Perturbation analysis and condition numbers of symmetric algebraic Riccati equations

This paper is devoted to the perturbation analysis of symmetric algebraic Riccati equations. Based on our perturbation analysis, the upper bounds for the normwise, mixed and componentwise condition numbers are presented. The results are demonstrated by our preliminary numerical experiments.     

Compensation of unknown sinusoidal disturbances in linear plants of arbitrary relative degree

A new algorithm is proposed for compensating parametrically uncertain harmonic disturbances. In contrast to the known results, the compensation is carried out in the situation where only the output variable and the control signal are measured, and the relative degree of the plant is arbitrary.     

Optimality conditions of sliding modes and the maximum principle for control problems with the scalar argument

Various types of optimality criteria and conditions, which define the set of admissible solution, are brought to the canonical form. For the problem set in this form, the optimality conditions of sliding modes are stated. It is shown that the optimality conditions emerge from these conditions in the form of the maximum principle for problems with a scalar argument and an arbitrary combination of the optimality criterion and constraints.     

On calculation of the power indices with allowance for the agent preferences

In the general case, complexity of the algorithm to calculate the power indices grows exponentially with the number of voting agents. Yet the volume of calculations may be reduced dramatically if many coalitions have equal numbers of votes. The well-known algorithm for calculation of the Banzhaf and Shapley-Shubik indices was generalized, which enables fast calculation of the power indices where entry of the voting agent into a coalition depends on its preferences over the set of the rest of agents.     

Design of modified PD algorithm to control angular motion of large space structure

Consideration was given to the design of an algorithm to control orientation of the large space structure (LSS) in the presence of infralow (less than 0.01Hz) frequencies of elastic oscillations exerting considerable influence on the quality of transients due to closeness of the LSS eigenfrequencies to the frequency of control of the object’s “rigid” motion. Procedure for designing a modified PD-algorithm for orientation of the LSS with infralow frequencies of elastic structural oscillations was described. Methods were proposed for calculation of the coefficients of additional components of the modified algorithm and determination of the LSS eigenfrequency boundary to the right of which the orientation control system is robust to the deviations of the object frequencies or inaccuracy of their definition. Some examples of mathematical modeling of the processes of the relay gyroforce control of LSS orientation using the proposed algorithm were given.     

Robust control of composite beams

The structure uncertainty effect is considered on actively controllable composite beam that is a part of the structure of a civil building in a seismodangerous zone. The solution of the problem for active control of vibrations of the composite beam is based on the introduction of a simplified model of sensors and an actuator, which are implemented in the form of piezoelectric plates pasted on two opposite planes of the beam. A suggestion is made of the practical approach that affords the robust control of the composite beam and is founded on the modern H ₂- and H _∞-methods of the theory of control. The effectiveness of the suggested approach for the suppression of vibrations of the composite beam under consideration is illustrated by the examples of numerical modeling.     

Problem of reconstructing input signals under communication constraints

For a linear controllable system, the problem of reconstruction of all input signals, which are compatible with the measured signal, is considered. It is assumed that information can be transmitted in a processing center only via digital communication channel at discrete time instants, and the word length is limited. In this connection, there are encoding and decoding devices in the communication channel. For simplicity, the communication channel is assumed to be noiseless and delay-free. Defining relationships are obtained for the set of compatible input signals, as well as relationships between reconstruction precision, length of transmitted word and transmission frequency.     

A tracking problem for mechanical systems with delay in control

A problem of tracking for mechanical systems described by nonstationary nonlinear equations is studied at relay control with delay is studied. An approach that makes it possible to solve problems of tracking for mechanical systems whose parameters may continuously vary with time is developed. This approach is based on the transformation of the system and construction of a Lyapunov vector-function with components of the form of vector norm.     

The order of singularity of pulse optimal controls in degenerate linear-quadratic optimization problems with time delay

In the paper, we study a problem of minimization of degenerate integral quadratic functional of special delayed structure (a subintegral function contains items concentrated at the moment and items with delay in phase coordinates) on trajectories of a linear system of differential equations with time delay in phase coordinates considered on a finite period of time. Sufficient conditions for the existence of optimal program control in space of generalized functions of the lth order of singularity are established and an optimal control is obtained. A special feature of the problem is that the optimal program contains pulse components concentrated at the ends of the control gap.     

Analysis of probability distribution of a random variable of an execution time of the program in the presence of random failures

The mathematical model of an estimation of an execution time of the program in the presence of random failures is studied. For decreasing of influence of failures on a program execution time the known method of checkpoints is considered. The main objective consists in reception of the formula for a distribution function of a random variable of an execution time of the program and an estimation of a quantile of the received distribution. Properties of a mean value of a random variable of an execution time of the program are studied.