Robust Control and Fault Detection Filter Design for Aircraft Pitch Axis

This paper presents a robust control and fault detection filter design for linearized longitudinal dynamics of F-16 aircraft. The control design is based on mu; synthesis method which guarantees the robust performance requirements and takes the structured uncertainty into consideration. In case of F-16 aircraft, it is assumed that an elevator failure and a sensor failure occur during the system operation. To ensure the safety of aircraft control system a fault detection and isolation (FDI) filter is designed. The fault detection filter design based on geometric approach relies on the use of (C,A) invariant subspaces which makes possible the decoupling of different types of failure. Typically, the FDI filter design approach is elaborated for open loop model and it is applied in the closed loop. In this paper the FDI filter designed for aircraft control system will be analyzed for a closed loop system

DESIGN OF LPV CONTROLLERS FOR ACTIVE VEHICLE SUSPENSIONS

In the paper the linear parameter varying (LPV) method is applied to active suspensions. The suspension structure contains nonlinear components, i.e. the dynamics of the dampings and the springs. The model is augmented with weighting functions specified by the performance demands and the uncertainty assumption. By selecting scheduling parameters an LPV model is generated in which the model structure is nonlinear in the parameters but linear in the states. The design of the active suspension is illustrated in the demonstration example

Az elméletileg elérhető legjobb irányítás algoritmusainak kutatása = Investigation of the theoretically reachable best control algorithms

Módszert dolgoztunk ki lineáris, állandó paraméterű folyamatok szabályozási köreiben a beavatkozó szervek és magának a folyamatnak a tulajdonságaiból adódó korlátozásoktól függő határ-optimális szabályozók tervezésére. Algoritmust fejlesztettünk ki a beavatkozó szerv amplitudó korlátozásától függő elérhető legjobb tervezési cél (referencia modell) meghatározására. Megadtuk a nominális és az előző módszerrel kapott optimális referencia modellektől függő optimális szabályozók algoritmusait, amelyek a realizálhatósági veszteséget minimalizálják. Az optimális szabályozókat stabilis folyamatok Youla parametrizált szabályozási köreire határoztuk meg. Az optimalitás kritériumaként a H2, Hinf és L2, Linf normákat alkalmaztuk. A realizálhatósági veszteség H2, L2 normák szerinti optimalitását a szabályozók - speciális Diofantoszi egyenletek alapján számolt - belső szűrőinek felhasználásával biztosítottuk. A realizálhatósági veszteség Hinf, Linf normák szerinti optimalitását a szabályozók - speciális Nevanlinna-Pick approximációs egyenletek alapján számolt - belső szűrőinek alkalmazásával biztosítottuk. A H2, Hinf normák alkalmazásával csak nem integráló optimális szabályozó nyerhető. Optimális integráló szabályozóhoz az eredeti normákat speciális ""energia"" illetve ""supremum"" normákká kellett kiegészíteni az L2, Linf normák egyidejű alkalmazásával és nem Dirac-delta alakú gerjesztés feltételezésével. Új iteratív módszert vezettünk be a modellezési veszteség optimalizálására is. | A new method was developed for design of the (reachable) best controllers for LPI processes when the activator has an amplitude constraint and the process has invariant properties. A procedure was suggested to compute the best (reachable) reference model for tracking and disturbance rejection. A new approach was introduced to minimize the realizability degradation part of the sensitivity function using nominal process models. This optimization uses Youla parametrized regulators for open-loop stable plants. H2, Hinf and L2, Linf norms are used in this procedure. The H2, L2 norm based optimization uses special Diophantine equation to calculate the optimal embedded filter in the regulators. The Hinf, Linf norm based optimization uses special Nevanlinna-Pick approximation to calculate the optimal imbedded filter in the regulators. The original norm formulation was used in a combined way forming general ''energy'' and ''supremum'' norms assuming higher order excitations than the Dirac-delta to ensure integrating optimal regulators, too. New iterative algorithm was developed to minimize the modeling degradation part of the sensitivity function

Lineáris paraméter változós rendszerek modellezése és átkonfigurálható irányítása = Modeling and reconfigurable control of LPV systems

A Lineráris ParaméterVáltozós (LPV) rendszerek alkalmazása különösen légi és földi járművek modellezési és irányítási feladatainak megoldásában vált nagy jelentőségüvé. Ezek a rendszerek nemlineáris, időfüggő dinamikájúak és az LPV modellezési paradigma lehetőséget ad a geometriai rendszerelmélet, valamint a robusztus irányítások lineáris és affin nemlináris módszertanának alkalmazására. A kutatási program során sikerült megalapozni az LPV rendszerek geometriai elméletét és több olyan algoritmust dolgoztunk ki amellyel rendszer analízis, hibadetektálás irányítás és átkonfigurálás megoldható. Az eredmények összefoglalását a 16th IFAC Wordcongress (2005) szemiplenáris előadása keretében számoltunk be, az eredményeket mind földi, mint repülőgép irányítási rendszerek tervezénél bemutattuk. Ez utóbbira a University of Minnesota Aerospace and Mechanics tanszékével közös kutatás keretén belül került sor, az eredményeket folyóiratokban és konferencia kiadványokban publikáltuk. | Linear Parameter Varying (LPV) systems gained an increasing importance in the area of road and aerial vehicle modelling and control system design. These systems can be described by complex nonlinear and time-varying dynamics and the use of LPV modeling paradighms allows the designer to use results from geometric theory and robust control methods elaborated for linear certain nonlinear afine control systems. This research program resulted in the elaboration of the foundations of a geometric system theory for LPV systems and this lead to the implementation of new algorithms to solve analysis and design problems associated to fault detection, controller design and control system reconfiguration for certain class of time varying and nonlinear systems. A summary of the research results was made public in the form of a semiüplenary lecture at the 16th IFAC Word Congress (2005) and the results were also veryfied in the desig of control systems for road and aerial vehicles. The research associated to the aerial vehicles was performed togethet with researchers on the Department of Aerospace and Mechanics, University of Minnesota, Minneapolis

MIXED H2/H∞ CONTROL DESIGN FOR ACTIVE SUSPENSION STRUCTURES

This paper presents the mixed H2/H∞ synthesis for active suspension design. The compensator is designed in such a way that it minimizes a given H2 performance function, which keeps the maximum supported H∞ perturbation below appropriate levels. In this design problem, the aim is to find a set of values for the design variables that yield an optimum value of the objective (or cost) function and which fit a number of constraints. In order to solve this problem a design procedure based on a trade-off curve is presented

Professional women musicians in early eighteenth-century Württemberg

The mixed μ synthesis is proposed for mechanical systems. In this method, both the real parametric and the complex uncertainties are handled together. A compensator that achieves nominal performance and meets robust stability specifications can be designed. The method will be illustrated for an inverted pendulum device as an educational example and a suspension design problem as a practical example

Cell Contact–dependent Regulation of Epithelial–Myofibroblast Transition via the Rho-Rho Kinase-Phospho-Myosin Pathway

Epithelial-mesenchymal-myofibroblast transition (EMT), a key feature in organ fibrosis, is regulated by the state of intercellular contacts. Our recent studies have shown that an initial injury of cell–cell junctions is a prerequisite for transforming growth factor-β1 (TGF-β1)-induced transdifferentiation of kidney tubular cells into α-smooth muscle actin (SMA)–expressing myofibroblasts. Here we analyzed the underlying contact-dependent mechanisms. Ca(2+) removal–induced disruption of intercellular junctions provoked Rho/Rho kinase (ROK)-mediated myosin light chain (MLC) phosphorylation and Rho/ROK-dependent SMA promoter activation. Importantly, myosin-based contractility itself played a causal role, because the myosin ATPase inhibitor blebbistatin or a nonphosphorylatable, dominant negative MLC (DN-MLC) abolished the contact disruption-triggered SMA promoter activation, eliminated the synergy between contact injury and TGF-β1, and suppressed SMA expression. To explore the responsible mechanisms, we investigated the localization of the main SMA-inducing transcription factors, serum response factor (SRF), and its coactivator myocardin-related transcription factor (MRTF). Contact injury enhanced nuclear accumulation of SRF and MRTF. These processes were inhibited by DN-Rho or DN-MLC. TGF-β1 strongly facilitated nuclear accumulation of MRTF in cells with reduced contacts but not in intact epithelia. DN-myocardin abrogated the Ca(2+)-removal– ± TGF-β1–induced promoter activation. These studies define a new mechanism whereby cell contacts regulate epithelial-myofibroblast transition via Rho-ROK-phospho-MLC–dependent nuclear accumulation of MRTF