scholarly journals Speed Control of Permanent Magnet DC Motor with Friction and Measurement Noise Using Novel Nonlinear Extended State Observer-Based Anti-Disturbance Control

Energies ◽  
2019 ◽  
Vol 12 (9) ◽  
pp. 1651 ◽  
Author(s):  
Amjad J. Humaidi ◽  
Ibraheem Kasim Ibraheem
Keyword(s):  
Permanent Magnet ◽  
Finite Time ◽  
Nonlinear Function ◽  
State Observer ◽  
Lyapunov Theory ◽  
Extended State Observer ◽  
Extended State ◽  
Disturbance Rejection Control ◽  
Single Term ◽  
Nonlinear Extended State Observer

In this paper, a novel finite-time nonlinear extended state observer (NLESO) is proposed and employed in active disturbance rejection control (ADRC) to stabilize a nonlinear system against system’s uncertainties and discontinuous disturbances using output feedback based control. The first task was to aggregate the uncertainties, disturbances, and any other undesired nonlinearities in the system into a single term called the “generalized disturbance”. Consequently, the NLESO estimates the generalized disturbance and cancel it from the input channel in an online fashion. A peaking phenomenon that existed in linear ESO (LESO) has been reduced significantly by adopting a saturation-like nonlinear function in the proposed nonlinear ESO (NLESO). Stability analysis of the NLEO is studied using finite-time Lyapunov theory, and the comparisons are presented over simulations on permanent magnet DC (PMDC) motor to confirm the effectiveness of the proposed observer concerning LESO.

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

2021 ◽  
pp. 095965182110337
Author(s):  
Jie Wang ◽  
Jiahao Liu ◽  
Lingling Chen ◽  
Shijie Guo
Keyword(s):  
Lower Extremity ◽  
Trajectory Tracking ◽  
Finite Time ◽  
State Observer ◽  
Lyapunov Theory ◽  
Extended State Observer ◽  
Joint Torque ◽  
Extended State ◽  
Uncertain Dynamics ◽  
Angular Velocities

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.

scholarly journals An Adaptive Nonlinear Extended State Observer for the Sensorless Speed Control of a PMSM

2015 ◽  
Vol 2015 ◽  
pp. 1-14 ◽  
Author(s):  
Minggang Gan ◽  
Chenyi Wang
Keyword(s):  
Electromotive Force ◽  
Estimation Error ◽  
Permanent Magnet Synchronous Motor ◽  
Speed Control ◽  
State Observer ◽  
Lyapunov Theory ◽  
Extended State Observer ◽  
Rotor Speed ◽  
Extended State ◽  
Nonlinear Extended State Observer

This paper presents a sensorless speed control strategy for a permanent-magnet synchronous motor (PMSM) based on an adaptive nonlinear extended state observer (ANLESO). In this paper, an extended state observer (ESO), which takes back-EMF (back electromotive force) as an extended state, is used to estimate the rotor position and the rotor speed because of its simpler structure and higher accuracy. Both linear ESO (LESO) and nonlinear ESO (NLESO) are considered to estimate the back-EMF of PMSM, and NLESO is finally implemented due to its obvious advantage in convergence. The convergence characteristics of the estimation error of the observer are analyzed by the Lyapunov theory. In order to take both stability and steady-state error into consideration, an adaptive NLESO is proposed, which adaptively adjusts the parameters of NLESO to a compromised value. The performance of the proposed method was demonstrated by simulations and experiments.

scholarly journals Disturbance and Uncertainty Suppression Control for a Saucer-Shaped Unmanned Aerial Vehicle Based on Extended State Observer

2020 ◽  
Vol 10 (14) ◽  
pp. 4884
Author(s):  
Jia Deng ◽  
Cong Feng ◽  
Hongbo Zhao ◽  
Yongming Wen ◽  
Sentang Wu
Keyword(s):  
Flight Control ◽  
Finite Time ◽  
Coupling Effect ◽  
External Disturbance ◽  
Time Estimation ◽  
State Observer ◽  
Lyapunov Theory ◽  
Extended State Observer ◽  
Extended State ◽  
Model Approximation

For saucer-shaped unmanned aerial vehicles with blended wing bodies (BWBs), un-modelled coupling effect uncertainty and external disturbance missing the matching conditions have always been the concerns. To solve this flight control problem, this research has proposed a composite backstepping controller incorporated with a finite-time convergent differentiator and a nonlinear extended state observer (ESO). More specifically, the differentiator is employed to obtain the derivatives of the virtual control laws in finite-time and therefore eliminate the inherent “explosion of term” problem in backstepping. By the effective real-time estimation of ESO without the peaking value problem, the total effect of internal uncertainties and external disturbances is compensated in the control law design, which can dispense with parameter identification and model approximation. Furthermore, based on Lyapunov theory, it is proved rigorously that all the signals of the resulting closed-loop systems are bounded. In the final part of this paper, simulation results are presented to validate the effectiveness of the proposed control scheme.

Extended state observer–based output feedback control for spacecraft pose tracking with control input saturation

2021 ◽  
pp. 095441002110177
Author(s):  
Kejie Gong ◽  
Ying Liao ◽  
Yafei Mei
Keyword(s):  
Feedback Control ◽  
Output Feedback ◽  
Finite Time ◽  
Output Feedback Control ◽  
State Observer ◽  
Extended State Observer ◽  
Control Input ◽  
Extended State ◽  
Pose Tracking ◽  
Control Scheme

This article proposed an extended state observer (ESO)–based output feedback control scheme for rigid spacecraft pose tracking without velocity feedback, which accounts for inertial uncertainties, external disturbances, and control input constraints. In this research, the 6-DOF tracking error dynamics is described by the exponential coordinates on SE(3). A novel continuous finite-time ESO is proposed to estimate the velocity information and the compound disturbance, and the estimations are utilized in the control law design. The ESO ensures a finite-time uniform ultimately bounded stability of the observation states, which is proved utilizing the homogeneity method. A non-singular finite-time terminal sliding mode controller based on super-twisting technology is proposed, which would drive spacecraft tracking the desired states. The other two observer-based controllers are also proposed for comparison. The superiorities of the proposed control scheme are demonstrated by theory analyses and numerical simulations.

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