Publications

In order to improve data query speed, there are four methods: optimization of SQL (Structured Query Language) statements and reasonable use of index, temporary tables and views are researched. Practice demonstrates these four methods can improve query speed and database performance.

This paper is concerned with bipartite consensus tracking for multi-agent systems with unknown disturbances. A barrier function-based adaptive sliding-mode control (SMC) approach is proposed such that the bipartite steady-state error is converged to a predefined region of zero in finite time. Specifically, based on an error auxiliary taking neighboring antagonistic interactions into account, an SMC law is designed with an adaptive gain. The gain can switch to a positive semi-definite barrier function to ensure that the error auxiliary is constrained to a predefined neighborhood of zero, which in turn guarantees practical bipartite consensus tracking. A distinguished feature of the proposed controller is its independence on the bound of disturbances, while the input chattering phenomenon is alleviated. Finally, a numerical example is provided to verify the effectiveness of the proposed controller.

This paper is concerned with distributed event-triggered H <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">∞</sub> filtering for a discrete-time linear system over a sensor network. Sensor nodes are physically distributed and communicated through network medium. Firstly, a distributed event-triggered communication scheme is presented to determine when the measurement output on each sensor node should be broadcast and transmitted to its neighboring nodes. Each sensor node is equipped with an event monitor which consists of an event generator and a store. The event generator is configured to produce a series of events according to an event triggering rule. The store is employed to reserve the latest data packets. Secondly, based on the Lyapunov functional approach, criteria for analyzing H <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">∞</sub> filtering performance and designing desired distributed event-triggered H <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">∞</sub> filters are derived such that the resultant filtering error system is asymptotically stable with a prescribed H <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">∞</sub> performance index. The filter design problem is posed in terms of linear matrix inequalities. Finally, an illustrative example is given to demonstrate the effectiveness of the obtained theoretical results.

This article investigates the network-based multiple operating points cooperative dynamic positioning of multiple unmanned surface vehicles. First, a dynamic positioning system model is established for multiple unmanned surface vehicles. Second, a network-based multiple operating points cooperative dynamic positioning control protocol and a resultant system model for multiple unmanned surface vehicles are constructed under fixed topologies. Third, a networked multiple operating points cooperative dynamic positioning control scheme, which can guarantee the multiple operating points cooperative dynamic positioning error exponentially converge to a bounded region, is proposed. The dynamic positioning control scheme design is then extended to the case of switching topologies. Finally, the multiple operating points cooperative dynamic positioning performance analysis verifies the efficiency of the proposed control schemes.

This paper is concerned with stability and passivity of negative feedback interconnection of two passive mechanical systems, communicated through communication networks. To model networked negative feedback interconnected mechanical systems, an appropriate network scheduling method based on event-triggered scheme is presented. With this event-triggered scheduling method, the communication bandwidth utilization is considerably reduced while preserving passivity of the interconnected mechanical systems. By constructing a novel discontinuous Lyapunov-Krasovskii functional, a sufficient condition for the networked feedback interconnected mechanical system to be asymptotically stable is derived, where network-induced delays are considered. A new sufficient condition to make the negative feedback interconnected mechanical system in network environments remain passive is correspondingly developed. A numerical example is provided to demonstrate the effectiveness of the proposed method.

This article is concerned with quasi-synchronization of grid-connected systems in electrical networks, where heterogeneous Inductance-Capacitance (LC) oscillators are coupled via electrical inductance subject to time-varying delays. Note that complete synchronization fails to be accomplished due to the existence of nonidentical parameters and quasi-synchronization cannot be achieved via non-delayed inductive coupling. A configuration of multiple heterogeneous LC oscillators with inductive coupling subject to time-varying lumped delay is first constructed by introducing an active delay intentionally. Then the complete-type Lyapunov-Krasovskii functionals (LKF) are constructed to investigate the exponential convergence of quasi-synchronization of LC oscillators in the presence of parameter mismatches utilizing the positive effects of interval time-varying delays. Some feasible synchronization criteria are derived. The gain matrix can be designed by solving a set of linear matrix inequalities combining an optimization algorithm. Finally, a numerical example of five LC oscillators in photovoltaic grid-connected system is given to demonstrate the effectiveness of the proposed method.

The technology of object persistence is first introduced. And then an designing scheme of information system is put forward, in which the object persistence layer is based on Hibernate; Finally, the scheme is implemented by Myeclispse development environment. The experiment result demonstrates the scheme simplifies data access processing, improves the readability, maintainability of code and efficiency of programming.

IP-based network delays in networked control systems (NCSs) are inherently nonuniformly distributed and behave with multifractal nature. This chapter proposes a delay distribution-based stability analysis and synthesis approach for a linear system controlled over an...

This paper is concerned with controller design for a class of nonlinear networked control systems. These systems are approximated by uncertain linear networked Takagi-Sugeno (T-S) models with both network-induced delay and data packet dropout. Sufficient conditions are derived for the existence of a fuzzy controllers. Then, an iterative algorithm for the controller design is proposed. A control problem of a flexible-joint robot arm system is studied to show the effectiveness of the iterative algorithm.

This paper is concerned with the recursive filtering problem for a class of networked linear time-varying systems subject to the scheduling of the random access protocol (RAP). The communication between the sensor nodes and the remote filter is implemented via a shared network. For the purpose of preventing the data from collisions, only one sensor node is allowed to get access to the network at each time instant. The transmission order of sensor nodes is orchestrated by the RAP scheduling, under which the selected nodes obtaining access to the network could be characterized by a sequence of independent and identically-distributed variables. The aim of the addressed filtering problem is to design a recursive filter such that the filtering error covariance could be minimized by properly designing the filter gain at each time instant. The desired filter gain is calculated recursively by solving two Riccati-like difference equations. Furthermore, the boundedness issue of the corresponding filtering error covariance is investigated. Sufficient conditions are obtained to ensure the lower and upper bounds of the filtering error covariance. Two illustrative examples are given to demonstrate the correctness and effectiveness ofour developed recursive filtering approach.

This paper investigates the robust stability of uncertain linear neutral systems with time-varying discrete delay. A delay-dependent stability criterion is obtained and formulated in the form of a linear matrix inequality (LMI). Two numerical examples are given to indicate significant improvements over some existing results.

This paper is concerned with a Takagi-Sugeno (T-S) fuzzy dynamic positioning controller design for an unmanned marine vehicle (UMV) in network environments. Network-based T-S fuzzy dynamic positioning system (DPS) models for the UMV are first established. Then, stability and stabilization criteria are derived by taking into consideration an asynchronous difference between the normalized membership function of the T-S fuzzy DPS and that of the controller. The proposed stabilization criteria can stabilize states of the UMV. The dynamic positioning performance analysis verifies the effectiveness of the networked modeling and the controller design.

No abstract is provided for this article.

This paper is concerned with the H <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">∞</sub> filtering for sampled-data systems. First, an event-based data packet processor is introduced to release the sampled measurement outputs only if an event condition is violated. As a result, the communication resources can be significantly saved while the desired system performance can be preserved. Second, the resulting filtering error system is modeled as an interval time delay system. By employing Lyapunov-Krasovskii functional method, a new bounded real lemma (BRL) is formulated such that the filtering error system can achieve a prescribed H <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">∞</sub> performance level. Third, by performing an invertible linear transformation on the filtering error system, the corresponding BRL to the transformed filtering error system is obtained, from which, suitable H <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">∞</sub> filters and the threshold parameter in the event condition can be co-designed provided that a set of linear matrix inequalities are feasible. Finally, the effectiveness of the proposed method is demonstrated through a mechanical system with two masses and two springs.

The output feedback stabilization of polytopic-type uncertain discrete systems with interval-like time-varying state and input delays is studied. Based on a new bounding inequality technique, combining a parameter-dependent Lyapunov functional, a stability criterion is firstly presented in terms of a set of simple convex feasibility tests. Then, the output feedback stabilization conditions are formulated in the form of non-convex matrix inequalities, of which a feasible solution can be obtained by solving an LMI-based minimization problem. The newly proposed inequality lies in the partitioning idea of the varying interval and shows its more tightness over some existing bounding techniques. No free weighting matrix is involved. Two illustrative examples are finally given to verify the advantage and effectiveness of the proposed method.

This paper is concerned with event-triggered H∞ control of sampled-data systems. Its novelties lie in three aspects: (i) A novel accumulated-state-er

To solve the problem of the motion control of gecko-like robots in complex environments, a central pattern generator (CPG) network model of motion control was designed. The CPG oscillation model was first constructed using a sinusoidal function, resulting in stable rhythm control signals for each joint of the gecko-like robot. Subsequently, the gecko-like robot successfully walked, crossed obstacles and climbed steps in the vertical plane, based on stable rhythm control signals. Both simulations and experiments validating the feasibility of the proposed CPG motion control model are presented.