scholarly journals Parametric Robust Control of the Multivariable 2 × 2 Looper System in Steel Hot Rolling: A Comparison between Multivariable QFT and H∞

Metals ◽  
2019 ◽  
Vol 9 (8) ◽  
pp. 839 ◽  
Author(s):  
Luis F. Cantú ◽  
Pedro Mendiola ◽  
Álvaro A. Domínguez ◽  
Alberto Cavazos
Keyword(s):  
Frequency Domain ◽  
Hot Rolling ◽  
Performance Indicators ◽  
Single Input Single Output ◽  
Single Output ◽  
Stability Robustness ◽  
Higher Power ◽  
Single Input ◽  
Hot Rolling Mill ◽  
Looper System

Two robust mutlivariable controllers, H∞ and a decentralized quantitative feedback theory (QFT), are designed in the frequency domain for the 2 × 2 looper system in a steel hot rolling mill to keep stability in the presence of parametric uncertainties. The H∞ controller is designed by using the mixed sensitivity approach, while the multivariable decentralized QFT is designed by the extension of the sequential loop closing method presented elsewhere. Stability robustness conditions are verified in the frequency domain, while simulations in time domain are carried out to evaluate the controllers and compare their performance along with that of proportional + integral (PI) and single input single output (SISO) QFT controllers designed earlier. The QFT controller shows the best balance among the performance indicators analyzed here; however, at the expenses of using higher power in one of the control inputs.

Multivariable Loop-Shaping in Bilateral Telemanipulation

2005 ◽  
Vol 128 (3) ◽  
pp. 482-488 ◽  
Author(s):  
Kevin B. Fite ◽  
Michael Goldfarb
Keyword(s):  
Impedance Control ◽  
Singular Values ◽  
Single Input Single Output ◽  
Single Output ◽  
Stability Robustness ◽  
Loop Shaping ◽  
Single Input ◽  
The Stability ◽  
Three Degree Of Freedom ◽  
And Control

This paper presents an architecture and control methodology for obtaining transparency and stability robustness in a multivariable bilateral teleoperator system. The work presented here extends a previously published single-input, single-output approach to accommodate multivariable systems. The extension entails the use of impedance control techniques, which are introduced to render linear the otherwise nonlinear dynamics of the master and slave manipulators, in addition to a diagonalization multivariable loop shaping technique, used to render tractable the multivariable compensator design. A multivariable measure of transparency is proposed based on the relative singular values of the environment and transmitted impedance matrices. The approach is experimentally demonstrated on a three degree-of-freedom scaled telemanipulator pair with a highly coupled environment. Using direct measurement of the power delivered to the operator to assess the system’s stability robustness, along with the proposed measure of multivariable transparency, the loop-shaping compensation is shown to improve the stability robustness by a factor of two and the transparency by more than a factor of five.

Robust Control of Active Suspensions

2007 ◽  
Author(s):  
Dongsuk Kum ◽  
Huei Peng
Keyword(s):  
Degrees Of Freedom ◽  
Disturbance Attenuation ◽  
Control Synthesis ◽  
Control Architecture ◽  
Single Input Single Output ◽  
Single Output ◽  
Stability Robustness ◽  
Road Disturbance ◽  
Main Culprit ◽  
Single Input

Active suspension has been widely studied in recent decades but the implementation of the single-input, single-output (SISO) force-control architecture that many of the prior studies use has had limited success due to the lightly damped zeros. The inherent trade-off between robust stability and road disturbance attenuation for SISO control architecture is the main culprit. In this paper, we study whether the single-input, two-output (SITO) control architecture provides sufficient degrees of freedom in the control synthesis. First, a quarter car model with an electromagnetic motor is derived and the improved LQG/LTR design technique is employed to simultaneously recover both stability robustness and disturbance attenuation properties at the expense of measurement noise sensitivity. It was found that if the control system is restricted to SISO architecture, sprung mass acceleration is the most promising choice among practical measurements. Both classical and modern control approaches are used to analyze the effectiveness of the proposed method and its closed-loop performance. Simulation results show that stability robustness and disturbance attenuation can be dramatically improved by the SITO architecture over its SISO counterpart.

scholarly journals Iterative Method for Tuning Multiloop PID Controllers Based on Single Loop Robustness Specifications in the Frequency Domain

Processes ◽  
2021 ◽  
Vol 9 (1) ◽  
pp. 140
Author(s):  
Juan Garrido ◽  
Mario L. Ruz ◽  
Fernando Morilla ◽  
Francisco Vázquez
Keyword(s):  
Frequency Domain ◽  
Open Loop ◽  
The Other ◽  
Pid Controllers ◽  
Single Input Single Output ◽  
Tuning Method ◽  
Pid Tuning ◽  
Single Output ◽  
Gain Margin ◽  
Single Input

Multiloop proportional-integral-derivative (PID) controllers are widely used for controlling multivariable processes due to their understandability, simplicity and other practical advantages. The main difficulty of the methodologies using this approach is the fact that the controllers of different loops interact each other. Thus, the knowledge of the controllers in the other loops is necessary for the evaluation of one loop. This work proposes an iterative design methodology of multiloop PID controllers for stable multivariable systems. The controllers in each step are tuned using single-input single-output (SISO) methods for the corresponding effective open loop process (EOP), which considers the interaction of the other loops closed with the controllers of the previous step. The methodology uses a frequency response matrix representation of the system to avoid process approximations in the case of elements with time delays or complicated EOPs. Consequently, different robustness margins on the frequency domain are proposed as specifications: phase margin, gain margin, phase and gain margin combination, sensitivity margin and linear margin. For each case, a PID tuning method is described and detailed for the iterative methodology. The proposals are exemplified with two simulations systems where the obtained performance is similar or better than that achieved by other authors.

Frequency Domain Stability Criterion for Vibration Control of the Bernoulli-Euler Beam

1988 ◽  
Vol 110 (3) ◽  
pp. 303-307 ◽  
Author(s):  
Yossi Chait ◽  
Clark J. Radcliffe ◽  
C. R. MacCluer
Keyword(s):  
Frequency Domain ◽  
Stability Criterion ◽  
Nyquist Plot ◽  
Distributed Parameter ◽  
Output Frequency ◽  
Euler Beam ◽  
Single Input Single Output ◽  
Single Output ◽  
Single Input ◽  
Domain Stability

A new single-input single-output frequency domain stability criterion for distributed parameter systems is illustrated by application to feedback control of a Bernoulli-Euler beam. The system is modeled using an infinite partial fraction expansion, while the control design is based on a truncated model. The Nyquist plot is shown to lie within a “tube of uncertainty” of the plot for the truncated model. Several numerical examples illustrate the power and simplicity of this criterion.

Robust polynomial eigenstructure assignment using dynamic feedback controllers

1997 ◽  
Vol 211 (1) ◽  
pp. 35-51 ◽  
Author(s):  
B A White
Keyword(s):  
Eigenstructure Assignment ◽  
Systematic Design ◽  
Dynamic Feedback ◽  
Feedback Controllers ◽  
Single Input Single Output ◽  
Single Output ◽  
Stability Robustness ◽  
Single Input ◽  
And Performance ◽  
Value Decomposition

This paper presents a dynamic controller format for use in polynomial eigenstructure assignment. It formulates the controller in singular-value decomposition format, which enables the designer to use simple SISO (single-input, single-output) compensators, together with direction matrices to construct the controller. The technique utilizes the root locus to evaluate stability and performance. It also introduces several metrics for decoupling, disturbance rejection, actuator movement and stability robustness in a graphical manner that allows a systematic design to be carried out. The paper also includes a two-input, two-output design example to illustrate the technique.

Comparative analysis of SISO and wavelength diversity-based FSO systems at different transmitter power levels

2020 ◽  
Vol 0 (0) ◽  
Author(s):  
Varun Srivastava ◽  
Abhilash Mandloi ◽  
Dhiraj Kumar Patel
Keyword(s):  
Optical Signal ◽  
Free Space Optical ◽  
Optical Source ◽  
Transmit Power ◽  
Single Input Single Output ◽  
Transmitter Power ◽  
Single Output ◽  
Communication Links ◽  
Single Input ◽  
Matching Performance

AbstractFree space optical (FSO) communication refers to a line of sight technology, which comprises optical source and detector to create a link without the use of physical connections. Similar to other wireless communication links, these are severely affected by losses that emerged due to atmospheric turbulence and lead to deteriorated intensity of the optical signal at the receiver. This impairment can be compensated easily by enhancing the transmitter power. However, increasing the transmitter power has some limitations as per radiation regulations. The requirement of high transmit power can be reduced by employing diversity methods. This paper presents, a wavelength-based diversity method with equal gain combining receiver, an effective technique to provide matching performance to single input single output at a comparatively low transmit power.

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