Integrated fault estimation and fault-tolerant control for stochastic systems with Brownian motions

This paper presents an integrated robust fault estimation and fault‐tolerant control technique for stochastic systems subjected to Brownian parameter perturbations. The augmented system approach, unknown input observer method, and optimization technique are integrated to achieve robust simultaneous estimates of the system states and the means of faults concerned. Meanwhile, a robust fault‐tolerant control strategy is developed by using actuator and sensor signal compensation techniques. Stochastic linear time‐invariant systems, stochastic systems with Lipschitz nonlinear constraint, and stochastic systems with quadratic inner‐bounded nonlinear constraint are respectively investigated, and the corresponding fault‐tolerant control algorithms are addressed. Finally, the effectiveness of the proposed fault‐tolerant control techniques is demonstrated via the drivetrain system of a 4.8 MW benchmark wind turbine, a 3‐tank system, and a numerical nonlinear model

Interval observer-based fault detectability analysis using mixed set-invariance theory and sensitivity analysis approach

This is an Accepted Manuscript of an article published by Taylor & Francis in “International Journal of Systems Science” on 06th January 2019, available online: https://www.tandfonline.com/doi/abs/10.1080/00207721.2018.1563221?journalCode=tsys20This paper addresses the characterization of the minimum detectable fault (MDF) by means of residual sensitivity integrated with the set-invariance theory when using an interval observer-based approach as a Fault Detection (FD) scheme. Uncertainties (disturbances and noise) are considered as of unknown but bounded nature (i.e., in the set-membership framework). A zonotopic-set representation towards reducing set operations to simple matrix calculations is utilized to bound the state/output estimations provided by the interval observer-based approach. In order to show the connection between sensitivity and set-invariance analyses, mathematical expressions of the MDF are derived when considering dierent types of faults. Finally, a simulation case study based on a quadruple-tank system is employed to both illustrate and discuss the effectiveness of the proposed approach. Interval observer-based FD scheme is used to test the MDF obtained from the integration of both residual sensitivity analysis and set-invariance theory in the considered case study.Peer ReviewedPostprint (author's final draft