scholarly journals ZERO PHASE ERROR FILTERING METHOD BASED ON DIFFUSION EQUATION

2019 ◽  
Author(s):  
Lianyou Lai ◽  
◽  
Weijian Xu ◽  
Keyword(s):  
Diffusion Equation ◽  
Phase Error ◽  
Filtering Method ◽  
Zero Phase ◽  
Error Filtering

Tracking Control of Non-Minimum Phase Systems Using Filtered Basis Functions: A NURBS-Based Approach

2015 ◽  
Author(s):  
Molong Duan ◽  
Keval S. Ramani ◽  
Chinedum E. Okwudire
Keyword(s):  
Tracking Control ◽  
Phase Error ◽  
Approximate Model ◽  
Basis Functions ◽  
Minimum Phase ◽  
Tracking Errors ◽  
Model Inversion ◽  
B Spline ◽  
Phase Systems ◽  
Zero Phase

This paper proposes an approach for minimizing tracking errors in systems with non-minimum phase (NMP) zeros by using filtered basis functions. The output of the tracking controller is represented as a linear combination of basis functions having unknown coefficients. The basis functions are forward filtered using the dynamics of the NMP system and their coefficients selected to minimize the errors in tracking a given trajectory. The control designer is free to choose any suitable set of basis functions but, in this paper, a set of basis functions derived from the widely-used non uniform rational B-spline (NURBS) curve is employed. Analyses and illustrative examples are presented to demonstrate the effectiveness of the proposed approach in comparison to popular approximate model inversion methods like zero phase error tracking control.

Adaptive Zero-Phase Error-Tracking Controllers with Advance Learning

2004 ◽  
Vol 32 (2) ◽  
Author(s):  
M.M. Mustafa ◽  
N.R. Yaacob ◽  
N.A. Nik Mohamed
Keyword(s):  
Phase Error ◽  
Tracking Controllers ◽  
Zero Phase

scholarly journals Fringe Phase-Shifting Field Based Fuzzy Quotient Space-Oriented Partial Differential Equations Filtering Method for Gaussian Noise-Induced Phase Error

Sensors ◽  
2019 ◽  
Vol 19 (23) ◽  
pp. 5202 ◽  
Author(s):  
Yu ◽  
Ji ◽  
Xue ◽  
Wang
Keyword(s):  
Partial Differential Equations ◽  
Differential Equations ◽  
Gaussian Noise ◽  
Quotient Space ◽  
Signal To Noise Ratio ◽  
Phase Error ◽  
Phase Shifting ◽  
Signal To Noise ◽  
Partial Differential ◽  
Filtering Method

Traditional filtering methods only focused on improving the peak signal-to-noise ratio of the single fringe pattern, which ignore the filtering effect on phase extraction. Fringe phase-shifting field based fuzzy quotient space-oriented partial differential equations filtering method is proposed to reduce the phase error caused by Gaussian noise while filtering. First, the phase error distribution that is caused by Gaussian noise is analyzed. Furthermore, by introducing the fringe phase-shifting field and the theory of fuzzy quotient space, the modified filtering direction can be adaptively obtained, which transforms the traditional single image filtering into multi-image filtering. Finally, the improved fourth-order oriented partial differential equations with fidelity item filtering method is established. Experiments demonstrated that the proposed method achieves a higher signal-to-noise ratio and lower phase error caused by noise, while also retaining more edge details.

Phase Correction of Vibrational Circular Dichroic Features

1988 ◽  
Vol 42 (2) ◽  
pp. 336-341 ◽  
Author(s):  
Colleen A. McCoy ◽  
James A. De Haseth
Keyword(s):  
Phase Error ◽  
Absorption Spectrometry ◽  
Phase Correction ◽  
Phase Curve ◽  
Phase Retardation ◽  
Normal Absorption ◽  
Ft Ir ◽  
Arctangent Function ◽  
Circular Dichroic ◽  
Zero Phase

Several sources of phase-correction-induced spectral anomalies in FT-IR vibrational circular dichroism (VCD) spectra have been investigated. Misidentification of the zero-phase retardation position in dichroic interferograms that exhibit no optical or electronic bias can produce spectral errors. Production of such errors is from the introduction of linear phase error into the phase curve. When the zero-phase retardation position is correctly identified, other spectral anomalies, such as “reflected peaks,” can appear in VCD spectra. These peaks are readily observed in quarterwave plate reference spectra. The anomalies are directly correlated to the arctangent function used to define the phase curve and result only from the nature of the VCD signal. VCD spectra can exhibit negative, as well as positive, peaks; consequently the phase correction must be designed to accommodate negative features. Both Mertz and Forman phase-correction algorithms have been modified to correct the phase of VCD interferograms without error. Such corrections are not necessary, or even desirable, for normal absorption spectrometry.

Precision motion control of permanent magnet linear synchronous motor servo system based on an integrated controller with inertia variation compensation

2012 ◽  
Vol 227 (7) ◽  
pp. 1481-1494 ◽  
Author(s):  
Zhijun Li ◽  
Chengying Liu ◽  
Fanwei Meng ◽  
Kai Zhou
Keyword(s):  
Permanent Magnet ◽  
Motion Control ◽  
Disturbance Observer ◽  
Phase Error ◽  
Servo System ◽  
Tracking Performance ◽  
Tracking Controller ◽  
Integrated Controller ◽  
Feed Forward Controller ◽  
Zero Phase

To achieve high robustness and precise motion control of permanent magnet linear synchronous motor servo system, an integrated controller is presented, including a velocity feed forward controller, a zero phase error tracking controller, a disturbance observer and inertia variation compensator. The velocity feed forward controller and the zero phase error tracking controller are included to improve tracking performance and the disturbance observer is involved to enhance disturbance rejection. However, both the zero phase error tracking controller and the disturbance observer are sensitive to inertia variation which often occurs in servo systems. So, an inertia compensator, which consists of a perfect tracking controller for the current loop and a compensation gain, is proposed to retain tracking performance. Detailed experiments are conducted on a PMLSM servo system to confirm the effectiveness of the integrated controller.

Concurrent Design of Continuous Zero Phase Error Tracking Controller and Sinusoidal Trajectory for Improved Tracking Control

1998 ◽  
Vol 123 (1) ◽  
pp. 127-129 ◽  
Author(s):  
Hyung-Soon Park ◽  
Pyung Hun Chang ◽  
Doo Yong Lee
Keyword(s):  
Continuous Time ◽  
Phase Error ◽  
Phase System ◽  
Pass Filter ◽  
Nonminimum Phase ◽  
Tracking Controller ◽  
Feedforward Controller ◽  
Gain Errors ◽  
High Pass ◽  
Zero Phase

A trajectory control strategy for a nonminimum phase system is proposed. A continuous-time version of the Zero Phase Error Tracking Controller (ZPETC), which is a well-known discrete-time feedforward controller, is considered. In the continuous-time case, the overall transfer function consisting of the ZPETC and the closed-loop plant exhibits high-pass filter characteristics. This introduces serious gain errors between the desired and actual output if the desired output is made directly as the ZPETC’s input. This paper proposes the use of a specially designed sinusoidal trajectory to compensate for the gain errors. The sinusoidal trajectory imparts a synergic effect to tracking performance when combined with the continuous ZPETC. Continuous ZPETC with sinusoidal trajectory is evaluated successfully by applying to a nonminimum phase plant, single link flexible arm.

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