scholarly journals Nonlinear Backstepping Control Design for Coupled Nonlinear Systems under External Disturbances

Complexity ◽  
2019 ◽  
Vol 2019 ◽  
pp. 1-13 ◽  
Author(s):  
Wonhee Kim ◽  
Chang Mook Kang ◽  
Young Seop Son ◽  
Chung Choo Chung
Keyword(s):  
Nonlinear Systems ◽  
Sliding Mode Control ◽  
Sliding Mode ◽  
Backstepping Control ◽  
State Variables ◽  
External Disturbances ◽  
Mode Control ◽  
Disturbance Cancellation ◽  
The Stability ◽  
Nonlinear Backstepping Control

A nonlinear backstepping control is proposed for the coupled normal form of nonlinear systems. The proposed method is designed by combining the sliding-mode control and backstepping control with a disturbance observer (DOB). The key idea behind the proposed method is that the linear terms of state variables of the second subsystem are lumped into the virtual input in the first subsystem. A DOB is developed to estimate the external disturbances. Auxiliary state variables are used to avoid amplification of the measurement noise in the DOB. For output tracking and unmatched disturbance cancellation in the first subsystem, the desired virtual input is derived via the backstepping procedure. The actual input in the second subsystem is developed to guarantee the convergence of the virtual input to the desired virtual input by using a sliding-mode control. The stability of the closed-loop is verified by using the input-to-state stable (ISS) property. The performance of the proposed method is validated via numerical simulations and an application to a vehicle system based on CarSim platform.

scholarly journals Observer-based adaptive neural network backstepping sliding mode control for switched fractional order uncertain nonlinear systems with unmeasured states

2021 ◽  
pp. 002029402110211
Author(s):  
Tao Chen ◽  
Damin Cao ◽  
Jiaxin Yuan ◽  
Hui Yang
Keyword(s):  
Neural Network ◽  
Nonlinear Systems ◽  
Sliding Mode Control ◽  
Fractional Order ◽  
Sliding Mode ◽  
Tracking Error ◽  
Adaptive Neural Network ◽  
Dynamic Surface ◽  
Mode Control ◽  
The Stability

This paper proposes an observer-based adaptive neural network backstepping sliding mode controller to ensure the stability of switched fractional order strict-feedback nonlinear systems in the presence of arbitrary switchings and unmeasured states. To avoid “explosion of complexity” and obtain fractional derivatives for virtual control functions continuously, the fractional order dynamic surface control (DSC) technology is introduced into the controller. An observer is used for states estimation of the fractional order systems. The sliding mode control technology is introduced to enhance robustness. The unknown nonlinear functions and uncertain disturbances are approximated by the radial basis function neural networks (RBFNNs). The stability of system is ensured by the constructed Lyapunov functions. The fractional adaptive laws are proposed to update uncertain parameters. The proposed controller can ensure convergence of the tracking error and all the states remain bounded in the closed-loop systems. Lastly, the feasibility of the proposed control method is proved by giving two examples.

Chattering-Free Finite-Time Stability of a Class of Fractional-Order Nonlinear Systems

2019 ◽  
Author(s):  
Bin Wang ◽  
Yangquan Chen ◽  
Ying Yang
Keyword(s):  
Nonlinear Systems ◽  
Sliding Mode Control ◽  
Fractional Order ◽  
Finite Time ◽  
Sliding Mode ◽  
Time Stability ◽  
External Disturbances ◽  
Finite Time Stability ◽  
Mode Control ◽  
Chattering Free

Abstract This paper studies the chattering-free finite-time control for a class of fractional-order nonlinear systems. First, a class of fractional-order nonlinear systems with external disturbances is presented. Second, a new finite-time terminal sliding mode control method is proposed for the stability control of a class of fractional-order nonlinear systems by combining the finite-time stability theory and sliding mode control scheme. Third, by designing a controller with a differential form and introducing the arc tangent function, the chattering phenomenon is well suppressed. Additionally, a controller is developed to resist external disturbances. Finally, numerical simulations are implemented to demonstrate the feasibility and validity of the proposed method.

Robust output tracking of nonlinear systems with transient improvement via funnel-based sliding mode control

2020 ◽  
Vol 42 (16) ◽  
pp. 3225-3233
Author(s):  
Mehdi Zahedi ◽  
Tahereh Binazadeh
Keyword(s):  
Nonlinear Systems ◽  
Sliding Mode Control ◽  
Sliding Mode ◽  
Model Uncertainties ◽  
External Disturbances ◽  
Output Tracking ◽  
Mode Control ◽  
Transient Improvement ◽  
The Face ◽  
Funnel Control

This paper studies a new procedure for robust tracking of nonlinear systems. This procedure is based on the combination of the sliding mode control and the funnel control, which in addition to the robust performance of the closed-loop system in the face of model uncertainties and/or external disturbances also leads to improvement of the characteristics of the transient responses. Using funnel control and the appropriate choice of the funnel can affect the convergence rate and overshoot. In this regard, a theorem has been presented and the effective performances of the suggested controller have been guaranteed in various respects based on exact mathematical analysis. Simulations have also been carried out to illustrate the efficiency of the proposed approach and to verify the theoretical achievements of the paper despite model uncertainties and external disturbances.

scholarly journals Sliding Mode Control of Flexible Articulated Manipulator Based on Robust Observer

2022 ◽  
Vol 2022 ◽  
pp. 1-10
Author(s):  
Yanghua Gao ◽  
Hailiang Lu
Keyword(s):  
Sliding Mode Control ◽  
Control Algorithm ◽  
Exponential Convergence ◽  
Sliding Mode ◽  
State Variables ◽  
External Disturbances ◽  
Convergence Conditions ◽  
Load Variations ◽  
Robust Observer ◽  
Mode Control

In this paper, a robust observer-based sliding mode control algorithm is proposed to address the modelling and measurement inaccuracies, load variations, and external disturbances of flexible articulated manipulators. Firstly, a sliding mode observer was designed with exponential convergence to observe system state accurately and to overcome the measuring difficulty of the state variables, unmeasurable quantities, and external disturbances. Next, a robust sliding mode controller was developed based on the observer, such that the output error of the system converges to zero in finite time. In this way, the whole system achieves asymptotic stability. Finally, the convergence conditions of the observer were theoretically analyzed to verify the convergence of the proposed algorithm, and simulation was carried out to confirm the effectiveness of the proposed method.

Robust sliding mode control of uncertain nonlinear systems with chattering alleviating scheme

2021 ◽  
pp. 2140042
Author(s):  
Bhausaheb B. Musmade ◽  
Balasaheb M. Patre
Keyword(s):  
Nonlinear Systems ◽  
Sliding Mode Control ◽  
Uncertain Systems ◽  
Sliding Mode ◽  
External Disturbance ◽  
Uncertain Nonlinear Systems ◽  
Model Uncertainties ◽  
External Disturbances ◽  
Controlled System ◽  
Mode Control

In this paper, a class of uncertain nonlinear systems is investigated and a sliding mode control (SMC) design is presented. The method is proposed for uncertain systems with model uncertainties, nonlinear dynamics and external disturbances. Using nominal system and related bounds of uncertainties, a chattering alleviating scheme is also proposed, which can ensure the robust SMC law. The performance and the significance of the controlled system are investigated under variation in system parameters and also in presence of an external disturbance. The simulation results indicate that performance of the proposed controller is effective compared to the existing controllers.

scholarly journals Robust Integral Terminal Sliding Mode Control for Quadrotor UAV with External Disturbances

2019 ◽  
Vol 2019 ◽  
pp. 1-10 ◽  
Author(s):  
Moussa Labbadi ◽  
Mohamed Cherkaoui
Keyword(s):  
Sliding Mode Control ◽  
Sliding Mode ◽  
Lyapunov Theory ◽  
Terminal Sliding Mode Control ◽  
External Disturbances ◽  
Terminal Sliding Mode ◽  
Mode Control ◽  
The Stability ◽  
The Right ◽  
Quadrotor System

The purpose of this paper is to solve the problem of controlling of the quadrotor exposed to external constant disturbances. The quadrotor system is partitioned into two parts: the attitude subsystem and the position subsystem. A new robust integral terminal sliding mode control law (RITSMC) is designed for stabilizing the inner loop and the quick tracking of the right desired values of the Euler angles. To estimate the disturbance displayed on the z-axis and to control the altitude position subsystem, an adaptive backstepping technique is proposed, while the horizontal position subsystem is controlled using the backstepping approach. The stability of the quadrotor subsystems is guaranteed by the Lyapunov theory. The effectiveness of the proposed methods is clearly comprehended through the obtained results of the various simulations effectuated on MATLAB/Simulink, and a comparison with another technique is presented.

Non-Linear Sliding Mode Control of a Tilting-Rotor Quadcopter

2017 ◽  
Author(s):  
Siddharth Sridhar ◽  
Rumit Kumar ◽  
Mohammadreza Radmanesh ◽  
Manish Kumar
Keyword(s):  
Sliding Mode Control ◽  
Sliding Mode ◽  
Control Technique ◽  
State Variables ◽  
Tracking Errors ◽  
External Disturbances ◽  
Tilt Rotor ◽  
Sliding Surfaces ◽  
Mode Control ◽  
Non Linear

A non-linear control of a tilt-rotor quadcopter using sliding mode technique is presented in this paper. The tilt-rotor quadcopters are a novel class of quadcopters with a servo motor installed on each arm that enables the quadcopter’s rotors to tilt to a particular angle. Using these additional tilt angles, this type of a quadcopter can be used to achieve desired trajectories with faster maneuvering and can handle external disturbances better than a conventional quadcopter. In this paper, sliding mode control technique is utilized for the pitch, roll and yaw motions for the quadcopter while an independent PD controller provides the tilt angles to the servo motors. The dynamic model of the tilt-rotor quadcopter is presented, based on which sliding surfaces were designed to minimize the tracking errors. Using the control inputs derived from these sliding surfaces, the state variables converge to their desired values in finite-time. Further, the non-linear sliding surface coefficients are obtained by stability analysis. Numerical simulation results demonstrate the performance and robustness against disturbances of this proposed sliding mode control technique.

scholarly journals Adaptive Sliding Mode Control Based on Uncertainty and Disturbance Estimator

2014 ◽  
Vol 2014 ◽  
pp. 1-10 ◽  
Author(s):  
Yue Zhu ◽  
Sihong Zhu
Keyword(s):  
Nonlinear Systems ◽  
Sliding Mode Control ◽  
Closed Loop ◽  
Sliding Mode ◽  
Adaptive Sliding Mode Control ◽  
External Disturbances ◽  
Adaptive Sliding Mode ◽  
Mode Control ◽  
Closed Loop Systems ◽  
Disturbance Estimator

This paper presents an original adaptive sliding mode control strategy for a class of nonlinear systems on the basis of uncertainty and disturbance estimator. The nonlinear systems can be with parametric uncertainties as well as unmatched uncertainties and external disturbances. The novel adaptive sliding mode control has several advantages over traditional sliding mode control method. Firstly, discontinuous sign function does not exist in the proposed adaptive sliding mode controller, and it is not replaced by saturation function or similar approximation functions as well. Therefore, chattering is avoided in essence, and the chattering avoidance is not at the cost of reducing the robustness of the closed-loop systems. Secondly, the uncertainties do not need to satisfy matching condition and the bounds of uncertainties are not required to be unknown. Thirdly, it is proved that the closed-loop systems have robustness to parameter uncertainties as well as unmatched model uncertainties and external disturbances. The robust stability is analyzed from a second-order linear time invariant system to a nonlinear system gradually. Simulation on a pendulum system with motor dynamics verifies the effectiveness of the proposed method.

Design of adaptive optimal robust control for two-flexible-link manipulators in the presence of matched uncertainties

2020 ◽  
pp. 107754632093202
Author(s):  
Hamid Reza Shafei ◽  
Mohsen Bahrami ◽  
Heidar Ali Talebi
Keyword(s):  
Sliding Mode Control ◽  
Sliding Mode ◽  
Flexible Link ◽  
External Disturbances ◽  
Terminal Sliding Mode ◽  
Control Approach ◽  
Mode Control ◽  
Nonsingular Terminal Sliding Mode ◽  
Control Scheme ◽  
The Stability

This study uses a comprehensive control approach to deal with the trajectory tracking problem of a two-flexible-link manipulator subjected to model uncertainties. Because the control inputs of two-flexible-link manipulators are less than their state variables, the proposed controller should be able to tackle the stated challenge. Practically speaking, there is only a single control signal for each joint, which can be used to suppress link deflections and control joint trajectories. To achieve this objective, a novel optimal robust control scheme, with an updated gain under the adaptive law, has been developed in this work for the first time. In this regard, a nonsingular terminal sliding mode control approach is used as the robust controller and a control Lyapunov function is used as the optimal control law, to benefit from the advantages of both methods. To systematically deal with system uncertainties, an adaptive law is used to update the gain of nonsingular terminal sliding mode control. The advantage of this approach over the existing methods is that it not only can robustly and stably control an uncertain nonlinear system against external disturbances but also can optimally solve a quadratic cost function (e.g. minimization of control effort). The Lyapunov stability theory has been applied to verify the stability of the proposed approach. Moreover, to show the superiority of this method, the computer simulation results of the proposed method have been compared with those of an adaptive sliding mode control scheme. This comparison shows that the presented approach is capable of optimizing the control inputs while achieving the stability of the examined two-flexible-link manipulator in the presence of model uncertainties and external disturbances.

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