Measurement Errors in Closed-Loop Frequency Response Estimates

1980 ◽  
Vol 102 (1) ◽  
pp. 13-20
Author(s):  
P. W. Davall ◽  
P. N. Nikiforuk
Keyword(s):  
Frequency Response ◽  
Measurement Errors ◽  
Closed Loop ◽  
Power Spectra ◽  
Open Loop ◽  
Feedback Signal ◽  
Single Input Single Output ◽  
Closed Loop Systems ◽  
Single Output ◽  
Single Input

The sampling distributions associated with frequency response estimates of single input, single output closed-loop systems are derived for the case where both the output and feedback signal measurements are subject to added noise. This work is an extension of that done by Goodman [1-3] and Akaike [4, 5] on open-loop systems. Conditions for response estimate bias are investigated and approximate distributions for the power spectra estimates of the added noise terms are derived.

Analytic Loop Shaping Methods in Quantitative Feedback Theory

1994 ◽  
Vol 116 (2) ◽  
pp. 169-177 ◽  
Author(s):  
D. F. Thompson ◽  
O. D. I. Nwokah
Keyword(s):  
Uncertain Systems ◽  
Closed Loop ◽  
Design Method ◽  
Control Design ◽  
Quantitative Feedback Theory ◽  
Single Input Single Output ◽  
Single Output ◽  
Direct Design ◽  
Single Input ◽  
Robust Control Design

Quantitative Feedback Theory (QFT), a robust control design method introduced by Horowitz, has been shown to be useful in many cases of multi-input, multi-output (MIMO) parametrically uncertain systems. Prominent is the capability for direct design to closed-loop frequency response specifications. In this paper, the theory and development of optimization-based algorithms for design of minimum-gain controllers is presented, including an illustrative example. Since MIMO QFT design is reduced to a series of equivalent single-input, single-output (SISO) designs, the emphasis is on the SISO case.

scholarly journals Passivity based Approach for the Level Control of Spherical Tank Process

2020 ◽  
Vol 13 (1) ◽  
Author(s):  
Priya C ◽  
Lakshmi Ponnnusamy
Keyword(s):  
Real Time ◽  
Open Loop ◽  
Level Control ◽  
Time Model ◽  
Single Input Single Output ◽  
The Real ◽  
Single Output ◽  
Spherical Tank ◽  
Tank System ◽  
Single Input

The aim of this paper is to obtain the mathematical model and the real time model of the Single Input Single Output (SISO) conical tank system. The experimental model is obtained from the open loop response in real time and the transfer function is obtained using the two point method. For the real time model, two different controllers namely Zeigler Nichols tuned PI controller and passivity based controller are designed and tested in simulation and the performance of both the controllers are tested for servo operation and regulatory operation. The designed controllers are tested in Simulation and the response is recorded. The simulation results shows that the Passivity based Controller works better for the spherical tank process.

Design of Dual-Range Linear Controllers for Nonlinear Systems

1991 ◽  
Vol 113 (4) ◽  
pp. 590-596 ◽  
Author(s):  
A. Nassirharand
Keyword(s):  
Closed Loop ◽  
Loop Model ◽  
Model Matching ◽  
Matching Problem ◽  
Single Input Single Output ◽  
Stabilizing Controllers ◽  
Closed Loop Systems ◽  
Single Output ◽  
Highly Nonlinear ◽  
Linear Controllers

A new procedure for synthesis of dual-range linear controllers for use with highly nonlinear, deterministic, time-invariant, and single-input single-output systems in a unity feedback configuration is developed. The procedure uses a factorization approach coupled with optimization which is used to parameterize and search the class of all stabilizing controllers for linear systems with integrity. The objective of the synthesis approach is to arrive at robust closed-loop systems that are solutions to the closed-loop model matching problem. The procedure is presented in an algorithmic form, and it is demonstrated via example problems. The results are compared with those previously obtained using a frequency domain approach.

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.

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