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.

Robust adaptive tracking control for uncertain nonholonomic mobile manipulator

2021 ◽  
pp. 095965182110277
Author(s):  
Abdelkrim Brahmi ◽  
Maarouf Saad ◽  
Brahim Brahmi ◽  
Ibrahim El Bojairami ◽  
Guy Gauthier ◽  
...  
Keyword(s):  
Control Method ◽  
Sliding Mode ◽  
Robust Adaptive Control ◽  
Convergence Time ◽  
Adaptive Sliding Mode Control ◽  
Mobile Manipulator ◽  
Control Law ◽  
Adaptive Tracking Control ◽  
Robust Adaptive ◽  
Manipulator Robot

In the research put forth, a robust adaptive control method for a nonholonomic mobile manipulator robot, with unknown inertia parameters and disturbances, was proposed. First, the description of the robot’s dynamics model was developed. Thereafter, a novel adaptive sliding mode control was designed, to which all parameters describing involved uncertainties and disturbances were estimated by the adaptive update technique. The proposed control ensures a relatively good system tracking, with all errors converging to zero. Unlike conventional sliding mode controls, the suggested is able to achieve superb performance, without resulting in any chattering problems, along with an extremely fast system trajectories convergence time to equilibrium. The aforementioned characteristics were attainable upon using an innovative reaching law based on potential functions. Furthermore, the Lyapunov approach was used to design the control law and to conduct a global stability analysis. Finally, experimental results and comparative study collected via a 05-DoF mobile manipulator robot, to track a given trajectory, showing the superior efficiency of the proposed control law.

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.

A Robust Adaptive Sliding Mode Control Method for Attitude Control of the Quad-Rotor

2014 ◽  
Vol 852 ◽  
pp. 391-395
Author(s):  
Yong Gao ◽  
Zhao Qing Song ◽  
Xiao Liu
Keyword(s):  
Attitude Control ◽  
Control Method ◽  
Sliding Mode ◽  
Tracking Error ◽  
Robust Adaptive Control ◽  
Adaptive Sliding Mode Control ◽  
Control Law ◽  
Unknown Disturbances ◽  
Robust Adaptive ◽  
Uncertainty Parameters

Quad-rotor is a multi-variable and strong coupling system which has nonlinear and uncertainties. According to the quad-rotor, a dynamic model of attitude which included uncertainty parameters and unknown disturbances was established. The tracking error state was used to design a slide mode surface, and a Lyapunov function which includes slide mode surface and unknown parameter was built. Further more, a robust adaptive control law was designed. At last, the designed control law was simulated, and the results justify the feasibility of the proposed control law.

scholarly journals Robust adaptive global nonlinear sliding mode controller for a quadrotor under external disturbances and uncertainties

2020 ◽  
Vol 12 (11) ◽  
pp. 168781402097523
Author(s):  
Moussa Labbadi ◽  
Yassine El Houm ◽  
Ahmed Abbou ◽  
Mohamed Cherkaoui
Keyword(s):  
Sliding Mode ◽  
Upper Bounds ◽  
Initial Time ◽  
Control Law ◽  
Sliding Mode Controller ◽  
External Disturbances ◽  
Control Approach ◽  
Adaptive Laws ◽  
Robust Adaptive ◽  
The Stability

The present paper proposes an adaptive global nonlinear sliding mode controller (AGNSMC) for the tracking problem of a quadrotor subjected to external disturbances. In order to eliminate the reaching phase and to guarantee the sliding mode of the quadrotor states in the initial time, a novel control law is developed. The upper bounds of disturbances affected the quadrotor dynamics are rejected based on adaptive laws for the both attitude and position subsystem. The tracking performance is enhanced by using the suggested controller. The stability of quadrotor is guaranteed and the global sliding mode surfaces converge to origin values in a finite time. To show the robustness of the proposed control approach against the external disturbances, simulation results are presented and compared with the results of the super-twisting-integral sliding mode controller.

scholarly journals Adaptive Sliding Mode Control Using Robust Feedback Compensator for MEMS Gyroscope

2013 ◽  
Vol 2013 ◽  
pp. 1-10
Author(s):  
Juntao Fei ◽  
Dan Wu
Keyword(s):  
Adaptive Control ◽  
Sliding Mode Control ◽  
Sliding Mode ◽  
Robust Adaptive Control ◽  
Adaptive Sliding Mode Control ◽  
External Disturbances ◽  
Mems Gyroscope ◽  
Adaptive Sliding Mode ◽  
Mode Control ◽  
Robust Adaptive

An adaptive sliding mode control using robust feedback compensator is presented for a MEMS gyroscope in the presence of external disturbances and parameter uncertainties. An adaptive controller with a robust term is used to improve the robustness of the control system and compensate the system nonlinearities. The proposed robust adaptive control can estimate the angular velocity and all the system parameters including damping and stiffness coefficients in the Lyapunov framework. In addition, standard adaptive control scheme without robust algorithm is compared with the proposed robust adaptive scheme in the aspect of numerical simulation and algorithm derivation. Numerical simulations show that the robust adaptive control has better robustness in the presence of external disturbances than the standard adaptive control.

scholarly journals Adaptive output feedback integral sliding mode attitude tracking control of spacecraft without unwinding

2017 ◽  
Vol 9 (7) ◽  
pp. 168781401771040 ◽  
Author(s):  
Anuchit Jitpattanakul ◽  
Chutiphon Pukdeboon
Keyword(s):  
Output Feedback ◽  
Tracking Control ◽  
Sliding Mode ◽  
Control Technique ◽  
Control Law ◽  
Parameter Uncertainties ◽  
External Disturbances ◽  
Integral Sliding Mode ◽  
Attitude Tracking ◽  
Attitude Tracking Control

This article studies an output feedback attitude tracking control problem for rigid spacecraft in the presence of parameter uncertainties and external disturbances. First, an anti-unwinding attitude control law is designed using the integral sliding mode control technique to achieve accurate tracking responses and robustness against inertia uncertainties and external disturbances. Next, the derived control law is combined with a suitable tuning law to relax the knowledge about the bounds of uncertainties and disturbances. The stability results are rigorously proved using the Lyapunov stability theory. In addition, a new finite-time sliding mode observer is developed to estimate the first time derivative of attitude. A new adaptive output feedback attitude controller is designed based on the estimated results, and angular velocity measurements are not required in the design process. A Lyapunov-based analysis is provided to demonstrate the uniformly ultimately bounded stability of the observer errors. Numerical simulations are given to illustrate the effectiveness of the proposed control method.

scholarly journals Joint torque control of flexible joint robots based on sliding mode technique

2019 ◽  
Vol 16 (3) ◽  
pp. 172988141984671 ◽  
Author(s):  
Gen-Liang Xiong ◽  
Hai-Chu Chen ◽  
Jing-Xin Shi ◽  
Fa-Yun Liang
Keyword(s):  
Sliding Mode ◽  
Joint Stiffness ◽  
Torque Control ◽  
Joint Torque ◽  
Parameter Uncertainties ◽  
External Disturbances ◽  
Control Approach ◽  
Flexible Joint Robots ◽  
Mode Technique ◽  
Sliding Mode Technique

For robots with flexible joints, the joint torque dynamics makes it difficult to control. An effective solution is to carry out a joint torque controller with fast enough dynamic response. This article is dedicated to design such a torque controller based on sliding mode technique. Three joint torque control approaches are proposed: (1) The proportional-derivative (PD)-type controller has some degree of robustness by properly selecting the control gains. (2) The direct sliding mode control approach which fully utilizes the physical properties of electric motors. (3) The sliding mode estimator approach was proposed to compensate the parameter uncertainties and the external disturbances of the joint torque system. These three joint torque controllers are tested and verified by the simulation studies with different reference torque trajectories and under different joint stiffness.

A New Robust Adaptive Sliding Mode Control for Discrete-Time Systems With Time-Varying State Delay

2021 ◽  
Vol 12 (2) ◽  
pp. 132-153
Author(s):  
Chakib Ben Njima ◽  
Anouar Benamor ◽  
Hassani Messaoud
Keyword(s):  
Sliding Mode ◽  
Uncertain System ◽  
Control Mode ◽  
Adaptive Sliding Mode Control ◽  
Linear Matrix ◽  
Control Law ◽  
Robust Adaptive ◽  
Time Systems ◽  
Varying Delay

This article proposes a novel robust adaptive sliding control mode law for time unknown varying delay in state uncertain systems. In this work, the upper limit of disruption and uncertainty is assumed to be unknown. The model is adjusted so that the system looks like a certain one with unknown added disturbances on the bounds of which are unknown too. Accordingly, new control law for this kind of systems has been defined based on a Lypunov function choice. The main results of this paper are that the conditions for the existence of linear sliding surfaces are derived within the linear matrix inequalities (LMIs) framework by employing the free weighting matrices and the determination of the control law based on a sliding surface will converge to zero. This proposed approach has been validated in simulation on an uncertain system with comparative study proved the efficiency of the proposed resulting methodology after has been validated in real system.

scholarly journals Robust Adaptive Control andL2Disturbance Attenuation for Uncertain Hamiltonian Systems with Time Delay

2013 ◽  
Vol 2013 ◽  
pp. 1-10 ◽  
Author(s):  
Weiwei Sun ◽  
Guochen Pang ◽  
Pan Wang ◽  
Lianghong Peng
Keyword(s):  
Adaptive Control ◽  
Time Delay ◽  
Hamiltonian Systems ◽  
Robust Adaptive Control ◽  
Disturbance Attenuation ◽  
Control Law ◽  
External Disturbances ◽  
Time Varying Delay ◽  
Closed Loop Systems ◽  
Robust Adaptive

This paper deals with the robust stabilizability andL2disturbance attenuation for a class of time-delay Hamiltonian control systems with uncertainties and external disturbances. Firstly, the robust stability of the given systems is studied, and delay-dependent criteria are established based on the dissipative structural properties of the Hamiltonian systems and the Lyapunov-Krasovskii (L-K) functional approach. Secondly, the problem ofL2disturbance attenuation is considered for the Hamiltonian systems subject to external disturbances. An adaptive control law is designed corresponding to the time-varying delay pattern involved in the systems. It is shown that the closed-loop systems under the feedback control law can guarantee theγ-dissipative inequalities be satisfied. Finally, two numerical examples are provided to illustrate the theoretical developments.

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