基于多环QFT的飞行仿真转台鲁棒控制

阐述了定量反馈理论(QFT)的基本原理及设计方法,并给出了某型飞行仿真转台的QFT控制器设计实例。为了有效地抑制高频测量噪声对系统的干扰,以及避免系统的高频不确定性,在单环QFT控制的基础上,引入了基于多环QFT的鲁棒控制。理论分析和仿真实验表明,这种多环QFT控制可以明显地缩减控制器的带宽,使系统具有很强的抗高频测量噪声的性能,达到了理想的控制效果。该方法在转台的控制上取得了成功的应用,具有广泛的应用价值。     

MIMO系统预测控制及其Matlab与VC仿真实现

本文对一个多入多出耦合系统设计了一种基于隐式算法的广义预测控制器(GPC),此隐式算法利用与基于脉冲模型的预测控制(DMC)算法的等价性化简,避免求解Diophantine方程。同时对此多入多出系统设计了DMC控制器,并对二种算法和控制效果进行了比较。本文用Matlab编程实现两种控制算法,用VC++设计界面,在VC中调用M函数的动态链接库DLL实现Matlab和VC的混合编程。对此被控MIMO系统,最终即可通过在VC界面上实现控制方式和控制输出的设定得到控制输入输出的仿真图。此程序可以脱离Matlab环境运行。     

基于QFT和ZPETC的高精度鲁棒跟踪控制器设计

阐述了定量反馈理论(QFT)和零相差跟踪控制器(ZOETC)的基本原理及设计方法，并给出了设计实例。在QFT和ZPETC的基础上，提出了一种是实现高精度鲁棒跟踪控制的方案，采用QFT控制保证系统的鲁棒性，通过ZPETC提高系统的跟踪精度。仿真表明，这种方法实现了QFT和ZPETC的完美结合，很适合高精度跟踪系统的鲁棒控制。     

一种基于QFT的锅炉水位鲁棒控制及分析

在工业实际应用中,锅炉汽包水位在系统动态特性发生较大变化并且受到各种干扰因素影响时,模型的参数将发生变化,成为一个不确定系统.基于此种情况,本文应用定量反馈理论(QFT),提出了基于QFT的锅炉水位鲁棒控制方案,即内回路采用小积分常数比例积分控制器快速消除给水扰动,外回路应用QFT理论设计出主控制器并对主控制器的PID参数进行了整定,以保证水位无静态偏差,仿真结果表明,此种控制方法能够达到比较满意的效果.     

自适应的时变比例增益的预测PID控制器

为了利用PID控制获得先进的控制性能,将广义预测控制(GPC)用于PID参数的实时优化,在此基础上提出了一种新的基于GPC的自适应PID控制器的设计方法.该PID控制器具有时变的比例增益,并且PID控制器的设计利用了GPC的未来参考输入.因此,GPC控制律能由设计的PID控制器精确实现.为使GPC控制器稳定地获得比例增益,采用了基于互质因子分解扩展的强稳定GPC,独立于利用标准GPC设计的闭环系统而重新设计GPC控制器,保证了闭环系统的稳定性.此外,利用递推最小二乘法对系统进行在线辨识,修正模型参数,增强了系统的抗扰性.以一阶时滞非最小相位系统为被控对象,在Matlab中对该设计方法进行了仿真,仿真结果验证了该方法的有效性.     

基于GPC算法的网络控制系统研究

针对具有随机时延的一类网络控制系统(NCS),文章设计了一种基于时延补偿和广义预测控制(GPC)算法的控制器。该控制器根据数据包的时间戳计算传感器-控制器时延,通过时延补偿得到被控对象当前的状态和输出,采用GPC算法计算控制量。仿真结果证实了该控制器的有效性。     

磨矿过程磨机负荷的智能监测与控制

磨机过负荷是磨矿过程的常见故障工况, 如果不及时、准确处理, 就会造成磨矿产品质量变坏甚至磨矿生产的停顿. 采用规则推理(RBR)和统计过程控制(SPC)技术, 提出了由SPC机制、过负荷监测模块和监督控制器构成的磨机负荷智能监测与控制方法. 该方法通过对磨机过负荷的智能监测与诊断, 由监督控制器自动修改控制回路的设定值, 通过控制回路的输出跟踪修改后的设定值, 使磨机负荷逐渐远离过负荷状态. 工业应用表明, 该方法能够实现磨矿生产的安全、稳定和连续运行.     

基于Linux和S3C2440的GPC控制器设计

为克服网络控制系统中时延对系统性能的影响,提出了一种基于嵌入式Linux的广义预测控制器（GPC）的设计方案。该方案构建了以ARM9处理器S3C2440A为核心、运行Linux操作系统的嵌入式控制器平台,并通过Boa Web Server实现使用Browser/Server对控制器进行远程访问和参数调整。同时针对网络延迟采用GPC算法,对控制系统的时延进行软件补偿,以实现对被控对象的实时控制。     

基于定量反馈理论的气动调节阀控制系统设计

为了使气动调节阀控制系统满足工业过程对于模型不确定性的鲁棒性要求,设计了1种基于定量反馈理论(QFT)的气动调节阀控制系统。基于QFT的控制器是1种二自由度控制器结构,由前置滤波器和反馈控制器组成。QFT对于控制对象的不确定性具有很强的鲁棒性,能够较好地避免气动调节阀控制系统在工业过程中受到的干扰和模型不确定性影响。通过对气动调节阀控制系统进行仿真分析,验证了基于QFT的控制方法能够较好地避免该系统的不确定性,使得该系统具有较强的鲁棒性,满足相应的性能指标要求。与传统基于常规比例积分微分(PID)控制方法的气动调节阀控制系统相比,基于QFT控制方法的气动调节阀控制系统更加适用于工业过程。     

QFT与神经网络并行控制研究

阐述了定量反馈理论(Quantitative Feedback Theory，简称QFT)的基本原理及设计步骤，并给出了设计实例。在QFT的基础上，提出了一种QFT和神经网络并行控制的方案，以QFT为主控制器，神经网络进行动态误差补偿。QFT控制能克服对象的参数不确定性，保障系统的鲁棒性；神经网络可以进一步提高系统的跟踪精度。仿真表明，这种方法实现了QFT控制和神经网络控制的完美结合，很适合高精度伺服系统的鲁棒控制。     

基于Matlab语言定量反馈控制器的分析与设计

对定量反馈理论（QFT）的基本原理进行了介绍和利用Matlab语言工具箱进行设计的基本方法，Matlab通用QFT工具箱为用户进行QFT控制器的设计提供了有利的工具，文章就以典型二阶系统为例进行QFT控制器的设计，仿真的结果表明定量反馈理论在不确定系统设计中有着经典控制理论无法替代的性能。     

Self-tuning of quantitative feedback theory for force control of an electro-hydraulic test machine

The aim of this paper is to design and fabricate an electro-hydraulic test machine (EHTM) for conducting performance and stability test of force and/or position control in the bench system and to propose a robust adaptive controller—the self-tuning quantitative feedback theory (STQFT)—in order to improve the force control performance of electro-hydraulic actuators (EHAs). By using the gradient descent method to adjust the QFT parameters, the novel STQFT controller is able to adapt to a wide range of working conditions. Experiments were carried out to evaluate the effectiveness of the proposed control method applied to the EHTM.     

在GIMC结构下基于定量反馈理论的连续广义预测鲁棒稳定控制

The continuous-time generalized predictive control (CGPC) and the quantitative feedback theory (QFT) are used together to control the plant with high uncertainty. QFT conquers the plant uncertainty and stabilizes the system in the inner loop without affecting the nominal performance based on the generalized internal model control (GIMC) structure. CGPC is used to obtain the necessary control performance in the outer loop. According to several given sufficient conditions, the available tuning parameters of CGPC are selected to make the system robustly stable. Finally, an example is given to show how to use this technique; and it is shown that this combined approach gets better performance than if only one of them is used.     

定量反馈理论发展综述

定量反馈理论是一种基于频域的鲁棒控制理论,可以用于具有高度不确定性的单变量线性/非线性系统、多变量线性/非线性系统控制器设计.本文概述了定量反馈理论的基本原理、设计过程以及特点.总结了近年来QFT在提高系统性能、鲁棒稳定性、自动设计以及应用等方面的最新研究进展,并且给出了一些已有的理论应用成果.最后讨论了进一步的研究方向.     

Interactive parameter space design for robust performance of MISO control systems

This paper presents a method for the design of nonconservative low-order controllers achieving robust performance in the case of multi-input single-output parallel structure plants subject to unstructured uncertainty. The first step is the analytical generation of gain-phase controller bounds, as in quantitative feedback theory (QFT). Then, to avoid the difficult step of QFT loop shaping, which often produces high-order controllers, these bounds are translated into the controller parameter space where the iterative design of low fixed order controllers takes place. This, as well as the design transparency offered by this technique, constitutes appreciable advantages over the other popular robust performance design method of /spl mu/-synthesis. Other important features are the fact that no extra conservatism is introduced by the method presented and the fact that the method is directly compatible with a sequential loop closing strategy. Finally, the direct search optimization of any additional secondary criteria is possible.     

The input amplitude saturation problem in QFT: A survey

In this work the input amplitude saturation problem is analysed in the Quantitative Feedback Theory (QFT) framework. This paper reviews previous works in the literature dealing with the input amplitude saturation problem in the presence of an uncertain plant in the frequency domain using QFT. The objective of this paper is to compare the different available approaches and summarize the design process for each case so that this paper can be used as a tutorial; there are six main approaches to this problem. Two of these approaches use the classical two degrees of freedom control scheme for QFT; in both of these, the design constraints of a linear QFT compensator are added in the loop shaping stage: they are added in the first approach to avoid excitation of the actuator saturation and in the second one to guarantee global stability. The other three techniques are considered as anti-windup (AW) approaches. Starting from a base design in QFT with two degrees of freedom, the first AW approach introduces a third degree of freedom that guarantees the stability of the system, allowing for base designs for high performance. The other two AW approaches also introduce a third degree of freedom, but they take simple stability considerations into account and focus on the performance of the system. The last solution consists of using a reference governor technique, which guarantees the computation of a reference signal for an inner control loop that is shaped using QFT in such a way that robust stability will be guaranteed. The reference governor technique is a time domain approach that implies the resolution of an optimization problem. The rest of the approaches are frequency domain techniques based on a loop shaping method in the traditional QFT sense.     

弹性飞机的QFT控制器设计

以某弹性飞机纵向模型为例,考虑模型的不确定性及外部扰动,应用定量反馈理论设计了其俯仰姿态保持系统.仿真结果表明,利用该理论方法设计的控制器能很好地抑制弹性飞机的结构弹性变形,具有良好的鲁棒性,并取得了满意的控制效果,证明了该方法在弹性飞机控制律设计中的有效性和实用性.     

Electrohydraulic force control design of a hardware-in-the-loop load emulator using a nonlinear QFT technique

This paper presents the design of a robust force control system for an electrohydraulic load emulator utilized as part of a hardware-in-the-loop flight simulation experiment. In this application, the force controlled hydraulic actuator is used to artificially recreate in-service loads upon a second hydraulic flight actuator operated in closed-loop position control. Electrohydraulic force control is more difficult than electrohydraulic position tracking because the load dynamics influence the force transfer function in a way that makes it challenging to develop an accurate force tracking system using simple feedback control. Nonlinear quantitative feedback theory (QFT) is applied in this paper to address this issue. First, an effective and robust feedback controller is designed by nonlinear QFT to desensitize the force control loop to nonlinear servovalve flow/pressure effects and typical system uncertainties. A secondary compensator is also designed within the QFT framework to extend the force tracking bandwidth with respect to the load motion. Experiments demonstrate acceptable force tracking performance within the scope of a representative flight-simulation experiment.     

Feedback design for robust tracking and robust stiffness in flight control actuators using a modified QFT technique

The problem of dynamic stiffness of hydraulic servomechanisms has often been recognized as a significant performance issue in a variety of applications, the most notable of which includes flight control actuation. When a hydraulic actuator such as this is operated in position control, an aerodynamic flutter load on the control surface manifests itself as a force disturbance on the system. Although this would appear to be a standard disturbance rejection problem, the disturbance does not enter the system as in the classical sense (i.e. at the plant output) and hence, this problem must be considered in a modified formulation. A hydraulic servomechanism is said to be 'stiff' if it exhibits acceptable rejection of force disturbances within the control bandwidth. In this paper, an approach to feedback design for robust tracking and robust disturbance rejection is developed via the quantitative feedback theory (QFT) technique. As a result, it is shown that reasonable tracking and disturbance rejection specifications can be met by means of a fixed (i.e. non-adaptive), single loop controller. The methodology employed in this development is the sensitivity-based QFT formulation. As a result, robust tracking and robust disturbance rejection specifications are mapped into equivalent bounds on the (parametrically uncertain) sensitivity function; hence, the frequency ranges in which tracking or disturbance rejection specifications dominate become immediately obvious. In this paper, a realistic non-linear differential equation model of the hydraulic servomechanism is developed, the linear parametric frequency response properties of the open loop system are analysed, and the aforementioned QFT design procedure is carried out. Analysis of the closed loop system characteristics shows that the tracking and disturbance rejection specifications are indeed met.