KR20030087257A - Digital optical angle sensor - Google Patents

Abstract

PURPOSE: A digital optical angle sensor is provided to precisely measure an absolute angle displacement of a rotator by detecting a coarse angle and a fine angle through measuring data including a pseudo-random code and a triangle code. CONSTITUTION: A digital optical sensor is mounted on a rotator(2) rotated about a rotating shaft(1). The digital optical sensor includes a grating element section(3) and a detecting section. The grating element section(3) includes a pseudo-random code for detecting a coarse angle and a triangle code for detecting a fine angle. The detecting section includes a detector, an A/D converter for converting a displacement signal into a digital signal, and a processor for measuring an angular position by detecting the coarse angle and the fine angle from the digital signal converted by the A/D converter.

Description

Digital optical angle sensor {DIGITAL OPTICAL ANGLE SENSOR}

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a digital optical angle sensor, and in particular, an arbitrary code having a difference in transmittance or reflectance in a sensing unit consisting of a photo emitting device and a photo detecting device. The present invention relates to a digital optical angle sensor capable of precisely measuring the absolute rotation angle of a rotating body by measuring an angular position by measuring data expressed in degrees).

The angle sensor is a sensor for measuring relative and absolute displacement caused by external influences, and the accuracy of a general angle sensor required by a power steering system of a conventional vehicle was about 0.1 degree.

However, in the Electric Power Steering (EPS) system, in which all parts of the power steering system are converted into an electric power system, it is necessary to measure an accurate and high absolute angle displacement of the steering shaft.

Most of the angle sensors currently in use adopt a method of measuring an angle using a change in magnetic quantity, that is, a method using a magnetic displacement measuring device, and the development of an angle sensor using optics is being carried out by only a few companies.

The present invention has been made in view of the above, and an object thereof is an arbitrary code having a difference in transmittance or reflectance in a sensing unit composed of a light emitting element and a light receiving element, that is, a fuse-random code. Rotors by detecting the Coarse Angle and the Fine Angle by measuring the data expressed by and the Triangle Code, and then detecting the angular position according to the combined combination of the detected Angle and Fine Angle. It is to provide a digital optical angle sensor that can accurately measure the absolute angle of rotation.

1 is an overall structural diagram of a digital optical angle sensor according to the present invention;

2 is a block diagram of a sensing unit in a digital optical angle sensor according to the present invention;

3 is a view showing the form of the code detected by the detection unit in the digital optical angle sensor according to the present invention.

<Description of the symbols for the main parts of the drawings>

1: rotating shaft 2: rotating body

3: grating element part 4: sensing part

5: detector 6: A / D converter

7: processor

The digital optical angle sensor of the present invention for achieving the above object, the metal to detect the fuse dough-random code and the fine angle engraved on the surface of the metal rotating body to be rotated about the axis of rotation to detect the curvature angle A grating element portion composed of a triangle cord engraved on the surface of the rotating body, a detector for detecting a displacement signal of the grating element portion using a line image sensor or a CCD image sensor as a light emitting element and a light receiving element, and a displacement signal detected by the detector A / D converter for converting a digital signal into a digital signal, and a detector configured to detect a curse angle and a fine angle from the digital signal converted by the A / D converter and combine the same to finally measure the angular position. .

Hereinafter, with reference to the accompanying drawings will be described in detail the configuration and operation of the digital optical angle sensor according to the present invention.

1 is an overall structural diagram of a digital optical angle sensor according to the present invention, in which the digital optical angle sensor mounted on the rotating body 2 of the disks 1 and 2 rotated about the rotation axis 1 has a large grating element. It consists of a part (3) and a detector (4).

As shown in Fig. 1, the grating element portion 3 is engraved on the surface of the disks 1 and 2 to detect the fine angle and the fuse-door random code engraved on the surfaces of the disks 1 and 2 to detect the curse angle. Consists of triangle cords.

As illustrated in FIG. 2, the sensing unit 4 senses a displacement signal of the grating element unit 3 using a line image sensor or a CCD image sensor as a light emitting element and a light receiving element. A detector (5), an A / D converter (6) for converting the displacement signal detected by the detector (5) into a digital signal, and the digital converted by the A / D converter (6). It consists of a processor 7 which detects the curse angle and the fine angle from the signal and combines them to finally measure the angular position.

Meanwhile, as shown in FIG. 1, the line image sensor as the detector 5 in the sensing unit 4, and the fuse-random code and the triangle code of the grating element unit 3 are the axes of rotation of the rotating body 2. It is parallel to (1) and arranged along the circumference of the rotating body (2).

In this case, in order to measure the angular position in the present invention, a regular code applied to the shape of a triangle geometrically is referred to as a triangle code without using a conventional quadrature interpolation code. The fine angle is detected by itself, and the code combined in this way is called a fuse-random code & triangle code.

Referring to the operation of the digital optical angle sensor according to the present invention configured as described above are as follows.

First, the fuse-random code and the triangle code of the grating element part 3 in the digital optical angle sensor are parallel with the rotation axis 1 of the rotating body 2 together with the line image sensor of the sensing part 4 so that the rotating body It is engraved while being arranged along the circumference of (2).

Then, the detector 5 in the sensing unit 4 detects the displacement signal by measuring data represented by the fuse-random code and the triangle code of the grating element unit 3 using a line image sensor or a CCD image sensor. Then, the detected displacement signal is transmitted to the A / D converter 6.

Subsequently, the A / D converter 6 converts the displacement signal detected by the detector 5 into a digital signal and transmits the converted signal to the processor 7.

Then, the processor 7 detects the curse angle from the digital signal converted by the A / D converter 6, that is, the digital signal by the fuse-dow random code, and detects the fine angle from the digital signal by the triangle code, respectively. Then, each of the detected cues and fine angles is combined to finally measure the angular position.

Referring to the above operation in more detail, Figure 3 is a view showing the shape of the code detected by the sensing unit 4 in the digital optical angle sensor according to the present invention, as shown in FIG. The fuse-random code and the triangle code grating on the surface are detected by the line image sensor of the detector (5), which uses the line image sensor so that no matter where the fuse-random code representing the same data is detected, Is the same and can be easily measured.

On the other hand, measuring the fine angle is determined by the length of the grating portion of the triangle cord, i. E. The portion of the 't' interval of FIG.

The part with 't' spacing is detected by the line image sensor, but is not the actual angle position.

Therefore, the present invention makes it easy to find a point to be measured by comparing the vertical lengths according to the horizontal lengths stored in the look-up table according to the lengths of the 't' intervals. .

In other words, the width of the part with the interval 't' is the width of the part with the interval 't' compared to the look-up table that stores the vertical length of the 't' interval for each angle position. The angle position according to, i.e., the fine angle can be known.

On the other hand, in the present invention, the exact angular position can be detected when the fuse-random code and the triangle code grating on the actual metal (rotary body) surface are linearly engraved, and the triangle code is linear compared to the fuse-random code. Because of the high probability of not being engraved, the error may occur.

Therefore, the triangle code part compensates for an error that occurs when the inclination is lowered, that is, the greater the length displacement amount of 't' according to the displacement of the detection point, is engraved on the metal. Therefore, the lower the slope, the greater the change in the length of 't' for each detection point, thereby reducing the probability of error.

For example, by grating a metal with a radius of 60 mm to a fuse-random cord of 3 mm in length, it is possible to engrave 125 fuse-random cords, where the custom angle resolution represented by one code is 2.88 degrees, but with a triangle code added to it, one pixel (Pixel) can be detected with a CCD line image sensor with 7μm * 7μm, which allows higher accuracy. When 1 pixel represents 7 μm * 7 μm, the vertical length of 3 mm of the triangle code can represent 429 pixels, so the 2.88 degree is divided into 429 equal parts.

In this way, the precision that a pixel can represent is better than 2.88 degrees and is accurate to 0.006713 degrees. In other words, the precision of the detection point is made accurate to 7 m * 7 m corresponding to one pixel. Since the resolution required for digital optical angle sensors is less than 0.01 degrees, the 0.006713 degree would theoretically meet the needs.

As described above, the present invention measures the data represented by the fuse-random code and triangle code engraved on the metal surface through the line image sensor in the detection unit to detect the curse angle and fine angle, and then the curse angle and fine angle By detecting the accurate angular position by combining the effect of being able to accurately measure the absolute rotation angle of the rotating body. Accordingly, by applying the angle sensor according to the present invention in the EPS system it is possible to measure the accurate and high degree of absolute angular displacement of the steering shaft.

Claims (5)

A grating element portion consisting of a fuse-random cord engraved on the surface of the metal rotor rotated about the rotation axis to detect the curse angle and a triangle cord engraved on the surface of the metal rotor to detect the fine angle; A detector for detecting a displacement signal of the grating element portion using a line image sensor or a CCD image sensor as a light emitting element and a light receiving element, an A / D converter for converting the displacement signal detected by the detector into a digital signal, and the A / A digital optical angle sensor, comprising: a detector configured to detect a curse angle and a fine angle from a digital signal converted by a D converter, and combine the same to finally measure an angular position. The method of claim 1, A line image sensor as the detector in the sensing unit, a fuse-random code and a triangle cord of the grating element unit are parallel to the rotation axis of the metal rotating body and are engraved while being arranged along the circumference of the metal rotating body. sensor. The method according to claim 1 or 2, The fuse-random cord and triangle cord of the grating element portion are linearly etched on the surface of the metal rotating body, and in the case of the triangle cord, the inclination is lowered so as to compensate for an error occurring when being etched in the rotating metal. Digital optical angle sensor, characterized in that. The method of claim 1, The processor in the sensing unit detects a curse angle from a digital signal by a fuse-doubt random code converted by the A / D converter, and detects a fine angle from the digital signal by a triangle code converted by the A / D converter. And then combining each detected cue angle with a fine angle to finally measure the angular position of the digital optical angle sensor. The method according to claim 1 or 4, When the processor in the sensing unit detects a fine angle, the sensing unit is arranged at an arbitrary interval according to each angle position by a horizontal length of a portion of the triangle code detected by a line image sensor as a detector in the sensing unit. And a fine angle according to the horizontal length of the part spaced at random intervals as compared with the look-up table storing the vertical length.