This is the second part of how to sketch a root locus by hand. However instead of following the normal rules for sketching a locus that you'd see in a book, I decided to explain the rules how I use them, and how knowledge of the shape of a root locus can help you design a compensator. 

You can check out the math behind these rules from this online book. If you Google for it you can read the book for free through Google Books. Control System Principles and Design by Ernest O. Doebelin -- Starting at Page 305

Of course if you're looking for more of a classroom style lecture than you really can't go wrong with Prof. Madan Gopal at nptelhrd.http://www.youtube.com/watch?v=oA4JRc... 

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