Digitizing method

Electricity: motive power systems – Positional servo systems – Program- or pattern-controlled systems

Patent

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Details

318571, 318579, 36447403, 36447404, 36447437, 356375, 356376, G05B 1918

Patent

active

049995553

DESCRIPTION:

BRIEF SUMMARY
BACKGROUND OF THE INVENTION



Technical Field

The present invention relates to a digitizing method using a non-contact type range finder such as a laser range finder, and more particularly, to a digitizing method in which a specified profile is provided on a part of a model to obtain correction data for correcting digitizing data.


BACKGROUND ART

A digitizing method has been proposed which comprises irradiating a laser beam onto the surface of a model, measuring the distance from the model surface through detection of the reflected laser beam, and while performing a follow-up control to maintain the distance from the model surface at a constant value, reading a machine position of each axis at regular intervals of time or distance for storage in a memory.
The reflectivity of the model surface and the scattering rate of the reflected wave may vary in accordance with the material of the model used, thereby causing significant errors in measurements by a detection signal from a range finder, and thus lowering the accuracy of digitizing data. Accordingly, it is to obtain accurate digitizing data unless the materials and surface conditions of models are limited.


SUMMARY OF THE INVENTION

The object of the present invention is to solve the aforementioned problems and provide a digitizing method in which a specified profile is provided on a part of a model to obtain correction data for correcting digitizing data.
To solve the above problems, the present invention provides a digitizing method in which a distance from a surface of a model is measured and stored at regular intervals of time or distance to obtain digital profile data of the model, comprising
providing a specified profile for correction on a part of the model,
issuing a measurement command and obtaining correction data such as a distance correction coefficient, a zero point correction value, and the like from a command value and an actually measured value, by using the specified profile, before the start of digitizing, and
correcting digitizing data obtained by carrying out the digitizing, by the correction data.
Using the specified profile provided on a part of the model before carrying out the digitizing, a constant distance command is issued and correction data is obtained from the command value and actual measurement data.
Therefore, the correction data is obtained based on the material and surface condition of the actual model, it is possible to accurately correct the digitizing data.


BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a block diagram of a device for carrying out a digitizing method according to the present invention;
FIG. 2 is a diagram showing a specified profile provided on a model;
FIG. 3(a) is a diagram showing an example of the specified profile;
FIG. 3(b) is a diagram showing another example of the specified profile;
FIG. 4 is a diagram for illustrating how correction data is obtained with the specified profile of FIG. 3(a);
FIG. 5 (a) and FIG. 5(b) are flowcharts for obtaining correction and data; and
FIG. 6 is a flowchart of a digitizing method according to one embodiment of the present invention.


DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT

An embodiment of the present invention will now be described with reference to the drawings.
FIG. 1 is a block diagram of a device for carrying out a digitizing data correction method according to the present invention. In FIG. 1, numeral 1 denotes a processor for global control, 2 denotes a timer for informing the processor 1 of an elapse of time, and 3 denotes a memory including a ROM storing a control program, a RAM for storing various parameters, data, etc., and the like An input/output signal interface (I/O) 4 carries out an exchange of input/output signal with an outside source, and an AD converter 5 converts an analog signal from a range finder 10 into a digital signal. Denoted at 6x, 6y, and 6z are DA converters for X, Y, and Z axes, respectively, for converting digital command values written by the processor 1 into analog values as outputs, and 7x, 7y, and 7z denote

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