A Novel Nonlinear Disturbance Observer embedded Second-Order Finite Time Tracking-based Controller for Robotic Manipulators

2021 ◽  
pp. 1-27
Author(s):  
Bin Ren ◽  
Yao Wang ◽  
Jiayu Chen ◽  
Silu Chen
Keyword(s):  
Finite Time ◽  
Disturbance Observer ◽  
Sliding Mode ◽  
Tracking Error ◽  
Robotic Manipulators ◽  
Second Order ◽  
Terminal Sliding Mode ◽  
Nonlinear Disturbance Observer ◽  
Nonlinear Disturbance ◽  
Nonlinear Mechanical Systems

Abstract Robotic manipulators are complex and dynamic nonlinear mechanical systems subject to numerous uncertainties, such as payload variations, frictions, and unmodeled dynamics. To mitigate the uncertainty caused by these disturbances and minimize the tracking errors of the controllers, this study proposed a finite time tracking-based controller (FTC) that embeds a nonlinear disturbance observer (NDO) and a second-order sliding mode modifier (SOSM). The NDO was incorporated to compensate for the system's global bounded uncertainty and the SOSM employed a robust nonsingular terminal sliding-mode modifier to stabilize the controller. The theoretical analysis showed that the tracking error could quickly converge in finite time. Simulation on a typical robotics manipulator demonstrated the practical appeal of the proposed scheme.

Research on Terminal Piecewise Sliding Mode for Excitation Control System Based on the Nonlinear Disturbance Observer

2014 ◽  
Vol 711 ◽  
pp. 297-302
Author(s):  
Xiao Feng Liu ◽  
Hong Zhang ◽  
He Qiao
Keyword(s):  
Disturbance Observer ◽  
Convergence Rates ◽  
Sliding Mode ◽  
Terminal Sliding Mode ◽  
Nonlinear Disturbance Observer ◽  
Disturbance Estimation ◽  
Guarantee System ◽  
Control Precision ◽  
Nonlinear Disturbance ◽  
High Control

Aiming at uncertainty and disturbance of the excitation system, we designed a kind of precise sliding mode controller with nonlinear disturbance observer that realized disturbance estimation and compensation. In order to obtain better convergence rates, based on the basis of fast terminal sliding mode surface, terminal piecewise sliding mode is adopted. Using the single machine infinite system, we have carried on the static and transient simulation. Simulation results show that control strategy adopted can guarantee system robustness to disturbance and has high control precision

Smooth second-order nonsingular terminal sliding mode control for reusable launch vehicles

2014 ◽  
Vol 7 (1) ◽  
pp. 95-110 ◽  
Author(s):  
Shaobo Ni ◽  
Jiayuan Shan
Keyword(s):  
Finite Time ◽  
Sliding Mode ◽  
Tracking Error ◽  
Second Order ◽  
Convergence Time ◽  
Control Input ◽  
Terminal Sliding Mode ◽  
Content Type ◽  
Nonsingular Terminal Sliding Mode ◽  
Attitude Tracking

Purpose – The purpose of this paper is to present a sliding mode attitude controller for reusable launch vehicle (RLV) which is nonlinear, coupling, and includes uncertain parameters and external disturbances. Design/methodology/approach – A smooth second-order nonsingular terminal sliding mode (NTSM) controller is proposed for RLV in reentry phase. First, a NTSM manifold is proposed for finite-time convergence. Then a smooth second sliding mode controller is designed to establish the sliding mode. An observer is utilized to estimate the lumped disturbance and the estimation result is used for feedforward compensation in the controller. Findings – It is mathematically proved that the proposed sliding mode technique makes the attitude tracking errors converge to zero in finite time and the convergence time is estimated. Simulations are made for RLV through the assumption that aerodynamic parameters and atmospheric density are perturbed. Simulation results demonstrate that the proposed control strategy is effective, leading to promising performance and robustness. Originality/value – By the proposed controller, the second-order sliding mode is established. The attitude tracking error converges to zero in a finite time. Meanwhile, the chattering is alleviated and a smooth control input is obtained.

scholarly journals Terminal Sliding Mode Control of Mobile Wheeled Inverted Pendulum System with Nonlinear Disturbance Observer

2014 ◽  
Vol 2014 ◽  
pp. 1-8 ◽  
Author(s):  
SongHyok Ri ◽  
Jian Huang ◽  
Yongji Wang ◽  
MyongHo Kim ◽  
Sonchol An
Keyword(s):  
Disturbance Observer ◽  
Inverted Pendulum ◽  
Sliding Mode ◽  
Sliding Mode Controller ◽  
Terminal Sliding Mode ◽  
Pendulum System ◽  
Nonlinear Disturbance Observer ◽  
Inverted Pendulum System ◽  
Wheeled Inverted Pendulum ◽  
Nonlinear Disturbance

A terminal sliding mode controller with nonlinear disturbance observer is investigated to control mobile wheeled inverted pendulum system. In order to eliminate the main drawback of the sliding mode control, “chattering” phenomenon, and for compensation of the model uncertainties and external disturbance, we designed a nonlinear disturbance observer of the mobile wheeled inverted pendulum system. Based on the nonlinear disturbance observer, a terminal sliding mode controller is also proposed. The stability of the closed-loop mobile wheeled inverted pendulum system is proved by Lyapunov theorem. Simulation results show that the terminal sliding mode controller with nonlinear disturbance observer can eliminate the “chattering” phenomenon, improve the control precision, and suppress the effects of external disturbance and model uncertainties effectively.

Disturbance observer based dynamic surface flight control for an uncertain aircraft

2017 ◽  
Vol 232 (4) ◽  
pp. 729-744 ◽  
Author(s):  
Jianjun Ma ◽  
Peng Li ◽  
Zhiqiang Zheng
Keyword(s):  
Flight Control ◽  
Disturbance Observer ◽  
Sliding Mode ◽  
Tracking Error ◽  
Small Neighborhood ◽  
Dynamic Surface ◽  
Nonlinear Disturbance Observer ◽  
Actuator Dynamics ◽  
Highly Nonlinear ◽  
Nonlinear Disturbance

To handle the flight control problem of an uncertain aircraft with highly nonlinear characteristics, internal uncertainties and external disturbances, an adaptive dynamic surface controller based on nonlinear disturbance observer is designed in this paper. A novel nonhomogeneous nonlinear disturbance observer is designed to approximate the uncertainties and disturbances, which can exactly estimate the disturbances in finite time. Dynamic surface control is utilized to avoid the explosion of complexity in traditional backstepping design. Through Lyapunov synthesis, the closed-loop control system is demonstrated to be semi-globally uniformly ultimately bounded and the tracking error converges to a small neighborhood of origin. Besides, actuator dynamics are taken into account, and the controller for actuator dynamics with consideration of limitation is developed based on sliding-mode control theory. The effectiveness of the proposed control is shown by simulation experiments.

scholarly journals An Active Fault-Tolerant Control for Robotic Manipulators Using Adaptive Non-Singular Fast Terminal Sliding Mode Control and Disturbance Observer

Actuators ◽  
2021 ◽  
Vol 10 (12) ◽  
pp. 332
Author(s):  
Van-Cuong Nguyen ◽  
Phu-Nguyen Le ◽  
Hee-Jun Kang
Keyword(s):  
Sliding Mode Control ◽  
Finite Time ◽  
Disturbance Observer ◽  
Fault Tolerant ◽  
Sliding Mode ◽  
Robotic Manipulators ◽  
Terminal Sliding Mode Control ◽  
Terminal Sliding Mode ◽  
Finite Time Convergence ◽  
Fast Terminal Sliding Mode

In this study, a fault-tolerant control (FTC) tactic using a sliding mode controller–observer method for uncertain and faulty robotic manipulators is proposed. First, a finite-time disturbance observer (DO) is proposed based on the sliding mode observer to approximate the lumped uncertainties and faults (LUaF). The observer offers high precision, quick convergence, low chattering, and finite-time convergence estimating information. Then, the estimated signal is employed to construct an adaptive non-singular fast terminal sliding mode control law, in which an adaptive law is employed to approximate the switching gain. This estimation helps the controller automatically adapt to the LUaF. Consequently, the combination of the proposed controller–observer approach delivers better qualities such as increased position tracking accuracy, reducing chattering effect, providing finite-time convergence, and robustness against the effect of the LUaF. The Lyapunov theory is employed to illustrate the robotic system’s stability and finite-time convergence. Finally, simulations using a 2-DOF serial robotic manipulator verify the efficacy of the proposed method.

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