Boots – shoes – and leggings
Patent
1989-02-08
1990-10-09
Ruggiero, Joseph
Boots, shoes, and leggings
318578, G06F 1546
Patent
active
049624601
DESCRIPTION:
BRIEF SUMMARY
BACKGROUND OF THE INVENTION
(1) Field of the Invention
This invention relates to a digitizing apparatus in which the surface of a model is traced by a probe which measures distance contactlessly, thereby forming digitizing data along the profiling path.
(2) Description of the Related Art
In ordinary tracer control, a stylus is moved while in contact with the surface of a model. Displacement quantities .epsilon.x, .epsilon.y, .epsilon.z along respective axes, which depend upon the tracing path on the model surface, are detected from a tracer head. In a tracer control apparatus, the displacement quantities .epsilon.x, .epsilon.y, .epsilon.z along the respective axes are combined into a vector and the direction of a normal to the model surface is computed to form profiling data. When machining is subsequently performed based on the digitizing data, offset values conforming to the axial components of the normal vector are decided and a difference between stylus diameter and cutter diameter is corrected by a three-dimensional correction.
In digitizing based on this conventional contact profiling system, the direction of displacement does not accurately reflect the normal line direction of the model surface due to friction between the stylus and model. It is difficult to form accurate digitizing data because of disturbance caused by roughness of the model surface. In addition, due to the inaccurate normal vector, the original model shape cannot be reproduced at the time of machining even if cutter diameter is compensated for in three dimensions.
SUMMARY OF THE INVENTION
The present invention has been devised in order to solve the foregoing problems. Its object is to provide a digitizing apparatus in which the digitizing of a model surface is performed twice using a contactless probe. The direction of the normal is accurately decided to enable a highly precise three-dimensional correction.
According to the present invention, there is provided a digitizing apparatus in which the surface of a model is traced by a probe which measures distance contactlessly, thereby forming digitizing data along the profiling path. The digitizing apparatus comprises direction setting means for setting a first profiling direction which defines the profiling path, and a second profiling direction which perpendicularly intersects the first profiling direction, memory means for storing tangent vectors computed from an error quantity between probe measurement distance and a reference distance in each of the profiling directions, arithmetic means for computing, from a vertical vector computed on the basis of the tangent vectors, a normal vector with regard to the surface of the model at a point of intersection between the two profiling directions, and correcting means for correcting, on the basis of the normal vector, digitizing data formed with regard to the first profiling direction.
The digitizing apparatus of the invention is such that the surface of a model M is digitized twice. That is, it is digitized along a first profiling path and along a second profiling path, using a contactless probe as shown in FIG. 4 so that the direction of the normal to the digitized model can be accurately corrected. Digitizing data can be formed which includes highly precise three-dimensional correction direction data.
BRIEF DESCRIPTION OF THE DRAWINGS
FIG. 1 is a block diagram of an embodiment according to the present invention;
FIG. 2 is a diagram for describing contactless profiling;
FIG. 3 is a block diagram of a digitizing apparatus which controls a probe;
FIG. 4 is a diagram of two profiling paths for digitizing a model surface; and
FIGS. 5 and 6 are graphs of a procedure for computing a normal vector at a point of intersection.
DESCRIPTION OF THE PREFERRED EMBODIMENT
An embodiment of the present invention will now be described in detail with reference to the drawings.
First, contactless profiling will be described with reference to FIG. 2. This is a method in which profiling data is formed, without making contact with the surface of a m
REFERENCES:
patent: 4424570 (1984-01-01), Imazeki et al.
patent: 4603285 (1986-07-01), Matsuura et al.
patent: 4654570 (1987-03-01), Yamazaki
patent: 4672190 (1987-06-01), Rostkowski et al.
Fanuc Ltd.
Ruggiero Joseph
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