FEEDFORWARD TRACKING CONTROL BASED ON LIMITED FREQUENCY RESPONSE SERIES MODEL

2001 ◽  
Vol 37 (08) ◽  
pp. 43 ◽  
Author(s):  
Cheng Ma
Keyword(s):  
Frequency Response ◽  
Tracking Control ◽  
Limited Frequency

scholarly journals Overvoltages and Transients Identification In On-line Bushing Monitoring

2020 ◽  
Vol 69 (3) ◽  
Author(s):  
Wieslaw Gil ◽  
Wiktor Masłowski ◽  
Przemysław Wronek
Keyword(s):  
Frequency Response ◽  
Support Service ◽  
Monitoring Systems ◽  
Resonance Phenomena ◽  
Limited Frequency ◽  
On Line ◽  
High Dynamics

Overvoltages and transients are sometimes recognized as the cause of bushings’ rapid failure. This fact is confirmed by the studies published at the 2018 CIGRE session. They can also initiate dangerous resonance phenomena in transformer windings. The identification of very fast overvoltages characterized by high dynamics of voltage changes, so-called "transients", is difficult due to the limited frequency response of station voltage transformers. However, the bushing monitoring systems, based on the so-called "voltage method" can be used for this purpose successfully. There are several running bushing monitoring systems based on this method in Poland. The transients’ events are registered together with their oscillographs in Transformer Monitoring Systems (TMS). The overvoltage statistics are also performed to support service procedures.The TMS are integrated with station systems, which greatly increases the possibility of overvoltages phenomena analyzing.

Real Time Estimation of Elastic Deformation for End-Point Tracking Control of Flexible Two-Link Manipulators

1993 ◽  
Vol 115 (3) ◽  
pp. 385-393 ◽  
Author(s):  
Jack Zhijie Xia ◽  
Chia-Hsiang Menq
Keyword(s):  
Frequency Response ◽  
Elastic Deformation ◽  
Digital Filter ◽  
Tracking Control ◽  
Response Ratio ◽  
End Point ◽  
Point Tracking ◽  
Point Motion ◽  
Stable Subsystem ◽  
Unstable Subsystem

In this paper, an elastic-deformation estimator is proposed for real time end-point tracking control of a flexible two-link manipulator. Due to the noncolocated characteristics of the system, the inverse model (from end-point motion to control torques) is divided into two subsystems, namely, the stable subsystem and the unstable one, corresponding to the causal part and noncausal part of the system’s elastic motion, respectively. A digital filter is formulated to replace the unstable subsystem so as to estimate the noncausal part of the elastic motion associated with a specified end-point motion. For the design of the filter, the frequency response ratio between the filter and the unstable subsystem is used as the criterion, the objective of which is to have the frequency response ratio have zero phase shift as well as unity gain within a specified frequency range. It is shown that due to the noncausal characteristics of the unstable subsystem, preview information of the input trajectory is required for implementing the proposed filter, and the estimation accuracy increases as increasing the preview steps. Based on the stable subsystem and the proposed digital filter, a time-varying estimator is designed to estimate the elastic motion of the system when the end-point motion is specified. A command feedforward controller is then used to calculate the required control torques based on the estimated elastic deformation and the desired end-point motion. The computed torques along with a feedback controller then form a control scheme making the flexible two-link manipulator become capable of precision end-point tracking. Simulation results are presented to show the performance of the proposed end-point tracking scheme as well as the elastic-deformation estimator.

An Alternative Approach to Substructuring in Vibratory Systems Containing Soft Rubber Isolators

2019 ◽  
Vol 141 (6) ◽  
Author(s):  
Viviane Cassol Marques ◽  
Michael John Brennan
Keyword(s):  
Frequency Response ◽  
Complete System ◽  
Finite Element Models ◽  
Frequency Range ◽  
Vibratory Response ◽  
Alternative Approach ◽  
Speed Up ◽  
Limited Frequency ◽  
Rubber Isolator ◽  
Soft Rubber

Abstract Built-up structures, such as airplanes, ships, and even refrigeration systems, which have many components, can be substructured to speed up and facilitate the process of calculating the vibratory response of the complete system. In many structures, there are rubber isolators that connect component parts, and these connections can each occur over a finite distributed area. It is often convenient and intuitive to substructure the system at the isolators. However, in previous work, it has been shown that the frequency response of the complete system does not always agree with the frequency response of the system calculated from the mobilities of the subsystems. It was thought that this was due to the distributed area connection of the isolators, and this motivated the study reported in this article. An investigation into some issues that occur when substructuring a system that contains soft distributed isolators is described. Using finite element models, it is shown that if a system is substructured, such that the interface between the substructures occurs at a soft rubber isolator, then there is a limited frequency range over which the frequency response function of the assembled system is accurate. It is further shown that it is far better to substructure the system, at stiff, discrete connections, if possible. The frequency range over which the frequency response of the assembled system should then be more accurate over a much wider frequency range.

scholarly journals Acousto-Optic Comb Interrogation System for Random Fiber Grating Sensors with Sub-nm Resolution

Sensors ◽  
2021 ◽  
Vol 21 (12) ◽  
pp. 3967
Author(s):  
Dragos A. Poiana ◽  
Jose A. Garcia-Souto ◽  
Xiaoyi Bao
Keyword(s):  
Frequency Response ◽  
Acoustic Waves ◽  
Frequency Comb ◽  
Surface Acoustic Waves ◽  
Fiber Grating ◽  
Phase Detection ◽  
Limited Frequency ◽  
Small Cracks ◽  
Non Destructive

The broad-frequency response and nanometer-range displacements of ultrasound detection are essential for the characterization of small cracks, structural health monitoring and non-destructive evaluation. Those perturbations are generated at sub-nano-strain to nano-strain levels. This corresponds to the sub-nm level and, therefore, to about 0.1% of wavelength change at 1550 nm, making it difficult to detect them by conventional interferometric techniques. In this paper, we propose a demodulation system to read the random fiber grating spectrum using a self-heterodyne acousto-optic frequency comb. The system uses a self-heterodyne approach to extract phase and amplitude modulated signals to detect surface acoustic waves with sub-nanometer amplitudes in the frequency domain. The method can detect acoustic frequencies of 1 MHz and the associated displacement. The system is calibrated via phase detection with a heterodyne interferometer, which has a limited frequency response of up to 200 kHz. The goal is to achieve sub-nanometer strain detection at MHz frequency with random fiber gratings.

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