多输入多输出最小相位系统的执行器故障自适应容错控制

针对一类具有执行器卡死或/和变执行器故障的多输入多输出(MIMO)非线性最小相位系统提出了自适应容错跟踪控制方案.结合系统特征对系统执行器进行分类,用神经网络逼近执行器未知故障函数,采用模型参考自适应容错控制方法设计控制律.所设计的控制律不仅保证闭环系统稳定,而且跟踪误差一致最终有界.仿真结果表明了所提出方法的有效性.     

执行器故障不确定非线性系统最优自适应输出跟踪控制

本文针对一类具有执行器故障的多输入多输出（Multi-input multi-output,MIMO）不确定连续仿射非线性系统,提出了一种最优自适应输出跟踪控制方案.设计了保证系统稳定性的不确定项估计神经网络权值调整算法,仅采用评价网络即可同时获得无限时域代价函数和满足哈密顿-雅可比-贝尔曼（Hamilton-Jacobi-Bellman,HJB）方程的最优控制输入.考虑执行器卡死和部分失效故障,设计最优自适应补偿控制律,所设计的控制律可以实现对参考输出的一致最终有界跟踪.飞行器控制仿真和对比验证表明了本文方法的有效性和优越性.     

非线性动态突变系统的多模型自适应执行器故障补偿设计

本文针对因多重不确定执行器故障而引起系统动态突变的非线性系统, 设计了一种基于多模型切换的自适应执行器故障补偿控制策略, 以提高系统应对动态突变的能力, 同时实现不确定执行器故障的快速精确补偿. 针对执行器故障模式的不确定性问题, 采用基于多模型的参数估计方法, 设计了自适应控制器组; 基于最优性能指标函数, 提出了一种控制切换机制, 以选择最佳的自适应控制器作为当前的控制器, 从而实现期望的故障补偿控制. 所设计的多模型自适应控制策略, 可以保证所有闭环系统信号有界, 且在出现有限数量的不确定性执行器故障情况下, 系统输出渐近跟踪所选择的参考系统输出; 同时, 当系统中出现持续间歇性执行器故障时, 此方法可以保证系统的输出跟踪误差是平均小的. 最后, 本文基于飞行器动力学模型, 进行仿真研究, 验证了所设计的自适应故障补偿策略的有效性.     

飞翼飞行器的操纵面故障自适应补偿控制

本文针对具有操纵面卡死、失效故障以及执行器饱和的飞翼飞行器纵向运动,考虑系统的预定动态性能,提出了一种自适应反步补偿跟踪控制方案.设计预定动态性能(prescribed performance bound,PPB)边界以保证系统的跟踪误差,采用二阶指令滤波器限制执行器的饱和,通过控制分配避免执行器故障后对横侧向运动的影响.所设计的自适应反步补偿跟踪控制律能够保证系统对参考信号的渐近跟踪.仿真结果表明了本文方法的有效性.     

双电机同步驱动伺服系统故障诊断与容错控制

本文针对双电机同步驱动伺服系统中执行器失效会导致系统性能下降甚至失稳的情况,提出了一种基于自适应滑模的故障诊断和容错控制策略.该方法通过设计各电机转速的自适应滑模状态观测器,在线估计各执行器的失效因子:当单个执行器部分失效时,通过自适应的方法调整控制器增益;当单个执行器全部失效时,重构系统的控制律.对于系统中存在非匹配不确定项的情况,提出在期望虚拟信号中引入基于扩张状态观测器的补偿项抑制方案;利用Lyapunov理论证明了闭环系统在正常和故障状况下的稳定性以及观测器的收敛性;仿真结果表明,所设计的控制策略能保证系统稳定跟踪指令信号,在单个执行器失效的情况下系统跟踪性能基本不下降.     

一类MISO 最小相位系统的执行器故障自适应容错控制

针对一类具有执行器卡死或/和变执行器故障的多输入单输出(MISO)非线性最小相位系统,提出一种自适应容错跟踪控制方案.采用自适应算法估计系统的不确定性,利用神经网络逼近执行器未知故障函数,以完成执行器组合故障状态下的跟踪控制.所设计的控制律不仅保证了闭环系统稳定,而且所有状态均有界,跟踪误差一致最终有界.仿真结果表明了所提出方法的有效性.     

航天器位姿运动一体化直接自适应容错控制研究

针对航天器近距离操作过程中追踪航天器位姿控制系统执行器故障问题, 提出了一种直接自适应容错控制方法, 保证了追踪航天器在发生执行器故障下的自身稳定性和对目标航天器位姿状态的渐近跟踪性能. 基于对偶四元数的航天器位姿一体化控制系统模型, 首先, 假设故障已知, 设计标称控制信号; 然后, 设计自适应更新律对标称控制信号中的未知参数进行估计, 构成自适应控制信号; 最后, 利用多Lyapunov函数对多故障模式下的系统性能进行分析. 仿真结果表明了所提方法的有效性.     

未知仿射非线性系统的执行器容错控制设计

针对一类多输入单输出未知仿射非线性系统研究了在执行器发生故障情况下的容错控制问题,基于反步设计和自适应模糊逼近理论给出了控制方案使闭环系统能够同时容忍执行器的卡死和失效故障。在每一步设计中采用一个模糊逼近器来逼近未知函数,其中包括系统函数和由故障引起的未知动态。然后基于Lyapunov稳定性理论设计自适应律在线调节逼近器的参数,使其可以自动补偿故障对系统的影响。最终得到的控制器能够在执行器发生卡死和失效故障的情况下利用未卡死执行器的有效部分保证闭环系统是稳定的,并且输出能够以指定的精度跟踪给定参考信号。仿真算例证实了该方法的可行性和有效性。     

考虑有执行器故障和有界扰动的鲁棒自适应容错补偿控制

考虑在执行器故障和外界干扰下, 用直接自适应状态反馈控制策略解决线性时不变连续时间系统的鲁棒容错补偿控制问题. 提出更一般且更实际的执行器故障模型. 在执行器故障和扰动的上界都未知下, 提出自适应律在线估计未知控制器参数. 然后基于自适应策略的信息, 构造一类鲁棒自适应状态反馈控制器自动补偿故障和扰动的影响. 基于李亚普诺夫定理, 在执行器故障和干扰下, 所得的自适应闭环系统可以被保证渐进稳定. 最后给出一个火箭整流罩模型的例子和它的仿真结果.     

虚假数据注入攻击下多无人机韧性容错协同控制

针对同时具有虚假数据注入(false data injection, FDI)攻击与执行器故障下的多无人系统编队协同跟踪问题,提出了一种基于FDI攻击检测机制与故障观测器的韧性容错协同控制新方法。首先,以二阶非线性固定翼无人机模型作为多无人系统研究对象;其次,构建了带有概率约束的贝叶斯概率检测模型对FDI攻击进行检测,作为韧性容错协同控制器的辅助系统;之后,设计了包含执行器故障补偿的韧性容错协同跟踪控制器,并利用Lyapunov稳定性理论证明系统的渐进稳定;最后,通过仿真验证了设计的控制器针对FDI攻击与执行器故障的安全性与可靠性以及编队跟踪能力。     

Virtual Grouping based adaptive actuator failure compensation for MIMO nonlinear systems

A new control design technique called virtual grouping is presented to handle actuator redundancy and failures for multiple-input-mutliple-output (MIMO) systems, enlarging the set of compensable actuator failures. An adaptive compensation scheme is thus developed for a class of nonlinear MIMO systems to ensure closed-loop signal boundedness and asymptotic output tracking despite unknown actuator failures. Simulation results are given to show the effectiveness of the adaptive design.     

Adaptive actuator failure compensation for nonlinear MIMO systems with an aircraft control application

A direct adaptive approach is developed for control of a class of multi-input multi-output (MIMO) nonlinear systems in the presence of uncertain failures of redundant actuators. An adaptive failure compensation controller is designed which is capable of accommodating uncertainties in actuator failure time instants, values and patterns. A realistic situation is studied with fixed grouping of actuators and proportional actuation within actuator groups. The adaptive control system is analyzed, to show its desired stability and asymptotic tracking properties in the presence of actuator failure uncertainties. As an application, such an adaptive controller is used for actuator failure compensation of a twin otter aircraft longitudinal model, with design conditions verified and control structure and adaptive laws developed for a nonlinear aircraft dynamic model. The effectiveness of adaptive failure compensation is demonstrated by simulation results.     

Adaptive compensation control for special actuator circumstances with input quantization

In this article, considering actuator constraints and possible failures, an adaptive compensation control scheme is developed to realize tracking control for a class of uncertain nonlinear systems with quantized inputs. A new variable is generated to evaluate the effect of actuator saturation and is used in the process of controller design to compensate for the influence of actuator saturation constraint. Moreover, the controller is able to show certain accommodation capability to tolerate possible actuator failures and input quantization error via integrating parameter update process of unknown fault constants into adaption of parametric uncertainties under the backstepping procedure. Specifically, actuator saturation effect and possible actuator failures as well as input quantization error can be dealt with uniformly under the framework of the proposed scheme and the control system has certain robustness to external disturbances. It is proved that all the signals of the closed‐loop system are ensured to be bounded and the tracking error is enabled to converge toward a compact set, which is adjustable by tuning design parameters. Finally, experiments are carried out on an active suspension plant to illustrate the effectiveness of the proposed control scheme.     

A discrete-time parameter estimation based adaptive actuator failure compensation control scheme

This article studies discrete-time adaptive failure compensation control of systems with uncertain actuator failures, using an indirect adaptive control method. A discrete-time model of a continuous-time linear system with actuator failures is derived and its key features are clarified. A new discrete-time adaptive actuator failure compensation control scheme is developed, which consists of a total parametrisation of the system with parameter and failure uncertainties, a stable adaptive parameter estimation algorithm, and an on-line design procedure for feedback control. This work provides a new design of direct adaptive compensation of uncertain actuator failures, using an indirect adaptive control method. Such an adaptive design ensures desired closed-loop system stability and tracking properties despite uncertain actuator failures. Simulation results are presented to show the desired adaptive actuator failure compensation performance.     

Adaptive actuator failure compensation for multivariable feedback linearizable systems

A feedback linearization‐based adaptive control scheme is developed for multivariable nonlinear systems with redundant actuators subject to uncertain failures. Such an adaptive controller contains a direct adaptive actuator failure compensator to compensate the uncertain actuator failure, a nonlinear feedback to linearize the nonlinear dynamics, and a linear feedback to stabilize the linearized system. The key new design feature is the estimation of both the failure patterns and the failure values, for direct adaptive actuator failure compensation, newly developed for multivariable feedback linearizable nonlinear systems. With direct control signal adaptation, the adaptive failure compensation design ensures closed‐loop stability and asymptotic output tracking in the presence of actuator failure uncertainties. Simulation results from an application to attitude control of a near‐space vehicle dynamic model are presented to verify the desired system performance with adaptive actuator failure compensation. Copyright © 2015 John Wiley & Sons, Ltd.     

Adaptive inverse control for parametric strict feedback systems with unknown failures of hysteretic actuators

An adaptive compensation control scheme is proposed by using backstepping techniques for a class of uncertain nonlinear systems preceded by m hysteretic actuators, which exhibit unknown backlash nonlinearity and possibly experience unknown failures. An estimated smooth inverse of the actuator backlash is utilized in the controller design to compensate for the effects of the backlash and actuator failures. It is shown that the designed controllers can ensure all signals of closed‐loop system bounded for any failure pattern of hysteretic actuators and tracking performance is also maintained. Simulation studies confirm the effectiveness of the proposed controller, especially the improvement of system performances. Copyright © 2013 John Wiley & Sons, Ltd.