scholarly journals Stabilization of Magnetic Suspension System by Using Only a First-Order Reset Element without a Derivative Element

Actuators ◽  
2019 ◽  
Vol 8 (1) ◽  
pp. 24 ◽  
Author(s):  
Yuji Ishino ◽  
Takeshi Mizuno ◽  
Masaya Takasaki ◽  
Daisuke Yamaguchi
Keyword(s):  
Suspension System ◽  
Magnetic Suspension ◽  
Pass Filter ◽  
Low Pass Filter ◽  
Single Degree Of Freedom ◽  
Transient Characteristics ◽  
First Order ◽  
Single Degree ◽  
Low Pass ◽  
Magnetic Suspension System

The stabilization of a magnetic suspension system is achieved by using a low-pass filter (LPF) with a nonlinear integrator without any other element. A proportional-derivative (PD) control is commonly used as the simplest method of stabilizing a magnetic suspension system. Meanwhile, a first-order reset element (FORE) was applied to improve transient characteristics. The original FORE was a first-order LPF with a nonlinear reset integrator element. A magnetic suspension system cannot be stabilized by a linear LPF, nor the original FORE. In this work, the reset conditions of the FORE were modified for magnetic suspension. This modified FORE succeeded in stabilizing a magnetic suspension system. The efficacy of the modified FORE was demonstrated by simulations and experiments. A single degree of freedom magnetic suspension system was used in the experiment.

A Method for Selecting Velocity Filter Cut-Off Frequency for Maximizing Impedance Width Performance in Haptic Interfaces

2014 ◽  
Vol 137 (2) ◽  
Author(s):  
Vinay Chawda ◽  
Ozkan Celik ◽  
Marcia K. O'Malley
Keyword(s):  
Haptic Interface ◽  
Haptic Interfaces ◽  
Pass Filter ◽  
Low Pass Filter ◽  
Single Degree Of Freedom ◽  
Single Degree ◽  
Simulation Based ◽  
Low Pass ◽  
Position Data ◽  
Velocity Filtering

This paper analyzes the effect of velocity filtering cut-off frequency on the Z-width performance of haptic interfaces. Finite difference method (FDM) cascaded with a low pass filter is the most commonly used technique for estimating velocity from position data in haptic interfaces. So far, there is no prescribed method for obtaining the FDM + filter cut-off frequency that will maximize Z-width performance. We present a simulation based method to demonstrate that there exists such an ideal FDM + filter cut-off frequency, and that it can be predicted by numerical simulation based on an identified model of a haptic interface. Experiments are conducted on a single degree-of-freedom (DOF) linear haptic interface to validate the simulation results.

Disturbance-observer based control of voltage-source-converter under unbalanced voltage conditions

2017 ◽  
Vol 14 (6) ◽  
pp. 522-531 ◽  
Author(s):  
Akhtar Rasool ◽  
Esref Emre Ozsoy ◽  
Fiaz Ahmad ◽  
Asif Sabanoviç ◽  
Sanjeevikumar Padmanaban
Keyword(s):  
Disturbance Observer ◽  
Operating Conditions ◽  
Voltage Source ◽  
Pass Filter ◽  
Low Pass Filter ◽  
Content Type ◽  
Negative Sequence ◽  
First Order ◽  
Unbalanced Voltage ◽  
Low Pass

Purpose This paper aims to propose a novel grid current control strategy for grid-connected voltage source converters (VSCs) under unbalanced grid voltage conditions. Design/methodology/approach A grid voltage dynamic model is represented in symmetrical positive and negative sequence reference frames. A proportional controller structure with a first-order low-pass filter disturbance observer (DOB) is designed for power control in unbalanced voltage conditions. This controller is capable of meeting the positive sequence power requirements, and it also eliminates negative sequence power components which cause double-frequency oscillations on power. The symmetrical components are calculated by using the second-order generalized integrator-based observer, which accurately estimates the symmetrical components. Findings Proportional current controllers are sufficient in this study in a wide range of operating conditions, as DOB accurately estimates and feed-forwards nonlinear terms which may be deteriorated by physical and operating conditions. This is the first reported scheme which estimates the VSC disturbances in terms of symmetrical component decomposition and the DOB concept. Originality/value The proposed method does not require any grid parameter to be known, as it estimates nonlinear terms with a first-order low-pass filter DOB. The proposed control system is implemented on a dSPACE ds1103 digital controller by using a three-phase, three-wire VSC.

A modified Bessel filter for amplitude demodulation of respiratory electromyograms

1998 ◽  
Vol 84 (1) ◽  
pp. 378-388 ◽  
Author(s):  
Ronald S. Platt ◽  
Eric A. Hajduk ◽  
Manuel Hulliger ◽  
Paul A. Easton
Keyword(s):  
High Frequency ◽  
Stop Band ◽  
Pass Band ◽  
Third Order ◽  
Pass Filter ◽  
Low Pass Filter ◽  
Transient Characteristics ◽  
Low Pass ◽  
Seventh Order ◽  
Frequency Components

Platt, Ronald S., Eric A. Hajduk, Manuel Hulliger, and Paul A. Easton. A modified Bessel filter for amplitude demodulation of respiratory electromyograms. J. Appl. Physiol. 84(1): 378–388, 1998.—We studied a device that is commonly used for amplitude demodulation of respiratory muscle electromyograms (EMG). This device contains a rectifier and a low-pass filter called a modified third-order Paynter filter. We characterized this filter and found that it has good transient characteristics that suit its task as an EMG demodulator, but it has poor high-frequency attenuation that passes interfering, higher frequency components to the output waveform. Therefore, we designed and constructed a new filter with transient characteristics that are comparable to those of the modified Paynter filter but with superior high-frequency attenuation. This new filter is a modified seventh-order Bessel filter. We also identified a simple technique to convert an existing modified Paynter filter back to an original Paynter filter. The original Paynter filter has a wider pass band than the modified Paynter filter but superior stop-band attenuation.

A THEOREM ON REPEATED FILTERING

2014 ◽  
Vol 23 (10) ◽  
pp. 1450136
Author(s):  
ANTONIJE DJORDJEVIĆ ◽  
DEJAN TOŠIĆ ◽  
MILICA DJURIĆ-JOVIČIĆ
Keyword(s):  
Group Delay ◽  
Moving Average ◽  
Gaussian Filter ◽  
Pass Filter ◽  
Low Pass Filter ◽  
First Order ◽  
Gaussian Filters ◽  
Low Pass ◽  
Butterworth Filters

Repeatedly passing a signal through a low-pass filter may resemble using a Gaussian or hyper-Gaussian filter. Conditions are established for this resemblance. A theorem on approximation of Gaussian and hyper-Gaussian filters by a cascade of simple filters is established and the corresponding phase and group delay characteristics are analyzed. The theorem and the analysis are exemplified by cascading moving-average filters and the first-order Butterworth filters.

scholarly journals The hemodynamic signal as a first-order low-pass temporal filter: Evidence and implications for neuroimaging studies

2016 ◽  
Author(s):  
Antoine Sauvage ◽  
Guillaume Hubert ◽  
Jonathan Touboul ◽  
Jérôme Ribot
Keyword(s):  
Dynamical Response ◽  
Hemodynamic Response Function ◽  
Hemodynamic Responses ◽  
Pass Filter ◽  
Low Pass Filter ◽  
First Order ◽  
Periodic Stimulation ◽  
Neuroimaging Data ◽  
Low Pass ◽  
Stimulation Paradigm

AbstractNeuronal activation triggers blood flow and hemoglobin deoxygenation. These hemodynamic signals can be recorded through magnetic resonance or optical imaging, and allows inferring neural activity in response to stimuli. These techniques are widely used to uncover functional brain architectures. However, their accuracy suffers from distortions inherent to hemodynamic responses and noise. The analysis of these signals currently relies on models of impulse hemodynamic responses to brief stimuli. Here, in order to infer precise functional architectures, we focused on integrated signals associated to the dynamical response of functional maps. To this end, we recorded orientation and direction maps in cat primary visual cortex and confronted two protocols: the conventional episodic stimulation technique and a continuous, periodic stimulation paradigm. Conventional methods show that the dynamics of activation and deactivation of the functional maps follows a linear first-order differential equation representing a low-pass filter. Comparison with the periodic stimulation methods confirmed this observation: the phase shifts and magnitude attenuations extracted at various frequencies were consistent with a low-pass filter with a 5 s time constant. This dynamics open new avenues in the analysis of neuroimaging data that differs from common methods based on the hemodynamic response function. In particular, we demonstrate that inverting this first-order low-pass filter minimized the distortions of the signal and enabled a much faster and accurate reconstruction of functional maps.

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