Hybrid journal (It can contain Open Access articles) ISSN (Print) 0265-0754 - ISSN (Online) 1471-6887 Published by Oxford University Press[368 journals]

Authors:Sivaranjani KK; Rakkiyappan RR, Lakshmanan SS, et al. Abstract: This paper deals with the problem of robust exponential stabilization of offshore steel jacket platforms, where linear fractional uncertainties and randomly occurring uncertainties are taken into account. In this work, we introduce a sampled-data controller with $m$ stochastically varying sampling intervals whose occurrence probabilities are given constants and satisfy Bernoulli distribution. A discontinuous type Lyapunov–Krasovskii functional with triple integral terms based on the extended writinger's inequality is constructed and some sufficient conditions that guarantee the exponential stabilization of considered system are derived in terms of linear matrix inequalities by using Jensen's inequality and reciprocally convex technique. Finally, a numerical example is presented to show the effectiveness of the proposed results. PubDate: 2015-09-11

Authors:Sun Z; Xia Y, Na X. Abstract: In this paper, dynamic role assignment and collision avoidance based on consensus tracking algorithm for multi-agent systems are investigated. First, based on the traditional consensus protocol, dynamic role assignment is introduced to minimize the total cost of the team of agents by solving an optimal problem using Hungarian algorithm. Secondly, considering the existence of local minimum position of traditional potential field function for collision avoidance, modified potential field function is proposed to guarantee the agent avoiding the obstacle. Finally, modified consensus algorithms containing corresponding gradient terms are presented for multi-agents systems. Simulations and experiments are included to show the effectiveness of the proposed algorithms. PubDate: 2015-09-09

Authors:Jasso-Fuentes H; López-Barrientos J, Escobedo-Trujillo B. Abstract: This paper deals with infinite-horizon non-zero-sum stochastic differential games with discounted and average payoffs and an additive structure. Our main objective is to give conditions for the existence of Nash equilibria in the set of stationary randomized strategies for the discounted payoff and then, by following the vanishing discount approach, to show the existence of Nash equilibria for the average payoff. To this end, we use standard dynamic programming techniques. PubDate: 2015-08-31

Authors:Tehrani HA; Esmaeili JJ. Abstract: In this article, necessary and sufficient stability conditions of fractional-order periodic discrete-time linear systems will be established. A new notion of the practical stability of these systems is introduced. Stabilization of unstable systems by pole assignment of monodromy matrix using a special form of state feedback matrices is done to modify the dynamic response of the system. Numerical examples illustrate the effectiveness of the proposed approaches. PubDate: 2015-08-27

Authors:Dadkhah M; Farahi M, Heydari A. Abstract: Optimal control problems for a class of time-delay non-linear systems with quadratic performance index are studied. The properties of the hybrid functions which consist of block-pulse functions and orthonormal Taylor series are presented. By expanding various time functions in the systems as their truncated hybrid functions, we attain to algebraic equations and by means of operational matrices of integration, delay and product we reduce the solution of optimal control problem to the solution of algebraic equations. Illustrative examples are included to demonstrate the validity and applicability of the technique. PubDate: 2015-08-17

Authors:Sakthivel RR; Santra S, Mathiyalagan KK, et al. Abstract: This paper focuses on the dissipative reliable sampled-data control for a class of linear uncertain systems against actuator failures. The main purpose is to design a state feedback reliable dissipative control law such that the resulting closed-loop uncertain system is strictly $({\mathcal Q}, {\mathcal R}, {\mathcal S})-\theta $ dissipative for all admissible actuator failures with a certain prescribed performance constraint. By constructing a proper Lyapunov–Krasovskii functional based on sampled-data strategy, a set of sufficient condition for the existence of the controller is derived in terms of the linear matrix inequality (LMI) technique. It has also been shown that the solutions to the dissipative reliable sampled-data control can be obtained by solving the proposed LMIs. The main advantage of this paper is it unifies $H_\infty $ and passivity control and provides a more flexible control design as it allows for a better trade-off between phase and gain performances. Finally, a numerical example based on vehicle dynamics model is provided to demonstrate the effectiveness of the proposed design technique. PubDate: 2015-08-06

Authors:Lu L; Wang J, Zhao D. Abstract: This paper addresses a dynamic feedback stabilization of an interconnected pendulum system with a memory type heat equation, where the kernel memory is an exponential polynomial. By introducing some new variables, the time-variant system is transformed into a time-invariant one. The detailed spectral analysis is presented. Remarkably, the resolvent of the closed-loop system operator is not compact anymore. The residual spectrum is shown to be empty and the continuous spectrum consists of finite isolated points. Furthermore, it is shown that there is a sequence of generalized eigenfunctions, which forms a Riesz basis for the Hilbert state space. This deduces the spectrum-determined growth condition for the $C_0$-semigroup, and the exponential stability is then followed. Finally, some numerical simulations are presented to show the effectiveness of this feedback control design. PubDate: 2015-07-28

Authors:Teymurov R. Abstract: We study a problem of optimal scanning control for systems obeying a heat equation together with systems of ordinary differential equations. Sufficient conditions for Frechet differentiability of the performance criterion and an expression for its gradient were determined. The necessary optimality conditions were established in the form of the pointwise and integral principles of maximum. PubDate: 2015-07-22

Authors:Lestas M; Ioannou P, Pitsillides A, et al. Abstract: A number of congestion control schemes which adopt the max–min fairness criterion and do not require maintenance of per flow states within the network have been proposed in the literature. The establishment of global asymptotic stability remains an open challenging research topic. In this paper, we show global asymptotic stability of two decentralized max–min congestion controllers in the absence and presence of queueing dynamics when the propagation delays are assumed to be zero. In particular, we show that these max–min congestion control schemes applied to a network of arbitrary topology, guarantee that the user sending rates converge asymptotically to the max–min allocation values for any arbitrary feasible initial condition. The second algorithm which accounts for queueing dynamics, typical in store and forward networks, does not only guarantee convergence of the sending rates to their max–min allocation values but also guarantees that the queue sizes within the network all converge to zero when there is only one bottleneck link at each path. PubDate: 2015-07-21

Authors:Meslem N; Ramdani N. Abstract: A set-membership (SM) approach is proposed to design reliable static stabilizing controllers for non-linear dynamical systems. First, the control design problem is reformulated as a parameter identification issue in an unknown-but-bounded error framework. Then, a new dual set integration method for reachability computation is introduced. Finally, the latter dual method is used in conjunction with set inversion techniques via interval analysis, in order to develop an SM parameter estimation algorithm to solve the control design problem. The identified feedback control must achieve two aims. The first aim is that, starting from a given bounded set of initial states, the state trajectories generated by the controlled non-linear system have to reach in a finite-time a desired target set. The second aim is to ensure asymptotic stability of the controlled system over the target set. The effectiveness of the proposed method is illustrated through a complex non-linear system. PubDate: 2015-07-17

Authors:Otsuka NN; Saito HH, Conte GG, et al. Abstract: In this paper, we will first study two robust controlled invariant subspaces under common input for a family of vertex systems and for a family of subsystems. Next, disturbance decoupling problems under arbitrary switching via state feedback for polytopic uncertain switched linear systems are formulated, and necessary and sufficient conditions for the problems to be solvable are presented. Further, the disturbance decoupling problems with exponential stability under arbitrary switching are also formulated, and solvability conditions for the problems are briefly discussed. Finally, a numerical example is also investigated. PubDate: 2015-07-14

Authors:Ben Hamed A; Ben Hamed B. Abstract: In this paper, a Hopfield network model with three neurons, bidirectional connection and multiple delays is considered. We aim to show that the connection topology is very important. In fact, we consider the connected weights of this system as bifurcation parameters, and the critical values where a Bogdanov–Takens bifurcation occurs are derived. Using the normal form method and the centre manifold theory, we obtain the normal form of our system and study its dynamical behaviours. Finally, a numerical example is given to demonstrate the validity of the results. PubDate: 2015-07-13

Authors:Zhao M; Liu R, Gao Y. Abstract: This paper is concerned with the problem of dissipative lag synchronization (LS) for two identical Lur'e systems with unknown external disturbances. The disturbances are supposed to be generated by the exogenous systems with and without time-delay. Based on the disturbance-observer-based control method, the linear matrix inequality technique and the dissipativity theory, the disturbance observers are developed to ensure the boundedness of the disturbance error dynamics and the dissipativity of the resultant LS error system. By using the sliding-mode control (SMC) approach, an integral-type sliding surface function is constructed and a dissipative SMC law is established to render the disturbance rejection and realize LS between the master and slave systems, and an integral sliding-mode controller is designed to guarantee the reachability of the specified sliding surface. Finally, the Chua's circuit is used as a numerical example to illustrate the effectiveness of the proposed method. PubDate: 2015-07-13

Authors:Liu X Xu G. Abstract: In this paper, we consider the exponential stabilization for Timoshenko beam with different delays in the boundary control. Suppose that the controller outputs are of the form $\alpha _{1}u_{1}(t)+\beta _1u_1(t-\tau _{1})+\gamma _{1}u_1 (t-\tau _{2})$ and $\alpha _{2}u_{2}(t)+\beta _2u_2(t-\tau _{1})+\gamma _{2}u_2(t-\tau _{2}),$ where $u_1(t)$ and $u_2(t)$ are the inputs of boundary controllers. PubDate: 2015-07-08

Authors:Liu W; Xu S, Zhang B, et al. Abstract: In this paper, we consider the global stabilization problem of high-order feedforward systems with unknown control directions. By combining the Nussbaum-type gain method and adding a power integrator technique, a robust adaptive state feedback controller is proposed. The designed controller is not only to ensure the global boundedness of all signals of the closed-loop system, but also to guarantee that the system state asymptotically converges to zero. A simulation example is included to illustrate the effectiveness of the design approach. PubDate: 2015-06-26

Authors:Dehghan R; Keyanpour M. Abstract: In this paper, we present a method based upon the moments problem for solving a class of fractional optimal control problems (FOCPs) with time delay. The performance index of the FOCP is considered as a function of both the state and control variables and the dynamics of system is given as an ordinary fractional differential equation with time delay. The fractional derivative (FD) is described in the Riemann–Liouville sense in which the FD order is $\alpha \in (0,1]$. The main reason of using this technique is the convexification of a non-linear and non-convex FOCP with time delay in which the non-linearities in the control variable can be expressed as polynomials. The Grünwald–Letnikov formula is used as an approximation for FD in numerical computations. Some numerical examples are given to illustrate the effectiveness of our method. PubDate: 2015-06-26

Authors:Tsachouridis VA. Abstract: This paper presents an algorithm based on a complex line homotopy mapping for the numerical solution of systems of coupled algebraic matrix Riccati equations which often met in continuous time control system design problems. Well-defined complex homotopy paths lead to solutions globally from independent initial conditions, and they are computed via continuous dynamic flow algorithms (ordinary differential equation solvers). Although the homotopy mapping is complex it is shown how it is possible in practice to obtain desired real solutions of certain definiteness even from zero initial conditions. Moreover, a scaling method is deployed within the algorithms for numerical enhancement and its effect to homotopy paths, convergence and stability is experimentally studied. In addition, a first-order perturbation analysis framework for the assessment of computed solutions is provided. Comparisons with other existing methods from the literature are made through several numerical examples considering mixed H$_{2}$/H$_{\infty }$, Nash games and stochastic control system design problems, where the efficiency of the proposed algorithm is illustrated. It is worth noticing that algorithmic implementation and numerical experimentation with complex homotopies for the coupled algebraic Riccati equations under study appears to be absent the literature. Hence, the contribution of the present paper to related problems in systems and control. PubDate: 2015-06-25

Authors:Alexandrov VV; Bugrov DI, Morales G, et al. Abstract: An application of the V. Boltyanski's tent method for solving minmax stabilization problem is described. Necessary conditions for functional minimum in a stability region with given stability factor are formulated as a theorem. The minmax strategy algorithm formed on the base of this theorem is proposed for the solution of maxmin testing problems. A workability of the theorem formulation is demonstrated at three examples. PubDate: 2015-06-24

Authors:Miao X Li L. Abstract: This paper focuses on observer design for a class of Lipschitz discrete-time systems. A generalized Lipschitz condition is firstly introduced to the observer design for a class of non-linear discrete-time systems. The proposed design method of state observer extends the existing results due to the generalized Lipschitz condition can make better use of the structural knowledge of the non-linear part. Both full- and reduced-order observer designs for non-linear discrete-time systems are investigated. New observer synthesis conditions are derived by using a linear matrix inequality-based technique and theory of the quadratic stability. Numerical examples are given to illustrate the validity and advantages of the proposed theoretical results. PubDate: 2015-06-23