Information processing apparatus, and recording medium storing computer program

Patent metadata

Field	Value
Publication number	US-2017317618-A1
Application number	US-201715495833-A
Country	US
Kind code	A1
Filing date	Apr 24, 2017
Priority date	May 2, 2016
Publication date	Nov 2, 2017
Grant date	—

Abstract

An information processing apparatus includes an acquisition unit configured to acquire a first phase signal and a second phase signal that are acquired by measuring a rotation of a moving object, and a calculation unit configured to calculate a rotational angle by an iterative calculation so as to satisfy a relational expression bearing an arctangent. The relational expression bearing the arctangent uses a first cosine wave and a second cosine wave at a higher harmonic of the first cosine wave for the first phase signal, and a first sine wave and a second sine wave at a higher harmonic of the first sine wave for the second phase signal. The first phase signal and the second phase signal may, for example, be analog signals having a wave shape.

First claim

What is claimed is:

1 . An information processing apparatus comprising:
an acquisition unit configured to acquire a first phase signal and a second phase signal that are acquired by measuring a rotation of a moving object; and a calculation unit configured to calculate a rotational angle by an iterative calculation so as to satisfy a relational expression bearing an arctangent, the relational expression bearing the arctangent using a first cosine wave and a second cosine wave at a higher harmonic of the first cosine wave for the first phase signal, and a first sine wave and a second sine wave at a higher harmonic of the first sine wave for the second phase signal.

2 . The information processing apparatus according to claim 1 , wherein at least one of the first phase signal and the second phase signal is at least one of an analog signal and a signal having a wave shape.

3 . The information processing apparatus according to claim 1 , further comprising a control unit configured to control a device based on the calculated rotation angle.

4 . The information processing apparatus according to claim 1 , wherein the iterative calculation is a CORDIC calculation.

5 . The information processing apparatus according to claim 1 , wherein initial values of the first sine wave and the second sine wave are zero in the iterative calculation.

6 . The information processing apparatus according to claim 4 , wherein the calculation unit includes a correction unit configured to correct an absolute value of coordinate data in the CORDIC calculation.

7 . The information processing apparatus according to claim 1 , wherein the calculation unit includes a plurality of calculation circuits configured to carry out respective calculations included in the iterative calculation, and
wherein the calculation circuits are connected together as a pipeline.

8 . The information processing apparatus according to claim 1 , wherein the calculation unit includes a plurality of calculation circuits configured to carry out respective calculations included in the iterative calculation, and
wherein the calculation circuits are connected together recursively.

9 . The information processing apparatus according to claim 1 , further comprising an output unit configured to output a signal in which at least any one component of the second cosine wave and the second sine wave is removed.

10 . The information processing apparatus according to claim 9 , wherein the output unit outputs the signal as an encoder signal indicating a positional displacement of the moving object.

11 . The information processing apparatus according to claim 1 , further comprising a control unit configured to control a rotation of a motor that controls a position of the moving object based on a result of the calculation by the calculation unit.

12 . A recording medium storing a program that upon execution by a computer causes the computer to function as an information processing apparatus comprising:
an acquisition unit configured to acquire a first phase signal and a second phase signal that are acquired by measuring a rotation of a moving object; and a calculation unit configured to calculate a rotational angle by an iterative calculation so as to satisfy a relational expression bearing an arctangent, the relational expression bearing the arctangent using a first cosine wave and a second cosine wave at a higher harmonic of the first cosine wave for the first phase signal, and a first sine wave and a second sine wave at a higher harmonic of the first sine wave for the second phase signal.

13 . An information processing apparatus configured to process two-dimensional coordinate data including a fundamental frequency and a harmonic to calculate an argument of a vector of the fundamental frequency in the two-dimensional coordinate data, the information processing apparatus comprising:
a fundamental frequency selector configured to select coordinate data of the fundamental frequency in the two-dimensional coordinate data at a first calculation, and select fundamental frequency rotated coordinate data at a second and subsequent calculations; a harmonic selector configured to select coordinate data of the harmonic in the two-dimensional coordinate data at the first calculation, and select harmonic rotated coordinate data at the second and subsequent calculations; a rotational direction determination unit configured to determine a rotational direction based on the coordinate data selected by the fundamental frequency selector and the coordinate data selected by the harmonic selector; a fundamental frequency rotational calculation unit configured to rotate the coordinate data selected by the fundamental frequency selector in the rotational direction determined by the rotational direction determination unit, and output the rotated coordinate data to the fundamental frequency selector as the fundamental frequency rotated coordinate data; a harmonic rotational calculation unit configured to rotate the coordinate data selected by the harmonic selector in the rotational direction determined by the rotational direction determination unit, and output the rotated coordinate data to the harmonic selector as the harmonic rotated coordinate data; and a rotational angle cumulative addition unit configured to cumulatively add a rotational angle by which the coordinate data is rotated by the fundamental frequency rotational calculation unit based on the rotational direction determined by the rotational direction determination unit to converge the rotational angle to the argument of the vector of the fundamental frequency in the two-dimensional coordinate data.

14 . The information processing apparatus according to claim 13 ,
wherein the fundamental frequency rotational calculation unit rotates the coordinate data by a rotational angle of tan −1 (2 −i ) in an i-th cycle (i is zero or a larger integer), and wherein the harmonic rotational calculation unit rotates the coordinate data by a rotational angle acquired by multiplying the rotational angle of the fundamental frequency rotational calculation unit by an order of the harmonic.

15 . The information processing apparatus according to claim 13 ,
wherein the harmonic selector includes a third harmonic selector configured to select coordinate data of a third harmonic in the two-dimensional coordinate data at the first calculation and select third harmonic rotated coordinate data at the second and subsequent calculations, wherein the rotational direction determination unit determines the rotational direction based on the coordinate data selected by the fundamental frequency selector and the coordinate data selected by the third harmonic selector, and wherein the harmonic rotational calculation unit includes a third harmonic rotational calculation unit configured to rotate the coordinate data selected by the third harmonic selector in the rotational direction determined by the rotational direction determination unit to output the rotated coordinate data to the third harmonic selector as the third harmonic rotated coordinate data.

16 . The information processing apparatus according to claim 15 ,
wherein the fundamental frequency rotational calculation unit rotates the coordinate data by a rotational angle of tan −1 (2 −i ) in an i-th cycle (i is zero or a larger integer), and wherein the third harmonic rotational calculation unit rotates the coordinate data by a rotational angle of 3×tan −1 (2 −i ) in the i-th cycle.

17 . The information processing apparatus according to claim 13 ,

Assignees

• Canon Kk

Inventors

• Mizoguchi Masahiko
• Nakayama Tadayoshi
• Aida Toru

Classifications

• G01D5/3473 Primary

  Circular or rotary encoders · CPC title

• H02K11/22

  Optical devices · CPC title

• H02K11/30

  Structural association with control circuits or drive circuits · CPC title

• H02P6/08 Primary

  Arrangements for controlling the speed or torque of a single motor (H02P6/10, H02P6/28 take precedence) · CPC title

• G01D5/34707

  Scales; Discs, e.g. fixation, fabrication, compensation · CPC title