Vol 56, No 2 (2017)

The algorithms for stabilizing particular systems of differential equations with a constant delay are proposed; here, the right side of one of subsystems contains the multiplier e^t. The sufficient conditions of the instability and the stability in a first approximation are obtained.

The problem of time quasi-optimal deceleration of the rotations of a dynamically symmetric rigid body is studied. It is assumed that the body contains a point mass connected to it with a strong viscoelastic element (damper). The body is acted on by a small linear resistance torque of the medium that is proportional to the angular momentum and a small control torque bounded by an ellipsoidal domain. An approximate synthesis of control is proposed, and an asymptotic solution based on a procedure of averaging the precession motion over the phase is obtained; numerical integration is performed. The main properties of the quasi-optimal motion are determined.

We propose a constructive algorithm for determining the guaranteed accuracy of estimating the state vector of an unperturbed linear dynamic system for an arbitrarily taken algorithm in the context of a problem with measuring errors that are limited in magnitude [1]. We also present the results of determining the measure of the guaranteed accuracy of estimation for the class of algorithms that minimize the Hölder norm.

The proposed algorithms basically follow a greedy strategy, and a limited search procedure is invoked only at the steps at which the greedy choice cannot lead to the optimal solution. The principle of these algorithms design are illustrated using the problem of finding the maximum number of compatible jobs as an example. The results of applying the proposed algorithms for scheduling computations in distributed systems are described.

The problem of making a feasible schedule in a preemptive multiprocessing system with identical processors and several types of additional recourses is considered in the case when the task execution intervals are given and the durations of task execution linearly depend on the amount of the additional resource allocated to them. Algorithms based on reducing this problem to a network flow problem and a system of linear constraints are developed.

Recommender systems and services are now widely used to support decision-making in the fields characterized by the selection from a large number of alternatives with a significant influence of subjective preferences. A comprehensive multimodel approach to the development of context-aware recommender systems in the field of tourism information support is proposed. In particular, it is proposed to construct a recommender system based on loosely coupled modules, in which both personalized and nonpersonalized recommendation methods are implemented, and the synthesis module, which adapts the module system to the specific conditions of different kinds of initial information.

Theoretical bases for controlling the application of coatings to the inner surface of pipes and other hollow products are considered based on the stabilization of the velocity of the coating material in the product cavity taking into account temperature and viscosity. The device makes it possible to automatically compensate for the variation in the coating thickness depending on temperature taking into account the characteristics of the used control equipment. The dependence of the coating thickness on temperature and material velocity is described. The system that implements the proposed method in the MATLAB + SIMULINK shell is simulated. The optimal values of the system gain and level sensor sensitivity that minimize the dynamic error of the control system are determined.

Methods for designing trajectories of spacecraft (SC) for missions that need to increase the inclination of their orbits to the ecliptic using energy-efficient gravity assist maneuvers (GAMs) around planets, their moons, and small Solar system bodies are developed. The focus is on the development of algorithms (taking into account accurate ephemerides) for designing chains of multiple GAMs that significantly raise the orbit of a SC above the plane of the ecliptic. Complete analytical formulas for the change of inclination as a result of a GAM in the general case of elliptic orbits of the SC and the partner planet are obtained.

Methods for dynamic parameters identification and vibrations estimation of large spacecraft with flexible structures are reviewed. Different approaches to the structural deviation determination and to the vibration frequency identification by processing measurements from the onboard sensors are compared. Measuring devices and sensors for the motion estimation of large nonrigid structures are reviewed.

This paper is devoted to improving the automatic safe motion control system of a robotic manipulator, in such a way that the system, in addition to its primary function of shutting down the power drives in the case of overload, becomes capable of checking the operability of all its components. The proposed modification of the control system’s architecture makes it possible to prevent large deviations from the programmed motion even if only some of the console controllers remain operational.