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        Hierarchical adaptive control of selfstabilizing electromechanical systems using artificial-immune self-tuning mechanism for state weighting-factors

        Omer Saleem,Khalid Mahmood-ul-Hasan 대한기계학회 2021 JOURNAL OF MECHANICAL SCIENCE AND TECHNOLOGY Vol.35 No.3

        This article presents a novel self-adaptive linear-quadratic-regulator (LQR) architecture to improve the robustness of self-stabilizing electromechanical systems against exogenous disturbances. The main contribution of this article is to formulate a nonlinear-type artificial-immune adaptation mechanism that dynamically adjusts the state-weighting-factors of LQR’s quadratic-performance-index online. The Riccati-equation solver uses these updated state-weighting-factors to yield time-varying state-feedback gains. This hierarchical control procedure uses immunological computations to indirectly alter the LQR gains, which helps in flexibly reconfiguring the control trajectory under disturbances. The performance of the proposed immune-adaptive LQR is benchmarked against a conventional adaptive LQR and a fixed-gain LQR by conducting software simulations on the nominal model of the QNET rotary pendulum system. Credible real-time experiments are also conducted on the QNET rotary pendulum’s hardware setup to analyze each controller’s efficacy in the physical environment. The simulation and experimental results validate the superior disturbance-rejection capability of the proposed controller under every testing scenario.

      • KCI등재

        Adaptive State-space Control of Under-actuated Systems Using Error-magnitude Dependent Self-tuning of Cost Weighting-factors

        Omer Saleem,Khalid Mahmood-ul-Hasan 제어·로봇·시스템학회 2021 International Journal of Control, Automation, and Vol.19 No.2

        This article methodically constructs a novel adaptive self-tuning state-space controller that enhances the robustness of under-actuated systems against bounded exogenous disturbances. The generic Linear-Quadratic-Regulator (LQR) is employed as the baseline controller. The main contribution of this article is the formulation of a hierarchical online gain-adjustment mechanism that adaptively modulates the weighting-factors of LQR’s quadratic-performance-index by using pre-calibrated continuous hyperbolic scaling functions. The hyperbolic scaling functions are driven by the magnitude of system’s state-error variables. This augmentation dynamically updates the solution of the Matrix-Riccati-Equation which modifies the state-feedback gains after every sampling interval. The efficacy of the proposed adaptive controller is validated by conducting hardware-in-the-loop experiments on QNET Rotary Pendulum setup. The experimental outcomes show that the proposed adaptive control schemeyields stronger damping against oscillations and faster error-convergence rate, while maintaining the controller’s asymptotic-stability, under the influence of parametric uncertainties.

      • KCI등재

        Unified Fault-Tolerant Control for Air-Fuel Ratio Control of Internal Combustion Engines with Advanced Analytical and Hardware Redundancies

        Amin Arslan Ahmed,Mahmood-ul-Hasan Khalid 대한전기학회 2022 Journal of Electrical Engineering & Technology Vol.17 No.3

        This paper proposes a Unifi ed Fault-Tolerant Control System (UFTCS) based on advanced analytical and hardware redundancies for Air-Fuel Ratio (AFR) control of Spark Ignition (SI) Internal Combustion (IC) engines. The advanced analytical redundancy part is termed the Hybrid Fault-Tolerant Control System (HFTCS) which consists of both active and passive types. The Lookup Tables (LTs) have been utilized in the active part and a robust proportional feedback controller of high gain with fuel throttle actuator has been implemented in the passive part. Since the failure of any two sensors at the same time or failure of a single actuator causes engine shutdown, an advanced hardware redundancy protocol Modifi ed Triple Modular Redundancy (MTMR) has been suggested for the sensors, and Dual Redundancy (DR) has been proposed for the actuators to prevent the tripping of the engine. MATLAB/Simulink simulation results indicate that the suggested UFTCS is highly robust to the sensor faults in both normal and noisy conditions. The probabilistic reliability analysis for various hardware redundancy schemes also proves the greater overall reliability of UFTCS. Finally, a comparison with the existing AFR control systems is carried out to demonstrate its superior performance

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