Interactive graphics system and method for modelling physical articles

• US 4,979,224 A
• Filed: 09/27/1988
• Issued: 12/18/1990
• Est. Priority Date: 10/06/1987
• Status: Expired due to Fees

• Current Assignee: Digital Electronics Automation Incorporated
• Original Assignee: Digital Electronics Automation Incorporated
• Inventors: Basadonna, Luciano, Maiocco, Roberto
• Primary Examiner(s): Boudreau, Leo H.
• Assistant Examiner(s): Mancuso, Joseph
• Application Number:
  US07/249,803
• Time in Patent Office: 812 Days
• Field of Search: 382/8, 382/22, 382/1, 364/474.03, 364/474.02, 364/474.14, 364/474.37, 364/474.24, 364/474.29, 364/474.31, 364/474.33, 364/474.22
• US Class Current: 382/154
• CPC Class Codes: G05B 19/4207 in which a model is traced or scanned and corresponding data recorded
• CPC Class Codes: G05B 2219/34096 Approximate, replace curve, surface with circle, linear segments, least error
• CPC Class Codes: G05B 2219/34145 Bezier interpolation, spline
• CPC Class Codes: G05B 2219/34148 Coons interpolation, patch
• CPC Class Codes: G05B 2219/36438 Manually selection of points on surface to select area to scan automatically
• CPC Class Codes: G05B 2219/37207 Verify, probe, workpiece
• CPC Class Codes: Y02P 90/02 Total factory control, e.g. smart factories, flexible manufacturing systems [FMS] or integrated manufacturing systems [IMS]

Abstract

An interactive graphics system for modelling physical articles, includes a measurement device connected bi-directionally with a central unit to which a video screen and a keyboard are connected, as well as processing media which are suitable for receiving from the measurement device, at least, data on initial model identification points, and for controlling the automatic collection of addition data regarding the model by means of the same measurement equipment in order to provide such data for processing for use in deriving the model.

Claims

1. An interactive system for modelling a physical article in mathematical terms, comprising a measurement device for taking measurements of said article, and processing means coupled to said measurements device so as to receive data on initial identification points on the article for providing automatic signals to control said measurement device in the collection of data on additional points on the article, said processing means constructing a model from all of said data;

said processing means including equipment for the mathematical construction of boundary curves connecting said initial identification points for said model, equipment for the mathematical construction of a surface fitted to the boundary curves, and

means for determining data collection errors due to the dimensions of said probe of said measurement device and means for mathematically constructing, on the basis of a mathematically defined surface, a second surface free of said data collection errors.

2. A system in accordance with claim 1, wherein said measurement device comprises a probe for the collection of points on the physical article, and the positioning of said probe is automatically controlled by the automatic signals from said processing means.

3. A system in accordance with claim 1, wherein said measurement device comprises a probe for the collection of points on the physical article, and the automatic signals supplied by said processing means control the positioning of said probe for the collection of said additional points.

4. A system in accordance with claim 1, wherein the data on the initial identification points for the model are supplied by said measuring device.

5. A system in accordance with claim 1, wherein the data on the initial identification points for the model and supplied by digital data processing means.

6. A system in accordance with claim 1, wherein said processing means include equipment for the mathematical construction of a surface for said model, on the basis of the fitted surface and within the boundaries set by said additional points, which where collected for said physical article.

7. A system in accordance with claim 1, wherein said processing means include equipment for the detection of deviations between said mathematical construction of the surface of said article, and the corresponding surface of said physical article.

8. A system in accordance with claim 7, said deviations are between the corresponding points of said surfaces.

9. A system in accordance with claim 7, wherein said processing means include equipment for the statistical display of said deviations.

10. A system in accordance with claims 7, wherein said processing means include means for checking whether or not said deviations fit within a predetermined field.

11. A system in accordance with claim 1, wherein said processing means include equipment for the interactive approximation of curves and surfaces, based on calculations using Bezier formulas.

12. A system in accordance with claim 1, wherein said processing means are connected to display means and to communication means for an operator.

13. A system in accordance with claim 1, wherein said processing means include means for connection to an electronically controlled machine tool.

14. A method for modelling physical articles in a form usable by a program-controlled apparatus, said method being performed with measurement means capable of measuring points on the article, said method comprising the steps of:

a. defining an area to be measured on said article by specifying to said measurement means a set of control coordinates roughly defining the boundary of said area;

b. operating said measurement means to acquire measurements at additional points necessary to define the boundaries with a specified degree of accuracy;

c. modelling the boundary with a set of contouring defining equations so as to minimize the deviation thereof from the measured points;

d. operating said measurement means to acquire further measurements at selected points on the surface of said article;

e. comparing the acquired further measurements with values derived from the modelling contour-defining equations at the same points;

if the deviations are within predefined limits, stop, otherwise go to step f; and

f. modifying the contour-defining equations to minimize deviations of the model from measured points and returning to step d.

15. In a system for modelling physical articles in a form usable by a program-controlled machine, said system including measurement means capable of measuring points on the article, said system comprising:

a. means for defining an area to be measured on said article by specifying to said measurement means a set of control coordinates roughly defining the boundary of said area;

b. first means for operating said measurement means to acquire measurements at additional points necessary to define the boundaries with a specified degree of accuracy;

c. means for modelling the boundary with a set of contour-defining equations so as to minimize the deviation thereof from the measured points;

d. second means having an enabling input and being responsive to a signal received at said enabling input for operating said measurement means to acquire further measurements at selected points on the surface of said article;

e. means for comparing the acquired further measurements with the values derived from the modelling contour-defining equations at the same points;

said comparing means stopping further operation if the deviations are within predefined limits, and otherwise producing a continuation signal; and

f. means responsive to said continuation signal for modifying the contour-defining equations to minimize deviations of the model from measured points, said means for modifying producing a control signal applied to the enabling input of said second means for operating so as to enable the same to acquire further measurements.