Robust Nonsingular Terminal Sliding-Mode Control for Nonlinear Magnetic Bearing System
ABSTRACT This study presents a robust nonsingular terminal sliding-mode control (RNTSMC) system to achieve finite time tracking control (FTTC) for the rotor position in the axial direction of a nonlinear thrust active magnetic bearing (TAMB) system. Compared with conventional sliding-mode control (SMC) with linear sliding surface, terminal sliding-mode control (TSMC) with nonlinear terminal sliding surface provides faster, finite time convergence, and higher control precision. In this study, first, the operating principles and dynamic model of the TAMB system using a linearized electromagnetic force model are introduced. Then, the TSMC system is designed for the TAMB to achieve FTTC. Moreover, in order to overcome the singularity problem of the TSMC, a nonsingular terminal sliding-mode control (NTSMC) system is proposed. Furthermore, since the control characteristics of the TAMB are highly nonlinear and time-varying, the RNTSMC system with a recurrent Hermite neural network (RHNN) uncertainty estimator is proposed to improve the control performance and increase the robustness of the TAMB control system. Using the proposed RNTSMC system, the bound of the lumped uncertainty of the TAMB is not required to be known in advance. Finally, some experimental results for the tracking of various reference trajectories demonstrate the validity of the proposed RNTSMC for practical TAMB applications.
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ABSTRACT: A partial integrated guidance and control design for an interception with terminal impact angle constraints in three-dimensional space is presented in this paper. A three-dimensional nonlinear engagement dynamic is considered here and full nonlinear six-degrees-of-freedom model of the interceptor with aerodynamic uncertainties has been accounted for. The partial integrated guidance and control design contains a two-loop controller structure. The outer loop, which generates directly the commanded body rates, is constructed, and then the inner loop is designed to track the outer loop commands. The main feature of the partial integrated guidance and control design is that it accurately satisfies terminal impact angle constraints in both azimuth and elevation, in addition to being capable of hitting the target with high accuracy. Moreover, the aerodynamic uncertainties and the target acceleration, which are assumed to be bounded, are considered by virtue of the proposed adaptive multiple input multiple output sliding mode control method. The performance of the proposed scheme is investigated using nonlinear simulation studies. A comparison among the proposed partial integrated guidance and control method, the conventional method where the guidance and control loops are designed separately, and the integrated guidance and control method executed in a single loop is presented to show the effectiveness of the proposed partial integrated guidance and control scheme. Finally, a Monte Carlo study is conducted to test the robustness to aerodynamic uncertainties.Journal of Guidance Control and Dynamics 03/2014; 37(2):644-657. DOI:10.2514/1.60133 · 1.15 Impact Factor
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ABSTRACT: This paper proposes a sensorless control technique solving the tracking problem of the Maximum Delivered Power characteristic for a Permanent Magnet Synchronous Generator equipped Wind Energy Conversion System. A previously published control scheme ensuring the achievement of maximum power efficiency of the wind turbine, not requiring feedback information about rotor speed and position, and about wind velocity, is here extended to consider the drive-train dynamics. Moreover, it is proved that the derived control algorithm can be easily modified to ensure also fault accommodation with respect to a class of system faults, sensor faults being absent because of the sensorless approach here pursued.2014 European Control Conference (ECC); 06/2014
Journal of Guidance Control and Dynamics 02/2015; DOI:10.2514/1.G000912 · 1.15 Impact Factor