For those who do not have access to MATLAB, which has now become an industry standard (more or less), this book also provides other digital computer programs for obtaining the Bode diagram. This approach for providing both MATLAB and other digital computer programs which are not dependent on COTS (commercial-off-the-shelf software) is used throughout this book.
The digital computer is a very valuable tool for computing the gain and phase characteristics as a function of frequency [11, 12]. Several program languages can be used to perform this computation. Perhaps the simplest languages are Basic (Beginner’s All-purpose Symbolic Instruction Code) [13, 14] and Fortran (FORmula TRANslator) [13,14]. Several problems are solved in this chapter and in the rest of this book utilizing these languages with working programs provided. Commercially available computer programs for solving control-system problems are presented in Section 6.21. One of these, MATLAB, has been used for the four illustrative problems shown in Section 6.7, and in Section 6.8 which is dedicated to MATLAB.
Consider a unity-feedback control system where
It is desired to determine the phase and gain margins of this linear control system, and a Basic program will be utilized in this problem [13