Decentralized state-feedback stabilization and robust control of uncertain large-scale systems with integrally constrained interconnections

This paper is concerned with a problem of stabilization and robust control design for interconnected uncertain systems. A new class of uncertain large-scale systems is considered in which interconnections between subsystems as well as uncertainties in each subsystem are described by integral quadratic constraints. The problem is to design a set of local (decentralized) controllers which stabilize the overall system and guarantee robust disturbance attenuation in the presence of the uncertainty in interconnections between subsystems as well as in each subsystem. The paper presents necessary and sufficient conditions for the existence of such a controller. The proposed design is based on recent absolute stabilization and minimax optimal control results and employs solutions of a set of game-type Riccati algebraic equations arising in H_∞ control.     

Optimal computer control via communication channels with irregular transmission times

We study a linear discrete-time partially observed system perturbed by white noises. The observations are transmitted to the controller via communication channels with random transmission times. Various measurement signals may incur independent delays, be lost or corrupted. Under certain assumptions, a recursive minimum variance state estimator is proposed. A finite horizon linear-quadratic optimal control problem is solved. We also find a solution for the problem of minimizing the average cost per unit time over the infinite planning horizon.     

Nonlinear control for reactive navigation of a nonholonomic robot for environmental nongradient‐based extremum seeking in maze‐like scenes

A single Dubins car‐like mobile robot travels with a constant speed in a planar workspace cluttered with arbitrarily complex obstacles, possibly maze‐like ones. An unknown scalar field is defined on the plane. The sensors supply the robot with the field value at its current location and its distance to the nearest obstacle. We present a new control law that drives the robot to the location where the field attains its maximum, while avoiding collisions with the obstacles. This is justified by a mathematically rigorous global convergence result and is confirmed via computer simulations. The proposed algorithm does not use gradient estimation and is nondemanding with respect to computation and motion. Copyright © 2017 John Wiley & Sons, Ltd.     

Upgrade of refractory lining of teeming ladles

A gradual upgrade of refractory lining of 160-ton teeming ladles, the disadvantages of the previous lining schemes, and methods for their elimination are described. The implementation of developed techniques has increased the resistance of teeming ladle lining by 60% (from 50 to 80 heats) and the consumption of refractory in the working layer of lining has decreased by 35.7% (from 4.79 to 3.08 kg/t of steel. __________ Translated from Novye Ogneupory, No. 7, pp. 18–19, July, 2007.     

Hybrid dynamical systems: robust control synthesis problems

The paper presents a new approach to robust control synthesis problems for hybrid dynamical systems. The hybrid system under consideration is a composite of a continuous plant and a discrete event controller. State and output feedback problems are considered. The main results are given in terms of the existence of suitable solutions to a dynamic programming equation and a Riccati differential equation of the H^∞ filtering type. These results show a connection between the theories of hybrid dynamical systems and robust and nonlinear control.     

An investigation of molecular mobility in polymers under rubbing contact

The results of investigations into the molecular mobility of polymer materials are reported. Under frictional interaction, certain structural variations take place in the surface layers and influence the molecular mobility; the effect of loading, the speed of the relative sliding and the material of the counterface are discussed.     

Peculiarities of formation and properties of metal-polymer sliding electrical contact

The properties of collector films formed on copper slip rings during rubbing by various types of brush have been investigated. Structural peculiarities are discussed and a model is suggested for the structure of collector films formed during the operation of metal-polymer brushes.