Design and analysis of a fuzzy logic controller

The fuzzy logic controller (FLC) presented by Siler and Ying (1989) is discussed here and is proved to be equivalent to a non-fuzzy, nonlinear, proportional-integral (PI) controller. Some characteristic properties of this fuzzy logic controller are then investigated. The achievable performance of such a specific fuzzy controller is examined and found to be not necessarily better than that of the conventional, linear, non-fuzzy PI controller. Various extended designs of the basic FLC, including the FLC with dual control laws and the three-piece FLC, are then presented to enhance control performance. These extensions can provide servo-control performance. These extensions can provide servo-control performance superior to that of the basic FLC design, as illustrated by simulation results. Finally a highly nonlinear neutralization process is advanced to demonstrate the applicability of the various FLCs to industrial process control.     

Design and analysis of direct-action CMAC PID controller

This paper is to propose a direct-action (DA) cerebellar model articulation controller (CMAC) proportional-integral-derivative (PID) controller. The proposed controller, termed the DAC-PID controller, can generate four simple types of the nonlinear functions and then determine a control effort from those functions to control the process. In addition, the real-coded genetic algorithm is used to tune the parameters of the DAC-PID controller such that we can optimize those parameters. The performance of the proposed controller is also discussed in the sense of quantitative analysis. Simulation results demonstrate that the DAC-PID controller is superior to the conventional PID controller tuned by Ziegler–Nichols method and, moreover, as better as the optimal PID controller and the optimal fuzzy-PID controller.     

Sliding controller for damping inter-area power oscillations

In this paper, a sliding control algorithm design is considered for damping the inter-area power transmission oscillations. The control algorithm is intended for the static Var compensators (SVC) to supply reactive power to the power transmission system, in order to stabilize the system in the event of faults. The controller is capable of achieving full utilization of the SVC and is insensitive to parameter variations and modeling errors. The simulation results show the effectiveness of the sliding controller in damping the inter-area power oscillations, and in enhancing the stability as well as loadability of the transmission systems.     

卫星初始速度阻尼智能控制器设计

针对卫星入轨后的初始速率阻尼问题,提出一种基于人脑中情绪学习模型的在线自主自适应控制器。该控制器模拟人脑对感官输入和情绪刺激的处理过程,自主选择适当的控制信号,完成控制任务。设计了基于PID控制和PWPF调制的人脑情绪学习模型智能控制器用以完成卫星初始速率阻尼控制。仿真结果表明,该智能控制器对于卫星转动惯量的不确定性具有较强的鲁棒性,在线学习能力使得智能控制器的性能明显优于PID控制器。     

一种新型附加学习控制器及电力系统应用实例

维纳的《控制论》和钱学森的《工程控制论》共同奠定了经典控制理论的基础.在此基础之上,现代控制理论在性能优化和处理不确定性等方面对经典控制理论作了进一步的发展.本文提出一种融合经典控制与现代控制的控制方法,将属于现代控制的近似动态规划学习控制器以并联的方式附加到经典控制器上,从而形成一类新型附加学习控制器.该控制器采用基于策略迭代近似动态规划的训练算法和基于最小二乘的代价函数逼近算法,从而具有高策略搜索效率和高样本利用效率,其中动作依赖代价函数的引入使得在线学习不依赖系统模型.总之,所提附加学习控制器一方面融合了已有经典控制器的先验知识,另一方面为已有经典控制器提供了可设计的目标函数和自趋优机制.论文进一步从理论上严格证明了所提附加学习控制方法的稳定性和收敛性.针对双馈风电场暂态无功控制问题的仿真研究验证了所提附加学习控制器的正确性和方法的有效性.     

Variable structure controller design for spacecraft nutation damping

Variable structure systems theory is used to design an automatic controller for active nutation damping in momentum biased stabilized spacecraft. Robust feedback stabilization of roll and yaw angular dynamics is achieved with prescribed qualitative characteristics which are totally independent of the spacecraft defining parameters.     

Design and analysis of gain-scheduled control using local controller networks

This paper describes a nonlinear control structure known as a local controller network. The structure consists of a weighted combination of a number of individual controllers, each of which is valid locally in the state space of the plant. Local controller designs are based upon local models valid in operating regimes which do not necessarily contain any physical equilibria. Consequently, the transient performance can be improved. Some 'scheduling' variables determine the current operating regime, and a validity function is assigned to each local controller. A 'feedforward' component may be used in each local controller in order to compensate directly for the operating-point-dependent model offsets. The application of the local controller network approach to a nonlinear control problem, that of longitudinal vehicle dynamics control, is described. A stability analysis for the discrete-time local controller network is given in this paper and the results are compared with known theoretical guidelines for related control approaches such as gain scheduling and feedback linearization.     

Design and stability analysis of a variable structure adaptive backstepping controller

This paper presents the design and stability analysis of a Variable Structure Adaptive Backstepping Controller (VS‐ABC) for linear plants with relative degree one, using only input/output measurements. Instead of traditional integral adaptive laws for estimating the plant parameters, switching laws are proposed to increase robustness to parametric uncertainties and disturbances, as well as to improve transient response. Moreover, the controller design is more intuitive when compared with the original adaptive backstepping controller, since the relay amplitudes are related to the plant nominal parameters and their respective uncertainties. Simplified algorithm versions are also presented, named Compact and Relay VS‐ABC, which reduce the practical implementation complexity, and encourage applications in industrial environments. Copyright © 2011 John Wiley and Sons Asia Pte Ltd and Chinese Automatic Control Society     

Design and analysis of a self-tuning feedback controller for the Internet

Active queue management (AQM) is an effective method used in Internet routers for congestion avoidance, and to achieve a tradeoff between link utilization and delay. The de facto standard, the random early detection (RED) AQM scheme, and most of its variants use average queue length as a congestion indicator to trigger packet dropping. This paper proposes a novel packet dropping scheme, called self-tuning proportional and integral RED (SPI-RED), as an extension of RED. SPI-RED is based on a self-tuning proportional and Integral feedback controller, which considers not only the average queue length at the current time point, but also the past queue lengths during a round-trip time to smooth the impact caused by short-lived traffic dynamics. Furthermore, we give theoretical analysis of the system stability and give guidelines for selection of feedback gains for the TCP/RED system to stabilize the average queue length at a desirable level. The proposed method can also be applied to the other variants of RED. Extensive simulations have been conducted with ns2. The simulation results have demonstrated that the proposed SPI-RED algorithm outperforms the existing AQM schemes in terms of drop probability and stability.     

基于车流信息的智能巡航控制器的设计分析

设计一个模拟人类驾驶行为的智能巡航控制器。在分析现有巡航控制的基础上,提出利用车流前后车辆的相对速度和间距信息的智能巡航控制算法来选择正确的控制行为,从而平顺跟车行为,使车辆能保持由驾驶员指定的理想跟车距离。仿真结果显示,在此智能巡航控制下能保证车辆和车队在前、后两个方向上的稳定性。     

Design and analysis of optimal controller for fuzzy systems with input constraint

In this paper, we present a design method of the optimal and robust controller subject to the constraint on control inputs for continuous-time Takagi-Sugeno (TS) fuzzy systems. In order to establish this design method, we consider an optimal and robust control problem for nonlinear dynamic systems. For this problem, we present an analytic way which can provide the optimal controller for nonlinear dynamic systems by the dynamic programming approach and the inverse optimal approach. Moreover, we analyze the robustness property of the proposed optimal controller with respect to a class of input uncertainties by the passivity approach. Then, based on the theoretical results presented in this paper, we formulate the design problem of the optimal and robust controller with input constraint for continuous-time TS fuzzy systems as the semidefinite programming problem, and find the controller by solving it. The usefulness of the proposed approach is illustrated by considering the three-axis attitude stabilization problem of rigid spacecraft.     

Design of a multilevel fuzzy controller for nonlinear systems and stability analysis

In this paper, a multilevel fuzzy control (MLFC) system is developed and implemented to deal with the real-world nonlinear plants with intrinsic uncertainties and time-varying parameters. The proposed fuzzy control strategy has a hierarchical structure with an adaptation mechanism embedded in the lower level to tune the output membership functions (MFs) of the first layer fuzzy controller and can be used to control a system with an input-output monotonic relationship or a piecewise monotonic relationship. The stability of the closed-loop system under the proposed MLFC is theoretically proven. Simulations are carried out by applying the proposed multilevel fuzzy control (MLFC) to a uncertain nonlinear plants, and it is shown that much better system performances are achieved compared with conventional fuzzy logic controllers (FLC), even in presence of disturbance and noise.     

Design sensitivity analysis of acoustical damping and its application to design of musical bells

Damping characteristics of a musical bell plays an important role in characterizing the musical sound. The total damping consists of acoustical damping and internal damping. Acoustical damping depends upon resonating frequencies and vibration patterns while internal damping is a material property. The acoustical damping of a vibrating structure is formulated via boundary element method and finite element method using eigenmode decomposition. The design sensitivity of acoustical damping is derived using an adjoint variable method of the eigenvalue problem. Design optimization of a musical bell is then performed in terms of acoustical parameters. The goal of the optimization problem is to design a harmonically tuned bell with given acoustical damping values. The proposed automated design process integrates finite element analysis, boundary element analysis, design sensitivity analysis, mode-tracking algorithm and optimization module, seamlessly. It is demonstrated by numerical examples to show practical applications.     

附加阻尼控制SVC在双馈型风电场中的应用研究

将附加阻尼控制SVC应用于兆瓦级双馈型风电场并网系统,在此基础上研究了系统的暂态过程.首先建立了双馈风电机组的动态模型,水轮发电机组以及附加阻尼控制SVC的数学模型,然后仿真研究了双馈型风电场并网以后对区域系统暂态过程的影响,对比分析了风电场接入和故障情况下采用普通SVC和附加阻尼控制SVC的作用和效果,仿真结果验证了建立模型和采取方法的正确性和有效性.     

不确定隶属函数T-S模糊控制器设计与稳定分析

针对许多非线性系统存在的结构不确定和难以用精确数学模型表达等问题,在研究基本Takagi-Sugeno(T-S)模糊模型的基础上,通过增加一个隶属函数自由变量,利用线性矩阵不等式(LMI)设计了一个使得闭环系统渐进稳定的状态反馈控制器,并给出稳定条件.所得到的条件充分利用了前件变量隶属函数的结构信息和后件局部子系统之间的相互关系,降低了常规T-S模糊系统的稳定性条件的保守性和求解难度.通过仿真实例验证了该方法的可行性和有效性.     

液压控制器的设计与实现

液压控制器是一种具有控制精度高、响应速度快和输出功率大特点的控制元件,具有极高的应用价值,可广泛应用到诸多领域中。当前,液压控制器在具体的使用中,存在处理高速与低速设备的速度匹配问等问题,影响液压控制器的应用。故此,文章选择模块化设计方式、高速处理速度DSP为核心控制芯片、丰富通讯接口、4轴驱动能力等技术措施,进一步完成对液压控制器的优化设计,并借助仿真模拟,确定改进后的液压控制器具有高性能、高响应速度等特点,可有效保障相关设备的稳定运行,实现行业的发展与进步。     

交通信号自适应模糊控制器的设计及稳定性分析

针对城市交通路口的信号控制,提出一种自适应模糊控制器,并对其稳定性进行分析.通过控制器给出路口实时信号配时,根据红灯相位的等候车辆平均损失和绿灯相位释放车辆的平均增益,给出了模糊控制器的自适应算法,以实时修正其模糊规则.在自适应模糊控制器的稳定性分析中,采用模糊控制系统闭环模型的模糊关系矩阵,证明在路口车辆随机产生的情况下,模糊控制系统是稳定的.仿真结果表明,自适应模糊控制器比全感应控制器、简单模糊控制器更能适应路口交通流的变化,极大地改善了系统性能.     

Design of model-following servo controller

A servo controller is designed so that the step response of the plant is as close as possible to that of a model system while the output regulation condition is satisfied. The controller is named "the model-following servo" and its control law is determined by optimization. The associated algorithm is presented. An example is included to illustrate the procedure.     

嵌入式控制器开关设计方案

嵌入式控制器常有两种开关功能需求:希望开关键响应按键操作迟钝些,即按下几秒后才认为按键操作有效;还有种需求是在设备关闭过程做一定的判断或处理,这类关机操作一般使用软件控制实现关机.本文针对嵌入式控制器开关机功能的两种需求给出了整套较为实用的方案,即:实现单键长按开关功能、程控关机功能接口.     

基于遗传算法的切换控制器设计与优化

利用遗传算法研究了一类切换规则只由状态决定的切换系统的控制器优化设计问题.首先由线性矩阵不等式(LMI)来设计切换控制器,然后应用遗传算法来对切换规则进行优化.优化后的切换规则不仅可保证闭环系统渐近稳定,而且具有良好的动态性能.将本文提出的方法应用在小车倒立摆控制系统上,仿真结果表明了本文设计方法的有效性.