Linear optimal control of continuous time chaotic systems

In this research study, chaos control of continuous time systems has been performed by using dynamic programming technique. In the first step by crossing the response orbits with a selected Poincare section and subsequently applying linear regression method, the continuous time system is converted to a discrete type. Then, by solving the Riccati equation a sub-optimal algorithm has been devised for the obtained discrete chaotic systems. In the next step, by implementing the acquired algorithm on the quantized continuous time system, the chaos has been suppressed in the Rossler and AFM systems as some case studies.     

Adaptive control for a class of MIMO nonlinear time delay systems against time varying actuator failures

This paper investigates an adaptive controller for a class of Multi Input Multi Output (MIMO) nonlinear systems with unknown parameters, bounded time delays and in the presence of unknown time varying actuator failures. The type of considered actuator failure is one in which some inputs may be stuck at some time varying values where the values, times and patterns of the failures are unknown. The proposed approach is constructed based on a backstepping design method. The boundedness of all the closed-loop signals is guaranteed and the tracking errors are proved to converge to a small neighborhood of the origin. The proposed approach is employed for a double inverted pendulums benchmark and a chemical reactor system. The simulation results show the effectiveness of the proposed method.     

A novel anti-windup framework for cascade control systems: An application to underactuated mechanical systems

This paper describes the anti-windup compensator (AWC) design methodologies for stable and unstable cascade plants with cascade controllers facing actuator saturation. Two novel full-order decoupling AWC architectures, based on equivalence of the overall closed-loop system, are developed to deal with windup effects. The decoupled architectures have been developed, to formulate the AWC synthesis problem, by assuring equivalence of the coupled and the decoupled architectures, instead of using an analogy, for cascade control systems. A comparison of both AWC architectures from application point of view is provided to consolidate their utilities. Mainly, one of the architecture is better in terms of computational complexity for implementation, while the other is suitable for unstable cascade systems. On the basis of the architectures for cascade systems facing stability and performance degradation problems in the event of actuator saturation, the global AWC design methodologies utilizing linear matrix inequalities (LMIs) are developed. These LMIs are synthesized by application of the Lyapunov theory, the global sector condition and the _?2${?}_2$ gain reduction of the uncertain decoupled nonlinear component of the decoupled architecture. Further, an LMI-based local AWC design methodology is derived by utilizing a local sector condition by means of a quadratic Lyapunov function to resolve the windup problem for unstable cascade plants under saturation. To demonstrate effectiveness of the proposed AWC schemes, an underactuated mechanical system, the ball-and-beam system, is considered, and details of the simulation and practical implementation results are described.     

多模型自适应广义预测控制及其在电厂汽温系统中的应用仿真

针对火电厂变负荷机组汽温系统动态特性的时变大迟延特点,首先给出了广义预测控制律的简化算法,在此基础上提出多模型广义预测控制方案。分析了多固定模型的选取问题,给出了在特定工况下的模型选择依据。仿真结果证实了算法的有效性。     

On robust stability of linear time invariant fractional-order systems with real parametric uncertainties

In this paper, the robust bounded-input bounded-output stability of a large class of linear time invariant fractional order families of systems with real parametric uncertainties is analyzed. The transfer functions contain polynomials in fractional powers of the Laplace variable s, possibly in combination with exponentials of fractional powers of s. Using the concept of the value set and a generalization of the zero exclusion condition theorem, a theorem to check the robust bounded-input bounded-output stability of these families of systems is presented. An upper cutoff frequency for drawing the value sets is provided as well. Finally, two numerical examples are given to illustrate results obtained by the lemma and theorems presented in the paper.     

Model-free adaptive fractional order control of stable linear time-varying systems

This paper presents a new model-free adaptive fractional order control approach for linear time-varying systems. An online algorithm is proposed to determine some frequency characteristics using a selective filtering and to design a fractional PID controller based on the numerical optimization of the frequency-domain criterion. When the system parameters are time-varying, the controller is updated to keep the same desired performances. The main advantage of the proposed approach is that the controller design depends only on the measured input and output signals of the process. The effectiveness of the proposed method is assessed through a numerical example.     

H2 consensus control of time-delayed multi-agent systems: A frequency-domain method

An analytical H2 controller design approach of homogeneous multi-agent systems with time delays is presented to improve consensus performance. Firstly, a closed-loop multi-input multi-output framework in frequency domain is introduced, and a consensus tracking condition is given. Secondly, the decomposition method is utilized to simplify the analysis of internal stability and H2 performance index of the whole system to a set of independent optimization problems. Finally, the H2 optimal controller can be computed from all the stabilizing controllers. The contributions of the new approach are that the design procedure is conducted analytically for arbitrary delayed multi-agent systems, and a simple quantitative tuning way is developed to trade off the nominal performance and robustness. The simulation examples show the effectiveness of the proposed control strategy.     

Robust finite time cooperative control of second order agents:A Multi-input Multi-output higher order super-twisting based approach

This paper studies the formation of multiple mobile agents with double integrator dynamics and their target tracking. An algorithm consisting of an observer and a feedback control law of the nonsmooth type is proposed for the purpose of achieving finite-time formation and target tracking. The development is based on the Multi-input Multi-output (MIMO) super-twisting like approach aiming at finite time convergence without chattering. In addition to the formation; tracking, chattering prevention and robustness is also provided by the sliding mode mechanism which is demonstrated by simulations.     

A novel approach to periodic event-triggered control: Design and application to the inverted pendulum

In this paper, periodic event-triggered controllers are proposed for the rotary inverted pendulum. The control strategy is divided in two steps: swing-up and stabilization. In both cases, the system is sampled periodically but the control actions are only computed at certain instances of time (based on events), which are a subset of the sampling times. For the stabilization control, the asymptotic stability is guaranteed applying the Lyapunov–Razumikhin theorem for systems with delays. This result is applicable to general linear systems and not only to the inverted pendulum. For the swing-up control, a trigger function is provided from the derivative of the Lyapunov function for the swing-up control law. Experimental results show a significant improvement with respect to periodic control in the number of control actions.     

预测函数控制在工业锅炉燃烧系统上的应用

通过将预测函数控制应用于链条锅炉燃烧控制的系统仿真，结果表明这种控制器具有较强的适应性和鲁棒性，而互有较高的控制精度。     

连续控制系统数字再设计

本文对连续控制系统数字再设计的3种方法－离散状态匹配法,双线性变换法,局部最优化进行比较研究,给出了仿真结果,仿真结果表明：局部最优法优于前种方法,数字再设计系统的状态在很短的时间内就能稳定。     

Optimistic value based optimal control for uncertain linear singular systems and application to a dynamic input-output model

In this paper, optimal control problems for uncertain discrete-time singular systems and uncertain continuous-time singular systems are considered under optimistic value criterion. The above singular systems are assumed to be regular and impulse-free, and optimistic value method is employed to optimize uncertain objective functions. Firstly, based on Bellman's principle of optimality, a recurrence equation is presented for settling optimal control problems subject to uncertain discrete-time singular systems. Then, by applying the principle of optimality and uncertainty theory, an equation of optimality for an optimal control model subject to an uncertain continuous-time singular system is derived. The optimal control problem can be settled through solving the equation of optimality. Two numerical examples and a dynamic input-output model are given to show the effectiveness of the results obtained.     

FMS中AGV的实时控制系统设计与实现

将AGV控制系统作为FMS控制系统中的一个通用组件来研究其建模与设计方法.首先,采用面向对象Petri网建模技术建立了AGV控制组件的动态模型.其次,进行了AGV控制组件与FMS中其它组件的基于CORBA的通信接口的定义.在此基础上,为了使AGV控制组件具有良好的维护性、重用性和柔性,建立了AGV控制组件的面向对象类的统一建模语言(UML)模型.最后进行了AGV控制组件设计和开发.     

Ionospheric delay contribution to the uncertainty of time and frequency measurements by one-way satellite time transfer method

The results of international time and frequency comparisons between INPL reference and BIPM using GPS satellite system are presented. The uncertainty of time and frequency comparison by the one-way satellite time transfer method is discussed. Ionospheric delay contribution to this uncertainty is evaluated. The diurnal, seasonal and long-term variations of ionospheric delay are presented and discussed. Ionospheric delay has daily and seasonal oscillations with amplitudes of about 20–60 and 20 ns, respectively. These oscillations are due to variations of solar activity and the variations of total electron content in ionosphere. Long-term variations of ionospheric delay correlate with 11-year sunspot cycle. The difference between ionospheric delay values at minimum (in 1996) and maximum (in 2002) solar activity is 3 times. The increased values of ionospheric delay have caused the increase of the standard deviation of the time comparison results in the same proportion.     

Static and low order anti-windup synthesis for cascade control systems with actuator saturation: An application to temperature-based process control

In this paper, a new framework for designing static and low order anti-windup compensator (AWC) for industrial cascade control systems with actuator saturation constraint is presented. Based on less conservative block diagonal quadratic Lyapunov function, sector boundedness, decoupled architecture, norm reduction and cascade loop compensation, linear matrix inequalities are developed which guarantee stability and suitable performance for overall closed-loop system. Static AWC parameters are obtained by comparing the full order AWC architecture with generalized architecture for cascade control system. Low order AWC is designed by sub-optimal approach in which AWC weights are tuned by designer. Anti-windup compensator is divided into inner and outer loop compensators which compensate the effect of saturation at each level. It is observed that the proposed methodology is less conservative than the traditional AWC schemes when applied to cascade control systems. The proposed scheme is successfully tested experimentally on a temperature-based process control system and results are outlined.     

Functional testing of measurement-based control systems: An application to automotive

The number of measurement-based embedded systems increases continuously in automotive, avionic, defense, and communication industries. In order to ensure the system’s compliance with requirements, adequate solutions for functional testing are needed. The paper describes an original approach for the functional validation of measurement-based complex control systems. The main focus is on the automatic generation of realistic continuous data sets (test stimuli) within the operational ranges of the measurement system under test, by applying enhanced statistical techniques, which are able to reproduce both timing and data dependencies. A thorough case study using an air fuel ratio control system from the automotive domain is performed to assess the approach. Results indicate that the proposed method is suitable for automated functional testing of embedded control systems within a Software-in-the-Loop test environment.     

Development of an adaptive radial basis function neural network estimator-based continuous sliding mode control for uncertain nonlinear systems

In this paper an adaptive neural network (NN)-based nonlinear controller is proposed for trajectory tracking of uncertain nonlinear systems. The adopted control algorithm combines a continuous second-order sliding mode control (CSOSMC), the radial basis function neural network (RBFNN) and the adaptive control methodology. First, a second-order sliding mode control scheme (SOSMC), which is published recently in literature for linear uncertain systems, is extended for nonlinear uncertain systems. Second, an adaptive radial basis function neural network estimator-based continuous second order sliding mode control algorithm (CSOSMC-ANNE) is adopted. In CSOSMC-ANNE control methodology, a radial basis function neural network with adaptive parameters is exploited to approximate the unknown system parameters and improve performance against perturbations. Also, the discontinuous switching control of SOSMC is supplanted with a smooth continuous control action to completely eliminate the chattering phenomenon. The convergence and global stability of the closed-loop system are proved using Lyapunov stability method. Numerical computer simulations, with dynamical model of the nonlinear inverted pendulum system, are presented to demonstrate the effectiveness and advantages of the presented control scheme.     

大时滞过程新型模糊控制策略研究进展

工业控制过程中普遍存在着大惯性、纯滞后对象的控制问题,而大时滞过程的控制依然是控制领域中的研究热点.该文就大时滞系统的各种改进型模糊控制策略的研究及其应用进行综述,并指出模糊控制与传统滞后控制方法的结合对大时滞过程的控制是有效的,可望在工业实践中得到广泛应用.     

Robust decentralized hybrid adaptive output feedback fuzzy control for a class of large-scale MIMO nonlinear systems and its application to AHS

This paper presents a novel observer-based decentralized hybrid adaptive fuzzy control scheme for a class of large-scale continuous-time multiple-input multiple-output (MIMO) uncertain nonlinear systems whose state variables are unmeasurable. The scheme integrates fuzzy logic systems, state observers, and strictly positive real conditions to deal with three issues in the control of a large-scale MIMO uncertain nonlinear system: algorithm design, controller singularity, and transient response. Then, the design of the hybrid adaptive fuzzy controller is extended to address a general large-scale uncertain nonlinear system. It is shown that the resultant closed-loop large-scale system keeps asymptotically stable and the tracking error converges to zero. The better characteristics of our scheme are demonstrated by simulations.