Robust adaptive sliding mode control for a human-driven knee joint orthosis

2018 ◽  
Vol 45 (3) ◽  
pp. 379-389 ◽  
Author(s):  
Rihab Bkekri ◽  
Anouar Benamor ◽  
Mohamed Amine Alouane ◽  
Georges Fried ◽  
Hassani Messaoud
Keyword(s):  
Knee Joint ◽  
Lyapunov Stability ◽  
Stability Theory ◽  
Sliding Mode ◽  
Lyapunov Stability Theory ◽  
Parameter Uncertainties ◽  
External Disturbances ◽  
Content Type ◽  
Adaptive Sliding Mode ◽  
Robust Adaptive

Purpose Assistive technology products are designed to provide additional accessibility to individuals who have physical or cognitive difficulties, impairments and disabilities. The purpose of this paper is to deal with the control of a knee joint orthosis intended to be used for rehabilitation and assistive purpose; this control aims to reduce the influence of the uncertainties and eliminating the external disturbances in the system. Design/methodology/approach This paper deals with the robust adaptive sliding mode controller (ASMC) of human-driven knee joint orthosis system with mismatched uncertainties and external disturbances. The shank-orthosis system has been modeled and its parameters have been identified. This control reduces the effect of parameter uncertainties and external disturbances on the system performance and improves the system robustness as results. The ASMC was designed to offer the possibility to track the state of the reference model. Moreover, the Lyapunov stability theory was used to study the asymptotical stability of the ASMC. Findings The advantage of the robust ASMC method is the tracking precision and reducing the required time for eliminating external disturbances and uncertainties. The experimental results show in real-time in terms of stability and present that the advantages of this control approach are the position tracking and robustness. Originality/value In this paper, to deal with the parameter uncertainties of the human-driven knee joint orthosis, an ASMC was successfully applied based on sliding mode and Lyapunov stability theory. It has good dynamic response and tracking performance. Besides, the adaptive algorithm is simple, easy to achieve and has good adaptability and robustness against the parameter variations and external disturbances. The design technique is simple and efficient. The development of this control takes into consideration the perturbation, allowing to track a desired trajectory.

Chaos control of the power system via sliding mode based on fuzzy supervisor

2017 ◽  
Vol 10 (1) ◽  
pp. 68-79 ◽  
Author(s):  
Ahmad Sarani Ali Abadi ◽  
Saeed Balochian
Keyword(s):  
Sliding Mode Control ◽  
Power System ◽  
Lyapunov Stability ◽  
Stability Theory ◽  
Closed Loop ◽  
Sliding Mode ◽  
Lyapunov Stability Theory ◽  
Content Type ◽  
Mode Control ◽  
Fuzzy Supervisor

Purpose The purpose of this paper is to address the problem of control in a typical chaotic power system. Chaotic oscillations cannot only extremely endanger the stabilization of the power system but they can also not be controlled by adding the traditional controllers. So, the sliding mode control based on a fuzzy supervisor can sufficiently ensure perfect tracking and controlling in the presence of uncertainties. Closed-loop stability is proved using the Lyapunov stability theory. The simulation results show the effectiveness of the proposed method in damping chaotic oscillations of the power system, eliminating control signal chattering and also show less control effort in comparison with the methods considered in previous literatures. Design/methodology/approach The sliding mode control based on a fuzzy supervisor can sufficiently ensure perfect tracking and controlling in the presence of uncertainties. Closed-loop stability is proved using the Lyapunov stability theory. Findings Closed-loop stability is proved using the Lyapunov stability theory. The simulation results show the effectiveness of the proposed method in damping chaotic oscillations of power system, eliminating control signal chattering and also less control effort in comparison with the methods considered in previous literatures. Originality/value Main contributions of the paper are as follows: the chaotic behavior of power systems with two uncertainty parameters and tracking reference signal for the control of generator angle and the controller signal are discussed; designing sliding mode control based on a fuzzy supervisor in order to practically implement for the first time; while the generator speed is constant, the proposed controller will enable the power system to go in any desired trajectory for generator angle at first time; stability of the closed-loop sliding mode control based on the fuzzy supervisor system is proved using the Lyapunov stability theory; simulation of the proposed controller shows that the chattering is low control signal.

scholarly journals Robust Synchronization of Hyperchaotic Systems with Uncertainties and External Disturbances

2014 ◽  
Vol 2014 ◽  
pp. 1-8 ◽  
Author(s):  
Qing Wang ◽  
Yongguang Yu ◽  
Hu Wang
Keyword(s):  
Numerical Simulations ◽  
Lyapunov Stability ◽  
Stability Theory ◽  
Lyapunov Stability Theory ◽  
Convergence Speed ◽  
External Disturbances ◽  
Adaptive Controllers ◽  
Robust Synchronization ◽  
Hyperchaotic Systems

The robust synchronization of hyperchaotic systems with uncertainties and external disturbances is investigated. Based on the Lyapunov stability theory, the appropriate adaptive controllers and parameter update laws are designed to achieve the synchronization of uncertain hyperchaotic systems. The robust synchronization of two hyperchaotic Chen systems is taken as an example to verify the feasibility of the presented schemes. The size of the subcontroller gain’s influences on the convergence speed is discussed. Finally, numerical simulations are given to demonstrate the effectiveness of the proposed synchronization schemes.

On adaptive sliding mode control for improved quadrotor tracking

2017 ◽  
Vol 24 (14) ◽  
pp. 3219-3230 ◽  
Author(s):  
Sudhir Nadda ◽  
A Swarup
Keyword(s):  
Sliding Mode Control ◽  
Control Method ◽  
Sliding Mode ◽  
Lyapunov Stability Theory ◽  
Adaptive Method ◽  
Adaptation Strategy ◽  
Adaptive Sliding Mode Control ◽  
Parameter Uncertainties ◽  
External Disturbances ◽  
Mode Control

The tracking control of a quadrotor has been considered in this paper. The application of sliding mode control provides robustness against parametric uncertainties, but it requires knowledge of the upper bounds of uncertainties. An adaptation strategy has been proposed to implement sliding mode control, which does not require the upper bound of the uncertainties. The adaptive control law is derived on the basis of Lyapunov stability theory, which guarantees the tracking performance. The adaptation can be tuned faster by proper tuning, and convergence with good tracking can be achieved. The proposed adaptive method has improved robustness and provided simpler implementation. Through an illustrative simulation example, the performance of the proposed control method is presented and also compared with classical sliding mode control from the literature. It is demonstrated that the performance of quadrotor altitude tracking and convergence has been considerably improved while maintaining stability, even in presence of external disturbances and parameter uncertainties.

Robust adaptive attitude manoeuvre control with finite-time convergence for a flexible spacecraft

2016 ◽  
Vol 40 (2) ◽  
pp. 425-435 ◽  
Author(s):  
Chenxing Zhong ◽  
Liping Wu ◽  
Jian Guo ◽  
Yu Guo ◽  
Zhiyong Chen
Keyword(s):  
Finite Time ◽  
Sliding Mode ◽  
Coupling Effect ◽  
Lyapunov Stability Theory ◽  
Flexible Spacecraft ◽  
Practical Case ◽  
External Disturbances ◽  
Terminal Sliding Mode ◽  
Chattering Free ◽  
Robust Adaptive

This paper investigates a finite-time attitude manoeuvre control problem for a flexible spacecraft subject to bounded external disturbances. A robust discontinuous finite-time controller with terminal sliding mode control is designed to solve this problem provided that the disturbances and the coupling effect of flexible modes are bounded with a known boundary. The controller is further enhanced by an adaptive scheme to deal with the more practical case that the boundary is unknown. The enhanced version is continuous and chattering-free. The results are rigorously proved using the Lyapunov stability theory. The effectiveness and robustness of the proposed controllers are demonstrated by numerical simulation.

Robust Adaptive Controller Design for a Quadrotor Helicopter

2013 ◽  
Vol 284-287 ◽  
pp. 2296-2300 ◽  
Author(s):  
Kuang Shine Yang ◽  
Chi Cheng Cheng
Keyword(s):  
Attitude Control ◽  
Degrees Of Freedom ◽  
Controller Design ◽  
Sliding Mode ◽  
Underactuated System ◽  
Parameter Uncertainties ◽  
Unknown Parameters ◽  
External Disturbances ◽  
Quadrotor Helicopter ◽  
Robust Adaptive

The quadrotor helicopter is designed to easily move in particular environments because it can take off and land in limited space and easily hover at a fixed location. For this reason, a robust adaptive sliding mode controller is developed to control of a quadrotor helicopter in the presence of external disturbances and parameter uncertainties. The quadrotor helicopter system is a typical underactuated system, which has fewer independent control actuators than degrees of freedom to be controlled. The main contribution here is to afford simulation and verification for the quadrotor helicopter flight controller under the assumption of unknown parameters. By utilizing the Lyapunov stability theorem, we can achieve asymptotic tracking of desired reference commands for the quadrotor helicopter, which is subject to both external disturbances and parametric uncertainties. From the simulation results, the controller was sufficient to achieve position and attitude control of the quadrotor helicopter system, which permits possible real time applications in the near future.

scholarly journals Trajectory tracking of a mobile robot using adaptive sliding mode control

2021 ◽  
Author(s):  
Seyyed Mohammad Hosseini Rostami ◽  
Fatemeh Jahangiri
Keyword(s):  
Sliding Mode Control ◽  
Sliding Mode ◽  
Parametric Uncertainty ◽  
Adaptive Sliding Mode Control ◽  
Control Law ◽  
External Disturbances ◽  
Adaptive Sliding Mode ◽  
Mode Control ◽  
Angular Velocities ◽  
Robust Adaptive

Abstract The purpose of this paper is to design a control system for a mobile four-wheeled robot, whose task is to achieve stability and proper operation in the execution of commands. As a result of the nonlinear dynamics, structural and parametric uncertainty of this robot, various control approaches are used in order to achieve stability, proper performance, minimize modeling errors and uncertainties, etc. By adjusting linear and angular velocities in the presence of external disturbances and parametric uncertainty, this algorithm is able to follow a predetermined trajectory based on the information contained in the signals received by the sensor from the trajectory.. In previous articles, the upper bound of uncertainty was assumed to be known. This paper makes the assumption that the upper band of uncertainty and disturbances in robotic systems is unknown, since, in many cases, we cannot know the extent of these uncertainties in practice. In our recent paper, we generalized the sliding mode control law and proved its effectiveness, so that by including an adaptive part to the control law, we transformed it into a robust-adaptive sliding mode control, and we could estimate the upper band uncertainties online based on these adaptive laws. This typology can be expressed as a distinct theorem with stable results. Simulations with MATLAB software demonstrate that the controller ensures optimal performance under external disturbances and parametric uncertainty with less fluctuations.

Design and Analysis of Non-linear Controller for a Standalone PV System using Lyapunov Stability Theory

2021 ◽  
pp. 1-22
Author(s):  
Narendra Kumar ◽  
Aman Sharma
Keyword(s):  
Lyapunov Stability ◽  
Stability Theory ◽  
Sliding Mode ◽  
Equilibrium Points ◽  
Lyapunov Stability Theory ◽  
Maximum Power ◽  
Hill Climbing ◽  
Sliding Mode Controller ◽  
Nonlinear Controller ◽  
Pv System

Abstract This paper presents Lyapunov Stability Theory based Nonlinear Controller Design for a Standalone PV System. The comparative analysis of different nonlinear controllers is also carried out . Due to the nonlinear characteristics of photovoltaic systems, conventional Hill-Climbing methods like Perturbate and Observe and Incremental Conductance do not show reliable tracking of Maximum Power under various uncertainties. Therefore, these methods require nonlinear tools to meet the control objectives and design specifications. Out of various nonlinear controlling techniques, the one presented in this paper is the Sliding Mode Approach for Maximum Power Point Tracking (MPPT). In context of Lyapunov Stability Theory, sliding mode approach uses a switching manifold. In this approach, the system trajectories are made to follow the sliding surface and to remain there forever to ensure the stability of equilibrium points. Two types of Sliding Mode controllers have been simulated namely Conventional - Sliding Mode Controller (CSMC) and Terminal - Sliding Mode Controller (TSMC). The results are analyzed and compared scientifically on various performance parameters including, duty cycle ratio, ideal and PV output power and time taken for error convergence, under varying dynamic conditions. All the control algorithms are developed in MATLAB/Simulink.

Robust Adaptive Tracking Control of Uncertain Rehabilitation Exoskeleton Robot

2019 ◽  
Vol 141 (12) ◽  
Author(s):  
Brahim Brahmi ◽  
Abdelkrim Brahmi ◽  
Maarouf Saad ◽  
Guy Gauthier ◽  
Mohammad Habibur Rahman
Keyword(s):  
Sliding Mode ◽  
Robust Adaptive Control ◽  
Human Robot Interaction ◽  
Adaptive Sliding Mode Control ◽  
Control Law ◽  
Parameter Uncertainties ◽  
External Disturbances ◽  
Control Approach ◽  
Exoskeleton Robot ◽  
Robust Adaptive

Abstract Rehabilitation robots have become an influential tool in physiotherapy treatment because they are able to provide intensive rehabilitation treatment over a long period of time. However, this technology still suffers from various problems such as dynamic uncertainties, external disturbances, and human–robot interaction. In this paper, we propose a robust adaptive control approach of an exoskeleton robot with an unknown dynamic model and external disturbances. First, the dynamics of the exoskeleton's arm is presented. Then, we design a robust adaptive sliding mode control in which the parameter uncertainties and the disturbances are estimated by the adaptive update methods. The proposed control ensures a good tracking of the system with a finite time convergence of sliding surface to zero. Throughout this paper, the designed control law and the global stability analysis are formulated and demonstrated based on the appropriate choice of the candidate Lyapunov function. The experimental and comparative results, performed for seven degrees-of-freedom (DOFs) exoskeleton arm with three healthy subjects to track a passive rehabilitation motion, confirm the effectiveness and robustness of the proposed control law compared with conventional adaptive approach.

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