JPH07120241A - Method and device for detecting position of object - Google Patents

Abstract

PURPOSE:To make it possible to perform the highly accurate angle detection by obtaining the difference, sum and ratio of light intensities which are received by a plurality of light receiving elements that has the same light reception characteristics and the same angle in a reverse direction from the center. CONSTITUTION:The respective orientation directions 10 and 11 of light receiving elements 3 and 4 are inclined in a manner to form the same angle to and opposite to the center direction 12 between two light receiving elements 3 and 4. The light reception intensity through an optical path 8 or 9 is determined based on the light reception characteristics of the element 3 or 4, and the intensity is represented as an angular function showing the incident direction from an object 1 against the center direction 12. A calculation circuit 5 calculates the light reception intensities of the lights detected by the elements 3 and 4 so as to obtain their angles through an angle calculation circuit 6. That is, the sum A and difference B of phase difference between the light reception levels due to different directions of the elements 3 and 4 are found out, thereby obtaining the light incident angle based on the ratio B/A of the sum and difference.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method and apparatus for detecting the position of an object such as an obstacle by light.

[0002]

2. Description of the Related Art As a method of detecting the position of an object by light, there is a method shown in FIG. The one shown in FIG. 8 is
It has a light emitting element 2 for irradiating the object (obstacle) 1 with light and a light receiving element 19 for receiving the light reflected from the object 1.
Among these, the light receiving elements 19 are arranged side by side in different directions so that the direction thereof gradually changes, and among the plurality of light receiving elements 19, the light receiving element 19 that is most directly opposed to the reflected light at the light receiving level. Detects the light receiving element 19
Is determined as the incident angle.

[0003]

However, the above-mentioned FIG.
In the position detection by the light receiving element 19, the angle data obtained by the light receiving element 19 can obtain only the discrete value for each angular step corresponding to the difference in the tilt angle between the adjacent light receiving elements 19, so that the angle detection can be performed with high accuracy. I can't. In addition, a large number of light receiving elements 19 are needed to obtain highly accurate angle data.

It is an object of the present invention to provide a position detecting method and apparatus capable of highly accurate angle detection without using a large number of light receiving elements.

[0005]

Means for Solving the Problems The present invention that achieves the above-mentioned object is as follows: (1) The light applied to an object is detected by two light-receiving elements tilted at the same angle, and the light-receiving elements are respectively detected. A characteristic is that the sum A of the detected light receiving levels is taken and the difference B is taken, and the light incident angle is obtained based on the ratio B / A of the sum and the difference.

(2) Two light-receiving elements which are tilted to the left and right about the center direction by the same angle, a light-receiving level calculating circuit for the detection light of each light-receiving element, and a sum A of light-receiving levels by this calculating circuit. And an angle calculation circuit that obtains a light incident angle at a ratio B / A of the difference B.

[0007]

By using the directivity of the two light receiving elements facing different directions with respect to the incident light, the light receiving level corresponding to the intensity of the light corresponding to the incident angle at each light receiving element is detected, and the light receiving level of each of these light receiving levels is detected. By taking the difference and taking the sum of the received light levels, it is possible to calculate the incident angle in the angle detectable range while canceling the strength of the received light level due to the perspective of the reflecting object by the ratio of this difference and the sum. The position can be detected.

[0008]

Embodiments of the present invention will now be described with reference to FIGS. FIG. 1 shows the overall configuration of the first embodiment, and light is emitted from a light emitting element 2 toward an object (obstacle) 1 as in FIG. The light reflected by the object 1 is incident on the two light receiving elements 3 and 4 having the same light receiving characteristics. The two light receiving elements 3 and 4 are arranged in different directions. That is, a direction (center direction) 12 passing through the center between the two light receiving elements 3 and 4
On the other hand, the center directions (directing directions) 10 and 11 of the light receiving element 3 and the light receiving element 4 are inclined at the same angle and opposite to each other.

In this case, the light receiving characteristics of the light receiving elements 3 and 4 are
As shown in FIG. 2, the efficiency of conversion of light from 0 °, which is the central direction (direction), into an electric signal is highest, and the received light intensity is 1
Has become. For example, the incident light at the angle of the path 9 in FIG. 2 has a received light intensity of 0.75. Therefore, the light receiving intensity of the light paths 8 and 9 is determined from the light receiving characteristic of the light receiving element 3 or 4, and this light receiving intensity is expressed as a function of the angle formed by the incident direction from the object 1 with respect to the center direction 12.

The calculation circuit 5 connected to each of the light receiving elements 3 and 4 calculates the received light intensity of the light detected by the light receiving elements 3 and 4.

The two calculation circuits 5 are connected to the angle calculation circuit 6. In the angle calculation circuit 6, as shown in FIG. 3, the sum A (broken line) of the light receiving level based on the light receiving characteristic of the light receiving element 3 (dashed line) and the light receiving level based on the light receiving characteristic of the light receiving element 4 (dashed line). Difference B (solid line)
Is calculated, and the angle is calculated from the ratio B / A of the sum and the difference. That is, the sum and the difference of the phase difference of the light receiving level shown in FIG. 3 based on the difference in the direction of the light receiving elements 3 and 4 are taken. The angle from the center direction is obtained. In this case, the ratio B / A of the sum A of the left and right received light intensities and the difference B is a range corresponding to the incident angle on a one-to-one basis. In order to adjust the phase difference between the levels from the shape of the light receiving characteristic shown in FIG. 2, it is necessary to determine the tilt angles of the light receiving elements 3 and 4. Further, as shown in FIG. 4, if the distance between the light receiving elements 3 and 4 is too large, the incident angles θ ₁ ′ and θ ₂ ′ change and an error occurs.

FIGS. 5 and 6 show the level difference between the object 1 and the light receiving element when the object 1 is near and far. That is, case 1 is near and case 2 is far, and the level of the light receiving element is high near and low near. Therefore, as shown in FIG.
In case B ', the slope of the characteristic changes between Case 1 and Case 2 as shown by the solid line and the alternate long and short dash line. Further, the level sum AA ′ in this case is also high near (one-dot chain line) and far away (two-dot chain line) as shown in FIG. 6, and as a result, by adding the perspective of the object 1, as shown in FIG. The ratio B / A (B '
By taking / A '), the influence of the distance of the object 1 can be eliminated. Thus, the relationship between the ratio B / A and the angle is stored in advance, and the object 1
The angle of the incident light from can be calculated.

FIG. 7 shows a second embodiment, in which two sets of light receiving elements for angle detection of the above-mentioned first embodiment are installed with an interval d between them, and the angle of incidence is detected by each of the angle detectors 13 and 14. θ
₁ and θ ₂ are obtained. As a result, the distance L in FIG. 7 is obtained by the following equation [Equation 1].

[0014]

[Equation 1]

[0015]

As described above, according to the present invention, the incident angle can be obtained by the difference in the light intensity between the two light receiving elements, and the variation in the intensity of the light can be eliminated by the sum of the intensities. You can get the angle.

[Brief description of drawings]

FIG. 1 is a block diagram showing the overall configuration of an embodiment.

FIG. 2 is a light receiving characteristic diagram of a light receiving element.

FIG. 3 is a characteristic diagram of a light receiving level and an angle.

FIG. 4 is a diagram showing a change in an incident angle of a light receiving element interval.

FIG. 5 is a characteristic diagram when the target is near and far.

FIG. 6 is a characteristic diagram when the target is near and far.

FIG. 7 is a configuration diagram of another embodiment.

FIG. 8 is a configuration diagram of a conventional example.

[Explanation of symbols]

 1 Obstacle 2 Light emitting element 3 Light receiving element (right) 4 Light receiving element (left) 5 Light receiving power calculation circuit 6 Angle calculation circuit 7 Angle output 8 Path (right) 9 Path (left) 10 Directional direction (right) 11 Directional direction ( Left) 12 Center direction 13 Angle detector (right) 14 Angle detector (left) 19 Light receiving element

Claims (2)

[Claims] 1. The light applied to an object is detected by two light receiving elements tilted at the same angle, the sum A of the light receiving levels detected by the respective light receiving elements is taken, and the difference B is taken. And an object position detection method for obtaining a light incident angle based on the ratio B / A of the difference. 2. A light receiving element tilted to the left and right at the same angle about a center direction, a light receiving level calculating circuit for detection light of each of the light receiving elements, and a sum A of light receiving levels by the calculating circuit and a difference. An object position detecting device, comprising: an angle calculation circuit that obtains B and obtains a light incident angle at a ratio B / A.