参数不确定网络拥塞系统的保性能控制

针对网络控制系统在建模过程中普遍存在的参数不确定性问题,在现有的网络拥塞控制模型基础上,考虑了系统具有时变参数不确定性的情况.通过对已有非线性动态TCP模型进行线性化,得到一个带有参数不确定性的线性时变系统,并且,该线性系统模型能够更精确描述原来非线性系统.对于已得到的线性系统,利用Lyapunov稳定性理论,以及结合线性矩阵不等式处理方法,给出了网络拥塞控制系统的状态反馈保性能控制器的凸的存在条件和设计方法.通过理论分析和对实例的仿真表明,同已有的方法相比,本文所设计的方法不仅可以满足给定的性能指标,还可以使系统具有较强的鲁棒性及较快的收敛性.     

矿热炉电极调节系统的双闭环自抗扰控制

对矿热炉电极系统提出了一种自抗扰控制策略的控制方法。设计了一种不依赖于对象模型的电极自抗扰控制器,并对其参数进行了整定,自抗扰控制器的扩张状态观测器可以实时观测系统状态和扩张状态,从而实现全状态反馈及系统不确定性和外扰的补偿控制。该系统与传统的单闭环恒流控制系统比较,增加了电极位置环。仿真实验表明,该控制系统不仅具有较强的鲁棒性,对内外干扰具有较强的抑制能力,更具有较优的动态性能。     

基于复合干扰观测器的轧机液压伺服位置系统终端滑模控制

针对轧机液压伺服位置系统,考虑参数不确定性、负载扰动和输入饱和非线性的影响,提出一种基于复合干扰观测器的终端滑模控制方法。将轧机液压伺服位置系统中的参数不确定性、负载扰动以及输入饱和非线性视为复合干扰,通过选用快速终端滑模干扰观测器对其进行逼近估计,并将输出的估计值引入到所设计的控制器中进行补偿。通过稳定性理论分析表明,在所设计的控制器的作用下,闭环系统全局渐趋稳定。最后,基于某650 mm可逆冷带轧机液压伺服位置系统的实际参数进行仿真研究,结果表明,所设计的控制器能够实现系统输出对期望位置的准确跟踪。     

前馈厚度控制的外部自激励定量反馈调节

分析了板材轧制过程中出口厚度变化的成因.将不确定扰动的影响归结为轧机刚度系数摄动和轧件塑性系数摄动,建立了双摄动厚度控制模型.综合考虑轧机系统的外部不确定扰动,针对轧制道次间的不确定性,在频域内将板厚信息转化为轧机系统边界性能指标,设计抑制前馈扰动的外部自激励定量反馈控制器.仿真实验表明,设计的控制器能有效抑制轧制过程中的外部扰动,具有良好的鲁棒性能,并能直观保证系统调整时的鲁棒稳定性,适于工业生产.     

关于非独立控制励磁的他励直流电动机采用双通道LQSF直流调速系统时励磁回路控制的探讨

晶闸管整流装置——直流电动机系统(简称SCR——D系统)中,采用现代控制理论设计的双通道全状态反馈直流调速系统(LQSF),可以显著提高调速系统动态性能指标:缩短恢复时间、降低动态速降、具有足够的稳定裕量和很强的鲁棒性,提高了系     

基于H_∞混合灵敏度的冷连轧机多变量解耦鲁棒控制

冷连轧过程中的厚度和张力系统具有多变量、强耦合和不确定特点,为了提高系统的控制精度和控制性能,提出了基于不变性原理解耦的H∞混合灵敏度鲁棒控制策略.首先,建立了厚度和张力系统的动态耦合模型,并应用不变性解耦原理实现了对厚度和张力系统的解耦.其次,针对系统存在的建模误差、参数摄动和外部扰动等不确定性,采用H∞混合灵敏度方法设计了鲁棒控制器来保证系统的鲁棒稳定性和鲁棒性能.仿真结果表明解耦后的厚度和张力系统可以获得更好的控制效果,验证了本算法的有效性.     

基于反馈线性化的单相电弧炉电极调节系统输出跟踪控制

讨论反馈线性化方法在单相电弧炉电极调节系统控制中的应用.在存在弧长扰动的情况下,应用基于微分几何的线性反馈方法将原非线性系统等价为完全可控的线性系统,以此设计控制器,并进行了Matlab仿真.仿真结果表明,具有跟踪精度高、反应速度快、鲁棒性强特性的反馈线性化控制方法,在单相电弧炉电极调节系统输出跟踪控制中应用后,控制效果良好.     

单机架可逆冷轧机厚度闭环控制AGC系统的改进

理论推导出BISRA AGC对于来自轧机方面的干扰不仅不能消除、而且还对其有放大作用的结论,故唐山钢铁集团有限公司冷轧薄板厂1650 mm可逆式冷轧机改进了单纯的BISRA AGC控制,采用以BISRA AGC为主、测厚仪反馈为辅的厚度闭环AGC控制系统,研究了厚度闭环AGC系统的主要问题,调节器参数的自适应控制.结果表明,控制效果良好,产品厚度偏差提高到±5μm以内.     

鞍钢2150热轧线自动板形控制系统的应用

介绍了鞍钢具有自主知识产权的热轧ASP2150工程板形系统工艺参数和自动板形基础自动化控制系统硬件配置,描述了本系统所采用的工作辊窜辊和弯辊控制策略;建立了前馈ASC、平坦度反馈ASC、凸度反馈ASC(以前受仪表采样频率低限制无此控制)以及全新的板形与板厚解耦控制模型,并进行在线编程、调试。大量生产数据统计表明,投入板形控制后,板形控制精度得到较大提高。     

焦炉加热复合智能控制系统的研究与应用

 焦炉是具有大时滞、强非线性、多变量耦合、变参数的复杂对象。直行温度受多种因素的影响,传统的控制方法难以满足焦炉加热控制的要求。提出了间歇加热控制与加热煤气流量调节相结合的控制原理,利用模糊控制、神经网络等智能控制方法建立了焦炉加热的智能控制策略和模型。该控制策略采用一前馈、二反馈和智能控制相结合。根据焦化机理建立焦炉供热量前馈模型,并提出结焦指数CI反馈模型控制焦炉的炼焦过程。基于线性回归和RBF神经网络构建火道软测量模型,为控制建立温度反馈环节。智能控制方法用于调节停止加热时间和加热煤气流量。最后研究开发了焦炉加热的复合智能控制系统。实际运行结果表明：该系统能够实现焦炉加热的智能控制,稳定了焦炉生产,有效地提高了焦炭质量和降低了能耗,具有很好的实用价值。     

Design of a Single-Pool Downstream Controller Using Quantitative Feedback Control Theory

A downstream controller is designed for an irrigation canal reach using a design technique called quantitative feedback control theory (QFT). The performance of this controller is compared to a proportional, integral, derivative (PID) controller and a linear quadratic regulator (LQR) controller. In this study, the QFT controller is designed for a single canal reach because it best demonstrates how a controller is designed. Previous research for this canal model provided data for comparison. For the operating conditions that are defined in this paper, the QFT controller is shown to have slightly better performance than the PID controller and better performance than the LQR controller. When the canal hydraulic roughness is increased, the QFT controller still performed better than the PID controller.     

Control of Suspension Bridge Nonlinear Vibrations due to Moving Loads

The flexibility and low damping of the long-span suspended cables in the suspension bridges make them prone to vibrations due to wind and moving loads, which affect the dynamic response of the suspended cables and the bridge deck. This paper shows the design of two control schemes to control the nonlinear vibrations in the suspended cable and the bridge deck due to a vertical load moving on the bridge deck with a constant speed. The first control scheme is an optimal state feedback controller. The second control scheme is a robust state feedback controller, whose design is based on the design of optimal controllers. The proposed controllers, whose design is based on Lyapunov theory, guarantee the asymptotic stability of the system. A vertical cable between the bridge deck and the suspended cable is used to install a hydraulic actuator able to generate the active control force on the bridge deck. The MATLAB software is used to simulate the performance of the system with the designed controllers. The simulation results indicate that the proposed controllers are capable of significantly reducing the nonlinear oscillations of the system. In addition, the performance of the system with the proposed controllers is compared to the performance of the system controlled with a velocity feedback controller. It is found that the system with the proposed controllers can provide better performance than the system with the velocity feedback controller.     

Application of Improved Fuzzy Immune PID Controller to Bending Control System

 Based on the hydraulic bending control system, the electrohydraulic servo pressure control simulation model is built. Taking into account of the inadequacy of P-type immune feedback controller, an improved fuzzy immune PID controller is put forward. Drawing on immune feedback principle of biological immune system, the P-type immune feedback controller is connected with conventional PID controller in series and then in parallel with design fuzzy immune PID controller. The controller parameters can be adjusted on line by the rules of immune feedback controller and fuzzy controller. In order to gain the optimal parameters of the controller, the parameters of the controller are off-line optimized by the best multiple optimal model PSO algorithm. The simulation results indicate that the method has characteristics of small overshoot, short adjusting time and strong anti-interference ability and robustness. The quality of the strip shape can be further improved.     

Reliability-Based Performance Objectives and Probabilistic Robustness in Structural Control Applications

A reliability-based structural control design approach is presented that optimizes a control system explicitly to minimize the probability of structural failure. Failure is interpreted as the system’s state trajectory exiting a safe region within a given time duration. This safe region is bounded by hyperplanes in the system state space, each of them corresponding to an important response quantity. An efficient approximation is discussed for the analytical evaluation of this probability, and for its optimization through feedback control. This analytical approximation facilitates theoretical discussions regarding the characteristics of reliability-optimal controllers. Versions of the controller design are described for the case using a nominal model of the system, as well as for the case with uncertain model parameters. For the latter case, knowledge about the relative plausibility of the different possible values of the uncertain parameters is quantified through the use of probability distributions on the uncertain parameter space. The influence of the excitation time duration on feedback control design is discussed and a probabilistic treatment of this time duration is suggested. The relationship to H2 (i.e., minimum variance) controller synthesis is also examined.     

Automatic Downstream Water-Level Feedback Control of Branching Canal Networks: Theory

Most of the research on the design of feedback controllers for irrigation canals has been concentrated on single, in-line canals with no branches. Because the branches in a network are hydraulically coupled with each other, it may be difficult to automatically control a branching canal network by designing separate feedback controllers for each branch and then letting them run simultaneously. Thus feedback control of an entire branching canal system may be more efficient if the branching flow dynamics are explicitly taken into account during the feedback controller design process. This paper develops two different feedback controllers for branching canal networks. The first feedback controller was developed using linear quadratic regulator theory and the second using model predictive control. Both algorithms were able to effectively control a simple branching canal network example with relatively small flow changes.     

Experiments on a Full-Scale Building Model using Modified Sliding Mode Control

This paper presents a modified sliding mode control (MSMC) method using acceleration feedback to reduce the response of seismic-excited civil buildings. A pre-filter is introduced prior to the control command so that a systematic trade-off between control and structural responses can be achieved. To demonstrate practical implementation of MSMC controllers, extensive shake table experimental tests have been conducted on a full-scale three-story building equipped with active bracing systems at the National Center for Research on Earthquake Engineering, Taiwan. To improve the effectiveness of active control, a nominal system that incorporates the control–structure interaction effect is used in the MSMC controller design. In addition, existing system uncertainties in the nominal system resulting from system identification are considered in the process of controller design and the robustness of control performance and stability is demonstrated through shake table experiments. Experimental results indicate that the MSMC strategy using acceleration feedback for the full-scale building is robust and its performance is quite remarkable. Furthermore, the numerical simulation based on an analytical model that was identified previously by taking into account the control–structure interaction effect was conducted and comparisons are made with the experimental results. It is shown that the correlation between numerical simulation results and experimental data is quite excellent.     

Robust Control of Spacecraft Formation Flying

In this paper, a robust control scheme for two spacecraft in formation subjected to time-variant external disturbances in the space environment was developed. The proposed controller consists of two parts, the first part is for the nominal system without disturbances and the second part is to compensate for effects of system disturbances. A dynamic relative motion error model was established to design the second part of the controller and to analyze the stability of the closed-loop system using Lyapunov stability theory. Furthermore, the robustness of proposed control method to the system disturbances is analyzed based on robust control theory. It is proven that the relative motion error of two spacecraft in formation is uniformly ultimately bounded under the proposed controller for the assumed disturbances in the dynamic model.     

无人软翼飞行器直线航迹跟踪鲁棒反步控制

为实现无人软翼飞行器的直线航迹跟踪控制,提出一种基于模拟对象的可变增益鲁棒反步控制方法.基于模拟对象方法建立软翼飞行器的航迹跟踪误差模型,并设计了可变增益反步跟踪控制器,通过合理设计增益参数,消除了部分复杂非线性项,避免了传统反步法中虚拟量高阶导数问题,简化了控制器形式,更有利于工程实现.根据Lyapunov理论设计的鲁棒反馈补偿项,在保证稳定性的同时提高了系统的鲁棒性.将控制器应用于无人软翼飞行器平面直线航迹跟踪控制中,仿真实验表明,所设计的控制器可以实现直线航迹的精确跟踪,且具有很好的鲁棒性.     

Salt River Project Canal Automation Pilot Project: Simulation Tests

The feasibility of automatically controlling water levels and deliveries on the Salt River Project (SRP) canal system through computer-based algorithms is being investigated. The proposed control system automates and enhances functions already performed by SRP operators, namely feedforward routing of scheduled demand changes, feedback control of downstream water levels, and flow control at check structures. Performance of the control system was tested with unsteady flow simulation. Test scenarios were defined by the operators for a 30 km, four-pool canal reach. The tests considered the effect of imperfect knowledge of check gate head-discharge relationships. The combined feedback-feedforward controller easily kept water level deviations close to the target when dealing with routine, scheduled flow changes. Those same routine changes, when unscheduled, were handled effectively by the feedback controller alone. The combined system had greater difficulty in dealing with large demand changes, especially if unscheduled. Because feedback flow changes are computed independently of feedforward changes, the feedback controller tends to counteract feedforward control actions. The effect is unimportant when dealing with routine flow changes but is more significant when dealing with large changes, especially in cases where the demand change cannot be fully anticipated.