Rotary encoder
First Claim
Patent Images
1. A rotary encoder comprising:
- a fixed section;
a rotating section which can be rotated with reference to the fixed section;
angle detecting means for detecting a rotation angle of the rotating section with reference to a predetermined reference position of the rotating section; and
output means for outputting the detected angle, wherein, when the angle detecting means detects an angle θ
n=n×
θ
s (n=1, 2, . . . , N (where N×
θ
s=360°
)) which is an integer multiple of a predetermined angle θ
s (θ
s≧
output resolution) such that the rotating section is rotated, an angle error E (θ
n) included in the detected angle θ
n is measured, functions between the detected angles θ
n and errors E(θ
n) are defined by the following equation with respect to all n;
an amplitude Ai and an initial phase φ
i (i=1, 2, . . . , N/2 or (N−
1)/2) are calculated such that all the defined equations are satisfied, storing means for storing an error function which is given by the following equation;
and which is a periodic function of a detected angle θ
a having the calculated amplitude Ai and the calculated initial phase φ
i as coefficients is arranged, the detected angle θ
a detected by the angle detection means is substituted for the variables θ
in the equation of the error function E(θ
) stored by the storing means, and a value obtained by subtracting the value E(θ
a) obtained by the substitution from the detected angle θ
a is outputted by the output means.
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Abstract
There is provided a rotary encoder which can eliminate an angle error caused by an eccentricity from a measured angle without strictly adjusting hardware and which can also eliminate a graduation error. Detection of a rotation angle of the rotating section and measurement of an error E (θn) included in the detected angle θ are performed in advance, an error function E(θ) represented by a periodic function of the detected angle θ is calculated on the basis of these values, a storing means for storing the periodic function of the calculated error E(θ) is arranged, and an angle obtained by subtracting a value obtained by substituting the detected angle θa for variables in the error function E(θ) from the detected angle θa is displayed on a display unit.
15 Citations
2 Claims
-
1. A rotary encoder comprising:
- a fixed section;
a rotating section which can be rotated with reference to the fixed section;
angle detecting means for detecting a rotation angle of the rotating section with reference to a predetermined reference position of the rotating section; and
output means for outputting the detected angle, wherein, when the angle detecting means detects an angle θ
n=n×
θ
s (n=1, 2, . . . , N (where N×
θ
s=360°
)) which is an integer multiple of a predetermined angle θ
s (θ
s≧
output resolution) such that the rotating section is rotated, an angle error E (θ
n) included in the detected angle θ
n is measured, functions between the detected angles θ
n and errors E(θ
n) are defined by the following equation with respect to all n;
an amplitude Ai and an initial phase φ
i (i=1, 2, . . . , N/2 or (N−
1)/2) are calculated such that all the defined equations are satisfied, storing means for storing an error function which is given by the following equation;
and which is a periodic function of a detected angle θ
a having the calculated amplitude Ai and the calculated initial phase φ
i as coefficients is arranged, the detected angle θ
a detected by the angle detection means is substituted for the variables θ
in the equation of the error function E(θ
) stored by the storing means, and a value obtained by subtracting the value E(θ
a) obtained by the substitution from the detected angle θ
a is outputted by the output means.
- a fixed section;
-
2. A rotary encoder comprising:
- a fixed section;
a rotating section which can be rotated with reference to the fixed section;
angle detecting means for detecting a rotation angle of the rotating section with reference to a predetermined reference position of the rotating section; and
output means for outputting the detected angle, wherein, when the angle detecting means detects an angle θ
n=n×
θ
s (n=1, 2, . . . , N (where N×
θ
s=360°
)) which is an integer multiple of a predetermined angle θ
s (θ
s≧
output resolution) such that the rotating section is rotated, an angle error E (θ
n) included in the detected angle θ
n is measured, combinations between the detected angles θ
n and errors E(θ
n) are defined by the following equation with respect to all n;
an amplitude Ai and an initial phase φ
i (i=1, 2, . . . , N/2 or (N−
1)/2) are calculated such that all the defined equations are satisfied, storing means for storing an error function which is given by the following equation;
and which is a periodic function of the detected angle θ
a having at least one amplitude Ak1, Ak2, . . . , Akm and at least one initial phase φ
k1, φ
k2, . . . , φ
km (k1, k2, . . . , km is at least one of natural numbers from 1 to N/2 or (N−
1)/2) of the calculated amplitudes Ai and the calculated initial phases φ
i as coefficients is arranged, the detected angle θ
a detected by the angle detection means is substituted for the variables θ
in the equation of the error function E(θ
) stored by the storing means, and a value obtained by subtracting the value E(θ
a) obtained by the substitution from the detected angle θ
a is outputted by the output means.
- a fixed section;
Specification
-
- Resources
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Current AssigneeSokkia Co. Ltd. (Topcon Corporation)
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Original AssigneeSokkia Co. Ltd. (Topcon Corporation)
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InventorsNakamura, Yutaka, Yanobe, Satoshi
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Primary Examiner(s)Fulton, Christopher W.
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Assistant Examiner(s)COURSON, TANIA C
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Application NumberUS10/726,639Publication NumberTime in Patent Office607 DaysField of Search33/1.PT, 33/1.N, 335/34, 337/06, 337/07US Class Current33/1.0PTCPC Class CodesG01D 18/001 Calibrating encodersG01D 5/2449 using hard-stored calibrati...
