Compensation for Input Nonlinearities in Repetitive Control Systems Based on Improved Equivalent-Input-Disturbance Approach

2016 ◽  
Vol 20 (1) ◽  
pp. 146-154 ◽  
Author(s):  
Wenjing Cai ◽  
◽  
Min Wu ◽  
Jinhua She ◽  
Luefeng Chen ◽  
...  
Keyword(s):  
Control Systems ◽  
Prior Information ◽  
Repetitive Control ◽  
Control Law ◽  
Extended State ◽  
Input Disturbance ◽  
Actuator Nonlinearities ◽  
Equivalent Input Disturbance ◽  
Reference Input ◽  
Tracking Period

The equivalent-input-disturbance (EID) approach is used to deal with the problem of tracking period signals for a plant with input actuator nonlinearities in a repetitive control system. First, an EID estimator is constructed by taking the full advantage of an extended state observer (ESO), the design of the ESO is explained. Next, an EID estimate, which represents the synthetic effect of the nonlinearities, is incorporated into a repetitive control law to compensate for the effect caused by the nonlinearities. This method does not require any prior information about the nonlinearities. It guarantees perfect tracking for periodic reference input and satisfactory compensation for input nonlinearities at the same time. Finally, simulation and experimental results show the effectiveness of the method.

Missile longitudinal autopilot design using a generalized extended state observer-based mixed H2/H∞ control method

2019 ◽  
Vol 233 (13) ◽  
pp. 4704-4720 ◽  
Author(s):  
Yi Dong ◽  
Jian Li ◽  
Tong Li ◽  
Jie Wu
Keyword(s):  
State Feedback ◽  
State Observer ◽  
The State ◽  
Feedback Controller ◽  
Extended State Observer ◽  
Linear Matrix ◽  
Extended State ◽  
State Feedback Controller ◽  
Input Disturbance ◽  
Equivalent Input Disturbance

This work presents a novel robust control design approach for missile longitudinal autopilot under multiple disturbances and uncertainties. The uncertainties and disturbances of the missile dynamics are treated as a lumped disturbance based on the concept of equivalent input disturbance. Then a generalized extended state observer is employed to estimate the system states and the equivalent input disturbance in an integrated manner. These estimates are used to construct the state-feedback controller as well as to attenuate the effect of the exogenous disturbances and endogenous uncertainties. The state-feedback controller is obtained by solving the linear matrix inequalities of mixed [Formula: see text]/[Formula: see text] control problem, which provides an impressive flexibility to tune the controller to compromise between [Formula: see text] performance and [Formula: see text] performance. Closed-loop stability of the system under the presented controller-observer structure is also established. The proposed design tactfully circumvents the engineering implementation problems encountered by mixed [Formula: see text]/[Formula: see text] control, achieves strong robustness against disturbances and uncertainties, and does not involve any complicated nonlinear control methodologies. Numerical simulation results of nominal and perturbed performance comparisons with classic methods sufficiently demonstrate the feasibility and robustness of the proposed method.

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