【作者】 何静；

【导师】 邱静；

【作者基本信息】 国防科学技术大学 ， 机械工程， 2009， 博士

【摘要】 控制系统的状态监控、故障诊断与容错控制一直是理论和工程实际应用中重点关注和迫切需要解决的关键问题之一。基于系统解析模型并结合现代控制理论与方法的故障诊断技术是一种在控制系统中广泛应用的方法。然而,非线性、建模误差和未知输入扰动等因素的存在,使其在工程实际中的应用带来了很大的局限性。论文在国家自然科学基金和部委级预先研究项目的支持下,围绕着将基于解析模型的状态观测器方法对系统参数的估计能力与滑模变结构控制理论对外部扰动的不变性有机结合这一核心,从提高故障检测的鲁棒性,提高执行器、传感器故障的诊断能力,提高微弱故障、缓慢变化故障等的诊断精度以及在故障诊断系统中实现容错控制功能等几个方面着手,对不确定非线性系统鲁棒故障检测与重构技术进行了较系统和深入的研究。论文的主要研究工作与结论如下:在深入调研当前理论与技术发展现状的基础上,归纳总结了该领域研究的特点和存在的问题。指出鲁棒故障检测与重构方法是提高故障诊断系统性能指标的有效方式,是解决基于观测器的非线性系统故障诊断方法实际应用问题的有效途径。针对残差生成故障检测方法中检测鲁棒性与灵敏度相矛盾的问题,提出基于滑模观测器的非线性系统鲁棒残差生成与故障检测方法。设计滑模观测器以生成残差,利用滑模变结构对未知输入扰动具有的不变性抑制扰动对残差信号的影响,从而提高系统对故障信号的灵敏度。将该方法加以推广,通过为系统中每种故障模型设计相应的滑模观测器以实现多个故障的检测与隔离。检测鲁棒性与灵敏度之间矛盾的解决也为后续故障重构技术的实现奠定了基础。针对机电系统中常见的仿射非线性系统执行器故障诊断问题,提出了鲁棒故障重构与容错控制集成设计方法。利用滑模观测器克服未知输入扰动对控制系统的影响并实现鲁棒状态观测,利用自适应观测器从模型不确定的系统中分离并重构故障,而所采用的观测器设计方法又自然地确保系统的控制状态不受故障影响,从而实现了集成故障重构和容错控制的系统功能。非线性系统中,传感器的故障诊断远远落后于执行器的故障诊断,且大多数方法难以满足工程实际应用的需要。为此,针对非线性系统传感器故障诊断的难题提出了基于等效变换的传感器鲁棒故障重构与容错控制集成设计方法。利用一阶滤波器将传感器故障等效变换为虚拟的执行器故障,并首次从能观性出发提出滤波器参数选取的理论依据。在此基础上,针对正则型非线性系统提出了集成容错控制功能的传感器鲁棒故障重构方法,该方法在确保系统鲁棒性的前提下对缓变故障也具有较高的灵敏度;针对一般非线性系统提出了考虑前向通道和反馈通道同时含有未知输入扰动的增强型传感器鲁棒故障重构算法,较之其它方法更加良好的工程实用性是该算法的突出特点。针对由于故障和未知输入扰动的相关性而使故障重构的精确性与鲁棒性之间产生矛盾的问题,利用滑模观测器和滑模变结构等值原理,提出了基于干扰解耦技术的精确故障重构方法。为解决系统既要对未知输入扰动不敏感,又要能精确重构出尽可能小的故障的所谓鲁棒故障重构问题,基于微分同胚变换提出不需对系统输出求导的多故障重构算法,较大程度地提高了算法的工程实用性;基于线性坐标变换,提出了故障与扰动完全解耦的精确重构方法,可在对故障精确重构的同时实现对未知输入扰动的精确重构;提出了通过消除滑模抖振对故障重构机制的影响,进一步提高了重构算法对故障的灵敏度,从而实现了微弱缓变故障的鲁棒重构。结合机电跟踪与稳定伺服平台的系统特点和工程需求,对所提出的不确定非线性系统中的鲁棒故障检测与重构技术进行了应用研究。针对平台中直流伺服电机控制系统设计了基于滑模观测器的故障重构与容错控制方法,实验研究结果显示本文的理论与技术正确有效。论文的研究对于非线性系统的故障诊断与重构技术研究具有重要的参考价值,填补和拓展了其理论方法、技术手段和应用范围,具有较好的学术价值与工程应用价值。更多还原

【Abstract】 State monitoring, fault diagnosis and fault-tolerant control have drawn great public interest and been a key problem to be solved in theories and engineering application of control systems. The fault diagnosis technology based on a combination of the analytic model of system and modern control theories and methodologies is widely applied in control systems. Factors such as nonlinearity, modeling errors and unknown input disturbance, etc., however, have greatly limited the application of such technologies. Granted by the Natural Science Foundation of China and the Ministerial-level Preparatory Research Project, a systematic and deep investigation is done in this paper on the robust fault diagnosis and reconstructing technologies of uncertain nonlinear systems, focusing on the integration of parameters estimation capability of state observation based on analytic model and the invariance to external disturbance of the sliding mode variable structure control theory, so as to increase the fault diagnosis robustness, the diagnosis capacity of the actuator faults and sensor faults, the diagnosis accuracy for weak and incipient faults, and to achieve fault-tolerant control in fault diagnosis systems.The major contents and conclusions can be summarized as follows:The features and existing problems in this field are investigated and summarized after an in-depth survey of current theories and technological development. It is proposed that robust fault diagnosis and reconstruction method is effective to improve the performance indices of fault diagnosis system and solve the application problems in observer-based fault diagnosis for mechatronic nonlinear systems.For the contradiction between robustness and sensitivity of diagnosis found in the residual generation fault diagnosis of nonlinear systems, a robust residual generation fault diagnosis based on a sliding mode observer is proposed, in which the sliding observer is designed to generate residues and the invariance of the sliding mode variable structure to unknown input disturbance is used to control the influence of disturbance on residue signals so that sensitivity of the systems to faults can be increased. An extension of this method is made by designing correspondent sliding mode observers for each fault type so as to realize multiple faults detection and isolation. The resolution of the contradiction between diagnosis robustness and sensitivity has laid a good foundation for the fault reconstruction mentioned in subsequent chapters.For the actuator fault diagnosis of the common affine nonlinear systems, a synthetic design is proposed to realize robust fault diagnosis and tolerant control. The sliding mode observer is used to decrease the influence of unknown input disturbance on the control system and realize robust state observation, the adaptive observer is used to separate and reconstruct faults for model uncertain systems, and the design of observers adopted naturally prevents the controlling states of system from being affected by faults, all of which guarantee the realization of a synthetic function of fault reconstruction and tolerant control.The research on sensor fault diagnosis for nonlinear systems is lagging far behind that on actuator fault diagnosis and most of the methodologies adopted cannot satisfy the needs in practice. For this case a synthetic design is made to realize robust fault reconstruction and tolerant control on the basis of the equivalent transformation between two different fault types. The first-order filter transfroms the sensor faults equivalently into virtual actuator faults. The parameter selecting principle for the filter is for the first time approached from the perspective of observability of system. Then, a robust fault tolerant control and reconstructing method is proposed for sensors faults of normal form nonlinear systems, which guarantees a considerably high sensitivity to incipient faults as well as the robustness of system. An enhanced sensor fault reconstructing algorithm is put forward for general nonlinear systems, in which unknown input disturbance is involved in both the forward channel and the feedback channel. A typical feature of this algorithm is its improved engineering practicability.For the contradiction between fault reconstruction accuracy and its robustness arising from the correlations between unknown input disturbance and faults, a precisely fault reconstructing method is proposed by using the disturbance decoupling technology concerning the sliding mode observer and the equivalence theory of sliding mode variable structure. To guarantee the insensitivity of the system to unknown input disturbance and the precise reconstruction of the weakest fault, that is, to realize robust fault reconstruction, a multiple faults reconstructing algorithm is achieved on the basis of diffeomorphism coordinate transformation, where the derivatives need not be calculated and the applicability greatly improved. On the basis of linear coordinate transformation, a precisely reconstructing method for of is constructed, where the faults and unknown input disturbances are completely decoupled and the precise reconstruction of them can be respectively achieved. It is also proposed that the sensitivity to the faults can be improved by eliminating the effects of sliding mode chattering on fault signals and that weak and incipient faults can be robustly reconstructed.Application study is carried out on the proposed robust fault detecting and reconstructing technology used in uncertain mechatronic nonlinear systems with a consideration of both engineering requirements and the system features of mechatronic tracking and steadying servo platform. For the DC servomotor control system on the platform, a fault reconstructing and tolerant control program based on slide mode observer is designed. Experimental results indicate the correctness and efficiency of the theories and technologies proposed in this paper.Research done in this paper has filled in and expanded the theories, technologies and application scope of fault diagnosing and reconstructing technologies for nonlinear systems, which will be of great value both academically and practically.更多还原