The gyrotachometer is designed to measure the angular velocity of rotation of a movable base around one of the axes, which is called the input or measuring axis. The problem is reduced to solving a linear differential equation with constant coefficients. However, the gyrotachometer reacts to rotation around other axes of the bases, the so-called extraneous ones. At the same time, constant, or rather, slowly changing deviations or deviations are observed, which cannot be explained in any way by the properties of a linear equation with constant coefficients.

The accuracy of the solutions obtained by any of the known approximate methods depends on how well the functions approximating this solution are chosen. It is natural to expect that, while maintaining the desired solution in the expansion series, even the minimum number of terms of the series (and it is this case that is of the greatest interest for practical calculations), the approximate solution will differ insignificantly from the exact one if the approximating functions satisfy all boundary conditions...

In many cases, especially for systems of high order, when solutions of differential equations and algebraic stability criteria become very cumbersome, frequency study is more convenient and illustrative, especially in those cases, when for some links of the automatic system, easily amenable to modeling, it is easier to experimentally remove the frequency characteristics than to make differential equations of dynamics.