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Littérature scientifique sur le sujet « Robust stability (margins) and performance »

Auteur : Grafiati
Publié le 25 janvier 2025

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Articles de revues sur le sujet "Robust stability (margins) and performance"

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Pourseiedrezaei, Mehdi, Mohammad Bozorg et Ali Delavar-Khalafi. « Application of Two Polynomial Optimization Methods for Computing Robust Stability and Robust Performance Margins ». IFAC Proceedings Volumes 44, no 1 (janvier 2011) : 7690–95. http://dx.doi.org/10.3182/20110828-6-it-1002.02974.

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Al-Shamali, Saleh A., Haniph A. Latchman, Baowei Ji et Oscar D. Crisalle. « A Margin for Robust Stability and Robust Performance ». IFAC Proceedings Volumes 36, no 11 (juin 2003) : 335–40. http://dx.doi.org/10.1016/s1474-6670(17)35686-0.

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Abdulsada, Abdullah, et Nasir Selman. « Robust digital voltage mode control of buck converter with enhanced tracking performance ». Al-Qadisiyah Journal for Engineering Sciences 17, no 2 (30 juin 2024) : 158–64. http://dx.doi.org/10.30772/qjes.2024.145861.1076.

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The digital voltage controller of power converters is used because it has many advantages over its analog counterparts. Thus, in this paper, a controller of digital voltage mode is designed and analyzed for a non-isolated DC-DC buck converter in continuous conduction mode (CCM). First, an analog controller is designed using a Bode plot to achieve the desired stability margins in the frequency domain. Next, the analog controller is discretized using bilinear transformation with the pre-warping method. The characteristics of the discretized compensator can be maintained close to the corresponding analog compensator as long as a proper sampling time is selected. The digital control scheme is simulated with a nonlinear DC-DC buck converter model in MATLAB/Simulink to investigate the controller performance. The simulation results demonstrated the validation of the proposed digital voltage-mode control design approach. The developed digital controller eliminates DC error by tracking the reference voltage, achieving a fast transient response, maintaining specified stability margins, and effectively rejecting large disturbances.
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Gopi, Pasala, Pinni Srinivasa Varma, Ch Naga Sai Kalyan, C. V. Ravikumar, Asadi Srinivasulu, Bhimsingh Bohara, A. Rajesh, Mohd Nadhir Bin Ab Wahab et K. Sathish. « Dynamic Behavior and Stability Analysis of Automatic Voltage Regulator with Parameter Uncertainty ». International Transactions on Electrical Energy Systems 2023 (25 janvier 2023) : 1–13. http://dx.doi.org/10.1155/2023/6662355.

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This research article describes a novel optimization technique called simulink design optimization (SDO) to compute the optimal PID coefficients for an automatic voltage regulator (AVR). The time-domain performance of the proposed controller was analyzed using MATLAB/Simulation, and its performance was compared with that of water cycle algorithm, genetic algorithm, and local unimodal sampling algorithm-based PID controllers. The robustness of the proposed controller was verified by applying the disturbances to the generator field voltage and the amplifier parameter uncertainty. The studies presented in literature were discussed the AVR loop stability using the Bode plot which will not give the minimum stability margins. This study proposes a novel stability analysis called disk-based stability analysis to authenticate the stability of the AVR loop which is obtained by the classical analysis. This stability was compared with the proposed stability analysis. The MATLAB results reveal that the SDO-PID controller regulates the terminal voltage of the generator precisely, is more robust to parameter uncertainty, and is more stable than the other controllers. The maximum allowable parameter uncertainty of the amplifier model was identified as 102% of its nominal parameters. The stability margins are recognized as DGM = 10.40 dB and DPM = 56.50° for the AVR stability.
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Hasanvand, Hamed, et Mohammad Reza Zamani. « Robust control of static Var compensator-based power oscillation dampers using polynomial control in power systems ». Transactions of the Institute of Measurement and Control 40, no 5 (24 janvier 2017) : 1395–406. http://dx.doi.org/10.1177/0142331216683774.

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A static Var compensator (SVC) installed in a power transmission network can be effectively exploited to enhance the damping of low frequency electromechanical oscillations. The application of robust control theory offers more reliable and robust damping controller to achieve desired damping level considering variations in the operating conditions of power system. This paper presents a new approach to design a robust proportional-integral (PI) controller for stabilizing power system oscillations. The variability in operating conditions is captured using an interval polynomial and then, Kharitonov’s theorem is used to design the desired damping controller. The proposed method is based on plotting the stability boundary locus in the ( kp-ki) plane and then computing the stabilizing values of the parameters of a PI controller. Besides stabilization, computation of stabilizing PI controllers that achieve user specified gain margin (Gm), phase margin (Pm) and bandwidth is studied simultaneously. This novel method enables designers to make the convenient trade-off between stability and performance by choosing the proper margins and bandwidth specifications. In addition, the most appropriate stabilizing input signal is selected using Hankel singular value (HSV) and right half plane-zeros (RHP-zeros) for the SVC-based supplementary damping controller. The effectiveness and robustness of the proposed controller are demonstrated using eigenvalue analysis and time-domain simulation for a 16 machine 68-bus test system. The simulations and analysis are implemented in matrix laboratory environment and power system analysis toolbox.
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Halbe, Omkar, Tim Mehling, Manfred Hajek et Milan Vrdoljak. « Synthesis and Piloted Evaluation of Advanced Rotorcraft Response Types Using Robust Sliding Mode Control ». Journal of the American Helicopter Society 66, no 3 (1 juillet 2021) : 1–20. http://dx.doi.org/10.4050/jahs.66.032008.

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Sliding mode control (SMC) is a promising technique for robust control synthesis with desirable properties. This paper describes the synthesis and piloted evaluation of advanced helicopter response types using the SMC technique. The required closed-loop response characteristics are specified as ideal, lower order, axial transfer functions that conform to predicted level 1 handling qualities. Two-loop, full-authority, output-tracking SMC laws are then synthesized to enforce the closed-loop performance and accurately track pilot commands. Analytical proofs for SMC gain tuning are given for the closed-loop performance to remain robust to unknown but bounded uncertainties in the input channels and the effects of rotor modes on closed-loop stability. The closed-loop eigenstructure is nearly identical to the specified closed-loop performance and has good modal decoupling. Furthermore, a frequency domain analysis with a nonlinear helicopter model shows good stability margins and disturbance rejection characteristics. Finally, the paper reports on simulation testing conducted with four experimental test pilots in a rotorcraft simulation environment. The simulation results indicate improved mission task performance and handling qualities ratings and a substantial reduction in pilot workload for the SMC-based advanced response types compared to the bare-airframe responses.
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Yeh, Syh-Shiuh, et Pau-Lo Hsu. « Theory and Applications of the Robust Cross-Coupled Control Design ». Journal of Dynamic Systems, Measurement, and Control 121, no 3 (1 septembre 1999) : 524–30. http://dx.doi.org/10.1115/1.2802506.

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The cross-coupled control (CCC) has been recognized as an efficient motion controller that reduces contouring errors, but theoretical analysis of it is lacking, and there is no systematic design approach for obtaining a CCC system with guaranteed control performance. Consequently, the compensators C in CCC are commonly implemented in a PID structure and their contouring accuracy is usually degraded in real applications under different operating conditions. In an attempt to overcome the CCC design limitations described above, this paper introduces a robust CCC design based on a novel formulation: the contouring error transfer function (CETF), leading to an equivalent formulation as in the feedback control design problem. Then, methods in robust control design can be readily employed to achieve robust CCC with specified stability margins and guaranteed contouring performance. Furthermore, the proposed design has been verified as being internally stable. All provided experimental results indicate that the proposed robust CCC design consistently renders satisfactory contouring accuracy under different operating conditions.
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S. Kumar, Supanna, C. Shreesha et N. K. Philip. « Robust PID controller design for rigid uncertain spacecraft using Kharitonov theorem and vectored particle swarm optimization ». International Journal of Engineering & ; Technology 7, no 2.21 (20 avril 2018) : 9. http://dx.doi.org/10.14419/ijet.v7i2.21.11825.

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This paper presents a robust Proportional Integral Derivative controller design methodology for three axis attitude control of a rigid spacecraft with parametric uncertainty using a combination of Kharitonov theorem and vectored particle swarm optimization based approaches. A controller is designed for each of the three axes using a systematic graphical approach. Here, a plot of the stability boundary loci in the integral gain versus proportional gain parameter plane, for the specified gain and phase margins for each of the Kharitonov interval plants is used to determine the region representing the set of all PID controllers that satisfy the desired performance and stability requirements. Vectored particle swarm optimization technique is used to determine the optimized proportional and integral gain values. The spacecraft attitude control system is simulated using Matlab-Simulink tool which shows that the designed controller provides stability, robustness, good reference pointing and disturbance rejection for perturbations within the specific bounds.
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Wang, Yuan-Jay. « A Robust FOPD Controller That Allows Faster Detection of Defects for Touch Panels ». Mathematical and Computational Applications 29, no 2 (16 avril 2024) : 29. http://dx.doi.org/10.3390/mca29020029.

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This study aims to synthesize and implement a robust fractional order PD (RFOPD) controller to increase the speed at which defects in automated touch panel inspection systems (ATPISs) are detected. A three-dimensional orthogonal stage (TDOS) driven by BLDC servo motors moves the inspection pen (IP) vertically and horizontally. The dynamic equation relating the BLDC servo motor input to the tip motion is established. A touch position identification (TPI) system is used to locate the touch point rapidly. An RFOPD controller is used to actuate the BLDC servo motors and move the TDOS rapidly and accurately in three dimensions. This method displaces the IP to any specified position and shows user-defined inspection trajectories on the touch screens. The gain-phase margin tester (GPMT) and stability equation methods are exploited to schedule the RFOPD controller gain settings and to maintain the specific safety margins for the controlled system. The simulation studies show that the proposed RFOPD controller exhibits better tracking and disturbance rejection responses than a conventional PID controller. The robustness of the RFOPD-controlled ATPIS, considering unmodeled uncertainties and friction-induced disturbances, is verified through simulation and experimental studies. Several user-defined inspection patterns are used to verify performance, and the experimental results show that the proposed RFOPD controller is effective.
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Sedraoui, M., T. Amieur, R. Bachir Bouiadjra et M. Sahnoune. « Robustified fractional-order controller based on adjustable fractional weights for a doubly fed induction generator ». Transactions of the Institute of Measurement and Control 39, no 5 (16 novembre 2016) : 660–74. http://dx.doi.org/10.1177/0142331215617236.

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In this paper, a robustification method of the primary fractional controller is proposed. This novel method uses the adjustable fractional weights on the H∞ mixed-sensitivity problem. It can achieve an enhancement in both nominal performance and robust stability margins for the uncertain plants while respecting the frequency-domain constraints, such as the tracking of the set-point references, load disturbance attenuation and measurement noise suppression. The proposed robustification holds two steps; in the first step, a primary fractional controller is designed from solving the H∞ mixed-sensitivity problem that uses fixed-integer weights. In the second step, the robustified fractional controller with adjustable fractional weights is designed in order to guarantee a good compromise between the nominal performance and the robust stability not only for the nominal plant, but also for all set of the neighbouring plants. The proposed robustified fractional controller is used to control the doubly fed induction generator. Its dynamic is modelled by the unstructured output-multiplicative uncertain plant. Simulation results given by both primary and robustified fractional controllers are compared in time and frequency domains with those given by the conventional integer H∞ controller in order to validate the effectiveness of the proposed method.
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Thèses sur le sujet "Robust stability (margins) and performance"

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Somers, Franca Maria Emma. « Nouveaux outils probabilistes pour améliorer la vérification et la validation des systèmes de contrôle spatiaux ». Electronic Thesis or Diss., Toulouse, ISAE, 2024. http://www.theses.fr/2024ESAE0054.

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Les activités actuelles de vérification et validation (V&V) dans l'industrie aérospatiale reposent principalement sur des outils de simulation qui prennent beaucoup de temps. Ces approches classiques de type Monte-Carlo sont largement utilisées depuis des décennies pour évaluer les performances des systèmes de guidage, de navigation et de contrôle (GNC) et des systèmes de contrôle d'attitude et d'orbite (SCAO) contenant de multiples paramètres incertains. Elles permettent de quantifier la probabilité d'occurrence de phénomènes suffisamment fréquents, mais peuvent échouer dans la détection de combinaisons rares, mais critiques, de paramètres. Au fur et à mesure que la complexité des systèmes spatiaux modernes augmente, cette limitation joue un rôle de plus en plus important. Ces dernières années, les méthodes d'analyse des pires cas basées sur des modèles ont atteint un bon niveau de maturité. Sans avoir recours à des simulations, ces outils peuvent explorer l'espace de toutes les combinaisons possibles de paramètres incertains et fournir des limites mathématiques garanties sur les marges de stabilité robustes et les niveaux de performance pire-cas. Les configurations problématiques, identifiées à l'aide de ces méthodes, peuvent être utilisées pour guider les campagnes Monte-Carlo finales, ce qui raccourcit considérablement le processus V&V standard. L'une des limites des méthodes classiques d'analyse pire-cas basées sur des modèles est qu'elles supposent que les paramètres incertains peuvent prendre n'importe quelle valeur dans un intervalle donné avec une probabilité égale. La probabilité d'occurrence d'une combinaison de paramètres pire-cas n'est donc pas mesurée et la conception d'un système peut ainsi être rejetée sur la base d'un scénario très rare et extrêmement improbable. Cette recherche se concentre sur μ-analyse probabiliste pour développer de nouveaux outils efficaces et fiables afin d'améliorer la caractérisation d'événements rares mais néanmoins possibles. Ceci permet de resserrer l'écart d'analyse V&V ci-dessus entre les méthodes basées sur la simulation et les approches pire-cas déterministes basées sur des modèles
Current verification and validation (V&V) activities in aerospace industry mostly rely on time-consuming simulation-based tools. These classical Monte Carlo approaches have been widely used for decades to assess performance of Guidance, Navigation and Control (GNC) algorithms and Attitude and Orbit Control Systems (AOCS) containing multiple uncertain parameters. They are able to quantify the probability of sufficiently frequent phenomena, but they may fail in detecting rare but critical combinations of parameters. As the complexity of modern space systems increases, this limitation plays an ever more important role. In recent years, model-based worst-case analysis methods have reached a good level of maturity. Without the need of simulations, these tools can fully explore the space of all possible combinations of uncertain parameters and provide guaranteed mathematical bounds on robust stability margins and worst-case performance levels. Problematic parameter configurations, identified using these methods, can be used to guide the final Monte Carlo campaigns, thereby drastically shortening the standard V&V process. A limitation of classical model-based worst-case analysis methods is that they assume the uncertain parameters can take any value within a given range with equal probability. The probability of occurrence of a worst-case parameter combination is thus not measured and a control architecture can be rejected based on a very rare and extremely unlikely scenario. This PhD research makes advances in probabilistic μ-analysis to develop new efficient and reliable tools to improve the characterization of rare but nonetheless possible events. This to tighten the aforementioned V&V analysis gap between simulation-based methods and deterministic model-based worst-case approaches
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Lin, Jong-Lick. « Control system design for robust stability and robust performance ». Thesis, University of Leicester, 1992. http://hdl.handle.net/2381/34797.

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A central problem in control system design is how to design a controller to guarantee that the closed-loop system is robustly stable and that performance requirements are satisfied despite the presence of model uncertainties and exogenous disturbance signals. The analysis problem, that is the assessment of control systems with respect to robust stability and robust performance, can be adequately solved using the structured singular value u as introduced by Doyle. The corresponding design problem (how to choose a controller K to minimize u) is still largely unsolved, but an approximate solution can be found using Doyle's D - K iteration. In this thesis we present an alternative algorithm, called u - K iteration, which works by flattening the structured singular value u over frequency. As a prelude to this a classical loop shaping approach to robust performance is presented for SISO systems, and is also based on flattening u. In u-synthesis it is often the case that real uncertainties are modelled as complex perturbations but the conservatism so introduced can be severe. On the other hand, if real uncertainties are modelled as real perturbations then D - K iteration is not relevant. It is shown that u - K iteration still works for real perturbations. In addition, a geometric approach for computing the structured singular value for a scalar problem with respect to real and/or complex uncertainty is described. This provides insight into the relationship between real u and complex u. A robust performance problem is considered for a 2-input 2-output high purity distillation column which is an ill-conditioned plant. Analysis reveals the potentially damaging effects on robustness of ill-conditioning. A design is carried out using u - K iteration and the "optimum" u compared with that obtained by Doyle and by Freudenberg for the same problem.
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Buchstaller, Dominic. « Robust stability and performance for multiple model switched adaptive control ». Thesis, University of Southampton, 2010. https://eprints.soton.ac.uk/72334/.

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While the concept of switching between multiple controllers to achieve a control objective is not new, the available analysis to date imposes various structural and analytical assumptions on the controlled plant. The analysis presented in this thesis, which is concerned with an Estimation-based Multiple Model Switched Adaptive Control (EMMSAC) algorithm originating from Fisher-Jeffes (2003), Vinnicombe (2004), is shown not to have such limitations. As the name suggests, the key difference between EMMSAC and common multiple model type switching schemes is that the switching decision is based on the outcome of an optimal estimation process. The use of such optimal estimators is the key that allows for a simplified, axiomatic approach to analysis. Also, since estimators may be implemented by standard optimisation techniques, their construction is feasible for a broad class of systems. The presented analysis is the first of its kind to provide comprehensive robustness and performance guarantees for a multiple model control algorithm, in terms of $l_p,\ 1\le p\le \infty$ bounds on the closed loop gain, and is applicable to the class of minimal MIMO LTI plants. A key feature of this bound is that it permits the on-line alteration of the plant model set (dynamic EMMSAC) in contrast to the usual assumption that the plant model set is constant (static EMMSAC). It is shown that a static EMMSAC algorithm is conservative whereas a dynamic EMMSAC algorithm, based on the technique of dynamically expanding the plant model set, can be universal. It is also shown that the established gain bounds are invariant to a refinement of the plant model set, e.g. as a successive increasing fidelity sampling of a continuum of plants. Dynamic refinement of the plant model set is considered with the view to increase expected performance. Furthermore, the established bounds --- which are also a measure of performance --- have the property that they are explicit in the free variables of the algorithm. It is shown that this property of the bound forms the basis for a principled, performance-orientated approach to design. Explicit, performance-orientated design examples are given and the trade off between dynamic and static constructions of plant model sets are investigated with respect to prior information on the acting disturbances and the uncertainty.
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Chellaboina, Vijaya-Sekhar. « Robust stability and performance for linear and nonlinear uncertain systems with structured uncertainty ». Diss., Georgia Institute of Technology, 1996. http://hdl.handle.net/1853/12903.

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Gade, Prasad V. N. « Performance Enhancement and Stability Robustness of Wing/Store Flutter Suppression System ». Diss., Virginia Tech, 1998. http://hdl.handle.net/10919/30339.

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In recent years, combat aircraft with external stores have experienced a decrease in their mission capabilities due to lack of robustness of the current passive wing/store flutter suppression system to both structured as well as unstructured uncertainties. The research program proposed here is to investigate the feasibility of using a piezoceramic wafer actuator for active control of store flutter with the goal of producing a robust feedback system that demonstrates increased performance as well as robustness to modeling errors. This approach treats the actuator as an active soft-decoupling tie between the wing and store, thus isolating the wing from store pitch inertia effects. Advanced control techniques are used to assess the nominal performance and robustness of wing/store system to flutter critical uncertainties. NOTE: (10/2009) An updated copy of this ETD was added after there were patron reports of problems with the file.
Ph. D.
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Emami, Tooran. « A bridge from stability to robust performance design of PID controllers in the frequency domain ». Diss., Wichita State University, 2009. http://hdl.handle.net/10057/2560.

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A graphical technique for finding proportional integral derivative (PID) controllers that stabilize a given single-input-single-output (SISO) linear time-invariant (LTI) system of any order system with time-delay has been solved. In this research, a method is introduced for finding all achievable PID controllers that also satisfy an H sensitivity, complementary sensitivity, weighted sensitivity, robust stability, or robust performance constraint. These problems can be solved by finding all PID controllers that simultaneously stabilize the closedloop characteristic polynomial and satisfy constraints defined by a set of related complex polynomials. There are several key advantages of this procedure. It does not require the plant transfer function model, but depends only on the frequency response. The ability to include the timedelay in the nominal model of the system will often allow for designs with reduced conservativeness in plant uncertainty and an increase in size of the set of all PID controllers that robustly stabilize the system and meet the performance requirements.
Thesis (Ph.D.)--Wichita State University, College of Engineering, Dept. of Electrical Engineering and Computer Science
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Mulay, Siddharth Pradeep. « Robustness Bounds For Uncertain Sampled Data Systems With Presence of Time Delays ». The Ohio State University, 2013. http://rave.ohiolink.edu/etdc/view?acc_num=osu1365971507.

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Belapurkar, Rohit K. « Stability and Performance of Propulsion Control Systems with Distributed Control Architectures and Failures ». The Ohio State University, 2013. http://rave.ohiolink.edu/etdc/view?acc_num=osu1357309068.

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Song, Zhuoyue. « Robust analysis and synthesis for uncertain negative-imaginary systems ». Thesis, University of Manchester, 2011. https://www.research.manchester.ac.uk/portal/en/theses/robust-analysis-and-synthesis-for-uncertain-negativeimaginary-systems(9de4af43-983c-42a2-bafe-062970a738be).html.

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Negative-imaginary systems are broadly speaking stable and square (equal number of inputs and outputs) systems whose Nyquist plot lies underneath (never touches for strictly negative-imaginary systems) the real axis when the frequency varies in the open interval 0 to ∞. This class of systems appear quite often in engineering applications, for example, in lightly damped flexible structures with collocated position sensors and force actuators, multi-link robots, DC machines, active filters, etc. In this thesis, robustness analysis and controller synthesis methods for uncertain negative-imaginary systems are explored. Two new reformulation techniques are proposed that facilitate both the robustness analysis and controller synthesis for uncertain negative-imaginary systems. These reformulations are based on the transformation from negative-imaginary systems to a bounded-real framework via the positive-real property. In the presence of strictly negative-imaginary uncertainty, the robust stabilization problem is posed in an equivalent H∞ control framework; similarly, a negative-imaginary robust performance analysis problem is cast into an equivalent μ-framework. The latter framework also allows robust stability analysis when the perturbations are a mixture of bounded-real and negative-imaginary uncertainties. The proposed two techniques pave the way for existing H∞ control and μ theory to be applied to robustness analysis and controller synthesis for negative-imaginary systems. In addition, a static state-feedback synthesis method is proposed to achieve robust stability of a system in the presence of strictly negative-imaginary uncertainties. The method is developed in the LMI framework, which can be solved efficiently using convex optimization techniques. The controller synthesis method is based on the negative-imaginary stability theorem: a positive feedback interconnection of two negative-imaginary systems is internally stable if and only if the DC loop gain is contractive and at least one of the systems in the interconnected loop is strictly negative-imaginary. Also, in order to handle non-strict negative-imaginary uncertainties, a strongly strictly negative-imaginary lemma is proposed that helps to ensure the strictly negative-imaginary property of the nominal closed-loop system for robustness. To this end, a state-space characterization for strictly negative-imaginary property is given for non-minimal systems where the conditions are convex and hence numerically attractive. The results in this thesis hence facilitate both the robustness analysis and controller synthesis for negative-imaginary systems that quite often arise in practical scenarios. In addition, they can be applied to quantify the worse-case performance for this class of systems. Therefore, the proposed results have important implications in controller synthesis for uncertain negative-imaginary systems that achieve not only robust stabilization but also robust performance.
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Ju, Hann Shing, et 朱漢興. « Robust Stability and Performance of Longitudinal Flight Controller Design ». Thesis, 1993. http://ndltd.ncl.edu.tw/handle/90494205959092599604.

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Livres sur le sujet "Robust stability (margins) and performance"

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Brenner, Marty. Wavelet filtering to reduce conservatism in aeroservoelastic robust stability margins. Edwards, Calif : National Aeronautics and Space Administration, Dryden Flight Research Center, 1998.

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Brenner, Marty. Wavelet filtering to reduce conservatism in aeroservoelastic robust stability margins. Edwards, Calif : National Aeronautics and Space Administration, Dryden Flight Research Center, 1998.

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Rick, Lind, et Dryden Flight Research Facility, dir. Wavelet filtering to reduce conservatism in aeroservoelastic robust stability margins. Edwards, Calif : National Aeronautics and Space Administration, Dryden Flight Research Center, 1998.

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Castellanos, Rafael B. Robust stability and performance analysis of large scale power systems with real parametric uncertainty : A structured singular value approach. Sous la direction de Messina Arturo R. New York : Nova Science Publishers, 2008.

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Rawson, Jenny Louise. Evaluation of stability margins and design of robust controllers for hybrid systems. 1990.

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Chapitres de livres sur le sujet "Robust stability (margins) and performance"

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Lind, Rick, et Marty Brenner. « Stability Margins ». Dans Robust Aeroservoelastic Stability Analysis, 99–109. London : Springer London, 1999. http://dx.doi.org/10.1007/978-1-4471-0849-8_8.

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Lind, Rick, et Marty Brenner. « Robust Stability Margins of a Pitch-Plunge System ». Dans Robust Aeroservoelastic Stability Analysis, 117–51. London : Springer London, 1999. http://dx.doi.org/10.1007/978-1-4471-0849-8_10.

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Gu, Da-Wei, Petko H. Petkov et Mihail M. Konstantinov. « Robust Stability and Performance ». Dans Robust Control Design with MATLAB®, 145–72. London : Springer London, 2013. http://dx.doi.org/10.1007/978-1-4471-4682-7_10.

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Lind, Rick, et Marty Brenner. « Robust Flutter Margins of the F/A-18 SRA ». Dans Robust Aeroservoelastic Stability Analysis, 153–71. London : Springer London, 1999. http://dx.doi.org/10.1007/978-1-4471-0849-8_11.

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Dong, Daoyi, et Ian R. Petersen. « Robust Stability and Performance Analysis of Quantum Systems ». Dans Learning and Robust Control in Quantum Technology, 177–218. Cham : Springer International Publishing, 2023. http://dx.doi.org/10.1007/978-3-031-20245-2_7.

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Yedavalli, Rama K. « Performance Robustness Analysis via Root Clustering (Robust D-Stability) ». Dans Robust Control of Uncertain Dynamic Systems, 75–100. New York, NY : Springer New York, 2013. http://dx.doi.org/10.1007/978-1-4614-9132-3_3.

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Mitov, Alexander, Tsonyo Slavov, Jordan Kralev et Ilcho Angelov. « Robust Stability and Performance Investigation of Electrohydraulic Steering Control System ». Dans Lecture Notes of the Institute for Computer Sciences, Social Informatics and Telecommunications Engineering, 386–400. Cham : Springer International Publishing, 2021. http://dx.doi.org/10.1007/978-3-030-78459-1_29.

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Botelho, Rui M., et Richard E. Christenson. « Robust Stability and Performance Analysis for Multi-actuator Real-Time Hybrid Substructuring ». Dans Dynamics of Coupled Structures, Volume 4, 1–7. Cham : Springer International Publishing, 2015. http://dx.doi.org/10.1007/978-3-319-15209-7_1.

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Fiorio, Giovanni, Mario Milanese et Antonio Vicino. « Robust Stability and Performance in the Presence of Parametric and Norm Bounded Uncertainty ». Dans Systems, Models and Feedback : Theory and Applications, 229–48. Boston, MA : Birkhäuser Boston, 1992. http://dx.doi.org/10.1007/978-1-4757-2204-8_17.

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Bonassi, Fabio. « Reconciling Deep Learning and Control Theory : Recurrent Neural Networks for Indirect Data-Driven Control ». Dans Special Topics in Information Technology, 77–87. Cham : Springer Nature Switzerland, 2024. http://dx.doi.org/10.1007/978-3-031-51500-2_7.

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AbstractThis Brief aims to discuss the potential of Recurrent Neural Networks (RNNs) for indirect data-driven control. Indeed, while RNNs have long been known to be universal approximators of dynamical systems, their adoption for system identification and control has been limited by the lack of solid theoretical foundations. We here intend to summarize a novel approach to address this gap, which is structured in two contributions. First, a framework for learning safe and robust RNN models is devised, relying on the Incremental Input-to-State Stability ($$\delta $$ δ ISS) notion. Then, after a $$\delta $$ δ ISS black-box model of the plant is identified, its use for the design of model-based control laws (such as Nonlinear MPC) with closed-loop performance guarantees is illustrated. Finally, the main open problems and future research directions are outlined.
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Actes de conférences sur le sujet "Robust stability (margins) and performance"

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Knapp, Marit, Christina Ivler, Marcos Berrios, Tom Berger et Mark Tischler. « Kalman Filter Estimation of Rotor-State Flapping : An Optimization-based Approach with UH-60 Flight Test Data ». Dans Vertical Flight Society 73rd Annual Forum & Technology Display, 1–16. The Vertical Flight Society, 2017. http://dx.doi.org/10.4050/f-0073-2017-12185.

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Flight testing of explicit rotor-state feedback (RSF) fly-by-wire control laws showed that measuring rotor tip-path-plane (TPP) flapping, via a laser measurement system, provided additional lead to the control system. This resulted in superior handling qualities in turbulence and heavy winds and improved stability margins. However, a significant impediment to the adoption of explicitly measured RSF has been the difficulty in extracting reliable rotor measurements. Therefore, this paper describes the development of a Kalman filter that was designed to estimate rotor TPP coordinates, and remove noise from the flapping signals while retaining the useful information without introducing large time delay, as would be the case for conventional low pass filtering. A new method for the design of the process noise covariance matrix using optimization of frequency domain specifications was implemented using flight test data from the UH-60 Black Hawk. The design was integrated into an explicit rotor-state feedback control algorithm, where it was tested for robustness to sensor faults and effectiveness based on improvements to stability margins. The results showed that the Kalman filter was robust to rotor blade sensor spike and drop-out faults and resulted in improved stability margins and handling qualities.
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Horn, Joseph, Dooyong Lee, Junfeng Yang et Chengjian He. « Parameter Optimization of Dynamic Inversion Control Laws for Shipboard Operations ». Dans Vertical Flight Society 73rd Annual Forum & Technology Display, 1–14. The Vertical Flight Society, 2017. http://dx.doi.org/10.4050/f-0073-2017-12070.

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Two approaches to gains optimization of dynamic inversion control laws have been developed to facilitate the shipboard operation of rotorcraft. The first approach is a frequency-based method to optimize the tradeoff between stability margins and disturbance rejection properties; the second approach uses direct optimization of gains to enhance tracking performance in the time domain. Comparative studies show that both methods tend to use high gain design for improvement of tracking error while rejecting airwake disturbances and following station-keeping commands over a moving deck. The frequency domain based method provides firm information on the margin to instability, although this is done via analysis of each axis independently. The direct optimization approach directly addresses tracking error performance in all axes, but the method resulted in only moderate improvements over the baseline gains for the particular case studied.
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Ivler, Christina, Kevin Kalinowski, Marit Knapp, M. Mansur et Zachariah Morford. « Flight Test of Explicit and Implicit Rotor-State Feedback Fly-By-Wire Control Laws ». Dans Vertical Flight Society 72nd Annual Forum & Technology Display, 1–22. The Vertical Flight Society, 2016. http://dx.doi.org/10.4050/f-0072-2016-11458.

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Rotor-state feedback (RSF) technology uses tip-path-plane measurements of the rotor to improve the tracking response of the aircraft in winds and turbulence, and provide improved stability margins. Three fly-by-wire control systems were designed and flight tested on the RASCAL JUH-60A aircraft to determine the benefits of RSF. A Baseline control system that used only conventional fuselage feedback but was optimized for Level 1 performance was compared to two control systems that used both rotor-state and fuselage feedback (and were also optimized for Level 1). The Implicit RSF control system implemented fuselage feedback and estimated (implicit) rotor-state feedback. The Explicit RSF control system implemented fuselage feedback and measured (explicit) rotor-state feedback via a laser measurement system installed on the aircraft. The sensor characteristics, frequency response validation, handling qualities ratings, and MTE tracking performance for hover/low-speed are discussed in this paper.
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Franca Somers, Miss, Clément Roos, Francesco Sanfedino, Samir Bennani et Valentin Preda. « Probabilistic stability margins and their application to AOCS validation ». Dans ESA 12th International Conference on Guidance Navigation and Control and 9th International Conference on Astrodynamics Tools and Techniques. ESA, 2023. http://dx.doi.org/10.5270/esa-gnc-icatt-2023-089.

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Current validation and verification (V&V) activities in aerospace industry mostly rely on time-consuming simulation-based tools. These tools can give a measure of probability for sufficiently frequent phenomena, but they may fail in detecting rare but critical combinations of parameters. As the complexity of modern space systems increases, this limitation plays an ever-increasing role. In recent years, model-based worst-case analysis methods have reached a good level of maturity. Without the need of simulations, these tools can fully explore the space of all possible combinations of uncertain parameters and provide guaranteed mathematical bounds on robust stability and worst-case performance levels. However, they give no measure of probability and can therefore be overly conservative. Introduced more recently probabilistic μ-analysis combines worst-case information with probability measure. As such, it tempts to bridge the analysis gap between Monte Carlo simulations and deterministic μ-analysis [4]. The STOchastic Worst-case Analysis Toolbox (STOWAT), is a toolbox dedicated to probabilistic μ-analysis, developed by ONERA, The French Aerospace Lab. The original version of the toolbox, released by [9] and [1], only allowed for probabilistic robust stability and H∞ performance analysis. However, for the STOWAT to be fully convincing for industry, it should be as efficient and versatile as possible. For this purpose, focus has been on efficiency improvement ever since [3]. Furthermore, the toolbox was recently equipped with four probabilistic stability margin algorithms, devoted to probabilistic gain, phase, disk and delay margin analysis [8], [2], [7]. All four can be classified as μ-analysis based Branch-and-Bound (B&B) algorithms. At each iteration sufficient μ-analysis based conditions are evaluated to ascertain if the considered margin is guaranteed to be below (violation test) or above (satisfaction test) a desired threshold on a given set of uncertainties. If no conclusions can be drawn, the uncertainty set is split into two subsets and the analysis is repeated on each of them. These tools are limited to Single-Input Single-Output (SISO) system analysis. But since most industrial problems involve Multiple-Input Multiple-Output (MIMO) systems, this contribution first focuses on extending the algorithms to MIMO system analysis. Only adjustments need to be made to the conditions used to determine whether the satisfaction test or violation test should be applied. For SISO systems these conditions mostly rely on grid-based methods. However, in [8] it was already shown that gridding is usually very efficient for SISO and loop-at-a-time margin analysis, but gets quickly slower as the number of input/output channels increases. An alternative approach for MIMO systems, using μ-based tools was already proposed for disk margin analysis in [8]. This approach is used again here for MIMO phase, gain and delay margin analysis. However, it should be noted that the μ-based algorithm used should be adapted to the type of uncertainties (real/complex) in the studied stability margin problem. The developed MIMO analysis algorithms are all implemented in the STOWAT. Besides MIMO analysis, there is also an increased interest in multivariable margin analysis. This is because most realistic systems are subject to multiple perturbations at the same time. Multivariable analysis can for instance be an alternative to disk margin analysis [6], [8] in the case of simultaneous analysis of gain and phase perturbations. A probabilistic multivariable margin analysis algorithm is proposed in this contribution and implemented in the STOWAT. It was developed to overcome the conservatism provided by the deterministic worst-case equivalent at the end of the distribution tail. The STOWAT implementation allows users to specify multiple desired stability margins and determine the probability of multivariable margin violation. Analysis can be performed for both SISO and MIMO systems, where for MIMO systems different margin requirements can be set for each input and/or output. The heart of the existing algorithms remains the same, but two main modifications are needed. First a few additional matrix operations to construct the perturbed system used by the B&B algorithm should be included. Then new μ-analysis based conditions involving multiple real and complex uncertainties should be defined to determine whether the satisfaction or violation test should be performed. To demonstrate the added value of the developed tools, they are applied to analyse two satellite models: an academic model and a realistic benchmark. The academic model represents the spinning satellite adapted from [10] and the realistic one concerns the satellite with two flexible solar panels, previously introduced in [5]. References [1] J.-M. Biannic, C. Roos, S. Bennani, F. Boquet, V. Preda, and B. Girouart, “Advanced probabilistic μ-analysis techniques for AOCS validation,” European Journal of Control, vol. 62, pp. 120–129, 2021. [2] F. Somers, C. Roos, F. Sanfedino, S. Bennani, and V. Preda, “Probabilistic delay margin analysis,” Submitted to the American Control Conference, 2023. [3] C. Roos, J.-M. Biannic, and H. Evain, “A new step towards the integration of probabilistic μ in the aerospace V&V process,” in Proceedings of the 6th CEAS Conference on Guidance, Navigation and Control, 2022. [4] C. Roos, F. Sanfedino, V. Preda, and S. Bennani, “Phd position in analysis of aerospace control systems: Enhanced probabilistic tools to improve verification and validation of space control systems,” 2021. [5] F. Sanfedino, D. Alazard, E. Kassarian, and F. Somers, “Satellite dynamics toolbox library: a tool to model multi body space systems for robust control synthesis and analysis,” Submitted to the IFAC World Congress, 2023. [6] P. Seiler, A. Packard, and P. Gahinet, “An introduction to disk margins [lecture notes],” IEEE Control Systems Magazine, vol. 40, no. 5, pp. 78–95, 2020. [7] F. Somers, C. Roos, F. Sanfedino, S. Bennani, and V. Preda, “Comparative study of new probabilistic delay margin analysis techniques,” Submitted to International Journal of Robust and Nonlinear Control, 2023. [8] F. Somers, S. Thai, C. Roos, J.-M. Biannic, S. Bennani, V. Preda, and F. Sanfedino, “Probabilistic gain, phase and disk margins with application to AOCS validation,” in Proceedings of the 10th IFAC Symposium on Robust Control Design, 2022. [9] S. Thai, C. Roos, and J.-M. Biannic, “Probabilistic μ-analysis for stability and H∞ performance verification,” in Proceedings of the American Control Conference, 2019. [10] K. Zhou, J. Doyle, and K. Glover, Robust and optimal control. Prentice-Hall, New Jersey, 1996.
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Kharisov, Evgeny. « Improving Stability Margins of Rotational Vibration Feed-Forward Compensator ». Dans ASME 2014 Conference on Information Storage and Processing Systems. American Society of Mechanical Engineers, 2014. http://dx.doi.org/10.1115/isps2014-6951.

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This work focuses on stability analysis and design for rotational vibration feed-forward (RVFF) compensator for hard disk drive (HDD) servo control system. We consider the effect of the coupling phenomenon between the voice coil motor (VCM) control current and the rotational vibration acceleration measurements. The coupling creates an undesirable feedback loop, which affects stability of the RVFF compensator as well as it limits the achievable system performance. In this work we present a method for the parasitic coupling mitigation. This method uses self-induced coupling vibration prediction to remove the coupling signal component from the rotational vibration (RV) acceleration measurements. We consider linear time invariant coupling estimator, which is more appealing for analysis in frequency domain, as well as its nonlinear adaptive version, which is more suitable for robust operation in uncertain environment.
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Halbe, Omkar, Milan Vrdoljak, Manfred Hajek et Tim Mehling. « Synthesis and Piloted Evaluation of Advanced Rotorcraft Response-Types Using Robust Sliding Mode Control ». Dans Vertical Flight Society 77th Annual Forum & Technology Display. The Vertical Flight Society, 2021. http://dx.doi.org/10.4050/f-0077-2021-16789.

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Sliding mode control (SMC) is a promising technique for robust control synthesis with desirable properties. This paper describes the synthesis and piloted evaluation of advanced helicopter response-types using the SMC technique. The required closed-loop response characteristics are specified as ideal, lower-order, axial transfer functions that conform to predicted level 1 handling qualities. Two-loop, full-authority, output-tracking SMC laws are then synthesized to enforce the closed-loop performance and accurately track pilot commands. Analytical proofs for SMC gain tuning are given for the closed-loop performance to remain robust to unknown but bounded uncertainties in the input channels and the effects of rotor modes on closed-loop stability. The closed-loop eigenstructure is nearly identical to the specified closed-loop performance and has good modal decoupling. Furthermore, a frequency domain analysis with a nonlinear helicopter model shows good stability margins and disturbance rejection characteristics. Finally, the paper reports on simulation testing conducted with four experimental test pilots in a rotorcraft simulation environment. The simulation results indicate improved mission task performance and handling qualities ratings, and a substantial reduction in pilot workload for the SMC-based advanced response-types compared to the bare-airframe responses.
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Pan, Jinwen, Omid Bagherieh, Behrooz Shahsavari et Roberto Horowitz. « Triple-Stage Track-Following Servo Design for Hard Disk Drives ». Dans ASME 2016 Dynamic Systems and Control Conference. American Society of Mechanical Engineers, 2016. http://dx.doi.org/10.1115/dscc2016-9770.

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This paper studies possible robust control design methods in triple-stage actuation settings for achieving minimum position error signal (PES) while maintaining enough stability margins. Firstly, the sensitivity-decoupling design technique, is utilized to estimate the resulting increase in low frequency disturbance attenuation and servo bandwidth. A systematic tuning methodology based on μ-synthesis is then proposed for track-following servo design of triple-stage actuation systems. In this approach, the objective is to minimize the PES, by considering all constraints and uncertainties explicitly in the design. We describe a step by step Multi-Input Single-Output (MISO) controller design methodology which includes system modeling, noise characterization, control objective determination and controller synthesis and verification. In this methodology, servo bandwidth is not the only performance metric. Rather, the control objective will be to minimize the closed-loop system H∞ norm directly, while all stroke and control constraints are satisfied and enough stability margin is ensured. The proposed method is applied to design track-following feedback controllers for single-, dual- and triple-stage actuation systems. Simulation results show that compared to dual-stage actuation, triple-stage actuation enhances low frequency disturbance rejection by 6 dB at around 100Hz and increases servo bandwidth from ∼3kHz to ∼5kHz.
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Griffin, D., et A. G. Kelkar. « LQG-Based Robustifying Flight Control System ». Dans ASME 2003 International Mechanical Engineering Congress and Exposition. ASMEDC, 2003. http://dx.doi.org/10.1115/imece2003-43596.

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This paper presents a robust controller design for an automatic flight control system (AFCS) for a fighter aircraft model with eight inputs and seven outputs. The controller is designed based on McFarlane-Glover robustifying technique using a simple baseline LQG design. Controllers designed purely based on traditional LQG techniques are known to have no guaranteed robustness margins. The McFarlane-Glover technique can be used to enhance the stability robustness of the baseline LQG design using a two-step design process. In the first step, an LQG controller is designed which is optimized only for performance without any consideration to robustness. In the second step, the performance optimized LQG design is rendered robust using McFarlane-Glover procedure. The robustifying procedure uses a coprime factor uncertainty model and H∞ optimization. An important advantage of this procedure is that no problem dependent uncertainty modelling or weight selection is required in the second step of the process. The robustifying procedure also yields the quantitative estimate of the robustness.
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So¨ffker, Dirk, Yan Liu, Zhiping Qiu, Fan Zhang et Peter C. Mu¨ller. « Robust Control of Uncertain Systems With Nonlinearities Using Model-Based Online Robustness Measure ». Dans ASME 2007 International Design Engineering Technical Conferences and Computers and Information in Engineering Conference. ASMEDC, 2007. http://dx.doi.org/10.1115/detc2007-34343.

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In this contribution, the dynamics of linear dynamical systems with nonlinearities or of nonlinear systems with structured uncertainties is controlled based on the stability analysis using the interval-analysis set-theoretic approach and combining the approach with online-optimization of the control parameters. For the online-analysis approach, a high-gain Proportional-Integral-Observer (PI-Observer) is used to estimate the model uncertainty. The estimation can be used as an online-measure of the actual model uncertainty bound which is assumed as known for the online interval analysis. Explicit expressions are given for computing the uncertain linear system stability margin in parameter space, which provides a measure of maximal parameter uncertainties preserving stability of uncertain system around known stable nominal system equilibrium. The robust PI-Observer model-based estimations are used as bounds to evaluate the system stability. The optimization of varied control gains can be used for the optimization of the introduced robustness measure, controlling uncertain nonlinear systems. The results show that the introduced new approach gives better results with respect to robustness and control performance than the classical nonlinear control method and the usual robust control method.
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Fadali, M. S., L. E. LaForge et A. Sonbol. « Linear time computation of robust stability margins ». Dans Proceedings of American Control Conference. IEEE, 2001. http://dx.doi.org/10.1109/acc.2001.946167.

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Rapports d'organisations sur le sujet "Robust stability (margins) and performance"

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Krause, James M., Pramod P. Khargonekar et Gunter Stein. Robust Adaptive Control : Stability and Asymptotic Performance. Fort Belvoir, VA : Defense Technical Information Center, février 1990. http://dx.doi.org/10.21236/ada219259.

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Balakrishnan, Venkataramanan. Robust Gain-Scheduled Nonlinear Control Design for Stability and Performance. Fort Belvoir, VA : Defense Technical Information Center, avril 2000. http://dx.doi.org/10.21236/ada377873.

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Yedavalli, Rama K. Robust Stability and Performance for Linear Systems with Structured and Unstructured Uncertainties. Fort Belvoir, VA : Defense Technical Information Center, juin 1990. http://dx.doi.org/10.21236/ada225697.

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Volpe Martincus, Christian, et Jerónimo Carballo. Is Export Promotion Effective in Developing Countries ? Firm-Level Evidence on the Intensive and Extensive Margins of Exports. Inter-American Development Bank, août 2010. http://dx.doi.org/10.18235/0011220.

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How effective are export promotion activities in developing countries? What are the channels through which export promotion affects firms' exports, the intensive margin or the extensive margin? Empirical evidence in this respect is scarce. We aim at filling this gap in the literature by providing evidence on the impact of export promotion on export performance using a unique firm-level dataset for Peru over the period 2001-2005. We find that export promotion actions are associated with increased exports, primarily along the extensive margin, both in terms of markets and products. This result is robust across alternative specifications and estimation methods.
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Trivelli, Carolina, Sergio Navajas, Mark D. Wenner et Alvaro Tarazona. Managing Credit Risk in Rural Financial Institutions in Latin America. Inter-American Development Bank, mai 2007. http://dx.doi.org/10.18235/0008848.

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The purpose of this report is to review common credit risk management techniques used in a sample of Latin American financial institutions with agricultural portfolios, identify the factors that contribute to successful credit risk management as measured by several key financial performance indicators in order to assist donors, governments, and owners of financial institutions to promote and adopt the most efficient and robust techniques. This report also examines a sample of 42 financial institutions in Latin America that have agricultural portfolios, and identifies their principal perceived risks, how they asses and manage credit risk, and how effective they are in the process as measured by key financial performance indicators (such as asset quality, portfolio growth, and profit margins).
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D’Agostino, Martin, Nigel Cook, Liam O’Connor, Annette Sansom, Dima Semaan, Anne Wood, Sue Keenan et Linda Scobie. Optimising extraction and RT-qPCR-based detection of hepatitis E virus (HEV) from pork meat and products. Food Standards Agency, juillet 2023. http://dx.doi.org/10.46756/sci.fsa.ylv958.

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Hepatitis E is an infection of the liver caused by the hepatitis E virus (HEV). HEV infection usually produces a mild disease, hepatitis E. However, disease symptoms can vary from no apparent symptoms to liver failure. There are 4 main types (genotypes) of the virus that cause concern in humans. Genotypes 1 and 2 infections are mainly restricted to humans but 3 and 4 can be identified in numerous other animal species including pigs. Transmission routes of HEV genotypes 3 and 4 have been identified to include the consumption of food products derived from infected animals and shellfish, and via transfusion of infected blood products. Hepatitis E infection is still an emerging issue in the UK and there is evidence to suggest an association of this virus with undercooked pork and pork products. Currently, there is no standardized method for evaluating the stability of HEV that may be present in food during cooking processes. There is also lack of a suitable method that can detect only infectious HEV. The proposed project aimed to address a key gap in resources for methodology related to the detection of HEV in pork and pork products. Currently the lack of a standardised method for the detection of HEV has resulted in individual laboratories either utilising their own methods or adapting methods from previously published work. This leads to a high degree of variability between the interpretation of results and does nothing to progress or provide benefit to the food industry. By interrogating the existing published methods, the project sought to refine and optimise elements of existing protocols in order to enhance the performance characteristics of the method and to simplify the methodology wherever possible. The aim was to produce a validated method which is both robust and repeatable which can be easily integrated into food laboratories capable of performing virus related work. Overall, the final method chosen was devoid of hazardous reagents and utilised easily accessible equipment. To verify the robustness of the method, an international collaborative trial was performed, with 4 UK and 3 European participant laboratories. The participating laboratories conducted analyses of pork liver samples artificially contaminated with various levels of HEV (including uncontaminated samples). The trial showed that the HEV DETECT method was just as reproducible between laboratories as it was repeatable within a laboratory. It is envisaged that the developed system will be put forward as a suitable candidate for ISO certification as a standard method. The establishment of these methods in UK laboratories could result in the availability of independent testing services for both domestic and imported pork /pork-based products. The availability of this method is in essence innovation. This work is essential to industry to help support further research to ensure that public health safety and confidence in pork and other “HEV risk” food products is maintained and improved.
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Event-Triggered Adaptive Robust Control for Lateral Stability of Steer-by-Wire Vehicles with Abrupt Nonlinear Faults. SAE International, juillet 2022. http://dx.doi.org/10.4271/2022-01-5056.

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Because autonomous vehicles (AVs) equipped with active front steering have the features of time varying, uncertainties, high rate of fault, and high burden on the in-vehicle networks, this article studies the adaptive robust control problem for improving lateral stability in steer-by-wire (SBW) vehicles in the presence of abrupt nonlinear faults. First, an upper-level robust H∞ controller is designed to obtain the desired front-wheel steering angle for driving both the yaw rate and the sideslip angle to reach their correct values. Takagi-Sugeno (T-S) fuzzy modeling method, which has shown the extraordinary ability in coping with the issue of nonlinear, is applied to deal with the challenge of the changing longitudinal velocity. The output of the upper controller can be calculated by a parallel distributed compensation (PDC) scheme. Then an event-triggered adaptive fault-tolerant lower controller (ET-AFTC) is proposed to drive the whole SBW system driving the desired steering angle offered by the upper controller with fewer communication resources and strong robustness. By employing a backstepping technique, the tracking performance is improved. The dynamic surface control (DSC) approach is used to avoid the problem of repeated differentiations, and Nussbaum function is adopted to overcome the difficulty of unknown nonlinear control gain. Both the stability of the upper and lower controllers can be guaranteed by Lyapunov functions. Finally, the simulations of Matlab/Simulink are given to show that the proposed control strategy is effectively able to deal with the abrupt nonlinear fault via less communication resources and perform better in ensuring the yaw stability of the vehicle.
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