Control of Uncertain Nonlinear Systems Using an Uncertainty and Disturbance Estimator

2011 ◽  
Vol 134 (2) ◽  
Author(s):  
V. S. Deshpande ◽  
S. B. Phadke
Keyword(s):  
Nonlinear Systems ◽  
Linear Systems ◽  
Uncertain Nonlinear Systems ◽  
Initial Control ◽  
Uncertainty And Disturbance Estimator ◽  
The Stability ◽  
Uncertain Linear Systems ◽  
Disturbance Estimator

In this paper, we extend a recently developed method (Zhong and Rees, 2004, “Control of Uncertain LTI Systems Based on an Uncertainty and Disturbance Estimator,” ASME J. Dyn. Syst., Meas., Control, 126(4), pp. 905–910), for controlling uncertain linear systems using an uncertainty and disturbance estimator, to uncertain nonlinear systems. Further the control proposed in this paper removes the drawback of large initial control underlying the method. The stability of the overall system of the plant and the estimator is proved. The efficacy of the method is illustrated by simulation.

scholarly journals Sliding mode learning control of uncertain nonlinear systems with Lyapunov stability analysis

2018 ◽  
Vol 41 (6) ◽  
pp. 1750-1760
Author(s):  
Erkan Kayacan
Keyword(s):  
Stability Analysis ◽  
Nonlinear Systems ◽  
Lyapunov Stability ◽  
Sliding Mode ◽  
Learning Control ◽  
System Stability ◽  
Uncertain Nonlinear Systems ◽  
System Behaviour ◽  
Lyapunov Stability Analysis ◽  
The Stability

This paper addresses the Sliding Mode Learning Control (SMLC) of uncertain nonlinear systems with Lyapunov stability analysis. In the control scheme, a conventional control term is used to provide the system stability in compact space while a type-2 neuro-fuzzy controller (T2NFC) learns system behaviour so that the T2NFC completely takes over overall control of the system in a very short time period. The stability of the sliding mode learning algorithm has been proven in the literature; however, it is restrictive for systems without overall system stability. To address this shortcoming, a novel control structure with a novel sliding surface is proposed in this paper, and the stability of the overall system is proven for nth-order uncertain nonlinear systems. To investigate the capability and effectiveness of the proposed learning and control algorithms, the simulation studies have been carried out under noisy conditions. The simulation results confirm that the developed SMLC algorithm can learn the system behaviour in the absence of any mathematical model knowledge and exhibit robust control performance against external disturbances.

EWSE and Uncertainty and Disturbance Estimator Based Pitch Angle Control for Wind Turbine Systems Operating in Above-Rated Wind Speed Region

2019 ◽  
Vol 142 (3) ◽  
Author(s):  
Xuguo Jiao ◽  
Qinmin Yang ◽  
Bo Fan ◽  
Qi Chen ◽  
Yong Sun ◽  
...  
Keyword(s):  
Wind Speed ◽  
Wind Turbine ◽  
Pitch Angle ◽  
Support Vector ◽  
Control Scheme ◽  
High System ◽  
Uncertainty And Disturbance Estimator ◽  
Systematic Solution ◽  
The Stability ◽  
Disturbance Estimator

Abstract As wind energy becomes a larger part of the world's energy portfolio, the control of wind turbines is still confronted with challenges including wind speed randomness and high system uncertainties. In this study, a novel pitch angle controller based on effective wind speed estimation (EWSE) and uncertainty and disturbance estimator (UDE) is proposed for wind turbine systems (WTS) operating in above-rated wind speed region. The controller task is to maintain the WTS's generator power and rotor speed at their prescribed references, without measuring the wind speed information and accurate system model. This attempt also aims to bring a systematic solution to deal with different system characteristics over wide working range, including extreme and dynamic environmental conditions. First, support vector machine (SVR) based EWSE model is developed to estimate the effective wind speed in an online manner. Second, by integrating an UDE and EWSE model into the controller, highly turbulent and unpredictable dynamics introduced by wind speed and internal uncertainties is compensated. Rigid theoretical analysis guarantees the stability of the overall system. Finally, the performance of the novel pitch control scheme is testified via the professional Garrad Hassan (GH) bladed simulation platform with various working scenarios. The results reveal that the proposed approach achieves better performance in contrast to traditional L1 adaptive and proportional-integral (PI) pitch angle controllers.

Uncertainty and Disturbance Estimator-Based Backstepping Control for Nonlinear Systems With Mismatched Uncertainties and Disturbances

2018 ◽  
Vol 140 (12) ◽  
Author(s):  
Jiguo Dai ◽  
Beibei Ren ◽  
Qing-Chang Zhong
Keyword(s):  
Nonlinear Systems ◽  
Reference Model ◽  
Experimental Studies ◽  
Feedback Form ◽  
Backstepping Approach ◽  
Mismatched Uncertainties ◽  
Uncertainty And Disturbance Estimator ◽  
Uniformly Ultimate Boundedness ◽  
System Errors ◽  
Disturbance Estimator

This paper proposes an uncertainty and disturbance estimator (UDE)-based controller for nonlinear systems with mismatched uncertainties and disturbances, integrating the UDE-based control and the conventional backstepping scheme. The adoption of the backstepping scheme helps to relax the structural constraint of the UDE-based control. Moreover, the reference model design in the UDE-based control offers a solution to address the “complexity explosion” problem of the backstepping approach. Furthermore, the strict-feedback form condition in the conventional backstepping approach is also relaxed by using the UDE-based control to estimate and compensate “disturbance-like” terms including nonstrict-feedback terms and intermediate system errors. The uniformly ultimate boundedness of the closed-loop system is analyzed. Both numerical and experimental studies are provided.

Uncertainty and Disturbance Estimator–Based Control for Uncertain LTI-SISO Systems With State Delays

2011 ◽  
Vol 133 (2) ◽  
Author(s):  
R. K. Stobart ◽  
Alon Kuperman ◽  
Qing-Chang Zhong
Keyword(s):  
Control Strategy ◽  
Linear Time ◽  
Single Input Single Output ◽  
Linear Time Invariant ◽  
Single Output ◽  
State Delays ◽  
Uncertainty And Disturbance Estimator ◽  
The Stability ◽  
Siso Systems ◽  
Disturbance Estimator

In this paper, a robust control strategy based on the uncertainty and disturbance estimator (UDE) is proposed for uncertain Linear Time Invariant-Single Input Single Output (LTI-SISO) systems with state delays. The knowledge of the bounds of uncertainties and disturbances is not needed during the design process although it is required for the stability analysis. Both the cases with known and unknown delays are considered. In the case of unknown delays, the terms involving the delays are treated as additional disturbances to the system. The robust stability of the closed-loop system is analyzed in detail, and a stability condition is proposed. Simulations are given to demonstrate the excellent tracking and disturbance rejection capabilities of the UDE-based control strategy.

Event-triggered Neural Network-Based Adaptive Control for a Class of Uncertain Nonlinear Systems

2021 ◽  
pp. 2150275
Author(s):  
Hui Hu ◽  
Yang Li ◽  
Wei Yi ◽  
Yuebiao Wang ◽  
Fan Qu ◽  
...  
Keyword(s):  
Neural Network ◽  
Adaptive Control ◽  
Nonlinear Systems ◽  
Control Method ◽  
Uncertain Nonlinear Systems ◽  
Network Resource ◽  
Lyapunov Approach ◽  
Stability Method ◽  
The Stability ◽  
Event Triggered

In the paper, an event triggering adaptive control method based on neural network (NN) is proposed for a class of uncertain nonlinear systems with external disturbances. In order to reduce the network resource utilization, a novel event-triggered condition by the Lyapunov approach is proposed. In addition, the NN controller and adaptive parameters determined by the Lyapunov stability method are updated only at triggered instants to reduce the amount of calculation. Only one NN is used as the controller in the entire system. The stability analysis results of the closed-loop system are obtained by the Lyapunov approach, which shows that all the signals in the systems with bounded disturbance are semi-globally bounded. Zeno behavior is avoided. Finally, the analytical design is confirmed by the simulation results on a two-link robotic manipulator.

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