In this paper, a robust fault estimation approach is proposed for multi-input and multioutput nonlinear dynamic systems on the basis of back propagation neural networks. The augmented system approach, input-to-state stability theory, linear matrix inequality optimization, and neural network training/learning are integrated so that a robust simultaneous estimate of system states and actuator faults are achieved. The proposed approaches are finally applied to a 4.8 MW wind turbine benchmark system, and the effectiveness is well demonstrated.

Diagnosing potential faults is of great importance to ensure reliability of battery management systems. This is because a current or voltage sensor fault often results in an inaccurate state-of-charge estimate. A temperature sensor fault will cause abnormal thermal management. A battery internal resistance (BIR) fault can lead to an increase in energy and power losses, capacity fading, and further degradation of health. In addition, frequent data transmission to fault diagnosis unit will cause a great waste of communication resources. To this end, a combined model-based and data-driven fault diagnosis scheme for lithium-ion batteries is proposed in this article. First, a model-based fault estimation method with sliding mode observer is developed to estimate the voltage, current, and temperature sensor faults. By integrating an adaptive event-triggered mechanism, the communication resource costs are alleviated. Second, a data-driven gap metric approach is presented to detect the BIR fault. By combining the model-based and data-driven strategies, the fault diagnosis logic is put forward to isolate the BIR fault. Finally, several experiments of the single cell and the battery pack are conducted to verify the effectiveness and superiority of the developed method over the existing results.

In response to the high demand of the operation reliability and predictive maintenance, health monitoring and fault diagnosis and classification have been paramount for complex industrial systems (e.g., wind turbine energy systems). In this study, data-driven fault diagnosis and fault classification strategies are addressed for wind turbine energy systems under various faulty scenarios. A novel algorithm is addressed by integrating fast Fourier transform and uncorrelated multi-linear principal component analysis techniques in order to achieve effective three-dimensional space visualization for fault diagnosis and classification under a variety of actuator and sensor faulty scenarios in 4.8 MW wind turbine benchmark systems. Moreover, comparison studies are implemented by using multi-linear principal component analysis with and without fast Fourier transform, and uncorrelated multi-linear principal component analysis with and without fast Fourier transformation data pre-processing, respectively. The effectiveness of the proposed algorithm is demonstrated and validated via the wind turbine benchmark.

Unexpected faults in actuators and sensors may degrade the reliability and safety of aero engineering systems. Therefore, it is motivated to develop integrated fault tolerant control techniques with applications to aero engineering systems. In this paper, discrete-time dynamic systems, in presence of simultaneous actuator/sensor faults, partially decoupled unknown input disturbances, and sensor noises, are investigated. A jointly state/fault estimator is formulated by integrating unknown input observer, augmented system approach, and optimization algorithm. Unknown input disturbances can be either decoupled by unknown input observer, or attenuated by linear matrix inequality optimization, enabling the estimation error to be input-to-state stable. Estimator-based signal compensation is then implemented to mitigate adverse effects from unanticipated actuator and sensor faults. A pre-designed controller, which maintains normal system behaviors under fault-free scenario, is allowed to work along with the presented fault tolerant mechanism of the signal compensations. The fault-tolerant closed-loop system can be ensured to mitigate the effects from the faults, guarantee the input-to-state stability, and satisfy the required robustness performance. The proposed fault estimation and fault tolerant control methods are developed for both discrete-time linear and discrete-time Lipschitz nonlinear systems. Finally, the proposed techniques are applied to a jet engine system and a flight control system for simulation validation.

In fault-diagnosis classification, a pressing issue is the lack of target-fault samples. Obtaining fault data requires a great amount of time, energy and financial resources. These factors affect the accuracy of diagnosis. To address this problem, a novel fault-diagnosis-classification optimization method, namely TLSCA-SVM, which combines the sine cosine algorithm and support vector machine (SCA-SVM) with transfer learning, is proposed here. Considering the availability of fault data, this thesis uses the data generated by analog circuits from different faults for analysis. Firstly, the data signal is collected from different faults of the analog circuit, and then the characteristic data are extracted from the data signals by the wavelet packets. Secondly, to employ the principal component analysis (PCA) reduces the feature-value dimension. Lastly, as an auxiliary condition, the error-penalty item is added to the objective function of the SCA-SVM classifier to construct an innovative fault-diagnosis model namely TLSCA-SVM. Among them, the Sallen–Key bandpass filter circuit and the CSTV filter circuit are used to provide the data for horizontal- and vertical-contrast classification results. Comparing the SCA with the five optimization algorithms, it is concluded that the performance of SCA optimization parameters has certain advantages in the classification accuracy and speed. Additionally, to prove the superiority of the SCA-SVM classification algorithm, the five classification algorithms are compared with the SCA-SVM algorithm. Simulation results showed that the SCA-SVM classification has higher precision and a faster response time compared to the others. After adding the error penalty term to SCA-SVM, TLSCA-SVM requires fewer fault samples to process fault diagnosis. Ultimately, the method which is proposed could not only perform fault diagnosis effectively and quickly, but also could run effectively to achieve the effect of transfer learning in the case of less failure data.

Emerging multisource data provide a promising way to make breakthroughs in remaining useful life prediction. Due to the diversity in industrial sites and the complexity of the engineering systems, a large amount of degradation information of machinery is hidden in multitype data, which poses a challenge to adequately capture the complex features that jointly affect remaining useful life. To this end, we propose an interactive attention-based deep spatio-temporal network to effectively fuse vibration waveforms and time-varying operating signals. Specifically, the spatio-temporal structure in the proposed model has the ability to mine long-term dependence and local spatial information from raw multisource data simultaneously. An interactive attention mechanism is used to weight the extracted feature contributions from different source dynamically. Furthermore, a modified mean absolute percentage error criterion is designed in the training process for the inherent properties of the remaining useful prediction. For illustration, a case study of a rotating machinery in an oil refinery and a public dataset of an aircraft engine are investigated. The extensive experiments have demonstrated that, compared to relying solely on either vibrational or operating signals and different fusion strategies, the proposed model can effectively integrate multisource data to reduce prediction loss with an acceptable performance.