This paper presents a robust observer-based finite-time convergent guidance law to intercept maneuvering targets. To avoid the undesired chattering phenomenon existing in classical sliding mode control, the adaptive s...
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This paper presents a robust observer-based finite-time convergent guidance law to intercept maneuvering targets. To avoid the undesired chattering phenomenon existing in classical sliding mode control, the adaptive super-twisting algorithm is first introduced to design a robust guidance law to drive the line-of-sight (LOS) angular rates to a small region around the origin in finite time. The important feature of the proposed adaptation algorithm is in nonoverestimating the values of the guidance law gains, which is achieved by using a detector' scheme in the updating law. Moreover, with the proposed adaptive law, the presented guidance law requires no information on target maneuvers. Since the LOS angular rate is difficult for a pursuer to measure accurately for some seekers, a novel adaptivesuper-twisting observer is proposed to estimate it and a composite guidance law is then synthesized. Detailed finite-time stability analysis and comparison results with other guidance laws demonstrate the superiority of the proposed formulation.
This paper develops a novel global nonsingular terminal sliding mode control (GNTSMC) strategy based on an adaptive super-twisting algorithm (STA) for tracking control of robotic manipulators with uncertain perturbati...
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This paper develops a novel global nonsingular terminal sliding mode control (GNTSMC) strategy based on an adaptive super-twisting algorithm (STA) for tracking control of robotic manipulators with uncertain perturbations. A novel global nonsingular terminal sliding manifold is designed to steer the system trajectory to reach the switching surface at the beginning, thereby removing the reaching stage and achieving strong robustness throughout the entire response. Moreover, the proposed sliding manifold can ensure the finite time convergence of the trajectory error to the origin. Then, an adaptive STA, which does not require the boundary information of the perturbations, is devised not only to attenuate the chattering effect without degrading the tracking precision, but also to guarantee the finite time stability of the system. Finally, the superiority of the adopted GNTSMC is validated by comparative studies.
This article addresses the attitude manoeuvre control without unwinding based on variable gain (i.e. adaptive) super-twistingalgorithm (STA) and the modified Rodrigues parameters (MRPs). First, a selection logic for ...
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This article addresses the attitude manoeuvre control without unwinding based on variable gain (i.e. adaptive) super-twistingalgorithm (STA) and the modified Rodrigues parameters (MRPs). First, a selection logic for the MRP set and its shadow set is designed in order to construct an attitude control system model for rigid spacecraft. Second, a nonlinear sliding function is presented, and on the sliding phase, finite-time convergence and anti-unwinding performance are guaranteed. As a result, a first-order sliding mode controller is created to ensure finite-time convergence and anti-unwinding performance on the reaching phase. To alleviate the chattering and improve convergence speed, an adaptive STA is presented, and the finite-time convergence and anti-unwinding performance are guaranteed on the reaching phase. Furthermore, the adaptive gains are designed based on dual-layer adaptive law, which allows the gains to be increased and decreased as appropriate. It is further demonstrated that when the controller gains are time-varying according to adaptive law, the convergence property and anti-unwinding performance are guaranteed. Numerical simulations are carried out to illustrate the closed-loop system's performance under the proposed control scheme.
This paper proposes an extended-state-observer-based distributed robust secondary voltage and frequency control for an autonomous microgrid (MG) with inverter-based distributed generators (DGs) considering the uncerta...
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This paper proposes an extended-state-observer-based distributed robust secondary voltage and frequency control for an autonomous microgrid (MG) with inverter-based distributed generators (DGs) considering the uncertainties from models and measurement noise. The MG is considered as a multi-agent system where each DG is defined as an agent and its controller only requires its own information and the information of its neighbors, but each DG obtains noisy measurements of the states of itself and its neighbors easily due to stochastic noise. Therefore, in this paper, an extended state observer is employed to estimate the accurate state information of each DG, which is significantly influenced by measurement noise. Furthermore, the distributed controllers based on a fast terminal sliding mode surface and an adaptive super-twisting algorithm are designed to track the voltage reference and to fasten the convergence rate against disturbances and uncertainties caused by parameter perturbation. Moreover, the distributed frequency controllers are also designed to restore the frequency and to guarantee the accurate active power sharing without power information of DGs. Finally, the effectiveness of the propose control strategy is illustrated by the simulation of an autonomous MG in MATLABSimulink.
This paper investigates roll suppression of marine vessels subjected to harmonic wave excitations. Bifurcation analysis is utilized to describe the stability range in detail where dynamical behaviors including chaos a...
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This paper investigates roll suppression of marine vessels subjected to harmonic wave excitations. Bifurcation analysis is utilized to describe the stability range in detail where dynamical behaviors including chaos are observed under variations of control parameters. adaptive sliding mode control with super-twistingalgorithm has been introduced to reduce chattering phenomenon of control activity as well as to guarantee roll control accuracy. The stability of the complete controlled system with adaptive mechanism has been proven by Lyapunov stability theory. The key contribution of this work is to show the significant mitigation of chattering with non-overestimating gains using a novel sliding model control structure. Extensive simulation results have been provided to verify the effectiveness of the proposed robust controller against exogenous disturbances. Finally, the adaptivesuper-twisting controller provides rapid convergence on sliding mode variables on roll motions with high accuracy, and the chattering has been considerably reduced or almost eliminated to be desired.
A novel kind of adaptive second order sliding mode control algorithm, based on super-twisting control law (STW), is proposed and applied to a floating wind turbine (FWT). This new algorithm, for which the controller g...
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A novel kind of adaptive second order sliding mode control algorithm, based on super-twisting control law (STW), is proposed and applied to a floating wind turbine (FWT). This new algorithm, for which the controller gains are dynamically adjusted with respect to the uncertainties and perturbations, has a very reduced number of tuning parameters versus previous adaptive versions of STW, and low-requirement computational requirement. This new controller is particularly well-adapted to the FWT control problems because the achievement of an accurate modeling of such system is a hard task;furthermore, it strongly reduces the tuning effort with respect to previous adaptive versions of STW. The proposed algorithm is implemented on a FAST nonlinear FWT model in the SIMULINK environment, and the performances are compared with the standard gain scheduling PI (GSPI) control and the original adaptive STW. The results show high performances of the proposed controller for rotor speed regulation and reduction of platform pitch motion.
Tidal Stream Turbine (TST) becomes more and more important due to the serious environmental and energy issues. Doubly Salient Permanent Magnet Generator (DSPMG), a fascinating machine with durable design, large torque...
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Tidal Stream Turbine (TST) becomes more and more important due to the serious environmental and energy issues. Doubly Salient Permanent Magnet Generator (DSPMG), a fascinating machine with durable design, large torque, and high-power density, has a great prospect in TST. Nevertheless, the flux linkage and inductance of this machine have the same periodical variation due to the stator-Permanent Magnet (PM) structure. It not only causes the inherent torque ripple with the conventional sinusoidal current waveform but also makes the system nonlinear and strongly coupled even after the coordinate transformation. Thus, in order to control the complex systems stably and accurately, High-Order Sliding Mode Control (HOSMC) strategy based on adaptivesupertwistingalgorithm (ASTA) is proposed for DSPMG-based TST in this paper. Firstly, First-Order Sliding Mode Control (FOSMC) and super-twistingalgorithm (STA)-based HOSMC are designed respectively for the current loop in d-q coordinate system. Then, considering the difficulties of the parameters tuning timely in variable conditions, adaptive control is applied to STA-based HOSMC. The stability of this system in a finite time is proved subsequently. Eventually, according to the simulation results, ASTA-based HOSMC has the least torque ripple, highest control accuracy, and strongest robustness compared with the other controllers.
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