Volume 5 Issue 1
Authors: De-zhi Tang; Xiao-yong Guo; Hong Jiang; Jian-hong Wang; Yong-hong Zhu
Abstract: Virtual reference feedback tuning control is a data-driven control strategy, where there is no model identification process. To compute the asymptotic covariance matrix corresponding to the unknown parameter, firstly the error using Taylor series expression is expanded. The two diagonal sub-matrices in the asymptotic covariance matrix are denoted as the asymptotic covariance matrix expression of the two unknown parameter estimation vectors in the closed-loop system. Based on this asymptotic covariance matrix, an optimal filter is constructed by solving one optimization problem on the trace operation. Finally, the efficiency and possibility of the proposed strategy are confirmed by the simulation example results.
Keywords: Virtual Reference Feedback Tuning Control; Asymptotic Analysis; Stochastic Optimization
Authors: Chungang Zhao; Lina Zhang; Jinlong Xu; Aihua Zhang
Abstract: To deal with the tracking control problem for dynamic positioning (DP) marine crafts with strong nonlinear and uncertainties, the Integral Constant Bearing (ICB) guidance algorithm is proposed by introducing the integral term to the Constant Bearing (CB) guidance algorithm. By combining the integral sliding mode control algorithm with the ICB guidance algorithm, the ICB guided tracking control scheme is proposed based on the strong nonlinear mathematic model. Both of the theoretical analysis and the numerical simulation are carried out to verify the good control performance the control approach.
Keywords: DP Marine Crafts; ICB Guidance Algorithm; Integral Sliding Mode; Stability
Authors: S. Saravanan; D. Krishna Sundar; K. Jeganathan; V.S.S. Yadavalli
Abstract: In this paper, a perishable inventory system model with multiple working vacations and orbital search simultaneously is considered. The customer arrivals to the service centre assumed to be a Poisson process. Whenever the waiting place is full, arrivals of new customers enter into the orbit. The server searches for an orbiting customer with a certain probability once the waiting place becomes empty and inventory will be positive. In the case of search time, the study assumes it to be negligible. The steady-state case assumes that joint probability distribution of the random variables in the inventory model. The measures of system performance in the steady state are obtained, and the total average cost is also computed. Numerical evidences are provided to support the proposed model.
Keywords: Working Vacation; Delay Period; Markov Process; Orbital Search
Authors: De-zhi Tang; Jian-hong Wang
Abstract: In these years, direct data driven control is widely studied to replace the classical model based control. The main advantage of direct data driven control is that the identification process of the plant does not need. Then the controller can be designed based on input-output measured data directly. In this work, the problem on how to design optimal input signal for direct data driven control is studied and one optimal correlation function of the input signal is also proposed here. The excitation signal is designed such that the expected value of the considered control is reduced. Here some results and conditions used to improve the convergence of classical prediction error method into direct data driven control are extended. Furthermore, a candidate domain of attraction for the objective function is introduced and one convergence condition which ensures that a given set is a candidate domain of attraction is derived. Generally, all results and conditions corresponding to the optimal input signal for direct data driven control are different from the classical methods. Finally, the efficiency and possibility of the proposed strategy are confirmed by the simulation example results.
Keywords: Direct Data Driven Control; Optimal Input Signal; Asymptotic Variance; Convergence Condition
Authors: Maryam Shojaei Baghini; Virendra Sule; Mayuresh Bakshi
Abstract: A theory of stable interconnection of multiport active networks is developed using the stable coprime fractional representation of hybrid network functions at their ports. One of the difficulties in designing stable port interconnection of networks has been that the feedback signal flow graph of the interconnection cannot be easily obtained apart from simplest single port networks. This paper resolves this problem by directly developing the theory in terms of network function of port interconnection. The resulting mathematical problem turns out to have close analogy with stabilization problem of multi input multi output (MIMO) feedback system theory with the major difference that the signal flow graph of a feedback system is never used and that the definition of stability is also not formulated as two input two output map stability as in feedback theory. Hence this problem turns out to be a new application of the coprime fractional approach well known in feedback control. Despite these differences, the conditions for stability turn out to have a close mathematical analogy with the Bezout identity in terms of fractional parts of hybrid network functions analogous to that in feedback theory. A complete parameterization of stabilizing multiport network functions for a given analog multiport network and that of the interconnection is derived. This theory proves that interconnection of physical systems such as networks need not be designed by transforming to feedback signal flow graph and can be handled directly in terms of network interconnections. In particular the stability condition gives a Nyquist stability analog for stability of multiport interconnection without computing an open loop transfer function. The parameterization of the interconnection also facilitates an affine optimization problem for design of such interconnection. Much of the classical theory of synthesis of circuits and their connections is valid only for passive circuits which are always stable. On the other hand active networks can be unstable and can lead to unstable interconnection even if the component parts are stable. Hence this stabilization theory is essential for design of active network interconnections.
Keywords: Coprime Factorization; Feedback Stabilization; Multiport Network Connections