كنترل وفقي دسته اي از سيستمهاي غير خطي نامعين با پارامترهاي متغير با زمان در حضور سيگنالهاي اختلال

چكيده انگليسي :

AbstractIn this dissertation robust adaptive control of uncertain nonlinear systems in the presence ofdisturbances is considered as an important topic in the field of control Time varyingparametric uncertainty which may manifest itself in such applications as robotic systems marine and submarine vehicles and chaotic systems is incorporated into the so calledfeedback linearizable systems Due to system uncertainties the conventional nonlinearcontrol methods such as feedback linearization may fail On the other hand conventionaladaptive control is unable to tackle time varying parameters with arbitrarily fast variations Furthermore disturbance signals may also cause undesired performance Due to these facts two robust adaptive algorithms are proposed here to tackle such perturbations The firstmethod attenuates the effect of disturbance at the output or equivalently satisfies an H tracking performance Since some disturbances do not belong to L2 space required in thefirst method the other adaptive based algorithm is developed to reject disturbances withunknown bounds Compared with some previous investigations in the proposed methods theassumptions made on the system are more easily satisfied the upper bound of perturbationsare not required in the design procedure and the control algorithms are extended to multipleinput multiple output MIMO systems As an application chaos synchronization problem is solved with the aid of the proposedcontrol scheme An uncertain unified chaotic system is considered as a MIMO nonlinearsystem The synchronization algorithm is developed for the aforementioned system and somesimulation results are also demonstrated to show the effectiveness of the method Key WordsRobust adaptive control Time varying parameters Uncertain nonlinear systems Disturbancerejection IntroductionTracking control for uncertain nonlinear systems is one of the main topics in the field ofcontrol theory The assumptions made on the system uncertainties motivate researchers topropose various tracking control methodologies In particular considerable attention is paidto tackle the nonlinear systems with unknown parameters Depending on the assumptionsmade on parametric uncertainties and unknown disturbances various control schemes havebeen reported in the last several years 1 3 Among the reported methods adaptive basedcontrol techniques are powerful tools especially when the variations of unknown parametersare slow enough From a historical point of view adaptive control algorithms were firstdeveloped for uncertain systems with unknown but constant parameters In fact conventionaladaptive methods including adaptive control laws together with some parameter adjustingmechanisms may fail for the case of arbitrarily fast time varying perturbations Investigatinginto this field several results have been reported when the time varying parameters ordisturbances are periodic 2 4 For the case of non periodic parameters most of reportedcontrol techniques require an upper bound of uncertainty for controller design In practice external disturbances may also affect the performance of dynamical systems Twomajor techniques are investigated to deal with this problem disturbance attenuation anddisturbance rejection The first policy is mostly considered if the bound of disturbance signalis unknown The robust H control method has been widely used to attenuate the influenceof disturbance in this case 5 These conventional H control techniques however wouldmeet some difficulties if the plant model has large uncertainties Moreover in these controlschemes the disturbance signal is implicitly assumed to belong to the L2 space Concerningwith the rejection purpose several adaptive approaches have been introduced for the case of

كوفيگر، حميدرضا

كنترل وفقي دسته اي از سيستمهاي غير خطي نامعين با پارامترهاي متغير با زمان در حضور سيگنالهاي اختلال

حذف اثر اختلال , فرم خطي پذير , شبيه سازي