Passive fault tolerant perfect tracking with additive faults

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We strengthen the existing definition of (J, J ′ )-lossless rational matrices (RMs) and find an algebraic characterization of the newly defined class of strongly (J, J ′ )-lossless RMs. The algebraic characterization is given for possibly improper RMs. A connection is presented to a rational ℋ ∞ problem, known as the Leech problem, which is elaborated on with necessary and sufficient conditions, given in terms of the strongly (J, J ′ )-lossless property, as an alternative of the Leech conditions, which can be expressed with positivity of a kernel. An algorithm for solving the Leech problem is given and illustrated by examples. KEYWORDS robustness, robust control, (J, J ′ )-lossless rational matrix, ℋ ∞ problem Int J Robust Nonlinear Control. 2018;28:4261-4286.wileyonlinelibrary.com/journal/rnc

“…(I)⇒(II). The existence of the matrices P 1 and P 2 satisfying (25)- (27) is a consequence of Lemma 1, where the essential condition is (21), and of identity (12).…”

Section: Assumptionmentioning

confidence: 97%

“…The problem of fault tolerant control is an important control problem, without a definite solution. 11 One approach is to use a solution of the Leech problem, as in the work of Stefanovski, 12 where a passive fault tolerant perfect tracking is elaborated on. 4.…”

Section: Introductionmentioning

confidence: 99%

Strongly (J,J′)‐lossless rational matrices and ℋ_∞ problem

Stefanovski

2018

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“…A brief review of the problem of perfect tracking with disturbance decoupling is given in Reference . A control algorithm, applied on aircrafts, is given in section 5.4 of Reference .…”

Section: Introductionmentioning

confidence: 99%

“…The approach of disturbance decoupling has been applied in Reference to fault‐tolerant perfect tracking, however, with the restrictive assumption that matrix D 12 = G 12 (∞), where G 12 is the transfer matrix from the control input to the controlled output, has full row rank. The assumption rules out the case with no constraint on the control in the performance criterion, that is, D 12 =0.…”

Section: Introductionmentioning

confidence: 99%

See 1 more Smart Citation

Almost fault‐tolerant tracking

Stefanovski

2020

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Summary A new formulation of the problem of almost fault‐tolerant perfect tracking in presence of disturbances is presented, and necessary and sufficient existence conditions are found, as well as a controller, which consists of a feedback block and two feedforward blocks. The feedback block is aimed for almost disturbance and fault decoupling, and the feedforward blocks are aimed for almost perfect tracking. A two‐step control design procedure such that the feedback block is designed independently of the feedforward blocks is presented. In order to simplify the necessary and sufficient existence conditions, as well as to present a physical interpretation of the existence conditions, the dimension of disturbance and fault vectors is reduced. In order to find a feedback controller, the physical interpretation of the existence conditions is used so that the four‐block‐type problem is transformed to a two‐block‐type problem. Examples are given, which illustrate that the controller of the article is practically realizable.

Hierarchical robust control for variable‐pitch wind turbine with actuator faults

Ameli

Anubi

2022

In this brief, we develop a fault tolerant control (FTC) using a hierarchical-robust methodology with guaranteed stability for a wind turbine (WT), which is subject to an exogenous input and an actuator fault. The high-level control is designed to robustly compensate for the nonlinearities, uncertainty, and disturbance in the system. The low-level control is designed to robustly automatically allocate control authority among redundant actuators mitigating an actuator fault. At the low-level, the robust control problem is transformed into an equivalent optimal control problem. Finally, the developed FTC is validated using a comprehensive simulation study on a 5 MW variable-pitch WT model given in the Fatigue, Aerodynamics, Structures, and Turbulence (FAST) simulator provided by the U.S. National Renewable Energy Laboratory (NREL). The results show that the developed FTC retains robust performance in the presence of wind disturbance and a time-varying actuator fault.