Anti-disturbance dynamic surface control scheme for a class of uncertain nonlinear systems with asymmetric dead-zone nonlinearity

This study proposes anti-disturbance dynamic surface control scheme for nonlinear strict-feedback systems subjected simultaneously to unknown asymmetric dead-zone nonlinearity, unmatched external disturbance and uncertain nonlinear dynamics. Radial basis function-neural network (RBF-NN) is invoked to approximate the uncertain dynamics of the system, and the dead-zone nonlinearity is represented as a time-varying system with a bounded disturbance. The nonlinear disturbance observer (NDO) is proposed to estimate the unmatched external disturbance which further will be used to compensate the effect of the disturbance. Then, by integrating RBF-NN, NDO and dynamic surface control (DSC) approaches, the proposed anti-disturbance control scheme is designed. Stability analysis of the closed-loop system shows that all signals of the closed-loop system are semi-globally uniformly ultimately bounded and the tracking error can be made arbitrarily small by proper selection of the design parameters. In comparison with the existing methods, the proposed scheme deals with the unmatched external disturbance, uncertain dynamics and unknown asymmetric dead-zone nonlinearity, simultaneously; it avoids the "explosion of complexity" problem and develops the simple control law without singularity concern. Furthermore, some imposed assumptions to the dead-zone input and disturbances are relaxed. Simulation and comparison results verify the effectiveness of the proposed approach.     

H桥级联STATCOM自适应死区补偿方法

为消除死区效应对H桥级联静止同步补偿器(STATCOM)输出电压及电流的影响,提出一种新的死区补偿方法.根据离散扰动观测器的工作原理,设计相应的观测器,对由于死区效应引起的STATCOM输出电压与参考电压的差值进行实时在线观测,并将观测到的差值作为补偿量,引入到无差拍控制系统中,实现对死区的自适应补偿.仿真与实验结果表明,该方法可以有效地提高死区补偿效果,消除零点电流箝位现象,降低STATCOM输出电流的谐波含量.     

基于迭代学习控制的混合误差轮廓控制

针对永磁直线同步电动机直接驱动XY平台系统中存在不确定扰动的问题,单轴上设计了基于干扰观测器的迭代学习控制器.迭代学习控制器可以抑制重复扰动,干扰观测器可以消除非重复扰动的影响,两者结合起来可增强系统对重复和非重复扰动的抑制能力.由于轮廓误差计算模型要求跟踪误差远小于期望轮廓曲率半径,所以设计了混合误差轮廓控制器,跟踪误差较大时只控制各轴位置,跟踪误差足够小时进行轮廓控制.仿真结果表明,该控制方法使直接驱动XY平台具有较强的鲁棒性和较高的轮廓精度.     

自抗扰技术在四旋翼飞行姿态控制中的应用

介绍了自抗扰控制器的结构组成,包括跟踪微分器、扩张状态观测器以及非线性状态误差反馈律,并给出了各部分的典型算法．针对四旋翼盘旋系统的姿态控制问题,设计了连续型和离散型两种自抗扰控制器,在Simulink下搭建了仿真结构图,并进行了参数整定．仿真结果表明,文中所设计的自抗扰控制器可以满足控制精度及快速性的要求,并且具有强鲁棒性、抗干扰性能以及对非线性强耦合系统的解耦能力．     

Effective model based fault detection scheme for rudder servo system

The inherent nonlinearities of the rudder servo system（RSS） and the unknown external disturbances bring great challenges to the practical application of fault detection technology. Modeling of whole rudder system is a challenging and difficult task. Quite often, models are too inaccurate, especially in transient stages. In model based fault detection, these inaccuracies might cause wrong actions. An effective approach, which combines nonlinear unknown input observer（NUIO） with an adaptive threshold, is proposed. NUIO can estimate the states of RSS asymptotically without any knowledge of external disturbance. An adaptive threshold is used for decision making which helps to reduce the influence of model uncertainty. Actuator and sensor faults that occur in RSS are considered both by simulation and experimental tests. The observer performance, robustness and fault detection capability are verified. Simulation and experimental results show that the proposed fault detection scheme is efficient and can be used for on-line fault detection.     

基于干扰观测器的多光伏光柴混合系统协调控制研究

提出了一种基于干扰观测器的多光伏光柴混合系统协调控制方法,并与采用最大功率跟踪控制而不加协调的多光伏系统的供电效果进行了对比.仿真结果证明,该方法减小了光柴混合系统的频率偏差,并且使各个光伏系统获得了较大功率输出.     

一种多变量自抗扰控制结构的设计研究

自抗扰控制器(active disturbance rejection control,ADRC)不依赖于被控系统的完全模型,采用扩张状态观测器(extended state observer,ESO)对系统的内扰和外扰进行实时估计,因而能取得较为理想的抗干扰效果。对于多变量系统,分散ADRC可以将通道之间的耦合看成扰动,通过各自通道的ESO进行估计。对于强耦合的多变量系统,分散ADRC可能不能及时消除耦合。本文提出一种多变量型ADRC控制结构,将静态解耦引入到ADRC控制器设计中,从而能充分利用系统已知动态特性,实现更好的解耦。采用所提方案对循环硫化床锅炉燃烧系统设计多变量ADRC控制方案,仿真结果表明该控制器具有很好的解耦性和鲁棒性。     

含未知参数和输出不确定性的Lipschitz非线性系统自适应观测器设计

对含未知参数且输出带有不确定性的Lipschitz非线性系统,本文提出了一种自适应观测器的设计方法。当该系统输出的不确定性部分满足Lipschitz条件时,本文给出了系统观测器的结构形式,通过黎卡提方程和矩阵不等式的求解给出观测器增益矩阵的选取方法和参数估计的自适应律, 基于Lyapunov方法证明系统的状态估计误差是一致有界的。仿真结果验证了提出的自适应观测器设计的有效性。     

基于扩张状态观测器的混合式配电变压器直流母线电压控制

混合式配电变压器能够有效抑制电网谐波和稳定负载侧电压,在配电网末端具有重要意义.针对负载变化、电网电压波动或三相不平衡等情况下,混合式配电变压器直流母线电压不稳定导致的谐波补偿、维持负载电压稳定功能出现的问题,提出一种基于非线性扩张状态观测器的直流母线电压控制策略,将观测出的总扰动通过前馈的方式进行补偿,以提高直流母线电压的稳定性.同时,通过频域分析了所设计扩张状态观测器和电压控制器的稳定性.最后,在MATLAB/Simulink仿真与实验中,与比例-积分控制进行对比,证明了所设计控制器的响应速度更快,稳定性更好.     

基于自适应高增益观测器的永磁同步电机预测电流控制方法

针对永磁同步电机(permanentmagnetsynchronous motor,PMSM)预测控制系统的模型失配、时变矩阵及观测器增益选择问题,提出基于自适应高增益观测器的预测电流控制方法(predictive current control based on an adaptive high-gain observer,AHGOPCC)。通过构建PMSM的前馈型扩张数学模型,集成考虑电机电阻、电感、磁链参数扰动项。提出基于前馈型扩张标称数学模型的高增益观测器,有效跟踪和估计电流与扰动状态及抑制转速变化引起的扰动。同时,设计自适应观测器增益矩阵满足全速工况的高增益条件,简化观测器的增益选择。在此基础上,构建离散化电流模型和成本函数,实现预测电流控制算法。实验结果证明了该方法的有效性,在多种工况下具备更优的快速性、鲁棒性及稳定性。