Methods of measuring delay time between periodic sequences of pulses are mostly based on the considered parameter direct measurement. The main disadvantage of this approach is the difficulty of ensuring the measurements accuracy in the noise conditions. The aim of this work was to develop a method that provides the ability to accurately measure small changes in time intervals, based on the analysis of the dynamic properties of the spectrum of the delayed measurement signals sum.The developed method essence is to replace the insensitive registration of changes in the delay time between periodic pulses sequences, registration of changes in the parameters of the characteristic harmonic components of the spectrum of the resulting sum of these signals. In this case, only those harmonic components were taken into consideration that have a maximum sensitivity to delay time deviations and a minimum sensitivity to uncorrelated signal parameters changes.To achieve the maximum effect, the influence of the pulse shape of periodic sequences on the measurement accuracy was investigated. Moreover, the trapezoidal form of impulses was taken as the basic as the most common, into which all other forms of impulses can be reborn (triangular, rectangular, sinusoidal, etc.).The calculation results showed the effectiveness of the proposed method in order to reduce the measurement error of small changes in time intervals. In this case, the attenuation error coefficient compared with the existing measurement method amounted to Kwe = 4,78. Using the proposed approach opens up the possibility of improving the algorithmic support of measuring instruments in order to automate them and increase the measurements accuracy.

The analysis of existing methods of diagnostics test of the windings of asynchronous motors demonstrated that a large error of measurement of diagnostic parameters is due primarily to the instability of the measuring equipment. Sole increasing the sensitivity of the measuring instrument increases the probability of a false conclusion on the faulty winding and can only be used in conjunction with other methods of ensuring high signal-to-noise ratio. During the research fulfillment it was found out that direct way of suppressing uninformative spectral components and distortions caused by the instability of parameters of the testing signal is complex and most difficult to be implemented. Thus, more appropriate is the selection of individual characteristic frequency components of the signal, which has high sensitivity to change of informative parameter of the measuring signal (for example, the time delay between two periodic sequences of pulses) and low sensitivity to random deviations in the signal due to instability in the functioning of the elements of the measuring circuits (for example, to deviation of the phase of the signal). Moreover, adjusting the amplitude, repetition period, pulse duration and delay time pulse sequences it is possible to implement a mathematically justifiable control of the parameters of the spectrum (to move the position of the zeros of the amplitude spectrum, to change the amplitude of the spectral components). The use of the dynamics of the spectra by controlling their parameters will ensure a high sensitivity to change of the informative parameter of the measuring signal, characterizing the degree of development of defects in the windings of asynchronous motors.

The problem of controlling a typical nonlinear servo motor of an unmanned aercraft with non-stationary parameters using a robust PID controller is considered. The procedure for calculating the parameters of a robust PID controller based on the localization method (further - LM PID controller) for continuous and discrete control systems is studied. The influence of disturbing factors (internal and external) acting on the servo motor is considered. It is established that the main perturbations acting on the servo drive include internal perturbations, which are changes in the time constant and its gain from the temperature of the environment and the quality of the supply voltage. The simulation in the class of linear and nonlinear continuous systems showed that a servo drive with a ML PID controller has the property of robustness in the working range of changes in both the input signal and the parameters of the servo drive and controller. Simulation results showing the research are presented. When describing a servo motor with an LM PID controller in the class of linear discrete systems, its robustness is limited by a narrow range of variation of both its parameters and the quantization period of the input signal. As the degree of uncertainty in the parameters of the servo motor increases (approaching the working range of their change), the discrete system loses stability. For the synthesis of robust control circuits of an unmanned aercraft with given characteristics, mathematical dependences of the settling time and static error of a typical servo motor with LM PID controller from the quantization period of the input signal and the degree of uncertainty in its parameters are presented.

The solution of problems of diagnostics of windings of electric machines is associated with the necessity of selection of quasi-periodic test signals against the background noise. In order to highlight useful signals, as a rule, the differences in spectral compositions of signals and noises are used. Ideally, the shape of the optimal filter frequency response should coincide with the shape of the spectrum of the useful signal, which determines the complexity of such a filter. The aim of the research is to increase the accuracy of measurements and simplify the algorithmic support of measuring systems by developing a mathematical tool that makes it possible to uniquely identify and take into account errors caused by the finiteness of the measurement intervals in the processing. Determining a one-to-one relationship between local variations of signal time parameters and alterations in its spectrum parameters is believed to be the reserve of increase of sensitivity of methods of processing of quasi-periodic signals in the conditions of constant growth of computing capabilities of measuring instruments. Variations in the values of the parameters of the signals lead to a violation of the original distribution of the harmonic components, some of the latter being subjected to the greatest alterations changes, and the some other – to the smallest ones. It is proposed to increase the accuracy of measurements due to the replacement the low-sensitivity registration of alterations in the time parameters of signals with the registration of alterations in the parameters of the characteristic harmonic components of the spectrum, which have a maximum sensitivity to deviations of the controlled parameter and a minimum sensitivity to deviations caused by the instability of the measuring equipment. The mathematical tool corresponding to the practice has been developed, that makes it possible to determine unambiguously the errors caused by finiteness of measurement intervals of quasi-periodic signals. Automatic accounting of these errors makes it possible to do without complex correlation processing of quasi-periodic signals that require large computing resources (time and speed of data processing, the amount of RAM) and to ensure the accuracy of measurements.

The principle of organization of strap-down inertial navigation systems is based on numerical integration of angular velocities and accelerations. The purpose of numerical integration algorithms is to approximate the behavior of a dynamic system (unmanned aerial vehicle – UAV) with continuous time using a digital computer. The efficiency of numerical integration is determined by the accuracy and stability of the computational process. The integration algorithm may have a small integration error, but at the same time be inefficient due to the instability of the numerical method when the step or conditions of integration change. The standard way to test integration algorithms for stability is to test them under control operating conditions (when performing a typical UAV flight along the route and canonical movement). The article presents the results of simulation modeling of traditional numerical integration algorithms in the conditions of rectilinear and conical UAV motion, when calculating the values of angular velocities by various methods. The analysis of the obtained research results is carried out, which allows us to choose an algorithm that has an advantage with respect to accuracy and computational simplicity, depending on the flight conditions. For a UAV that has no or minimal undampened angular harmonic oscillations of its body, when performing a typical flight along the route, the best, in terms of accuracy and volume of calculations, is a second-order accuracy algorithm implementing the average speed method. Its average error in calculating angles ranges from 3.6 to 43%, which is approximately equal to the errors values when using the considered algorithms (an algorithm implementing a second approximation to the average speed method, a one-step algorithm of the thirdorder of accuracy), with a three-fold smaller amount of mathematical calculations.