A Novel Continuous Finite-Time Extended State Observer Design for a Class of Uncertain Nonlinear Systems

Razmjooei, Hamid; Shafiei, Mohammad Hossein; Abdi, Elahe

doi:10.1109/access.2020.3043725

Cited by 10 publications

(11 citation statements)

References 30 publications

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“…Hence, the ESO works effectively only if total disturbance does not vary significantly. Finite time observers proposed in these papers [15][16][17] rely on many design parameters and are much more difficult to design in the practical applications. With these points considered, the proposed SMESO, which is more convenient for selecting the observer gains and achieve a more concise structure, can obtain better estimation performance without requiring slow disturbance variation.…”

Section: Problem Formulationmentioning

confidence: 99%

“…Since the nonzero first time derivative of total disturbance affects the estimation performance, the conventional linear ESO usually tracks the total disturbance in infinite time. Recently, finite time control techniques [13][14][15][16][17] can provide a faster convergence rate and better system performance. In the presence of time-varying disturbances, performance of ESO estimation is a matter of concern.…”

Section: Introductionmentioning

confidence: 99%

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Applying sliding mode technique to design extended state observer for nonlinear systems

Chang

2021

Asian Journal of Control

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This paper applies sliding mode and stable pole‐zero cancelation techniques to design a finite time extended state observer for a class of single‐input single‐output nonlinear systems in the presence of unknown uncertainties and disturbances. The proposed estimation approaches, including first‐order and second‐order sliding mode extended state observers, can provide more design flexibility and achieve good performance compared with the conventional extended state observers. Moreover, it has a good form for theoretical stability analysis in which the estimation errors can be converged to a neighborhood of zero while remaining uniformly bounded in finite time. The characteristics of the developed observer is presented in the frequency domain, followed by the corresponding analysis in the time domain. Finally, simulation results demonstrate the validity of the proposed method.

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Section: Problem Formulationmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Applying sliding mode technique to design extended state observer for nonlinear systems

Chang

2021

Asian Journal of Control

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show abstract

Section: Introductionmentioning

confidence: 99%

“…Recently, time-varying observers have been well investigated [17][18][19][20][21][22][23]. For instance, some time-varying observers with exponential convergences have been presented in [17][18][19][20][21]. However, their shortcomings are as follows: (1) The estimation errors have not been considered in the control loop.…”

Section: Introductionmentioning

confidence: 99%

Non-linear Finite-Time Tracking Control of Uncertain Robotic Manipulators Using Time-Varying Disturbance Observer-Based Sliding Mode Method

Razmjooei

Shafiei

Palli

et al. 2022

J Intell Robot Syst

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In this paper, a time-varying chattering-free disturbance observer-based position tracking control law of serial robotic manipulators is presented to track a reference signal in a finite time. The key idea is to employ a positive-increasing function associated with the control/observer objectives to improve the control performance. First, the model of an uncertain robotic manipulator is presented as the case study of the proposed strategy. Then, the time-varying form of the robotic manipulator model is obtained to provide finite-time boundedness using the first-order sliding mode method. Moreover, without any knowledge about the upper bounds of the uncertainties, a reduced-order observer is presented to estimate the uncertainties in a finite time. Subsequently, a disturbance observer-based finite-time position tracking control law is designed. The time-varying gains are provided to converge the position tracking error to a neighborhood of zero in a finite time. Finally, comparative simulations are presented to show the effectiveness of the proposed scheme compared to other existing strategies.

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“…23 The finitetime ESO based on time-varying gains is designed and the non-linear system is transformed into a new timevarying form to achieve the finite-time boundedness criteria of the estimation error using the asymptotic stability methods. 24 The fractional-order sliding mode has finite-time convergence capability. Recently, a series of SMC strategies with finite-time characteristics was studied.…”

Section: Introductionmentioning

confidence: 99%

Observer-based finite-time control for trajectory tracking of lower extremity exoskeleton

Wang

Guo

2021

Proceedings of the Institution of Mechanical Engineers, Part I:

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In this article, an advanced observer-based finite-time trajectory tracking controller is investigated for lower extremity exoskeleton without available joint angular velocities to improve the movement ability of dependent persons, which is robust against uncertain dynamics, human active joint torque and external disturbances. First, the Lagrange principle is applied to analyze the dynamic properties of lower extremity exoskeleton driven by artificial pneumatic muscles, and its swing phase model is established. After that, a novel finite-time extended state observer is proposed to observe the lumped disturbances and unavailable angular velocities of the lower limb exoskeleton simultaneously. Furthermore, a finite-time sliding mode controller of exoskeleton is designed based on the extended state observer, and the finite-time convergence of tracking error is rigorously demonstrated based on the Lyapunov theory. Finally, the control system simulation is established and experimental tests are conducted with a voluntary subject during flexion of wearer’s knee and hip joints, the obtained results demonstrate fast and high-precision tracking performance of the proposed approach.

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A Novel Continuous Finite-Time Extended State Observer Design for a Class of Uncertain Nonlinear Systems

Cited by 10 publications

References 30 publications

Applying sliding mode technique to design extended state observer for nonlinear systems

Applying sliding mode technique to design extended state observer for nonlinear systems

Non-linear Finite-Time Tracking Control of Uncertain Robotic Manipulators Using Time-Varying Disturbance Observer-Based Sliding Mode Method

Observer-based finite-time control for trajectory tracking of lower extremity exoskeleton

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