化工不稳定时滞过程鲁棒控制的解析设计

针对化工不稳定时滞过程,提出一种两自由度控制结构.首先基于鲁棒H2最优性能指标,设计给定值跟踪控制器;然后根据系统稳态运行时的抗负载干扰要求,在过程输入与输出端之间设计控制闭环,利用其反馈通道上的扰动观测器抑制负载干扰,通过提出期望的闭环余灵敏度函数的方法,反向确定扰动观测器,同时给出了该控制闭环保证鲁棒稳定性的充要条件.仿真实例验证了该控制结构的优越性.     

一种可保证瞬态特性的改进的鲁棒模型参考自适应控制

针对典型的鲁棒模型参考自适应控制中瞬态性能无法得到保障的问题, 提出一种改进的鲁棒模型参考自适应控制器. 该控制器在标准的鲁棒自适应控制中加入??_∞ 补偿器, 以抑制闭环自适应系统中参数估计误差和不确定扰动对系统输出跟踪性能造成的不利影响. 理论分析和仿真验证表明, 所提出的控制器不但保留了典型鲁棒模型参考自适应控制的理想特性, 并且通过设计适当的??∞ 补偿器使得闭环系统的瞬态性得到了较大的改善, 其改善的程度依赖于??∞ 补偿器性能指标的大小.

     

磁耦合谐振无线电能传输系统的输出鲁棒控制

磁耦合谐振无线电能传输系统的负载和谐振参数会因为受到外界环境的影响而发生变化, 系统工作频率发生随机漂移, 导致模型参数存在不确定性. 针对参数不确定下的输出鲁棒控制问题, 本文基于H_∞控制理论, 应用Matlab鲁棒控制工具箱设计H_∞控制器, 并基于结构奇异值法分析了闭环系统的鲁棒稳定性与鲁棒性能. 结果表明, 在H_∞控制器的作用下, 实现了闭环摄动系统的输出鲁棒控制, 并为此类高阶非线性不确定闭环系统提供了一种通用的控制器设计方法.     

不确定Delta算子系统的鲁棒H∞重构控制

讨论一类含有参数不确定和执行器故障的Delta算子系统鲁棒H_∞ 重构控制设计问题. 通过利用故障检测与隔离(FDI)技术, 在考虑不可检测故障执行器输入为能量有界的干扰信号情形下, 基于H_∞ 干扰抑制的思想, 给出了系统可鲁棒H_∞ 镇定的充分条件. 所设计的控制器可使闭环系统鲁棒稳定, 而且对可允许的不确定性和执行器故障具有一定的H_∞ 性能. 数值例子说明了本文设计方法的有效性.     

挠性系统基于相位控制的H∞鲁棒设计

提出一种加权的H_∞优化设计方法来设计挠性系统的鲁棒控制器,以解决采用H_∞回路成形法设计时控制器不稳定且鲁棒性差的问题.利用挠性模态所对应闭环极点的配置来实现相位控制思想,同时允许高频部分的闭环极点与期望极点有一定差别,弱化严格正实的约束.将相位控制与H_∞优化求解相结合,通过所求得的控制器实现期望的闭环极点.所提出的设计方法灵活且设计过程物理意义明确.最后通过两个仿真算例验证所提出方法的可行性.     

一类开环不稳定串级控制系统的解析设计

针对化工过程中常见的一类开环不稳定串级控制系统．提出一种新的给定值响应和负载干扰响应解耦的控制结构，从而可分别对其进行在线调节和优化，采用内模控制理论，基于鲁棒H2最优性能指标解析地推导出给定值响应控制器和抑制负载干扰的内外环扰动观测器，从而使控制系统时域响应指标可定量估计和整定，仿真实例验证了该控制结构的优越性。     

典型大时变时滞工业过程的鲁棒数字PⅡ调节控制

通过分析典型大时变时滞工业过程的特性,提出了一种新的数字PⅡ鲁棒调节控制器 的设计方法.应用这种数字鲁棒控制器,闭环系统可具有大时变时滞鲁棒镇定性,且完全抑制定 值负载干扰.数字仿真验证了该方法的有效性.     

具有输入饱和的近空间飞行器鲁棒控制

针对近空间飞行器这一类存在外部扰动,输入饱和和参数不确定的多输入多输出线性系统,提出了一种基于干扰观测器的抗饱和鲁棒控制方案.将干扰观测器与抗饱和控制技术相结合,从而消除系统存在的未知外部扰动、输入饱和和不确定性对系统控制的影响.首先,设计干扰观测器对线性外部系统产生的未知扰动进行估计.然后根据干扰观测器输出,通过超前抗饱和方法设计抗饱和补偿器,并将其加入到鲁棒控制器的设计中,保证闭环系统存在输入饱和、未知外部扰动和参数不确定情况下的稳定性.为便于设计,干扰观测器、抗饱和补偿器和控制器设计矩阵均通过求解线性矩阵不等式得到.最后,将提出的鲁棒抗饱和控制方法应用于近空间飞行器,仿真结果验证了该控制方案的有效性.     

基于干扰观测器的一类奇异系统H∞控制

提出了一种基于干扰观测器的奇异系统鲁棒H_∞控制方法.外部干扰广泛存在于奇异系统中,为了降低其对系统的影响,设计了一种奇异系统干扰观测器以估计系统干扰.然后给出闭环系统相容的条件,设计一种基于干扰观测器的鲁棒控制器,并基于李雅普诺夫稳定性理论证明了闭环系统的渐近稳定性,通过设计指标函数得到闭环系统具有鲁棒性能的条件.相对于传统鲁棒控制方法,基于干扰观测器的方法降低了系统设计的保守性.最后,通过仿真实验验证了所提出方法的正确性和有效性.     

一类具有L∞ 范数有界扰动的非线性系统鲁棒控制

首先针对不确定非线性系统, 基于 L_∞ 范数定义了鲁棒稳定化和鲁棒跟踪控制问题. 然后利用反馈线性化技术和Lyapunov方法, 设计了相应的鲁棒控制器. 仿真结果验证了控制器设计的正确性.     

化工不稳定时滞对象的改进内模控制

针对化工过程中典型不稳定时滞对象,基于传统内模控制提出了两自由度控制方案,新增两个控制器分别用于稳定控制对象和抑制扰动,在镇定不稳定过程的基础上,设定值跟踪控制器和扰动抑制控制器可独立调节而无需再取折衷,同时保证系统具有较好的鲁棒稳定性.最后通过仿真实例验证了该控制方案的有效性.     

不稳定时滞对象的串级控制设计

针对常见的开环不稳定串级过程,提出一种新的解析设计方法.副回路中采用两自由度内模控制结构,减少因副回路设定值响应与扰动抑制响应耦合对主回路性能的影响.主回路采用加滤波器的单位反馈控制结构,基于闭环最优灵敏度函数解析推导出设定值响应控制器,保证系统的整体性能.针对副回路存在的乘性不确定性,分析了系统的鲁棒稳定性,最后通过...     

Direct synthesis based tuning of the parallel control structure for integrating processes

A controller tuned for servo/regulatory application gives significant performance degradation when used for regulatory/servo purpose. The degradation in the overall performance can be minimised by a two degree-of-freedom control structure. The parallel control structure reported recently decouples set-point tracking from disturbance rejection. In the present work, the two controllers of parallel control structure are designed using direct synthesis approach to achieve robust closed-loop performance for a class of integrating processes. Simulation examples show that improved servo and regulatory performances are achieved by the proposed method as compared to the recently reported strategies when the controllers are tuned to have the same degree of robustness.     

Adaptive nonlinear control of pH neutralization processes using fuzzy approximators

In this paper, an adaptive control scheme, based on fuzzy logic systems, for pH control is addressed. For implementation of the proposed scheme no composition measurement is required. Stability of the closed-loop system is established and it is shown that the solution of the closed-loop system is uniformly ultimately bounded and under a certain condition, asymptotical stability is achieved. Effectiveness of the proposed controller is tested through simulation and experimental studies. Results indicate that the proposed controller has good performances in set-point tracking and load rejection and much better than that of a tuned PI controller.     

Enhanced modified Smith predictor for second-order non-minimum phase unstable processes

In this paper, a modified Smith predictor design is proposed for enhanced control of non-minimum phase unstable second-order time-delay processes with/without zero. The proposed method involves the design of two controllers, i.e. set-point tracking controller and disturbance rejection controller. Set-point tracking controller is designed as a proportional-integral-derivative (PID) in series with a lag filter using direct synthesis method. The disturbance rejection controller is designed as a PID in series with a lead/lag filter based on direct synthesis method. Set-point weighting is considered for minimising the overshoots. The proposed method is applied by simulation on several second-order unstable processes. Robustness studies have been carried out using the small-gain theorem. The method gives good nominal and robust control performances. Significant improvement in the disturbance rejection is obtained with the proposed method when compared to the recently reported methods in the literature.     

Simultaneous automatic tuning of cascade control systems from closed-loop step response data

This study presents a novel automatic tuning method for cascade control systems in which both primary and secondary controllers are tuned simultaneously using a single closed-loop step test. The proposed technique identifies the required process information with the help of B-spline series representation for the step responses. The two proportional–integral–derivative (PID) controllers are then tuned using an internal model control (IMC) approach. Considering the rationale of cascade control, the secondary controller is designed for faster disturbance attenuation. Without requiring an additional experiment, the primary controller is designed based on an identified process model that accurately accounts for inner loop dynamics. Finally, this study includes robustness considerations in the controller tuning process, and develops explicit guidelines for the selection of the IMC tuning parameters, completing the automatic tuning procedure for cascade control systems. The proposed method is robust to measurement noise because of the filtering property of the B-splines, and can provide superior control performance for both set-point tracking and disturbance rejection. Simulation examples demonstrate the effectiveness of the proposed automatic tuning method.     

A new design for a PID plus feedforward controller

In this paper, a new design and tuning procedure for a PID plus feedforward controller is proposed. It consists of determining a feedforward signal in order to achieve a predefined process output transition time assuming a first order plus dead time model of the process. Then, the PID parameters are tuned by any conventional method in order to assure a good load disturbance rejection and the reference signal to the closed-loop system is obtained by filtering appropriately the set-point step signal. Simulation and experimental results show that the method outperforms the typical (inverse) model-based approach despite its simplicity and it is therefore suitable to implement in Distributed Control Systems as well as in single-station controllers.     

典型二阶积分对象的新型控制策略

针对工业控制中常见的一类具有时滞的二阶积分对象,根据内模控制原理,提出一种新型控制策略。在该结构中,由参考模型来实现系统期望的设定值跟随响应特性,利用内模控制鲁棒性强的特点来抑制参数变化和干扰对系统的影响,从而使系统获得良好的干扰抑制特性和鲁棒性。调节参考模型参数和内模控制器参数,可使系统同时具有良好的设定值跟随特性和干扰抑制特性。仿真结果表明了方法的优越性。     

Two degree-of-freedom design for a send-on-delta sampling PI control strategy

A complete event-based two-degree-of-freedom PI controller is presented. The architecture of the control system is based on two decoupled PI controllers, one for the set-point following and one for the load disturbance rejection task. The distinctive feature of the proposed approach is that the two controllers have the same parameters and the reference tracking performance is improved by suitably modifying the reference signal applied to the set-point following controller. Examples of the technique are given. In particular, the control strategy has been applied to a distributed solar collector field.     

一阶参数不确定滞后过程的鲁棒PID控制器设计

提出一种针对一阶参数不确定滞后过程的鲁棒PI／PID控制器优化设计方法。首先基于D-分割法技术，给出确定一阶参数不确定滞后过程的整个PI／PID控制器的可行鲁棒稳定域算法；在定义一个与控制器给定点跟踪性能、鲁棒性能和抗扰动性能相关的目标函数的基础上，给出PI／PID控制器设计的约束优化问题；最后应用一种启发式粒子群优化（PSO）算法对该约束问题进行求解。仿真结果表明，所提出的方法可得到更小的调节时间、更小的超调、较强鲁棒性和更好的抗扰动性能，表明了所提出的方法的有效性。