Isodromic Governor

Governor, Isodromic


(also floating control element; in Russian, izodrom), a device that provides transient feedback in controllers. It is a mechanism consisting of a damper, a spring, and a system of levers, or it is a differential circuit that is connected to a negative feedback loop.

The term “isodromic” was originally applied to centrifugal controllers, in which such a governor maintains a constant speed of rotation of a machine under various loads. Upon a change in load (for example, an increase), the speed of rotation of the engine decreases, the sleeve of the regulator actuates a servomotor by means of a slide valve, and the piston of the servomotor drops, together with the damper cylinder. Under the action of a spring, the piston of the damper is displaced upward with respect to the cylinder, and the total feedback length increases, leading to a stable displacement of the throttle, which regulates the supply of fuel or steam to the engine, and the speed of rotation of the engine is stabilized. The rate of displacement of the piston relative to the damper cylinder may be controlled.

Isodromic governors are characterized by the isodrome time, during which the governing element, which was previously displaced by 1 percent of its stroke, is displaced by an additional 1 percent as a result of the action of the isodrome component. The isodrome time of isodromic governors may be adjusted from 3 sec to 100 min.


Voronov, A. A. Osnovy teorii avtomaticheskogo upravleniia, part 1. Moscow-Leningrad, 1965.
Aizerman, M. A. Teoriia avtomaticheskogo regulirovaniia, 3rd ed. Moscow, 1966.


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