An operating system for a fault-tolerant multiprocessor controller

The development of an operating system that is a central component of a fault-tolerant multiprocessor is described. The operating system, while relatively simple and small, supports multitasking and multiprocessing, as well as both self-diagnostics and cross-diagnostics for fault detection. In the event of a fault, the system permits rapid reconfiguration in a manner that retains processing for the highest-priority tasks. Since the hardware needed to provide fault tolerance is available when there are no faults, the operating system can utilize this excess capacity to accomplish lower-priority tasks during normal operation. This approach yields graceful degradation in response to faults in the system components     

同时镇定及鲁棒控制器存在条件

在保证闭环系统稳定的前提下,将被控对象看成控制器,控制器看成被控对象。从集合的角度研究了镇定区间对象族的控制器存在条件和设计方法,利用值集的概念和Youla参数化结果给出了镇定区间对象族控制器存在的充分条件．在强约束条件下,得到了控制器存在的充要条件．最后给出了鲁棒镇定控制器的设计方法．     

Synthesis of a linearly interpolated gain scheduling controller for large flexible spacecraft ETS-VIII

This paper illustrates a design procedure for a linearly interpolated gain scheduling controller for Engineering Test Satellite VIII (ETS-VIII) using its linear parameter-varying (LPV) model. The LPV model here consists of piecewise-linear functions of the paddle rotation angle and a norm-bounded perturbation. The main purpose of this research is to derive a simple structured scheduling law that can be easily implemented in a satellite onboard computer. The derived gain has only two grid points and is scheduled simply by linear interpolation, which is desirable from the standpoint of implementability. Moreover, since the synthesis condition is based on parameter-dependent Lyapunov functions, it gives less conservative results than existing methods. Simulation results are presented to show the effectiveness of the proposed synthesis.     

Problem of invariance for discrete stabilization systems operating in conditions of regular chaos

New models of maps oriented to the solution of invariance problems in discrete dynamic systems that operate in conditions of deterministic chaos are proposed. The idea of K(E) transformation for quasi-stochastic sequences is developed based on these maps. The result is a method for the synthesis of discrete stabilization systems; this method, in combination with the principles of the classical theory of random processes, provides compensation for deterministic chaos and optimal filtering of stationary random noise.     

An exact solution to the stabilization of discrete systems using a first-order controller

An exact solution is derived for stabilizing a given but arbitrary, linear time-invariant discrete system by a first-order discrete-time feedback controller, which has received considerable attention in the past few years. An approach has been recently proposed to compute the first-order controllers, given in the form of C(z)=(zx/sub 1/+x/sub 2/)/(z+x/sub 3/). This approach derives the stabilizing set in the x/sub 1/-x/sub 2/ plane by fixing x/sub 3/, and then repeat the procedure by sweeping over all possible values of x/sub 3/. In this note, from the geometrical point of view, we present an exact solution to the problem.     

Adaptive stabilization using a nonlinear time-varying controller

Byrnes et al. (1986) showed that there is no smooth, finite-dimensional, nonlinear time-invariant (NLTI) controller which asymptotically stabilizes every finite-dimensional, stabilizable and detectable, linear time-invariant (LTI) plant (with a fixed number of inputs and outputs). Here we construct a finite-dimensional nonlinear time-varying (NLTV) controller which does exactly that; we treat both the discrete-time and continuous-time cases. With p equal to one in the discrete-time case and the number of plant outputs in the continuous-time case, we first show that for every stabilizable and detectable plant, there exists a p-dimensional linear time-varying (LTV) compensator which provides exponential stabilization; we then construct a (p+1)-dimensional NLTV controller which asymptotically stabilizes every admissible plant by switching between a countable number of such LTV compensators     

Planning plant operating procedures for chemical plant

All industrial plants require an extensive set of operating procedures. This paper discusses the use of hierarchical nonlinear least-commitment AI planning technology to generate plant operating procedures for chemical process plant. It considers the handling of flow through the interfacing of a valve sequencing subplanner, the handling of safety through the mechanism of goals of prevention, and the use of pairs as a way of mutually constraining planning variables and increasing planning efficiency. It concludes with some results and discussion of the advantages of the approach.     

增强耦合的TORA系统镇定控制方法设计

针对欠驱动TORA系统,设计一种镇定控制器和增强型耦合控制器。根据TORA系统的动力学模型,分析旋转小球与平移振荡器之间的耦合关系和系统的无源特性。构造一个新型的Lyapunov函数,并得到一种耦合镇定控制器。采用Lyapunov方法和LaSalle不变性原理证明了闭环系统的稳定性。最后,通过改进所设计的控制器得到一种增强型耦合控制器。仿真结果验证了所提出控制器的有效性和优越性。     

Sufficient lyapunov-like conditions for stabilization

In this paper we study the stabilizability problem for nonlinear control systems. We provide sufficient Lyapunov-like conditions for the possibility of stabilizing a control system at an equilibrium point of its state space. The stabilizing feedback laws are assumed to be smooth except possibly at the equilibrium point of the system.     

线性时变系统的一种鲁棒镇定控制器设计方法

针对一类线性时变系统提出一种状态反馈镇定控制器设计方法,该反馈控制器能将线性时变系统转化为一个稳定的定常闭环系统.借助线性系统的特征结构配置参数化方法,得到含待求参数的控制器解析形式,并给出控制器的可解性判据.在满足可解性的基础上,进一步对控制器进行了多目标优化设计,使其在保证系统稳定性的同时,具有良好的鲁棒性和干扰抑制能力.通过一个时变卫星姿态控制系统的实际设计表明了该方法的有效性.     

Exponential stabilization controller design for interconnected time delay systems

Decentralized robust control problem is investigated for a class of large scale systems with time varying delays. The considered systems have mismatches in time delay functions. A state coordinate transformation is first employed to change the original system into a cascade system. Then the virtual linear state feedback controller is developed to stabilize the first subsystem. Based on the virtual controller, a memoryless state feedback controller is constructed for the second subsystem. By choosing new Lyapunov Krasovskii functional, we show that the designed decentralized continuous adaptive controller makes the solutions of the closed-loop system exponentially convergent to a ball, which can be rendered arbitrary small by adjusting design parameters. Finally, a numerical example is given to show the feasibility and effectiveness of the proposed design techniques.     

Design of dynamic output feedback controller for power system stabilization

A computational method of designing dynamic compensators for stabilization of power systems is described. The control strategy only employs feedback from the available system output variables. A design procedure which would result in a stable closed-loop system over wide operating points is also included.     

Simultaneous stabilization of two discrete-time plants using a2-periodic controller

A generic method for designing a 2-periodic controller for the simultaneous placement of the closed-loop poles of two single-input-single-output discrete shift-invariant plants at the origin is presented. The method consists of first recasting the simultaneous pole-placement problem as one of solving a coupled pair of linear polynomial equations involving three unknown polynomials, and then obtaining the controller parameters in terms of the coefficients of these polynomials. The isolated cases for which such pole placement is not possible have been listed. Simulation results show that the performances of systems thus compensated are superior to their performances when compensated using the higher periodicity controllers suggested in literature     

Synthesis of discrete controller for construction of a distributed controller of temperature conditions of steam oil heater

A discrete controller for the thermal conditions of a distributed plant—a stream oil heater—is synthesized based on the spectral method and properties of spectral characteristics. A closed system of equations including the distributed plant and the controller with a spatially distributed stage heater is analyzed.     

球形对象族的最优鲁棒镇定

本文对球形对象族系统最优鲁棒镇定问题进行了研究.利用最小范数解方法求解球形对象族的可镇定性半径.可镇定性半径是系统稳定性半径的上界,最优控制器的稳定性半径等于镇定性半径.文中给出球形对象族最优鲁棒控制器的形式,并通过示例具体说明球形对象族最优鲁棒控制器的设计方法.     

Global stabilization of systems containing a double integrator using a saturated linear controller

In this paper, we present a Lyapunov function for systems containing a double integrator and with controller saturation. This Lyapunov function is composed of a positive-semidefinite quadratic term and an integral term. The main result provides a sufficient condition that guarantees a system with a double integrator can be globally stabilized by a saturating linear controller. For a triple-integrator system the saturated linear controller does not satisfy the sufficient condition, which agrees with the known result. Copyright © 1999 John Wiley & Sons, Ltd.     

Application of a fuzzy controller in a warm water plant

In many cases a human operator is far more successful in controlling a complex industrial process than a controller designed by modern control techniques. The method of expressing the strategy of a human operator using fuzzy set theory has already been proposed elsewhere. In this study this ethod is applied to the control of a warm water plant. Fuzzy algorithms based on linguistic rules describing the operator's control strategy are applied to control this plant. Several types of such algorithms are implmented and compared.     

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.     

Synthesis of a closed-loop combined plant and controller model

In practice, a controlled system consists of two distinct entities: the plant and the controller. These two entities are coupled by a feedback mechanism to give the closed-loop behavior of the controlled system. Under this structure, the controlled behavior of the system can be analyzed by simulation which is costly and time consuming. In this study, we synthesize a combined plant and controller model. We consider the practical issues and propose a method which combines the advantages of Petri nets (PN) and the supervisory controller design based on Formal Language Theory. The resultant combined model is a PN and represents the controlled closed-loop behavior of the system. This model can be used for the functional and the performance analysis of the system, verification of the controller and the control code generation.