Robust Stability with System Uncertainties

Author(s):  
A Whalley ◽  
M Ebrahimi

Multivariable system models in the form of parameterized, impedance, matrix quadratic realizations are considered. System uncertainties in the form of mass-inertia or damping variations are acknowledged. Simple proportional controller models are proposed and the effect of model variations on the stability of the closed-loop system is investigated. Frequency domain methods are employed to predict the relative stability condition of the system. Conventional stability margin measures may be invoked while adjusting the controller design parameter to an appropriate setting.

2012 ◽  
Vol 151 ◽  
pp. 626-631
Author(s):  
Qiang Ma ◽  
Jian Gang Lu ◽  
Qin Min Yang ◽  
Jin Shui Chen ◽  
You Xian Sun

This work proposes a generalized predictive control (GPC) based controller for the temperature of HVAC chilled water supply. In this paper, several models of evaporator are firstly introduced, wherein an identified black-box model is selected for the purpose of controller design. Based on this model, a GPC based controller is employed to obtain a satisfactory performance even with the presence of disturbance. The theoretical results show the stability of the closed-loop system and the performance of this scheme is compared with that of traditional PID controller under simulation environment.


Author(s):  
Nga Thi-Thuy Vu

This paper presents a robust adaptive controller that does not depend on the system parameters for an excavator arm. Firstly, the model of the excavator arm is demonstrated in the Euler-Lagrange form considering with overall excavator system. Next, a robust adaptive controller has been constructed from information of state error. In this paper, the stability of overall system is mathematically proven by using Lyapunov stability theory. Also, the proposed controller is model free then the closed loop system is not affected by disturbances and uncertainties. Finally, the simulation is executed in Matlab/Simulink for both presented scheme and the PD controller under some conditions to ensure that the proposed algorithm given the good performances for all cases.


2010 ◽  
Vol 29-32 ◽  
pp. 1175-1180
Author(s):  
Qing Kun Zhou ◽  
Sheng Jian Bai ◽  
Zhi Yong Zhang

The design of variable structure system inputs which are constrained by saturation is studied. For a LTI system which satisfies some conditions, it is shown that appropriate bounded controllers guarantee the system’s global stability and maximize the sliding mode domain on the switching surfaces. Stability conditions of variable structure systems with constrained inputs are relaxed, and the stability of the closed-loop system is guaranteed by using passivity theory of linear passive systems. Moreover, nonlinear sliding surfaces are discussed for variable structure controller design, and a novel nonlinear switching surface is proposed. Finally, the proposed methods are applied to a 2nd order LTI system to show their usefulness.


Author(s):  
G P Liu ◽  
G R Duan ◽  
S Daley

The design of stable observer-based controllers for robust pole assignment is addressed in this paper. The stability problem of these dynamical controllers is investigated, which is often ignored during the controller design. A design formulation of stable observer controllers is presented using state-feedback pole assignment techniques. Although the design formulation is principally aimed at the design of a stable controller, the mixed sensitive function in the frequency domain is also considered to improve the robustness of the closed-loop system. This ensures that the closed-loop system has good robustness and the controller is stable.


Author(s):  
Jinli Qu ◽  
Ronald N. Miles ◽  
N. Eva Wu

This paper presented an H∞-controller design to achieve active damping for a MEMS microphone system. The parametric uncertainties introduced by linearization process were modeled. The stability and performance of the closed-loop system were analyzed for the uncertain microphone model and both were shown to be robust. The nonlinear simulation further verifies that the controller offers the desired performance.


2018 ◽  
Vol 210 ◽  
pp. 02005
Author(s):  
Leonardo Acho ◽  
Pablo Buenestado

The main objective of this paper is to present a controller design based on the K-means clustering theory. The controller is realized in such way that when the plant output is located outside of the designed clustering set, the controller forces it to be in it. Moreover, and according to our real experiment applied to stabilize an unstable integrator plant, our controller approach design is also robust against un-vanishing perturbations and nonlinearity effects on the overall closed-loop system such as saturation, slew-rate limit, and limit bandwidth frequency operation.


2013 ◽  
Vol 303-306 ◽  
pp. 1167-1170
Author(s):  
Zhi Yi Xu ◽  
Xiang Jun Zhang ◽  
Zhen Liu

The paper proposes a new method based on the Viere theorem to decide the range containing the optimal parameters. The method can accelerate the parameters search speed on the computer and avoid some unnecessary job for PID controller design. It can be acted as a criterion to judge the stability of the closed loop system.


Author(s):  
Bozhidar Rakov ◽  
Georgi Ruzhekov

A modified scheme is proposed for control of MIMO plant using a PID and decoupling matrix. The goal better performance of the closed loop systems and in-creased stability margin. By using a relay experiment an oscillating ultimate frequency is found, when the system is on the verge of instability. Using this estimation one applies a correction, which increases the stability margin of the closed loop system.


2021 ◽  
Vol 26 (1) ◽  
pp. 21
Author(s):  
Ahmad Taher Azar ◽  
Fernando E. Serrano ◽  
Nashwa Ahmad Kamal

In this paper, a loop shaping controller design methodology for single input and a single output (SISO) system is proposed. The theoretical background for this approach is based on complex elliptic functions which allow a flexible design of a SISO controller considering that elliptic functions have a double periodicity. The gain and phase margins of the closed-loop system can be selected appropriately with this new loop shaping design procedure. The loop shaping design methodology consists of implementing suitable filters to obtain a desired frequency response of the closed-loop system by selecting appropriate poles and zeros by the Abel theorem that are fundamental in the theory of the elliptic functions. The elliptic function properties are implemented to facilitate the loop shaping controller design along with their fundamental background and contributions from the complex analysis that are very useful in the automatic control field. Finally, apart from the filter design, a PID controller loop shaping synthesis is proposed implementing a similar design procedure as the first part of this study.


Author(s):  
Yiqi Xu

This paper studies the attitude-tracking control problem of spacecraft considering on-orbit refuelling. A time-varying inertia model is developed for spacecraft on-orbit refuelling, which actually includes two processes: fuel in the transfer pipe and fuel in the tank. Based upon the inertia model, an adaptive attitude-tracking controller is derived to guarantee the stability of the resulted closed-loop system, as well as asymptotic convergence of the attitude-tracking errors, despite performing refuelling operations. Finally, numerical simulations illustrate the effectiveness and performance of the proposed control scheme.


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