Browsing by Subject "Table lookup"

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    Adaptive correction and look-up table based interpolation of quadrature encoder signals
    (ASME, 2012-10) Ulu, Erva; Geçer-Ulu, Nurcan; Çakmakçı, Melih
    This paper presents a new method to increase the available measurement resolution of quadrature encoder signals. The proposed method features an adaptive signal correction phase and an interpolation phase. Typical imperfections in the encoder signals including amplitude difference, mean offsets and quadrature phase shift errors are corrected using recursive least squares with exponential forgetting and resetting. Interpolation of the corrected signals are accomplished by a quick access look-up table formed offline to satisfy a linear mapping from available sinusoidal signals to higher order sinusoids. The position information can be derived from the conversion of the high-order sinusoids to binary pulses. With the presented method, 10nm resolution is achieved with an encoder having 1μm of original resolution. Further increase in resolution can also be satisfied with minimizing electrical noises. Experiment results demonstrating the effectiveness of the proposed method for a single axis and two axis slider systems are given. Copyright © 2012 by ASME.
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    Application of signal-processing techniques to dipole excitations in the finite-difference time-domain method
    (Taylor & Francis, 2002) Oğuz, U.; Gürel, Levent
    The applications of discrete-time signal-processing techniques, such as windowing and filtering for the purpose of implementing accurate excitation schemes in the finite-difference time-domain (FDTD) method are demonstrated. The effects of smoothing windows of various lengths and digital lowpass filters of various bandwidths and characteristics are investigated on finite-source excitations of the FDTD computational domain. Both single-frequency sinusoidal signals and multifrequency arbitrary signals are considered.
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    Zero-free-parameter modeling approach to predict the voltage of batteries of different chemistries and supercapacitors under arbitrary load
    (Electrochemical Society, Inc., 2017) Özdemir, E.; Uzundal, C. B.; Ulgut, B.
    Performance modeling of electrochemical energy storage systems is gathering increasingly higher attention in recent years. With the ever increasing power demand of mobile applications, predicting voltage behavior under different load profiles is of utmost importance for communications, automotive and consumer electronics. The ideal modelling approach needs not only to accurately predict the response of the battery, but also be robust, easy to implement and have low computational complexity. We will present a new algorithm that is algebraically straightforward, that has no adjustable parameters and that can accurately predict the voltage response of batteries and supercapacitors. The approach works well in a variety of discharge profiles ranging from simple long DC discharge/charge profiles to pulse schemes based on drive schedules published by regulatory bodies. Our approach is based on Electrochemical Impedance Spectroscopy measurements done on the system to be predicted. The spectrum is used in the frequency domain without any further processing to predict the fast moving portion of the voltage in the frequency domain. DC response is added in through a straightforward lookup table. This widely applicable approach can predict the voltage of with less than 1% error, without any adjustable parameters to a large variety of discharge profiles.