Global Stabilization of Triangular Systems with Time-Delayed Dynamic Input Perturbations

A control design approach is developed for a general class of uncertain strict-feedback-like nonlinear systems with dynamic uncertain input nonlinearities with time delays. The system structure considered in this paper includes a nominal uncertain strict-feedback-like subsystem, the input signal to which is generated by an uncertain nonlinear input unmodeled dynamics that is driven by the entire system state (including unmeasured state variables) and is also allowed to depend on time delayed versions of the system state variable and control input signals. The system also includes additive uncertain nonlinear functions, coupled nonlinear appended dynamics, and uncertain dynamic input nonlinearities with time-varying uncertain time delays. The proposed control design approach provides a globally stabilizing delay-independent robust adaptive output-feedback dynamic controller based on a dual dynamic high-gain scaling based structure.Comment: 2017 IEEE International Carpathian Control Conference (ICCC

Decentralised delay-dependent static output feedback variable structure control

In this paper, an output feedback stabilisation problem is considered for a class of large scale interconnected time delay systems with uncertainties. The uncertainties appear in both isolated subsystems and interconnections. The bounds on the uncertainties are nonlinear and time delayed. It is not required that either the known interconnections or the uncertain interconnections are matched. Then, a decentralised delay-dependant static output feedback variable structure control is synthesised to stabilise the system globally uniformly asymptotically using the Lyapunov Razumikhin approach. A case study relating to a river pollution control problem is presented to illustrate the proposed approach

Model reference adaptive integral sliding mode control for switched delay systems

Makalenin ilk sayfası kayda eklenmiştir.This paper proposes a strategy of model reference adaptive integral sliding mode variable structure control to solve the tracking problem for a class of uncertain switched systems with time-varying delay. A stable integral sliding surface is first constructed. An adaptive control technique is used to adapt the unknown upper bounds of perturbations. Furthermore, adaptive variable structure controllers are employed such that the switched delay system containing perturbations with unknown upper bounds tracks the reference model under arbitrary switching signals. Finally, a numerical example is given to illustrate the effectiveness of the proposed design method

Topics in feedback control stabilization.

In this dissertation, we first show that for a class of uncertain nonlinear systems, the robust output feedback stabilizability is equivalent to the existence of robust output Lyapunov functions with the small control property. This is a generalization of a previous result of Tsinias and Kalouptsidis (1) (2). Then we construct state feedback and output feedback controls for some specific uncertain systems using either variable structure controls or continuous feedback controls. The feedback controls are designed to compensate for uncertainties and disturbances present in the systems. Some control designs are robust versions of those proposed by Gu (6)

Event-Triggered Variable Structure Control

This paper presents a novel Variable Structure Control (VSC) algorithm of Event- Triggered (ET) type, capable of dealing with a class of nonlinear uncertain systems. By virtue of its ET nature, the algorithm can be used as the kernel of a robust networked control system. The design objective is indeed to reduce the number of transmissions over the network. This has to be done while guaranteeing that the proposed ET-VSC is a stabilizing law with appropriate robustness property in front of matched uncertainties, even in presence of delayed transmissions. The proposed algorithm is theoretically analyzed in the paper, proving that the sliding variable associated with the controlled system results in being ultimately confined into a boundary layer of prescribed amplitude. As a consequence, it is proved that the state of the considered uncertain nonlinear system is ultimately bounded as well. Moreover, a lower bound for the time elapsed between consecutive triggering events is provided, which excludes the notorious Zeno behavior. Finally, the designed event- triggered variable structure control scheme is satisfactorily assessed in simulation

Robust sliding mode‐based extremum‐seeking controller for reaction systems via uncertainty estimation approach

"This paper deals with the design of a robust sliding mode‐based extremum‐seeking controller aimed at the online optimization of a class of uncertain reaction systems. The design methodology is based on an input–output linearizing method with variable‐structure feedback, such that the closed‐loop system converges to a neighborhood of the optimal set point with sliding mode motion. In contrast with previous extremum‐seeking control algorithms, the control scheme includes a dynamic modelling‐error estimator to compensate for unknown terms related with model uncertainties and unmeasured disturbances. The proposed online optimization scheme does not make use of a dither signal or a gradient‐based optimization algorithm. Practical stabilizability for the closed‐loop system around to the unknown optimal set point is analyzed. Numerical experiments for two nonlinear processes illustrate the effectiveness of the proposed robust control scheme.

Robust holographic control of complex interconnected systems with similar structure

With development of scientific technology, the scale of engineering systems is more and more large. It is required that people must deal with some complicated systems and finish complicated tasks under complicated surroundings. Theorefore, we must face complicated systems seriously. In recent years, some new research methods such as mordern geometric method and differential algebra method have been applied to the study of control theory according to the development of nonlinear science, and it is possible for us to solve complicated enginering systems with the development of computer science, which promotes the investigation of complicated control systems. Now, We must recognize clearly that investagations of complicated systems will be a long-term and arduous task, and it is not possible to find a valid method to deal with general complicated control systems in recent decads. But we think that to study some complicated systems with special structure at first, then, to study general complicated control systems may be a kind of valid method. In this paper, based on the thoughts above, a class of complicated nonlinear control systems with similar structure is considered, and problems of structural holographic control and robust control are studied It is shown that both the theoretic analyzes and systems engineering design are able to be simplified by using similar structure of systems, and holographic property is closely connected with similar structure. The paper may be summarized as follows: In the first chapter, fundmental characteristics of general complicated systems are introduced and similar structure of complicated control systems is described. Then, some practical examples are given to illustrate the wide existences of similar systems. Finally, controllers with holographic structure are presented. In the second chapter, state feedback centralized controllers with holographic structure are designed for some similar systems such as nonlinear time-varying composite systems, nonlinear uncertain composite systems with isolated subsystems which are singal input linear systems or input-state decoupling systems, and parametric matched uncertain composite systems with isolated systems possessing uniform relative degrees. Then, state feedback decentralized controllers with holographic structure are designed for nonlinear similar large-scale systems with unmatched uncertainties. Because the controllers designed in this chapter are similar to"Bang-Bang"control and of holographic structure, it is easy to be designed in practical engineering systems. In the third chapter, observer design of similar systems is considered. First, a kind of robust variable-structure observer is proposed for"matched"uncertain composite systems. Then, an asympototic observer is designed for composite systems with the isolated subsystems possessing general nonlinear systems by using mordern differential geometric method. It is shown that observer design can be simplified by using similar structure of systems. In chapter 4, observer-based stabilization for nonlinear similar composite systems is discussed. The obtained results are applied to disc-shift systems. Simulation shows that the resuts are effective. In chapter 5, output feedback controllers with holographic structure for nonlinear composite systems are given to be used to stabilize the systems. The advantages of this chapter are that uncertaities involved in the chapter are unmatched, and the controllers are not only decentralized but also holographic. So it's of great pratical value In chapter 6, some tracking problems are considered. A kind of iterative learning control problem is studied for a class of nonlinear similar composite systems in section 1, and robust variable structure controller is proposed for a class of similar large scale systems with matched uncertainties to track desired output in section 2. Some problems to be investigated late and good prospects of the study of similar systems are proposed to conclude the paper

Finite-Time Output Feedback Controller Based on Observer for the Time-Varying Delayed Systems: A Moore-Penrose Inverse Approach

This study proposes a novel variable structure control (VSC) for the mismatched uncertain systems with unknown time-varying delay. The novel VSC includes the finite-time convergence sliding mode, invariance property, asymptotic stability, and measured output only. A necessary and sufficient condition guaranteeing the existence of sliding surface is given. A novel lemma is established to deal with the control design problem for a wider class of time-delay systems. A suitable reduced-order observer (ROO) is constructed to estimate unmeasured state variables of the systems. A novel finite-time output feedback controller (FTOFC) is investigated, which is based on the ROO tool and the Moore-Penrose inverse technique. Moreover, with the help of this lemma and the proposed FTOFC, restrictions on most existing works are also eliminated. In addition, an asymptotic stability analysis is implemented by means of the feasibility of the linear matrix inequalities (LMIs) and given desirable sliding mode dynamics. Finally, a MATLAB simulation result on a numerical example is performed to show the effectiveness and advantage of the proposed method