共查询到20条相似文献,搜索用时 234 毫秒
1.
A binary available bit rate (ABR) scheme based on discrete-time variable structure control (DVSC) theory is proposed to solve the problem of asynchronous transfer mode (ATM) networks congestion in this paper. A discretetime system model with uncertainty is introduced to depict the time-varying ATM networks. Based on the system model, an asymptotically stable sliding surface is designed by linear matrix inequality (LMI). In addition, a novel discrete-time reaching law that can obviously reduce chatter is also put forward. The proposed discrete-time variable structure controller can effectively constrain the oscillation of allowed cell rate (ACR) and the queue length in a router. Moreover, the controller is self-adaptive against the uncertainty in the system. Simulations are done in different scenarios. The results demonstrate that the controller has better stability and robustness than the traditional binary flow controller, so it is good for adequately exerting the simplicity of binary flow control mechanisms. 相似文献
2.
自适应比特(available bit rate,简称ABR)业务的流量控制是ATM网络中一种有效的拥塞控制机制和流量管理手段.在高速的ATM网络中,算法的简洁性在很大程度上决定着交换机的性能.尽管二进制ABR流量控制的简洁性具有相当大的吸引力,但标准的EFCI算法控制的队列长度和允许信元速率(allowed cell rate,简称ACR)却容易出现大幅振荡的现象,这势必会降低链路的利用率,严重影响交换机的性能.进而又有了相对复杂却有效的显式速率反馈机制.在此研究中,以已有的ABR流量控制模型为基础,应用概率拥塞判定机制,并借助鲁棒控制理论中滑模变结构控制器的设计方法,为ABR流量控制设计了一种新的二进制算法,避免了标准EFCI算法中非线性环节诱发的自激振荡,这对于充分发挥二进制流控算法的简洁性以及优化交换机的性能是极为有利的.仿真实验表明:二进制流量控制中的滑模变结构算法大幅度地抑制了ACR和队列的振荡,平滑了由此而引入的时延抖动,为实现ATM网络中的服务质量提供了可靠的实现机制. 相似文献
3.
4.
Robust discrete variable structure control with finite-time approach to switching surface 总被引:1,自引:0,他引:1
Chih-Lyang Hwang 《Automatica》2002,38(1):167-175
By using a dead-beat control technique of discrete-time systems, a robust discrete variable structure control (DVSC) is developed for the linear discrete-time systems subject to input disturbance, measurement noise and uncertainty. The proposed control includes two parts: equivalent control and switching control. Based on the internal model principle, the input disturbance and the measurement noise modeled as pulse transfer functions, are rejected by the equivalent control. The unmatched uncertainty caused by the time-invariant parameter variations is also tackled by the equivalent control. If the inverse of stable characteristic polynomial of the real closed-loop system is a finite-degree polynomial, the trajectory reaches the switching surface in a finite-time step. Due to the subjection of input disturbance or measurement noise or uncertainty, a poor response occurs. Under these circumstances, a switching control based on Lyapunov redesign is employed to improve the system performance. The stability of the closed-loop system is then verified by Lyapunov stability theory. Simulations are also given to confirm the usefulness of the proposed controller. 相似文献
5.
针对一类离散时间系统,提出一种变结构控制设计方法。为了减小离散指数趋近律的抖振现象,本文构造一种趋近律, 利用它设计变结构控制器,能够大幅度削弱抖振,有效地改善控制品质,使系统最终趋于原点,并使系统稳定。给出数值计算和仿真算例。 相似文献
6.
This paper proposes a neural network (NN)-based adaptive control methodology to prevent congestion in high-speed asynchronous transfer mode (ATM) networks. The buffer dynamics at the switch is modeled as a nonlinear discrete-time system and a NN-based predictive controller is designed to predict the explicit values of the transmission rates of the sources so as to prevent congestion. Tuning methods are provided for the NN weights to estimate the unpredictable and statistically fluctuating network traffic. Mathematical analysis is given to demonstrate the stability of the closed-loop system so that a desired quality of service (QoS) can be guaranteed. The QoS is defined in terms of cell loss ratio (CLR) and latency.We derive design rules mathematically for selecting the NN tuning algorithm such that the desired performance is guaranteed during congestion and potential tradeoffs are shown. Simulation results are provided to justify the theoretical conclusions for single source/single switch scenario using ON/OFF data. Finally, comparison studies are also included to show the effectiveness of the proposed method over conventional rate-based and thresholding techniques during simulated congestion. 相似文献
7.
On discrete-time variable structure sliding mode control 总被引:1,自引:0,他引:1
The purpose of this paper is to show the limitations of discrete-time variable structure sliding mode control and that the equivalent control must be used in order to have sliding in a neighborhood of the switching surface. Conflicting requirements for the sliding mode controller behavior in the continuous and discrete-time domains are revealed and analyzed. A linear control law for an uncertain discrete-time linear plant, with bounded uncertainties, is analyzed and its superiority over nonlinear controllers is demonstrated. The conclusion of the obtained results is that in the discrete-time variable structure sliding mode controller design, unlike in the continuous-time, the designer may have limited flexibility in selecting controller architectures. 相似文献
8.
A robust stability criterion for multivariable discrete-time variable structure control is proposed. When a variable structure controller is designed and implemented as a sampled-data system, achieving robustness to uncertainties can become difficult. To ameliorate the situation, an uncertainty estimator, also formulated within the variable structure framework, can be used as an embedded discrete-time variable structure controller. This approach requires a bounded changing rate of the uncertainties to ensure robust stability. However, when uncertainties vary as a function of state variables, which occurs with parametric uncertainties, it is not practical to assume such a bound. In this paper, uncertainties are assumed to consist of external disturbances and parametric uncertainties. An uncertainty compensator is used to deal with the former, and a robust stability criterion is developed using the small gain theorem for the latter. 相似文献
9.
10.
The robust H∞ control problem for discrete-time uncertain systems is investigated in this paper. The uncertain systems are modelled as a polytopic type with linear fractional uncertainty in the vertices. A new linear matrix inequality (LMI) characterization of the H∞ performance for discrete systems is given by introducing a matrix slack variable which decouples the matrix of a Lyapunov function candidate and the parametric matrices of the system. This feature enables one to derive sufficient conditions for discrete uncertain systems by using parameter-dependent Lyapunov functions with less conservativeness. Based on the result, H∞ performance analysis and controller design are carried out. A numerical example is included to demonstrate the effectiveness of the proposed results. 相似文献
11.
Adaptive control based on IF–THEN rules for grasping force regulation with unknown contact mechanism
An industrial gripping application with unknown contact mechanism is considered as a class of unknown nonlinear discrete-time systems. The control scheme is developed by an adaptive network called multi-input fuzzy rules emulated network (MiFREN) within discrete-time domain. The network structure is directly constructed regarding to IF–THEN rules related to gripper and contact mechanism properties. All adjustable parameters require only the on-line learning phase to improve the closed loop performance. The time varying learning rate is devised for gradient reach with the proof of stability analysis. Furthermore, the estimated sensitivity of system dynamic is directly considered within the parameter adaptation. The experimental system with an industrial parallel grip model WSG-50 validates the performance of the proposed controller. 相似文献
12.
离散时间系统变结构拟滑模控制改进算法 总被引:3,自引:3,他引:0
传统的离散时间变结构控制律均是以等效控制为基础,长期的应用表明这种没计思想欠合理.针对该问题,设计了离散时间系统变结构滑模控制的一种新算法.算法针对前人所提出的控制算法不足之处,对离散时间滑模控制量设计进行了改进.理论分析表明,所提出的控制算法满足离散时间变结构系统到达条件的要求,通过选择合适的滑模切换函数以及控制律参数,保证系统的轨线快速落在滑模面上,有效地缩短了系统状态到达滑动模态的时间,且抖振小.仿真结果表明,使用改进控制算法的系统输出响应优于未改进算法情况,响应速度较快,证明了所提出的算法是可行的、有效的. 相似文献
13.
Do Wan Kim Author Vitae 《Automatica》2009,45(6):1518-1523
This paper concerns the stability of a sampled-data Takagi-Sugeno (T-S) fuzzy control system with quantization, when a controller design is based on an approximate discrete-time model of the plant without quantization. The motivations come from the facts that digital devices for interfacing a plant with a controller quantize signals and an exact discrete-time model of the T-S fuzzy system is generally not amenable to synthesis process. We show that the concerned system is Lagrange stabilizable by the controller asymptotically stabilizing the approximate discrete-time model. A constructive design algorithm for the developed stability analysis is proposed in terms of linear matrix inequalities. 相似文献
14.
Guaranteed Cost Control for Discrete-time Singular Large-scale Systems with Parameter Uncertainty 总被引:1,自引:0,他引:1
WO Song-Lin~ 《自动化学报》2005,(5)
The problem of optimal guaranteed cost control for discrete-time singular large-scale systems with a quadratic cost function is considered in this paper.The system under discussion is subject to norm bounded time-invariant parameter uncertainty in all the matrices of model.The problem we address is to design a state feedback controller such that the closed-loop system not only is robustly stable but also guarantees an adequate level of performance for all admissible uncer- tainties.A sufficient condition for the existence of guaranteed cost controllers is presented in terms of linear matrix inequalities(LMIs),and a desired state feedback controller is obtained via con- vex optimization.An illustrative example is given to demonstrate the effectiveness of the proposed approach. 相似文献
15.
The problem of optimal guaranteed cost control for discrete-time singular large-scale systems with a quadratic cost function is considered in this paper. The system under discussion is subject to norm bounded time-invariant parameter uncertainty in all the matrices of model. The problem we address is to design a state feedback controller such that the closed-loop system not only is robustly stable but also guarantees an adequate level of performance for all admissible uncertainties. A sufficient condition for the existence of guaranteed cost controllers is presented in terms of linear matrix inequalities (LMIs), and a desired state feedback controller is obtained via convex optimization. An illustrative example is given to demonstrate the effectiveness of the proposed approach. 相似文献
16.
Discrete-time neural network output feedback control of nonlinear discrete-time systems in non-strict form 总被引:1,自引:0,他引:1
J. Vance Author Vitae Author Vitae 《Automatica》2008,44(4):1020-1027
An adaptive neural network (NN)-based output feedback controller is proposed to deliver a desired tracking performance for a class of discrete-time nonlinear systems, which are represented in non-strict feedback form. The NN backstepping approach is utilized to design the adaptive output feedback controller consisting of: (1) an NN observer to estimate the system states and (2) two NNs to generate the virtual and actual control inputs, respectively. The non-causal problem encountered during the control design is overcome by using a dynamic NN which is constructed through a feedforward NN with a novel weight tuning law. The separation principle is relaxed, persistency of excitation condition (PE) is not needed and certainty equivalence principle is not used. The uniformly ultimate boundedness (UUB) of the closed-loop tracking error, the state estimation errors and the NN weight estimates is demonstrated. Though the proposed work is applicable for second order nonlinear discrete-time systems expressed in non-strict feedback form, the proposed controller design can be easily extendable to an nth order nonlinear discrete-time system. 相似文献
17.
一种离散时间系统变结构控制的新方法 总被引:2,自引:0,他引:2
研究离散时间系统变结构控制问题,提出一种新的离散变结构趋近律.利用该趋近律设计的离散变结构控制器,不仅能大幅度削弱抖振,使系统运动最终趋干原点不存在稳态振荡,而且可使系统的准滑动模态保持步步穿越切换面的基本属性,有效地改善了控制品质,提高了系统的鲁棒性.仿真结果验证了该方法的有效性与合理性. 相似文献
18.
Discrete-time sliding mode control is one of the most prominent robust control technique to stabilise systems. However, the assumption of full state feedback being available is seldom satisfied in practice. This paper presents the functional observer-based sliding mode controller (SMC) design for discrete-time stochastic systems with unmatched uncertainty. A disturbance-dependent sliding function method is proposed such that the effect of unmatched uncertainty of the system is minimised. Furthermore, SMC is calculated using the functional observer method. Finally, a simulation example is given to show the effectiveness of the proposed method. 相似文献
19.
Ramon Costa-Castelló 《Automatica》2006,42(9):1605-1610
This work proposes and studies a new repetitive controller for discrete-time systems which are required to track or to attenuate periodic signals. The main characteristic of the proposed controller is its passivity. This fact implies closed-loop stable behavior when it is used with discrete-time passive plants. The work also discusses the energetic structure, the frequency response and the time response of the proposed controller structure. A numerical example is included to illustrate its practical use. 相似文献