Sine Signal Research Articles

A linear ultrasonic motor with a hollowed and symmetrical stator

A linear standing-wave ultrasonic motor with a hollowed and symmetrical stator is proposed in this study. The stator is cut from a cuboid block to produce a hollow and symmetrical structure, in which four thin-walled beams are formed on each end of the stator. Four driving feet are circumferentially installed at each end of the stator to guide the movement of the mover, and this design can simplify the guide rail and preload mechanism, which is beneficial to realize further miniaturization. Besides, the bi-directional motions are separately achieved by only using one sine signal to excite the same order vibration of the two groups of the thin-walled beams, which is conducive to the characteristic consistency of the bi-directional motions. Then, the finite element method is used to determine the parameters of the motor, the prototype is fabricated, and the output characteristics are tested. The experimental results show that the maximum no-load velocity, resolution, and maximum carrying load of the prototype in the forward motion were 30.86 mm/s, 0.5 μm and 39 mN, respectively; while that in the backward motion were 32.31 mm/s, 0.7 μm and 33 mN, respectively. This work sheds a new light on the design of the linear bi-directional standing-wave ultrasonic motors, simplifying the guide rail and preload mechanism and utilizing only one signal and the same order vibration to realize the bi-directional motions.

A Novel All-Digital Resolver-to-Digital Conversion System Based on Numerical Synchronous Integration

Resolvers are universally employed as absolute angle sensors in motor control systems. Detecting the synchronous envelopes is an essential step during the Resolver-to-Digital Conversion (RDC) process when calculating the angle. However, conventional filter-based envelope detection could introduce enormous angle delay and peak capturing-based detection could lead to apparent quantization angle error. A novel all-digital RDC system is proposed in this paper with the synchronous envelopes detected based on numerical synchronous integration method. The sine and cosine signals are oversampled and then multiplied by the excitation signal before integration to derive the envelopes. The angle delay and quantization errors could thus be largely reduced compared with RDC systems based on conventional envelop detections. In the experiment, angle error is limited to less than 30 arc min at the angular speed of 1000 rpm.

Experimental study on vibration suppression for robotic milling using an MRE absorber

During the robotic milling process, vibration is one of the main factors that affect the machining accuracy and surface quality due to the low stiffness of the robot structure. Intelligent material, magneto-rheological elastomer (MRE), owns the features of adjustable stiffness, reversible and fast response, has been gradually used for vibration suppression. Therefore, to suppress the forced vibration for robotic milling, this paper used the principle of vibration absorption and combined it with MRE material to design a snubber. A series of excitation and milling experiments were carried out to evaluate its vibration attenuation characteristics. In the excitation experiment, sine signals with frequencies of 40 Hz, 42.02 Hz and 60 Hz with the same amplitude of 5 N were applied to the MRE absorber. In the milling experiment, the dominant frequencies under speeds of 800 RPM, 840 RPM and 1200 RPM were analyzed first. Then, the vibration mitigation characteristics of the MRE absorber during robotic milling of aluminum alloy were explored by adjusting the current. Experimental results showed that under the action of MRE absorber, the acceleration responses are suppressed effectively. In detail, after tuning the current, the amplitude and the root mean square of vibration acceleration in three directions of sinusoidal excitation could be suppressed by more than 19.23% and 7.35% correspondingly. The power spectral density value of the peak frequency could be reduced by more than 69.13%. In milling experiments, the MRE absorber also achieved certain vibration absorption effects. Furthermore, the surface roughness of the workpiece was also fallen by more than 16.51% which provides support for further engineering application in the field of robotic milling. Undoubtedly, the absorber needs further optimization to achieve better vibration suppression ability and a larger working bandwidth.

Sensorless microcontroller-based zero-crossing detection system for AC signals using a rounding function

Microcontroller-based methods for zero-crossing detection (ZCD) presented in the literature employ external integrated circuits (ICs) to sense electrical signals, and their algorithms are sophisticated. Therefore, this paper proposes a simple open-loop sensorless microcontroller-based algorithm for determining zero-crossing (ZC) instants of sinusoidal signals that can be used for phase detection (PD) in phase-locked loops (PLLs). The proposed algorithm employs a built-in rounding function in the Arduino software environment. The developed system was simulated using MATLAB Simulink® to demonstrate its prominent features in recognizing zero-crossing points in two cases: a pure sine signal at a grid frequency of 50 Hz, and distorted signals with total harmonic distortions (THDs) of 10 %, 20 %, 30 %, and 40 %. In the simulation, the proposed system exhibited outstanding results in terms of simplicity, accuracy, and robustness. However, in practice, accuracy and robustness are relative terms, because they depend on the specifications of the microcontroller board. In this study, a low-cost microcontroller board, Arduino Uno, was used. The Uno is an 8-bit board with a 16-MHz clock speed. Therefore, an error in terms of the phase shift emerged in the output signal, which was measured to be 0.0314 rad at 50 Hz. Moreover, the proposed system detected the ZC points of distorted signals with a THD of up to 30 % without using filters and failed at a THD of 40 %. Finally, the ZC points were identified in a three-phase system, and the validity of applying the proposed method to polyphase systems was demonstrated.

Parameter Estimation of Linear and Nonlinear Systems Connected in Parallel

Presently, the problem of parameter estimation is addressed for a more general nonlinear model. In this respect, the proposed nonlinear system is composed of the parallel connection of linear and nonlinear blocks. The interconnected structure of linear and nonlinear blocks systems leads to a highly nonlinear problem involving several unknown parameters and inaccessible internal signals. In this parameter estimation method, the linear and nonlinear block parameters are estimated in one stage by using simple a sine signal or multi-cosine wave.

Phase Demodulation Strategy Based on Kalman Filter for Sinusoidal Encoders

Phase demodulation strategy based on Kalman filter for sinusoidal encoders is proposed in this paper. For the state equation and observation equation in the constructed phase demodulation model, the phase angle, the phase angular speed, and the speed fluctuation are the system states, and the sine and cosine signals output by the encoder are the system observations. In addition, due to the nonlinear relationship between the observations and the system states, the observation function is linearized by the extended Kalman approach. In order to implement the Kalman filter on the hardware platform with a field programmable gate array (FPGA), the matrix model of the Kalman filter is further derived into an algebraic model, which only contains sine, cosine, and basic algebraic operations. Compared to the arctangent method, the proposed method has the noise suppression capability, and compared to the conventional phase-locked loop (PLL) method, the proposed method has the better dynamic performance without the acceleration-associated phase error. Both simulation and experimental results can prove the effectiveness of the proposed method.

ЗАВИСИМОСТЬ СПЕКТРАЛЬНЫХ ХАРАКТЕРИСТИК СИГМА-ДЕЛЬТА АНАЛОГО-ЦИФРОВЫХ ПРЕОБРАЗОВАТЕЛЕЙ ОТ ПОГЛОЩЕННОЙ ДОЗЫ ИОНИЗИРУЮЩЕГО ИЗЛУЧЕНИЯ

This paper presents the results of the study of sigma-delta analog-to-digital converters` main spectral parameters` dependence on the total ionizing dose (TID). Within the framework of this study the main parameters of analog-to-digital converters (ADC) (dynamic, static and electrical) were controlled. The main dynamic characteristics of sigma-delta ADC are signal-to-noise ratio (SNR), spurious-free dynamic range (SFDR), signal-to-noise and distortion ratio (SINAD) and total harmonic distortion (THD). Those have been determined from the spectrum of digitized sine signal using the fast Fourier transform (FFT). Static parameters (integrated nonlinearity (INL), offset and gain errors) were determined using a straight line that linearizes the transfer function, according to the method which is described in the IEEE Standard for Terminology and Test Methods for Analog-to-Digital Converters. National Instruments modular measuring equipment was used for testing ADC`s parameters. Comparative data on the dose dependence of static and dynamic parameters of two sigma-delta ADC and one sigma-delta modulator are obtained. Based on the results, it was concluded that the most sensitive parameters of sigma-delta ADC to TID are its dynamic parameters. Therefore, when assessing the sigma-delta ADC`s radiation hardness, the spectral characteristics of absorbed dose should be kept under control.

Research on STM32-Based Signal Conditioning System Measurement System

The measurement of the signal modulation system is a vital part of channel transmission signal technology, which has a very important position in the signal communication quality assurance system. With the development of radio communications in modern radio technology, the research of AM and FM signal modulation measurement methods has become an important element in this field of research. This research is a signal modulation system using an STM32F407 microcontroller as the control core. The hardware of the system is mainly composed of a coherent demodulation circuit system and a comparator judgment circuit system, and the coherent demodulation circuit system is divided into AM demodulation circuit system and an FM demodulation circuit system. The frequency of the input signal was measured by a comparator, and the frequency change was used to initially determine the signal type. In which the modulating signal of AM signal was obtained by DDS generating separate orthogonal sine and cosine signals with the input signal through a series of operations, while the FM signal was operated with the sine signal. Finally, the amplitude and frequency information of the FM signal was obtained through the comparator, and finally reduced to the modulating signal of the FM signal. Output demodulated signal, its signal waveform without obvious distortion apparent phenomenon. Promotes the prospect of using the calibration of AM and FM signal generators in the field of communication.

Effect of Excitation Signal on Double-Coil Inductive Displacement Transducer.

A double-coil inductive displacement transducer is a non-contact element for measuring displacement and is widely used in large power equipment systems such as construction machinery and agricultural machinery equipment. The type of coil excitation signal has an impact on the performance of the transducer, but there is little research on this. Therefore, the influence of the coil excitation signal on transducer performance is investigated. The working principle and characteristics of the double-coil inductive displacement transducer are analyzed, and the circuit simulation model of the transducer is established. From the aspects of phase shift, linearity, and sensitivity, the effects of a sine signal, a triangle signal, and a pulse signal on the transducer are compared and analyzed. The results show that the average phase shift, linearity, and sensitivity of the sine signal were 11.53°, 1.61%, and 0.372 V/mm, respectively; the average phase shift, linearity and sensitivity of the triangular signal were 1.38°, 1.56%, and 0.300 V/mm, respectively; and the average phase shift, linearity, and sensitivity of the pulse signal were 0.73°, 1.95%, and 0.621 V/mm, respectively. It can be seen that the phase shift of a triangle signal and a pulse signal is smaller than that of a sine signal, which can result in better signal phase-locked processing. The linearity of the triangle signal is better than the sine signal, and the sensitivity of the pulse signal is better than that of the sine signal.

Modeling of Acoustic Emission Wave and Its Parametric Characterization Based on Peak Sensor Sensitivity on an Aluminum Block

In this paper an acoustic emission (AE) signal has been generated analytically for a homogenous material with a surface load. For the validation of the AE theory, a simulation for a developed AE wave has been conducted with computational algorithms. Experimental validation for the AE wave generation and propagation have also been performed under similar conditions. Aluminum metal block has been selected as the homogenous propagation medium for both simulation and the experiment. A function generator has been used for the excitation of a burst sine signal on the surface. A piezoelectric AE resonance sensor receives the vertical response due to the vertical load of the function generator. The algorithm of Lamb's solution has been employed in the generation of a simulated AE wave. As the transfer function, the peak sensor sensitivity of the AE sensor (R15alpha) has been incorporated along with the acoustic impedance of the metal surface and sensor. For both detected and simulated AE waves, the signal parametric characterizations have been performed based on the rise time and the maximum amplitude. The attenuation properties of the maximum amplitude and the increase of rise time with the increment of source to sensor distance has been evaluated to validate the proposed method.

Current measurement method based on integral reconstruction of magnetic rotation angle

In view of the nonlinear limitation of the sine function on the magnetic rotation angle in the optical current sensor based on the light intensity detection mode, this paper proposes a current measurement method based on the integral reconstruction of the magnetic rotation angle, thus avoiding the large current measurement error caused by the approximate linear measurement of the magnetic rotation angle. In this method, the cosine term in the derivative of the sine signal containing the magnetic rotation angle is eliminated by the constant deformation of the trigonometric function, and then the magnetic rotation angle is reconstructed by integration. The experimental results show that within the current range of 0.20 Arms to 2.40 Arms, the measurement error of the current value of the integral reconstruction method is less than 1.30%, the measurement error is less than the approximate linear measurement method, and there is a good linear relationship between the magnetic rotation angle and the current, with a linearity of 99.987%.

Novel Low-Speed Measuring Method Based on Sine and Square Wave Signals

This paper presents a novel low-speed measuring method using analog sine and square waves of Hall effect speed sensors coupled with correlative digital signal processing algorithms packaged on a signal processing unit. The frequency of the initial signal is estimated by a square wave period measuring method (SWPM). On the basis of the initially measured frequency, a recursive self-correction (RSC) algorithm is used to perform the low-frequency measurement using the discrete sinusoid wave. The low-speed signal frequency can be derived continuously from the phase difference of the discrete sine wave, where the RSC algorithm is used to achieve high measuring accuracy. Compared to the method using only the SWPM algorithm, this novel low-speed measuring method enables faster measuring speed to achieve sufficient real-time performance. Simulation analyses and experiments verified the effectiveness of the proposed low-speed measuring method.

Vibration acoustic modulation for bolt looseness monitoring based on frequency-swept excitation and bispectrum

The monitoring of bolt looseness is crucial to ensure the safety and reliability of structures. Prior studies have demonstrated that the vibro-acoustic modulation (VAM) method based on the nonlinear ultrasonic theory is sensitive to the early looseness of bolted connections. However, one limitation of the traditional VAM method is that the low frequency (LF) and high frequency (HF) for excitation should be specified in advance. The resonant frequency of the bolted structures changes after loosening, leading to inaccuracies in monitoring results if pre-specified excitation frequencies are used and not adapted to the new situation. To address this limitation, this paper improves the VAM method by using swept sine signals for both LF and HF excitations and relying on the bispectrum energy of the measured response to indicate the bolt pre-load. A steel bolted connection was fabricated and loaded on a universal testing machine to simulate different bolt pre-loads. Three low-cost lead zirconate titanate patches served as the LF actuator, HF actuator and sensor in the experiment. The experimental results demonstrate that the improved VAM method can evaluate the bolt looseness with better efficiency and robustness than the traditional VAM methods which use fixed frequencies as excitations. Therefore, the proposed method in this paper can potentially monitor the damages in complex structures based on nonlinear ultrasound theory.

Development of a Reference Device for the Calibration of Optical One-Shot Time-Interval Measurements

This paper presents the development of a device that creates two or more light pulses with a precision time delay in a range from microseconds to several seconds and for the purpose of the calibration of velocity of detonation (VOD) measurement instruments. The device was assembled, programmed, and tested for functionality. Measurements were conducted using a reference counter. First, a precision OCXO (oven-controlled crystal oscillator) was used as a clock source. For verification of programmed subroutines, a counter oscillator output port was used as a source of clock signal for the microcontroller. This enabled the cancellation of possible oscillator errors. The signal had to be converted from an AC sine signal to a signal with positive values only using a clamper circuit. By the proposed solution, a calculable standard of time delay between two light pulses was achieved. According to the obtained results, this device can be used to calibrate field measurement devices for VOD measurements in explosives or some other use where the measurement device records the time interval between multiple light pulses. This enables more confidence in measurement results, faster recognition of instrument drift and increases the quality of measurement.

Characterization and Prediction of Speech Intelligibility at the Output of Hearing Aids in a Noisy Working Environment.

Hearing aids are more and more technically advanced, but do not necessarily guarantee the reproduction of useful signals in all working environments. This is particularly the case for speech intelligibility. This study focuses on the prediction of hearing aid performance in the case of a moderate deafness setting, in service and industrial work environments. To improve intelligibility, hearing aids propose signal processing options such as noise reduction and compression. These processes can transform hearing aids into nonlinear systems. The aim of this study is to develop a nonlinear method for the characterization of hearing aids. The method is based on the synchronized swept sine (SSS) signal method.[16] The SSS method is applied for determining hearing aid frequency responses fitted according to the present methodology and several processing options. The characterization of hearing aid's program containing the noise reduction function is specifically analyzed. Indeed, to be fully active and efficient, the hearing aid, with the noise reduction feature activated, needs to be immersed in a noisy environment which does not allow nonlinear characterization. A linear approach is taken to study this feature. Three hearing aids commonly sold by hearing care professionals are studied here; all of them have three different programs. The characterization for each program is discussed. The statistical study showed that the intelligibility, assessed using the speech transmission index in these sound environments, is well estimated for every program, although certain differences are observed when the compression effect is too high in the service work sector. The characterizations of hearing aids using the programs studied did not highlight the presence of frequency nonlinearities. The characterization method could not take into account amplitude nonlinearities when there is too much gain compression in the hearing process. Globally, all the hearing aid programs provided a very significant improvement in intelligibility in service and industrial work contexts.

Frequency domain parametric estimation of fractional order impedance models for Li-ion batteries

The impedance of a Li-ion battery contains information about its state of charge (SOC), state of health (SOH) and remaining useful life (RUL). Commonly, electrochemical impedance spectroscopy (EIS) is used as a nonparametric data-driven technique for estimating this impedance from current and voltage measurements. In this article, however, we propose a consistent parametric estimation method based on a fractional order equivalent circuit model (ECM) of the battery impedance. Contrary to the nonparametric impedance estimate, which is only defined at the discrete set of excited frequencies, the parametric estimate can be evaluated in every frequency of the frequency band of interest. Moreover, we are not limited to a single sine or multisine excitation signal. Instead, any persistently exciting signal, like for example a noise excitation signal, will suffice. The parametric estimation method is first validated on simulations and then applied to measurements of commercial Samsung 48X cells. For now, only batteries in rest, i.e. at a constant SOC after relaxation, are considered.

Weak-light phase locking aided by frequency division phase meter for intersatellite laser interferometry

Weak light phase locking is an important part of intersatellite laser interference ranging. Phase-locked loop (PLL) is used to track the phase of heterodyne interference optical signal. Owing to shot noise, laser frequency and other kinds of noise, there is a phase difference between the internal PLL local oscillator and the heterodyne signal, while the phase detection range of the PLL is only one period. If the phase difference exceeds the phase detection range at a certain time, the local oscillator may enter the wrong operating point under feedback regulation, resulting in cycle clip, which leads to subsequent phase reconstruction errors. In this paper, a cycle clip diagnosis method based on the detection background of gravitational waves is proposed. Based on the original PLL, an auxiliary frequency phase divider with larger phase detection range is introduced, which can provide a basis for judging whether the cycle clip occurs in the PLL. In this paper, a digital weak-light PLL model is established to evaluate the influence of various noise. The theoretical spectral density of the error phase is given according to the two main kinds of noise (laser phase noise and particle noise). Considering the limited detection range of PLL, large error phase may lead to cycle clip, making the PLL work at the wrong locking point. A phase meter with smaller frequency division phase range can be used to solve this problem. First, the input heterodyne sine signal is converted into in-phase square wave N frequency division. Then the phase difference is determined by comparing the output signal with output signal reduced by 1/<i>N</i> through the time-to-degital converter (TDC) Based on the theory of PLL and noise, the theoretical model of frequency division phase meter is established. The simulation results show that the frequency division phase meter can realize a wide range of phase detection under the current theoretical framework and has the ability to judge the cycle clip of weak light phase locking. It can be used in the weak- light phase locking task represented by LISA.

Multi-voltage threshold digitizer using a time-varied threshold for photon-counting X-ray security inspection imaging

In this paper, we present a multi-voltage threshold (MVT) digitizer using a time-varied threshold and investigate the feasibility of using this digitizer to develop the data acquisition system for photon-counting X-ray security inspection imaging. This digitizer compares the scintillation pulse with a preset time-varied voltage signal and records the time information of the intersections. As the amplitude of the threshold varies as a function of time, the voltage values of the intersections could be calculated using the recorded time, and the energy information could be extracted via the acquired time–voltage samples. Unlike the constant voltage thresholds MVT digitizer requiring multiple voltage comparators, this method needs only one voltage comparator, which notably reduces the complexity in configuration. We demonstrate the development of such an MVT digitizer using a sine signal threshold and evaluate its energy performance with a yttrium orthosilicate (YSO) scintillator and Silicon Photomultiplier (SiPM) detector (designed for X-ray detection). The digitizer obtains energy resolutions of 41.4%, 26.6%, and 25.5% at 30, 59.5, and 80.9 keV, respectively. For comparison, the YSO/SiPM detector is also evaluated with a high-speed oscilloscope, and measured energy resolutions are 40.6%, 26.5%, and 25.1% at 30, 59.5, and 80.9 keV, respectively. These results indicate that the proposed MVT digitizer using a time-varied threshold is a promising method for developing a YSO/SiPM-based photon-counting X-ray detector.

Effect Analysis of Step Input Smoothing Optimization on Hydraulic Excitation Suppression of Position Servo System

Based on step input ramping optimization, a further optimization method is proposed by superimposing a sine signal to smooth the mutation of the step signal. This sine smoothing method has zero signal change rate and acceleration at the beginning and the end of the signal mutation. That is, the optimization has good smoothing characteristics. With the position servo system as the research object, the simulation model is established and the effect analysis of parameters such as rising time, friction, and external load is carried out. It can be concluded based on the analysis that the ramp and the sine smoothing optimizations are very effective in reducing hydraulic excitation, especially in suppressing the pressure pulsation of the system; meanwhile, it would cause a system response millisecond delay. Different optimization methods should be selected according to the specific application scenarios.

Reconstruction of QPSK Modulation Digital Communication Learning with Rewiring Modicom 5/1 and Modicom 5/2

Communication systems are very decisive in modern warfare, the use of long-range weapons without crew requires a long-distance communication system using digital modulation communication. One of the basics of digital modulation communication that is important is QPSK modulation, so the Department of Electronics develops learning by conducting research on QPSK modulation and demodulation by conducting research on series block systems built on Modicom 5/1 and Modicom 5/2. Modicom 5/1 consists of blocks, namely the separation of serial data into MSB and LSB data, Unipolar to bipolar converters, Modulator I and Modulator Q and the summation of the Op-Amp. The Modicom 5/2 consists of a QPSK detector, a two-order filter, a comparator and a decoder differential. The results of the study prove that serial data from modicom 3/1 is in the form of serial data (D0,D1,D2,D3,D4,D5) separated by MSB data separator blocks (D0,D2,D4) and LSB (D1,D3,D5), serial data MSB and LSB (unipolar data standard (0V/+5V)) are converted to bipolar standard digital data (-4V/+4V) by a unipolar to bipolar converter block system. Balance Modulator (IC 1496) with MSB signal input ( I ) on modulator 1 carrier frequency of 960kHz (∟0º) and 960 kHz (∟-180º) on modulator 2 is LSB (Q) will output data in the form of an analog sine signal with a frequency of 960 KHz with different phase according to carrier signal '0'=∟-90º or '1'=∟-270 . the sum of the Module I and Q signal modules into phase angles of 00(45º),10(135º),11(225º), 01 (315º). The QPSK detector by means of the information signal is generated 4 times, the phase is detected (IC PLL) then divided by 4 , phase difference angle as control switch signal I and Q to get signal I and signal Q . The I and Q signals are filtered by fourth order butterworth then the I and Q signal data as comparator inputs to get a logic 0 or 1. Data I and O as logic data (0/1) as MSB and LSB data are combined again into discrete serial data with blocks differential decoder by using the PISO register (parallel input serial output) using IC 17HC175.