  that reading Bode  would be beneficial, I tried without any success to understand  the  book even  thoughit was extremely well written.  Then and there, I learned the gap between theory and  practice.  At any given time, the most sophisticated theory  always has very little to do with the most advanced applications.

My second lesson began when I went to work in industry for  the Bendix  Aviation  Corp. At the time I had Brown and Campbell, and Newton,Gould & Kaiser (note 3)  under my belt.I was all set to design  servomechanisms. Instead , I was told to learn all about digital computers because my boss (note4) needed me to design logical circuits for numerical control. I knew nothing  about digital computers, switching theory, transistors and  magnetic cores. But I found out what a good education  prepares you to do. It teaches you how to think for yourself and learn on your own. What I  learned and did in12 months (four patents resulted)  were a lot more than several courses put together.

 

My 3rd lesson began when I came back to Harvard- I learned the wonders and magic of applying mathematics in engineering.  This essentially determined my work for the rest of my professional life. The works that influenced me included the early preprints of Kalman who was happy to sent them to anyone who asked for them, a draft copy of "adaptive control - a guided tour" by Bellman lent to me by my classmate, S. Dreyfus who  was then programming for Bellman. I was also fortunate to  be in the class the first time Bill Root taught  Davenport & Root in book form. As the classic 50's song says, those were the days!

 

The early 60's gave me my fourth lesson- The limitation of  mathematics in engineering. I owe this to the tutelage of Arthur E. Bryson, Jr. and Lotfi Zadeh. Some physicists take the  position that  it is not physics if it cannot be tested and validated.I came to appreciate that it is not engineering if it cannot be put into practice and that an"exercise left to the reader" is often the difference between success and failure of an engineering  endeavor. Of course, this is a two edged sword. What is "intuitively obvious" to an engineer may require months of hard work  by a mathematician to prove or, even more importantly, to disprove.

The following assertions and beliefs I hold dear to my heart:

a.  Good ideas often come from real problems. Necessity IS  the mother ofinvention.

b.  Good ideas are often conceptually simple once thoroughly understood. One should take the position that it is possible to explain anything to anybody in any amount of allotted time at the level they can omprehend.

c.   If you make a sincere commitment to work on a real problem rather than a commitment to use a particular technique,something good and interesting always comes out of it in the end.

d. You can learn anything in six months to suit your  purpose. What looks formidable at a distance becomes far less so once you get into it. Thus, by all means dive into  new fields. It is far easier to pick up loose nuggets  lying on the surface than to dig deep into a mine worked out by someelse.

 

My personal experiences whether they were with differential games, (the result of studying proportional navigation law and  dog fight ,1966), team decision analysis (understanding the question who knows what when, and the second guessing paradox, 1970), incentive control (from time-of-day electricity pricing,  1979), or PA and DEDS (from a real  manufacturing problem,1977) certainly reinforce these beliefs.

After almost 3 decades, I am still learning.This is the greatest joy of an academic career.You never stop or want to stop learning. Looking back, I realize "I am a lucky guy" (note 5)  .Without   the love and total supportof my parents, family,  and particularly, my wife of 30 years , I surely would not be here tonight.The many good friends, colleagues, and my 37  former Ph.D.students in the field have all taught me much more than I taught them. Above all,on occasions when I became lazy or sloppy, they were the ones who kept me honest. My whole  career is essentially spent working for one institution  which represents the best example of American  private higher education; I thank Harvard University for the standard she inspires and the freedom she gives to young faculty members.  But in this holiday season of   thanksgiving and  particularly in such an eventful year in world affairs as this, one entity symbolizes all the good things I am  thankful for. It is old fashioned and may be chauvinistic to  say this in such an international setting, but I say it  with sincerity and all the gratitude  that only an immigrant is privileged to feel about his adopted country -  "Thank you, the United States  of America, for the freedom and opportunities you give to your citizens". Good evening and happy holidays.

 

 

Reference notes

1. which had less memory than one of those $500 TI  programmable calculators nowadays carried around by high  school students.

2. Robert Flughum,Random House1988.

3.Two best known control texts at that time.

4.Dr. E. Calvin Johnsonof the describing function fame.

5. Phrase made popularby the comedian, SteveMartin.




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