Boots – shoes – and leggings
Patent
1991-01-08
1993-01-26
Smith, Jerry
Boots, shoes, and leggings
364191, G05B 19405, B23Q 35127
Patent
active
051827140
DESCRIPTION:
BRIEF SUMMARY
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to a digitizing control apparatus for successively receiving positional data and producing NC data while tracing the shape of a model, and more particularly to a digitizing control apparatus of simple arrangement which can obtain highly accurate data in a direction normal to the surface of a model.
2. Background of the Related Art
Heretofore, there has been employed a contact-type probe as a tracer head in a digitizing control apparatus. While the contact-type probe is being held in contact with a model surface, displacement information is obtained from the model surface by the probe, and feed control data or NC data are calculated from the obtained displacement information. However, the surface of a model which is of a soft material tends to be damaged by the pressure with which the probe is held against the model.
To overcome the above drawback, there has been developed a digitizing control apparatus which has a tracer head comprising a non-contact-type detector for detecting the distance up to the surface of a model in a non-contact manner.
Unlike the contact-type probe, however, the non-contact-type detector can detect only one-dimensional displacement information at one time. In order to obtain data in a direction normal to the surface of a model, which data are required to calculate a tool offset, for example, three non-contact-type detectors are employed to determine the coordinates of three points on the model surface, and a vector in the normal direction are calculated from the coordinates of the three points. According to another attempt, a zigzag tracing path is generated, and a vector in the normal direction is calculated from the coordinates of three points that are successively measured on the tracing path.
Use of the three non-contact-type detectors is not preferred because of the required high cost. Generation of the zigzag tracing path imposes mechanical limitations such as on a feed speed, etc., results in a reduced degree of accuracy, and takes an increased period of time for digitizing.
SUMMARY OF THE INVENTION
The present invention has been made in view of the aforesaid drawbacks. It is an object of the present invention to provide a digitizing control apparatus of simple arrangement which can obtain highly accurate data in a direction normal to the surface of a model.
To solve the above problems, there is provided in accordance with the present invention a digitizing control apparatus for successively receiving positional data and producing NC data while tracing the shape of a model, comprising a tracer head having first and second non-contact-type distance detectors for independently measuring distances up to the surface of the model, the first and second non-contact-type distance detectors being positioned to travel parallel to a feed direction, sampling means for sampling measured values from the first and second distance detectors at predetermined times, memory means for storing a previously sampled first measured value from the first non-contact-type distance detector and a previously sampled second measured value from the second non-contact-type distance detector, and calculating means for determining data in a normal direction of the surface of the model based on at least three of the first and second measured values, a presently sampled third measured value from the first non-contact-type distance detector, and a presently sampled fourth measured value from the second non-contact-type distance detector.
The coordinates of respective vertexes of a small rectangular shape on the surface of the model are determined on the basis of the previously and presently sampled measured values from the two distance detectors, and the vector in the normal direction is determined on the basis of the coordinates of three of the vertexes, so that the data in the normal direction are obtained.
BRIEF DESCRIPTION OF THE DRAWINGS
FIG. 1 is a block diagram showing the hardware arrangement of a digitizing contr
REFERENCES:
patent: 4396832 (1983-08-01), Henderson
patent: 4590580 (1986-05-01), Takezawa et al.
patent: 4679159 (1987-07-01), Yamazaki et al.
Fanuc Ltd.
Gordon Paul
Smith Jerry
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