The Study On Mixed H₂/H_∞ Robust Control Theory And Its Application

H-infinite control is mainly concerned in the robust stability of plants. It can notmeet the needs of some special systems. Mixed H2 / H00 control, which deals withthe robust stability and robust performance, is studied here. Some fruitful results arepresented as follows.An up-bound of the H, norm of system with uncertainty is got by theconditions of quadratic stability of uncertain systems. This up-bound is treated as themixed H2 I H00 performance. This up-bound can be solved by a Riccati equation witha parameter. The minimal point of the up-bound is got by searching over the definearea of the parameter. This method simplifies the procedure of finding mixedH/H~ performance.Several typical mixed H, / H0, control models are proposed. These are fullinformation, full control ,disturbance feed-forward and output estimation. These fourtypical models play the same function as the typical models in H2 or H00 control.The feedback controller design methods of the four models are delivered, that ishelpful for solving the problem of designing output feedback controller.In this dissertation, the inner outer factorization of mixed H2 / H00 controlsystems is discussed. A factorization method is provided. As in the case of H-infinitecontrol, the inner outer factorization of mixed H2 / H00 control keeps the innerstability of systems and the norm of systems.The mixed H2/H00 control problem of plants with different H2 andH00 exogenous inputs and with different H2 and H00 controlled output is studied.This model releases many constrains with respect to the earlier researches. The designmethod of output feedback controller is got for this model.The results we got simplifies the mixed H2 I H00 performance analyses andsystem syntheses, which is helpful in using the mixed H2 I H0, technical intopractical system. In this dissertation, the number of Riccati equations needed forsolving mixed H2 I H00 performance analyses problem, designing the feedbackIIIcontroller of the typical models and designing output feedback controller is equal tothat for solving H2 and H0, control problems. In our case the Riccati equations arewith parameters. The minimum mixed H2 / H~, performance is obtained by searchingthese parameters. Our approach avoids the problem of solving coupled Riccatiequations. The number of Riccati equations used in our approach is also less than thatin earlier methods.The inner relationship of H2 , H0, and mixed H2 /H0, control is discovered.An uniform expression of H2 , H0, and mixed H2 / H0, design approach isdelivered. The Riccati equations we give here for mixed H2 I H0, have the sameforms as for H2 and H~. The only difference is the Riccati equations for mixedH, / H0, with parameters. When the parameters changes, the Riccati equations can bethe same as Riccati equations of H2 or H0, control.The approaches of expressing the nonlinear uncertain flight control model as amixed H2 I H0, system is delivered. A state feedback controller for the fourth-orderlongitudinal dynamic model of a home-made aircraft is designed by the new mixedH2 /H0, design approach given in this dissertation. The simulation response of thefeedback system shows that the new mixed H2 / H0, design approach is effective.ontrol, H0, control, Mixed H /H co220, ntrol,...