Optics: measuring and testing – By polarized light examination – With light attenuation
Patent
1996-05-30
1998-02-24
Evans, F. L.
Optics: measuring and testing
By polarized light examination
With light attenuation
G01B 1100
Patent
active
057216185
DESCRIPTION:
BRIEF SUMMARY
FIELD OF THE INVENTION
The present invention relates to measuring apparatus for measuring the dimensions of a large object with the aid of a narrow optical measuring beam directed onto a number of measuring points.
BACKGROUND OF THE INVENTION
The measurements of vehicle chassis are determined by means of methods in which a measuring unit which is moveable along a measuring rail is caused to direct a laser measuring beam onto measuring points on the vehicle chassis. The position of the unit along a vertical scale on the measuring rail is read-off against each measuring point on the chassis. This measurement value is fed into a memory store and is subsequently processed in a computer, for instance a personal computer or a minicomputer having sufficient data processing capacity to make the calculations required. The measurement values are computer processed and presented as absolute values together with the extent to which these values deviate from a corresponding values obtained when measuring against a standard vehicle of the actual model concerned. Consequently, data related to different makes or models of cars are available for loading into the data system used or have already been stored in the fixed memories connected to the computer system. U.S. Pat. No. 4,556,322 describes an arrangement for taking such measurements from solely one measuring rail placed adjacent the car or vehicle to be measured. U.S. Pat. No. 4,492,471 describes a simplified calibration of the system. However, the problem with the known methods is that it is not possible to also measure vertically (i.e. along a Z-axis) quickly and automatically. Manual calibrations, installations and measuring processes take a long time to effectuate and require extensive knowledge of the measuring system used.
SUMMARY OF THE INVENTION
The main object of the invention is to provide a method which will enable large objects, for instance a car chassis, to be measured fully automatically.
Another object of the invention is to provide a method which requires no special installation and calibration of the measuring apparatus in relation to the object to be measured.
Still another object of the invention is to provide a method which enables an object to be measured automatically in three dimensions.
Still another object of the invention is to provide a method which has good penetrating ability at different measuring points when measuring from a measuring rail, i.e. it shall be possible to reach all vehicles measuring points with a measuring beam from the measuring rail.
BRIEF DESCRIPTION OF THE DRAWINGS
The invention will now be described in more detail with reference to the accompanying drawings, in which
FIG. 1 illustrates a carriage which moves along a measuring rail and which includes a first embodiment of a measuring system in accordance with the present invention;
FIGS. 2-9 illustrate different embodiments of a reflector device placed at a measuring point;
FIG. 10 illustrates one embodiment of the pattern of movement of a measuring beam directed onto the object to be measured;
FIG. 11A illustrates schematically a carriage comprising a second embodiment of a measuring arrangement according to the invention;
FIG. 11B illustrates schematically a side view of an embodiment of the mirror device 171 in FIG. 11A in enlarged scale; and
FIG. 12 is a block schematic of one embodiment of a calculation circuit used in accordance with the invention.
DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS OF THE INVENTION
FIG. 1 illustrates a carriage 1 which is movable along a measuring rail 2 which functions as a measuring path. This measuring rail is intended to be placed adjacent an object to be measured, for instance a car. The object to be measured is provided with measuring devices 3-8 by means of which the impingement of a light beam, preferably from a laser in accordance with the invention, on a measuring point can be indicated automatically, such impingement being referred to as a "hit" at times. The measuring devices may either have at least one
REFERENCES:
patent: 4492471 (1985-01-01), Wiklund
patent: 4556322 (1985-12-01), Wickman et al.
patent: 4997283 (1991-03-01), Danielson et al.
patent: 5251013 (1993-10-01), Danielson et al.
Dataliner AB
Evans F. L.
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