An integrated fault estimation and fault tolerant control method using H_∞‐based adaptive observers

Abstract

Summary An integrated fault estimation/fault‐tolerant control (FTC) scheme is developed in this article for nonlinear Lipschitz systems in the presence of external disturbances and actuator failures. To address this problem, coupled uncertainties between the observer error dynamics and the control system are considered, which is conveniently ignored in control approaches based on the separation principle. An H∞‐based adaptive observer is proposed to simultaneously estimate the system states and actuator faults without the restrictive strictly positive realness or persistent excitation conditions. The FTC is constructed by sliding mode control using the estimated states generated by the developed observer. A novel sufficient condition is derived in terms of linear matrix inequality (LMI) including both the system control dynamics and the estimation errors; then, the control parameters and observer gains are simultaneously obtained via solving the mentioned LMI based on the H∞ optimization. Finally, a flexible joint robot is considered to illustrate the effectiveness of the developed method.

Distributed output estimation error observer‐based adaptive fault‐tolerant consensus tracking control of multi‐agent systems

“…Remark Compared with the existing adaptive observers, 25,32 the restriction mentioned in () is convenient. According to Assumption 1, in the work of Raoufi et al, 36 it is indicated that the equality $$$ PE={C}^TR $$$ is satisfied if and only if $$$ \mathit{\operatorname{rank}}(CE)=\mathit{\operatorname{rank}}(E) $$$.…”

“…The fixed‐time tracking consensus problem of high‐order nonlinear MASs with actuator faults and performance constraint is investigated in the work of Yang et al 23 A new distributed fault‐tolerant control scheme based on the static output feedback for interconnected systems is developed by Zhang et al Based on the associated information, a distributed fault estimator can improve the accuracy of fault estimation information 24 . In the work of Fazeli and Abedi, 25 an integrated fault estimation and fault‐tolerant control scheme is proposed for the nonlinear Lipschitz systems with external disturbances and actuator faults. The designed observer‐based distributed fault‐tolerant consensus tracking control (D‐FTCTC) scheme with a distributed fashion can ensure an effective compensation and tolerance for actuator faults of Lipschitz nonlinear MASs, while achieving the state consensus tracking target.…”

Fuzzy adaptive observer‐based fault estimation design with adjustable parameter for satellite under unknown actuator faults and perturbations

“…In [24], actuator faults, external disturbances, and uncertain inertia parameter of a rigid spacecraft are regard as a lumped disturbance together, which is estimated via a finite‐time disturbance observer. Considering the coupling effect between the observer error dynamics and the control system, an $${H_\infty }$$ based adaptive observer is developed for nonlinear Lipschitz systems in the presence of external disturbances and actuator faults [25]. More results on the fault diagnosis including the quantitative and qualitative methods for continuous‐time systems and discrete‐time systems can be found in [26].…”

Adaptive fault‐tolerant tracking control for nonlinear systems with unknown control coefficient and input saturation

“…Hence, it is of great significance to study the fault-tolerant control under the actuator fault. [15][16][17][18][19] On the other hand, the prior information of the control coefficient is required in most literature, while it is difficult to detect in some cases. [20][21][22] Therefore, it is more reasonable to study the case that the control coefficient is unknown.…”

“…Deviations in the characteristics of the control input signal can cause the actuator fault, which reduces the safety and reliability of system. Hence, it is of great significance to study the fault‐tolerant control under the actuator fault 15‐19 . On the other hand, the prior information of the control coefficient is required in most literature, while it is difficult to detect in some cases 20‐22 .…”