This paper proposes synthesis algorithms for the design of passive state- and output-feedback fault-tolerant controllers. Sufficient conditions for the existence and the construction of such fault-tolerant controllers are given in terms of linear matrix inequalities (LMIs) which can be solved efficiently. The state-feedback fault-tolerant controller consists of a family of state-feedback gains switched appropriately according to a stabilizing switching signal so that the closed-loop system satisfies a performance requirement expressed in terms of system L2 norm. Similarly, the output feedback controller consists of a family of full-order linear, time-invariant controllers switched according to a stabilizing signal that depends only on the controller states. Both approaches are passive in the sense that they do not rely on the detection and/or the estimation of the faults. The proposed approaches are tested on a nonlinear model of a quadcopter. Simulation results show that satisfactory stability, tracking, and disturbance rejection are maintained despite of time-varying actuator faults.

Automatic voltage regulators (AVRs) play a vital role in maintaining voltage stability and improving the overall reliability of power systems. However, they are frequently affected by load fluctuations, steady-state faults, and oscillatory transient responses, which degrade voltage regulation performance. Conventional control strategies struggle to adequately address these challenges, as they often exhibit limited robustness and insufficient dynamic performance under varying operating conditions. To overcome these limitations, this paper proposes a fractional-order PID controller with double derivative (FOPIDD ² ), optimized using a novel triple-hybrid metaheuristic algorithm known as FGWO-WaOA-NM. The proposed fusion algorithm leverages gray wolf optimizer (GWO) to enhance the exploration capability of walrus optimization algorithm (WaOA), while Nelder–Mead (NM) is incorporated to refine local exploitation. The robustness and effectiveness of the proposed optimization framework are first validated using complex benchmark problems from the CEC2019 test suite. The performance of FGWO-WaOA-NM is benchmarked against cutting-edge algorithms, such as gray wolf, walrus, whale, reptile search, zebra, tunicate swarm, seagull, and prairie dog optimizations. Results demonstrate that FGWO-WaOA-NM consistently achieves superior solution quality and faster convergence. A comprehensive comparative analysis is conducted against various controllers, including PID, FOPID, PIDD ² and FOPIDD ² optimized using advanced algorithms to validate the effectiveness of the proposed control scheme. The proposed FGWO-WaOA-NM-optimized FOPIDD ² controller demonstrates faster convergence, enhanced robustness, reduced overshoot, and improved transient performance, confirming its suitability for modern AVR applications.

Suspension systems in vehicles are crucial to both ride quality and driving security. The challenge of creating an effective control mechanism for automotive active suspension systems is addressed in this work. In the event of unforeseen road disturbances, the active suspension systems are intended to deliver a more pleasant ride and good handling. Fuzzy-Linear Quadratic Gaussian (FLQG) and Fuzzy-Linear Quadratic Regulator (FLQR) controllers adapting to road disturbances are proposed to enhance vehicle comfort through the reduction of the driver's overall body acceleration. The simulation findings demonstrate that the FLQR and FLQG controllers are efficient in adjusting the automotive suspension configuration under varying road profiles compared to those of the conventional LQR and LQG controllers.

This article addresses the challenge of integrated switched H2 control with disturbance rejection capabilities for switched systems, particularly when external disturbances are present. A novel anti-disturbance switched H2 control strategy is formulated, leveraging estimated disturbance values. The formulation is given in Linear Matrix Inequalities (LMIs), establishing sufficient conditions to ensure H2 performance while maintaining closed-loop stability. To validate the effectiveness of the proposed methodology, it is applied to a practical aero-engine model. Through simulations, it is demonstrated that the closed-loop aero-engine model exhibits remarkable transient performance even in the face of external disturbances. These results underscore the efficacy of the developed approach in enhancing the robustness and performance of switched systems subjected to disturbances. The integration of anti-disturbance capabilities within the H2 control framework offers a promising avenue for addressing real-world control challenges, particularly in systems characterized by switching dynamics and external perturbations.

Pamukkale University Journal of Engineering Sciences