输出多采样反馈控制器及系统稳定性

针对由连续被控对象和数字控制器构成的数字控制系统,将现有的线性系统输出多采样线性反馈数字控制器设计方法推广到非线性系统．并相应地研究了非线性输出多采样反馈控制器及摄动非线性系统．给出了这类非线性输出多采样数字控制系统及其摄动系统的稳定性和鲁棒性条件．     

Stability conditions for a heat transfer object control system with Schipanov controller under imperfections in the controller

We study stability conditions for a control system over a linear one-side bounded heat transfer object with the so-called “Schipanov controller”; this controller under perfect implementation must ensure invariant behavior of the object’s output related to the input influence. We study the behavior of the output of a closed system under such possible imperfections in controller implementation as pure delay and inertia; we find classes of influences with respect to which one can ensure stability of the closed system, and find estimates of its output’s response levels to influences from these classes.     

Controller switching based on output prediction errors

We consider a switched nonlinear feedback control strategy for controlling a plant with unknown parameters so that the output asymptotically tracks a reference signal. The controller is selected online from a given set of controllers according to a switching rule based on output prediction errors. For control problems requiring asymptotic tracking of a reference input we provide sufficient conditions under which the switched closed-loop control system is exponentially stable and asymptotically achieves good control even if the switching does not stop, Our results are illustrated with three examples     

变采样网络控制系统的鲁棒控制

对于线性时不变控制对象,在控制器和控制对象都采用时间-事件驱动时系统就变成便采样网络控制系统,当网络时延不确定时,在小于或者等于一个变采样周期时,基于动态输出反馈对变采样网络控制系统进行建模,使用李雅普诺夫方法和线性矩阵不等式研究了系统的鲁棒稳定性,并设计了鲁棒控制器,最后给出实例证明在鲁棒控制器的控制下系统稳定。     

Achievable behavior of general systems

A basic question in systems and control theory concerns the characterization of the set of all achievable closed-loop systems for a given plant system and a controller system to be designed. This problem is addressed in a general behavioral context. Sufficient, and often necessary, conditions for a behavior to be achievable are given, and for any achievable behavior a canonical controller is defined. The results generalize previously obtained results obtained for finite-dimensional linear systems. The application to nonlinear differential systems is outlined.     

输出时滞双率采样系统的鲁棒迭代学习控制

针对一类带有输出时滞的单输入单输出双率采样系统,提出一种鲁棒迭代学习控制算法.首先,利用提升技术将带有输出时滞的双率采样系统转化为无时滞形式的慢速率采样的状态空间模型,并基于二维(2D)系统理论,将迭代学习控制过程转化为等价2D模型;然后利用线性矩阵不等式(LMI)技术,给出确保系统稳定的充分条件和鲁棒控制器设计方法;最后,通过3层液位贮槽系统的液位控制仿真验证所提出方法的可行性和有效性.     

Adaptive actuator failure compensation control for MIMO systems*

Two adaptive failure compensation control schemes based on MRAC are developed for a class of MIMO LTI systems with unknown actuator failures. An effective controller structure is proposed to achieve the desired plant-model output matching when implemented with matching parameters. Design conditions are specified for such nominal plant-model output matching. Two adaptive versions of the nominal controller are proposed and stable adaptive laws are derived for updating the controller parameters when plant parameters and failure parameters are unknown. All closed-loop signals are bounded and the plant outputs track the given reference outputs asymptotically, despite the uncertainties in actuator failures and plant parameters. Simulation results for an aircraft lateral dynamic model verify the desired adaptive control system performance in the presence of unknown rudder and aileron failures.     

Synthesis of dissipative systems using quadratic differentialforms: part II

For pt.1 see ibid., p.53-69 (2002). The authors discuss several important special cases of the problem solved in Part I. These are: disturbance attenuation and passivation, the full information case, the filtering problem, and the case that the to-be-controlled plant is given in input-state-output representation. An interesting aspect is the notion of full information, which we define in terms of the observability of the to-be-controlled variables from the control variables. When the system is given in state space form, we obtain conditions for the existence of a controller that renders a system dissipative in terms of two coupled algebraic Riccati inequalities. The controller turns out to be a feedback system with a transfer function that is proper, but, in general, not strictly proper. Another issue that we study in this paper is feedback implementability. We find conditions under which, in the context of synthesis of dissipative systems, a controlled behavior can implemented by a feedback controller     

An adaptive control scheme for systems with unknown actuator failures

A state feedback output tracking adaptive control scheme is developed for plants with actuator failures characterized by the failure pattern that some inputs are stuck at some unknown fixed values at unknown time instants. New controller parametrization and adaptive law are developed under some relaxed system conditions. All closed-loop signals are bounded and the plant output tracks a given reference output asymptotically, despite the uncertainties in actuator failures and plant parameters. Simulation results verify the desired adaptive control system performance in the presence of actuator failures.     

Input-state model matching and ripple-free response for dual-rate systems

In this paper, we address the model matching problem for dual-rate systems where the controller output is generated at a faster rate than the measurement update rate. The model matching problem that has been studied in the literature requires the input-output properties of the closed-loop multirate system to match those of a desired single-rate linear time-invariant (LTI) system. In this paper, we consider the model matching problem from the input-state viewpoint: given a desired LTI system, find conditions and provide a controller design procedure to achieve matching between the closed-loop system and the desired system state variables at the measurement update rate. We provide a solution to this problem using a particular time-varying controller structure. In addition, we give conditions to avoid ripples in the steady-state output of the continuous-time plant; in particular, we show that some constraints on the input matrix of the desired system have to be posed. Numerical examples are given to illustrate the proposed method.     

Robust observer-based fuzzy control for variable speed wind power system: LMI approach

In this paper, the output-feedback control for stabilizing the uncertain nonlinear system is proposed. For achieving the robust stability, we deal with the parametric uncertainties of the concerned system which is based on the Takagi-Sugeno (T-S) fuzzy model. Also, we derive the observer-based models preserving the property and structure of the uncertainties. The sufficient conditions for output feedback stabilizing controller designs are given in terms of solutions to a set of linear matrix inequalities (LMIs). The simulation results for variable speed wind power (VSWP) system are demonstrated to visualize the feasibility of the proposed method.     

State and output feedback boundary control for a coupled PDE-ODE system

This note is devoted to stabilizing a coupled PDE-ODE system with interaction at the interface. First, a state feedback boundary controller is designed, and the system is transformed into an exponentially stable PDE-ODE cascade with an invertible integral transformation, where PDE backstepping is employed. Moreover, the solution to the resulting closed-loop system is derived explicitly. Second, an observer is proposed, which is proved to exhibit good performance in estimating the original coupled system, and then an output feedback boundary controller is obtained. For both the state and output feedback boundary controllers, exponential stability analyses in the sense of the corresponding norms for the resulting closed-loop systems are provided. The boundary controller and observer for a scalar coupled PDE-ODE system as well as the solutions to the closed-loop systems are given explicitly.     

Reference model selection and adaptive control for induction motordrives

An adaptive model-following speed controller for induction motor drives is proposed and implemented. This adaptive controller is easy to implement since, for the controlled plant, only the output signal is fed back. In order to choose a reference model with the desired drive dynamic behavior, a two-degree-of-freedom (2-DOF) controller is designed, using a systematic procedure based on the prescribed drive specifications. The reference model of the adaptive system is chosen as the transfer function of the controlled drive system by the 2-DOF controller in the nominal case. An adaptation signal is augmented to let the prescribed specifications be maintained under a wide range of operating conditions     

Stabilization, pole placement, and regular implementability

In this paper, we study control by interconnection of linear differential systems. We give necessary and sufficient conditions for. regular implementability of a given linear differential system. We formulate the problems of stabilization and pole placement as problems of finding a suitable, regularly implementable sub-behavior of the manifest plant behavior. The problem formulations and their resolutions are completely representation free, and specified only in terms of the system dynamics. Control is viewed as regular interconnection. A controller is a system that constrains the plant behavior through a distinguished set of variables, namely, the control variables. The issue of implementation of a controller in the feedback configuration and its relation to regularity of interconnection is addressed. Freedom of disturbances in a plant and regular interconnection with a controller also turn out to be inter-related     

不稳定零动态解开设计的鲁棒性

对零动态解开法用于输出反馈控制进行了详细分析,零动态解开法是一种回路变换法,通过变换将一个对不稳定对象进行镇定的控制器变换成对非最小相位系统的控制器.变换中虽然系统的特征方程式不变,但由于回路的结构已经改变,二者的鲁棒性并不等价.文中以一典型的非最小相位系统为例,详细分析了这种设计方法的鲁棒性.     

Input/output discrete event processes and communication delays

This paper proposes an input/output interpretation for the control of discrete event systems. In supervisory control theory, the plant is usually considered to be a process which spontaneously generates outputs. Its behavior is controlled by disabling some of its output events. In this paper the plant accepts inputs (commands) and generates outputs (responses). For many real-life problems, e.g., manufacturing problems, this model semantics seems more applicable than the original generator perspective proposed by Ramadge and Wonham. In real-life systems the message exchange between the plant and the controller is affected by communication delays. The class of supervisors that must be used in a closed-loop system subject to communciation delays is a subset of the set of solutions to the original problem introduced by Ramadge and Wonham. After having characterized this class of supervisors, the present paper states conditions on the plant language that allow the supervisors solving the (delay-free) supervisory control problem of Ramadge and Wonham to be used also for the case of closedloop systems affected by delays.     

基于模糊推理的汽车辅助驾驶系统控制算法

在建立汽车辅助驾驶系统模型的基础上,指出满足驾驶员的驾驶特征是车辆控制的一个重要指标,此外针对驾驶员驾驶行为的不精确性,提出了以模糊推理为基础的上位控制方法,并对其进行了现场实验。实验结果表明,用模糊控制理论模拟驾驶行为的不精确性是可行的。通过模糊控制自车的速度,能够实现自车在多种工况下保持安全状态。     

Single-input CMAC control system

This paper attempts to propose a single-input cerebellar model articulation controller (CMAC) control system, which contains only one controller implemented by the CMAC. The single-input CMAC control system adopts two learning stages. An off-line learning stage is to enable the output behavior of the CMAC to approximate the control surface of a fuzzy PD-type controller. An on-line learning stage follows to improve the system stability by the modified learning rule. The linear interpolation scheme is also applied to the recall process at the on-line learning stage to ensure better accuracy of the CMAC output. Simulation results show that the single-input CMAC controller is superior to the fuzzy PD-type controller.