Feedback control systems with dead-time lag or distributed lag by root-locus method

A FEEDBACK control system is composed of a group of elements, which may be electrical, hydraulic, pneumatic, and so forth, whose behavior may be linear or nonlinear. The analysis and synthesis of a feedback control system with linear elements which can be described by a linear differential equation with constant coefficients have been well developed. In such analysis and synthesis, the term "transfer function"
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frequently is employed to describe a servo element. It is a Laplace transform notation of the differential equation governing the behavior of the element.