Method for determining position within the measuring volume of a coordinate ...

United States Patent m

Bell et al.

[ii] Patent Number: 4,945,501 [45] Date of Patent: Jul. 31,1990

[54] METHOD FOR DETERMINING POSITION WITHIN THE MEASURING VOLUME OF A COORDINATE MEASURING MACHINE AND THE LIKE AND SYSTEM THEREFOR

[75] Inventors: Frederick K. Bell, Centerville;

Stephen N. Brown; Michael T. Gale,

both of Dayton, all of Ohio

[73] Assignee: The Warner & Swasey Company, Cleveland, Ohio

[21] Appl. No.: 338,378

[22] Filed: Apr. 12,1989

Related U.S. Application Data

[63] Continuation of Ser. No. 4,435, Jan. 20, 1987, abandoned.

[51] Int. CI.* G01C 25/00; G06F 15/46;

G05D 23/275

[52] U.S. CI 364/571.05; 318/632;

364/560; 364/474.35; 364/167.01; 33/503;

33/505; 33/556

[58] Field of Search 364/571.05, 571.04,

364/167.01, 164, 474.35, 550, 551.02, 559-563; 33/503, 505, 545, 546, 553-558; 318/632

[56] References Cited

U.S. PATENT DOCUMENTS

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4,550,418 10/1985 Deis 364/561 X

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4,582,026 4/1986 Takita et al 364/164 X

4,583,159 4/1986 Kanemoto et al 364/571 X

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FOREIGN PATENT DOCUMENTS

2739527 10/1978 Fed. Rep. of Germany .

1173313 2/1959 France .

1350652 12/1963 France .

216942A 2/1986 United Kingdom .

OTHER PUBLICATIONS

"Error Compensation of Coordinate Measuring Machines" dated Jan. 1985, and published in the Annals of CIRP by G. Zhang et al.

Primary Examiner—Parshotam S. Lall

Assistant Examiner—Joseph L. Dixon

Attorney, Agent, or Firm—David R. Syrowik; Raymond

J. Eifler

[57] ABSTRACT

Axis correction or machine charateristic data is stored (108) in memory (110) within a control or measurement processor (36) of a CMM (10) (FIG. 8). The axis correction data includes error data representing 21 different geometry errors (FIG. 4A through 4C) of the CMM. As position information is required, the measurement processor captures the actual position signal from each machine axis sensor and uses this position signal to locate (112) a set of the axis correction data which de* scribes the machine characteristics at that position. The measurement processor then mathematically combines (114) (FIG. 9) the position signal with the subset of axis correction data to obtain a corrected position signal having a corrected set of cooridinate values which describe the probe position in a true Cartesian coordinate system.

8 Claims, 8 Drawing Sheets