一类不确定非线性系统的自适应模糊滑模控制

针对一类不确定非线性系统自适应模糊控制中,为了保证系统稳定性而附加监督控制问题,根据滑模控制原理并利用模糊系统的逼近能力,提出了一种Ⅰ型间接自适应模糊滑模控制方法。该方法取消了监督控制,用滑模控制器增加了逼近误差的自适应补偿,李雅普诺夫稳定性理论分析证明,控制系统全局稳定且跟踪误差收敛到零。将这种控制器应用到过程控制的典型对象液位控制中,仿真结果表明了该控制器的有效性和可行性。     

一类不确定非线性系统的自适应模糊跟踪控制

针对一类不确定非线性连续系统，用模糊系统对未知函数进行逼近的基础上，利用Lyapunov稳定性理论，提出了一种新的自适应模糊跟踪控制算法，此算法的特点是，无论取多少条模糊系统的规则，自适应学习的参数只有一个，便于实现，而且还能确保闭环系统渐近稳定，并使系统的跟踪误差为零，仿真研究表明，所提出的算法是有效的。     

有输入饱和的欠驱动VTOL飞行器滑模控制

垂直起降飞行器(vertical take-off and landing,VTOL)是典型的非线性、欠驱动系统,实际工程中VTOL飞行器的执行机构通常有饱和特性,针对这种模型的特点,对原始数学模型进行了解耦坐标变换,通过可逆坐标变换化成一个最小相位系统和一个非最小相位系统,之后采用滑模设计方法设计控制器。为了解决执行机构的饱和问题,将超出饱和受限的部分回馈到控制器中,构造一个赫尔伍兹稳定的辅助线性系统,然后把它加入到滑模控制器之中,在控制器中做补偿。利用李雅普诺夫函数证明了系统的稳定性。仿真结果表明,此方法可有效地解决输入受限的VTOL飞行器的镇定和轨迹跟踪问题。     

基于模糊神经网络滑模控制器的一类非线性系统自适应控制

虽然滑模控制具有控制简单和对不确定性与扰动不灵敏等优点，但是控制信号中的颤动是其应用中需解决的主要问题。该文首先针对一类非线性系统提出了一个新型控制器-模糊神经网络滑模控制器。新控制器不仅能消除颤动，而且比一般滑模控制器具有更强的鲁棒性。然而它与一般滑模控制器相比有较大的跟踪误差。为了解决这个问题，提出了结合滑控制器和模糊神经网络滑模控制器的自适应控制方法。这种自适应控制方案可以减小跟踪误差，增强系统的鲁棒性和消除控制信号中的颤动。仿真结果说明了控制方案的有效性。     

不确定多时滞系统的滑模控制

研究了带有不匹配参量不确定性和匹配外扰的多时滞系统的鲁棒滑模控制.通过线性矩阵不等式给出了滑模面存在的一个时滞无关充分性条件,在此基础上设计变结构控制律,实现滑模控制.最后通过仿真说明该控制策略的有效性.     

基于转矩观测器的模糊滑模控制交流伺服驱动系统

本文从滑模变结构理论出发,结合智能控制,针对磁理控制的电主轴永磁同步电机伺服驱动系统设计了带负载转矩观测的模糊滑模变结构控制器。仿真结果表明该方案能使系统获得优良的动静态性能,对负载扰动具有很强的抑制能力,证明了模糊滑模变结构控制方法的合理和优越。     

欠驱动船舶航迹跟踪指令滤波滑模鲁棒控制

为实现欠驱动船舶在模型参数不确定和外界风浪流干扰情况下水平面的航迹跟踪控制,提出了一种指令滤波滑模鲁棒控制方法。利用指令滤波结合反步法建立航迹跟踪误差方程,设计船舶纵向速度和艏摇角的虚拟控制律镇定航迹跟踪误差,并进一步设计船舶艏摇角速度虚拟控制律镇定艏摇角误差;将船舶纵向速度和艏摇角速度的虚拟控制律作为新的跟踪目标,采用积分方法设计基于上下界的滑模控制器,克服了常规反步法对虚拟控制律求导复杂的问题,避免了微分运算在工程应用中难以接受的缺陷和控制输入的抖振现象以及减小稳态误差。仿真实验表明,设计的控制器对欠驱动船舶的模型参数摄动及外界干扰变化不敏感,能够同时实现水平面直线和曲线的精确跟踪。     

一类欠驱动Lagrangian系统的位置同步控制

针对多个单输入欠驱动Lagrangian系统的同步控制问题,根据所定义的同步运动系统的同步误差信号,将各轴的位置误差与位置同步误差的比例耦合项作为新的状态变量,采用递阶滑模控制方法设计了一种交叉耦合位置同步控制器。采用该控制策略,对由两部一级倒立摆实际设备构成的同步运动装置的实时控制实验结果和4部一级倒立摆同步运动系统进行了仿真。仿真结果表明,在闭环系统精确跟踪指令信号的同时保证了各子系统间协调同步运动,而且该同步控制器的同步性能优于积分耦合同步控制器的性能。     

两类不确定非线性系统的最优控制

通过非线性系统的部分线性化方法,将两类各自满足相应条件的不确定非线性系统的最优控制问题分别变换成参数确定和参数不确定线性系统的二次型最优调节器问题,从而求得原最优控制问题的闭环解析解。两个设计例子及其仿真结果验证了本文方法的正确性。     

具有不确定参数的混沌系统的模糊保代价控制

研究了具有不确定参数混沌系统的稳定模糊保代价控制问题。采用T-S模糊模型描述混沌非线性系统，对具有范数有界，时变参数不确定性的混沌系统，得到了存在稳定模糊保代价控制器的充分条件。并推算出了相应的线性矩阵不等式(LMI)形式。     

一种不确定非线性系统的滑模变结构观测器的研究

由于工程实际中大部分工业对象均为非线性系统,滑模观测器应用研究的重点已从线性系统转至不确定非线性系统。针对一类非线性满足Lipschitz条件,而不确定部分为有界函数的不确定非线性系统,提出一种滑模变结构观测器设计方案,将基于线性系统提出的Walcott-Zak观测器用于抑制非线性对系统的影响,而滑模变结构使得观测器对系统不确定性具有鲁棒性。对所设计观测器的稳定性进行了证明,并通过仿真验证了所提方法的有效性。     

基于神经网络的一类非线性系统自适应滑模控制

针对可以分解为标称系统和不确定系统两部分的SISO非线性系统,提出了一种基于神经网络的自适应滑模控制方案。控制器由标称控制律和补偿控制律组成,标称控制律用来控制标称系统,补偿控制律是基于Lyapunov稳定性理论设计的自适应神经滑模控制律,用来控制不确定系统,而神经网络用来逼近系统的不确定性。理论分析和计算机仿真都证明,本文提出的控制策略不但能解决这类系统的轨迹跟踪控制问题,而且可以保证闭环系统的渐近稳定性。     

Passivity‐based sliding mode control for nonlinear systems

Passivity with sliding mode control for a class of nonlinear systems with and without unknown parameters is considered in this paper. In fact, a method for deriving a nonlinear system with external disturbances to a passive system is considered. Then a passive sliding mode control is designed corresponding to a given storage function. The passivity property guarantees the system stability while sliding mode control techniques assures the robustness of the proposed controller. When the system includes unknown parameters, an appropriate updated law is obtained so that the new transformed system is passive. The passivation property of linear systems with sliding mode is also analysed. The linear and nonlinear theories are applied to a simple pendulum model and the gravity‐flow/pipeline system, respectively. Copyright © 2008 John Wiley & Sons, Ltd.     

Sliding mode disturbance observer‐based adaptive control for uncertain MIMO nonlinear systems with dead‐zone

In this paper, an adaptive integral sliding mode control (ISMC) scheme is developed for a class of uncertain multi‐input and multi‐output nonlinear systems with unknown external disturbance, system uncertainty, and dead‐zone. The research is motivated by the fact that the ISMC scheme against unknown external disturbance and system uncertainty is very important for multi‐input and multi‐output nonlinear systems. The system uncertainty, the unknown external disturbance, and the effect of dead‐zone are integrated as a compounded disturbance, which is well estimated using a sliding mode disturbance observer (SMDO). Then, the adaptive ISMC based on the designed SMDO is presented to guarantee the satisfactory tracking performance in the presence of system uncertainty, external disturbance, and dead‐zone. Finally, the designed adaptive ISMC strategy based on SMDO is applied to the attitude control of the near space vehicle, and simulation results are presented to illustrate the effectiveness of the proposed adaptive ISMC scheme using the SMDO. Copyright © 2016 John Wiley & Sons, Ltd.     

非匹配不确定多变量系统高阶终端滑模控制

针对一类具有非匹配不确定性的多变量系统,提出了一种递阶结构的高阶终端滑模控制方法.将多变量系统变换为解耦块能控标准型.采用非奇异终端滑模,结合微分估计器,设计高阶滑模控制策略,使输入输出子系统的状态在有限时间内收敛至平衡点,内部子系统的状态收敛至平衡点的邻域内.所提方法可以简化系统结构,消除控制抖振,通过控制器参数和非匹配扰动的上界可以估计系统状态的收敛范围.仿真结果验证了该方法的有效性.     

永磁同步电机的模糊滑模控制

为了实现高性能永磁同步电动机伺服系统快速而精确的位置跟踪控制,在滑模控制策略中引入模糊控制算法,设计了基于模糊规则的滑模控制器。通过理论分析和控制仿真,证实了模糊滑模控制很好地解决了抖振问题,对参数变化和负载扰动具有较强的鲁棒性,永磁同步电机可获得优良的位置跟踪效果。     

Adaptive sliding mode observer design for a class of uncertain systems

State feedback method is quite popular in control engineering field. However, some popular properties of state feedback approach cannot be used while any of the system states cannot be obtained beforehand. Therefore, this paper proposes a new observer design for a class of uncertain systems through sliding mode control theory. Based on strictly positive real concept, the stability of the equivalent error system is verified. Further, by using the generalized matrix inverse approach, the proposed switching term can drive the error states to zero, and it ensures the global reaching condition of the sliding mode of the error system. Moreover, the presented sliding mode observer is proposed to possess the invariance property to the uncertainty and/or external disturbance. Furthermore, the developed sliding mode observer is extended to release the limitation of knowing the bounds of the lumped perturbations in advance. That is, not only a new sliding mode observer but also a new adaptive sliding mode observer is proposed in this paper. Finally, three examples are illustrated to demonstrate the validity of the proposed sliding mode observer and the proposed adaptive sliding mode observer. Copyright © 2014 John Wiley & Sons, Ltd.     

Event-triggered integral sliding mode control of Takagi-Sugeno fuzzy stochastic systems

This article analyzes the integral sliding mode control (ISMC) problem for the nonlinear stochastic system by employing the fuzzy approach. Firstly, the Takagi-Sugeno (T-S) fuzzy stochastic model with unknown nonlinear function and external disturbance has been developed. Based on the fuzzy model, an observer-based integral sliding mode fuzzy controller is derived under the event-triggered scheme (ETS). The Lyapunov-Krasovskii functionals (LKFs) involving double and triple integral terms are considered and evaluated by applying Writinger inequality lemma and reciprocally convex combination lemma. With the help of matrix's singular value decomposition lemma, the stability conditions have been derived which is in terms of linear matrix inequalities (LMIs) and this can be solved by MATLAB LMI toolbox. Two numerical examples are provided to demonstrate the usefulness of our theoretical conclusions.     

Sliding mode control for a class of uncertain nonlinear system based on disturbance observer

In this paper, a sliding mode control (SMC) scheme is proposed for a class of nonlinear systems based on disturbance observers. For a nonlinear system, the disturbance that cannot be directly measured is estimated using a nonlinear disturbance observer. By choosing an appropriate nonlinear gain function, the disturbance observer can well approximate the unknown disturbance. Based on the output of the disturbance observer, an SMC scheme is presented for the nonlinear system, and the stability of the closed‐loop system is established using Lyapunov method. Finally, two simulation examples are presented to illustrate the features and the effectiveness of the proposed disturbance‐observer‐based SMC scheme. Copyright © 2009 John Wiley & Sons, Ltd.