# Study of Systems of Active Vibration Protection of Navigation Instrument Equipment
###### Abstract
Reducing the transmission of vibration from the machine to its supporting structure has been the subject of considerable research [24; 25; 26; 27], including research into active, semi-active and passive control [28]. Practical control systems are usually implemented using digital filters and control algorithms formulated in the time domain; the perturbations being monitored are in many cases periodic. The direct control algorithm in the frequency domain was first applied to the problem of four active isolators between a vertically vibrating solid body and a flexible plate clamped at the edge [29; 30]. The effectiveness of the insulation and the predicted value of the control forces were investigated by the finite element method. The analysis for many excitation forces and different types of support structures was carried out using modal analysis [31; 32; 33]. In article [15], the authors studied the influence of the elastic element geometry on the natural frequency of the vibration isolator. The results showed that changing the shape and size of the elastic element can significantly affect the natural frequency of the vibration isolator. In [16], the authors investigated the influence of geometrical parameters of vibration isolators on their dynamic characteristics, demonstrating that the geometric parameters of these vibration isolators, such as wire diameter, length, number of wires, and their relative placement, can affect the dynamic characteristics. In article [17], the authors investigated the influence of the shape of the elastic element on the dynamic characteristics of the vibration isolator. The results showed that changing the shape of the elastic element can significantly affect the natural frequency and amplitude of the isolator vibration. Studies of the geometric parameters' influence on the dynamic characteristics of cylindrical wire vibration isolators have been carried out in a number of scientific works [13; 34]. For example, in article [34], the authors investigated the influence of such parameters as the number of wires, their diameter, and the distance between the wires, on the natural frequency and gassing of the vibrations of these isolators. Studies have shown that an increase in the number of wires and a decrease in their diameter leads to a decrease in the natural frequency of the cylindrical vibration isolator and an increase in its gassing. The results showed that the diameter and height of the metal springs, which are part of the vibration isolator, have a significant effect on the natural frequency and amplitude of oscillation. [PERSON] investigated the influence of the shape of the elastic element on the dynamic characteristics of the vibration isolator [35]. The results showed that the dynamic stiffness and loss factor calculated by the two different test methodologies were significantly different, indicating that the inertial force effect of the dynamic test equipment should be considered when applying the elliptical method. It was found that the change in the shape of the elastic element can significantly affect the natural frequency and oscillation amplitude of the vibration isolator. [PERSON] studied the optimization of vibration isolator parameters using genetic algorithms [36]. The results showed that optimizing the parameters of the vibration isolator can increase its efficiency. Conducted research in this area has allowed development of new designs for passive vibration-isolating devices with quasi-zero stiffness, in which either specially designed elastic elements are used, or non-standard types of loading of standard elastic elements are implemented [37]. Such designs are not widely used in technology, since most of them are made in the form of passive safety devices with single activation. Their main drawback is the additional setting of the device, which worked during resonant torsional oscillations. In addition, such devices, as a rule, are not designed for reversible drives.