Who developed Root Locus Analysis and in what year?

• A. Nyquist, 1932
• B. Walter Evans, 1948
• C. Bode, 1956
• D. Routh, 1877

Answer: (B)

Root Locus Analysis is a significant technique in control theory used to analyze the stability and response of feedback control systems. Walter Evans developed this method in 1948 as part of his work on control systems. The root locus technique helps engineers visualize how the roots of a system's characteristic equation move in the complex plane as system parameters (such as feedback gain) change. This insight is crucial for determining how changes to system configurations affect stability and performance.

Other figures mentioned, like Nyquist and Bode, contributed valuable theories and methods in control systems and signal processing, such as the Nyquist stability criterion and Bode plots, but they are not connected with the development of Root Locus Analysis. Routh's work, while influential in developing the Routh-Hurwitz criterion for stability analysis, predates Root Locus Analysis by several decades. Thus, 1948 and Walter Evans stand out as the correct reference for the roots of this analytical method.