Optics: measuring and testing – Position or displacement – Position transverse to viewing axis
Reexamination Certificate
2001-12-18
2004-05-04
Font, Frank G. (Department: 2877)
Optics: measuring and testing
Position or displacement
Position transverse to viewing axis
C356S614000
Reexamination Certificate
active
06731392
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to a marker used for measuring displacements of a moving object, and more particularly, to a marker used for measuring displacement of an object moving on a plane by using a line scan camera and a method for measuring the displacements of the moving object.
2. Description of the Prior Art
Generally, displacements of a moving object are measured in various methods. For example, there is a method of measuring the displacements of the moving object from two-dimensional image data on the moving object which has been continuously photographed by a two-dimensional image camera.
However, when the displacements of the moving object are measured by the two-dimensional image camera, a large volume of the two-dimensional data of the moving object is obtained. Thus, there is a shortcoming in that a measurement speed is slow. As a result, in a case where the object moves at a high speed or any impact is exerted on the object, there is limitation that the displacements of the object cannot be measured. On the other hand, the line scan camera employed in the present invention photographs one-dimensional linear images which are composed of one dimensional array of pixels. Thus, although the line scan camera is restrictive as compared with the two-dimensional image camera when obtaining the image data, it has an advantage that the image data can be obtained at a very high speed.
SUMMARY OF THE INVENTION
Accordingly, the present invention is contemplated to solve the aforementioned problem produced when a conventional two-dimensional image camera measures displacement of a moving object. An object of the present invention is to provide a marker used for measuring displacement of an object moving on a plane and a method for measuring the displacement of the moving object by using a line scan camera capable of measuring a two-dimensional planar motion of the object from one-dimensional linear image data of the object.
Another object of the present invention is to provide a marker used for measuring displacement of an object moving on a plane and a method for measuring the displacement of the moving object by using a line scan camera capable of precisely measuring an object which moves at a high speed or on which any impact is exerted.
According to an aspect of the present invention for achieving the above objects, there is provided a marker used for measuring displacement of a moving object by using a line scan camera, comprising a plurality of repeatedly arranged figures having the same size and shape, each of the figures being measurable by means of the line scan camera and asymmetric with respect to a direction of a scan line of the line scan camera. Preferably, each of the figures may be a right-angled triangle of which base is a horizontal line.
According to another aspect of the present invention, there is provided a method for measuring displacement of a moving object by using a line scan camera, comprising the steps of fixedly attaching a displacement measurement marker to a surface of the moving object, the marker comprising a plurality of repeatedly arranged figures having the same size and shape, each of the figures being measurable by means of the line scan camera and asymmetric with respect to a direction of a scan line of the line scan camera; setting coordinate systems of the displacement measurement marker, and obtaining general functional formulas for two lines of an n-th (n= . . . , −3, −2, −1, 0, 1, 2, 3, . . . ) figure of the displacement measurement marker at time t=0; obtaining general equations for intersection points between the scan line and the n-th two lines; obtaining two general distance ratios of the intersection points for an arbitrary integer of n from the general equation for the two intersection points; obtaining a general functional formula for the scan line having a gradient a and a y-intercept b for expressing as a general equation for the arbitrary integer of n from the two distance ratios; continuously photographing the displacement measurement marker moving together with the object by the line scan camera; obtaining two actual distance ratios from images photographed by the line scan camera; substituting the two actual distance ratios obtained from the images into the general equation having the gradient a and the y-intercept b so as to obtain an actual functional formula for the scan line; obtaining a central coordinate P
C
of the scan line by means of the actual functional formula for the scan line; and obtaining a relative displacement and a rotational angle between central coordinates of the scan line obtained for arbitrary time between t=0 and t=t.
REFERENCES:
patent: 4550250 (1985-10-01), Mueller et al.
patent: 5598270 (1997-01-01), Meisser et al.
Chung Sam Yong
Han Song Soo
Kim Seok Ho
Lee Sang Heon
Lim Mee Seub
Lowe Hauptman & Gilman & Berner LLP
Punnoose Roy M.
Samsung Corporation
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