quotFeedback Control Design For Computing Serverquot

Abstract

Cyber physical systems involve computer application to physical dynamic newlinesystems under variable load, resource changes and possibly system fault newlineconditions. In such cases, there is a need to consider the dynamic performance newlineof the computer server as opposed to the traditional steady state operation of newlinethe system in an open loop configuration. IBM has envisaged a new control newlineparadigm called MAPE-K loop which stands for monitor, analyse, plan, newlineexecute and knowledge. The MAPE-K loop proposes to apply control newlineconcepts in order to make software and computing systems self-adaptive. newlineSince the IBM initiative, control theory has been proposed to solve the newlineproblems of software systems operating a physical system subject to external newlinedisturbances such as in a cyber physical system. Various researches have been newlinereported applying feedback control to improve the dynamic performance of newlinecomputing system. In this thesis, we model a computer server system as a discrete event system newlineusing Simevents and Simulink modules in a novel way. Different control newlinearchitectures are imposed on the Matlab Simulink model to analyse their newlineapplication to server control. Firstly, two interacting loops are identified in the newlinecomputer server system. A compensator is designed to decouple the control newlineloops in the server system. Simevent Simulink simulation of the server control newlinesystem illustrates the performance that can be obtained through feedback and newlinedecoupling. A stability analysis of the decoupled system is provided to support newlinethe experimental results. Further, considering the 2x2 server control system, newlineindividual channel design (ICD) approach allows independent controller newlinedesign of the two loops. Theoretical analysis of the robust stability of the ICD newlinedesign is carried out based on the multivariable structure function property. Simulation results are provided to validate the proposal of diagonal control of newlinecomputer server together with the demonstration of its robust performance. newline