scholarly journals Robust Control of Uncertain Nonlinear Systems: A Nonlinear DOBC Approach

2016 ◽  
Vol 138 (7) ◽  
Author(s):  
Wen-Hua Chen ◽  
Jun Yang ◽  
Zhenhua Zhao
Keyword(s):  
Robust Control ◽  
Nonlinear Systems ◽  
Disturbance Observer ◽  
External Disturbance ◽  
Uncertain Nonlinear Systems ◽  
Nonlinear Controller ◽  
Nonlinear Disturbance Observer ◽  
Spring System ◽  
Mass Spring ◽  
Distinct Features

This paper advocates disturbance observer-based control (DOBC) for uncertain nonlinear systems. Within this framework, a nonlinear controller is designed based on the nominal model in the absence of disturbance and uncertainty where the main design specifications are to stabilize the system and achieve good tracking performance. Then, a nonlinear disturbance observer is designed to not only estimate external disturbance but also system uncertainty/unmodeled dynamics. With described uncertainty, rigorous stability analysis of the closed-loop system under the composite controller is established in this paper. Finally, the robust control problems of a missile roll stabilization and a mass spring system are addressed to illustrative the distinct features of the nonlinear DOBC approach.

Harmonic Disturbance Observer for Nonlinear Systems

2003 ◽  
Vol 125 (1) ◽  
pp. 114-117 ◽  
Author(s):  
Wen-Hua Chen
Keyword(s):  
Nonlinear Systems ◽  
Disturbance Observer ◽  
Disturbance Attenuation ◽  
Nonlinear Controller ◽  
Gain Function ◽  
Nonlinear Gain ◽  
Nonlinear Disturbance Observer ◽  
Systematic Procedure ◽  
Nonlinear Disturbance

A nonlinear harmonic disturbance observer for nonlinear systems subject to harmonics is designed and stability of the proposed observer is established using passivity approach. A systematic procedure to choose the nonlinear gain function in the observer is proposed. The proposed nonlinear disturbance observer can be integrated with a linear/nonlinear controller to improve its disturbance attenuation ability for nonlinear systems under harmonics.

Integral terminal sliding-mode robust vibration control of large space intelligent truss structures using a disturbance observer

2021 ◽  
pp. 095441002110290
Author(s):  
Dalong Tian ◽  
Jianguo Guo
Keyword(s):  
Robust Control ◽  
Forced Vibration ◽  
Disturbance Observer ◽  
Sliding Mode ◽  
External Disturbance ◽  
Truss Structures ◽  
Model Parameters ◽  
Large Space ◽  
Terminal Sliding Mode ◽  
Piezoelectric Stack Actuator

This study aims to develop an advanced integral terminal sliding-mode robust control method using a disturbance observer (DO) to suppress the forced vibration of a large space intelligent truss structure (LSITS). First, the dynamics of the electromechanical coupling of the piezoelectric stack actuator and the LSITS, based on finite element and Lagrangian methods, are established. Subsequently, to constrict the vibration of the structure, a novel integral terminal sliding-mode control (ITSMC) law for the DO is used to estimate the parameter perturbation of the LSITS based on a continuous external disturbance. Simulation results show that, under a forced vibration and compared with the ITSMC system without a DO, the displacement amplitude of the ITSMC system with the DO is effectively reduced. In the case where the model parameters of the LSITS deviate by ±50%, and an unknown continuous external disturbance exists, the control system with the DO can adequately attenuate the structural vibration and realize robust control. Concurrently, the voltage of the employed piezoelectric stack actuator is reduced, and voltage jitter is alleviated.

scholarly journals Sliding mode control of the automobile electro-coating conveying mechanism with a nonlinear disturbance observer

2018 ◽  
Vol 10 (9) ◽  
pp. 168781401879574 ◽  
Author(s):  
Wei Yuan ◽  
Guoqin Gao
Keyword(s):  
Sliding Mode Control ◽  
Disturbance Observer ◽  
High Performance ◽  
Sliding Mode ◽  
External Disturbance ◽  
Nonlinear Disturbance Observer ◽  
Control Approach ◽  
Mode Control ◽  
Highly Nonlinear ◽  
Nonlinear Disturbance

The trajectory-tracking performance of the automobile electro-coating conveying mechanism is severely interrupted by highly nonlinear crossing couplings, unmodeled dynamics, parameter variation, friction, and unknown external disturbance. In this article, a sliding mode control with a nonlinear disturbance observer is proposed for high-accuracy motion control of the conveying mechanism. The nonlinear disturbance observer is designed to estimate not only the internal/external disturbance but also the model uncertainties. Based on the output of the nonlinear disturbance observer, a sliding mode control approach is designed for the hybrid series–parallel mechanism. Then, the stability of the closed-loop system is proved by means of a Lyapunov analysis. Finally, simulations with typical desired trajectory are presented to demonstrate the high performance of the proposed composite control scheme.

Simultaneous design of AWC and nonlinear controller for uncertain nonlinear systems under input saturation

2019 ◽  
Vol 29 (10) ◽  
pp. 2877-2897 ◽  
Author(s):  
Muntazir Hussain ◽  
Muhammad Rehan ◽  
Choon Ki Ahn ◽  
Keum‐Shik Hong ◽  
Najam us Saqib
Keyword(s):  
Nonlinear Systems ◽  
Input Saturation ◽  
Uncertain Nonlinear Systems ◽  
Nonlinear Controller ◽  
Simultaneous Design

scholarly journals Nonsingular Fast Terminal Sliding Mode Tracking Control for a Class of Uncertain Nonlinear Systems

2019 ◽  
Vol 2019 ◽  
pp. 1-17
Author(s):  
Siyi Chen ◽  
Wei Liu ◽  
Huixian Huang
Keyword(s):  
Nonlinear Systems ◽  
Sliding Mode Control ◽  
Tracking Control ◽  
Disturbance Observer ◽  
Sliding Mode ◽  
Terminal Sliding Mode Control ◽  
Uncertain Nonlinear Systems ◽  
Terminal Sliding Mode ◽  
Rbf Network ◽  
Fast Terminal Sliding Mode

Aiming at the tracking control problem of a class of uncertain nonlinear systems, a nonsingular fast terminal sliding mode control scheme combining RBF network and disturbance observer is proposed. The sliding mode controller is designed by using nonsingular fast terminal sliding mode and second power reaching law to solve the problem of singularity and slow convergence in traditional terminal sliding mode control. By using the universal approximation of RBF network, the unknown nonlinear function of the system is approximated, and the disturbance observer is designed by using the hyperbolic tangent nonlinear tracking differentiator (TANH-NTD) to estimate the interference of the system and enhance the robustness of the system. The stability of the system is proved by the Lyapunov principle. The numerical simulation results show that the method can shorten the system arrival time, improve the tracking accuracy, and suppress the chattering phenomenon.

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