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.     

基于观测器具有不确定性的鲁棒保性能控制

在鲁棒性控制问题的研究中,针对系统状态不可测的具有范数有界不确定性和外界干扰的线性系统,其求解过程繁琐,某些参数选取不当.为了保证闭环系统的稳定性,提出一种基于观测器的鲁棒 H∞保性能控制方法.根据李亚普诺夫原理和H∞理论,获得鲁棒H∞保性能控制器存在的一个充分性条件,用矩阵奇异值分解方法,将控制器和观测器存在条件转化为求解一个线性矩阵不等式的可行性.通过凸优化方法,获得最优的线性二次型性能指标和 H∞性能指标.进行仿真的结果表明,上述方法求解简单,稳定性好,验证了所提方法的有效性.     

基于干扰观测器的不确定线性多变量系统控制

针对不确定线性多变量系统,提出一种基于干扰观测器(Disturbance observer,DOB)的保证系统内部稳定性的控制策略.以简单的结构和少量的计算代价实现鲁棒的控制效果,补偿外界干扰以及内部模型误差.通过引入一个闭环稳定性等价系统,辅助分析基于干扰观测器的多变量控制系统的内部稳定性,探讨在存在外部扰动及内部模型不确定性的情况下系统保证内部稳定的充分条件,指导外环控制器及内环干扰观测器中Q滤波器的设计.通过数值模型上的仿真验证了提出的控制方法的有效性.     

一类不确定时滞奇异系统的鲁棒非脆弱控制

针对不确定奇异时滞系统,研究了鲁棒非脆弱控制问题.假定不确定性范数有界,设计了基于观测器的控制器,使得闭环系统在不确定性影响下保持鲁棒稳定.仅通过求解相应线性矩阵不等式就可得到鲁棒状态反馈控制器,该控制器不仅对所有容许的系统不确定性使相应的闭环系统渐近稳定,而且满足控制器本身是非脆弱的,达到抑制干扰的效果.     

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.     

保证闭环系统鲁棒稳定性的干扰观测器系统性设计方法

研究带有干扰观测器(Disturbance observer,DOB)的反馈控制系统对模型不确定性鲁棒稳定的充分条件,在此基础上,选取满足此充分条件的加权函数,使得标准H∞干扰观测器设计方法保证对受控对象参数变化的鲁棒稳定性.提出了在H∞干扰观测器设计中兼顾鲁棒性设计指标和结构约束的频率加权函数的选取方法.利用加权函数选取的自由度,在干扰观测器低通滤波器设计中,实现Q—滤波器在截止频率上的高峰幅度与干扰抑制性能之间的最佳折中,使得干扰观测器在满足其幅度指标的条件下,具有最优干扰抑制性能.实验结果表明该方法保证了闭环反馈系统的鲁棒稳定性,同时,具有实现其他设计指标的自由度.     

基于非线性干扰观测器的翼伞鲁棒反步跟踪控制

针对干扰条件下的无人翼伞飞行器路径跟踪控制问题,提出一种基于非线性干扰观测器的反馈增益鲁棒反步控制方法.采用二阶跟踪-微分器设计干扰观测器对系统复合干扰进行估计和补偿,设计了反馈增益反步跟踪控制律,通过合理设计增益参数,消除了部分复杂非线性项,避免了虚拟量高阶导数问题,简化了控制器形式.根据Lyapunov理论设计鲁棒反馈补偿项,在保证稳定性的同时提高了系统的鲁棒性.仿真实验结果验证了所提出方法的有效性.     

一类不确定时滞奇异系统的鲁棒非脆弱控制

针对不确定奇异时滞系统，研究了鲁棒非脆弱控制问题。假定不确定性范数有界，设计了基于观测器的控制器，使得闭环系统在不确定性影响下保持鲁棒稳定。仅通过求解相应线性矩阵不等式就可得到鲁棒状态反馈控制器，该控制器不仅对所有容许的系统不确定性使相应的闭环系统渐近稳定，而且满足控制器本身是非脆弱的，达到抑制干扰的效果。     

基于自适应模糊状态观测器的非线性系统鲁棒故障检测

针对仿射非线性系统,采用自适应模糊系统进行非线性补偿,提出了一种基于自适应模糊状态观测器的鲁棒故障检测方法.为确保观测器对嗓声干扰和系统参数不确定误差的鲁棒性,给出了闭环系统在有界嗓声干扰和系统参数不确定误差下的稳定性定理,并进行了详尽的证明.仿真结果表明该方法的有效性及对嗓声干扰和系统参数不确定误差的鲁棒性.     

高超飞行器的再入非线性鲁棒控制

针对再入段高超飞行器非线性动力学模型存在不确定性和干扰,基于奇异摄动理论提出了鲁棒变结构+动态逆内外环解耦控制方法.为避免在线实时求逆,控制系统的外环基于简化的模型设计自适应滑模变结构控制律,通过反馈干扰观测器在线估计广义干扰量,实现角度的跟踪和闭环系统的稳定,抑止外来干扰.强耦合的姿态动力学内环采用动态逆跟踪角速度指...     

一类含输入时滞非线性系统的干扰观测器控制

基于干扰观测器控制（Disturbance-observer-based control,DOBC）作为一种有效的干扰补偿策略取得了广泛的应用. 然而,当干扰和控制输入不能在同一时刻进入控制通道时,外部信号很难得到实时估计和补偿.提出一种复合DOBC结构,包括干扰观测、干扰预测和反馈调节三个部分.该方法的特点是即使一类非线性系统存在输入时滞,同样可以继承传统DOBC的优点. 最后,通过构造辅助观测器给出了预测误差以及复合闭环系统的稳定性分析方法.     

Low dimensional disturbance observer‐based control for nonlinear parabolic PDE systems with spatio‐temporal disturbances

In this paper, a design problem of low dimensional disturbance observer‐based control (DOBC) is considered for a class of nonlinear parabolic partial differential equation (PDE) systems with the spatio‐temporal disturbance modeled by an infinite dimensional exosystem of parabolic PDE. Motivated by the fact that the dominant structure of the parabolic PDE is usually characterized by a finite number of degrees of freedom, the modal decomposition method is initially applied to both the PDE system and the PDE exosystem to derive a low dimensional slow system and a low dimensional slow exosystem, which accurately capture the dominant dynamics of the PDE system and the PDE exosystem, respectively. Then, the definition of input‐to‐state stability for the PDE system with the spatio‐temporal disturbance is given to formulate the design objective. Subsequently, based on the derived slow system and slow exosystem, a low dimensional disturbance observer (DO) is constructed to estimate the state of the slow exosystem, and then a low dimensional DOBC is given to compensate the effect of the slow exosystem in order to reject approximately the spatio‐temporal disturbance. Then, a design method of low dimensional DOBC is developed in terms of linear matrix inequality to guarantee that not only the closed‐loop slow system is exponentially stable in the presence of the slow exosystem but also the closed‐loop PDE system is input‐to‐state stable in the presence of the spatio‐temporal disturbance. Finally, simulation results on the control of temperature profile for catalytic rod demonstrate the effectiveness of the proposed method. Copyright © 2015 John Wiley & Sons, Ltd.     

Composite disturbance‐observer‐based control and H∞ control for complex continuous models

A novel type of control scheme combining the disturbance‐observer‐based control (DOBC) with H_∞ control is proposed for a class of complex continuous models with disturbances. The disturbances are supposed to include two parts. One part in the input channel is generated by an exogenous system with uncertainty, which can represent the harmonic signals with modeling perturbations. The other part is supposed to have the bounded H₂‐norm. Parametric uncertainties exist both in concerned plant and in exogenous subsystem. The disturbance observers based on regional pole placement and D‐stability theory are designed and integrated with conventional H_∞ control laws. The new composite DOBC and H_∞ control scheme is applied to complex continuous models for the case with known and unknown nonlinearity, respectively. Then the first type of disturbances can be estimated and rejected, and the second type can be attenuated; simultaneously, the desired dynamic performances can be guaranteed. Simulations for a flight control system are given to demonstrate the effectiveness of the results and compare the proposed results with the previous schemes. Copyright © 2009 John Wiley & Sons, Ltd.     

Disturbance attenuation and rejection for systems with nonlinearity via DOBC approach

In this paper the disturbance attenuation and rejection problem is investigated for a class of MIMO nonlinear systems in the disturbance‐observer‐based control (DOBC) framework. The unknown external disturbances are supposed to be generated by an exogenous system, where some classic assumptions on disturbances can be removed. Two kinds of nonlinear dynamics in the plants are considered, respectively, which correspond to the known and unknown functions. Design schemes are presented for both the full‐order and reduced‐order disturbance observers via LMI‐based algorithms. For the plants with known nonlinearity, it is shown that the full‐order observer can be constructed by augmenting the estimation of disturbances into the full‐state estimation, and the reduced‐order ones can be designed by using of the separation principle. For the uncertain nonlinearity, the problem can be reduced to a robust observer design problem. By integrating the disturbance observers with conventional control laws, the disturbances can be rejected and the desired dynamic performances can be guaranteed. If the disturbance also has perturbations, it is shown that the proposed approaches are infeasible and further research is required in the future. Finally, simulations for a flight control system is given to demonstrate the effectiveness of the results. Copyright © 2005 John Wiley & Sons, Ltd.     

时滞的非完整动力学系统滑模抗干扰跟踪控制

针对具有外部扰动和时滞的非完整轮式移动机器人系统,本文阐述了一种基于非线性扰动观测器的时滞滑模控制方法.首先,利用扰动观测器估计系统的外部扰动;然后,用极坐标转化移动机器人的姿态,并用计算转矩法对机器人的动力学方程进行反馈线性化.设计带时滞控制的滑模,目的是使移动机器人渐近稳定在期望轨迹上,并有效地减小控制增益的过高估计.最后,利用李雅普诺夫函数建立闭环系统的稳定性.仿真结果表明,该方案具有良好的跟踪精度和鲁棒性.     

Composite disturbance-observer-based control and terminal sliding mode control for non-linear systems with disturbances

A novel type of control scheme combining the disturbance-observer-based control (DOBC) with terminal sliding mode (TSM) control is proposed for a class of multiple-input–multiple-output (MIMO) continuous non-linear systems subject to disturbances. The disturbances are supposed to include two parts. One in the input channel is generated by an exogenous system with uncertainty, which can represent the harmonic signals with modelling perturbations. The other is supposed to have the bounded H ₂ norm. The disturbance observers based on regional pole placement and D-stability theory are presented, which can be constructed separately from the controller design. By integrating DOBC with TSM control laws, the disturbances can be rejected and attenuated, simultaneously, and the desired dynamic performances can be guaranteed for non-linear systems in finite time with known and unknown non-linear dynamics, respectively. Two simulation examples for a flight control system and a hard disk drive actuator are given respectively to demonstrate the effectiveness of the proposed control schemes compared with the previous schemes.     

Development of nonlinear disturbance observer based control and nonlinear PID: A personal note

This paper gives an overview of early development of nonlinear disturbance observer design technique and the disturbance observer based control (DOBC) design. Some critical points raised in the development of the methods have been reviewed and discussed which are still relevant for many researchers or practitioners who are interested in this method. The review is followed by the development of a new type of nonlinear PID controller for a robotic manipulator and its experimental tests. It is shown that, under a number of assumptions, the DOBC consisting of a predictive control method and a nonlinear disturbance observer could reduce to a nonlinear PID with special features. Experimental results show that, compared with the predictive control method, the developed controller significantly improves performance robustness against uncertainty and friction. This paper may trigger further research and interests in the development of DOBC and related methods, and building up more understanding between this group of control methods with comparable ones (particularly control methods with integral action).     

Composite disturbance‐observer‐based control and H ∞ control for nonlinear time‐delay systems

A novel type of control scheme combined the distance‐observer‐based control (DOBC) with H_∞ control is proposed for a class of nonlinear time‐delay systems subject to disturbances. The disturbances are supposed to include two parts. One in the input channel is generated by an exogenous system with uncertainty, which can represent the harmonic signals with modeling perturbations. The other is supposed to have the bounded H₂ norm. The disturbance observers based on regional pole placement and D‐stability theory are presented, which can be designed separately from the controller design. By integrating disturbance‐observer‐based control with H_∞ control laws, the disturbances can be rejected and attenuated, simultaneously, the desired dynamic performances can be guaranteed for nonlinear time‐delay systems with unknown nonlinear dynamics. Copyright © 2009 John Wiley and Sons Asia Pte Ltd and Chinese Automatic Control Society     

High‐order mismatched disturbance rejection control for small‐scale unmanned helicopter via continuous nonsingular terminal sliding‐mode approach

In this paper, the problem of finite‐time control for small‐scale unmanned helicopter system with high‐order mismatched disturbance is investigated via continuous nonsingular terminal sliding‐mode control approach. The key idea is to design a novel nonlinear dynamic sliding‐mode surface based on finite‐time disturbance observer. Then, the finite‐time convergence and chattering attenuation capability is guaranteed by the continuous nonsingular terminal sliding‐mode control law. Additionally, rigorous finite‐time stability analysis for the closed‐loop helicopter system is given by means of the Lyapunov theory. Finally, some simulation results demonstrate the effectiveness and predominant properties of the proposed control method for the small‐scale unmanned helicopter even in the presence of high‐order mismatched disturbance.