含控制时滞的海洋平台前馈反馈最优跟踪控制

通过引入状态变换,将含控制时滞的海洋平台系统转化为无时滞系统.然后,通过引入渐近稳定的期望系统,基于波浪力线性外系统近似模型,给出了海洋平台系统基于二次型性能指标泛函的前馈反馈最优跟踪控制器设计方法及其控制器的存在唯一性条件.控制器的前馈增益矩阵和反馈增益矩阵可分别经由求解代数Riccati方程和Sylvester方程得到.仿真算例表明了方法的有效性,且在减小平台的振动幅值和控制力方面,前馈反馈最优跟踪控制方法优于前馈反馈最优控制方法.     

基于神经网络的SPC/EPC整合过程监测方法研究

为解决统计过程控制(SPC)/工程过程调整(EPC)整合引起的传统SPC控制图监测异常扰动效率低的问题,提出了采用神经网络技术监测SPC/EPC整合过程的策略,并对神经网络模型结构和参数设置进行分析,构建过程输入、过程输出及两者的协方差为输入参数,异常扰动发生与否为输出参数的3层神经网络模型。为验证该方法的性能,进行了大量的比较实验:即对相同的样本,分别采用Shewhar图、CUSUM图和上述神经网络模型进行监测。实验结果表明:神经网络模型能准确监测幅度大于2的阶跃扰动和大于2的过程漂移,平均运行步长(ARL)为1;传统SPC监测技术只能较准确地(监测率大于90%)监测幅度大于5的阶跃扰动和大于2的过程漂移,ARL大于2。与传统监测方法相比,该方法能快速有效地监测异常扰动的发生。     

Deriving control parameter settings from process models to control capsule fillers integrated into continuous manufacturing

The aim of this work was to investigate the mean fill weight control of a continuous capsule-filling process, whether it is possible to derive controller settings from an appendant process model. To that end, a system composed out of fully automated capsule filler and an online gravimetric scale was used to control the filled weight. This setup allows to examine challenges associated with continuous manufacturing processes, such as variations in the amount of active pharmaceutical ingredient (API) in the mixture due to fluctuations of the feeders or due to altered excipient batch qualities. Two types of controllers were investigated: a feedback control and a combination of feedback and feedforward control. Although both of those are common in the industry, determining the optimal parameter settings remains an issue. In this study, we developed a method to derive the control parameters based on process models in order to obtain optimal control for each filled product. Determined via rapid automated process development (RAPD), this method is an effective and fast way of determining control parameters. The method allowed us to optimize the weight control for three pharmaceutical excipients. By conducting experiments, we verified the feasibility of the proposed method and studied the dynamics of the controlled system. Our work provides important basic data on how capsule filler can be implemented into continuous manufacturing systems.     

基于动态输出反馈的半车主动悬架系统鲁棒控制

研究了半车主动悬架系统基于输出反馈的干扰抑制鲁棒控制问题。首先建立了半车主动悬架系统的动力学模型,然后针对车体位置和速度、车身俯仰角度和角速度、前后车轮位置和速度无传感器测量情况下,系统中还存在非线性和外界扰动的现象,提出了一种动态输出反馈鲁棒干扰抑制控制策略。理论推导和仿真结果都证明了所设计控制器的正确性和有效性,通过和传统的PID控制算法相对比,进一步说明所设计的控制器能提高汽车的行驶平顺性和操作稳定性。     

A run-to-run control algorithm based on timely and delayed mixed-resolution information

In certain run-to-run (R2R) processes, timely accurate measurements are difficult to obtain due to slow laboratory measurement operations. Instead, only low-resolution categorical observations are observed online for important quality variables; continuous measurements for the same variables are provided after a specific amount of delay. Currently, most conventional R2R controllers cannot be applied if no continuous observations are available. It is therefore important to develop online algorithms for R2R process control based on mixed-resolution information that is partially timely and partially delayed. In this study, we take the lapping process in semiconductor manufacturing as an example and propose parameter estimation models with these mixed-resolution data for processes with the first-order autoregressive, AR(1), disturbance series. We also derive control strategies to generate recipes between production runs for better process control. The computational results of a performance evaluation show that the control performance of the proposed method is competitive compared to existing methods that are based on accurate measurements.     

柔性关节空间机械臂奇异摄动自抗扰控制仿真研究

针对不同重力环境条件下考虑摩擦、关节刚度非线性与外扰影响的柔性关节空间机械臂的控制问题,提出了一种基于奇异摄动理论的自抗扰控制方法。首先建立了柔性关节空间机械臂在地面重力和空间微重力环境下的动力学模型;然后采用奇异摄动法将系统模型分为快变子系统和慢变子系统,针对快变子系统设计速度反馈控制律来抑制柔性关节的振动,针对慢变子系统设计加入前馈补偿的自抗扰控制器(ADRC)来抵抗系统的内外扰动,并对系统进行了稳定性分析;最后对设计的控制器进行了仿真验证与对比研究。仿真结果表明,采用该方法,在不同重力环境下柔性关节空间机械臂均能实现很好的轨迹跟踪和抖振抑制,且能有效抵抗内外扰动,系统具有鲁棒性。     

Robustness properties of Cuscore statistics for monitoring a nonstationary system

We investigate the performance of cumulative score (Cuscore) charts in monitoring a nonstationary process subject to minimum mean‐squared error (MMSE) feedback control. Specifically, we have previously designed Cuscore statistics to discover spike or step signals hidden in a nonstationary noise disturbance for feedback‐controlled processes. Here, we study the properties of the proposed policies in terms of their robustness to process model misspecification, to deviations from assumed values for their parameters, to model misspecification for the disturbance as well as to model misspecification for the signal. We found that, in general, the Cuscore charts are fairly robust to process and signal model misspecification. However, they are less robust to departures from its true parameter values. We present a numerical example to demonstrate the importance of understanding the Cuscore's robustness as well as its construction and application. Copyright © 2008 John Wiley & Sons, Ltd.     

Nonlinear control of a rigid rotor magnetic bearing system:modeling and simulation with full state feedback

Control strategies for magnetic bearings often focus on linear optimal control techniques. While these methods afford many advantages, the literature is conspicuously sparse with regard to attempts at nonlinear control. Here, we treat the equations of motion of a rigid, horizontal rotor magnetic bearing system. Through feedback linearization and sliding mode control techniques, we formulate a nonlinear control law which maintains the shaft centered in the bearings. This system is then simulated to demonstrate disturbance rejection properties and its robustness to parameter uncertainty and unmodelled dynamics     

A self‐tuning run‐by‐run process controller for processes subject to random disturbances

Abstract

In this paper a self‐tuning run‐by‐run process controller is presented. The controller has the capability of choosing a control parameter dynamically in response to the underlying process disturbances. There are two modules in this controller: a self‐tuning loop trigger module and a run‐by‐run feedback control module. In the self‐tuning loop trigger module, two EWMA control charts are used sequentially to determine if there is a large or medium shift in the process output and to trigger a new self‐tuning loop accordingly. In the run‐by‐run feedback control module, the control parameter and control model are re‐tuned sequentially and a new process recipe is generated, on a run‐by‐run basis, to compensate for the process output's deviation from the target. Monte Carlo simulation results show that the self‐tuning run‐by‐run process controller is superior to the current run‐by‐run process controller with a fixed control parameter.     

气动主-被动一体化隔振器控制策略分析

首先分析气动主-被动一体化隔振器采用负载加速度、位移、气腔压力反馈和基座加速度前馈时的隔振性能。分析表明负载加速度反馈能增大系统阻尼比．衰减谐振峰；负载绝对位移反馈能降低系统低频传递率，相对位移反馈对系统特性没有改进；系统中没有机械弹簧时．气腔压力反馈的作用与加速度反馈类似，有机械弹簧时，压力反馈不会有明显效果；在负载加速度反馈的基础上引入基座加速度前馈能进一步改进隔振性能。然后应用负载加速度反馈和基座加速度前馈对隔振器进行了主动隔振实验，实验结果与分析结果相符。也将自适应滤波算法应用于隔振器的主动控制，取得了更好的振动抑制效果。     

Dynamic analysis of an inventory and order based production control system

In an inventory and order based production control system (IOBPCS), there are three fundamental system parameters. One of these, the production delay time, is beyond the control of the IOBPCS designer. Indeed, the production delay may be highly variable with time due to a variety of problems commonly found in manufacturing industry. This uncertainty must be countered by the proper use of a feedback loop which detects and operates on inventory deviations. The IOBPCS designer is thus left with the forward path demand averaging time and feedback path gain to adjust, as best he can.

This paper studies the ability of the IOBPCS to recover from shock demands, and to protect the manufacturing process from random variations in consumption. It is shown that the feedback path is of fundamental importance in good control, and that adequate performance cannot be obtained by feedforward alone. Dynamic recovery is examined graphically by separately identifying the feedforward and feedback components. Random disturbance rejection is studied via the noise bandwidth concept. Finally, performance optimization is undertaken using coefficient plane models related to ‘standard forms’ and hardware systems. One good compromise design achieved has the time-to-adjust inventory, demand averaging time, and production delay time all of comparable magnitude.     

旋转偏心质量块式消振电力作动器建模与控制EI北大核心CSCD

直升机等非固定翼飞行器在飞行状态时由桨叶旋转所产生的周期性低频振动会通过刚性机体传递至驾驶舱、航空发动机以及起落架等部位,会造成机体的持续振动,严重时会影响驾驶员的生命安全。提出了旋转偏心质量块式消振电力作动器,并开展了控制方法研究。从理论上推导了旋转偏心质量块式消振电力作动器的输出力模型以及负载转矩模型;提出基于双电机并行独立控制的电力作动器输出力伺服控制策略,在复频域进行了稳定性分析,并针对正弦波非线性负载扰动带来的转矩脉动问题,对双电机并行独立控制策略展开了优化设计,通过负载前馈控制使系统具备良好的鲁棒性和抗干扰性;研制了重量为14 kg的实验样机并完成了优化控制策略前后电力作动器稳态、动态性能的对比验证实验。结果表明,优化控制策略下的作动器输出力动稳态性能满足各项技术指标要求。     

A cautious minimum variance controller with ARIMA disturbances

This article investigates a Cautious Minimum Variance (CMV) control approach for controlling industrial process variability when the model parameters are estimated from data and subject to uncertainty. CMV control has a number of advantages over traditional robust control methods. It incorporates probabilistic, as opposed to deterministic, measures of parameter uncertainty, which are more consistent with the statistical methods typically used to estimate industrial process models. CMV control is also more consistent with the objective of minimizing process variability, since parameter uncertainty is treated simply as an additional source of variation. CMV results have previously been derived for the case where the process disturbance follows a first-order integrated moving average model. This work extends the results to autoregressive moving average and autoregressive integrated moving average disturbances.     

Adaptive feedforward cancellation of sinusoidal disturbances in superconducting RF cavities

A control method, known as adaptive feedforward cancellation (AFC), is applied to damp sinusoidal disturbances due to microphonics in superconducting radio frequency (SRF) cavities. AFC provides a method for damping internal and external sinusoidal disturbances with known frequencies. It is preferred over other schemes because it uses rudimentary information about the frequency response at the disturbance frequencies, without the necessity for an analytic model (transfer function) of the system. It estimates the magnitude and phase of the sinusoidal disturbance inputs and generates a control signal to cancel their effect. AFC, along with a frequency estimation process, is shown to be very successful in the cancellation of sinusoidal signals from different sources. The results of this research may significantly reduce the power requirements and increase the stability for lightly loaded continuous-wave SRF systems.     

Relationships Among Control Charts Used with Feedback Control

Feedback control is common in modern manufacturing processes and there is a need to combine statistical process control in such systems. Typical types of assignable causes are described and fault signatures are calculated. A fault signature can be attenuated by the controller and an implicit confounding among faults of different types is discussed. Furthermore, the relationships between various control statistics are developed. Control charts have been proposed previously for deviations from target and for control adjustments. We describe why one or the other can be effective in some cases, but that neither directly incorporates the magnitude (or signature) of an assignable cause. Various disturbance models and control schemes, both optimal and non‐optimal, are included in a mathematically simple model that obtains results through properties of linear filters. We provide analytical results for a widely‐used model of feedback control. Copyright © 2006 John Wiley & Sons, Ltd.     

Integrating statistical process monitoring with feedforward control

Feedforward control is a particular form of engineering process control. If a known input variable z_t can be measured and appropriate relationships built between the input variable, a compensatory variable x_t, and the desired output y_t, then a feedforward control system can be developed. Using feedforward control, we show under both sudden jump shifts and trends in the mean of the input and compensatory variables that the use of statistical process monitoring tools, such as the exponentially‐weighted moving average and the cumulative sum (CUSUM), significantly reduces variability in both the output variable and the controller relative to the use of feedforward control alone. Copyright © 2000 John Wiley & Sons, Ltd.     

Algorithmic Statistical Process Control: Concepts and an Application

The goal of algorithmic statistical process control is to reduce predictable quality variations using feedback and feedforward techniques and then monitor the complete system to detect and remove unexpected root causes of variation. This methodology seeks to exploit the strengths of both automatic control and statistical process control (SPC), two fields that have developed in relative isolation from one another. Recent experience with the control and monitoring of intrinsic viscosity from a particular General Electric polymerization process has led to a better understanding of how SPC and feedback control can be united into a single system. Building on past work by MacGregor, Box, Astrom, and others, the article covers the application from statistical identification and modeling to implementing feedback control and final SPC monitoring. Operational and technical issues that arose are examined, and a general approach is outlined.     

非线性系统高阶微分反馈控制

提出了不依赖系统模型的高阶微分反馈控制思想，控制目标是系统输出及其微分和高阶微分逼近设定输入及其微分和高阶微分，极大地提高了对控制品质要求。基于这种思想设计了能高品质地提取量测信号的微分和高阶微分的高阶微分器（HOD, highorder differentiator），该HOD参数少，容易调节，并给出其稳定性、收敛性和滤波特性的证明；另外，对带有未知扰动、模型未知的非线性SISO和MIMO系统分别设计了基于HOD的高阶微分反馈自适应控制器(HODFC, high order differentials feedback adaptive controller)，给出了闭环系统稳定性和鲁棒性分析，并且实现了线性化解耦控制。     

地震模拟振动台三参量控制参数整定技术的研究

对地震模拟振动台三参量控制及其参数整定技术进行了研究,提出了一种快速三参量控制参数整定方法。通过对三参量控制算法的研究,确定三参量控制器中三参量反馈及前馈环节中各个参数的数学表达式,从而完成三参量控制器中控制参数的整定,极大地提高了地震模拟振动台三参量控制参数整定的效率。最后,通过仿真和现场试验的方法,将传统三参量控制参数整定方法与快速三参量控制参数整定方法进行对比试验,进一步证明了快速三参量控制参数整定方法的可行性和高效性。     

基于滑模输出反馈与输入成形控制相结合的挠性航天器主动振动抑制方法

针对挠性航天器大角度姿态机动的振动抑制问题，提出了一种基于输出反馈滑模控制和输入成形振动抑制方法相结合的主动振动控制策略。输入形成器作为前馈控制器作用在反馈回路的前相通道，通过改变输入命令的作用形式，在保证参考模型（标称对象）完成指定的姿态机动的同时抑制掉对系统影响较大的挠性结构的振动；而对于闭环控制回路，考虑挠性结构模态不可测、模型参数具有不匹配不确定性以及外干扰力矩的作用，在输出反馈滑模控制的基础上，给出了仅利用输出信息的滑模控制器设计方法，保证跟踪参考模型的输出以获得要求的闭环系统的性能。将该方法应用于单轴挠性航天器的大角度rest—to—rest（静止到静止）姿态机动控制进行了仿真研究，结果表明，所提出的方法是可行而有效的。