scholarly journals A second order time-varying parameters extended state observer based on hyperbolic sine function for uncertain nonlinear disturbances

2015 ◽  
Author(s):  
Hongguo Yu ◽  
Zhongjian Kang ◽  
Yao Chen
Keyword(s):  
State Observer ◽  
Extended State Observer ◽  
Time Varying ◽  
Sine Function ◽  
Extended State ◽  
Varying Parameters ◽  
Hyperbolic Sine ◽  
Nonlinear Disturbances ◽  
Time Varying Parameters ◽  
Hyperbolic Sine Function

Dual extended state observer-based backstepping control of electro-hydraulic servo systems with time-varying output constraints

2019 ◽  
Vol 42 (5) ◽  
pp. 1070-1080
Author(s):  
Guichao Yang
Keyword(s):  
Hydraulic System ◽  
State Observer ◽  
Extended State Observer ◽  
Time Varying ◽  
Extended State ◽  
Servo Systems ◽  
Output Constraints ◽  
Unknown Disturbances ◽  
Hydraulic Servo ◽  
Mismatched Disturbances

In this paper, a novel nonlinear robust controller ensuring time-varying output constraints for the double-rod hydraulic servo systems in the presence of largely unknown matched and mismatched disturbances is proposed. By employing two extended state observers for each channel of the load dynamics and pressure dynamics of the considered hydraulic system, the large matched and mismatched disturbances are successfully compensated. In addition, a time-varying barrier Lyapunov function (BLF) of asymmetric type has been employed to make sure that the position output is never violated. The resulting controller is synthesized using the backstepping procedure. The stability of the whole closed-loop hydraulic system associated with the dual extended state observer (ESO)-based controller is strictly guaranteed. In theory, the proposed control strategy can not only ensure the output satisfy the preset constrained space, but also enhance the output tracking performance when the system faces various largely unknown disturbances. The effectiveness of the proposed controller has also been demonstrated via comparative simulation results.

scholarly journals Iterative Learning Control with Extended State Observer for Telescope System

2015 ◽  
Vol 2015 ◽  
pp. 1-8 ◽  
Author(s):  
Huaxiang Cai ◽  
Yongmei Huang ◽  
Junfeng Du ◽  
Tao Tang ◽  
Dan Zuo ◽  
...  
Keyword(s):  
Iterative Learning Control ◽  
Control Method ◽  
Tracking Error ◽  
Learning Control ◽  
State Observer ◽  
Iterative Learning ◽  
Extended State Observer ◽  
Extended State ◽  
Nonlinear Disturbances ◽  
Telescope System

An Iterative Learning Control (ILC) method with Extended State Observer (ESO) is proposed to enhance the tracking precision of telescope. Telescope systems usually suffer some uncertain nonlinear disturbances, such as nonlinear friction and unknown disturbances. Thereby, to ensure the tracking precision, the ESO which can estimate system states (including parts of uncertain nonlinear disturbances) is introduced. The nonlinear system is converted to an approximate linear system by making use of the ESO. Besides, to make further improvement on the tracking precision, we make use of the ILC method which can find an ideal control signal by the process of iterative learning. Furthermore, this control method theoretically guarantees a prescribed tracking performance and final tracking accuracy. Finally, a few comparative experimental results show that the proposed control method has excellent performance for reducing the tracking error of telescope system.

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