基于改进Smith预估控制结构的二自由度PID控制

针对工业过程中的二阶不稳定时滞过程, 基于改进史密斯预估控制结构提出了一种简单的两自由度控制方案.设定值跟踪控制器和扰动抑制控制器采用同一设计程序, 并基于内模控制原理提出了控制器解析设计方案.设定值跟踪控制器和抗扰动控制器可分别通过单性能参数独立调节和优化, 每个控制器都具有PID形式, 给出了控制器调整参数的选择范围和扰动抑制闭环保证鲁棒稳定性的条件.仿真实例验证了提出方法对于近期其他方法的优越性.     

非自衡时滞对象的改进内模控制

针对化工生产中常见的具有积分和时滞特性的过程对象，采用一种改进的两自由度内模控制方案．其中一个新增的控制器用于设定值跟踪响应的期望极点配置，利用直接合成法设计设定值跟踪控制器；另一个新增的控制器用于稳定对象和抑制扰动，并采用期望闭环余灵敏度法确定控制器．设定值跟踪控制器和扰动抑制控制器可通过性能参数独立调节，并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控制方案的有效性．     

非自衡时滞对象的改进内模控制

针对化工生产中常见的具有积分和时滞特性的过程对象,采用一种改进的两自由度内模控制方案．其中一个新增的控制器用于设定值跟踪响应的期望极点配置,利用直接合成法设计设定值跟踪控制器;另一个新增的控制器用于稳定对象和抑制扰动,并采用期望闭环余灵敏度法确定控制器．设定值跟踪控制器和扰动抑制控制器可通过性能参数独立调节,并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控制方案的有效性．

     

具有时滞的积分和不稳定对象的鲁棒控制

针对含时滞的积分和不稳定对象提出了一种新颖的两自由度控制结构,首先用一个比例控制器镇定给定值响应,然后基于鲁棒H₂最优性能指标设计给定值跟踪控制器.根据实际运行抗干扰要求,在对象输入和输出端之间设计负载扰动抑制闭环,利用扰动观测器抑制负载干扰信号,通过提出期望的闭环余灵敏度函数来确定扰动观测器,同时给出了扰动抑制闭环保证鲁棒稳定性的充要条件.最后通过仿真实例验证了该方法相对于近期其它方法的优越性.     

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.     

大时滞工业过程的双控制器结构

提出一种简单实用的双控制器方案,用于大时滞工业过程控制.该方案含两个独立 的控制器,即跟踪控制器和扰动控制器,使设定值响应得以与扰动响应分离,从而可同时获得 良好的设定值跟踪性能和抗干扰能力.双控制器系统含过程模型,但对过程模型不敏感,因而 鲁棒性好.文中将两个控制器设计为比例加积分(PI)类型,给出了具体的参数整定方法.     

具有边界扰动的不确定Euler-Bernoulli梁方程输出反馈控制

针对带有边界扰动、内部不确定扰动和外部扰动的Euler-Bernoulli梁方程,为克服传统扰动观测器引入的高增益及未知扰动导数难以准确求解问题,本文将主动干扰抑制控制(ADRC)技术应用到Euler-Bernoulli梁方程这个偏微分方程(PDE)系统上,提出并设计了一种新的在线扰动观测器,可实时估计扰动值.依据估计扰动值,设计了一个边界输出反馈控制器.仿真结果表明,本文所提出的方法可很好地实现对内部不确定扰动和外部扰动的估计,配合输出反馈控制器,可对边界扰动进行有效抑制,进而实现系统的指数稳定.     

具有大不确定性对象的分层切换控制方法

针对大模型不确定性对象的控制问题,提出了一种基于鲁棒控制理论的多模型分层切换控制方法.为减少覆盖不确定性需要的模型数量,采用多个乘性不确定模型来描述对象,并应用LMI方法设计控制器集合.考虑鲁棒控制中常用系统增益来度量不确定性,设计了一种基于不确定性增益估计的切换指标函数,并据此将控制器集合中合适的控制器连接到反馈回路中.理论分析表明系统BIBO稳定,且具有一定的扰动抑制能力.仿真实验结果验证了控制方法的有效性.     

以幂次趋近的离散变结构重复控制

本文提出一种离散变结构重复控制器设计方法,在趋近律中“嵌入”扰动抑制措施,构造理想切换动态,并据此导出重复控制器.为了进行控制器参数整定和刻画闭环系统的收敛性能,文中推导出准滑模带、单调收敛层和绝对收敛层边界的表达式.设计的离散变结构重复控制器能够完全抑制周期性扰动,控制器设计方法也适用于常值扰动下的定位控制.数值仿真及实验结果验证了所提出控制方案的有效性.     

模糊PID控制在变风量空调系统中的应用

针对被控对象大惯性、不确定特点,提出一种变风量空调系统室温智能控制方案,建立了变风量空调系统的数学模型,采用了串级控制策略,主控制器采用一种新的可变论域自适应模糊PID控制.用串级控制反馈控制改善性能,抑制一、二次扰动,减小了各种扰动对室温的影响.采用可变论域自适应模糊PID控制.进行仿真.结果证明,变风量空调系统具有良好的动态性和稳定性.当空调房间模型结构参数发生变化时,控制系统鲁棒性好.     

A Novel Boundary Control Solution for Unstable Heat Conduction Systems Based on Active Disturbance Rejection Control

In this study, a new boundary control scheme is proposed for a class of unstable heat conduction systems based on active disturbance rejection control and frequency domain analysis methods. The unstable heat conduction systems studied here corresponds to a thin rod with surface heat loss and internal heat generation. An active disturbance rejection boundary controller is designed to stabilize the unstable heat conduction systems. Using the frequency domain analysis method, the Nyquist stability criterion for distributed parameter systems, the relative stability indices (gain margin, phase margin, and exponential stability speed) can be obtained for performance evaluation, and a constructive parameter‐tuning method for controller is proposed. Finally, it is proved that an active disturbance rejection boundary controller can stabilize the unstable heat conduction systems with one unstable pole, and the simulation results demonstrate that the temperature profile of the whole rod has good convergence properties under both Dirichlet and Neumann boundary control.     

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.     

带有常数干扰的正则线性系统的镇定

本文考虑带有常数干扰的抽象正则线性系统的状态反馈镇定问题.本文控制设计采用线性系统的动态补偿方法,将传统的PID控制推广到无穷维正则线性系统.通过引入积分作用,控制器可以有效地补偿常数干扰.论文给出了具体的状态反馈法则,并证明了对应闭环系统的指数稳定性.理论结果被应用于带有常数干扰的不稳定热方程,给出了控制器及其闭环系统的指数稳定性,数值仿真验证了本文理论结果的有效性.     

A unified design for feedback-feedforward control system to improve regulatory control performance

The PID controller is widely used in industries because of its simplicity and robustness. A simple approach to improve regulatory control performance is to combine both feedback PID and feedforward controllers. The feedforward controller enables early compensation of a measured disturbance before it can seriously affect the process. The conventionally derived non-ideal feedforward controllers are not often used in practice. The reason is that an ideal feedforward controller based on direct inversion of process model is often not physically realizable. Several non-ideal feedforward control designs have been proposed where some of them involve rather intensive tuning procedure to obtain good disturbance rejection. In this paper, we present a new systematic method for designing a combined feedback-feedforward control system. The proposed design method is easy to use and applicable to stable, unstable and integrating deadtime processes where the ideal feedforward controller is physically not realizable.     

Two-port control system: a generalized predictive controller

The two-port control system is introduced to develop the design framework for multivariable predictive controllers. It constitutes a general form for all two-degrees-of-freedom control systems and is particularly suited for the optimum resolution of controller design trade-offs, such as performance to command following versus disturbance rejection, and performance in the presence of various disturbance inputs. It allows the handling of systems with non-minimum phase characteristics or inherently unstable open-loop dynamics. Finally, it offers the necessary and sufficient conditions for the design of effective adaptive control strategies.     

Analytical design of two-degree-of-freedom control scheme for open-loop unstable processes with time delay

This paper proposes an analytical two-degree-of-freedom control scheme for open-loop unstable processes with time delay, which leads to the remarkable improvement of regulatory capacity for both of reference input tracking and load disturbance rejection. Firstly a conventional proportional or plus derivative controller is deliberately employed for stabilizing the setpoint response. Then the setpoint tracking controller is analytically derived in terms of the integral-squared-error (ISE) performance specification. By proposing the desired closed-loop complementary sensitivity function for rejecting load disturbances, the corresponding controller, i.e. disturbance estimator, is inversely figured out. Hence the nominal setpoint response is decoupled from the load disturbance response by virtue of the open-loop control manner for the setpoint tracking. In consequence, both of them can be optimized simultaneously and separately. At the same time, robust stability analysis for the proposed control structure is provided in the presence of the process multiplicative uncertainty. Accordingly the on-line tuning rule for the single adjustable parameter of each controller is suggested to cope with the process unmodeled dynamics in practice. Finally, several illustrative examples are included to demonstrate the superiority of the proposed method.     

Control of the Tennessee Eastman process using input-output models

This paper presents a case-study where model predictive control is applied to control a nonlinear, open-loop unstable process called the Tennessee Eastman Challenge Process. Both the base case and transitions between different operating points are considered. The control scheme is based on an input-output model identified from plant data. The Model Predictive Controller (MPC) controller acts as a supervisory controller that dictates the setpoints for a lower level PID loop structure. Simulations are presented to illustrate its effectiveness or disturbance rejection and setpoint tracking.