Fixed-time Disturbance Observer-based Sliding Mode Control for Mismatched Uncertain Systems

Wang, Yang; Chen, Mingshu

doi:10.1007/s12555-021-0097-x

Cited by 9 publications

(5 citation statements)

References 39 publications

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“…[1] addresses this situation by providing a rigorous finite‐time stability analysis that proves the system variables and states will not escape to infinity during the convergence process of the estimation. Similar results have been reported in [16, 23–26]. Furthermore, [27] not only proves the upper bound of system states during the estimation process but also proposes a new approach for designing a switched hybrid control strategy based on a fixed‐time DOB.…”

Section: Introductionsupporting

confidence: 83%

“…It is worth noting that the conventional linear SMC cannot handle mismatched terms. To address this issue, various improvements have been proposed, such as LMI-based SMC [14] and adaptive SMC [15], while the above-mentioned modified SMC schemes require that the mismatched disturbances satisfy the H 2 norm-bounded assumption, which is unreasonable since the mismatched disturbances always belong to nonvanishing uncertainties [16]. In recent years, DOB-based SMC strategies have been proposed to suppress mismatched disturbances, relax the unreasonable H 2 norm-bounded assumption, and maintain the nominal robust performance of SMC.…”

Section: Introductionmentioning

confidence: 99%

“…As such, the proposed scheme overcomes the limitation of varying convergence times across distinct control entities. 2.In comparison to the works presented in [16, 17, 21, 26], and taking inspiration from [13], this paper proposes a robust sliding mode variable that can effectively suppress the mismatched disturbance. To enhance the control performance, the proposed controller employs two DOBs, which relax the sliding mode coefficient selection and improve the robustness of the system.…”

Section: Introductionmentioning

confidence: 99%

See 2 more Smart Citations

A novel composite fixed‐time sliding mode control scheme for second‐order systems with mismatched disturbances: application to Buck converter

Cai,

Sun,

Zeng

2023

IET Control Theory & Appl

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In this paper, a composite fixed‐time sliding mode controller is proposed to address the problems of finite‐time escape and large initial error inherent in disturbance observer (DOB) based controllers. The proposed hybrid control strategy utilizes a fixed‐time DOB and is designed to stabilize a class of second‐order systems in the presence of both matched and mismatched disturbances, while ensuring fixed‐time convergence. First, a fixed‐time DOB is developed to estimate both types of disturbances. Second, a robust sliding mode variable with variable exponent coefficient and a former finite‐time sliding mode controller are proposed to guarantee state convergence without using DOB estimation, thereby preventing the state from diverging due to the unknown large initial error caused by DOB and ensuring convergence prior to switching. Third, a latter robust fixed‐time DOB‐based controller is designed after exact estimation of disturbances is achieved and an estimation of the overall convergence time is provided. Furthermore, strict Lyapunov analysis is employed to prove that the disturbed system under the fixed‐time DOB and composite sliding mode controller is fixed‐time stable. Simulation results for a standard planar uncertain system and Buck converter with mismatched disturbance demonstrate the effectiveness of the proposed controller.

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Section: Introductionsupporting

confidence: 83%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

See 1 more Smart Citation

A novel composite fixed‐time sliding mode control scheme for second‐order systems with mismatched disturbances: application to Buck converter

Cai,

Sun,

Zeng

2023

IET Control Theory & Appl

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“…There are six-degrees of freedom (out of which three describe translational motion and three describe rotational motion) while the drone's dynamic model receives only four control inputs (a lift force and three torques which define the turn angles of the quadropter) [42][43]. The complete 6-DOF dynamic model of the quadrotor is a highly nonlinear one and its control is usually performed with (i) global linearization control methods [44][45], (ii) local linearization control methods [46][47][48] and (iii) Lyapunov analysis-based methods [49][50][51]. The present article demonstrates solution of the nonlinear control problem of 6-DOF unmanned quadrotors with the use of flatness-based control implemented in successive loops.…”

Section: Introductionmentioning

confidence: 99%

Flatness-Based Control in Successive Loops for Autonomous Quadrotors

Rigatos,

Abbaszadeh,

Busawon

et al. 2023

Journal of Dynamic Systems, Measurement, and Control

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The control problem for the multivariable and nonlinear dynamics of unmanned rotorcrafts is treated with the use of a flatness-based control approach which is implemented in successive loops. The state-space model of 6-DOF autonomous quadrotors is separated into two subsystems, which are connected between them in cascading loops. Each one of these subsystems can be viewed independently as a differentially flat system and control about it can be performed with inversion of its dynamics as in the case of input-output linearized flat systems. The state variables of the second subsystem become virtual control inputs for the first subsystem. In turn, exogenous control inputs are applied to the second subsystem. The whole control method is implemented in two successive loops and its global stability properties are also proven through Lyapunov stability analysis. The validity of the control method is further confirmed through simulation experiments showing precise tracking of 3D flight paths by the 6-DOF quadrotor.

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“…Recently, a series of SMC with finite-time/fixed-time convergence have been introduced along with the expansion of FnTCM and FxTCM theory, such as Integral SMC (ISMC) [ 26 , 27 ], Terminal SMC (TSMC) [ 28 , 29 ], Non-singular TSMC (NTSMC) [ 30 , 31 ], Fast TSMC (FTSMC) [ 29 , 32 , 33 ], Fast NTSMC (FNTSMC) [ 34 , 35 ], and so on. Therefore, the Finite-Time Disturbance Observers (FnTDOs) or Fixed-Time Disturbance Observers (FxTDOs) have been developed such as Second-Order Sliding Mode Observer (SOSMO) [ 16 , 36 ], Uniform SOSMO (USOSMO) [ 37 , 38 ], or Third-Order Sliding Mode Observer (TOSMO) [ 14 , 39 , 40 ]. It can be seen from a comparison between FnTDO and FxTDO that under the same observer’s gains, FnTDO cannot achieve a similar fast convergence performance as FxTDO.…”

Section: Introductionmentioning

confidence: 99%

An Adaptive Prescribed Performance Tracking Motion Control Methodology for Robotic Manipulators with Global Finite-Time Stability

Truong

Kang

2022

Sensors

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In this paper, the problem of an APPTMC for manipulators is investigated. During the robot’s operation, the error states should be kept within an outlined range to ensure a steady-state and dynamic attitude. Firstly, we propose the modified PPFs. Afterward, a series of transformed errors is used to convert “constrained” systems into equivalent “unconstrained” ones, to facilitate control design. The modified PPFs ensure position tracking errors are managed in a pre-designed performance domain. Especially, the SSE boundaries will be symmetrical to zero, so when the transformed error is zero, the tracking error will be as well. Secondly, a modified NISMS based on the transformed errors allows for determining the highest acceptable range of the tracking errors in the steady-state, finite-time convergence index, and singularity elimination. Thirdly, a fixed-time USOSMO is proposed to directly estimate the lumped uncertainty. Fourthly, an ASTwCL is applied to deal with observer output errors and chattering. Finally, an observer-based-control solution is synthesized from the above techniques to achieve PCP in the sense of finite-time Lyapunov stability. In addition, the precision, robustness, as well as harmful chattering reduction of the proposed APPTMC are improved significantly. The Lyapunov theory is used to analyze the stability of closed-loop systems. Throughout simulations, the proposed PPTMC has been shown to perform well and be effective.

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Fixed-time Disturbance Observer-based Sliding Mode Control for Mismatched Uncertain Systems

Cited by 9 publications

References 39 publications

A novel composite fixed‐time sliding mode control scheme for second‐order systems with mismatched disturbances: application to Buck converter

A novel composite fixed‐time sliding mode control scheme for second‐order systems with mismatched disturbances: application to Buck converter

Flatness-Based Control in Successive Loops for Autonomous Quadrotors

An Adaptive Prescribed Performance Tracking Motion Control Methodology for Robotic Manipulators with Global Finite-Time Stability

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