JPH09269240A - Turning angle measuring device and method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To realize high accuracy measurement over a wide measuring range by detecting a turning angle with both rough and minute accuracy, converting them into digital signals, and replacing the lower bits of the rough digital signal with the minute digital signal. SOLUTION: Gradation 1a is spaced so that the output of an analog-to-digital converter 3 becomes binary value 2<16> when a rotary encoder 1 is rotated by 360 deg., and gradation 2a is minutely spaced so that the output becomes binary value 2<16> when a rotary encoder 2 is rotated by 5 deg.. A CPU 5 adds 16 bits of a second digital signal D in place of the lower 9 bits, largely influenced by noise, out of a first digital signal C formed of 16 bits so as to generate a binary coded digital signal of 23 bits in total as a third measuring digital signal E. This combined signal E of 23 buts becomes OOOOOOH-7FFFFFH at the time of hexadecimal notation. The CPU 5 converts the measuring digital signal E into the numerical value shown on an angle unit of degree, radian, or the like, and outputs it to an output device 6.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a rotation angle measuring device and method, and more particularly to a technique for detecting a rotation angle with high accuracy over a wide detection range.

[0002]

2. Description of the Related Art A rotation detecting means such as a rotary encoder is mounted on a rotating body,
There is a rotation angle measuring device that outputs a rotation angle of a rotating body as a numerical value by converting an output signal (analog signal) of the rotation detecting means into a digital signal using an analog-digital converter.

By the way, in such a conventional rotation angle measuring device, when it is attempted to measure the rotation angle over one round (that is, 360 °) of the rotating body by using an analog-digital converter having a specific number of bits, 360 It is said that the measurement accuracy becomes rough compared to the case where the rotation angle is measured over 90 °, which is narrower than 90 °, and the measurement range becomes narrower when the measurement accuracy is improved. There was a problem.

The present invention has been made in view of the above problems, and an object of the present invention is to provide a rotation angle measuring device and method capable of realizing highly accurate rotation angle measurement in a wide measurement range.

[0005]

In order to achieve the above object, as a first means, a rotation detecting means for detecting a rotation angle of a rotating body with coarse precision and fine precision respectively and outputting it as an analog signal, Apparatus comprising analog-digital conversion means for converting each analog signal into a digital signal respectively, and arithmetic means for generating a measurement digital signal in which lower bits of a digital signal based on coarse precision are replaced with digital signals based on fine precision Is adopted.

As a second means, a device is adopted in which, in the first means, the arithmetic means converts the measured digital signal into a signal in units of angles.

As a third means, a step of detecting the rotation angle of the rotating body as an analog signal with coarse accuracy and a fine accuracy, a step of converting each analog signal into a digital signal, and a digital signal based on the coarse accuracy. Generating a measurement digital signal in which the lower bits of the are replaced with a digital signal based on a fine precision.

As a fourth means, there is adopted a method including the step of converting the measured digital signal into a signal in units of angles in the third means.

[0009]

BEST MODE FOR CARRYING OUT THE INVENTION An embodiment of a rotation angle measuring apparatus and method according to the present invention will be described below with reference to FIGS. 1 and 2.

FIG. 1 is a block diagram showing the configuration of this embodiment. In this figure, reference numerals 1 and 2 are rotary encoders (rotation detecting means), 3 and 4 are A / D converters (analog / digital converting means), 5 is a CPU (calculating means), and 6 is an output device.

The rotary encoders 1 and 2 are coaxially attached to a rotating body (not shown) via a rotating shaft, and rotate simultaneously with the rotation of the rotating body. Scales 1a are formed on the outer periphery of the rotary encoder 1 at equal intervals, and the rotary encoder 1 uses an analog signal of a level proportional to the number of the scales 1a detected (scale number) as the first angle detection signal A / A. Output to the D converter 3.

On the other hand, scales 2a are formed on the outer circumference of the rotary encoder 2 at equal intervals, and the rotary encoder 2 outputs an analog signal of a level proportional to the number of the scales 2a detected (scale number) as the second angle detection signal B. Is output to the A / D converter 4.

The A / D converter 3 converts the first angle detection signal A into a binary digital signal (first digital signal) C having a bit length of 16 bits, and the A / D converter 4 detects the second angle detection. The signal B is converted into a binarized digital signal (second digital signal) D having a bit length of 16 bits and output to the CPU 5. That is, the A / D converters 3 and 4 convert the level of the signal input to each to a binary number in the range of 0 to 2 ¹⁶ (measurement range) and output it to the CPU 5.

Here, the interval between the scales 1a is equal to the scale 2a.
Is formed coarser than the interval. That is, as shown in FIG. 2, the graduation 1a has, for example, an output of the A / D converter 3 of 2 when the rotary encoder 1 rotates 360 °.
It is provided at intervals such that the decimal value becomes 2 ¹⁶ . On the other hand, the scales 2a are provided at minute intervals so that the output of the A / D converter 4 becomes a binary value 2 ¹⁶ when the rotary encoder 2 rotates 5 °.

The CPU 5 synthesizes the first digital signal C and the second digital signal D in the following procedure to generate a measurement digital signal E indicating the rotation angle of the rotating body.
That is, as shown in FIG. 3, the first 16 bits
Of the digital signals C of
The second digital signal D is added in place of the bits to make a total of 23
A binary digitized digital signal is generated as a measurement digital signal E.

The 23-bit measured digital signal E synthesized in this way is 000000H to 7FF in hexadecimal notation.
It will be FFFH. The CPU 5 converts the measured digital signal E into a numerical value such as “°” or “radian” with the angle as a unit and outputs the numerical value to the output device 6. The output device 6 is, for example, a monitor or a printer, and numerically displays or prints the angle of the rotating body.

[0017]

As described above, according to the rotation angle measuring apparatus and method of the present invention, the following effects can be obtained. That is, the rotation detection means for detecting the rotation angle of the rotating body with coarse precision and fine precision respectively and outputting it as an analog signal, the analog / digital conversion means for converting each analog signal into a digital signal respectively, and the coarse precision are used. Since the measurement digital signal is generated by replacing the lower bit of the digital signal with the digital signal based on the fine precision, for the lower bit, that is, the bit indicating the fine rotation angle, the digital signal based on the fine precision and the bit other than the lower bit. For bits, a measurement digital signal is generated from a digital signal with a coarse accuracy and a wide measurement range. Therefore, highly accurate rotation angle measurement can be realized over a wide measurement range.

[Brief description of drawings]

FIG. 1 is a block diagram showing an embodiment of a rotation angle measuring apparatus and method according to the present invention.

FIG. 2 is an explanatory diagram showing a relationship between a first digital signal and a second digital signal in the rotation angle measuring device and method according to the present invention.

FIG. 3 is an explanatory diagram showing a method of generating a measurement digital signal in the rotation angle measuring device and method according to the present invention.

[Explanation of symbols]

1, 2 rotary encoder (rotation detecting means) 1a, 2a scale 3, 4 A / D converter (analog / digital converting means) 5 CPU (calculating means) 6 output device

Claims (4)

[Claims] 1. A rotation detecting means for detecting a rotation angle of a rotating body with coarse precision and fine precision and outputting as an analog signal, and an analog / digital converting means for converting each analog signal into a digital signal, respectively. A rotation angle measuring device comprising: an arithmetic unit that generates a measurement digital signal by replacing a lower-order bit of a precision-based digital signal with a precision-based digital signal. 2. The rotation angle measuring device according to claim 1, wherein the calculation means converts the measured digital signal into a signal in which an angle is a unit. 3. A method according to claim 1, wherein: a. Detecting the rotation angle of the rotating body as an analog signal with coarse and fine accuracy, b. Converting each of the analog signals into a digital signal, and c. A rotation angle measuring method comprising: a step of generating a measurement digital signal in which a lower bit of a digital signal based on coarse accuracy is replaced with a digital signal based on fine accuracy. 4. The method according to claim 3, further comprising the step of converting the measurement digital signal into a signal in units of angles.
The rotation angle measurement method described.