JPH03163301A - Position detecting method - Google Patents

Abstract

PURPOSE:To make it possible to detect the position of a spot light by providing a spot-position detecting sensor at a position which is different from the axis of a light projecting beam, removing the secondary reflecting light having the large amount of the spot, and selecting the signal having the weakest amount of light. CONSTITUTION:A incident light beam 2 projects a spot light. A lens and a spot position detecting sensor 5 are provided at a position A thus focusing an image. When the image is not formed on the sensor 5 at the position A, a part of a body to be detected 4 forms a dead angle between a point M of the spot light and the sensor 5. At this time, the positions of the lens and the sensor 5 are turned and changed with the beam 2 as an axis. The lens and the sensor 5 are moved to a position where the spot light on the body to be detected 4 is not shielded with another body. A formed image M' can be obtained on the sensor 5 at a position B. The spot light is shielded at a position A, and the signal to be detected is not detected. Then, the peak point of the amount of the light of the detected signal at the point B appears as the formed image. At this time, (a) and (b) are synthesized, and the synthesized output (c) is obtained. This operation is performed at a plurality of places, and the output signal whose amount of light has the smallest value is adopted.

Description

DETAILED DESCRIPTION OF THE INVENTION (Industrial Technical Field) The present invention relates to a position detection method for accurately detecting the shape and position of an object from a received light spot image in which blind spots, secondary reflections, etc. have occurred. (Prior art) Conventionally, triangulation using light has been used to detect the height of the surface of an object using light! It is often detected by photosection (hereinafter referred to as photosection). As shown in FIG. 7, a light beam is irradiated onto the surface of the object 2o from directly above, and the reflected light is imaged on the position detection sensor 22 by the lens 2l. It was designed to detect. However, in this method, if the surface of the object 2o is a glossy surface, in the case of the object 23 as shown in FIG.
Secondary reflection from the inclined surface occurs and the position detection sensor 2
Since multiple spots are imaged on 2, there was a drawback that the true height A of the object was not detected, but the secondary reflection R resulted in the detection of a height R'' that was lower than the actual height. , as shown in Fig. 9, the spot of the light beam sometimes becomes a blind spot of another object 24, making detection impossible. 63-22
``Shape mj &device'' shown in Publication No. 241 has been proposed. As shown in Figure 10, this method attempts to selectively extract the light-cut IFr line by taking advantage of the fact that the abnormal reflection occurs below the slit emission line, since the abnormal reflection occurs on the surface of the measured object. It was something to do. (i[] to be solved by the invention) However, in this method, for example, as shown in FIG. If there is, the light beam is A
A spot image A' is reflected at the point and formed on the position detection sensor 22 via the lens 21, and a spot image A' is formed on the inclined surface 26.
Next, reflection occurs and another spot image R' is formed. This R
The image formed at ' is seen at the intersection point R'' of the incident light of the light beam and the reflected light from the reflection point R, and the intensity of the light is large and it is the true bright spot A.
This has the disadvantage that it is difficult to apply when the target object has a complex shape.

The present invention has been made in view of the above-mentioned circumstances, and its purpose is to provide a position detection method that does not cause false detection due to secondary reflections, blind spots, etc. even if the target object has a complex shape. This is L's. (Means for Solving the Problems) In order to achieve the above object, the position detection method of the present invention projects a light beam onto an object to be detected, and reflects the projected light beam by the object to be detected. In a position detection method that receives light and detects a change in the position of a receiving spot of reflected light,
A spot position detection sensor for detecting the moving direction of the light receiving boat/light is arranged at a position relative to the axis of the light beam for projection, and the spot position detection sensor detects the direction of movement of the light receiving boat/vehicle. This system is characterized in that a predetermined position detection sensor is selected based on the positional information of the light receiving spot of the detected object, and the position of the detected object is detected one step. (Function) In the position detection method as described above, position detection sensors for detecting the direction of movement of the light receiving spot are provided at different positions with respect to the axis of the light emitting beam, and the spot position sensors are The detection output of each information is combined, and the signal with the weakest light amount is selected by excluding the secondary reflected light with a large amount of spot light, so the spot light position can be detected accurately. (Embodiment) An embodiment of the present invention will be explained below with reference to FIGS. 1 to 4. In light cutting, as long as the angle of incidence of the reflected light on the spot position detection sensor is constant with respect to the direction of the light beam projection, it is possible to rotate the position of the spot position detection sensor around the projection light beam. , it is possible to detect the same spot light position. Here, if a line type sensor is used as the spot position detection sensor, the position of the spot light hitting the object to be detected will be on the incident light beam unless there is a blind spot or secondary reflection, and the position of the line type sensor and this human light beam will be By arranging the line sensor at a position where the line surface becomes flat, the spot light is always focused on the line sensor. If secondary reflection occurs, the secondary reflection spot light will be imaged on the line sensor only when the secondary reflection spot light is generated on the above-mentioned plane, and the true spot light position will be the secondary reflection spot. Accurate position detection becomes impossible due to the influence of light. However, if the position of the line sensor is rotated along with the lens around the incident light beam, the plane defined by the incident light beam and the line sensor will rotate, making it possible for the secondary reflected light to not lie on this plane. can do. That is, as shown in Figure 1,
When detecting the position of a point M on the slope 1a of the object to be detected 1, an incident light beam 2 is projected from perpendicularly above M, and a line type sensor 3 is directed to the incident light beam 2 through a lens. is at position A, and two images M' and N' are formed on the line sensor 3. This image of N' is a spot light obtained by secondary reflection of the incident light beam 2 at N. . This consists of the incident light beam 2, the image formed by the spot light at point M, M', and the image formed by the secondary reflected light Subosoto.
This means that two images M' and N' have appeared on the plane A containing '. In such a case, if the lens is rotated around the incident light beam 2 without changing the relative relationship between the line sensor 3 and only one image appears on the line sensor 3 at position B, then this Image M1 is caused by the spot light at point M. This is illustrated in Figure 2. In FIG. 2, (a) is an image formed by one line type sensor at the A position, and (b) is an image formed by the other line type sensor at the B position.
By comparing the two detected waveforms, it can be seen that the M' and M' waveforms are true spot lights. Blind spot correction can be done in the same way. In FIG. 3, the incident light beam 2 projects a spot light onto a point M, and a lens and a spot position detection sensor 5 are located at a position A to obtain an image.
When no image is formed, a part of the object to be detected 4 is a blind spot between the spot light point M and the subbond position detection sensor 5, and in this case, the lens and the spot position detection sensor 5 rotates around the incident light beam 2 to move to a position where the spot light on the object to be detected is not blocked by other objects, and an image M' is formed on the spot position detection sensor 5 at position B. be able to. As a result, as shown in FIG. 4, the detection signal at position A is not detected because the spot light is blocked, as shown in (a). Next, in the detection signal at position B, the peak point of the light amount appears as an image as shown in (middle). In this case, the above (
By combining a) and (b), the combined precept output of (C) can be obtained. By performing this operation at multiple locations and using the output signal with the smallest amount of light among the output signals, two
Next, select a sensor that does not receive reflected light. This allows blind spot correction. In this way, even if there is a blind spot, by rotating the lens around the incident light beam 2 without changing the relative relationship between the lens and the spot position detection sensor 5, erroneous detection due to the blind spot can be removed by selecting the detection waveform. be able to. The method of changing the position of the line type sensor 3 or the spot position detection sensor 5 described above involves rotating one sensor, but multiple sensors are arranged in advance around the axis of the incident light beam, and each A similar effect can be obtained by combining and selecting detected waveforms. Next, a selection method when a plurality of line type sensors or spot position detection sensors are used will be explained. If these plurality of sensors are arranged in advance at positions A and B, as shown in Fig. 3, so that blind spots are less likely to occur, then, as shown in Fig. 4, The detection symbol at position A and the detection symbol at position B can be detected simultaneously, and by combining them, the combined output shown in (C) can be easily obtained. In addition, by rotating the sensors placed at positions A and B by a certain angle around the axis of the incident light beam, the detection signals at each position are combined, and the signals to be detected are further synthesized. The object is m
Accurate position detection signals can be detected even if the position detection signal is in an s-shaped configuration. As this detection signal, the one with the least amount of light can be selected from among the output signals captured by each sensor. Generally, secondary reflection occurs and when detected by the sensor,
The light intensity of the secondary reflected spot light is larger than that of the true spot light. This is because the surface on which the spot light hits is perpendicular to the surface where the sensor and the incident beam are located, as shown in Figure 5, and the direction in which the amount of reflected light is greatest. The above-mentioned combined output signal including the sensor with the secondary reflected spot light is compared in terms of total light intensity. It is larger than other joint output signals. Based on this, if the signal with the weakest light intensity of the combined output signals is selected, accurate detection of the spot light position becomes possible. Here, a line type sensor consists of a light receiving element arranged in a long and narrow manner, and it expresses the peak value of the spot light on a straight line. The same effect can be obtained by using something like PSD) and selecting the one with the minimum combined light intensity. In addition, as a spot position detection sensor, an array sensor in which a large number of light receiving elements are arranged in a row in the direction of spot movement is used.
Array sensors are placed in multiple positions as described above,
The output signals of each array sensor are combined in a configuration that reduces the possibility of blind spots. Then, using this combined output signal, an array sensor with a small number of peak values above a certain value may be employed. In this case, as shown in FIG. 2, if the secondary reflected beam light enters, it will have a peak value in addition to the true spot position, and the resultant output signal will naturally have a plurality of peak values. By using only the peak value of the true spot light as the combined output signal without incident secondary reflected beam light, it is possible to easily and accurately determine the true spot position. In other words, this is possible by removing the influence of the secondary reflected beam from the object to be detected by employing the array sensor that has the least number of peak values among the combined output signals. The true spot position can be detected by using the array sensor described above and selecting among the output signals the one with the highest number of peak values that are greater than a certain value and that exist at the same location. The method will be explained below. The output signal of each array sensor has various peak values due to the secondary reflected beam light, and the true spot light may disappear due to blind spots. However, when each peak position of a plurality of array sensors is extracted, the probability that the peak position that occurs most often becomes the true spot position is high, and the probability increases as the number of array sensors increases. This also makes it possible to detect the true spot position.

FIG. 6 is a block diagram of a device for calculating the spot position used in each of the above-mentioned detection methods. It consists of a position detection section and a sub-position position calculation section, and the outputs of the n-row light receiving elements (spot position detection sensors) are manually input to the sub-position position calculation section 6 via the n-row line memory, and the minimum peak value,
It is manually applied to each block according to the minimum amount of light and the maximum frequency of occurrence. The output after each detection is input to a spot position calculating section to determine the true spot position, and is input to a spot position memory section and stored therein. The minimum peak value number sensor detection section, the minimum detected light amount sensor detection section, and the most frequently occurring peak position detection section in the spot position calculation section 6 are adapted to each method corresponding to the structure of the spot position detection sensor. You may take precautions.

(Effects of the Invention) As explained in detail above, the position detection method of the present invention has the following features:
In a position detection method that projects a light beam onto an object to be detected, receives reflected light of the projected light beam by the object to be detected, and detects a change in the position of a light-receiving subwoofer of the reflected light, the light-receiving spot A spot position detection sensor for detecting the moving direction of the light beam is arranged at a position relative to the axis of the emitting light beam, and the spot position detection sensor detects the light receiving spot of the object to be detected at the position of each spot position detection sensor. The feature is that a predetermined position detection sensor is selected from the position information to detect the position of the detected object, so even if the object to be detected has a complex shape, false detection due to secondary reflections, blind spots, etc. can be avoided. The advantage is that it never occurs.

[Brief explanation of the drawing]

1 to 6 show examples of the present invention, and FIG. 1 is a perspective view showing the image formation state when the sensor position is changed, and FIG.
Figures (a) and (b) are detection waveform diagrams at each sensor position, where (a) is with secondary reflection, (b) is without secondary reflection, and Figure 3 is detection for blind spot correction. A plan view showing the position, Figure 4 (a), (b), and (C) are waveform diagrams at each sensor position in Figure 3. (a) is inside the blind spot) is outside the blind spot,
(C) is a combination of (a) and (b), Figure 5 is a plan view showing the distribution of reflection intensity generated on inclined surfaces, etc., Figure 6 is a block diagram, and Figures 7 to 7 are Figure 11 shows the conventional example, and Figure 7 shows the triangle 2! ! Figure 8 shows an example of secondary reflection from a specular object, Figure 9 shows an example of a blind spot, Figure 10 shows an image formed by secondary reflection, and Figure 11 shows an example of reflection from a complex-shaped object. It is. l...Object to be detected 3...Line type sensor 5...Spot position detection sensor] Figure light intensity Figure 2 (0) 7 Figure B 8 Figure 9 Figure 11 Figure 10

Claims (1)

[Claims] In a position detection method that projects a light beam onto an object to be detected, receives reflected light of the projected light beam by the object to be detected, and detects a change in position of a light receiving spot of the reflected light, wherein the light receiving spot A spot position detection sensor for detecting the moving direction of the light beam is arranged at a position relative to the axis of the emitting light beam, and the spot position detection sensor detects the light receiving spot of the object to be detected at the position of each spot position detection sensor. A position detection method characterized by selecting a predetermined spot position detection sensor from position information and detecting the position of an object to be detected.