38 results about "Discretization error" patented technology

A method is provided for designing a mask that includes the use of a pixel-based simulation of a lithographic process model, in which test structures are designed for determining numerical and discretization errors associated with the pixel grid as opposed to other model inaccuracies. The test structure has a plurality of rows of the same sequence of features, but each row is offset from other rows along an x-direction by a multiple of a minimum step size, such as used in modifying masks during optical proximity correction. The images for each row are simulated with a lithographic model that uses the selected pixel-grid size and the differences between row images are compared. If the differences between rows exceed or violate a predetermined criterion, the pixel grid size may be modified to minimize discretization and / or numerical errors due to the choice of pixel grid size.

A feedforward control system using a polynomial formula not affected by discretization error is realized in a magnetic disk drive. In one embodiment, the magnetic disk drive is intended to move a head for performing at least one of recording and playback to and from a magnetic recording medium to a target position. The feedforward input has a seek control system computed by a polynominal formula of a time function. The coefficients of the polynomial formula have been derived from boundary conditions including the characteristics of a zero-order hold.

A digital filter is designed by combining unit filters (L10′, H10′) having a predetermined asymmetric numerical sequence as filter coefficients (H1 to H3). Thus, it is possible to automatically obtain a desired digital filter coefficient only by combining the unit filter. Moreover, a symmetric numerical sequence {−1, 0, 9, 16, 9, 0, −1} / 32 is divided at the center into two parts and one of them is used as the asymmetric filter coefficients (H1 to H3). This reduces the number of taps required for the digital filter designed, eliminates use of a window function, and prevents generation of a discretization error in the filter characteristic obtained.

The invention discloses a method for observing the flux linkage of an induction motor rotor, which relates to the technical field of motor control. The invention aims to solve the problem that the discretization error is large and the accuracy of the flux linkage observation is low when the conventional flux linkage observer is discretized. The method for observing the rotor flux linkage of an induction motor according to the present invention collects the stator current of the induction motor, establishes a rotor flux observer, uses the improved Euler method to discretize the rotor flux observer and obtains observation values, the described The observed values ​​are used to control the induction motor, and the improved Euler method is a combined discretization method of the forward Euler method and the trapezoidal discretization method. The invention is suitable for the observation part of the rotor flux linkage in the induction motor control, so as to improve the accuracy of the flux linkage observation.

The invention relates to a method and an electric motor arrangement for determining a corrected rotational speed signal. In one step of the method, a periodic rotational angle signal is detected which has a periodic rotational angle error which is dependent on the rotational angle. Converting the rotation angle signal into a digital original speed signal (16), due to the rotation angle error, the digital original speed signal has an interference ripple, and the cycle duration of the interference ripple corresponds to the cycle duration of the rotation angle error . The digital raw rotational speed signal (16) comprises a plurality of sampled values ​​(07), which are spaced apart in time by the duration of the sampling period, the half-period duration of the disturbance ripple of the raw rotational speed signal (16) being determined. Averaging at least one pair of sampling values ​​(07) of the original rotational speed signal (16), the time interval of the at least one pair of sampling values ​​aside from the time discretization error is the interference ripple of the original rotational speed signal (16) The known half-cycle duration. The average value is obtained by averaging. A correction value is formed that is dependent on the sampling period duration and the frequency of the disturbance ripple to account for discretization errors. The corrected rotational speed signal is formed from the difference between the mean value and the corrected value. The correction signal varies in a sawtooth fashion as a function of the difference between the sampling period duration and the period duration of the disturbance ripple, the maximum amplitude of the correction signal also increasing with increasing frequency of the disturbance ripple.

The invention discloses a cycloidal gear tooth curve variable step size discretization method, which comprises the following steps of S1, setting a cycloidal gear tooth curve parameter; S2, deriving out a cycloidal gear tooth curve equation; S3, deriving out a formula of the curvature radius Rho of the practical tooth curve of a cycloidal gear; S4, deriving out an equation of phi relevant to a pressure angle alpha; S5, deriving out an inflexion equation of the cycloidal gear tooth curve; S6, giving the curve linear interpolation initial step size discretization method. The discretization errors and given errors are compared for automatically regulating the closing step size, so that the maximum step size smaller than the closing errors can be obtained; on the premise of meeting the precision requirements, the number of cutting feeding times is reduced; the processing efficiency is improved. The cycloidal gear tooth curve variable step size discretization method provided by the invention has the advantage that the good integral index is realized in the aspects of closing precision, discretization efficiency and calculation speed.