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US4771237A
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Method and apparatus for calibrating a displacement probe using a polynomial equation to generate a displacement look-up table
Assignee: Panametrics LLC
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Filing: 1986-02-19
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Granted: 1988-09-13
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Expires: 2006-02-19
Abstract
Abstract A method and apparatus for calibrating a displacement probe, such as a Hall effect displacement probe, wherein a preassembled probe is clamped in a calibration fixture which includes a calibration target and facility for selectively varying displacement between the target and the probe measurement tip. Probe output is read and stored at each of a plurality of preselected target/probe displacements. The stored output v. displacement data set is then employed to generate a polynomial equation which approximates probe output as a function of displacement. A displacement v. output look-up table unique to that probe is then generated from the polynomial approximation for a multiplicity of discrete displacement increments.
Inventors
- 👤 Clifton G. Daley
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-24 04:43
CPC Classifications
G; G01; G01D; G01D18/00; G01D18/008
Claims Analysis
Total Claims: 3
Claim 1
Independent Claim
195 words
A method of individually calibrating a displacement probe, such as a Hall effect displacement probe, having a monotonic output characteristic over a predetermined displacement range comprising the steps of: (a) fixturing a probe in a calibration fixture which includes a calibration target and means for selectively varying displacement d between said target and said probe, (b) reading output p 1 , p 2 . . . p m of said probe at each of a plurality of preselected target/probe displacements d 1 , d 2 , . . . d m within said range, (c) generating constants a 0 , a 1 , . . . a n according to the equation: A=P·C where A=[a.sub.0 a.sub.1 a.sub.2 - - - a.sub.n ] P=[p.sub.1 p.sub.2 p.sub.3 - - - p.sub.m ] C=[D'·(D·D').sup.-1 ] ##EQU2## D' is the transpose of matrix D, the superscript -1 denotes matrix inversion, and n and m are integers with m being greater than or equal to n+1 and (d) generating a look-up table unique to said probe relating probe output P to displacement d over said range according to the equation: p=a.sub.0 +a.sub.1 d+a.sub.2 d.sup.2 + - - - +a.sub.n d.sup.n.
Claim 2
Independent Claim
195 words
A method of individually calibrating a displacement probe, such as a Hall effect displacement probe, having a monotonic output characteristic over a predetermined displacement range comprising the steps of: (a) fixturing a probe in a calibration fixture which includes a calibration target and means for selectively varying displacement d between said target and said probe, (b) reading output p 1 , p 2 . . . p m of said probe at each of a plurality of preselected target/probe displacements d 1 , d 2 , . . . d m within said range, (c) generating constants a 0 , a 1 , . . . a n according to the equation: A=P·C where A=[a.sub.0 a.sub.1 a.sub.2 - - - a.sub.n ] P=[p.sub.1 p.sub.2 p.sub.3 - - - p.sub.m ] C=[D'·(D·D').sup.-1 ] ##EQU2## D' is the transpose of matrix D, the superscript -1 denotes matrix inversion, and n and m are integers with m being greater than or equal to n+1 and (d) generating a look-up table unique to said probe relating probe output P to displacement d over said range according to the equation: p=a.sub.0 +a.sub.1 d+a.sub.2 d.sup.2 + - - - +a.sub.n d.sup.n.
Claim 3
Dependent Claim
40 words
The method set forth in claim 1 comprising the additional steps of: (e) dividing said predetermined displacement range into a plurality of regions, and (f) performing said steps (b) through (d) sequentially for displacements d within each of said regions.
References Cited (Backward Citations)
USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1991-09-13 | 1992-03-14 | 1992-09-13 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1995-09-13 | 1996-03-14 | 1996-09-13 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1999-09-13 | 2000-03-14 | 2000-09-13 | $7700.00 | Window Closed / Lapsed |