Vibration Error Research Articles

Laser Beams-Based Localization Methods for Boom-Type Roadheader Using Underground Camera Non-Uniform Blur Model

The efficiency of automatic underground tunneling is significantly depends on the localization accuracy and reliable for the Boom-type roadheader. In comparison with other underground equipment positioning methods, vision-based measurement has gained attention for its advantages of non-contact and no accumulated error. However, the harsh underground environment, especially the geometric errors brought by the vibration of the machine body to the underground camera model, has a certain influence on the accuracy and stability for the vision-based underground localization. In this paper, a laser beams-based localization methods for the machine body of Boom-type roadheader is presented, which can tackle the dense-dust, low illumination environment with the stray lights interference. Taking mining vibration into consideration, an underground camera non-uniform blur model that incorporate the two-layer glasses refraction effect was established to eliminate vibration errors. The blur model explicitly reveals the change of imaging optical path under the influence of vibration and double layer explosion-proof glass. On the basis of this, the underground laser beams extraction and positioning are presents, which is with well environmental adaptability, and the improved 2P3L (two-points-three-lines) localization model from line correspondences are developed. Experimental evaluation are designed to verify the performance of the proposed method, and the deblurring algorithm is investigated and evaluated. The results show that the proposed methods is effective to restore the blurred laser beams image that caused by the vibration, and can meet the precision need of roadheader body localization for roadway construction in coal mine.

A comprehensive alleviation technique for optical‐turbulence‐induced errors in vision‐based displacement measurement

Computer vision-based displacement measurement techniques can be affected by the optical turbulence in the field in hot weather. The optical turbulence can be observed naturally when viewing a thick layer of heated air. The nonuniform density distribution of the air due to heat creates spatial variations in refraction indexes, resulting in distortions in video images and measurement errors in displacements obtained from distorted videos. The effect of optical turbulence on vision-based displacement sensing is first illustrated in the field test conducted in hot weather. Then, the statistical characteristics of the optical-turbulence-induced measurement errors are analyzed and confirmed. And a comprehensive optical-turbulence error alleviation technique, which has two steps, is designed based on the statistical studies. A previously developed high-performance multitarget vision-based displacement measurement technique is utilized in the first step to track multiple targets. Distortions of multiple targets are estimated simultaneously continuously. Targets with the least distortions in each frame are identified and their displacements are extracted as the primary displacement. To further alleviate errors in the primary displacement, an adaptive optical-turbulence error filter is formulated in the second step based on the statistical characteristics of the optical-turbulence errors. Validations of the optical-turbulence error alleviation technique are performed in both laboratory and field tests. Field tests are conducted on the Williamsburg Bridge in the natural environment. After alleviating optical-turbulence and camera vibration errors, frequency domain analyses are conducted on vibrational displacements of the Williamsburg Bridge in response to train passing.

Identification of the vibration error of the navigation accelerometer during its static tests

This article describes the vibration error of the navigation accelerometer caused by the nonlinearity of its metrological model.Vibration error is the regular steady-state error in the time-average output of accelerometer during vibratory disturbances. It is defined that error varies with the amplitude and frequency of the vibrations and consists of additive and multiplicative components. The additive components are only dependent on the vibration value and determined by even nonlinear coefficients. The multiplicative components are also dependent on measured acceleration and determined by the asymmetric of sensitivity, odd nonlinear coefficients, and cross-sensitivity. To express these dependencies, an appropriate mathematical model was developed.The method of experimental estimation of the vibration error based on the developed model was proposed. The main idea of the method is to evaluate parameters of the developed model during static tests in the terrestrial gravitational field and to calculate error according to the specific vibration characteristics – the amplitude in the case of harmonic vibration profile or the frequency band and the power spectral density in the case of random vibration.The effectiveness of the proposed method has been tested by using three types of navigation accelerometers in comparison with the results of classical dynamic testing in various vibration conditions (harmonic, white noise, etc.). The mismatch between the calculated values of the vibration error and the reference results did not exceed 35%, which confirms the correctness of reasoning regarding the type of proposed functional dependence.

Angle error from vibrating in tri-axial interferometric fiber optic gyroscopes and the evaluation with dual-laser Doppler vibrometers

Abstract In this paper, we accurately obtained the depolarized interferometric fiber optic gyroscope (D-IFOG) output error caused by elasto-optic effect in vibration environment. We established the optical transmission model of D-IFOG and simulated the stress distribution of D-IFOG caused by vibration based on finite element method. The computational results show that the angular velocity error has a phase difference of 90° with the sinusoidal excitation, and when the vibration’s amplitude is 4 g and the frequency is 70 Hz, for triaxial D-IFOGs, the maximum angle error of Y-axis is up to 3.54 × 10−4°, and that of X-axis and Z-axis is 6.26 × 10−5°. And we set up a high-precison dynamic angular measurement system based on dual-laser Doppler vibrometers to evaluate the angular error in D-IFOGs. The experimental results are consistent with those of numerical simulations, which have verified the angle error model. This work is meaningful for the follow-up D-IFOG’s vibration error compensation.

Inverse dynamic control via “simulation of feedback control” by artificial neural networks for a crane system

Cranes are systems highly used in industrial applications to transport heavy loads. The nonlinear behavior, and the crane own dynamic produce vibrations during the motion. In order to improve the system performance and specifically to ensure stability and a control with minimum vibrations, this work proposes a new strategy based on IDCS (Inverse Dynamic Control Simulation) using machine learning with Artificial Neural Networks ANN that gives the possibility to learn the inverse dynamic model of the crane and apply the feedback information based on the inverse dynamic control simulation. IDCS allows a suitable signal control avoiding noise and need for extra sensors in the feedback loop. The ANN creates the inverse dynamic model of the crane. The training architecture is developed to learn the inverse dynamic model of the crane in different operational points, and is used as feedforward control with the feedback dynamic in the IDCS scheme. Simulations and experiments are conducted with an industrial crane, and results show that the proposed method decreases vibration and position error. The proposed ANN-IDCS showed suitable performance compared to other controllers such as analytical inverse model control (AIC), Dual Matching Control (DMM) and shaped reference in feedforward (FRC).

Modeling and analyzing point cloud generation in missile-borne LiDAR

The missile-borne LiDAR has an essential prospect in precise guidance. However, the instability of the missile has a significant impact on the precision of LIDAR point cloud, thus modeling and analyzing the influencing factors of point cloud generation is necessary. In this investigation, the authors modeled the point cloud calculation process of missile-borne linear array scanning LiDAR under ideal conditions and analyzed the effect of position change on the field of view (FOV) in the course of platform motion. Subsequently, the authors summarized that the stability concerning the field of view and the target tracking are dependent on three limiting conditions. Finally, the authors derived an error formula and analyzed several typical errors in missile platform flight, including scanner error, POS error, system integration error, and platform vibration error. Based on theoretical analysis and simulation experiments, the model proposed in this paper can provide a theoretical basis for the design of the missile-borne LiDAR system and the selection of related instruments in practice.

Techniques for vibration resistance increase of quartz pendulum accelerometer using digital feedback amplifier

Subject of Research. The paper considers approaches of vibration resistance increasing for quartz pendulum accelerometer with digital feedback amplifier and without further development of measuring element design or application of damping measures. Method. The proposed methods are implemented algorithmically by means of the control program of the digital amplifier controller and are based on the extension of the device bandwidth, the correction of the regulating coefficients during the accelerometer operation, and the introduction of an additional control channel to the feedback loop. Main Results. The proposed methods were studied experimentally on a prototype quartz pendulum accelerometer with a digital feedback amplifier and a measuring range of ±50 g. The studies were carried out under the effects of vibration actions: broadband random vibration in the frequency range from 20 to 2000 Hz, (RMS deviation of the vibration acceleration amplitude of 8 g) and sinusoidal vibration in the frequency range from 20 to 2000 Hz (vibration acceleration amplitude of 10 g) along the sensitivity axis. The efficiency of the methods was estimated by the value of device vibration error — the difference between the averaged value of the device readings before vibration and the averaged value of the readings during the period of vibration. It was experimentally established that the best solution is to combine a wide bandwidth of the device with an additional control channel in the feedback loop, that reduces the accelerometer vibration error by an order of magnitude. Practical Relevance. The proposed methods increase the vibration resistance of a quartz pendulum accelerometer by applying original algorithms in the digital amplifier controller program, that makes it possible to put to use such accelerometers in objects susceptible to vibration while eliminating the need to introduce physical design modifications or additional damping measures.

Spatiotemporal phase-shifting method for accurate phase analysis of fringe pattern

High accurate phase analysis of waveforms as fringe patterns is essential for a wide range of scientific and engineering disciplines. However, precise phase analysis under extremely low signal-to-noise conditions is a challenging task for conventional phase-shifting methods. Here, a novel accurate phase recovering technique, called the spatiotemporal phase-shifting method (ST-PSM), is developed to measure the phase information robustly by utilizing two-dimensional intensity data in spatial- and temporal-domains simultaneously. Our simulation results indicated that ST-PSM had strong tolerance to random noise, and a self-neutralizing function to eliminate the periodical phase error due to the nonlinearity of detector, intensity saturation, vibration or phase-shifting error. The effectiveness was demonstrated experimentally from a non-contact shape measurement in fringe projection profilometry under extreme underexposure and overexposure recording conditions. Furthermore, by incorporating modern GPU parallel computing technology, a 4-step phase-shifted fringe pattern with 8 K image size can be calculated within one second. Due to its robustness and high accuracy with a fast calculation, therefore, we believe this technique has a significant impact on a variety of research and scientific fields.

Evaluation method of ensquared energy based on dynamic factors in gene sequencing system

In a gene sequencing system, ensquared energy is an important parameter for base-calling software. Nevertheless, the displacement between wafer and camera, which is caused by vibration and position error of the wafer stage while photographing, will decrease the image quality and further influence the ensquared energy. Our study established the relationship model between the dynamic factors and ensquared energy. Several experiments were carried out on the sequencing platform. The results revealed that the ensquared energy has a linear relationship with the location standard deviation of dynamic errors. In the sequencing platform described, if the ensquared energy value required is larger than 65%, the location standard deviation should be controlled below 140 nm. Furthermore, the ensquared energy calculated by a DNA nanoballs image is accordant with the conclusion in the meantime. The performance parameters of the wafer stage and vibration suppression could be drawn up reasonably.

Analysis of aerostatic spindle radial vibration error based on microscale nonlinear dynamic characteristics

This paper presents a method of predicting the radial rotary error of an aerostatic spindle based on the microscale-effect to investigate the influence of gas film fluctuation on the rotation accuracy of the aerostatic spindle. First, the gas bearing of the spindle is simplified as a spring-damping system with two degrees of freedom perpendicular to each other. Additionally, the aerostatic spindle bearing-rotor system is established by considering the forced vibration and deflection vibration of the rotor. Subsequently, the microscale-effect is introduced into the dynamic model of the gas film flow, and the dynamic Reynolds equation of the gas film is established in the microscale. Moreover, the nonlinear dynamic stiffness and dynamic damping coefficient are obtained by the perturbation method. The nonlinear dynamic parameters in the microscale are introduced into the dynamic model of the bearing-rotor system and all the vibration errors are obtained. By comparison with the conventional case, it is found that the spindle gyration error increased and that the response delay occurred when the microscale-effect is considered. Moreover, the influence of the supply pressure and speed on the vibration of the spindle is also analyzed. An experiment measuring the spindle rotation error is carried out. The experimental results reveal that the prediction method of the nonlinear spindle rotation error in the microscale is more accurate, and that the errors are 5.8% and 9.6%.

A robust control approach for high-speed nanopositioning applications

In this paper, a robust controller for the positioning of a piezoelectric tube scanner (PTS) used in an atomic force microscope (AFM) is proposed. A minimax linear quadratic Gaussian (LQG) controller is designed based on an uncertain system model which is constructed by measuring modeling error between the measured and model frequency response. This controller is robust against uncertainties introduced as a result of spillover dynamics of the scanner at frequencies higher than the first resonance frequency (900 Hz) of the scanner and the variation of plant transfer function due to temperature, humidity, and duration of operation. The proposed controller is applied to the PTS in the AFM used in the experiments to evaluate the performance of the proposed method. It is observed that the proposed scheme provides up to 12 dB closed-loop damping of the resonant mode to track the reference triangular signal. The robust performance of the proposed controller has been investigated for 0–1.96 g sample mass variation. A high positioning accuracy up to 125 Hz frequency is achieved by reducing scanner's vibration and tracking error. Higher-quality imaging up to 125 Hz scanning frequency is achieved compared to the existing PI controller and some other existing methods. This control technique may be applied to control vibration for the systems with changing frequency response due to uncertainties, such as vibration control of disc-drive system.

Development of an Al-load-cell-based wireless ringer's solution monitoring and alarm system: insight into vibrational error correction.

In this study, we developed an aluminum-load-cell-based wireless Ringer's solution monitoring and alarm (WRMA) system. The Al load cell was designed with a rectangular shape, and the load was concentrated in the lower beam part of the load cell because of the anisotropic thickness. From the static analysis, we identified the appropriate location for a Wheatstone bridge circuit consisting of four strain gauges. In addition, the modal and harmonic analyses showed that the vibrational frequencies of the hospital environment do not seriously interfere with the output voltage of the Al load cell. However, random vibrations generated by the movement of the WRMA system on various surfaces severely increase the standard deviation of the measured solution weight by ± 10g or more. Such vibrational error is too large because the average weight of Ringer's solution is 30-40g at the time of replacing Ringer's solution. Thus, this error could be confusing for nurses and result in mistakes in the timely replacement of the Ringer's solution. However, the standard deviation of the measured weight was dramatically reduced to ± 3g or less by using the vibration correction algorithm developed in the present study.

Possible low-energy isomers of OHn(H2O)4 (n = 0, ±1) clusters via the particle swarm optimization algorithm: An ab initio study

The possible low-energy structures of the anionic, neutral, and cationic water clusters OHn(H2O)4 (n = 0, ±1) were investigated using the particle swarm optimization algorithm together with ab initio calculations. Geometry optimization and vibrational analysis for possible low-lying water clusters were conducted at the MP2/aug-cc-pVDZ level and further verified at the CCSD(T)/aug-cc-pVTZ level. The results revealed obvious structural differences between the OH+(H2O)4, OH(H2O)4, and OH−(H2O)4 clusters. We found that correcting for the zero-point vibrational energies and basis set superposition error exerted a substantial influence on the order of relative energies for the OH−(H2O)4 and OH+(H2O)4 clusters. Topological analysis revealed that both the number and strength of hydrogen bonds were greater for the OH−(H2O)4 cluster compared with the OH+(H2O)4 and OH(H2O)4 clusters. The highest occupied molecular orbitals (HOMOs) of the anionic OH−(H2O)4 cluster were mainly located on the OH− ion and the HOMO-1s and HOMO-2s levels were mainly located on the H2O molecules, whereas in the neutral OH(H2O)4 and cationic OH+(H2O)4 clusters, the singly occupied molecular orbitals mainly originated from the water molecules.

Trajectory planning of multi-degree-of-freedom robot with coupling effect

For a multi-degree-of-freedom (MDOF) robot with flexible components, vibration errors can easily occur during operation. Thus, the position of the end effector inevitably deviates from its desired value and causes failure of the precise trajectory tracking task. To solve this problem, an MDOF KUKA robot is introduced in the present study. We propose a new methodology to investigate the dynamic coupling effect and trajectory planning for the robot. The dynamic coupling effect index is defined for the first time, thereby providing a theoretical basis for the trajectory planning. Moreover, a new trajectory plan is adopted to reduce the vibration errors caused by the coupling effect in the Cartesian coordinate and joint coordinate systems. The advantages of the proposed methodology in improving accuracy and stability are validated by experiments. In addition, the chaos phenomenon is observed, which is the focus of our future study.

Stretching of cis-formic acid: warm-up and cool-down as molecular work-out.

A new technique to rotationally simplify and Raman-probe conformationally and vibrationally excited small molecules is applied to the cis-trans isomerism of formic acid. It quintuples the previously available gas phase vibrational data base on this excited form of a strongly anharmonic planar molecule despite its limited spectral resolution. The newly determined cis-formic acid fundamentals allow for a balanced vibrational benchmark on both rotamers of formic acid. Assuming the adequacy of vibrational perturbation theory, it reveals weaknesses of standard methods for these systems like B3LYP-D3(BJ)/aVQZ VPT2 or PBE0-D3(BJ)/aVQZ VPT2. The functionals ωB97-XD and M06-2X additionally suffer from severe integration grid size and symmetry dependencies. The vibrational benchmark suggests B2PLYP-D3(BJ)/aVQZ VPT2 and MP2/aVQZ VPT2 as partially competitive and in any case efficient alternatives to computationally demanding coupled cluster vibrational configuration interaction calculations. Whether this is due to fortuitous compensation between electronic structure and vibrational perturbation error remains to be explored.

Determination of Vibrational Displacement Measurement Error Based on the Blurring Analysis of a Round Mark Image

Abstract The relevance and nature of a new technology for measurement of vibrational displacement of a material point through normal toward the object plane are stated in the article. This technology provides registration and processing of images of a round mark or a matrix of round marks, which are applied to the surface of a control object. A measuring signal here is the module of radius increment of the round mark image at vibrational blurring of this image. The method for calculation of the given error of measurements, as a function of a number of pixels of the round mark image, has been developed and proven in the present research. The results of pilot studies are given. Linearity of transformation of the measured size into a measuring signal has been proven. The conditions of a technical compromise between the field of view area of a recording device during distribution measurement of vibrational displacements along the surface of a control object, and the accuracy of this measurement are determined. The results are illustrated with numerical examples of calculations of the given error of measurements in the set field of view and the one at the given maximum set error of measurements.

Особенности работы системы регулировки периметра резонатора и вибрационная ошибка зеемановского лазерного гироскопа на 50%-ной смеси изотопов неона

Особенности работы системы регулировки периметра резонатора и вибрационная ошибка зеемановского лазерного гироскопа на 50%-ной смеси изотопов неона

An Accurate and Efficient Vision Measurement Approach for Railway Catenary Geometry Parameters

The geometry status of electric railway catenary is critical to the stability of railway power supplying. An accurate and efficient vision measurement approach for railway catenary geometry parameters (CGPs) is proposed. An image-based system using a binocular vision component composed of two line scan cameras is first described and analyzed, and then a calibration method for the vision component based on 1-D target combining with 1-D displacement platform is investigated. When the onsite inspection is performed by the test train, there are multiple degree of freedom vibrations created by onsite irregularities of railway line. The detection accuracy of CGPs is inevitably degraded due to the vibrations on the results during running. A compensation method to reduce the vibration errors is presented. Experiments carried out in real-life detections validate the effectiveness and efficiency of the proposed system.

CHF3…H2O complex revisited: a matrix isolation and ab initio study

The structural and spectroscopic features of the CHF3…H2O complex have been investigated using high-level ab initio calculations and IR matrix isolation spectroscopy. In contrast to previous findings, the computations at the CCSD(T)/L3a_3 and MP2/L3a_3 levels of theory revealed only one structure of the complex stabilized by two C-H…O and O-H…F hydrogen bonds. The interaction energy extrapolated to a complete basis set with ZPVE and BSSE corrections is 2.73 kcal/mol at the CCSD(T) level, taking into account the zero-point vibrational energy (ZPVE) and basis set superposition error (BSSE) corrections. According to Bader’s analysis, complex exhibits a cyclic structure, which confirms the existence of ring critical point as well as bond critical points in the system. The calculated complexation-induced shifts of the fluoroform fundamentals are in good agreement with the matrix isolation results. In addition to previously reported IR absorptions of the complex, the feature corresponding to the C-F bending mode of CHF3…H2O was first observed, in good correlation with the computational predictions.

Convolutional neural network for gear fault diagnosis based on signal segmentation approach

In the gear fault diagnostics, conventional methods have largely depended on the complicated signal processing and feature extraction skills, which are often cumbersome for engineers to implement easily. Recently, the convolutional neural networks, which is a kind of deep learning techniques, have found increased success in this field by taking advantage of minimal engagement of signal processing and automated features extraction for the fault diagnosis. In the previous studies, however, the accuracy of the method was often assessed by means of cross-validation from the data sets at the same faulted tooth, which may not be the case in the real gear, since the fault may appear at different teeth from the training. This article proposes a convolutional neural network method based on the signal segmentation to solve this problem, which is to divide the original signal into those at each tooth of the gear. The effectiveness of the method is validated by the data made from the gearbox test rig, in which the vibration and transmission errors are measured, respectively. The training and test data sets are prepared at different fault locations. The performances of the convolutional neural network with signal segmentation are compared and discussed with those by the ordinary convolutional neural network without segmentation. As a whole, the results with the signal segmentation suggest that the fault can be successfully identified even when the fault location in the test is different from that of the training, which provides great feasibility toward the real applications.