# Study of Systems of Active Vibration Protection of Navigation Instrument Equipment
###### Abstract
Like active sound absorption systems, active vibration protection methods require the presence of a sensitive element (elements) at a certain point of the vibration field, as well as a system for amplifying and transmitting this information on the way to the emitter. The characteristics of the energy state of the system of active acoustic and vibration isolation are determined by the energy consumption in the converting devices depending on the operating conditions. The active vibration protection system is more effective with a narrower area of space where the vibrational energy from an external source is materialized. A serious limitation of this is the impossibility of broad-band suppression of modulation oscillations. In the case of expanding the operating frequency, conditions for positive feedback arise and, as a result, the stability of the system as a whole is lost or local self-excitation is created. A comparative analysis shows that the technical implementation of active vibration protection is more complex than acoustic, due to the occurrence of various types of vibrations in solid-state structures, i.e., bending, longitudinal, shear, etc., which leads to the need to introduce additional receivers and emitters into the vibration protection system's sound. The article investigates one of the main elements of measuring elements in vibration protection and vibration reproduction systems, which is elastic suspension. Suspension on flat springs is most often used, a feature of which is the practical absence of relative angular rotation and relative translational movement of suspension parts, as well as the practical absence of dry friction. When using an elastic suspension in the form of an inverted pendulum on vertically located and cantilever-fixed flat springs, it is possible to obtain a natural frequency of the suspension in the horizontal plane of about 1 Hz. The high kinematic selectivity of such a suspension regarding the direction of the measured or reproduced vibration and the possibility of achieving relatively low natural frequencies make it promising from the point of view of use for many practical tasks. The obtained research results can be of practical importance for the vibration isolation of navigation equipment in the area of low disturbance frequencies. Research on reducing the natural frequency of elastic suspension will allow an increase in the accuracy of existing measuring elements in vibration protection systems, as well as reduction in the dimensionsof such systems and improvement in the quality characteristics of instrumentation, in particular, the accuracy of navigational geophysical devices. This research consists in the development of a system of active protection of ground-based navigation instrumentation equipment from vibration, as well as in the justification of the choice of feedback parameters. The dynamics and effectiveness are investigated of the active vibration isolator and methods developed for calculating the elastic suspension and the executive mechanism. The purpose of the study is to improve the accuracy of navigation instrumentation installed on a limited movable base. For the set goal, it is planned to create a system of active protection against translational vibration in the horizontal plane with the estimated efficiency of vibration isolation of the instrument equipment in the frequency range of 0.8,..., 5 Hz--10,..., -12 dB. This range is the most dangerous, from the point of view of measurement error, and the natural frequency of the pendulum gyrocompass is 1,..., 2 Hz. Vibrational external disturbances also belong to the studied frequency range.