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.     

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.     

Lyapunov-Based Nonlinear Disturbance Observer for Serial n-Link Robot Manipulators

In this paper we extend the work done by Chen et al. (IEEE Trans Ind Electron 47(4):932–938, 2000) which proposed a nonlinear disturbance observer for two-link robot manipulators to n-link robot manipulators. A general form of dynamic equations of serial n-link robot manipulator is considered, and the stability analysis of the proposed observer is performed by using Lyapunov’s direct method. Although it seems that the formulation of disturbance observer is easy to derive, choosing the disturbance observer gain to guarantee stability is really hard. In this paper it is shown that the design parameter can be selected depends on the maximum velocity and physical parameters of robot manipulator to guarantee the global asymptotic stability of the disturbance observer. Using this nonlinear disturbance observer, no accurate dynamic model is required to achieve high precision motion control, because it makes the system robust against internal disturbances such as unmodeled dynamics and external disturbances such as friction in joints. The effectiveness of the proposed observer is investigated by numerical simulation for three-Dofs robot manipulator. In fact, controller with disturbance observer has more superior tracking performance, with a wide range of payloads and in the presence of friction in joints. It is also found that, although the proposed observer is designed for slow varying disturbances, it can estimate rapid time varying disturbances very well.     

基于高阶干扰观测器的极点配置控制器及应用

本文设计了一种可以对外部干扰进行估计的高阶干扰观测器,并针对一类具有外部干扰的单输入单输出离散时间线性系统,提出了一种基于高阶干扰观测器的极点配置控制方法.该方法由常规极点配置控制器和高阶干扰观测器组成.常规极点配置控制器用来保证闭环系统稳定,并将闭环系统的极点配置到理想位置,高阶干扰观测器用来补偿外部干扰对闭环系统的影响.理论分析以及仿真和水箱液位系统中的实验结果表明了所提方法的有效性和优越性.     

Robust control of mismatched buck DC–DC converters by PWM-based sliding mode control schemes

In this paper, two control methods are proposed to control mismatched dc–dc buck converters. In the first method, called Method I, a multiple surface sliding mode control is proposed to handle mismatched load uncertainty. A major problem associated with multiple surface sliding mode control viz. ‘explosion of terms’ is handled by a disturbance observer. Another method, Method II, based on simultaneous state and disturbance observer is proposed as a further improvement over Method I in terms of sensor requirement. The practical stability of the proposed schemes is proved. The performance of both the methods are assessed for regulation and tracking of output voltage under various uncertainties and is compared with a method based on extended state observer. It is shown by simulation and experimentation that the transient and steady state performance of both the controllers are satisfactory.     

Discrete-time track following controller design using a state-space disturbance observer

This paper presents a method to design a discrete-time track following controller using a state-space disturbance observer. To improve sensitivity, an add-on state-space disturbance observer is introduced to a LQG/LTR track following controller, which does not affect the observer and state feedback poles thereby preserving the separation principle. Therefore disturbance observer design is possible to shape the sensitivity without affecting the stability of the LQG/LTR track following controller. The proposed disturbance observer is designed in state-space without disturbance model such as plant's inverse dynamics, periodic signal generator, and Q filter. Simulation and experimental results verify the effectiveness of the proposed design method using a disturbance observer.     

The consistency control of mold level in casting process

A new multiple periodic disturbance rejection control for casting process is proposed in this paper. Firstly, a high-precision multiple periodic disturbance detection method is designed. The accurate frequencies of the disturbance can be obtained. By using the disturbance observer and a group of filters with additional delay items, multiple periodic disturbance can be suppressed under time-delay environment. Then systematic control design is achieved based on the robust stability analysis. Finally, the efficiency of the proposed method is shown by comparisons between different methods and time-varying disturbance rejection in the consistency control of mold level.     

Composite adaptive anti-disturbance control for MIMO nonlinearly parameterized systems with mismatched general periodic disturbances

In this paper, the problem of anti-disturbance control for a class of multi-input and multi-output (MIMO) nonlinearly parameterized systems with mismatched general periodic disturbances is investigated via a composite adaptive anti-disturbance control scheme. The composite adaptive anti-disturbance control method is presented by using disturbance observer technique, back-stepping method and adaptive control approach. A novel disturbance observer is designed to estimate the disturbances generated by a linear system with nonlinear output function. Rigorous stability analysis for the augmented closed-loop system is developed by direct Lyapunov stability theory. It is shown that the system outputs asymptotically converge to zero in the presence of mismatched general periodic disturbances. Finally, a simulation example is given to demonstrate the effectiveness of the proposed method.     

基于自适应神经网络的分数阶混沌系统滑模同步

针对一类异结构不确定分数阶混沌系统的同步问题,基于Lyapunov稳定性理论和分数阶系统稳定性理论,提出一种神经网络结合干扰观测器的主动反馈控制方法. 设计一种非线性干扰观测器对干扰进行观测,通过滑模控制对未观测出的部分干扰进行补偿,最终实现分数阶混沌系统的同步.与现有方法相比,采用的模型更符合工程应用实际,且不需要已知不确定项上界.数值仿真验证了所提出方法的有效性和正确性.     

Disturbance-observer-based robust control for time delay uncertain systems

A robust control scheme is proposed for a class of systems with uncertainty and time delay based on disturbance observer technique. A disturbance observer is developed to estimate the disturbance generated by an exogenous system, and the design parameters of the disturbance observer are determined by solving linear matrix inequalities (LMIs). Based on the output of the disturbance observer, a robust control scheme is proposed for the time delay uncertain system. The disturbance-observer-based robust controller is combined of two parts: one is a linear feedback controller designed using LMIs and the other is a compensatory controller designed with the output of the disturbance observer. By choosing an appropriate Lyapunov function candidate, the stability of the closed-loop system is proved. Finally, simulation example is presented to illustrate the effectiveness of the proposed control scheme.     

基于扰动观测器的机械臂自适应反演滑模控制

机械臂的动力学模型通常包含一定的结构不确定性,并受到外界未知干扰的影响。针对现有模型的不确定性特点,提出了一种基于非线性扰动观测器的自适应反演滑模控制方法,解决机械臂的轨迹跟踪控制问题。对于外界干扰,利用非线性扰动观测器进行观测补偿,无需上界先验知识;对于结构不确定性,引入反演滑模控制,同时设计自适应律,保证闭环系统的稳定性并增强系统的动态适应性。仿真结果证明,所提出的方法可以有效克服系统不确定性,降低控制输入信号的抖振,最终实现期望轨迹的快速精确跟踪。     

考虑测量不确定和输入饱和的充液航天器自适应鲁棒控制

本文研究了三轴稳定充液航天器控制系统中同时存在测量不确定,外部未知干扰,参数不确定和控制输入饱和的鲁棒自适应姿态机动控制问题.建模过程中,将晃动液体燃料等效为粘性球摆模型,采用动量矩守恒定律推导出充液航天器的耦合动力学方程.提出了一种将反步控制方法结合非线性干扰观测器和指令滤波器的鲁棒饱和输出反馈复合控制策略,该控制策略不仅能继承反步控制方法的优点,而且通过引入非线性干扰观测器实现对未知外部干扰,参数不确定以及测量不确定的补偿,还能利用指令滤波器处理控制力矩输入饱和的不利影响.基于Lyapunov稳定性分析方法证明了系统状态变量的渐进稳定性.仿真结果验证了提出控制方法的有效性和鲁棒性.     

线性广义系统的区间观测器设计

本文研究了连续时间线性广义系统的区间观测器设计问题.首先根据正系统的稳定性判据提出了一种基于线性矩阵不等式的广义区间观测器直接设计法,然后通过引入更多的设计自由度进一步放宽了区间观测器的设计条件,扩大了设计方法的适用范围.所提出的设计方法无需坐标变换,是一种直接设计方法.最后,通过两个仿真算例验证了所提出方法的有效性.     

采用速度观测器的多Euler-Lagrange系统一致性跟踪控制

本文针对无向图拓扑网络下的多Euler-Lagrange系统,设计了一种分布式跟踪控制策略.在只有部分智能体能够获取领航智能体信息,且各Euler-Lagrange系统模型未知的情况下,针对领航智能体速度恒定和时变两种情况进行研究,分别设计相应观测器实现了对领航者速度的观测,且观测值的导数连续,并给出了观测器收敛的充分条件.控制器由两部分组成:第1部分是一个神经网络系统的输出,以逼近系统的未知非线性环节,第2部分是一个鲁棒项,以消除逼近误差与系统外部扰动的影响,保证控制量的连续性.采用Lyapunov理论证明了闭环系统的稳定性,通过仿真验证了本文所提算法的有效性.     

Robust adaptive controller with disturbance observer for vehicular radar servo system

In vehicular radar servo system, parameter variations of the executive motor and external disturbance uncertainties have great effects on the position tracking precision of the system. In this paper, a robust adaptive controller with disturbance observer is designed for vehicular radar servo system, which combines the merits of disturbance observer, adaptive backstepping method and sliding mode control. The system is modeled, and a disturbance observer is employed to observe and compensate for the unknown uncertainties. Adaptive backstepping method is used to design the sliding model controller to guarantee the global stability of the overall system. Simulation results show that the proposed robust adaptive controller has good performance in position tracking and enhances the robustness of vehicular radar servo system while observing the uncertainties precisely and quickly.     

基于滤波器的浸入与不变自适应控制

针对机电伺服系统存在参数不确定、未建模动态及时变扰动这一问题,提出一种基于滤波器的浸入与不变自适应算法,该算法能够准确估计伺服系统中的未知参数.首先,构造系统状态及回归函数的滤波器,再根据滤波后的辅助变量构造参数估计器;然后,依据浸入与不变理论设计参数估计器中的辅助函数,从而保证参数估计误差的收敛性.此外,为了进一步降低集总扰动对系统闭环性能的影响,提出一种扰动观测器,这种扰动观测器结构简单,并且能保证估计误差的渐近稳定,从而有效地补偿系统中的未建模动态和外部扰动.最后,利用Lyapunov理论分别证明了参数估计器、扰动观测器及闭环系统的稳定性,仿真与实验结果验证了所提出的自适应方法及扰动观测器的有效性.     

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.     

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.     

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.     

输出约束的有限时间自适应区间二型模糊输出反馈PMSM伺服控制

针对永磁同步电机驱动的伺服系统在不确定性摩擦和未知负载的影响下难以达到高精度的控制效果,提出一种基于区间二型模糊系统的带有输出约束的有限时间自适应输出反馈控制方案.首先,构建一个基于非线性扰动观测器的区间二型模糊状态观测器,分别完成对于未知扰动和速度的估计,区间二型模糊系统完成对于非线性摩擦的逼近;然后,在此基础上,结合滤波误差补偿机制和有限时间技术,引入障碍Lyapunov函数和反步控制技术设计输出约束的自适应区间二型模糊输出反馈控制器;最后,根据Lyapunov稳定性理论提出严格的稳定性分析,保证闭环系统的所有信号均是有限时间内有界的,并通过数值仿真和实验验证了所提出方法的有效性.