scholarly journals Research on a Nonlinear Robust Adaptive Control Method of the Elbow Joint of a Seven-Function Hydraulic Manipulator Based on Double-Screw-Pair Transmission

2014 ◽  
Vol 2014 ◽  
pp. 1-11
Author(s):  
Gaosheng Luo ◽  
Jiawang Chen ◽  
Linyi Gu
Keyword(s):  
Adaptive Control ◽  
Elbow Joint ◽  
Control Method ◽  
Dynamic Performance ◽  
Robust Adaptive Control ◽  
Reference Trajectory ◽  
Parameter Uncertainties ◽  
External Disturbances ◽  
Hydraulic Manipulator ◽  
Robust Adaptive

A robust adaptive control method with full-state feedback is proposed based on the fact that the elbow joint of a seven-function hydraulic manipulator with double-screw-pair transmission features the following control characteristics: a strongly nonlinear hydraulic system, parameter uncertainties susceptible to temperature and pressure changes of the external environment, and unknown outer disturbances. Combined with the design method of the back-stepping controller, the asymptotic stability of the control system in the presence of disturbances from uncertain systematic parameters and unknown external disturbances was demonstrated using Lyapunov stability theory. Based on the elbow joint of the seven-function master-slave hydraulic manipulator for the 4500 m Deep-Sea Working System as the research subject, a comparative study was conducted using the control method presented in this paper for unknown external disturbances. Simulations and experiments of different unknown outer disturbances showed that (1) the proposed controller could robustly track the desired reference trajectory with satisfactory dynamic performance and steady accuracy and that (2) the modified parameter adaptive laws could also guarantee that the estimated parameters are bounded.

Robust Adaptive Control of Antagonistic Tendon-Driven Joint in the Presence of Parameter Uncertainties and External Disturbances

2017 ◽  
Vol 139 (10) ◽  
Author(s):  
Hongqian Lu ◽  
Xu Zhang ◽  
Xianlin Huang
Keyword(s):  
Adaptive Control ◽  
Control Method ◽  
Controller Design ◽  
Block Diagram ◽  
Viscous Friction ◽  
Robust Adaptive Control ◽  
Parameter Uncertainties ◽  
Closed Loop Systems ◽  
Nonlinear Tracking ◽  
Robust Adaptive

The design of nonlinear tracking controller for antagonistic tendon-driven joint has garnered considerable attention, whereas many existing control methodologies are impractical in the real-time applications due to complexity of computations. In this work, a robust adaptive control method for controlling antagonistic tendon-driven joint is mainly studied by combining adaptive control with mapping filtered forwarding technique. To enhance the robustness of the closed-loop systems, the true viscous friction coefficients are not needed to be known in our controller design. Typically, to tackle the problem of “explosion of complexity,” filters are introduced to bridge the virtual controls such that the controller is decomposed into several submodules. Mappings and their analytic derivatives are computed by these filters, and the mathematical operations of nonlinearities are greatly simplified. The block diagram of this controller of tendon-driven joint is provided, and controller performances are validated through simulations.

Part 1: robust adaptive control of quadrotor with disturbance observer

2021 ◽  
Vol ahead-of-print (ahead-of-print) ◽  
Author(s):  
Nigar Ahmed ◽  
Abid Raza ◽  
Rameez Khan
Keyword(s):  
Adaptive Control ◽  
Disturbance Observer ◽  
Control Method ◽  
Sliding Mode ◽  
External Disturbance ◽  
Robust Adaptive Control ◽  
External Disturbances ◽  
Content Type ◽  
Control Objective ◽  
Robust Adaptive

Purpose The aim of this paper is to design a nonlinear disturbance observer-based control (DOBC) method obtained by patching a control method developed using a robust adaptive technique and a DO. Design/methodology/approach For designing a DOBC, initially a class of nonlinear system is considered with an external disturbance. First, a DO is designed to estimate the external disturbances. This estimate is combined with the controller to reject the disturbances and obtain the desired control objective. For designing a controller, the robust sliding mode control theory is used. Furthermore, instead of using a constant switching gain, an adaptive gain tuning criterion is designed using Lyapunov candidate function. To investigate the stability and effectiveness of the developed DOBC, stability analysis and simulation study are presented. Findings The major findings of this paper include the criteria of designing the robust adaptive control parameters and investigating the disturbance rejection when robust adaptive control based DOBC is developed. Practical implications In practice, the flight of quadrotor is affected by different kind of external disturbances, thus leading to the change in dynamics. Hence, it is necessary to design DOBCs based on robust adaptive controllers such that the quadrotor model adapts to the change in dynamics, as well as nullify the effect of disturbances. Originality/value Designing DOBCs based on robust control method is a common practice; however, the robust adaptive control method is rarely developed. This paper contributes in the domain of DOBC based on robust adaptive control methods such that the behavior of controller varies with the change in dynamics occurring due to external disturbances.

scholarly journals Robust Adaptive Control for Nonlinear Aircraft System with Uncertainties

2020 ◽  
Vol 10 (12) ◽  
pp. 4270
Author(s):  
Jiao Chen ◽  
Jiangyun Wang ◽  
Weihong Wang
Keyword(s):  
Adaptive Control ◽  
High Frequency ◽  
Control Method ◽  
Longitudinal Direction ◽  
Flight Simulation ◽  
Robust Adaptive Control ◽  
High Frequency Oscillation ◽  
Robust Adaptive ◽  
Aircraft System ◽  
Fast Adaptation

Model reference adaptive control (MRAC) schemes are known as an effective method to deal with system uncertainties. High adaptive gains are usually needed in order to achieve fast adaptation. However, this leads to high-frequency oscillation in the control signal and may even make the system unstable. A robust adaptive control architecture was designed in this paper for nonlinear aircraft dynamics facing the challenges of input uncertainty, matched uncertainty, and unmatched uncertainty. By introducing a robust compensator to the MRAC framework, the high-frequency components in the control response were eliminated. The proposed control method was applied to the longitudinal-direction motion control of a nonlinear aircraft system. Flight simulation results demonstrated that the proposed robust adaptive method was able to achieve fast adaptation without high-frequency oscillations, and guaranteed transient performance.

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.

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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