scholarly journals Nonlinear Control of Hydrostatic Thrust Bearing Using Multivariable Optimization

Mathematics ◽  
2021 ◽  
Vol 9 (8) ◽  
pp. 903
Author(s):  
Waheed Ur Rehman ◽  
Wakeel Khan ◽  
Nasim Ullah ◽  
M. D. Shahariar Chowdhury ◽  
Kuaanan Techato ◽  
...  
Keyword(s):  
Mathematical Model ◽  
Thrust Bearing ◽  
Nonlinear Modeling ◽  
Research Work ◽  
State Observer ◽  
Extended State Observer ◽  
Control Technique ◽  
Extended State ◽  
Modeling And Control ◽  
Fluid Film Thickness

This research work is focused on the nonlinear modeling and control of a hydrostatic thrust bearing. In the proposed work, a mathematical model is formulated for a hydrostatic thrust bearing system that includes the effects of uncertainties, unmodelled dynamics, and nonlinearities. Depending on the type of inputs, the mathematical model is divided into three subsystems. Each subsystem has the same output, i.e., fluid film thickness with different types of input, i.e., viscosity, supply pressure, and recess pressure. An extended state observer is proposed to estimate the unavailable states. A backstepping control technique is presented to achieve the desired tracking performance and stabilize the closed-loop dynamics. The proposed control technique is based on the Lyapunov stability theorem. Moreover, particle swarm optimization is used to search for the best tuning parameters for the backstepping controller and extended state observer. The effectiveness of the proposed method is verified using numerical simulations.

Extended state observer-based back-stepping control for hypersonic reentry vehicle with input constraints

2018 ◽  
Vol 36 (3) ◽  
pp. 921-947 ◽  
Author(s):  
Chen Chen ◽  
Guangfu Ma ◽  
Yueyong Lyu ◽  
Yanning Guo
Keyword(s):  
State Observer ◽  
Lyapunov Theory ◽  
Extended State Observer ◽  
Control Technique ◽  
Control Input ◽  
Sigmoid Function ◽  
Input Constraints ◽  
Extended State ◽  
Reentry Vehicle ◽  
Back Stepping Control

Abstract This paper investigates the attitude-tracking control problem of hypersonic reentry vehicle in cases of multiple uncertainties, external disturbances and input constraints. The controller design is based on synthesizing the extended state observer (ESO) into a back-stepping control technique. This control-oriented model is formulated with mismatched and matched uncertainties. They reflect the total disturbances that group different types of aerodynamic uncertainties and external moment disturbances. In order to improve the system robustness, a sigmoid function-based ESO is first proposed. This will estimate the total disturbance and is equipped with a controller. The sigmoid smooth function is also introduced for the purpose of handling the input constraints. This will approximate saturation and guarantee that the control input is bounded. Error states between the actual control input and the desired control input are integrated to compensate for the saturation effect. Following this, the stability of the closed-loop system is proved within the Lyapunov theory framework. Several simulations are then investigated to illustrate the effectiveness of the proposed constrained attitude control scheme.

Predictive extended state observer-based robust control for uncertain linear systems with experimental validation

2021 ◽  
pp. 014233122110025
Author(s):  
Sushant N Pawar ◽  
Rajan H Chile ◽  
Balasaheb M Patre
Keyword(s):  
Robust Control ◽  
Process Model ◽  
Real Life ◽  
State Observer ◽  
Higher Order ◽  
Internal Model Control ◽  
Extended State Observer ◽  
Control Technique ◽  
Extended State ◽  
Model Control

This paper describes a predictive extended state observer-based robust control for uncertain process control applications. The technique discussed in the article uses the extended state observer (ESO) that can estimate the dynamics of the system as well as total disturbance encountered in the system. The disturbances, parametric uncertainties associated with the processes are treated as an extended state variable to be estimated in real-time using ESO. With the implementation of a predictive algorithm with an ESO, the proposed control structure extends its applicability to time-delayed higher-order processes. The proposed control technique utilizes the simple first-order modified predictive ESO even in the case of higher-order processes. The novel predictive ESO is able to obtain a delay less estimation of total disturbance as compared with existing normal ESO. Also, novel predictive ESO maintains its stability margin in presence of time delay as well provides better response as compared with normal ESO. Numerical simulations show that the proposed scheme provides a significant improvement in transient response as compared with internal model control-based proportional-integral-derivative (IMC-PID) control. The proposed scheme requires less knowledge of the process as compared with the IMC-PID structure. The implementation of the proposed control is tested on a real-life single tank level control system. Because of its merit, the suggested technique can be used as automatic for online tuning, as it is less reliant on the process model.

Extended State Observer for Sensorless Single Phase Stirling Linear Generator Drives

2013 ◽  
Vol 416-417 ◽  
pp. 572-576 ◽  
Author(s):  
Shou Ming Zhou ◽  
Li Yi Li ◽  
Hai Lin Zhang ◽  
Bao Quan Kou ◽  
Yi Zhang
Keyword(s):  
Mathematical Model ◽  
Normal State ◽  
Single Phase ◽  
State Observer ◽  
Extended State Observer ◽  
Extended State ◽  
Linear Generator ◽  
Simulation And Experiment ◽  
Position Sensorless

The extended state observer (ESO) was applied in the sensorless single phase Stirling linear generator drives in this paper. The structure of the linear generator was introduced and mathematical model was built. To detect the mover position in the condition of position sensorless, the back-EMF ESO was deduced to calculate the position. This strategy was realized in the simulation and experiment. Compared with the normal state observer, in the conditions of noise and imprecision of generator parameters, ESO would improve the robustness of the system.

scholarly journals Fault-tolerant control for a class of n-order systems based on fast terminal sliding mode and extended state observer

2021 ◽  
pp. 002029402110286
Author(s):  
Pu Yang ◽  
Peng Liu ◽  
ChenWan Wen ◽  
Huilin Geng
Keyword(s):  
Fault Tolerant ◽  
Sliding Mode ◽  
Singular Control ◽  
Fault Tolerant Control ◽  
State Observer ◽  
Extended State Observer ◽  
Extended State ◽  
Terminal Sliding Mode ◽  
Fast Terminal Sliding Mode ◽  
Terminal Sliding Surface

This paper focuses on fast terminal sliding mode fault-tolerant control for a class of n-order nonlinear systems. Firstly, when the actuator fault occurs, the extended state observer (ESO) is used to estimate the lumped uncertainty and its derivative of the system, so that the fault boundary is not needed to know. The convergence of ESO is proved theoretically. Secondly, a new type of fast terminal sliding surface is designed to achieve global fast convergence, non-singular control law and chattering reduction, and the Lyapunov stability criterion is used to prove that the system states converge to the origin of the sliding mode surface in finite time, which ensures the stability of the closed-loop system. Finally, the effectiveness and superiority of the proposed algorithm are verified by two simulation experiments of different order systems.

Extended state observer–based output feedback control for spacecraft pose tracking with control input saturation

2021 ◽  
pp. 095441002110177
Author(s):  
Kejie Gong ◽  
Ying Liao ◽  
Yafei Mei
Keyword(s):  
Feedback Control ◽  
Output Feedback ◽  
Finite Time ◽  
Output Feedback Control ◽  
State Observer ◽  
Extended State Observer ◽  
Control Input ◽  
Extended State ◽  
Pose Tracking ◽  
Control Scheme

This article proposed an extended state observer (ESO)–based output feedback control scheme for rigid spacecraft pose tracking without velocity feedback, which accounts for inertial uncertainties, external disturbances, and control input constraints. In this research, the 6-DOF tracking error dynamics is described by the exponential coordinates on SE(3). A novel continuous finite-time ESO is proposed to estimate the velocity information and the compound disturbance, and the estimations are utilized in the control law design. The ESO ensures a finite-time uniform ultimately bounded stability of the observation states, which is proved utilizing the homogeneity method. A non-singular finite-time terminal sliding mode controller based on super-twisting technology is proposed, which would drive spacecraft tracking the desired states. The other two observer-based controllers are also proposed for comparison. The superiorities of the proposed control scheme are demonstrated by theory analyses and numerical simulations.

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