Robust tracking for hypersonic vehicles subjected to mismatched uncertainties via fixed-time sliding mode control

2021 ◽  
pp. 095441002199023
Author(s):  
Jianguo Guo ◽  
Shengjiang Yang ◽  
Zongyi Guo
Keyword(s):  
Sliding Mode Control ◽  
Sliding Mode ◽  
Fixed Time ◽  
Hypersonic Vehicles ◽  
Robust Tracking ◽  
Control Approach ◽  
Mode Control ◽  
Mismatched Uncertainties ◽  
The Stability ◽  
Mismatched Disturbances

This article investigates the robust tracking issue for the longitudinal dynamics of hypersonic vehicles subjected to mismatched uncertainties, and a novel sliding mode control approach is proposed to achieve the fixed-time convergence of tracking errors and satisfactory robustness against mismatched uncertainties. Establishing the control-oriented hypersonic vehicle model as velocity and altitude subsystems with mismatched uncertainties, the article introduces the nonlinear finite-time disturbance observer technique to estimate the uncertainties precisely. With the estimated uncertainties from the observer, the fixed-time sliding mode control is presented to track the velocity and altitude references. Consequently, the effect of the mismatched disturbances can be eliminated and the tracking performance can be improved. The stability of the closed-loop system is also analyzed. Numerical simulation results demonstrate the validity and superiority of the proposed control.

New fixed-time sliding mode control for a mismatched second-order system

2020 ◽  
pp. 014233122095230
Author(s):  
Guo Jianguo ◽  
Yang Shengjiang
Keyword(s):  
Sliding Mode Control ◽  
Sliding Mode ◽  
Initial Conditions ◽  
Nonlinear Function ◽  
Fixed Time ◽  
Second Order ◽  
Order System ◽  
Time Stability ◽  
Mode Control ◽  
Mismatched Uncertainties

A fixed-time sliding mode control (FTSMC) method is proposed for a second-order system with mismatched uncertainties in this paper. A new sliding mode, which is insensitive to the mismatched disturbance, is present to eliminate the effect of mismatched uncertainties by adopting the differentiable nonlinear function, and to obtain the fixed time stability independent of initial conditions by using the fraction-order function. In order to improve the performance of control system, the extended disturbance-observer-based fixed-time sliding mode control (EDO-FTSMC) approach is investigated to obtain the fixed-time stability subject to the mismatched uncertainties. Finally, the performance of the proposed control method is illustrated to compare other control approaches with numerical simulation results and application examples.

scholarly journals Continuous Prescribed-Time Sliding Mode Control with A Prescribed-Time ESO for Second-Order Nonlinear Systems with Mismatched Disturbance

2021 ◽  
Author(s):  
Xiaozhe Ju ◽  
Feng Wang ◽  
Yingzi Guan ◽  
Shihao Xu
Keyword(s):  
Nonlinear Systems ◽  
Sliding Mode Control ◽  
Sliding Mode ◽  
Fixed Time ◽  
Second Order ◽  
Order System ◽  
Practical Applications ◽  
Mode Control ◽  
System States ◽  
Mismatched Disturbances

Abstract This paper aims to settle the continuous prescribed-time stabilization problem of second-order nonlinear systems with mismatched disturbances. A continuous prescribed-time sliding mode control (CPTSMC) method with a prescribed-time extended state observer (PTESO) is proposed. The PTESO can precisely estimate the unknown states and disturbances, with its upper bound for the settling time (UBST) prescribed by only one parameter more tightly than existing finite-time or fixed-time ESOs. Furthermore, as a common concern for ESOs, the peaking value problem is well addressed. Then, a novel prescribed-time convergent form with little conservatism and simple tuning procedures is designed, and the internal mechanism in acquiring higher transient performance is explicitly researched. By using the estimated states and disturbances, the CPTSMC makes system states converge in a chattering-alleviated manner following the novel prescribed-time form. In addition to proving that the UBST of the whole system is tightly prescribed by only one design parameter, we show the continuity of the CPTSMC and the boundedness of all system signals, which are vital for practical applications. Ultimately, numerical simulations on the second-order system and a DC motor servo verify the efficiency of the proposed control system.

Design of adaptive optimal robust control for two-flexible-link manipulators in the presence of matched uncertainties

2020 ◽  
pp. 107754632093202
Author(s):  
Hamid Reza Shafei ◽  
Mohsen Bahrami ◽  
Heidar Ali Talebi
Keyword(s):  
Sliding Mode Control ◽  
Sliding Mode ◽  
Flexible Link ◽  
External Disturbances ◽  
Terminal Sliding Mode ◽  
Control Approach ◽  
Mode Control ◽  
Nonsingular Terminal Sliding Mode ◽  
Control Scheme ◽  
The Stability

This study uses a comprehensive control approach to deal with the trajectory tracking problem of a two-flexible-link manipulator subjected to model uncertainties. Because the control inputs of two-flexible-link manipulators are less than their state variables, the proposed controller should be able to tackle the stated challenge. Practically speaking, there is only a single control signal for each joint, which can be used to suppress link deflections and control joint trajectories. To achieve this objective, a novel optimal robust control scheme, with an updated gain under the adaptive law, has been developed in this work for the first time. In this regard, a nonsingular terminal sliding mode control approach is used as the robust controller and a control Lyapunov function is used as the optimal control law, to benefit from the advantages of both methods. To systematically deal with system uncertainties, an adaptive law is used to update the gain of nonsingular terminal sliding mode control. The advantage of this approach over the existing methods is that it not only can robustly and stably control an uncertain nonlinear system against external disturbances but also can optimally solve a quadratic cost function (e.g. minimization of control effort). The Lyapunov stability theory has been applied to verify the stability of the proposed approach. Moreover, to show the superiority of this method, the computer simulation results of the proposed method have been compared with those of an adaptive sliding mode control scheme. This comparison shows that the presented approach is capable of optimizing the control inputs while achieving the stability of the examined two-flexible-link manipulator in the presence of model uncertainties and external disturbances.

scholarly journals Fixed-time sliding mode control with mismatched disturbances

Automatica ◽  
2021 ◽  
pp. 110009
Author(s):  
Emmanuel Moulay ◽  
Vincent Léchappé ◽  
Emmanuel Bernuau ◽  
Michael Defoort ◽  
Franck Plestan
Keyword(s):  
Sliding Mode Control ◽  
Sliding Mode ◽  
Fixed Time ◽  
Mode Control ◽  
Mismatched Disturbances

Linear Matrix Inequalities in Robust Unified Smooth Sliding Mode Controller Design

2012 ◽  
Author(s):  
Siew Min See ◽  
Johari Halim Shah Osman
Keyword(s):  
Sliding Mode Control ◽  
Linear Matrix Inequalities ◽  
Sliding Mode ◽  
Linear Matrix ◽  
Matrix Inequalities ◽  
H Infinity ◽  
Mode Control ◽  
Mismatched Uncertainties ◽  
Guaranteed Cost ◽  
Mismatched Disturbances

Sebahagian besar masalah yang dihadapi dalam teori kawalan sistem boleh dikurangkan kepada beberapa masalah pengoptimuman cembung atau kuasi–cembung piawai yang melibatkan ketaksamaan matriks lelurus (LMI). Dengan perkembangan terbaru tentang cara titik dalaman, masalah pengoptimuman tersebut dapat diselesaikan secara efisien dengan kaedah berangka. Satu daripada aplikasi LMI boleh dilihat dalam penyelesaian masalah kawalan ragam gelincir. Sistem kawalan ragam gelincir berkemampuan supaya tidak terpengaruh secara keseluruhan oleh ketidakpastian padanan apabila berada dalam ragam gelincir. Akan tetapi, sistem masih menghadapi gangguan yang tidak diingini apabila diusik oleh ketidakpastian tidak terpadan, serta masalah gelugutan. Dalam kertas kerja ini, permukaan gelincir direka bentuk dengan integrasi suatu kriteria H infiniti terjamin kos optimum untuk mengurangkan gangguan tidak terpadan. Permukaan kos terjamin tersebut diterbitkan daripada prosedur pengoptimuman cembung yang diformulasikan sebagai masalah LMI. Satu kawalan licin seragam diaplikasikan untuk menyelesaikan masalah gelugutan. Keputusan menunjukkan bahawa pengawal tersebut dapat memperbaiki prestasi dari segi penyingkiran gelugutan secara keseluruhan dan penyisihan gangguan tidak terpadan Kata kunci: Ketaksamaan matriks lelurus (LMI), kawalan ragam gelincir, gangguan tidak terpadan, bebas gelugutan, kriteria H infiniti terjamin kos optimum A wide range of problems encountered in system control theory can be reduced to a few standard convex or quasiconvex optimisation problems involving linear matrix inequalities (LMI). With recent developed of interior point methods, the optimisation problems can be solved numerically very efficiently. One of the applications of the LMI may be seen in solving the sliding mode control problems. The sliding mode control system is capable of total invariance to the matched uncertainties while remain in the sliding mode. But the system may still face the undesirable distractions cause by the mismatched uncertainties, and chattering problem. In this paper, the sliding surface is designed with integration of an optimal guaranteed cost H infinity criterion to attenuate the mismatched disturbances. The guaranteed cost surface is derived from a convex optimisation procedure formulated as an LMI problem. A unified smooth control law is applied to solve the chattering problem. The results showed that the controller may improve the performance with total chattering elimination and mismatched disturbances rejection. Key words: Linear matrix inequalities (LMI), sliding mode control, mismatched uncertainties, chattering free, optimal guaranteed cost H infinity criterion

scholarly journals Droop Method Development for Microgrids Control Considering Higher Order Sliding Mode Control Approach and Feeder Impedance Variation

2021 ◽  
Vol 11 (3) ◽  
pp. 967
Author(s):  
Abdonaser Saleh-Ahmadi ◽  
Mazda Moattari ◽  
Amir Gahedi ◽  
Edris Pouresmaeil
Keyword(s):  
Sliding Mode Control ◽  
Method Development ◽  
Reactive Power ◽  
Sliding Mode ◽  
Power Sharing ◽  
Control Approach ◽  
Mode Control ◽  
Impedance Variation ◽  
Parallel Mode ◽  
The Stability

Due to the growing power demands in microgrids (MGs), the necessity for parallel production achieved from distributed generations (DGs) to supply the load required by customers has been increased. Since the DGs have to procure the demand in parallel mode, they are faced with several technical and economic challenges, such as preventing DGs overloading and not losing network stability considering feeder impedance variation. This paper presents a method that upgrades the droop controller based on sliding mode approach, so that DGs are able to prepare a suitable reactive power sharing without error even in more complex MGs. In the proposed strategy, the third-order sliding mode controller significantly reduces the V-Q error and increases the accuracy in adjusting the voltage at the DG output terminals. Various case studies conducted out in this paper validate the truthfulness of the proposed method, considering the stability analysis using Lyapunov function. Finally, by comparing the control parameters of the proposed technique with existing methods, the superiority, simplicity and effectiveness of the 3rd order sliding mode control (SMC) method are determined.

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