Inversion Based Robust Two Degree Of Freedom Control Approach Reasearch

Two-degree-freedom control approach has been wildely used in tracking controlsystems, such as nanopositioning actuator, hard disk and optical disk drive servo system,and so on. With the rapid development of nanotechnology, hard disk and optical diskindustrial, the requirements for position tracking control system become higher andhiger. Now, the research on high performance two-degree-freedom control approach hasbeen drawning more and more attention.Inversion-based control technology, utilizes the desired tracking signal informationand the non-casual inverse of system model to compute a bounded inverse input toachieve a precision signal tracking. However, because of the adverse effect of systemuncertainty and external disturbance, the inversion-based control is limited to enhancethe tracking control performance of system with uncertainties. To achieve highperformance tracking control of uncertain system, it is very important to study thecontrol approach which combines the inversion-based control and two-freedom-degreecontrol approaches.Aiming to the tracking control and performance optimization problems of systemwith uncertainties, this paper studies the inversion-based robust two-degree-freedomcontrol approach intensively, the main research work is listed as follow,1. Aiming to the H_∞tracking performance optimization problem of system withparameter uncertainty, a H_∞optimal inversion feedforward and robust feedback basedtwo-degree-freedom control approach is proposed. By using LMI optimization approachand introducing a modification function into inversion-based feedforward controllerdesign, a H_∞optimal inversion feedforward controller which could minimize thefeedforward tracking error effected by the system uncertainty is obtained. Asystematical robust feedback controller design approach which fully considers thefeedforward controller and system performance requiremts is presented.2. Aiming to the mixed H₂/H_∞tracking performance optimization problem ofuncertain system, a mixed H₂/H_∞robust two-degree-freedom control approach isproposed. A H₂optimal inversion feedforward design method based on improved H₂ LMI representation which is suitable for the H₂synthesis of uncertain system ispresented. A H₂/H_∞LMI representation for feedback controller design and the optimalfeedback controller design procedure is proposed.3. Aiming to the disturbance rejection and tracking control precision problem ofsystem with uncertainty, an internal model based robust inversion feedforward andfeedback two-degree-freedom control approach is proposed. The proposed approachcombines the internal model control theory and inversion-based two-degree-freedomcontrol approach to improve system rejection ability and tracking control precision.The optimal internal model based disturbance compensator and robust inversionfeedforward controller design approach based on LMI optimization are proposed. Therobust feedforward controller design approach which fully considers the adverse effectcaused by external disturbance and system requirements is also presented.4. Aiming to the tracking control problem of MIMO system with additiveuncertainty, an inversion based MIMO robust two-degree-freedom control approach isproposed. The proposed approach combines the robust diagonal dominance based staticprecompensation and two-degree-freedom control to improve the tracking performanceof MIMO system. The main contribution of the proposed approach is an extension ofrobust inversion design for SISO system to MIMO system and a systematic integrationof H_∞mixed sensitivity robust MIMO feedback control and inversion-basedfeedforward control.