Stability limits for third-order servomechanisms

IN VIEW of the important, numerous, and rapidly increasing uses of servomechanisms, analytic procedures that facilitate rapid design are of obvious technical value. The prime purpose of this paper is to set out the details of such a procedure. It has two major uses: First, in analysis it affords quick ascertainment of the roots of a specified cubic characteristic equation, thus enabling rapid determination of the stability characteristics of the corresponding third-order servo system; conversely, in synthesis it enables selection of the coefficients of a cubic characteristic equation to the end that a third-order servo system can be formulated with a desired degree and kind of stability.