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Didier Remond - One of the best experts on this subject based on the ideXlab platform.

  • Non-intrusive rattle noise detection in non-stationary conditions by an angle/time cyclostationary approach
    Journal of Sound and Vibration, 2016
    Co-Authors: Sophie Baudin, Didier Remond, Jerome Antoni, Olivier Sauvage
    Abstract:

    This work proposes an original non-intrusive approach to detect and quantify rattle noise in automotive gearboxes operating under non-stationary conditions by means of vibration or instantaneous angular speed measurements. Rattle noise is produced by vibro impacts between teeth of unloaded gears excited by the engine acyclism. It appears during acceleration or deceleration phases and its detection requires the analysis of non-stationary signals. In order to take advantage of the repetitive nature of the impacts, an angle/time cyclostationary approach is introduced. Rattle noise is thus characterized through the angle/time duality: the cyclic frequency expressed in events per revolution is directly linked to the periodicity of the impacts while their frequency content is expressed in Hertz. The proposed detection method uses an order/frequency spectral coherence and may be applied either on vibration signals or instantaneous angular speed signals. For validation purposes, a specific instrumentation of a gearbox is set up. The relative speed of the unloaded meshing gears is observed by means of Optical Encoders to directly detect the instants of impact which then serve as a basis for validation of the non-intrusive detection method proposed in this paper.

  • Detection of rattle noise with Optical Encoders in run-up conditions
    2014
    Co-Authors: Sophie Baudin, Didier Remond, Jerome Antoni, Olivier Sauvage
    Abstract:

    This work proposes an original approach to detect rattle noise of automotive gearbox under non-stationary conditions. Rattle noise is produced by vibro impacts between teeth of unloaded gears and principally caused by the engine acyclism. A test bench with a universal joint is used to generate acyclism and to permit the appearance of rattle noise during speed ramp. One Optical encoder is placed inside the gearbox to access the instantaneous angular speed of one loose gear and two other Encoders are placed at the end of the primary and secondary shafts outside the gearbox. First of all the relative speed of the unloaded meshing gears is observed to directly detect the instants of impact. These results are compared with an original method of detection based on an angle/time cyclostationary approach. The advantage is to keep the angle/time duality to characterize this phenomenon: the cyclic frequency expressed in events per revolution is indeed directly linked to the periodicity of the impacts while their nature is linked to the bandwidth expressed in Hertz.

  • Detection of gearbox rattle noise in run-up conditions
    2014
    Co-Authors: Sophie Baudin, Didier Remond, Jerome Antoni, Olivier Sauvage
    Abstract:

    This work proposes an original approach to detect rattle noise in car gearboxes. Rattle noise is produced by vibro impacts between teeth of unloaded gears. These impacts are principally caused by the engine acyclism transmitted to the primary shaft of the gearbox after being partially filtered by the clutch. The appearance and the level of rattle noise depend, among others, on the operating conditions and more particularly on the rotation speed. The interest is then here focused on tests in run up conditions in order to scan a large panel of operating conditions. The objective of this work is to develop an efficient method to detect rattle noise in signals based on an angle-time cyclostationary approach. The results are compared to a more intrusive detection methodology exploiting signals issued from Optical Encoders.

  • Parametric Instability of an Axially Moving Belt Subjected to Multifrequency Excitations: Experiments and Analytical Validation
    Journal of Applied Mechanics, 2008
    Co-Authors: Guilhem Michon, Didier Remond, Lionel Manin, Régis Dufour, Robert Parker
    Abstract:

    This paper experimentally investigates the parametric instability of an industrial axially moving belt subjected to multifrequency excitation. Based on the equations of motion, an analytical perturbation analysis is achieved to identify instabilities. The second part deals with an experimental setup that subjects a moving belt to multifrequency parametric excitation. A data acquisition technique using Optical Encoders and based on the angular sampling method is used with success for the first time on a nonsynchronous belt transmission. Transmission error between pulleys, pulley/belt slip, and tension fluctuation are deduced from pulley rotation angle measurements. Experimental results validate the theoretical analysis. Of particular note is that the instability regions are shifted to lower frequencies than the classical ones due to the multifrequency excitation. This experiment also demonstrates nonuniform belt characteristics (longitudinal stiffness and friction coefficient) along the belt length that are unexpected sources of excitation. These variations are shown to be sources of parametric instability.

  • practical performances of high speed measurement of gear transmission error or torsional vibrations with Optical Encoders
    Measurement Science and Technology, 1998
    Co-Authors: Didier Remond
    Abstract:

    We evaluated in this paper an improved technique for measuring gear transmission error (GTE) at high speed, by using low pulse per revolution Optical Encoders. The originality of this technique lies in the fact that highly precise, completely digital measurements of torsional vibration or transmission error (TE) at high speed are achievable by the use of low-price, basic Optical components. The lengths of encoder pulses are estimated with a high-frequency timer (100 MHz): thus, it appears that the theoretical precision of this device depends only on the angular speed of shafts, not on the number of pulses per revolution of the encoder. In practice, the intrinsic encoder accuracy (namely the grating or electronic signal processing precision) directly affects precision measurements. Alternatively, the number of pulses per revolution of the encoder specifies the resolution. We examined the possibility of calibrating Encoders through using a specific test rig. The determination of corrective data assigned to each grating leads to an insignificant improvement of the precision measurement. The coherence from one revolution to another does not present any significant deterministic component. The overall precision achieved is less than 0.03 second of arc for each frequency of the power spectral density. This calibration device only gives a good assessment of eccentricity induced by mechanical mounting of Optical discs on a shaft, compared with the direct measurement on grating discs. The correlation between the two measurements is less than 3% of the magnitude of the relative eccentricity. Thus, the encoder technique seems to be a cheap and easy way to implement transmission error measurement on real mechanical systems with high precision and sufficient reliability.

Hongzhong Liu - One of the best experts on this subject based on the ideXlab platform.

  • Optimal design of a reflective diffraction grating scale with sine-trapezoidal groove for interferential Optical Encoders
    Optics and Lasers in Engineering, 2020
    Co-Authors: Liu Hui, Biao Lei, Dong Niu, Hongwen Xing, Pingping Wei, Hongzhong Liu
    Abstract:

    Abstract Interferential Optical Encoders are promising nano-positioning sensors in precision manufacturing and metrology instrumentation. As measuring standard, the quality of diffraction grating scales primarily determines the performance of the interferential Optical Encoders. In this work, the optimal design and fabrication of a reflective diffraction grating scale with sine-trapezoidal groove is performed. Firstly, the requirement for diffraction characteristics of diffraction grating scales is specified by introducing the basic principle of interferential Optical Encoders. Sequentially, the critical requirements of the diffraction grating scales are further specified by theoretically investigating the influence of groove-profile parameters (i.e. line height, groove and ridge widths) and micro-defect parameters (i.e. surface roughness and line roughness) on the diffraction characteristics of diffraction grating scales. Finally, morphological parameter optimization of a diffraction grating scale with a pitch of 4 μm is performed, and the diffraction grating scale is fabricated and characterized. The characterization results indicate that the fabricated diffraction grating scale conforms well to the optimal design, and is ideal for application in interferential Optical Encoders.

  • Electronic Interpolation Interface Based on Linear Subdivision Method for Sinusoidal Optical Encoders
    IEEE Sensors Journal, 2020
    Co-Authors: Zhao Guobo, Liu Hui, Biao Lei, Han Weiliang, Hongzhong Liu
    Abstract:

    Sinusoidal Optical Encoders are widely utilized in precision positioning systems. With the development of precision positioning systems, higher resolution is required. Electronic interpolation is a promising technique to further improve the resolution of sinusoidal Optical Encoders. In this paper, we propose an electronic interpolation interface based on linear subdivision method with better practical accuracy. Firstly, a pseudo-linearized signal based on the difference between the absolute values of sine and cosine signals is generated. Then, a compensation signal with a ratiometric form is constructed, which has a better robustness to the non-ideal input signals. Finally, a nearly perfect linear output signal is obtained by combining these two signals. Thus, the displacement can be linearly determined without LUTs. It is shown that the theoretical nonlinear error of the proposed method is below 0.08° over a signal period of 360°, which corresponds to a theoretical interpolation error of $0.018~\mu \text{m}$ for sinusoidal Optical Encoders with a pitch of $80~\mu \text{m}$ . Moreover, theoretical analysis and simulation results indicate that the proposed method offers a better practical accuracy. In the experiment, the proposed electronic interpolation interface is developed in a field-programmable gate array (FPGA), and experiments are carried out to evaluate its performance. Both the theoretical and experiment results verify its effectiveness.

  • Development of a reflective Optical encoder with submicron accuracy
    Optics Communications, 2018
    Co-Authors: Hongzhong Liu, Yaowen Ban, Yongsheng Shi, Lei Yin
    Abstract:

    Abstract Signal distortion is a key issue that limits the measurement resolution and accuracy of Optical Encoders. In this paper, an Optical encoder based on generalized grating imaging using a two-dimensional index grating is presented. The general expression of intensity distribution for generalized grating imaging including the relative displacement between the scale grating and the reading head is derived, and the formation of the signal distortion of the Optical encoder is analyzed. Then, a two-dimensional index grating, which consists of multiple grating tracks with defined offsets, is proposed to suppress the dominant third and fifth order harmonic signals. The operating principle of the two-dimensional index grating is explained in detail and a reflective Optical encoder is developed. In the experiment, approximately ideal Lissajous figure of the encoder signals is obtained. Fourier analysis of the encoder signals shows that both the third and fifth order harmonic distortions are below 0.6%. Experimental results show that the interpolation error of the Optical encoder is within ± 0 . 18 μ m, and the accuracy is better than ± 0 . 3 μ m over 255 mm travel range with a maximum variation of 0.136 μ m.

  • Ratiometric-Linearization-Based High-Precision Electronic Interpolator for Sinusoidal Optical Encoders
    IEEE Transactions on Industrial Electronics, 2018
    Co-Authors: Hongzhong Liu, Biao Lei, Yongsheng Shi, Yang Wang, Lei Yin
    Abstract:

    Electronic interpolation is the key technology for further improving the measurement resolution of Optical Encoders. In this paper, an electronic interpolator based on the ratiometric linearization conversion method is presented. The proposed method converts the sinusoidal encoder signals into a nearly perfectly linear output signal through mathematical manipulation that only involves basic operations of addition, subtraction, multiplication, and division. Thus, the displacement can be precisely determined using a simple linear equation. Furthermore, quadrature interpolation pulses are also generated from the linear output signal by using the amplitude subdivision method. Since the linearization procedure is based on the ratiometric operation, interpolation accuracy is independent of amplitude fluctuation of the encoder signals. Theoretical analysis shows that the nonlinear error of the proposed interpolator is below ±0.0034 rad over a signal period of 2 π rad, which corresponds to an interpolation error of ±0.0108  μ m for a linear Optical encoder with a pitch of 20  μ m. In the experiment, the proposed strategy is successfully implemented within a field programmable gate array, and applied to a 20  μ m-pitch Optical encoder. Experiments are performed to demonstrate the effectiveness of the proposed method.

  • fabrication of high edge definition steel tape gratings for Optical Encoders
    Review of Scientific Instruments, 2017
    Co-Authors: Hongzhong Liu, Jiawei Yan, Yaowen Ban, Shanjin Fan, Yongsheng Shi, Lei Yin
    Abstract:

    High edge definition of a scale grating is the basic prerequisite for high measurement accuracy of Optical Encoders. This paper presents a novel fabrication method of steel tape gratings using graphene oxide nanoparticles as anti-reflective grating strips. Roll-to-roll nanoimprint lithography is adopted to manufacture the steel tape with hydrophobic and hydrophilic pattern arrays. Self-assembly technology is employed to obtain anti-reflective grating strips by depositing the graphene oxide nanoparticles on hydrophobic regions. A thin SiO2 coating is deposited on the grating to protect the grating strips. Experimental results confirm that the proposed fabrication process enables a higher edge definition in making steel-tape gratings, and the new steel tape gratings offer better performance than conventional gratings.

Blake Hannaford - One of the best experts on this subject based on the ideXlab platform.

  • single chip velocity measurement system for incremental Optical Encoders
    IEEE Transactions on Control Systems and Technology, 1997
    Co-Authors: Pamela Bhatti, Blake Hannaford
    Abstract:

    A single-chip system is designed, implemented, tested, and analyzed for the measurement of velocity from incremental Optical Encoders with quadrature outputs. The system uses a field programmable gate array (FPGA) chip to take advantage of high flexibility and a low-cost design cycle. The device uses two counting methods: period counting for low velocities and frequency counting for high velocities to obtain high resolution measurements for a wide range of velocities with a fixed 16-b word length. Verification testing of the device was consistent with predicted error and showed that quantization errors can be made arbitrarily small by adjusting the tradeoff between velocity range and minimum resolution. This tradeoff can be adjusted by the designer by simple modifications to the basic design.

M. Artés - One of the best experts on this subject based on the ideXlab platform.

  • a new methodology for vibration error compensation of Optical Encoders
    Sensors, 2012
    Co-Authors: Jesus Lopez, M. Artés
    Abstract:

    Optical Encoders are sensors based on grating interference patterns. Tolerances inherent to the manufacturing process can induce errors in the position accuracy as the measurement signals stand apart from the ideal conditions. In case the encoder is working under vibrations, the oscillating movement of the scanning head is registered by the encoder system as a displacement, introducing an error into the counter to be added up to graduation, system and installation errors. Behavior improvement can be based on different techniques trying to compensate the error from measurement signals processing. In this work a new “ad hoc” methodology is presented to compensate the error of the encoder when is working under the influence of vibration. The methodology is based on fitting techniques to the Lissajous figure of the deteriorated measurement signals and the use of a look up table, giving as a result a compensation procedure in which a higher accuracy of the sensor is obtained.

  • Method for the evaluation of Optical Encoders performance under vibration
    Precision Engineering-journal of The International Societies for Precision Engineering and Nanotechnology, 2007
    Co-Authors: I. Alejandre, M. Artés
    Abstract:

    Optical Encoders are the preferred choice for position measurement, both linear and angular, when high accuracy is required. Their performance is widely affected by deformation, temperature and vibration. This last aspect is analysed, showing the limitations found in conventional methods of performance evaluation. The determining parameters, such as sweep type, sampling rate, trigger etc. are examined and a final diagram of measuring accuracy versus frequency is presented, where aspects as resonance effects and measuring uncertainty are identified and discussed. Experimental analyses have been made in a commercial linear Optical encoder and show that its measuring error is three times its precision, and wide areas of large measuring uncertainty are present in the frequency span. The information obtained through this method can be used to improve encoder design and mounting conditions in the machine, reducing the total error.

Lei Yin - One of the best experts on this subject based on the ideXlab platform.

  • Development of a reflective Optical encoder with submicron accuracy
    Optics Communications, 2018
    Co-Authors: Hongzhong Liu, Yaowen Ban, Yongsheng Shi, Lei Yin
    Abstract:

    Abstract Signal distortion is a key issue that limits the measurement resolution and accuracy of Optical Encoders. In this paper, an Optical encoder based on generalized grating imaging using a two-dimensional index grating is presented. The general expression of intensity distribution for generalized grating imaging including the relative displacement between the scale grating and the reading head is derived, and the formation of the signal distortion of the Optical encoder is analyzed. Then, a two-dimensional index grating, which consists of multiple grating tracks with defined offsets, is proposed to suppress the dominant third and fifth order harmonic signals. The operating principle of the two-dimensional index grating is explained in detail and a reflective Optical encoder is developed. In the experiment, approximately ideal Lissajous figure of the encoder signals is obtained. Fourier analysis of the encoder signals shows that both the third and fifth order harmonic distortions are below 0.6%. Experimental results show that the interpolation error of the Optical encoder is within ± 0 . 18 μ m, and the accuracy is better than ± 0 . 3 μ m over 255 mm travel range with a maximum variation of 0.136 μ m.

  • Ratiometric-Linearization-Based High-Precision Electronic Interpolator for Sinusoidal Optical Encoders
    IEEE Transactions on Industrial Electronics, 2018
    Co-Authors: Hongzhong Liu, Biao Lei, Yongsheng Shi, Yang Wang, Lei Yin
    Abstract:

    Electronic interpolation is the key technology for further improving the measurement resolution of Optical Encoders. In this paper, an electronic interpolator based on the ratiometric linearization conversion method is presented. The proposed method converts the sinusoidal encoder signals into a nearly perfectly linear output signal through mathematical manipulation that only involves basic operations of addition, subtraction, multiplication, and division. Thus, the displacement can be precisely determined using a simple linear equation. Furthermore, quadrature interpolation pulses are also generated from the linear output signal by using the amplitude subdivision method. Since the linearization procedure is based on the ratiometric operation, interpolation accuracy is independent of amplitude fluctuation of the encoder signals. Theoretical analysis shows that the nonlinear error of the proposed interpolator is below ±0.0034 rad over a signal period of 2 π rad, which corresponds to an interpolation error of ±0.0108  μ m for a linear Optical encoder with a pitch of 20  μ m. In the experiment, the proposed strategy is successfully implemented within a field programmable gate array, and applied to a 20  μ m-pitch Optical encoder. Experiments are performed to demonstrate the effectiveness of the proposed method.

  • fabrication of high edge definition steel tape gratings for Optical Encoders
    Review of Scientific Instruments, 2017
    Co-Authors: Hongzhong Liu, Jiawei Yan, Yaowen Ban, Shanjin Fan, Yongsheng Shi, Lei Yin
    Abstract:

    High edge definition of a scale grating is the basic prerequisite for high measurement accuracy of Optical Encoders. This paper presents a novel fabrication method of steel tape gratings using graphene oxide nanoparticles as anti-reflective grating strips. Roll-to-roll nanoimprint lithography is adopted to manufacture the steel tape with hydrophobic and hydrophilic pattern arrays. Self-assembly technology is employed to obtain anti-reflective grating strips by depositing the graphene oxide nanoparticles on hydrophobic regions. A thin SiO2 coating is deposited on the grating to protect the grating strips. Experimental results confirm that the proposed fabrication process enables a higher edge definition in making steel-tape gratings, and the new steel tape gratings offer better performance than conventional gratings.

  • multiple harmonics suppression for Optical Encoders based on generalized grating imaging
    Journal of Modern Optics, 2016
    Co-Authors: Hongzhong Liu, Yongsheng Shi, Lei Yin, Bangdao Chen
    Abstract:

    AbstractIn this work, we perform an investigation on the multiple harmonics suppression for Optical Encoders based on generalized grating imaging. We firstly analyse the formation of the harmonic distortion of the encoder signals and evaluate the interpolation errors caused by the higher harmonic signals. The result shows that the harmonic distortion of the encoder signals depends mainly on the higher harmonic components in the interference fringe. In addition, it shows that the higher harmonic signals influence the Lissajous figure of the encoder signals significantly and introduce a relatively large interpolation error. Then, conditions for eliminating the higher harmonic signals are studied, and Optical filtering methods using specially designed index grating are proposed. We explain the filtering principle in detail and present three forms of index grating for multiple harmonics suppression. In particular, we show the patterns of the index grating for eliminating the dominant third and fifth harmonics...

  • a theoretical investigation of generalized grating imaging and its application to Optical Encoders
    Optics Communications, 2015
    Co-Authors: Hongzhong Liu, Biao Lei, Shanjin Fan, Yongsheng Shi, Lei Yin
    Abstract:

    Abstract Since Optical Encoders based on generalized grating imaging are more compact and robust than conventional Moire Encoders, they are preferable to be installed in industrial systems. To some extent, the measurement resolution and accuracy are limited by harmonic distortion of the encoder signals. In this work, an analysis of the pseudoimaging formation in a system including one grating illuminated by a point light source is firstly performed using a scalar Fresnel approach. Then, we analyze an Optical encoder with a double grating configuration by considering the slits of the index grating as an array of point light source and considering the pseudoimages at the observation plane as superposition of the pseudoimages formed by each point light source. Conditions for the locations and contrast of the pseudoimages are derived. It shows that sufficient signal amplitude can be obtained at Talbot planes allowing a relative large gap tolerance. In particular, the harmonic distortion of the pseudoimages is analyzed and conditions for eliminating or suppressing the harmonic components are studied. The simulation results indicate that the n-th order harmonic component can be eliminated by setting the size of the slits of the index grating to be 2p1/n, where p1 is the period of the scale grating. Moreover, the dominant 3rd order harmonic component can also be suppressed by setting the aperture ratio of the scale grating to be 72.2%.