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.
Conference Paper: Terminal sliding mode control of mobile wheeled inverted pendulum[Show abstract] [Hide abstract]
ABSTRACT: The mobile wheeled inverted pendulum is widely used in many robotic applications and also paid attention by theorists due to its essentially unstable. The equilibrium control and velocity control of a mobile wheeled inverted pendulum are discussed in this paper. Based on the three-dimensional (3D) dynamic model of this underactuated system running on the flat ground derived by Lagrange's motion equation, a terminal sliding mode control (TSMC) is proposed to ensure the underactuated system can be self-balanced and variables converge to desired states. By using the proposed controller, the system can stay at the equilibrium or track a given yaw angle. Numerical simulations are provided to verify and illustrate the effectiveness of the proposed model and controllers.Modelling, Identification & Control (ICMIC), 2012 Proceedings of International Conference on; 01/2012
Conference Paper: Exact-estimator-based terminal sliding mode control system design[Show abstract] [Hide abstract]
ABSTRACT: This paper investigates an estimator-based terminal sliding mode control system. An exact estimator is proposed to exactly estimate the unknown uncertainties in finite time. The output of the exact estimator is used to design a continuous chattering free terminal sliding mode control. The time taken for the closed-loop system to reach zero tracking error is proven to be finite. Experiment results are presented, using a real time digital-signal-processor (DSP) based electromagnetic-levitation system to implement the control performance.Control Conference (ASCC), 2013 9th Asian; 01/2013
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ABSTRACT: In this paper, a fractional calculus-based terminal sliding mode controller is introduced for finite-time control of non-autonomous non-linear dynamical systems in the canonical form. A fractional terminal switching manifold which is appropriate for canonical integer-order systems is firstly designed. Then some conditions are provided to avoid the inherent singularities of the conventional terminal sliding manifolds. A non-smooth Lyapunov function is adopted to prove the finite time stability and convergence of the sliding mode dynamics. Afterward, based on the sliding mode control theory, an equivalent control and a discontinuous control law are designed to guarantee the occurrence of the sliding motion in finite time. The proposed control scheme uses only one control input to stabilize the system. The proposed controller is also robust against system uncertainties and external disturbances. Two illustrative examples show the effectiveness and applicability of the proposed fractional finite-time control strategy. It is worth noting that the proposed sliding mode controller can be applied for control and stabilization of a large class of non-autonomous non-linear uncertain canonical systems.Nonlinear Dynamics 01/2014; 75(3). · 3.01 Impact Factor