The Infona portal uses cookies, i.e. strings of text saved by a browser on the user's device. The portal can access those files and use them to remember the user's data, such as their chosen settings (screen view, interface language, etc.), or their login data. By using the Infona portal the user accepts automatic saving and using this information for portal operation purposes. More information on the subject can be found in the Privacy Policy and Terms of Service. By closing this window the user confirms that they have read the information on cookie usage, and they accept the privacy policy and the way cookies are used by the portal. You can change the cookie settings in your browser.
Parameter estimation problem in dynamical systems can be addressed using the static adaptive observers to generate parameter estimates on line. However, if such estimates are used in a certainty equivalence adaptive control (CEAC) law, the stability problem arises. In this paper it is shown that the CEAC law, in which parameter estimates are generated using static observers and several adaptive laws...
A systematic design procedure using state-feedback Certainty Equivalence Adaptive Control (CEAC) technique is developed for linear plants and a class of nonlinear plants with unmatched uncertainty. It is shown that a reduced order observer and adaptive laws with normalization in conjunction with the CEAC law result in a stable overall system in the case of linear plants of any relative degree, and...
A systematic design procedure using state-feedback certainty equivalence adaptive control (CEAC) technique is developed for linear plants and a class of nonlinear plants with unmatched uncertainty. It is shown that a reduced order observer and adaptive laws with normalization in conjunction with the CEAC law result in a stable overall system in the case of linear plants of any relative degree, and...
In many practical situations uncertain plants are such that the unknown parameters do not affect the entire state of the system, but only some of the state variables. A question that arises in this context is the following: can a reduced-order adaptive observer be designed based only on the part of the dynamics affected by the uncertainty, such that, when the corresponding parameter estimates are...
This paper presents a bounded linear stability analysis for a hybrid adaptive control that blends both direct and indirect adaptive control. Stability and convergence of nonlinear adaptive control are analyzed using an approximate linear equivalent system. A stability margin analysis shows that a large adaptive gain can lead to a reduced phase margin. This method can enable metrics-driven adaptive...
In this paper an initial study is presented regarding a new combined robust and adaptive control approach to fault-tolerant flight control. The approach is based on designing a suitable tracking-error feedback (TEF) term such that the plant is stabilized over the entire uncertainty set. If such a term can be found, the adaptive control part depends only on the reference model state and the reference...
A failure detection, identification and reconfiguration (FDIR) control scheme is developed for a dynamic model of the delta clipper-experimental (DC-X) single stage to orbit rocket concept. The six degree of freedom, redundantly actuated model provides a well-suited test case for designing a fault-tolerant controller for actuators with different response rates, the reconfigurable controller maintains...
In this paper a new approach to adaptive fault-tolerant control with self-diagnostics is presented. The approach is based on generating high-frequency signals for actuators with suspected failures, and minimizing the effect of those signals on the system state using the remaining healthy control surfaces. It is shown that the adjustment of parameters using a signal composed of the nominal control...
Most available approaches for adaptive accommodation of failures in flight control actuators result in a large number of parameters that need to be adjusted on-line. In this paper we propose a new failure parameterization that models a large class of failures in terms of a single parameter. The class of failures includes lock-in-place (LIP), float, hard- over and loss of effectiveness (LOE). It is...
In this paper effective failure detection, identification and reconfiguration (FDIR) algorithms are developed for a class of nonlinear systems characterized by significant actuator dynamics. Assuming that the actuator dynamics are fast, a baseline controller is designed and, using the singular perturbation arguments, shown to achieve the control objective. Typical failures in flight control actuators...
Set the date range to filter the displayed results. You can set a starting date, ending date or both. You can enter the dates manually or choose them from the calendar.