ABSOLUTE STABILIZATION RELATED TO CIRCLE CRITERION: AN LMI-BASED APPROACH

A method is proposed for synthesizing output feedback controllers for nonlinear Lur' e systems . The problem of designing an output dynamic controller for uncertain-free systems and systems subject to multiplicative norm-bounded perturbations in the linear part were proposed respectively. The procedure is based on the use of the absolute stability, through the circle criterion, and a linear matrix inequalities (LAI) formulation. The controller existence conditions are given in terms of existence of suitable solutions to a set of parameter-dependent LMIs.

LMI approach for absolute stability of general neutral type Lurie indirect control systems

This paper deals with the problem of the absolute stability for general neutral type Lurie indirect control systems by Lyapunov method and linear matrix inequality （LMI） technique. Delay-dependent sufficient conditions for the absolute stability are derived and expressed as the feasibility problem of LMI, which can be easily solved by Matlab Toolbox. Finally, some examples are provide to demonstrate the effectiveness of proposed method.

Analysis of Absolute Stability for Time-delay Teleoperation Systems

In this paper, a new bilateral control algorithm based on absolute stability theory is put forward, which aims at the time-delay teleoperation system with force feedback from the slave directly. In the new control algorithm, the delay-dependent stability, instead of delay-independent stability, is taken as the aim of control design. It improves the transparency of the system at the price of unnecessary stability. With this algorithm, the time-delay teleoperation systems have good transparency and stability. A simulation system is established to verify the effect of this algorithm.

Absolute Stability of Nonlinear Systems with Two Additive Time-varying Delay Components

In this paper, we present a new sufficient condition for absolute stability of Lure system with two additive time-varying delay components. This criterion is expressed as a set of linear matrix inequalities （LMIs）, which can be readily tested by using standard numerical software. We use this new criterion to stabilize a class of nonlinear time-delay systems. Some numerical examples are given to illustrate the applicability of the results using standard numerical software.

ABSOLUTE STABILITY OF CONTROL SYSTEM WITH MULTI-NONLINEAR FEEDBACK TERMS

In this paper, the absolute stability of control systems with multi nonlinear feedback terms are studied. The sufficient and necessary conditions of absolute stability are obtained. Some applied sufficient conditions of absolute stability are given.

ABSOLUTE STABILITY OF TIME-VARYING NONLINEAR CONTROL SYSTEM

In this paper the authors study two classes of time-varying nonlinear control systems. A few sufficient conditions of absolute stability of these systems were obtained by means of classical analysis and the analogue of the variation of constants formula of nonlinear systems. Moreover, they gave some sufficient conditions of absolute stability in Hurwitz angle for these systems.

Absolute stability of the solidification interface in a laser resolidified Zn-2wt.%Cu hypoperitectic alloy

This paper reports on laser surface remelting experiments performed on a Zn-2wt.%Cu hypoperitectic alloy by employing a 5kW CW CO2 laser at scanning velocities between 6 and 1207mm/s. The growth velocities of the mi- crostructures in the laser molten pool were accurately measured. The planar interface structure caused by the high velocity absolute stability was achieved at a growth velocity of 210 mm/s. An implicit expression of the critical solidification velocity for the cellular-planar transition was carried out by nonlinear stability analyses of the planar interface. The results showed a better agreement with the measured critical velocity than that predicted by M-S theory. Cell-free structures were observed throughout the whole molten pool at a scanning velocity of 652 mm/s and the calculated minimum temperature gradient in this molten pool was very close to the critical temperature gradient for high gradient absolute stability （HGAS） of the η phase. This indicates that HGAS was successfully achieved in the present experiments.

ABSOLUTE STABILITY OF GENERAL LURIE CONTROL SYSTEMS

In this paper, we investigate the absolute stability of the general Lurie control systems. The necessary and sufficient conditions for absolute stability are obtained. These conditions can be readily checked and are convenient in application.

NASCS FOR THE ABSOLUTE STABILITY OF LURE DIRECT CONTROL SYSTEMS

In this paper, we transform n-th order Lure direct control systems into nonlinear systems with separating variables, and induce a concept for absolute stability of part arguments. The necessary and sufficient conditions (NASC) for the absolute stability of Lure direct control systems are given and some sufficient conditions are obtained

Real-time digital image stabilization based on regional field image gray projection

Digital image stabilization technique plays important roles in video surveillance and object acquisition.Many useful electronic image stabilization algorithms have been studied.A real-time algorithm is proposed based on field image gray projection which enables the regional odd and even field image to be projected into x and y directions and thus to get the regional gray projection curves in x and y directions,respectively.For the odd field image channel,motion parameters can be estimated via iterative minimum absolute difference based on two successive field image regional gray projection curves.Then motion compensations can be obtained after using the Kalman filter method.Finally,the odd field image is adjusted according to the compensations.In the mean time,motion compensation is applied to the even field image channel with the odd field image gray projection curves of the current frame.By minimizing absolute difference between odd and even field image gray projection curves of the current frame,the inter-field motion parameters can be estimated.Therefore,the even field image can be adjusted by combining the inter-field motion parameters and the odd field compensations.Finally,the stabilized image sequence can be obtained by synthesizing the adjusted odd and even field images.Experimental results show that the proposed algorithm can run in real-time and have a good stabilization performance.In addition,image blurring can be improved.

ON THE ABSOLUTE STABILITY OF A CLASS OF INDIRECT CONTROL SYSTEMS

The absolute stability of a class of indirect control systems was studied by applying the theory of Hermitian quadratic form and Jordan normal form. The algebraic formal criteria for the absolute stability are established, and these results are new and useful.

On absolute stability of Lur'e control systems with multiple non-linearities using linear matrix inequalities

Necessary and suffcient conditions for the existence of a Lyapunov function in the Lur ’ e form to guarantee the absolute stability of Lur’ e control systems with multiple non-linearities are discussed in this paper. It simplifies the existence problem to one of solving a set of linear matrix inequalities (LMIs). If those LMIs are feasible, free parameters in the Lyapunov function, such as the positive definite matrix and the coefficients of the integral terms, are given by the solution of the LMIs. Otherwise, this Lyapunov function does not exist. Some sufficient conditions are also obtained for the robust absolute stability of uncertain systems. A numerical example is provided to demonstrate the effectiveness of the proposed method.

NECESSARY AND SUFFICIENT CONDITIONS FOR THE ABSOLUTE STABILITY OF DISCRETE TYPE LURIE CONTROL SYSTEM

In this paper. it is discussed that the absohue stability for zero solution of thediscrete type Lurie control systmin which the nonlinear function f(σ) satisfying conditions as followsIt gives the necessary and sufficent conditions for the absolute stability forystem (I) under conditions (2).We also obtain the sufficient criteria for absolutesiability of the simplified system of (I) under conditions (3) .

The Sufficient Conditions for Robust Absolute Stability of Lurie Control Systems

In this paper, the problem of absolute stability of continuous time with parametric nonlinear system uncertainty of a linear part and sector uncertainty of its nonlinear part is considered, the and sufficient conditions for absolute stability of direct and indirect control systems are presented. The corresponding results for robust absolute stability are improved.

The Absolute Stability of Several Classes of Nonlinear Control Systems

Absolute stability problem has theoretical and engineering importance for control engineering and control theory. In this paper, based on the dimension reducing method, sufficient conditions for the absolute stability of several classes of Lurie control systems are given.

NECESSARY AND SUFFICIENT CONDITIONS FOR THE ABSOLUTE STABILITY OF DISCRETE TYPE LURIE CONTROL SYSTEM

In this paper. it is discussed that the absolute for zero solution of the discrete type Lurie control systemin which the nonlinear function f(σ)satisfying conditions followsIt gives the necessary and sufficient conditions for the absolute stability for system (1) under conditions (2).We also obtain the sufficient for absolute stability of the simplified system of (1) under conditions (3) .

THE CRITERIONS FOR ABSOLUTE STABILITY OF DIRECT CONTROL SYSTEMS OF LURIE TYPE

In this paper, we give necessary and sufficient conditions for absolute stability of several classes of direct control systems, and discuss the absolute stability of the first canonical form of control system. The corresponding results in references [3,5,6] and [7] are improved.

Stability and guaranteed cost control for uncertain time-delay Lur'e systems

The problem of delay-dependent stability and guaranteed cost control （GCC） for a class of uncertain time-delay Lur＇e systems are studied. By using an improved integral inequality,a less conservative delay-dependent stability criterion is formulated as the feasibility problem of the linear matrix inequality （LMI）. The criterion is proved theoretically to be less conservative than some existing results for linear time-delay systems. Because of the fact that the matrices in the LMI-based stability criteria usually have different dimensions, different structures, and different variables, the conservatism analysis of the criteria is difficult. This study brings about a new insight into the comparison of conservatism among different stability criteria, which are expressed in certain LMI forms. The existence of the guaranteed cost controller is given in terms of matrix inequalities. The condition can be solved by using an iterative procedure and does not need any parameter tuning. A numerical example is given to illustrate the effectiveness of the proposed method.

Block Extension of a Single-Step Hybrid Multistep Method for Directly Solving Fourth-Order Initial Value Problems

This article aims to derive, analyse, and implement an efficient one-step implicit hybrid method with block extension comprised of seven off-step points to directly solve Initial Value Problems (IVPs) of general four-order ordinary differential equations. For the resolution of the fourth-order IVPs, the exact was approximated by a polynomial termed basis function. The partial sum of the basis function and its fourth derivative were interpolated and collocated at some selected grid and off-grid points for the unknown parameters to be determined. The derived method, when tested, is found to be consistent, convergent, and zero-stable. The method’s accuracy and usability were experimented with using specific sample problems, and the findings revealed that it surpassed some cited methods in terms of accuracy.

Absolute Stability of General Lurie Control Systems with Multi-Nonlinear Feedback Terms

In this paper, the problenl of absohlte stability for general Lurie control systems with multi- nonlinear feedback terms is investigated. From the Lyapunov function approach. new necessary and sufficient conditious and some practical sufficient conditions of absolute stability are derived. which improve the absolute stability for the set. A numerical examplc illustrates the effectiveness of the proposed results.