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Author

Changzhu Zhang

Other affiliations: City University of Hong Kong
Bio: Changzhu Zhang is an academic researcher from Tongji University. The author has contributed to research in topics: Control theory & Fuzzy control system. The author has an hindex of 13, co-authored 37 publications receiving 570 citations. Previous affiliations of Changzhu Zhang include City University of Hong Kong.

Papers
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Journal ArticleDOI
TL;DR: The problem of steering control is investigated for vehicle path tracking in the presence of parametric uncertainties and nonlinearities, and the effectiveness of the proposed fuzzy observer-based output feedback controller is demonstrated in Carsim/Matlab joint simulation environment.
Abstract: In this paper, the problem of steering control is investigated for vehicle path tracking in the presence of parametric uncertainties and nonlinearities In practice, the vehicle mass varies due to the number of passengers or amount of payload, while the vehicle velocity also changes during normal cruising, which significantly influences vehicle dynamics Moreover, the vehicle dynamics are strongly nonlinear caused by the tire/road forces under different road surface conditions With fuzzy modeling method, the original nonlinear path tracking system with parameter variations is first formulated as a T–S fuzzy model with additive norm-bounded uncertainties, and then an approach to the fuzzy observer-based output feedback steering control for vehicle dynamics is proposed under a fuzzy Lyapunov function framework By employing matrix inequality convexifying techniques, a sufficient condition is developed in the form of linear matrix inequalities such that the closed-loop path tracking error system is asymptotically stable with a guaranteed $\mathcal {H}_{\infty }$ level Finally, the effectiveness of the proposed fuzzy observer-based output feedback controller is demonstrated in Carsim/Matlab joint simulation environment, via which the advantage of a T–S fuzzy observer-based output controller over the closed-loop driver model embedded in Carsim is also shown with parametric uncertainties and nonlinearities

120 citations

Journal ArticleDOI
TL;DR: This paper investigates the problem of H∞ filtering for a class of nonlinear discrete-time systems with measurement quantization and packet dropouts with a piecewise-Lyapunov function and proposes an approach to the design of H ∞-piecewise filter such that the filtering-error system is stochastically stable with a guaranteed H⩽ performance.
Abstract: This paper investigates the problem of H∞ filtering for a class of nonlinear discrete-time systems with measurement quantization and packet dropouts. Each output is transmitted via an independent communication channel, and the phenomenon of packet dropouts in transmission is governed by an individual random binary distribution, while the quantization errors are treated as sector-bound uncertainties. Based on a piecewise-Lyapunov function, an approach to the design of H∞-piecewise filter is pro posed such that the filtering-error system is stochastically stable with a guaranteed H∞ performance. Some slack matrices are introduced to facilitate the filter design procedure by eliminating the coupling between the Lyapunov matrices and the system matrices. The filter parameters can be obtained by solving a set of linear matrix inequalities (LMIs), which are numerically tractable with commercially available software. Finally, two illustrative examples are provided to show the effectiveness of the proposed method.

102 citations

Journal ArticleDOI
TL;DR: A novel observer-based piecewise fuzzy filter design is developed for the filtering error system concerned to be asymptotically stable with a given disturbance attenuation level and reduced transmission rate.
Abstract: This paper is concerned with the design of ${\mathcal {H}_{\infty }}$ event-triggered filter for a class of Takagi–Sugeno fuzzy systems. Based on the proposed communication strategy, only the measured outputs of the physical plant that violate a predefined triggering condition will win the right for transmission in the shared communication channel. Considering that the implementation of the filter may not be synchronized with the plant trajectories due to the asynchronous premise variables in network environment, a novel observer-based piecewise fuzzy filter is proposed. By adopting the idea of input delay method, the filtering error dynamics is reformulated as a new event-triggered piecewise fuzzy system. By applying a piecewise Lyapunov–Krasovskii functional and some techniques on matrix convexification, a method of event-triggered ${\mathcal {H}_{\infty }}$ piecewise filter design is developed for the filtering error system concerned to be asymptotically stable with a given disturbance attenuation level and reduced transmission rate. Moreover, a co-design algorithm to derive the filter gains and the event triggering parameters is proposed. Illustrative examples are finally given to show the effectiveness of the developed method.

84 citations

Journal ArticleDOI
TL;DR: This paper investigates the controller design for a class of linear network-based systems with communication constraints on both uplink and downlink channels, where the network-induced transmission time delay, packet dropouts, and signal quantization are considered simultaneously.
Abstract: This paper investigates the controller design for a class of linear network-based systems with communication constraints on both uplink and downlink channels, where the network-induced transmission time delay, packet dropouts, and signal quantization are considered simultaneously. To deal with the phenomenon of quantization, a novel approach is adopted, which converts the quantized state and control signal into a kind of actuator saturation with bounded disturbances. Based on a proposed Lyapunov-Krasovskii functional, the existence conditions of a linear memory-less state feedback controller are derived, and an estimation method for the domain of admissible initial conditions is proposed from which all solutions of the systems under study converge exponentially to an ellipsoid with a prescribed convergence rate. Finally, a simulation example is provided to show the effectiveness of the developed approach.

67 citations

Journal ArticleDOI
TL;DR: This article presents a nonmodel-based controller design for vehicle dynamic systems to improve lateral stability, where output tracking control and adaptive dynamic programming approaches are employed to track the desired yaw rate and, at the same time, mitigate the sideslip angle, roll angle, and roll rate of the vehicle.
Abstract: This article presents a nonmodel-based controller design for vehicle dynamic systems to improve lateral stability, where output tracking control and adaptive dynamic programming approaches are employed to track the desired yaw rate and, at the same time, mitigate the sideslip angle, roll angle, and roll rate of the vehicle. Moreover, different from some existing optimization methods in control allocation, the proposed control strategies, which distribute tire forces by learning, are only using the information of states, input, and reference signal instead of the knowledge of the vehicle system. The iterative process repeatedly uses the information about state and input to calculate the feedback gain. It can significantly reduce the learning time and computational burden. The effectiveness of the proposed controller design method is shown by CarSim simulations.

59 citations


Cited by
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01 Jan 2005
TL;DR: In this paper, a number of quantized feedback design problems for linear systems were studied and the authors showed that the classical sector bound approach is non-conservative for studying these design problems.
Abstract: This paper studies a number of quantized feedback design problems for linear systems. We consider the case where quantizers are static (memoryless). The common aim of these design problems is to stabilize the given system or to achieve certain performance with the coarsest quantization density. Our main discovery is that the classical sector bound approach is nonconservative for studying these design problems. Consequently, we are able to convert many quantized feedback design problems to well-known robust control problems with sector bound uncertainties. In particular, we derive the coarsest quantization densities for stabilization for multiple-input-multiple-output systems in both state feedback and output feedback cases; and we also derive conditions for quantized feedback control for quadratic cost and H/sub /spl infin// performances.

1,292 citations

Journal ArticleDOI
TL;DR: Two novel observer-based event-triggered control schemes, one centralized and the other distributed, are developed and it is shown that under the proposed control protocols, consensus can be reached if the underlying communication graph of the MAS is connected.
Abstract: This paper studies the consensus problem of linear multi-agent systems via observer-based event-triggered control. Two novel observer-based event-triggered control schemes, one centralized and the other distributed, are developed. It is shown that under the proposed control protocols, consensus can be reached if the underlying communication graph of the MAS is connected. An example is finally presented to illustrate the effectiveness of the proposed control methods.

467 citations

Journal ArticleDOI
TL;DR: It is proven that by designing the formation protocol using the proposed algorithm, time-varying formation can be achieved by multi-agent systems with general linear dynamics and switching directed topologies if the dwell time is larger than a positive threshold.

369 citations

Journal ArticleDOI
TL;DR: This paper attempts to present an overview of recent advances and unify them in a framework of network-induced issues such as signal sampling, data quantization, communication delay, packet dropouts, medium access constraints, channel fading and power constraint, and present respective solution approaches to each of these issues.
Abstract: A networked control system (NCS) is a control system which involves a communication network. In NCSs, the continuous-time measurement is usually sampled and quantized before transmission. Then, the measurement is transmitted to the remote controller via the communication channel, during which the signal may be delayed, lost or even sometimes not allowed for transmission due to the communication or energy constraints. In recent years, the modeling, analysis and synthesis of networked control systems (NCSs) have received great attention, which leads to a large number of publications. This paper attempts to present an overview of recent advances and unify them in a framework of network-induced issues such as signal sampling, data quantization, communication delay, packet dropouts, medium access constraints, channel fading and power constraint, and present respective solution approaches to each of these issues. We draw some conclusions and highlight future research directions in end.

329 citations

Journal ArticleDOI
TL;DR: This paper focuses on analyzing a new model transformation of discrete-time Takagi-Sugeno (T-S) fuzzy systems with time-varying delays and applying it to dynamic output feedback (DOF) controller design.
Abstract: This paper focuses on analyzing a new model transformation of discrete-time Takagi-Sugeno (T-S) fuzzy systems with time-varying delays and applying it to dynamic output feedback (DOF) controller design. A new comparison model is proposed by employing a new approximation for time-varying delay state, and then, a delay partitioning method is used to analyze the scaled small gain of this comparison model. A sufficient condition on discrete-time T-S fuzzy systems with time-varying delays, which guarantees the corresponding closed-loop system to be asymptotically stable and has an induced l2 disturbance attenuation performance, is derived by employing the scaled small-gain theorem. Then, the solvability condition for the induced l2 DOF control is also established, by which the DOF controller can be solved as linear matrix inequality optimization problems. Finally, examples are provided to illustrate the effectiveness of the proposed approaches.

326 citations