Displacement measuring device, method and system of a grating ruler

Abstract

The application discloses a displacement measurement device of a grating ruler, which includes an interception module, which is used to process the digital displacement signal of the grating ruler with a window function to obtain the digital displacement signal after interception; , perform a single two-by-two addition of the intercepted digital displacement signal to obtain the summed digital displacement signal; the transformation module is used to process the summed digital displacement signal by using fast Fourier transform to obtain a complex digital displacement signal ; The displacement determination module is used to determine the displacement of the grating ruler according to the complex digital displacement signal. In this application, the measurement device processes the digital displacement signal of the grating scale through the interception module, and the digital displacement signal obtained after interception is a complete periodic signal, and the phenomenon of spectral leakage is reduced, so that after the processing module, the transformation module, and the displacement determination module processing The accuracy of the displacement of the grating ruler obtained after is higher. The present application also provides a measurement method and system with the above advantages.

Description

technical field [0001] The present application relates to the technical field of photoelectric measurement, in particular to a displacement measuring device, method and system of a grating ruler. Background technique [0002] With the development of manufacturing industry, people have more and more strict requirements on the precision of mechanical movement in manufacturing industry. The grating ruler is the core component of the mechanical motion accuracy. It measures the linear motion parameters of the machine along the coordinate axis and feeds back the relevant information to the control system to ensure that the accuracy of the mechanical motion is within the required range. Incremental grating scale is to modulate the light into moiré fringes through two relative moving gratings. After counting and subdividing the moiré fringes, the displacement variation is obtained, and by setting one or more reference points on the scale grating to determine the absolute position. ...

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Problems solved by technology

[0003] In the prior art, Fourier transform is used to process the collected incremental grating signal. Although the displacement of the incremental grating can be obtained, the following two problems exist. First, only when the sampling frequency is The measured displacement is only accurate when the Fourier transform frequency interval is an integer multiple, that is, each measurement must be measured from the specified starting point, otherwise there will be "asynchronous sampling" and the measured displacement will be inaccurate. Then only correction measures can be used to correct it, but this will increase the amount of calculation; second, there is a serious spectrum leakage phenomenon in Fourier transform, which leads to a decrease in measurement accuracy, thus affecting the displacement measurement accuracy of the incremental grating ruler

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