Excitation Signal Generation Research Articles

Design of a multidimensional data collection system based on DRS4 scheme

A high-speed data acquisition system based on DRS4 waveform digitization is designed to meet the requirements of high sampling rate, multi-parameter measurements, and long-distance transmission in some particle physics experiments. The system consists of a waveform digitization front-end board, a high-speed data transmission board, and an upper computer software. Test results show that the system has a high data transmission rate and a low BER and that the collected data can reconstruct and restore the input signal waveform well. In addition, we have analyzed the single-electrode dual-mode sensor, excitation signal generation module, resistor/capacitor conversion circuit, and phase-sensitive demodulation unit in the system. The experiments show that the system is stable in operation, flexible in use, and can significantly extend the measurement range.

Performance Comparison of Meta-Heuristics Applied to Optimal Signal Design for Parameter Identification.

This paper presents a comparative study that explores the performance of various meta-heuristics employed for Optimal Signal Design, specifically focusing on estimating parameters in nonlinear systems. The study introduces the Robust Sub-Optimal Excitation Signal Generation and Optimal Parameter Estimation (rSOESGOPE) methodology, which is originally derived from the well-known Particle Swarm Optimization (PSO) algorithm. Through a real-life case study involving an Autonomous Surface Vessel (ASV) equipped with three Degrees of Freedom (DoFs) and an aerial holonomic propulsion system, the effectiveness of different meta-heuristics is thoroughly evaluated. By conducting an in-depth analysis and comparison of the obtained results from the diverse meta-heuristics, this study offers valuable insights for selecting the most suitable optimization technique for parameter estimation in nonlinear systems. Researchers and experimental tests in the field can benefit from the comprehensive examination of these techniques, aiding them in making informed decisions about the optimal approach for optimizing parameter estimation in nonlinear systems.

Optimal Design of Electromagnetic Tomography Flaw Detection System for Train Wheel Based on FPGA

Electromagnetic tomography (EMT) is a new type of nondestructive testing technology that can be used for metal flaw detection. The implementation of the signal demodulation and filtering algorithm of the current electromagnetic tomography flaw detection system relies on the microprocessor MCU, and the reliability is low in real time. To improve the reliability and system integration of signal processing and transmission of the electromagnetic tomography flaw detection system, this paper uses the field programmable gate array chip to integrate the excitation signal generation module and the digital demodulation module based on the EMT train wheel flaw detection system. A digital filter is designed, and the filter parameters are adjusted to achieve a signal-to-noise ratio of 15 dB. UDP communication protocol is utilized to realize Ethernet communication between FPGA and upper computer. Using three algorithms on the host computer for image reconstruction, the train wheel defect information is visualized. The experimental results show that the FPGA chip improves the immunity of the train wheel flaw detection system, realizes the high integration of the system, and achieves the purpose of train wheel defect detection.

Low-power vibrothermography detection technique for surface cracks on composite sucker rod

Composite sucker rods are becoming increasingly popular in oil fields owing to their light weight and corrosion resistance. However, various defects may appear in the manufacturing and service of sucker rods. Unfortunately, research on defect detection is still insufficient for composite sucker rods. This study explores a surface crack detection technique for composite sucker rods based on low-power vibrothermography (LVT). First, an improved low-power piezoceramic actuator with a curved bottom is designed for rod-like structure. Second, the entire processes of LVT-based surface crack detection, including excitation signal generation, mechanical wave propagation, and heat generation at defects, are simulated and analyzed using the finite element method. The heat generation mechanism and characteristic at cracks are revealed by coupled thermo-electro-mechanical analysis. The superiority of the improved actuator is reflected by comparison with the conventional actuator. In addition, the simulation investigates the optimal excitation signal amplitude and circumferential angle between the actuator and the crack. Finally, a series of LVT detection experiments were conducted on a composite sucker rod with surface cracks, which not only proved the effectiveness of the LVT, but also validated the conclusions of the numerical simulations. The maximum temperature rise at the crack is 5.54 °C by using the improved actuator. Numerical simulation and experimental results demonstrate that the surface cracks of the composite sucker rod can be effectively detected using LVT with an improved piezoceramic actuator. This study provides a new direction for extending vibrothermography to the non-destructive testing of composite rod-like structures.

Trends, Challenges, and Recent Advances in Electrochemical Impedance Spectroscopy

Impedance spectroscopy is considered one of the widely used smart analytical solutions for many electrochemical and biomedical applications. Recently, many research studies have been deployed to provide optimum system design architectures for biomedical and point-of-care diagnostic products. This letter introduces a supportive guide for readers to figure out trends, challenges, and recent advances in state-of-the-art electrochemical impedance spectroscopy, starting from the excitation signal generator that allows producing the corresponding electrical signal from the sensor. Then, readout analog front-end architectures, based on the extracted electrical signal, are presented. At the end of the signal chain, data analysis mechanisms are discussed and followed by concluding the authors’ recommendations for different macros.

A novel excitation signal generation technology for accelerated random vibration fatigue testing based on the law of kurtosis transmission

Based on the principle of signal decomposition, the law of kurtosis transmission between non-Gaussian excitation signal and structural response signal is studied, and the inherent relationship between the kurtosis of decomposed signal of excitation and response is found. On the basis of this relationship, a novel excitation signal generation technology for accelerated random vibration fatigue testing is proposed, which has been verified by simulation and experiment. The results show that excitation signal generated by this method can obtain the required high kurtosis response signal for accelerated random vibration fatigue testing, which can effectively reduce the time of accelerated life testing.

Design and Implementation of a Heating Treatment System for Vitiligo Skin Disease Based on Medical Ultrasound.

Vitiligo is relatively common clinically. It is an acquired and persistent skin and mucosal pigment depigmentation disease. As a noninvasive and nonradioactive treatment, high-energy ultrasound has been applied to skin diseases of vitiligo. Treatment achieved good clinical results. This article analyzes the structure of the original medical ultrasound system for vitiligo and finds the deficiencies and missing components of the system. On the basis of the original design scheme, a new structural scheme was designed, which solved the shortcomings of the original system and added missing parts. Subsequently, according to actual application requirements and specific component performance, the schematic design, including audio and video input, output and storage, DDR3, Ethernet, and the design of key circuits, such as power supply modules, are specifically introduced. Later, in the PCB design, the contents including stacking, layout, routing, and simulation of key signals were introduced in detail. The design includes a probe excitation signal generation module, excitation signal parameter control module, high voltage and temperature monitoring module, and corresponding power conversion module. This paper is mainly to develop a vitiligo skin disease heating treatment array system based on the principle of both cost and performance. This paper is based on the nonrigid registration algorithm of the FFD model and HPV interpolation and the nonrigid registration algorithm combining shape information and SIFT method. In the focused ultrasound treatment system, the image-guided positioning and monitoring functions are realized. Studies have shown that when the peak voltage of the transmitter circuit is 55 V, the sound power is 0.28 W. It can be seen that the transmitting circuit system designed in this article is a relatively stable and reliable system, which is suitable for the ultrasound treatment of vitiligo skin diseases.

Innovative Analysis for Parameter Estimation Quality

This paper performs an analysis of the solution space influence of a nonlinear dynamic system on the parameter estimation quality. For parameters estimation, the proposed approach uses an Optimal Input Design (OID) as the Suboptimal Excitation Signal Generation and Optimal Parameter Estimation (SOESGOPE). Based on the studies of a small mobile robot that is represented by a parametric mathematical model indicate that the model reliability level maximizes using the shortest set of parameters. Applications, qualities, and limitations of the method are analyzed considering the solution space. Through an in-depth analysis of the identification process of a differential mobile robot, the paper becomes a reference for a review of a nonlinear dynamic system, aiming to select the most suitable model for the identification process.

Recursive Approach of Sub-Optimal Excitation Signal Generation and Optimal Parameter Estimation

Optimal Input Design (OID) methodologies are developed to find a signal that could best estimate a set of parameters of a given model. Their application in constrained nonlinear systems, especially when the search space limits or the initial conditions are unknown, may present several difficulties due to the numerical instability related to the optimization processes. A good choice over the parameters possible ranges is a trade-off among numerical stability, search space size, and effectiveness, and it is hardly found. To deal with this problem, this paper proposes a series of changes in the Sub-Optimal Excitation Signal Generation and Optimal Parameter Estimation (SOESGOPE) methodology. First, the limits over the parameters are tightly adjusted according to their confidence. A recursive approach runs the optimization methodology, analyzes the solution’s feasibility and marginal costs given by the Lagrange Multipliers, and selects a direction that could improve the system’s response. This approach improves the convergence and the assertiveness of the estimation process. To validate this approach, some cases, including a parameters estimation of a mobile robot nonlinear system, are tested.

Persistently-exciting signal generation for Optimal Parameter Estimation of constrained nonlinear dynamical systems

This work presents a novel methodology for Sub-Optimal Excitation Signal Generation and Optimal Parameter Estimation of constrained nonlinear systems. It is proposed that the evaluation of each signal must also account for the difference between real and estimated system parameters. However, this metric is not directly obtained once the real parameter values are not known. The alternative presented here is to adopt the hypothesis that, if a system can be approximated by a white box model, this model can be used as a benchmark to indicate the impact of a signal over the parametric estimation. In this way, the proposed method uses a dual layer optimization methodology: (i) Inner Level; For a given excitation signal a nonlinear optimization method searches for the optimal set of parameters that minimizes the error between the outputs of the optimized and benchmark models. (ii) At the outer level, a metaheuristic optimization method is responsible for constructing the best excitation signal, considering the fitness coming from the inner level, the quadratic difference between its parameters and the cost related to the time and space required to execute the experiment.

Development of tools for real-time betatron tune measurements at the Nuclotron

A betatron tune measurement system was developed and tested at the Nuclotron. A white noise and chirp signals were used for transverse beam motion excitation. A custom FlexRIO digitizer module was developed which provides excitation signal generation for kicker electrodes and real-time signal acquisition from pickup electrodes. A high resolution FFT algorithm was implemented inside a NI PXI FPGA module, connected to digitizer. The measurement system is integrated with the NICA control system based on the TANGO Controls. Results and tests performed with the Nuclotron beam are presented.

Development of a Multichannel Pulser for Acoustic Scanning Microscopy

Modern ultrasound imaging techniques use arrays to manipulate an ultrasound beam and to gather additional information out of the reflected sound field by analysing the received signal of each channel. For further wide-ranging applicability it is required to achieve a higher resolution by increasing the frequency of excitation signals and improvement of the signal to noise ratio. Actually neither electronic hardware nor high-frequency arrays are available that meet these requirements, so that a further development of the control-electronics is indispensable.Therefor the ultrasound pulser presented in [1] was improved with respect to the generation of various excitation signals. A unit consisting out of 16 channels has been developed containing the technology to control these channels as well as to record and to process the received signals. It provides different types of excitation-functions with an excitation-frequency stepwise increasable up to 40MHz. Additionally the modularised layout allows an extension to control much more elements.All presented improvements are realised in a new ultrasound pulser that offers emission of arbitrary signals on each single channel. Of course the raw data of measurements are accessible and different optional data processing functions are selectable.

Research on the Dynamic Calibration of Thermocouple and Temperature Excitation Signal Generation Method Based on Shock-Tube Theory

This paper introduces the equipment for generating an excitation signal during the process of thermocouple dynamic calibration in air medium, with the objective of dealing with the problems existing extensively in the excitation signal of incapable assessment of the rising time and inaccuracy in the traceability for the step amplitude. Based on the shock-tube theory, the step-temperature excitation signal that is suitable for the dynamic calibration of the thermocouple with appreciable rising time, wide-frequency bandwidth, and traceable step amplitude can be generated by means of the improvement in the structure of the traditional shock tube as well as the compensation of the shock-tube parameters. Through on-site assessment experimentation and dynamic modeling of the thermocouple, the time constant of the thermocouple can be obtained and the dynamic response of the thermocouple can be modified and compensated, the calibration result of which shows that the dynamic calibration method of the thermocouple proposed in this paper can be implemented for different ranges of frequencies and different phases of the temperature sensor with high reliability; moreover, the calibration equipment is miniaturized.

Integrated Diagnostic and Preload Control for Ball Screw Drives by Means of Self-Sensing Actuators

Piezoelectric ceramics can be used as sensors, as well as actors. The concept of a self- sensing-actuator tries to use both modes of operation in one device, allowing the economic integration of mechatronic systems. Possible fields of application are ball screws of machine tools, where wear-induced degradation of the preload can be compensated. Furthermore, the signal processing part of such a system can be used to gather information related to the condition of the ball screw. Both excitation signal generation and filtering of the measured signal have to offer high flexibility and signal fidelity. In this article the concept of a power amplifier and its corresponding signal processing system are presented.

The Closed-Loop Identification of Dynamic Parameters Based on Rigid Model for the Feeding System of Commercial Numerical Control Machine

The precision of high-speed CNC (Computer Numerical Control) machine are greatly influenced by the dynamic characteristics of servo system. In this study, by investigating the motor of the servo system of CNC machine, an inertia and damping linear identification model is established using current as input signal and motor rotation velocity as output signal. Moreover, the excitation signal generation method based on G-code, concerning the closed-loop identification of servo system, is proposed. Furthermore, to verify the effectiveness of the closed-loop identification, an experiment is carried out on the feeding system of a commercial NC machine. The experiment results show that the proposed method performs well with effective stimulation, rapid convergence and accurate results.

Design of Ultrasonic Guided Wave Excitation Signal Generator for Rotating Shafts

Ultrasonic guided wave detection technology has mangy special characteristics. It can spread very far along the components in the distance and it can throughout the whole thickness of components, so we can make use of ultrasonic guided wave to test component of internal and surface defects. The rotating shafts are the organizations widely used in the modern production but they are very easy to be dangerous faults. If we can realize the rotating shaft in time, it can reduce the danger. It is significant to design an affordable generator which produces signals to drive magnetostrictive probe that produces ultrasonic guided wave. In this paper, we choose the torsional wave as example to design signal generator. We will introduce the way to select the appropriate guided wave mode and frequency of excitation. Design signal generator with ATmega32, AD9851 and DAC0832.

The Design of a Digital Magnetic Induction Tomography (MIT) System for Metallic Object Imaging Based on Half Cycle Demodulation

This paper presents several important aspects of a highly integrated, Field Programmable Gate Array (FPGA)-based digital Magnetic Induction Tomography (MIT) system for metallic object imaging applications. Excitation signal generation, receiving signal demodulation, and channel multiplexing control are all implemented inside a Xilinx FPGA (Spartan III). A novel digital demodulation method using only half of the signal cycle is proposed and implemented, which improves the operation speed of the system by two folds. A geometrical scaling relationship has been discovered for MIT sensors, and a particular design has been implemented. Two imaging reconstruction algorithms (Tikhonov Regularization and Total Variation method) are applied to experimental data. The performance of the system has been verified.

Generation of Non-Gaussian Random Vibration Excitation Signal for Reliability Enhancement Test

AbstractDuring environment testing, the time histories of some dynamic environments follow non-Gaussian distribution. It is always assumed that the random vibration simulated follows Gaussian distribution, because the traditional digital random vibration control system can only supply the random vibration excitation signal of Gaussian. To simulate the real environment of product, a method is developed in this paper that can generate non-Gaussian random signal with specified power spectrum density (PSD), skewness and kurtosis by shot noise. In this way, non-Gaussian random vibration can be produced on traditional electrodynamic shaker. It solves the problems of spectral valley and energy shortage in low frequency on omni-axis shaker. At last, the wavelet is used to analyze the non-Gaussian signal.

GENERATION AND PROCESSING OF ROBUST PERIODIC EXCITATIONS

The generation of robust periodic excitation signals to measure and identify the frequency response function of (linear) dynamic systems is studied. Such signals should result in a maximal signal-to-noise ratio in a given measurement time, have a low sensitivity to nonlinear distortions, while at the same time they should be user friendly and robust to misuse by inexperienced users. Random phase multisines are proposed that meet all these requirements: in one experiment not only the frequency response function is measured, also the disturbing noise levels at input and output are determined, and the nonlinear distortions of the plant are characterized.

스펙트럼 형태 불변 실시간 음성 변환 시스템

본 논문에서는 음성의 스펙트럼 형태는 유지하면서 음성을 기계적인 음성으로 변환시키기는 실시간 음성 변환 방법을 제안하였다. 이러한 목적을 위하여 LPC 분석 및 합성 방법을 사용하여 변환된 음성의 스펙트럼은 유지하였고 합성된 음성의 피치는 자유롭게 변경되도록 하였다. 제안된 방법에서는 변환된 음성이 보다 자연스럽게 들리게 하기 위하여 여기 신호 발생기에 이득 정합 방법을 적용하였다. 제안된 방법의 성능을 평가하기 위하여 음성 변환 실험을 수행하였다. 실험 결과에서 원 음성 신호는 원 화자의 신원을 알기가 어려운 기계적인 음성 신호로 바뀌는 것을 알 수 있었고 피치의 심한 변화에도 변환된 음성의 의미는 정확히 전달될 수 있었다. 제안된 시스템은 시스템의 실시간으로 구현될 수 있는지 확인하기 위하여 TI TMS320C6711DSK 보드를 사용하여 구현되었다. In this paper, the spectral shape invariant real-time voice change method is proposed to change one's voice to mechanical voice. For this purpose, LPC analysis and synthesis is used to maintain the spectraum of voice and the pitch of synthesis speech can be changed freely. In the proposed method, gain matching method is applied to excitation signal generator to make the changed voice natural to hear. In order to evaluate the performance of the proposed method, voice change experiments were conducted. Experimental results showed that original speech signal is changed to the mechanical voice signal in which context of the speaker's voice is conveyed correctly in spite of drastic change of pitch. The system is implemented using TI TMS320C6711DSK board to verify the system runs in real time.