KX容错观测器

本文提出了多输出系统KX观测器的一种新的设计方法.当多输出系统的某些输出测量值不可靠时,得到的KX观测器仍能渐近重构原系统的部分状态信息,一旦那些不可靠的输出恢复正常时,该观测器又能渐近重构原系统的所有状态的信息.     

一类非线性切换系统的观测器设计

研究了一类切换规则为时间依赖型的非线性切换系统的观测器设计问题．分别在切换序列已知与平均驻留时间已知的情况下利用线性矩阵不等式（LMI）给出了非线性项满足Lipschitz条件的切换系统的观测器增益求解方法,并给出了观测器设计步骤．最后给出仿真算例说明了本文方法的有效性．     

一类非线性系统的故障重构与容错控制

针对一类满足Lipschitz条件的仿射非线性系统,提出一种执行器故障重构与容错控制方法。通过非奇异变化矩阵对系统进行降阶,设计出滑模故障重构观测器,优化滑模策略,使滑模故障重构观测器渐进估计系统的状态,并给出稳定性分析。运用等价输出控制方法直接获取故障信息,实现执行器故障的检测与重构。设计出主动容错控制器,通过补偿控制,完成执行器故障的容错控制。最后通过数值仿真验证了方法的可行性与有效性。     

控制器失效的容错切换律设计

针对所有控制器同时失效的情况,研究系统容错切换律的设计问题,发展了圆锥切换律,分析了系统稳定的充分条件,通过在不稳定控制器之间切换来保证系统稳定的控制效果。基于系统的状态和子系统的运动方向选择控制器,可保证系统具有最快的收敛速度。对于子系统同向和逆向的系统分别作了数值仿真,验证了结论的有效性。     

基于观测器的非线性网络控制系统容错控制

研究了一类基于观测器的非线性连续网络控制系统容错控制器设计问题.针对传感器采用时间驱动方式,控制器和执行器均采用事件驱动方式的网络控制系统,设计了观测器,建立了基于状态观测器的增广闭环系统模型.利用线性矩阵不等式和自由权矩阵的方法,推导出闭环系统渐近稳定的充分条件,给出了观测器和容错控制器协同设计的方法.实例仿真证明了所用方法的有效性.     

区间切换系统的状态观测器设计

讨论一类区间切换系统状态观测器的设计问题。采用共同Lyapunov函数方法、多Lyapunov函数方法,设计出状态观测器和相应的切换策略,以线性矩阵不等式的形式给出保证误差系统渐近稳定的充分条件。仿真算例验证状态观测器的有效性。     

一类非线性切换系统的观测器设计

针对在实际工程系统中量测设备在经济性与使用性上存在限制,系统状态通常不能完全观测的问题,考虑了含李普希兹非线性干扰项的切换系统观测器设计问题,通过设计适当的切换策略,提出了一种全局二次稳定的观测器设计方案。该方案适用于有限和无限切换系统,其主要结果以线性矩阵不等式(LMI)的形式表达。该方案简单、易实现,仿真算例验证了其有效性。     

带状态观测器系统的鲁棒容错控制

对具有不确定性参数的状态观在反馈系统,提出了传感器失效的鲁棒完整性控制方法,并对一定的二次性能指标具有最优性,设计方法简单、实用。     

攻击型无人机切换控制系统容错算法研究

攻击型无人机单侧发射或投放重型武器时,可将飞行控制系统看作是一个切换控制系统。针对常见的常值型和时变型两种执行器故障,提出了一种自适应观测器设计方法,同时结合状态反馈控制设计了容错控制器。通过Lyapunov函数推出了观测器的误差是关于故障界输入状态实际稳定的充分条件,通过平均驻留时间方法证明了切换控制系统是全局输入状态实际稳定的。某型攻击型无人机仿真实例表明,此方法能在准确估计故障大小的基础上,有效保持切换飞行控制系统的性能,应用前景十分广阔。     

基于径向基函数神经网络故障观测器的风能转换系统容错控制器设计

针对风能转换系统执行器部分失效故障,提出了一种新型的主动容错控制策略.应用径向基函数(radial basis function,RBF)自适应神经网络,根据系统状态观测值对执行器故障进行在线重构,基于该重构故障,设计滑模容错控制器切换增益,实现风能转换系统故障诊断与容错控制律在线整定,并进行稳定性证明.仿真结果表明,执行器发生故障时系统的功率系数和叶尖速比均能保持在最优值,从而实现额定风速以下的最大风能捕获.     

Observer-based controller for Lipschitz nonlinear systems

An observer-based controller for Lipschitz nonlinear systems is presented. The necessary and sufficient condition to ensure stability of state-observer as well as nonlinear system with state-feedback control law is derived. According to the separation principle, the closed-loop stability is guaranteed based on dual problems concerning stability of state-observer and stability of state-feedback parts. Also, the stability region for locally Lipschitz nonlinearities is obtained. A practical synthesis approach to achieve controller parameters is then given which yields the closed-loop convergence with less conservative results. The effectiveness of the proposed synthesis method is finally demonstrated by simulation results.     

Observer-based fault-tolerant control for a class of nonlinear networked control systems

This paper presents a fault-tolerant control (FTC) scheme for nonlinear systems which are connected in a networked control system. The nonlinear system is first transformed into two subsystems such that the unobservable part is affected by a fault and the observable part is unaffected. An observer is then designed which gives state estimates using a Luenberger observer and also estimates unknown parameter of the system; this helps in fault estimation. The FTC is applied in the presence of sampling due to the presence of a network in the loop. The controller gain is obtained using linear-quadratic regulator technique. The methodology is applied on a mechatronic system and the results show satisfactory performance.     

Observer-based adaptive output-constrained control design of switched stochastic nonlinear systems with input saturation

In this article, the problem of adaptive fuzzy control for output-constrained switched stochastic nonlinear systems subject to input saturation is addressed. By employing the trigonometric function mapping method, the constrained systems are transformed into unconstrained ones, and the control goals of the original constrained systems are not affected. Meanwhile, an auxiliary system is established to deal with the issue of input saturation, and an observer is constructed to estimate the unmeasured states. Then, the unknown nonlinear functions in the system are approximated by the fuzzy logic systems (FLSs). Based on the backstepping technique and Lyapunov function method, an output feedback control strategy is designed, where the dynamic surface control technique is applied in the backstepping design process to overcome the issue of a large number of online calculations. The designed controller can guarantee that all the signals of the system satisfy bounded conditions, and the output can track given reference signals within a small error range. Finally, a simulation example is given to verify the effectiveness of the proposed control scheme.     

一类非线性离散切换系统基于观测器的指数镇定

对一类离散非线性切换系统, 考虑了基于观测器的指数镇定问题. 借助微分中值定理(DMVT), 将非线性切换系统转化为线性参数(LPV)切换系统. 当状态变量不完全可获得时, 基于多Lyapunov函数方法, 给出系统在基于观测器的输出反馈控制器下指数镇定的充分条件. 所设计的滞后切换规则能够避免产生滑动模态. 并且将结果推广到系统方程含有不确定性的情况. 最后, 仿真例子说明了设计方法的有效性.     

Observer-based finite-time security fault-tolerant control for nonlinear multi-agent systems under byzantine adversaries

This article investigates the issue of security-based adaptive output feedback finite-time fault-tolerant control (FTC) for nonlinear multi-agent systems subjected to Byzantine attacks. In this work, the fuzzy logic systems are employed to approximate the unknown nonlinearities, and unmeasurable states are estimated by the designed state observer. In addition, a data selector is designed to detect extremely malicious data of the controlled system. Considering the actuator faults, a novel Nussbaum function is utilized to compensate for the uncertainties of attacks and intermittent failures. Then, by introducing first-order filter, an observer-based distributed adaptive output feedback finite-time security FTC algorithm is developed, which demonstrates all signals of the system are bounded, and the feasibility and effectiveness of the developed control scheme can be verified by simulation results.     

一类不确定非线性切换系统的鲁棒容错控制

研究一类不确定非线性切换系统的鲁棒容错控制问题,当执行器失效或部分失效时,利用Lyapunov函数法建立切换闭环系统混杂状态反馈容错控制器存在的充分条件;然后运用线性矩阵不等式将鲁棒容错控制器设计问题转化为一组线性矩阵不等式的可行解问题,从而借助Matlab中线性矩阵不等式工具箱求解;最后通过数值算倒验证了所提出设计方法的有效性.     

Observer-based adaptive FNN controller optimized by NAPSOSA for nonlinear time-delay systems

This study presents an observer-based adaptive fuzzy-neural network controller based on novel adaptive particle swarm optimization simulated annealing (NAPSOSA) for a class of uncertain nonlinear time-delay systems. Firstly, NAPSOSA is used to adjust the weighting function. Then, adaptive laws are adopted to approximate unknown nonlinear functions with unknown uncertainties, respectively. By examining the controller design, the observer-based control law and the weighting update law of the fuzzy-neural-network (FNN) controller are proposed for a class of nonlinear systems. In addition, based on strictly-positive-real (SPR) Lyapunov theory, the stabilization conditions for the closed-loop system are propounded. Furthermore, for obtaining a better performance, an algorithm consists of the adaptive FNN with NAPSOSA is presented to adjust the membership function of the controller. Finally, one simulation example is given to illustrate the effectiveness of the proposed approach.     

Observer-based robust H-infinity control for uncertain switched systems

The problem of observer-based robust H-infinity control is addressed for a class of linear discrete-time switched systems with time-varying norm-bounded uncertainties by using switched Lyapunov function method. None of the individual subsystems is assumed to be robustly H-infinity solvable. A novel switched Lypunov function matrix with diagonal-block form is devised to overcome the difficulties in designing switching laws. For robust H-infinity stability analysis, two linear-matrix-inequality-based sufficient conditions are derived by only using the smallest region function strategy if some parameters are preselected. Then, the robust H-infinity control synthesis is studied using a switching state feedback and an observer-based switching dynamical output feedback. All the switching laws are simultaneously constructively designed. Finally, a simulation example is given to illustrate the validity of the results.     

Correlation-based fault-tolerant controller design for MIMO systems under the Youla parameterisation

This paper develops a correlation-based method into the Youla parameterisation structure for a fault-tolerant controller design strategy. By tuning the Youla parameters with the proposed correlation-based algorithm, a number of conditional faults described by the dual Youla parameters are attenuated. The traditional fault-tolerant control (FTC) schemes under the Youla parameterisation often require the gradient information of the defined cost function for minimisation, which is either tedious or even unfeasible with unknown fault model. However, the proposed correlation-based FTC algorithm in this paper can compensate the faults via system data without the explicit fault model or the cost function gradient information. It is also proved that the algorithm convergence can be achieved without identifying the unknown fault model. For illustration, a simulation example with corresponding comparisons are presented to show the effectiveness of the proposed method in the end.