1,256 publications from this institution
This paper deals with the problem of observer-based controller design for a class of nonlinear systems subject to unknown inputs. A novel method is presented to design a controller using estimated state variables which guarantees all the state variables of the closed-loop system converge to the vicinity of the origin and stay there forever. This is done via satisfying several sufficient conditions in terms of nonlinear matrix inequalities. In light of linear algebra, particularly matrix decompositions, the achieved conditions will be converted to a Linear Matrix Inequality (LMI) problem to facilitate the procedure of computing the observer and controller gains. Finally, the effectiveness of the proposed method is illustrated by implementing on a highly nonlinear chaotic system.
In this paper mathematical modeling of a vehicle crash test based on a single-mass is studied. The model under consideration consists of a single-mass coupled with a spring and/or a damper. The parameters for the spring and damper are obtained by analyzing the measured acceleration in the center of gravity of the vehicle during a crash. A model with a nonlinear spring and damper is also proposed and the parameters will be optimized with different damper and spring characteristics and optimization algorithms. The optimization algorithms used are interior-point and firefly algorithm. The objective of this paper is to compare different methods used to establish a simple model of a car crash and validate the results against real crash data.
This paper addresses two control schemes for stochastic nonlinear systems. Firstly, an adaptive controller is designed for a class of motion equations. Then, a robust finite-time control scheme is proposed to stabilize a class of nonlinear stochastic systems. The stability of the closed-loop systems is established based on stochastic Lyapunov stability theorems. Links between these two methods are given. The efficiency of the control schemes is evaluated using numerical simulations.
Pinterest, a prominent social media platform and facilitator of social networks within virtual spaces, provides individuals the ability to access an array of resources. Teachers may seek out and share instructional resources and professional support to one another across subjects and content. However, in an era of big data metrics, researchers must find meaningful approaches to characterize resources accessed and shared. Resources may represent teachers’ sense-making of content and/or be part of students’ curriculum within the classroom. This study investigates how we can leverage computational science through machine learning to characterize the rigor of educational resources teachers curate, using a revised Bloom’s taxonomy, at scale within Pinterest. Practically, characterizing the nature of resources shared could support teachers and educational leaders as they seek to improve the quality of instructional tasks within schools.
This paper is concerned with event-based H <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">∞</sub> control for a class of networked Markov jump systems (MJSs) with missing measurements. The phenomenon of asynchronism occurs in both the controller and the actuator-failure model, which is estimated by the hidden Markov model, is taken into consideration. In addition, to reduce the burden of data transmission, a mode-dependent event-triggered mechanism (ETM) is proposed. Together with ETM, a network-induced delay is introduced. Subsequently, to guarantee that the MJS is stochastically stable, an event-based asynchronous controller is designed. Finally, to reveal the effectiveness of the proposed method, a simulation example of pulse width-modulation-driven boost converter is considered.
In this paper, the problem of stability analysis and control synthesis for Markovian jump linear systems with time delays and norm-bounded uncertainties is studied. The model under consideration consists of different time-invariant discrete, neutral and distributed delays. Delay-dependent sufficient conditions for the design of a mode-dependent delayed state feedback H <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">∞</sub> control are given in terms of linear matrix inequalities (LMIs). A controller which guarantees stochastic stability and a prescribed level of H <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">∞</sub> performance for the closed-loop system is then developed. A Lyapunov-Krasovskii functional (LKF) method underlies the control design. A numerical example with simulation results illustrates the effectiveness of the methodology.
No abstract is provided for this article.
No abstract is provided for this article.
This paper is concerned with the distributed H <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">∞</sub> filtering problem of discrete-time switched linear systems in sensor networks in face of packet dropouts and quantization. Specifically, due to the packet dropout phenomenon, the filters may lose access to the real-time switching signal of the plant. It is assumed that the maximal packet dropout number of switching signal is bounded. Then, a distributed filtering system is proposed by further considering the quantization effect. Based on the Lyapunov stability theory, a sufficient condition is obtained for the convergence of filtering error dynamics. The filter gain design is transformed into a convex optimization problem. In this paper, a quantitative relation between the switching rule missing rate and filtering performance is established. Furthermore, the upper bound of the switching rule missing rate is also calculated. Finally, the effectiveness of the proposed filter design is validated by a simulation study on the pulse-width-modulation-driven boost converter circuit. The impact of noise covariance, system dynamics, and network connectivity is studied, and some discussions are presented on how these parameters affect the filtering performance.
This chapter addresses the problem of leader-following exponential consensus in fractional-order descriptor nonlinear multi-agent systems through the design of an event-triggered sliding mode control strategy. Exponential consensus is achieved by defining an appropriate sliding surface and a controller, ensuring Mittag-Leffler stability for fractional-order systems. Due to the inherent memory property of the fractional-order calculus operator, a novel condition is established to prevent the occurrence of Zeno behavior, distinguishing this approach from existing event-triggered schemes. This new condition is crucial for maintaining practical implementability and system reliability. To demonstrate the effectiveness and feasibility of the proposed method, two illustrative examples are provided, showcasing the robustness and applicability of the strategy in achieving desired consensus among agents. These examples highlight the practical implications and advantages of the developed control approach in handling complex dynamics in multi-agent systems.
Maneuvering target tracking is a challenge. Target’s sudden speed or direction changing would make the common filtering tracker divergence. To improve the accuracy of maneuvering target tracking, we propose a tracking algorithm based on spline fitting. Curve fitting, based on historical point trace, reflects the mobility information. The innovation of this paper is assuming that there is no dynamic motion model, and prediction is only based on the curve fitting over the measured data. Monte Carlo simulation results show that, when sea targets are maneuvering, the proposed algorithm has better accuracy than the conventional Kalman filter algorithm and the interactive multiple model filtering algorithm, maintaining simple structure and small amount of storage.
This paper addresses the <svg style="vertical-align:-3.3907pt;width:29.8375px;" id="M1" height="16.025" version="1.1" viewBox="0 0 29.8375 16.025" width="29.8375" xmlns:xlink="http://www.w3.org/1999/xlink" xmlns="http://www.w3.org/2000/svg"> <g transform="matrix(.017,-0,0,-.017,.062,11.737)"><path id="x210B" d="M702 678l12 -14l-18 -14q-124 -96 -232 -310q25 10 62 21l53 18l33 43q101 126 187 195q88 70 135 70q57 0 57 -50q0 -78 -98 -145q-86 -58 -206 -105q-174 -251 -174 -334q0 -15 9.5 -25t24.5 -10q55 0 167 129l21 -13q-120 -146 -202 -146q-39 0 -63 24t-24 65
q0 101 104 262l-107 -41q-56 -110 -132 -193q-75 -82 -145 -109q-31 -11 -56 -11t-41 16.5t-16 43.5q0 129 283 247q17 29 20 33l22 36q1 2 9 13.5l14 20.5q18 28 59 77q34 39 87 86q-5 -1 -20 -1q-44 0 -124 44q-62 34 -102 34q-48 0 -82 -31q-34 -30 -34 -70q0 -44 22 -69
t66 -25q37 0 65 20.5t56 65.5l18 -9q-54 -107 -141 -107q-59 0 -93 34.5t-34 91.5q0 58 50 105q49 46 125 46q28 0 58 -11q35 -13 84 -38q59 -31 86 -31q42 0 80 19q16 9 42 28zM958 635q0 22 -24 22q-28 0 -86 -63q-56 -60 -128 -160q238 105 238 201zM307 241
q-110 -50 -165.5 -98t-55.5 -99q0 -24 24 -29q67 0 197 226z" /></g> <g transform="matrix(.012,-0,0,-.012,17.012,15.825)"><path id="x221E" d="M983 225q0 -112 -67 -174.5t-150 -62.5q-91 0 -154.5 43.5t-113.5 129.5q-49 -85 -104 -129t-138 -44q-98 0 -158.5 66t-60.5 154q0 59 21 106.5t54.5 75.5t70.5 43t73 15q90 0 152.5 -43.5t112.5 -128.5q48 84 104.5 128t140.5 44q93 0 155 -65t62 -158zM478 196
q-27 49 -47 80t-50 67t-64 54t-73 18q-48 0 -81.5 -47t-33.5 -128q0 -96 37.5 -157.5t99.5 -61.5q68 0 117.5 47t94.5 128zM889 204q0 91 -35.5 151t-99.5 60q-68 0 -119 -47t-95 -127q27 -49 47 -80.5t50 -67.5t65 -54t74 -18q113 0 113 183z" /></g> </svg> filtering problem for discrete fuzzy stochastic systems with time-varying delay and sensor saturation. Random noise depending on state and external disturbance is also taken into account. A decomposition approach is employed to solve the characteristic of sensor saturation. The scaled small gain (SSG) theorem is extended to the stochastic systems, which is employed to handle with the time-varying delay by transforming the original system into the form of an interconnected system consisting of two subsystems. By the proposed Lyapunov-Krasovskii function, the scaled small gains of the subsystems are analyzed, respectively. Sufficient conditions for the stochastic stability of the filtering error system with a prescribed <svg style="vertical-align:-3.3907pt;width:29.8375px;" id="M2" height="16.025" version="1.1" viewBox="0 0 29.8375 16.025" width="29.8375" xmlns:xlink="http://www.w3.org/1999/xlink" xmlns="http://www.w3.org/2000/svg"> <g transform="matrix(.017,-0,0,-.017,.062,11.737)"><use xlink:href="#x210B"/></g> <g transform="matrix(.012,-0,0,-.012,17.012,15.825)"><use xlink:href="#x221E"/></g> </svg> level are established such that the gains of the <svg style="vertical-align:-3.3907pt;width:29.8375px;" id="M3" height="16.025" version="1.1" viewBox="0 0 29.8375 16.025" width="29.8375" xmlns:xlink="http://www.w3.org/1999/xlink" xmlns="http://www.w3.org/2000/svg"> <g transform="matrix(.017,-0,0,-.017,.062,11.737)"><use xlink:href="#x210B"/></g> <g transform="matrix(.012,-0,0,-.012,17.012,15.825)"><use xlink:href="#x221E"/></g> </svg> filter can be obtained explicitly. Finally, simulation results are presented to demonstrate the effectiveness of the proposed approach.
This paper is concerned with the problem of robust stabilization for a class of uncertain two-dimensional (2D) discrete switched systems with state delays under asynchronous switching. The asynchronous switching here means that the switching instants of the controller experience delays with respect to those of the system. The parameter uncertainties are assumed to be norm-bounded. A state feedback controller is proposed to guarantee the exponential stability. The dwell time approach is utilized for the stability analysis and controller design. A numerical example is given to illustrate the effectiveness of the proposed method.
No abstract is provided for this article.
This chapter introduces the structural control concept for load reduction of OWTs. Theories for both passive and active structural control are introduced. Particularly, a spar-type FOWT is used as the study case to demonstrate the load mitigation effectiveness of the proposed structural control methods. For the passive case, design optimization process is performed on a TMD installed in the spar platform, and the obtained numerical simulation results have indicated the both their effectiveness and limits regarding different system parameters and installations. Regarding the active case, a gain scheduling H2/H∞ active structural full-state feedback controller is designed for an HMD installed at the tower top of a spar-type FOWT, aiming at both reducing tower bottom load and mitigating the aerodynamic disturbance. The results demonstrate that more load reduction could be achieved at the expense of more energy consumption. At the same time, this will bring the risk of instability. Moreover, the full-state feedback controller is not very practical from a technical point of view due to the lack of sensors and measurement inaccuracy.
This paper is focused on the event-triggered fuzzy sliding-mode control of networked control systems regulated by semi-Markov process. First, through movement-decomposition method, the networked control system is transformed into two lower-order subsystems. Then, an event-triggered scheme based on a delay system model approach is proposed in designing the switching surface and obtaining the sliding mode dynamics. Furthermore, a fuzzy sliding-mode controller is developed to realize reachability of a predefined switching surface and desirable sliding motion. Moreover, in terms of linear matrix inequality method, sufficient conditions for stochastic stability of the obtained sliding mode dynamics is developed in the sense of generally uncertain transition rates. Finally, the applicability of the proposed results are verified numerically on the single-link robot arm system.
In vibration control of adjacent buildings under seismic excitations, a twofold objective has to be considered:(i) to mitigate the vibrational response of the individual structures and (ii) to provide a suitable protection against interbuilding impacts (pounding). An interesting strategy to deal with this complex control problem consists in considering an integrated control system, which combines interbuilding actuation devices with local control systems implemented in the individual buildings. In this paper, an effective computational strategy to design this kind of integrated control systems is presented. The proposed design methodology is based on a linear matrix inequality formulation, allows including active and passive actuation devices, and makes it possible to deal with important information constraints associated to the problem. The main ideas are illustrated by means of a two-building system equipped with three actuation devices: two interstory actuation devices implemented at the ground level of the buildings, plus an interbuilding actuation device installed at the top level of the lowest building. For this control setup, two different integrated controllers are designed. A proper set of numerical simulations is conducted to assess the performance of the proposed controllers with positive results.
