Cohen’s Class Time-Frequency Distributions for Measurement Signals as a Means of Monitoring Technological Processes

Fedosenkov, D. B.; Simikova, A. A.; Kulakov, S. M.; Fedosenkov, B. A.

doi:10.3103/s0967091219040065

Cited by 5 publications

(6 citation statements)

References 11 publications

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“…They are based on algorithms for projecting trajectory signals with a time-dependent frequency (chirp signals) [1,4] onto a set of wavelet functions as part of a wavelet thesaurus (wavelet dictionary) [5], wavelet matching pursuit procedures [4,5], and representing the scalar signals in a specific multidimensional medium of Cohen's class time-frequency distributions. [4,6,[7][8][9][10].…”

Section: Research Results Analysismentioning

confidence: 99%

The wavelet transforms technique in the computer-aided system for controlling the quarry unmanned vehicles

et al. 2021

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Introduction. Purpose of the work. Within the framework of the computer-aided system, a technology has been formed for the method of controlling the current trajectories (CTs) of unmanned vehicles (UMVs) when they move along routes in a quarry in open pit mining. The purpose of the presented studies is to analyze the application of a wavelet transforms technique to the problem of routing unmanned vehicles when they move along routes within open pit roads. Methodology. The results of modeling certain one-dimensional signals corresponding to the UMV current trajectories when they deviate to the left / right from a nominal axial trajectory (NAT), as well as their time-frequency representations in a wavelet medium are presented. An algorithm of the procedure for displaying scalar UMV CT control signals in a complex medium of time-frequency wavelet transforms has been developed and described. Such a transformation allows for a functionally transparent and information-capacious monitoring of the UMV movement and efficiently manage the processes of trajectory routing dump trucks in an open pit. Research results, analysis. The processes of modifying the UMV movement current trajectories under the control of the computer-aided system are generated using wavelet transforms methods. They are based on algorithms for projecting the trajectory signals with a time-dependent frequency (chirp signals) onto a set of wavelet functions as part of a wavelet thesaurus (wavelet dictionary), executing certain wavelet matching pursuit procedures, and displaying the CT scalar signals in a specific multidimensional medium of Cohen’s class time-frequency distributions. The simulation results in the form of the current trajectory (CT-) signals waveforms and their three-dimensional time-frequency representations as Wigner maps showing the UMV movement in a start-stop mode, as well as the signals of formed continuous deviation trajectories when they leave to the left and to the right from the NAT, are presented. An algorithm for the formation of 3D-representations of UMV current trajectory one-dimensional signals is presented. Conclusion. The conclusion is made that the mathematical technique of wavelet transforms is the most expedient and effective means for computer-aided monitoring and controlling the dynamics of UMV movement along routes within open pit roads.

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Section: Research Results Analysismentioning

confidence: 99%

The wavelet transforms technique in the computer-aided system for controlling the quarry unmanned vehicles

et al. 2021

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“…For informatively complete and semantically transparent processing the ACSS-and ECSS-signals, fragments were introduced into the software complexes of the latter, providing the formation of the so-called wavelet functions [15,16] and Cohen's class quadratic wavelet distributions [17][18][19].…”

Section: Modal Control Of the Umv Movement Along Technological Routesmentioning

confidence: 99%

Developing the concept of autonomous control of the quarry vehicles movement

et al. 2021

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Introduction. The article presents the results of studies related to the description of the synthesis and further analysis of the dynamic behavior of unmanned vehicles (UMVs) operating at coal opencast mines and other mining enterprises. The relevance of the research topic is dictated by the need to create safe and effective conditions for overburden / mining and mining transportation operations. This is ensured, among other things, by the operation of unmanned heavy-duty dump trucks. Purpose of the work: in the course of the research, a concept was developed for the formation of route parameters and models of the dynamics of movement of UMVs along technological routes. Methodology. The paper describes the technology for generating and processing signals in control subsystems as part of an automated dispatching system and an on-board subsystem for autonomous control of the UMV. Research methods include the study of the shapes and characteristics of current trajectories (CT) in relation to a nominal axial trajectory (NAT). In this case, a current trajectory of the UMV is considered within the framework of the so-called S-frames, which are formed as geolocations on a certain working UMV route from a bench face to the place of unloading and vice versa. As a variable characterizing the UMV behavior on a current trajectory, a 1D-signal with a time dependent frequency is adopted, the nature of the change of which is determined by the CT dynamic shape relative to the NAT. Results. Such chirp signals – together with the wavelet transforms technique introduced into consideration – allow us in a semantically transparent and information-rich videographic form to display and subject to further processing signals characterizing the current behavior of a UMV on a route. The resulting parameters of such secondary wavelet representations of the current UMV dynamics (wavelet maps) are further planned to be used in the subsystem of dynamic modal control of the UMV movement in the open pit. Conclusions. The results of the studies carried out make it possible to form current routes of UMV movement according to the models generated based on the analytical tools accompanying the dynamics of the UMVs, proposed in the work.

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“…Furthermore, time-frequency domain analysis has been proposed to retrieve more accurate and comprehensive information. The time-frequency domain method frequently utilizes techniques such as short-time Fourier transform (STFT), wavelet transform, Hilbert-Huang transform (HHT), Wigner-Ville Distribution (WVD) and Cohen Class Distributions [35][36][37][38]. STFT exhibits limited time resolution due to its fixed window width.…”

Section: Introductionmentioning

confidence: 99%

“…Although the HHT shows promise as a valuable tool for extracting features from non-stationary signals, it encounters challenges in system identification due to the generation of spurious modes and susceptibility to mode mixing [40]. Conversely, the computational complexity of the WVD renders it impractical for large datasets due to its complexity [38]. Cohen Class Distributions may introduce cross-term interference, particularly problematic when analyzing multi-component signals [38].…”

Section: Introductionmentioning

confidence: 99%

“…Conversely, the computational complexity of the WVD renders it impractical for large datasets due to its complexity [38]. Cohen Class Distributions may introduce cross-term interference, particularly problematic when analyzing multi-component signals [38]. Comparatively, the continuous wavelet transform (CWT) offers excellent resolution in both the time and frequency domains.…”

Section: Introductionmentioning

confidence: 99%

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Thin Copper Plate Defect Detection Based on Lamb Wave Generated by Pulsed Laser in Combination with Laser Heterodyne Interference Technique

Wang,

Zhu,

Guo

et al. 2024

Sensors

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Thin copper plate is widely used in architecture, transportation, heavy equipment, and integrated circuit substrates due to its unique properties. However, it is challenging to identify surface defects in copper strips arising from various manufacturing stages without direct contact. A laser ultrasonic inspection system was developed based on the Lamb wave (LW) produced by a laser pulse. An all-fiber laser heterodyne interferometer is applied for measuring the ultrasonic signal in combination with an automatic scanning system, which makes the system flexible and compact. A 3-D model simulation of an H62 brass specimen was carried out to determine the LW spatial-temporal wavefield by using the COMSOL Multiphysics software. The characteristics of the ultrasonic wavefield were extracted through continuous wavelet transform analysis. This demonstrates that the A0 mode could be used in defect detection due to its slow speed and vibrational direction. Furthermore, an ultrasonic wave at the center frequency of 370 kHz with maximum energy is suitable for defect detection. In the experiment, the size and location of the defect are determined by the time difference of the transmitted wave and reflected wave, respectively. The relative error of the defect position is 0.14% by averaging six different receiving spots. The width of the defect is linear to the time difference of the transmitted wave. The goodness of fit can reach 0.989, and it is in good agreement with the simulated one. The experimental error is less than 0.395 mm for a 5 mm width of defect. Therefore, this validates that the technique can be potentially utilized in the remote defect detection of thin copper plates.

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Cohen’s Class Time-Frequency Distributions for Measurement Signals as a Means of Monitoring Technological Processes

Cited by 5 publications

References 11 publications

The wavelet transforms technique in the computer-aided system for controlling the quarry unmanned vehicles

The wavelet transforms technique in the computer-aided system for controlling the quarry unmanned vehicles

Developing the concept of autonomous control of the quarry vehicles movement

Thin Copper Plate Defect Detection Based on Lamb Wave Generated by Pulsed Laser in Combination with Laser Heterodyne Interference Technique

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