910 publications from this institution
This paper investigates the effect of a small time-delay on dynamic output feedback control of an offshore steel jacket structure subject to a nonlinear wave-induced force. First, a conventional dynamic output feedback controller is designed to reduce the internal oscillations of the offshore structure. It is found that the designed controller is of a larger gain in the sense of Euclidean norm, which demands a larger control force. Second, a small time-delay is introduced intentionally to design a new dynamic output feedback controller such that (i) the controller is of a small gain in the sense of Euclidean norm and (ii) the internal oscillations of the offshore structure can be dramatically reduced. It is shown through simulation results that purposefully introducing time-delays can be used to improve control performance.
No abstract is provided for this article.
This chapter is concerned with network-based distributed leader-following consensus for multi-agent systemsMulti-agent systems. A network-based consensus control protocol under a directed graphGraph is proposed, with which each agent can be remotely controlled...
As one of the major forms of geological disaster, landslides cause huge casualties and economic losses in China every year. Given the importance of landslide prediction, it is a challenging task due to difficulties in efficiently leveraging the spatial–temporal information for enhanced prediction. This paper presents a novel spatial–temporal enhanced CNN-GRU model to improve landslide predictions with the following contributions. First, this paper explicitly models the spatial correlation in the dataset and constructs a spatial–temporal time-sequence deformation prediction model that greatly improves landslide predictions. This model integrates the spatial correlation of monitoring points into time-series deformation prediction to improve the prediction of landslide deformation trends. Second, we develop a complete data processing pipeline involving SBAS-InSAR, time-series data preprocessing, spatial–temporal homogeneous point selection and weighting, as well as CNN-GRU model training. The pipeline is tailor-designed to leverage the spatial–temporal correlation in the data to enhance the prediction performance. Third, we apply the proposed model to monitor landslide deformation around Woda Village, Chamdo City, Tibet. The results show that the root mean square error (RMSE) of the monitoring points in the landslide area is reduced by about 20.9% and the number of points with an RMSE of less than 3 mm is increased by 12.9%, leading to a significant improvement in prediction accuracy.
No abstract is provided for this article.
In this paper, we investigate the event-triggered $$H_\infty $$ controller synthesis issue for vehicle suspension systems with linear fractional uncertaint
This paper addresses the problem of event-triggered scheduling and control for active suspension of uncertain quarter vehicle suspension systems over resource-constrained controller area network (CAN). The central aim is to develop an efficient dynamic event-triggered scheduling and control co-design approach for improving suspension performance, while significantly alleviating the resource occupancy over CAN in the simultaneous presence of transmission delays and data losses. To this end, two new dynamic event-triggered schedulers (DETSs) are first developed to orchestrate the transmissions of sensor data packets at each sampling time. One salient feature of the DETSs is that the dynamic variables employed in the relevant triggering laws can unremittingly adjust their values over time, which greatly favors the dynamic scheduling of data transmissions over CAN. Then, tractable criteria for stability and suspension performance analysis as well as criteria for co-designing the desired controllers and DETSs are derived. It is shown that the co-design criteria enable comprehensive trade-off analysis between network quality of service and control quality of performance and communication efficiency. Finally, simulation results for a two-degree-of-freedom quarter vehicle model demonstrate possible improvements on ride comfort, good road holding, limited suspension stroke and actuator force, meanwhile saving a large portion of communication resource expenditure.
In this paper, the joint input and state estimation problem is considered for linear discrete-time stochastic systems. An event-based transmission scheme is proposed with which the current measurement is released to the estimator only when the difference from the previously transmitted one is greater than a prescribed threshold. The purpose of this paper is to design an event-based recursive input and state estimator such that the estimation error covariances have guaranteed upper bounds at all times. The estimator gains are calculated by solving two constrained optimisation problems and the upper bounds of the estimation error covariances are obtained in form of the solution to Riccati-like difference equations. Special efforts are made on the choices of appropriate scalar parameter sequences in order to reduce the upper bounds. In the special case of linear time-invariant system, sufficient conditions are acquired under which the upper bound of the error covariance of the state estimation is asymptomatically bounded. Numerical simulations are conducted to illustrate the effectiveness of the proposed estimation algorithm.
A method to derive an order-2 <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">N</sup> integer cosine transform is presented in this paper. The proposed transform has orthogonal basis vectors and inherits the recursive structure from the discrete cosine transform such that an order-2 <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">N</sup> transform can be derived from an order-2 <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">(N-1</sup> transform. In this paper, transforms up to order 32 are derived and implemented into High Efficiency Video Coding reference model HM13.0. Compared with the core transform in HM13.0, the proposed transform has more flexibility and lower complexity for implementation while providing almost the same coding performance.
In this paper, we propose a temporal layer adaptive loop filter (TLAF), which suppresses the quantization noise adaptively to the characteristics of frames at different temporal layer. The proposed filter unifies two different modes of Kuan's filter which is an efficient linear minimum mean square error (LMMSE) estimator. Block-based non-local Kuan's filter (BNLK) is applied on frames at lower temporal layer in transform domain while pixel-based non-local Kuan's filter (PNLK) is applied on frames at higher temporal layer in spatial domain. Experimental results show that when compared with HEVC main profile, the proposed loop filter achieves on average 3.1%, 2.1% and 2.1% bit rate reduction at mode all-intra, random-access and low-delay B respectively in combination with better visual quality around edges and textures.
This paper is concerned with network-based control for an offshore steel jacket platform with an active tuned mass damper mechanism. A network-based dynamic model of the offshore platform is presented first. Then, a network-based state feedback control scheme is developed. Based on a proposed Lyapunov-Krasovskii functional, a delay-dependent stability criterion for the offshore platform system is derived, and a sufficient condition for the existence of the network-based controller is developed. It is found through simulation results that the oscillation amplitudes of the offshore steel jacket platform under the network-based feedback controller are smaller than the ones under the nonlinear controller, and the control force required by the former is much smaller than the one by the latter.
This paper is concerned with stochastic stability, l 1-gain performance analysis and positivity-preserving l 1-gain controller design for a positive discrete-time Markov jump linear system with time-delay. First, necessary and sufficient conditions for stochastic stability of the system are derived by constructing a linear co-positive stochastic Lyapunov functional and establishing a system equation whose state variables consist of the mathematical expectation of the markovianized states and whose coefficient matrices depend on time-delay and the transition probability. It is revealed that stochastic stability of the positive discrete-time Markov jump linear system with time-delay is influenced by the size of time-delay and it is demonstrated by an example that the effect of time-delay on stochastic stability can be either positive or negative. Second, exact computation on an l 1-gain index of a stochastically stable positive discrete-time Markov jump linear system with time-delay is presented, and a necessary and sufficient condition for the l 1-gain performance is derived in the form of linear programming. Third, an iterative algorithm is proposed to design a positivity-preserving l 1-gain controller, and in single-input case, an optimal controller is obtained analytically such that the closed-loop system achieves the minimal l 1-gain performance. Then, a modified pest’s structured population dynamic model is developed to illustrate the effectiveness of the designed method.
This paper is concerned with robust stabilization for a class of T–S fuzzy control systems with interval time-varying delays. An approach is proposed to significantly improve the system performance while reducing the number of scalar decision variables in linear matrix inequalities. The main points of the approach are: (i) two coupling integral inequalities are proposed to deal with some integral items in the derivation of the stability criteria; (ii) an appropriate Lyapunov–Krasovskii functional is constructed by including both the lower and upper bounds of the interval time-varying delays; and (iii) neither model transformation nor free weighting matrices are employed in the theoretical result derivation. As a result, some improved sufficient stability criteria are derived, and the maximum allowable delay bound and controller gains can be obtained simultaneously by solving an optimization problem. Numerical examples are given to demonstrate the effectiveness of the proposed approach.
