US4595991A
Expired / Lapsed
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Position measuring method and apparatus
Assignee: Dr Johannes Heidenhain GmbH
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Filing: 1983-09-21
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Granted: 1986-06-17
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Expires: 2003-09-21
Abstract
Abstract A process and apparatus for obtaining harmonic-free periodic signals in an incremental measuring system is disclosed in which a graduation having a graduation period P is scanned by at least six scanning elements (for the case in which the previously determined bandwidth N of the analog signals obtained in scanning the graduation N is equal to 3). The periodic analog signals generated by the scanning elements are subjected to a Fourier analysis for the determination of the Fourier coefficients of the base or fundamental wave of the periodic analog signals. These Fourier coefficients are then evaluated as harmonic-free periodic signals for the formation of position measuring values.
Inventors
- 👤 Alfons Spies
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-30 06:50
CPC Classifications
G; G01; G01R; G01R23/00; G01R23/16; G01R23/165; G01R23/167; G01D; G01D5/00; G01D5/12; G01D5/244; G01D5/24409; H; H03; H03M; H03M1/00; H03M1/12; H03M1/22; H03M1/24; H03M1/28; H03M1/30
Claims Analysis
Total Claims: 15
Claim 1
Independent Claim
184 words
A method for generating harmonic-free periodic signals in an incremental or absolute measuring system comprising a scale which defines a graduation having a period P and a scanning unit which generates at least one scanning signal and scans the scale, said method comprising the following steps: determining a band width N characteristic of the at least one scanning signal; providing at least 2N scanning elements in the scanning unit to scan the period P of the graduation, each of which generates a respective scanning signal S n in response thereto; performing a Fourier analysis on the scanning signals to determine at least a pair of Fourier coefficients a 1 , b 1 ; U a , U b . . . characteristic of a lowest frequency Fourier component of the at least one scanning signal; and determining by means of an evaluation unit the position of the scanning unit with respect to the scale from an evaluation of the at least a pair of Fourier coeffients a 1 , b 1 ; U a , U b . . . as harmonic-free periodic signals.
Claim 2
Independent Claim
184 words
A method for generating harmonic-free periodic signals in an incremental or absolute measuring system comprising a scale which defines a graduation having a period P and a scanning unit which generates at least one scanning signal and scans the scale, said method comprising the following steps: determining a band width N characteristic of the at least one scanning signal; providing at least 2N scanning elements in the scanning unit to scan the period P of the graduation, each of which generates a respective scanning signal S n in response thereto; performing a Fourier analysis on the scanning signals to determine at least a pair of Fourier coefficients a 1 , b 1 ; U a , U b . . . characteristic of a lowest frequency Fourier component of the at least one scanning signal; and determining by means of an evaluation unit the position of the scanning unit with respect to the scale from an evaluation of the at least a pair of Fourier coeffients a 1 , b 1 ; U a , U b . . . as harmonic-free periodic signals.
Claim 3
Dependent Claim
99 words
The method of claim 1 wherein the performing step comprises the step of digitizing the scanning signals and computationally determining the at least a pair of Fourier coefficients a 1 , b 1 ; U a , U b . . . from the digitized scanning signals; and wherein the evaluating step comprises the step of determining a phase position φ within a period P of the graduation as an arctangent function of a ratio of the at least a pair of Fourier coefficients a 1 , b 1 ; U a , U b . . . .
Claim 4
Dependent Claim
117 words
The invention of claim 1 wherein the performing step comprises the following steps: multiplying each of the scanning signals S n by a factor cos(π(n-1)/N) to generate a plurality of first multiplied scanning signals; summing the first multiplied scanning signals to generate a first analog signal U a ; multiplying the scanning signals S n by a factor sin(π(n-1)/N) to generate a plurality of second multiplied scanning signals; summing the second multiplied scanning signals to generate a second analog signal U b ; and wherein the evaluating step comprises the step of determining a phase position φ within a graduation period P of the graduation from the harmonic-free free periodic analog signals U a ,U b .
Claim 5
Dependent Claim
149 words
In a position measuring system comprising a measuring scale which comprises a periodic graduation and a scanning unit adapted to scan the measuring scale, the improvement comprising: at least 2N scanning elements, each included in the scanning unit to scan the periodic graduation and to generate a respective periodic scanning signal in response thereto, each of said scanning signals including a fundamental component and (N-1) harmonic components; means for performing a Fourier analysis on the scanning signals to determine at least a pair of Fourier coefficients a 1 , b 1 ; U a , U b . . . characteristic of the fundamental component of the scanning signals; and means for evaluating the at least a pair of Fourier coefficients a 1 , b 1 ; U a , U b . . . to determine the position of the scanning unit with respect to the measuring scale.
Claim 6
Dependent Claim
149 words
In a position measuring system comprising a measuring scale which comprises a periodic graduation and a scanning unit adapted to scan the measuring scale, the improvement comprising: at least 2N scanning elements, each included in the scanning unit to scan the periodic graduation and to generate a respective periodic scanning signal in response thereto, each of said scanning signals including a fundamental component and (N-1) harmonic components; means for performing a Fourier analysis on the scanning signals to determine at least a pair of Fourier coefficients a 1 , b 1 ; U a , U b . . . characteristic of the fundamental component of the scanning signals; and means for evaluating the at least a pair of Fourier coefficients a 1 , b 1 ; U a , U b . . . to determine the position of the scanning unit with respect to the measuring scale.
Claim 7
Dependent Claim
94 words
The invention of claim 4 wherein the performing means comprises: means for digitizing the scanning signals; and a computer, responsive to the digitized scanning signals, for computationally determining the at least a pair of Fourier a 1 , b 1 ; U a , U b . . . coefficients; and wherein the evaluating means comprises means for determining a phase position φ as an arctangent function of a ratio of the at least a pair of Fourier coefficients a 1 , b 1 ; U a , U b . . . .
Claim 8
Dependent Claim
134 words
The invention of claim 4 wherein the scanning signals are designated S 1 . . . S n . . . S 2N , and wherein the performing means comprises: means for multiplying each of scanning signals S n by a factor cos(π(n-1)/N) to generate respective first multiplied scanning signals; means for summing the first multiplied scanning signals to generate a first analog signal U a ; means for multiplying each of the scanning signals S n by a factor sin(π(n-1)/N) to generate respective second multiplied scanning signals; means for summing the second multiplied scanning signals to generate a second analog signal U b ; and wherein the evaluating means comprises means for determining a phase position within a period of the graduation φ according to the relationship φ=arctan (U a /U b ).
Claim 9
Dependent Claim
17 words
The invention of claim 4 further comprising: means for displaying the position determined by the evaluating means.
Claim 10
Dependent Claim
59 words
The invention of claim 4 wherein the graduation defines a period P; wherein each of the scanning elements defines a width B along a measuring direction; wherein the width B is less than P/2N; and wherein the scanning elements are arranged in the scanning unit at a spacing of P/2N+zP, wherein z=0, 1, 2, . . . , respectively.
Claim 11
Dependent Claim
76 words
The invention of claim 4 wherein the graduation defines a period P; wherein each of the scanning elements defines a width B along a measuring direction; wherein the width B is greater than the period P; wherein each of the scanning elements defines alternating signal active zones and signal inactive zones; and wherein the scanning elements are arranged in the scanning unit at a spacing of B+zP+P/2N, where z=0, 1, 2, . . . , respectively.
Claim 12
Dependent Claim
33 words
The invention of claim 4 wherein the evaluating means comprises: means for digitizing each of the scanning signals; a computer; and means for applying the digitized scanning signals as inputs to the computer.
Claim 13
Dependent Claim
54 words
The invention of claim 4 wherein the evaluating means comprises: a plurality of amplifiers, responsive to the scanning signals, for generating a plurality of amplified scanning signals; a plurality of differential amplifiers; and means for applying the amplified scanning signals via a plurality of resistors as input signals to the plurality of differential amplifiers.
Claim 14
Dependent Claim
46 words
The invention of claim 4 wherein the evaluating means comprises: a direction discriminator responsive to the at least a pair of Fourier coefficients a 1 , b 1 ; U a , U b . . . ; and an up-down counter coupled to the discriminator.
Claim 15
Dependent Claim
22 words
The invention of claim 4 wherein the evaluating means comprises: means for generating interpolation values within a signal period of the graduation.
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USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1989-06-16 | 1989-12-16 | 1990-06-17 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1993-06-16 | 1993-12-16 | 1994-06-17 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1997-06-16 | 1997-12-16 | 1998-06-17 | $7700.00 | Window Closed / Lapsed |