scholarly journals Linear Active Disturbance Rejection Control of a Two-Degrees-of-Freedom Manipulator

2020 ◽  
Vol 2020 ◽  
pp. 1-19 ◽  
Author(s):  
Dawei Liu ◽  
Qinhe Gao ◽  
Zhixiang Chen ◽  
Zhihao Liu
Keyword(s):  
Trajectory Tracking ◽  
Disturbance Rejection ◽  
Degrees Of Freedom ◽  
Closed Loop ◽  
Active Disturbance Rejection Control ◽  
Dynamic Coupling ◽  
Closed Loop System ◽  
Two Degrees Of Freedom ◽  
Active Disturbance Rejection ◽  
Disturbance Rejection Control

This paper presents linear active disturbance rejection control (LADRC) for a two-degrees-of-freedom (2-DOF) manipulator system to achieve trajectory tracking. The system is widely used in engineering applications and exhibits the characteristics of high nonlinearity, strong coupling, and large uncertainty with two inputs and two outputs. First, the problem of dynamic coupling in the model of the 2-DOF manipulator is addressed by considering the dynamic coupling, model uncertainties, and external disturbances as total disturbances. Second, a linear extended state observer is designed to estimate the total disturbances, while a linear state error feedback control law is designed to compensate these disturbances. The main contribution is that the stability of the closed-loop system with two inputs and two outputs is analyzed, and the relationship between the performance of the closed-loop system and the controller parameters is established. The joint simulation of SolidWorks and Matlab/Simulink is conducted. The simulation and experimental results clearly indicate the superiority of LADRC over the PID for trajectory tracking and dynamic performance.

Non-linear active disturbance rejection control for upper limb rehabilitation exoskeleton

2020 ◽  
pp. 095965182095457
Author(s):  
Sumit Aole ◽  
Irraivan Elamvazuthi ◽  
Laxman Waghmare ◽  
Balasaheb Patre ◽  
Fabrice Meriaudeau
Keyword(s):  
Upper Limb ◽  
Trajectory Tracking ◽  
Disturbance Rejection ◽  
Active Disturbance Rejection Control ◽  
Upper Limb Rehabilitation ◽  
Active Disturbance Rejection ◽  
Disturbance Rejection Control ◽  
Flexion Extension ◽  
Non Linear ◽  
Limb Rehabilitation

Trajectory tracking in upper limb rehabilitation exercises is utilized for repeatability of joint movement to improve the patient’s recovery in the early stages of rehabilitation. In this article, non-linear active disturbance rejection control as a combination of non-linear extended-state observer and non-linear state error feedback is used for the sinusoidal trajectory tracking control of the two-link model of an upper limb rehabilitation exoskeleton. The two links represent movements like flexion/extension for both the shoulder joint and the elbow joint in the sagittal plane. The Euler–Lagrange method was employed to acquire a dynamic model of an upper limb rehabilitation exoskeleton. To examine the efficacy and robustness of the proposed method, four disturbances cases in simulation studies with 20% parameter variation were applied. It was found that the non-linear active disturbance rejection control is robust against disturbances and achieves better tracking as compared to proportional–integral–derivative and existing conventional active disturbance rejection control method.

On the Linear Control of Underactuated Nonlinear Systems Via Tangent Flatness and Active Disturbance Rejection Control: The Case of the Ball and Beam System

2016 ◽  
Vol 138 (10) ◽  
Author(s):  
Mario Ramírez-Neria ◽  
Hebertt Sira-Ramírez ◽  
Rubén Garrido-Moctezuma ◽  
Alberto Luviano-Juárez
Keyword(s):  
Equilibrium Point ◽  
Trajectory Tracking ◽  
Disturbance Rejection ◽  
Observer Design ◽  
Active Disturbance Rejection Control ◽  
Tracking Tasks ◽  
Active Disturbance Rejection ◽  
Beam System ◽  
Disturbance Rejection Control ◽  
Ball And Beam System

In this paper, a systematic procedure for controller design is proposed for a class of nonlinear underactuated systems (UAS), which are non-feedback linearizable but exhibit a controllable (flat) tangent linearization around an equilibrium point. Linear extended state observer (LESO)-based active disturbance rejection control (ADRC) is shown to allow for trajectory tracking tasks involving significantly far excursions from the equilibrium point. This is due to local approximate estimation and compensation of the nonlinearities neglected by the linearization process. The approach is typically robust with respect to other endogenous and exogenous uncertainties and disturbances. The flatness of the tangent model provides a unique structural property that results in an advantageous low-order cascade decomposition of the LESO design, vastly improving the attenuation of noisy and peaking components found in the traditional full order, high gain, observer design. The popular ball and beam system (BBS) is taken as an application example. Experimental results show the effectiveness of the proposed approach in stabilization, as well as in perturbed trajectory tracking tasks.

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