From the principle of dual-channel to the theory of constructing invariant measuring systems

The article presents the theoretical foundations for constructing invariant and quasi-invariant relative to the disturbing influences of measuring systems. A historical reference which shows the emergence, evolution and spread of methods of the theory of invariance from automatic control and regulation systems to information and measuring systems and measurements in general is given. The possibilities of new applications of the formulated by academician B.N. Petrov of the two-channel principle are shown. On its basis, methodological signs of the physical feasibility of structural and technological methods are formulated. Theoretical foundations and the method of linearization of principally nonlinear transformation functions of parametric measuring transducers, which are also based on the principle of two-channel, are given. All theoretical positions are supported by practical examples that extend the capabilities of the considered methods to the entire class of parametric measuring transducers as part of non-equilibrium measuring bridges and voltage dividers.