JP2000009420A - Position measuring instrument - Google Patents

Abstract

PROBLEM TO BE SOLVED: To shorten the response time of a position measuring instrument which finds the position of an object in two-dimensional directions by shortening the measuring time of the instrument and, at the same time, to make the mechanical or optical constitution of the instrument simpler. SOLUTION: The position measuring instrument detects the position of an object by scanning the object in X-direction with a light beam P having a longer cross section in Y-axis direction. Then, the instrument rotates the light beam P around its optical axis and again detects the position of the object by scanning the object in the Y-direction with the light beam P having a longer cross section in the X-axis direction. Then the instrument confirms the position of the object by verifying the distance information of the object in each direction as shown in the figure.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

[0001] The present invention relates to a position measuring device. In particular, the present invention relates to a position measurement device that projects and scans a light beam toward a detection area and measures the position of an object in a two-dimensional direction.

[0002]

2. Description of the Related Art As a position measuring device (distance measuring device) capable of measuring a distance and a position to an object in a two-dimensional direction, a light beam emitted from a light projecting unit is directed two-dimensionally toward a detection area. What is scanned is generally used. FIG. 2 to FIG. 3 schematically show a distance measuring method of such a position measuring device.

Now, as shown in FIG. 1, the detection area (scanning field of view) of the position measuring device is in the main scanning direction (hereinafter, referred to as the scanning field).
In the sub-scanning direction (hereinafter, referred to as X direction)
(Referred to as the Y direction), and it is assumed that one object A is X
The direction object number (hereinafter referred to as Xn) = 3, the Y direction object number (hereinafter referred to as Yn) = 5 exists at a distance of 50 m, and another object B is 25 m at Xn = 8 and Yn = 9. Let's consider the case where they exist at a distance of.

In a conventional position measuring apparatus, as shown by an arrow in FIG. 2, a light beam P having a light beam cross section indicated by oblique lines is raster-scanned. That is, the two-dimensional detection area is raster-scanned by sub-scanning in the Y direction each time the main scanning is performed once in the X direction. Then, the presence or absence of an object and the distance to the object are sequentially measured in each of the divided areas. For example, assuming that reflected light can be received from the light beam P projected in the direction of the circle C in FIG. 2, the position measurement device obtains the distance to the target in that direction.

Then, as shown in FIG. 3, the direction in which the object exists is specified by the X-direction area number Xn corresponding to the main scanning direction and the Y-direction area number Yn corresponding to the sub-scanning direction. Xn, Yn) correspond to the distance to the object. For example, assuming that the distance to the object at Xn = 3 and Yn = 5 is 50 m and the distance to the object at Xn = 8 and Yn = 9 is 25 m, this detection result will be a square as shown in FIG. Is mapped on the diagram of the shape.

[0006]

However, in such a position measuring apparatus, it is necessary to perform a sub-scan for each main scan, so that a raster scan of a light beam in a two-dimensional direction is required. When the number of divisions of the sub-scanning area is n (usually set to 10 or more), n times of scanning time is required as compared with the one-dimensional scanning of only the main scanning, and the response until the measurement result is output is required. There was a problem that time was long.

In such a position measuring device, a polygon mirror for the main scan and a polygon mirror for the sub-scan are required, which makes it difficult not only to reduce the size of the position measuring device but also to adjust the timing of the main scan and the sub-scan. Must be synchronized, and the structure of the position measuring device has been complicated.

The present invention has been made to solve the above technical problems, and has as its object
It is an object of a position measuring device for obtaining a position of an object in a dimensional direction to shorten a measurement time and shorten a response time. Another object of the present invention is to simplify the mechanical or optical configuration of such a position measuring device.

[0009]

DISCLOSURE OF THE INVENTION A position measuring apparatus according to the present invention emits and scans a light beam from a light projecting unit toward a detection area, receives a light beam reflected by the object by a light receiving unit, and detects the position of the object. In the position measurement device for determining, the light projecting unit for projecting a light beam having a long cross-sectional shape in one direction, means for rotating the longitudinal direction of the cross section of the light beam emitted from the light projecting unit, Means for changing the one-dimensional scanning direction of the light beam in accordance with the rotation angle in the direction of the longitudinal axis of the cross section, and receiving reflected light by the light beam scanned in two or more one-dimensional scanning directions and obtaining distance information in each scanning direction. Determination processing means for determining the position of the object in the two-dimensional direction of the detection area by comprehensively determining;

The position measuring apparatus of the present invention obtains the position of a target object in a two-dimensional direction by collating and comprehensively judging distance measurement results obtained by light beams scanned in two or more one-dimensional scanning directions. Therefore, the position of the object in the two-dimensional direction can be detected with a small number of scans (at least two times).

Accordingly, since the number of times of scanning with the light beam is reduced, the response time until the measurement result is output can be extremely shortened, and the response until the measurement result is obtained can be improved. Further, the mechanical configuration and the optical configuration of the position measuring device can be simplified.

Further, when the determination processing means cannot determine the position of the object from the distance information in each of the scanned scanning directions, the direction of the light beam cross section and the one-dimensional scanning direction are further determined. If the distance is changed and the light beam is scanned to obtain new distance information, the position of the object can be determined. In addition, since the number of light beam scans is increased as needed, the number of light beam scans can be minimized, and the measurement time can be minimized. Moreover, the reliability of the position measurement device that detects the position of the target object can be improved.

[0013]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The position measuring device of the present invention may be capable of outputting only the position of an object in a two-dimensional area, but in the following embodiments, the position of the object ( An example in which the two-dimensional direction and the distance are output will be described. FIG. 4 is a schematic block diagram showing the configuration of the position measuring device 1 according to one embodiment of the present invention. The position measuring device 1 includes a light projecting unit 2, a light projecting unit driving circuit 3, an optical axis rotating unit 4, an optical scanning unit (scanner) 5, a scanning direction control unit 6, a scanning direction detecting unit 7, a light receiving unit 8, a distance, Measuring unit 9,
It comprises a synthesis processing unit 10. The light emitting unit 2 includes a light emitting element such as a semiconductor laser element (LD) or a light emitting diode (LED). When the light emitting element is driven by the light emitting unit driving circuit 3,
The light projecting unit 2 emits a light beam P having a long light beam cross section in one direction. Light beam P with a long cross section in one direction
In order to emit light from the light projecting unit 2, an optical element such as a cylindrical lens may be provided in the light projecting unit 2. Alternatively, a plurality of light emitting elements may be linearly arranged. The optical axis rotating means 4 rotates the direction of the major axis of the cross section of the light beam P emitted from the light projecting unit 2. As a method of rotating the direction of the major axis of the cross section of the light beam P, the light projecting unit 2 may be mechanically rotated around the optical axis, and the light beam P emitted from the light projecting unit 2 may be illuminated by optical means. It may be rotated around an axis.

The light scanning unit 5 reflects the light beam P emitted from the light projecting unit 2 to scan the light beam P emitted toward a predetermined detection area in a one-dimensional direction. For example, it is composed of a polygon mirror and a galvanometer mirror. The scanning direction control means 6
The optical scanning unit 5 functions to change the one-dimensional scanning direction of the light beam P by the optical scanning unit 5. The optical scanning unit 5 scans the light beam P in a direction perpendicular to the longitudinal direction of the cross section thereof at all times.
The scanning direction of the light beam P is controlled. The scanning direction control means 6 may be a means for mechanically rotating the optical scanning unit 5 or, when the optical scanning unit 5 is formed by a galvanomirror, electrically control the vibration direction of the galvanomirror. You may do so. Further, the optical axis rotating means 4 and the scanning direction control means 6 may be separately configured, but can be realized with a simple configuration by mechanically rotating the position measuring device 1 by one rotating mechanism. it can. At this time, the part to be rotated by the rotation mechanism may be at least the light projecting unit 2 and the optical scanning unit 5 or the entire position measuring device 1 (light receiving unit) except for the optical axis rotating unit 4 and the scanning direction control unit 6. 8 may be stationary).

Here, the light projecting operation in the position measuring device 1 using a semiconductor laser element as a light emitting element will be specifically described with reference to FIG. The semiconductor laser element in the light emitting unit 2 emits a pulse light every 50 μsec by the light emitting unit driving circuit 3. On the other hand, the optical scanning unit 5 sweeps the light beam P in one direction at a period of 100 msec over a measurement range of 200 mrad. Since the light beam P emits light every 25 μsec, the semiconductor laser element emits 2,000 times in 10 msec of one scan, and the distance measurement of 2,000 pulses is performed. Of the 2000 pulses in one scan, 1600 pulses from 201 to 1800 are used for distance measurement, and distance measurement is not performed in the end point areas (pulses 1 to 200 and pulse 1801 to 2000). 1600 pulses (201 to 1) used for distance measurement
The 800th pulse) is divided into 80 regions every 20 pulses, and the distance measurement results for 20 pulses (for one region) are averaged to obtain the distance to the target. Note that the number of pulses is merely an example, and for example, may differ between the X-direction scan and the Y-direction scan.

The scanning direction detecting section 7 detects the one-dimensional scanning direction (scanning direction area number) of the light beam P by the optical scanning section 5 with reference to the light beam P in the end point area. (For example, X-direction area numbers Xn, Y) corresponding to the light beam scanning direction detected by
The direction area number Yn) is transmitted to the distance measurement unit 9.

The light beam P emitted from the light projecting section 2 and scanned by the optical scanning section 5 is projected toward a front detection area,
After being reflected by the object, the light returns to the position measuring device 1 and is received by the light receiving unit 8. The light receiving section 8 includes a light receiving element such as a photodiode (PD) or a phototransistor and a light receiving circuit (amplifying circuit). The distance measuring unit 9 compares the light receiving signal output from the light receiving unit 8 with a predetermined threshold voltage, and determines that the light receiving unit 8 has received the light beam P when the light receiving signal is equal to or higher than the threshold voltage. Then, the distance to the target is calculated based on the delay time τ from the light projection timing to the light reception timing. That is, if the distance to the object is L and the speed of light is c, the delay time is τ = 2L / c, so the distance L to the object is obtained from the delay time τ. Further, since the distance measuring unit 9 receives the scanning region number (the scanning direction of the light beam P) from the scanning direction detecting unit 7, the distance information composed of the pair of the scanning region number and the measured distance is combined with the combining processing unit 10 Output to

Upon receiving the distance information from the distance measurement unit 9, the synthesis processing unit 10 stores the distance information for each scan in a memory (not shown), and stores the distance information for a plurality of scans in a plurality of directions. The position and distance of the target object in the two-dimensional direction are comprehensively determined based on and output. In addition, the synthesis processing unit 10 controls the optical axis rotating unit 4, and when the distance information for one scan is received from the distance measuring unit 9, the optical axis rotating unit 4 rotates the optical axis direction of the light beam P. Accordingly, the scanning direction of the light beam P is also changed.

Next, a method of detecting the distance of the object in the two-dimensional direction by several one-dimensional scans in the position measuring device 1 having the above configuration will be described with reference to FIGS. Now, it is assumed that the objects A and B exist at the same position and the same distance as described in the conventional example, as shown in FIG. In the position measuring device 1, as shown in FIG. 7, the light beam P is emitted from the light projecting unit 2 with the longitudinal direction of the cross section of the light beam P parallel to the Y direction. The beam P is scanned in the X direction. At this time, an object is detected at a position at a distance of 50 m when the X-direction area number Xn = 3, and the distance is 25 when the X-direction area number Xn = 8.
It is assumed that an object is detected at the position of m. This detection result is stored in the memory in the synthesis processing unit 10. After that, the synthesis processing unit 10 outputs a signal to the optical axis rotating unit 4,
As shown in FIG. 8, the light beam P is emitted from the light projecting unit 2 by rotating the optical axis such that the major axis direction of the cross section of the light beam P is parallel to the X direction. Accordingly, the light scanning unit 5 causes the light beam P to scan in the Y direction. At this time, the Y direction area number Y
It is assumed that an object is detected at a position with a distance of 50 m when n = 5, and an object is detected at a position with a distance of 25 m with Y-direction area number Yn = 9. This detection result is also stored in the memory in the synthesis processing unit 10.

The synthesis processing unit 10 comprehensively determines the distance information obtained as a result of the one-dimensional scanning in these two directions, and obtains the position and distance of the object in the two-dimensional direction. That is, in the present case, the object at a distance of 50 m is Xn
= 3 and Yn = 5, the distance is 50 in the direction of (Xn, Yn) = (3, 5) in the two-dimensional area.
It can be seen that the target exists at the position of m. Similarly, an object at a distance of 25 m is detected at Xn = 8 and Yn = 9, so that (Xn, Yn) =
It can be seen that the target exists at a position at a distance of 25 m in the direction (8, 9).

In other words, (Xn, Yn) = (3, 3)
In the direction of 9) or the direction of (Xn, Yn) = (8, 5),
Since the distance of the object is mismatched, it is determined that no object exists in this direction. This determination result is mapped on a grid-like diagram as shown in FIG.

Next, as shown in FIG. 10, two objects D and E exist side by side in the X direction, and the direction of each of the objects D and E is (Xn, Yn) = (3, 9). , (Xn, Yn) =
(8, 9). In this case, as shown in FIG. 11, in the X-direction scanning, an object is detected at a distance of 50 m when Xn = 3, and an object is detected at a distance of 25 m when Xn = 8. Next, in the Y-direction scanning, 25 m with Yn = 9
And an object is detected at a distance of 50 m. Also in this case, after the distance information in both scanning directions is stored in the synthesis processing unit 10, the distance information is comprehensively determined. As a result, as a result of collation of the distances of the objects, the synthesis processing unit 1
0 indicates that the object exists at a distance of 50 m when (Xn, Yn) = (3, 9) and 25 when (Xn, Yn) = (8, 9).
It is determined that the object exists at a distance of m.

Next, a case where the position of the object cannot be determined by two one-dimensional scans will be described. For example, as shown in FIG. 12, an object F exists at a distance of 50 m in the directions of Xn = 3 and Yn = 5, and an object G exists at a distance of 50 m in the directions of Xn = 9 and Yn = 9. Think about it.
In this case, as shown in the flowchart of FIG. 14, the synthesis processing unit 10 scans in the X direction to accumulate distance information (S1), and then scans in the Y direction to accumulate distance information (S2). Then, it is checked whether there is a plurality of pieces of distance information of the same distance (S3). If there is no distance information of the same distance, the combining processing is performed and the presence of the object is determined from the distance information of the X-direction scan and the distance information of the Y-direction scan. A direction and a distance are determined (S5). On the other hand, if there is distance information of the same distance among the distance information of the X direction scan and the Y direction scan (S3), the optical axis rotation unit 4 rotates the optical axis direction of the light beam P, and Scan in a direction that does not coincide with the Y direction, for example, an oblique 45 ° direction (oblique scan)
(S4). Then, the distance information of the X-direction scan,
The distance information of the Y-direction scan and the distance information of the oblique scan are combined to determine the direction and distance in which the object exists (S5).

Thereafter, it is determined whether or not the direction and the distance of the object are determined from the distance information (S6). If not determined, the direction of the major axis of the cross section of the light beam P and the scanning direction are further rotated in different directions. Then, distance information is obtained (S4). Then, the direction and the distance where the target object exists are obtained from the distance information stored again (S5). When the direction and the distance of the object are determined in this way (S6), the determined distance measurement data is output, and one distance measurement process ends.

More specifically, referring to FIG. 12, in the X-direction scanning, an object is detected at a distance of 50 m when Xn = 3 and Xn = 9. In the Y direction scanning, Yn
= 3 and Yn = 9, the object is detected at a distance of 50 m.
Therefore, as a result of collating the distance information obtained by the two one-dimensional optical scans, as shown in FIG. 13, (Xn, Yn) = (3, 5) (Xn, Yn) = (9, 5) ( Xn, Yn) = (3, 9) Four candidates of (Xn, Yn) = (9, 9) are given, and which of these four regions is the direction in which the true object exists is determined by: I can't decide.

In the case where the same distance exists as described above, as shown by hatching in FIG.
As a result, the light beam P is rotated so that the long-axis direction of the section becomes oblique, and the light beam P also scans in a direction orthogonal to the long-axis direction of the cross section. According to the oblique scanning, it is assumed that the target exists at a position of 50 m in the directions of the oblique area numbers θn = 5 and θn = 6. When the result of the oblique scanning is compared with the directions that have become the four candidates, a position at 50 m in the direction of (Xn, Yn) = (3, 5) (Xn, Yn) = (9, 9) It can be seen that the object exists.

Here, the case in which the number of objects is two has been described.
The determination process at 0 is only slightly complicated, and it is possible to detect the distance of the target in the two-dimensional direction with several (minimum two) scans.

[Brief description of the drawings]

FIG. 1 is a diagram showing an arrangement (direction and distance) of an object.

FIG. 2 is a diagram for explaining a light beam scanning method of a position measuring device using a conventional raster scan method.

FIG. 3 is a diagram showing a measurement result by the position measuring device according to the first embodiment;

FIG. 4 is a block diagram showing a configuration of a distance measuring device according to an embodiment of the present invention.

FIG. 5 is a diagram illustrating one scan of a light beam (laser pulse) in the position measuring device according to the first embodiment.

FIG. 6 is a diagram illustrating an example of an arrangement of an object.

FIG. 7 is a diagram showing an X-direction scan of the object shown in FIG. 6 and a result of distance detection.

FIG. 8 is a diagram showing a Y-direction scan of the object shown in FIG. 6 and a result of distance detection.

9 is a diagram showing a result obtained by synthesizing the distance information of the X-direction scan of FIG. 7 and the Y-direction scan of FIG. 8;

FIG. 10 is a diagram showing another arrangement of an object.

11 is a diagram illustrating a result of distance detection of an X-direction scan and a Y-direction scan with respect to the target object illustrated in FIG. 10 and a result of a synthesis process of the distance information.

FIG. 12 is a diagram showing still another arrangement of an object.

13 is a diagram illustrating a result of a distance detection result of an X-direction scan and a Y-direction scan with respect to the object illustrated in FIG. 12 and a result of a synthesis process of the distance information.

FIG. 14 is a flowchart showing a method of determining the direction of an object in the position measuring device.

FIG. 15 is a diagram illustrating a result of performing a combining process on the distance detection result of the oblique scan with respect to the target object illustrated in FIG. 12 and the distance information.

[Explanation of symbols]

 Reference Signs List 2 Projection unit 4 Optical axis rotation unit 5 Optical scanning unit 6 Scanning direction control unit 7 Scanning direction detection unit 8 Light reception unit 9 Distance measurement unit 10 Synthesis processing unit P Light beam

 ──────────────────────────────────────────────────続 き Continued on front page F term (reference) 2F065 AA04 DD02 DD06 FF33 GG04 GG07 GG14 HH05 JJ15 LL08 LL13 LL15 MM16 UU06 5J084 AA01 AA04 AA05 AD01 AD03 BA03 BA06 BA16 BA34 BA36 BA49 BA50 BB07 BB26 BB05

Claims (2)

[Claims] 1. A position measuring device for projecting and scanning a light beam from a light projecting unit toward a detection area, receiving a light beam reflected by the object by a light receiving unit, and finding a position of the object. A light projecting unit for projecting a light beam having a long cross-sectional shape, means for rotating a cross-sectional major axis direction of a light beam emitted from the light-projecting unit, and a rotation angle of the light beam in a cross-sectional major axis direction. Means for changing the one-dimensional scanning direction of the light beam by receiving the reflected light of the light beam scanned in two or more one-dimensional scanning directions, and comprehensively determining distance information in each scanning direction to detect the detection area. And a determination processing means for determining the position of the object in the two-dimensional direction. 2. If the determination processing means cannot determine the position of the object from the distance information in each scanning direction, the direction of the light beam is further changed in the longitudinal direction of the cross section and in the one-dimensional scanning direction. 2. The position measuring device according to claim 1, wherein the light beam is scanned to obtain new distance information.