Automatic Loop Shaping of MIMO Controllers Satisfying Sensitivity Specifications

2005 ◽  
Vol 128 (2) ◽  
pp. 463-471 ◽  
Author(s):  
O. Yaniv
Keyword(s):  
High Frequency ◽  
Damping Factor ◽  
Notch Filters ◽  
Nonminimum Phase ◽  
Loop Shaping ◽  
Pure Delay

An existing automatic loop shaping algorithm for designing SISO controllers is extended to automatic loop shaping of MIMO controllers that is based on the sequential QFT method. The algorithm is efficient and fast and can search for controllers satisfying many types of restrictions, including constraints on each one of the controller’s elements such as hard restrictions on the high-frequency amplitude or damping factor of notch filters. Moreover, the algorithm can be applied to unstructured uncertain plants, be they stable, unstable, or nonminimum phase, including pure delay.

Automatic Loop Shaping of Structured Controllers Satisfying QFT Performance

2004 ◽  
Vol 127 (3) ◽  
pp. 472-477 ◽  
Author(s):  
O. Yaniv ◽  
M. Nagurka
Keyword(s):  
Phase Ii ◽  
High Frequency ◽  
Notch Filter ◽  
Quantitative Feedback Theory ◽  
Design Problems ◽  
Frequency Dependent ◽  
Nonminimum Phase ◽  
Loop Shaping

This paper presents a robust noniterative algorithm for the design of controllers of a given structure satisfying frequency-dependent sensitivity specifications. The method is well suited for automatic loop shaping, particularly in the context of Quantitative Feedback Theory (QFT), and offers several advantages, including (i) it can be applied to unstructured uncertain plants, be they stable, unstable or nonminimum phase, (ii) it can be used to design a satisfactory controller of a given structure for plants which are typically difficult to control, such as highly underdamped plants, and (iii) it is suited for design problems incorporating hard restrictions such as bounds on the high-frequency gain or damping of a notch filter. It is assumed that the designer has some idea of the controller structure appropriate for the loop shaping problem.

Kick Detection Using Downhole Accelerometer Data

2020 ◽  
Vol 142 (8) ◽  
Author(s):  
Robello Samuel
Keyword(s):  
High Frequency ◽  
Damping Ratio ◽  
Energy Operator ◽  
Damping Factor ◽  
Accelerometer Data ◽  
Intrinsic Mode Functions ◽  
Minimum Entropy ◽  
Time Data ◽  
Essential Information ◽  
Vibration Data

Abstract The high-frequency downhole vibration data include a greater amount of hidden information than the low-frequency surface data. This paper proposes the monitoring of high-frequency acceleration data for early kick detection. The trend of accelerator sensor values is monitored, rather than processed. When the gas, fluid, or oil kick occurs, the fluid influx reduces the viscosity of the fluid in annulus, which causes the degradation of the damping factor. The sensor installed on the drillpipe detects the velocity/acceleration change that results in the damping factor change. This approach includes an analytical model to calculate the effect of the damping ratio on the acceleration calculations. The fluid influx and migration in the wellbore strongly affect the damping factor. The paper presents a method of deconvoluting the sensor values that uses a combination of minimum entropy deconvolution and Teager-Kaiser energy operator to remove the noise, unwanted sensor values, and likelihood of false prediction. It is then proposed to calculate instantaneous jerk and jerk intensity at each depth. The trend of the final intrinsic mode functions (IMF) at each depth is continuously monitored to predict the formation influx, if any. A novel concept of monitoring the incremental IMF and IMF energy at each depth is introduced. This technique is shown to reveal a wealth of information and simplifies the process of monitoring and analyzing the vast amount of available data. The methodology developed is applied to extract the essential information from high-frequency vibration data to make real-time data monitoring straightforward, reliable, and fast.

Recovering the Timing of Impulsive Forces From Noisy Vibration Transients

1995 ◽  
Author(s):  
Daniel J. McCarthy ◽  
Richard H. Lyon
Keyword(s):  
Phase Behavior ◽  
Vibration Signal ◽  
Transient Vibration ◽  
Nonminimum Phase ◽  
Impact Forces ◽  
Impulsive Forces ◽  
Exponential Window ◽  
Pure Delay ◽  
Group Delays ◽  
Impulsive Source

Abstract A transient vibration signal can be processed to extract information about impulsive forces within a machine, by removing the effects of dispersion and reverberation. These source waveform signatures, like the timing and strength of valve impact forces within a reciprocating air compressor, can then be used to diagnose machine faults. Stable and causal inverse filters are guaranteed through the use of minimum-phase processing. Unfortunately, the timing of the impulsive source waveform is lost in this manner. A technique to accurately recover the timing is highly desirable. The time of occurrence of the force input can be robustly obtained from the frequency-averaged group delays of the transfer function and vibration response once the nonminimum-phase behavior of the signals, except that due to pure delay, has been removed. This is best done with the allpass components of the signals because, in addition to the nonminimum-phase inherently present in a structure due to reverberation, additional nonminimum-phase zeros can be artificially introduced by data truncation. Since only the phase is of interest, the nonminimum-phase behavior can be removed by electronically damping the signals with exponential windows, effectively de-reverberating them. In some instances the timing of the impulsive source events that we aim to recover will change as faults develop; also, in any machine there will be some normal random variation in the timing of internal events like valve impacts. The correct timing can be determined in the presence of this inherent variability through the use of a sliding exponential window and statistical curve fitting.

scholarly journals Robust Performance Limitations and Design of Controlled Delayed Systems

2004 ◽  
Vol 126 (4) ◽  
pp. 899-904 ◽  
Author(s):  
O. Yaniv ◽  
M. Nagurka
Keyword(s):  
Transfer Function ◽  
Control Design ◽  
Open Loop ◽  
Phase Margin ◽  
Delayed Systems ◽  
Nonminimum Phase ◽  
Loop Transfer Function ◽  
Performance Limitations ◽  
Pure Delay ◽  
Selection Of

This paper presents performance limitations and a control design methodology for nonminimum phase plants of the pure delay type subject to robustness constraints. Of interest is the design of a set of controllers, for which the open-loop transfer function is a proportional-integral (PI) controller plus delay, meeting constraints on the magnitude of the closed-loop transfer function and on the plant gain uncertainty. These two specifications are used to characterize the robustness, and are a recommended alternative to the gain and phase margin constraints. A control design plot is presented which allows for selection of controller parameters including those for the lowest sensitivity controller, and graphically highlights gain and phase margin tradeoffs. The paper discusses limitations of performance of such systems in terms of crossover frequency and sensitivity. In addition, expressions and design plots are provided for a simplified approximate solution.

High-Frequency Properties and Thickness-Dependent Damping Factor of ${\rm FeCo}{\hbox{–}}{\rm SiO}_{2}$ Thin Films

2012 ◽  
Vol 48 (11) ◽  
pp. 3654-3657 ◽  
Author(s):  
Guangduo Lu ◽  
Huaiwu Zhang ◽  
John Q. Xiao ◽  
Xiaoli Tang ◽  
Zhiyong Zhong ◽  
...  
Keyword(s):  
Thin Films ◽  
High Frequency ◽  
Damping Factor ◽  
Frequency Properties

A Hybrid Energy Model for Predicting High Frequency Vibrational Response of Thin Plates Under Heavy Fluid Loading

2013 ◽  
Author(s):  
Xiangjie Kong ◽  
Hualing Chen ◽  
Danhui Zhu ◽  
Wenbo Zhang
Keyword(s):  
Hybrid Model ◽  
Governing Equation ◽  
High Frequency ◽  
Vibrational Energy ◽  
Polar Coordinates ◽  
Damping Factor ◽  
Fluid Loading ◽  
Heavy Fluid ◽  
Linear Superposition ◽  
Reverberant Field

Energy Finite Element Analysis (EFEA) is a method developed for high-frequency structural response prediction in recent years. In this paper, a hybrid model is developed to improve the prediction levels of the current EFEA energy governing equation for the thin plate in contact with heavy fluid. The neglect of the contribution of direct field is the primary prediction source of error in EFEA especially when the damping is significant. In order to fix this issue, both the reverberant field and the contribution of direct field are considered in the derivation. The fluid loading effect is incorporated in the derivation of the governing equation of direct field component in terms of effective mass and total damping factor in polar coordinates. As for the reverberant plane wave component, instead of the driving point, the injected power is modified as the scattered energy arising from direct field located at the boundaries, which is in consistent with the formation mechanism. The overall vibrational energy is the linear superposition of both fields. Numerical simulations on a rectangular plate validate the hybrid model through the comparison with the analytical modal solutions and show that the proposed hybrid model has a more accurate prediction comparing with the classical EFEA results.

Wide-Band Loop Shaping for Modulation of Energy Transmission in Nonminimum-Phase Systems

2018 ◽  
Author(s):  
Tianyu Jiang ◽  
Jiong Tang ◽  
Xu Chen
Keyword(s):  
System Performance ◽  
Closed Loop ◽  
Performance Metrics ◽  
Filter Design ◽  
Wide Band ◽  
Interpolation Theory ◽  
Energy Transmission ◽  
Nonminimum Phase ◽  
Loop Shaping ◽  
Wide Range

Modulating the closed-loop transmission of energy in a wide frequency band without sacrificing overall system performance is a fundamental issue in a wide range of applications from precision control, active noise cancellation, to energy guiding. This paper introduces a loop-shaping approach to create such wideband closed-loop behaviors, with a particular focus on systems with nonminimum-phase zeros. Pioneering an integration of the interpolation theory with a model-based parameterization of the closed loop, the work proposes a filter design that matches the inverse plant dynamics locally and creates a framework to shape energy transmission with user defined performance metrics in the frequency domain. Application to laser-based powder bed fusion additive manufacturing validates the feasibility to compensate wide-band vibrations and to flexibly control system performance at other frequencies.

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