1,720,968 research outputs found
A robust constrained model predictive control scheme for norm-bounded uncertain systems with partial state measurements
No full textA robust model predictive control scheme for a class of constrained norm-bounded uncertain discrete-time linear systems is developed under the hypothesis that only partial state measurements are available for feedback. The proposed strategy involves a two-phase procedure. Initialization phase is devoted to determining an admissible, though not optimal, linear memoryless controller capable to formally address the input rate constraint; then, during on-line phase, predictive capabilities complement the designed controller by means of N steps free control actions in a receding horizon fashion. These additive control actions are obtained by solving semidefinite programming problems subject to linear matrix inequalities constraints. As computational burden grows linearly with the control horizon length, an example is developed to show the effectiveness of the proposed approach for realistic control problems: the design of a flight control law for a flexible unmanned over-actuated aircraft, where the states of the flexibility dynamics are not measurable, is discussed, and a numerical implementation of the controller within a nonlinear simulation environment testifies the validity of the proposed approach and the possibility to implement the algorithm on an onboard computer
An hybrid command governor supervisory scheme for flight control systems subject to unpredictable anomalies
No full textIn this paper, we develop a hybrid supervisory control architecture in a real-time environment for constrained control systems. The strategy is based on Command Governor (CG) ideas and is tailored to jointly take into account time-varying set-points/constraints and unpredictable anomalies in the nominal dynamical plant behaviour. The significance of the method mainly lies in its capability to avoid constraint violation and loss of stability regardless of any configuration change occurrence in the plant/constraint structure by commuting the current CG with a new on-line computed unit. Simulations on an High Altitude Performance Demonstrator (HAPD) unmanned aircraft with redundancy control surfaces show the effectiveness of the proposed strategy. © 2013 IEEE
A norm-bounded robust MPC strategy with partial state measurements
No full textIn this paper a robust MPC scheme based on a partial-state availability is developed for uncertain discrete-time linear systems described by structured norm-bounded model uncertainties and subject to saturation and rate of variation constraints. The algorithm is based on the minimization, at each time instant, of a semi-definite convex optimization problem subject to Linear Matrix Inequalities (LMI) feasibility constraints which are derived by a judicious use of S-Procedure arguments. Numerical comparisons with competitor algorithms are finally reported by dealing with the control augmentation problem of an High Altitude Performance Demonstrator (HAPD) unmanned aircraft with redundant control surfaces
A reconfigurable aircraft control scheme based on an hybrid Command Governor supervisory approach
No full textIn this paper, we adopt the hybrid supervisory control architecture developed in [1] for constrained control systems. The strategy is based on Command Governor (CG) ideas and is tailored to jointly take into account time-varying set-points/constraints and unpredictable anomalies in the nominal dynamical plant behaviour. The main contribution is to develop a low-computational demanding predictive scheme known in literature as the command governor (CG) for the supervision of non- linear dynamical systems subject to sudden switchings amongst operating conditions and time-varying constraints by preserving its basic properties. In order to show the effectiveness of proposed approach, we show significant simulations on the P92 commercial aircraft used for general aviation purposes. © 2014 American Automatic Control Council
Embedding norm-bounded Model Predictive Control allocation strategy for the High Altitude Performance Demonstrator (HAPD) Aircraft
No full textIn this paper the implementation of a robust Model Predictive Control (MPC) algorithm for constrained uncertain discrete-time linear systems subject to norm-bounded model uncertainties is used to deal with the control allocation problem of an High Altitude Performance Demonstrator (HAPD) unmanned aircraft with redundancy control surfaces. Specifically, the HAPD nonlinear model is described by means of LFR differential inclusions achieved via embedding arguments while the surface deflection amplitude limitations are formulated in terms of convex constraints. As a consequence, the overall control problem can be recast in terms of Linear Matrix Inequalities (LMIs) that are affordable from a computational point of view. © 2013 IEEE
A hybrid real-time supervisory scheme for nonlinear systems
No full textIn this paper we develop a hybrid supervisory control architecture in a real-time environment for constrained nonlinear systems. The strategy is based on Command Governor (CG) ideas that are here specialized in order to take into account both time-varying set-points and constraints. Experimental results on a laboratory four-tank test-bed are presented. © 2011 AACC American Automatic Control Council
A Hybrid Real-Time Command Governor Supervisory Scheme for Constrained Control Systems
No full textIn this paper, we develop a hybrid supervisory control architecture in a real-time environment for constrained control systems. The strategy is based on Command Governor (CG) ideas that are here specialized to consider both time-varying set-points and constraints. The significance of the method mainly lies on its capability to avoid constraints violation and loss of stability regardless of any configuration change occurrence in the plant/constraint structure by replacing the current CG with a new on-line computed unit. A real-time scheme is an extremely appealing choice because of its numerous engineering applications: automobile industry, defense and aerospace, chemical and nuclear plant applications, multimedia/telecommunications, and so on. Experimental results on a laboratory four-tank test-bed and simulations on a Cessna 182 aircraft model show the effectiveness of the proposed strategy
A Safe Supervisory Flight Control Scheme in the Presence of Constraints and Anomalies
No full textIn this paper the hybrid supervisory control architecture developed by Famularo et al. (2011) for constrained control systems is adopted with the aim to improve safety in aircraft operations when critical events like command saturations or unpredicted anomalies occur. The capabilities of a low-computational demanding predictive scheme for the supervision of non-linear dynamical systems subject to sudden switchings amongst operating conditions and time-varying constraints are exploited in the flight control systems framework. The strategy is based on command governor ideas and is tailored to jointly take into account time-varying set-points/constraints. Unpredictable anomalies in the nominal plant behaviour, whose models fall in the category of time-varying constraints, can also be tolerated by the control scheme. In order to show the effectiveness of the proposed approach, simulations both on a high altitude performance demonstrator unmanned aircraft with redundant control surfaces and the P92 general aviation aircraft are discussed
Going Beyond Counting First Authors in Author Co-citation Analysis
Full text linkThe present study examines one of the fundamental aspects of author co-citation analysis (ACA) - the way co-citation
counts are defined. Co-citation counting provides the data on which all subsequent statistical analyses and mappings
are based, and we compare ACA results based on two different types of co-citation counting - the traditional type that
only counts the first one among a cited work's authors on the one hand and a non-traditional type that takes into
account the first 5 authors of a cited work on the other hand. Results indicate that the picture produced through this non-traditional author co-citation counting contains more coherent author groups and is therefore considerably clearer. However, this picture represents fewer specialties in the research field being studied than that produced through the traditional first-author co-citation counting when the same number of top-ranked authors is selected and analyzed. Reasons for these effects are discussed
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