Adaptive robust sampled-data control of a class of systems under structured perturbations

Robust adaptive sampled-data control of a class of linear systems under structured perturbations is considered. The controller is a time-varying state-feedback law having a fixed structure, containing an adjustable parameter, and operating on sampled values. The sampling period and the controller parameter are adjusted with simple adaption rules. The resulting closed-loop system is shown to be stable for a class of unknown perturbations. The same result is also shown to be applicable to decentralized control of interconnected systems

Robust sampled-data control

Ankara : Department of Electrical Engineering and Institute of Graduate Studies, Bilkent Univ., 1995.Thesis (Ph.D.) -- Bilkent University, 1995.Includes bibliographical references leaves 73-75.Robust control of uncertain plants is a major area of interest in control theory. In this dissertation, robust stabilization of plants under various classes of structural perturbations using sampled-data controllers is considered. It is shown that a controllable system under bounded perturbations that satisfy certain structural conditions can be stabilized using high-gain sampled-data state feedback control, provided that the sampling period is sufficiently small, with generalizations to decentralized control of interconnected systems. This result is then modified so as to enable adapting the gain and the sampling periods of controllers online. Finally another design methodology is given which enables the controllers to operate on the sampled values of output only, instead of full state measurements.Ocalı, OganPh.D

Decentralized blocking zeros in the control of large scale systems

Ankara : The Department of Electrical and Electronics Engineering and the Institute of Engineering and Science of Bilkent Univ., 1992.Thesis (Ph. D.) -- Bilkent University, 1992.Includes bibliographical references.lu lliis lliesi.s, a luuiiber ot syiithe.sis problems i'or linear. ninc-invariauL, iiiiite-cliuieiiSioiial sysiems are adclres.se(l. It i.s sliown that tlie lu'w concejU of (l·.': m inili zed blocking zeros \s as fmidaineiital to controller .synthesis problems for large scale systems as the concept of decentralized fixed modes. The main problems considered are (i) decentralized stabilization problem, (ii) decentralized strong stabilization problem, and (iii) decentralized concurrent stabilization problem. 7'he dtcenIralized siabUizaiion problem is a fairly well-understood controller synthesis problem for which many synthesis methods exist. Here, we give a new .synthesis procedure via a proper stable fractional approach and focus our attention on the generic solvability and characitnzalion of all solutions. The decenlralized strong .stabilization problem is the problem of stabilizing a .systeni using stable local controllers. In this problem, the .set of decentralized blocking zeros play an essential role and it turns out that the problem has a solution in case tlie poles and the real nonnegative decentralized blocking zeros have parity interlacing property. In the more general problem of decentralized stabilization problem with minimum number of unstable controller poles, it is shown tliat this minimum number is determined by the nuiid.H-»r of odd distributions of plant poles among the real nonnegative decentralized blocking zeros. The decentralized concurrent stabilization problem is a special type of simultaneous stabilization problem using a decentralized controller. Tliis problem is of interest, since many large scale synthesis problems turn out to be its special cases. A complete solution to decentralized concurrent stabilization problem is obtained, where again the decentralized blocking zeros play a central role. Three problems that have receiviHİ wide atteiuion in tlie literature of large scale .systems: stabilization o f composite systems using locally :>tabilizing subsystem controllers, stabilization uf composite system.^ na the slabilization o f mam diagonal transfer matrices, and rcliablt decentralized siabilizaiion problem are solved by a specialization of oiir main result on decentralized concurrent stabilization problem.Ünyelioğlu, Konur AlpPh.D