JPH032241B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION Field of the Invention The present invention relates to an inclination angle measurement system, and particularly to a system for measuring, for example, an angle made by a moving body with respect to a predetermined reference line.

Description of the Prior Art Various inclination angle detection devices have been proposed or realized for civil engineering machinery, agricultural machinery, and the like. However, conventional tilt angle detection sensors
Many of them have low accuracy, while those with high accuracy have the disadvantage that the equipment is large and expensive.

OBJECTS OF THE INVENTION Therefore, the main object of the present invention is to provide a completely new tilt angle measurement system that can perform highly accurate measurements with a simple configuration.

Structure of the Invention In summary, the present invention provides a light reflecting means that reflects incident light in the same direction and has a mask formed in a predetermined area of the light reflecting mirror surface, and a sharply directional light beam is emitted from an object. The object side receives the light reflected from the light reflecting means, and based on the received light output, the light scanning surface formed by the light beam is displaced so that it coincides with a predetermined reference line. let me,
At this time, the angle formed by the object with respect to the reference line is detected by detecting the amount by which the optical scanning surface is displaced by the displacement means.

The above objects and other objects and features of the present invention will become more apparent from the following detailed description with reference to the drawings.

DESCRIPTION OF THE EMBODIMENTS FIG. 1 is an external perspective view showing a corner cube as an example of a light reflecting means used in the present invention. Inside this corner cube CC, for example, there is a second
As shown in the figure, a three-dimensional combination of three mirrors 1, 2 and 3 is housed. These mirrors 1~
3 are respective reflective mirror surfaces 1a, 2a and 3a
are combined so that they are orthogonal to each other. With such a configuration, the corner cube CC has optical properties as described below.

That is, the corner cube CC reflects the incident light in the same direction as the incident direction. Now, consider the light L1 that is incident on the corner cube CC at an incident angle θ1. This incident light L1 is reflected multiple times (twice) by the light reflecting mirror surfaces 1a to 3a inside the corner cube 1, and exits from a position symmetrical to the optical axis O of the corner cube CC. At this time, the reflected light L1 is parallel to the incident light L1, and its reflection angle is equal to the incident angle of the incident light L1. Therefore, the reflected light L
1 is reflected in the same direction as the direction in which the incident light L1 has entered. This relationship holds true regardless of the angle of incidence of the incident light. For example, the incident light L2 and the reflected light L2 are parallel to each other, and the incident light L2
The incident angle of L2 and the reflection angle of reflected light L2 are both θ2
is equal to

FIG. 3 shows a mobile object V using an embodiment of the present invention.
It is a figure which shows the state where the inclination angle of is being measured. FIG. 4 is a view of the beam scanner BS from above the moving body V, and shows the scanning state of the light beam. FIG. 5 is a diagram showing the relationship between the mask MA formed on the corner cube CC and its reflected light.

First, before explaining the details of the embodiment of the present invention, the principle of the embodiment will be explained with reference to FIGS. 3 to 5.

As shown in FIG. 3, the corner cube CC is fixed in place. On the other hand, a beam scanner BS is provided at the front of the moving body V. This beam scanner BS generates a sharply directional light beam, such as a laser beam, and rotates and scans it toward the corner cube CC, as shown in FIG.

On the other hand, a mask MA such as paint or paper is applied to a predetermined area of the light-reflecting mirror surface of the corner cube CC.
is formed. In the example of FIG. 5, the light reflecting mirror surface 3a
The mask MA is formed in a fan-shaped area with a center angle of 45 degrees from one side (in addition, in the top view, a fan-shaped area with a center angle of 60 degrees). Note that the mask MA is formed so that the center and peripheral portions of the corner cube CC are exposed. Since the light incident on the part where the mask MA is formed does not hit the light reflecting mirror surface 3a,
It is not reflected in the same direction as the incident direction.

By the way, the area indicated by the dotted line in Figure 5
MA′ and MA″ are the areas shaded by the mask MA. That is, these areas MA′ and
The light incident on MA'' is once reflected by the light reflecting mirror surface, but because it hits the mask MA during the second or third reflection, it is not reflected in the same direction as the direction of the incident light.

The corner cube CC as described above is fixed at a predetermined position as shown in FIG.
It is adjusted to match X (for example, a line along the horizontal plane).

Now, the light beam from the beam scanner BS is on the fifth
Let us consider the case where the corner cube is scanned through the optical axis center 00 of the corner cube CC as shown in the diagram A→B or C→D. The light beam is A→
If scanned with B, i.e. corner cube
If the scan line on CC is upward sloping to the right with respect to the reference line XX (in FIG. 5), the scan line does not pass through any part of the mask MA or areas MA' and MA''. Therefore, at this time, the reflected light from the corner cube CC will include one wide pulse, as shown in Figure 5.On the other hand, the light beam from the beam scanner will be reflected from C→
If scanned with D, i.e. corner cube
If the scan line on CC is downward to the right with respect to the reference line X-X (in Figure 5), the scan line is
passes over MA′ and mask MA. Therefore, the reflected light from the corner cube CC at this time includes three pulses, as shown in FIG.

In the moving body V, a corner cube as described above is used.
By receiving the reflected light from CC and counting the number of pulses, it is determined whether the scanning line is upward to the right or downward to the right with respect to the reference line XX. Then, based on the determination result, the scanning plane of the light beam is rotated so that the scanning line coincides with the reference line XX. By detecting the rotation angle of the scanning surface of the light beam at that time, the inclination angle of the moving body V with respect to the reference line XX can be measured. In addition, in FIG. 3, since the light beam is rotated and scanned toward the front of the moving body V, the reference line
The left and right inclination of the moving body V with respect to -X can be measured. If the light beam is rotated and scanned toward the right side or the left side of the moving body V, the inclination of the moving body V in the front-back direction with respect to the reference line XX can be measured.

Hereinafter, one embodiment of the present invention will be described in detail with reference to FIGS. 6A to 11.

6A and 6B are external views showing the beam scanner BS provided in the moving body V, in particular, FIG. 6A shows its side view, and FIG. 6B shows its top view. In the figure, the beam scanner
The BS includes a cylinder 4 housing a laser light source and a light receiving element, and a rotary encoder EC1 and a motor M1 connected to the cylinder 4. Motor M1
By rotating the cylinder 4, the laser beam
Rotate and scan the LB. Rotary encoder EC1
is the rotation angle of motor M1 and therefore the laser beam
Detects the rotation angle of LB. Rotary encoder
EC1, cylinder 4, and motor M1 are held by holding member 5. A rotary encoder EC2 and a motor M are provided at the center of the side surface of this holding member 5.
2 are concatenated. The motor M2 rotates the holding member 5, thereby rotating the optical scanning surface formed by the laser beam LB. Rotary encoder
EC2 detects the rotation angle of the motor M2 and therefore the rotation angle of the optical scanning surface. A motor M3 and a rotary encoder EC3 are connected to the outer circumferential side of the motor M2. Motor M3 is motor M
By rotating 2, the optical scanning surface formed by the laser beam LB is rotated in the vertical direction in FIG. 6A. The rotary encoder EC3 detects the vertical rotation angle of the motor M3 and therefore the optical scanning surface. Motor M3 and rotary encoder EC3 are held by holding member 6. This holding member 6 is fixed to the moving body V.

FIG. 7 is a longitudinal sectional view of the cylinder 4 shown in FIG. 6A. In the figure, a laser light source 5 such as a semiconductor laser is provided on the inner peripheral wall of a cylinder 1.
Laser beam emitted from this laser light source 5
LB is emitted to the outside from a hole 6 formed in the side surface of the cylinder 4. In addition, inside the cylinder 4, a half mirror 7 is located approximately 45 mm on the optical path of the laser beam LB.
placed at an angle of degrees. This half mirror 7 is
The laser beam LB from the laser light source 5 is passed through, and the light reflected by the corner cube CC and returned is reflected in the direction of the bottom surface 41 of the cylinder 4. A light receiving element BD is provided on the bottom surface 41 of the cylinder 4 to receive the light reflected by the half mirror 7.
is placed. As shown in FIG. 8, this light receiving element BD consists of semicircular light receiving elements BD1 and BD2.
and a small circular light receiving element BD0 placed in the center.
Consisting of

FIG. 9 is a schematic block diagram of one embodiment of the present invention. In the figure, the CPU 10 includes ROM 11
and RAM 12 are connected. ROM11 is
For example, an operating program as shown in FIG. 10 is stored, and the CPU 10 operates according to this operating program. An interface 13 is further connected to the CPU 10. This interface 13 includes light receiving elements BD1, BD1 and BD.
The light receiving output from 2 is given. In addition, the outputs of these light receiving elements BD0, BD1 and BD2 are OR
It is applied to interface 13 via gate 14. Further, drive circuits 15, 16 and 17 are connected to the interface 13. Each of the drive circuits 15 to 17 drives the motors M1 to M3 based on control signals given from the CPU 10 via the interface 13. Furthermore, the interface 13 includes encoders EC1 to EC3.
The angular output from is given.

FIG. 10 is a flowchart for explaining the operation of the CPU 10 shown in FIG.

The operation of one embodiment of the present invention will be described below.

First, in step 1 shown in FIG. 10 (abbreviated as S in the figure), the drive circuit 15 is activated,
Rotational scanning of the laser beam LB by the motor M1 is started. Subsequently, in step 2, the pattern of the light receiving output of the light receiving element BD is read. That is, the output of the OR gate is sampled and stored in the RAM 12, and each time one scan of the laser beam LB by the motor M1 is completed, the CPU 10 reads the pattern of the light reception output stored at that time from the RAM 12. read Next, the process proceeds to step 3, where it is determined whether the scanning line on the corner cube CC passes through the optical axis center 00 of the corner cube CC. This determination is made based on whether or not the light receiving element BD0 has derived a light receiving output during one scan of the laser beam LB. That is,
Light incident near the optical axis center 00 (see Figure 5) of the corner cube CC returns to the beam scanner BS following exactly the same optical path as the incident light. The laser light thus returned is reflected by the half mirror 7 and hits the light receiving element BD located at the center of the light receiving element BD. Therefore, if the light receiving output is derived from the light receiving element BD0 during one scan of the laser beam LB, it means that the scanning line on the corner cube CC passes over the optical axis center 00.

In step 3 above, the corner cube
If it is determined that the scanning line on CC does not pass over the optical axis center 00, the process proceeds to step 4. In step 4, it is determined whether the scanning line is shifted above the reference line XX (in FIG. 5). If it is determined that the scanning line is deviated above the reference line XX, the process proceeds to step 5, in which the motor M3 is rotated clockwise (in the direction of arrow R) in FIG. 6A. As a result, the scanning line on the corner cube CC gradually lowers. On the other hand, if it is determined in step 4 that the scanning line is deviated below the reference line XX, the process proceeds to step 6. In this step 6, contrary to step 5,
Motor M3 is rotated counterclockwise (in the direction of arrow L) in FIG. 6A. This causes the scan line to gradually rise. After steps 5 and 6 described above, the operations from step 2 onwards are repeated again.

Here, whether the scanning line is shifted upward or not is determined by
The determination is made based on which of the light receiving elements BD1 and BD2 derives the light receiving output longer in one scan, and the reason for this will be explained below. 1st
As explained in the figure, the light incident on the corner cube CC does not exit from the same part, but from a point symmetrical position with respect to the optical axis O. Therefore, for example, in the corner cube CC in Fig. 5, the light incident on the light reflecting mirror surface above the reference line The light is also reflected by the lower light reflecting mirror surface and emitted. Conversely, the light that enters the light reflecting mirror surface below the reference line XX is reflected internally multiple times and is finally reflected by the light reflecting mirror surface above the reference line XX. and emit light. On the contrary,
The light receiving element BD1 is arranged to receive light emitted from the reflecting mirror surface below the reference line XX. Moreover, the light receiving element BD2 is arranged so as to receive the light emitted from the reflecting mirror surface above the reference line XX. Now, if we consider the case where the scanning line on the corner cube CC is shifted upward with respect to the optical axis center 00, in this case, the upper scanning line is larger than the lower scanning line with reference line XX as the boundary. become longer. Therefore, the reflected light emitted from the corner cube CC takes longer time to exit from the lower light reflecting mirror surface with respect to the reference line XX as a boundary than it takes to exit from the upper light reflecting mirror surface. Accordingly, in the light receiving element BD, the light receiving time of the light receiving element BD1 becomes longer than the light receiving time of the light receiving element BD2. Therefore, when the time for deriving the light receiving output from the light receiving element BD1 is longer than the deriving time for the light receiving output from the light receiving element BD2, it can be determined that the scanning line is shifted upward with respect to the optical axis center 00. Contrary to the above, the light receiving element BD
When the time for deriving the light receiving output from the light receiving element BD1 is longer than the time for deriving the light receiving output from the light receiving element BD1, it can be determined that the scanning line is shifted downward with respect to the optical axis center 00.

By repeating the operations in steps 2 to 6, when the scanning line comes to pass over the optical axis center 00 of the corner cube CC, this is determined in step 3, and the process proceeds to step 7. In step 7, the angle output of the rotary encoder EC3 is stored in the RAM 12. Note that the angle output of the rotary encoder EC3 at this time represents the elevation angle of the corner cube CC with respect to the moving body V. next,
Proceeding to step 8, the angular output of the encoder EC2 is stored, and the pattern of the light receiving output of the light receiving element BD is read again. Then, proceed to step 9, and check the pattern of the received light output that was read this time,
The pattern of the received light output that was read at the end of the previous scan and the one before the previous scan is compared. Specifically, the number of pulses included in the received light outputs is compared. if,
If the number of pulses is the same, it is determined that the pattern is the same, and if the number of pulses is different, it is determined that the pattern is different. As shown in FIG. 5, when the scanning line is upward to the right, the received light output includes one pulse, and conversely, when the scanning line is downward to the right, the received light output includes three pulses. Next, in step 10, based on the comparison result in step 9, the corner cube is
It is determined whether the scanning line on CC matches the reference line XX. If the pattern of the received light output that was read this time is different from the pattern of the received light output that was read last time, and the received light output that was read this time is the same as the pattern of the received light output that was read two times before, then the scanning line is the reference line. It is determined that it matches XX. That is, in this embodiment, it is considered that the scanning line coincides with the reference line XX when it alternately repeats an upward-sloping state and a downward-sloping state in the vicinity of the reference line XX.

If it is determined in the above-mentioned step 10 that the scanning line does not coincide with the reference line XX, the process proceeds to step 11. In step 11, it is determined whether or not the scanning line on the corner cube CC is upwardly to the right (in FIG. 5) with respect to the reference line XX. This judgment is made based on the pattern of the light reception output read in step 8 described above. That is, if the received light output includes one pulse, it is determined that the scanning line is upward-sloping to the right, and if the received light output includes three pulses, it is determined that the scanning line is downward-sloping to the right. If it is determined that the scanning line is upward to the right, the process proceeds to step 12, where the motor M2 is rotated in a direction in which the scanning line is downward to the right. On the other hand, if it is determined that the scanning line is downward to the right, the process proceeds to step 13, where the motor M2 is rotated in a direction in which the scanning line is upward to the right. After steps 12 and 13, the operations from step 8 onwards are repeated again. Step 8
When it is determined that the scanning line coincides with the reference line XX by repeating the operations of steps 1 to 13, step 14
Proceed to. In step 14, the average angle between the angle output of rotary encoder EC2 read this time and the angle output of rotary encoder BC2 read last time is calculated. Then, the average angle is the inclination angle of the moving body V with respect to the reference line XX.
It is stored in RAM12. Thereafter, the operation returns to step 2 again.

FIG. 11 is a diagram showing another example of the mask formed on the corner cube CC. In the figure, a plurality of rows of masks MA1 to MA4 are formed on the reflective mirror surface 3a of the corner cube CC. Note that the mask formed on the corner cube CC is not limited to those shown in FIGS. 5 and 11, and various other masks may be used. That is,
The mask may be formed so that the pattern of reflected light changes depending on whether the scanning line is upward to the right or downward to the right with respect to the reference line.

In the above embodiment, the inclination angle of the moving body V with respect to the reference line XX is measured, but of course the inclination angle of a fixed object can also be measured. Moreover, the moving object V is not limited to one that travels on the ground, but may be one that flies in the air like an airplane.

Effects of the Invention As described above, according to the present invention, the inclination angle of an object is measured using the special optical property of the light reflecting means that reflects light in the same direction as the incident light. , the inclination angle can be measured very accurately, and the device is simple and inexpensive.

[Brief explanation of the drawing]

FIG. 1 is an external perspective view of the corner cube.
FIG. 2 is a three-dimensional perspective view of a mirror housed inside the corner cube. FIG. 3 is a diagram showing a state in which the inclination angle of a moving body V is measured using an embodiment of the present invention. FIG. 4 is a view of the beam scanner BS from above the moving body V, and shows the scanning state of the light beam. Figure 5 shows Corner Cube CC
FIG. 3 is a diagram showing the relationship between the mask MA formed in the mask MA and its reflected light. 6A and 6B are external views showing a beam scanner BS used in one embodiment of the present invention, in particular, FIG. 6A shows its side view, and FIG. 6B shows its top view. FIG. 7 is a longitudinal sectional view of the cylinder 4 shown in FIG. 6A. FIG. 8 is a plan view of the light receiving element BD shown in FIG. 7. FIG. 9 is a schematic block diagram of one embodiment of the present invention. FIG. 10 is a flowchart showing the operation of the CPU 10 shown in FIG. 9. FIG. 11 is a diagram showing another example of the mask formed on the corner cube CC. In the figure, CC is a corner cube, V is a moving object, BS is a beam scanner, 1a to 3a are light reflecting mirror surfaces, MA is a mask, and MA' and MA'' are masks.
Shadow created by MA, M1 to M3 are motors,
EC1 to EC3 are encoders, 5 is a laser light source,
BD is a light receiving element, 10 is a CPU, 11 is a ROM, 1
2 indicates RAM.

Claims (1)

[Claims] 1. A system for measuring the angle formed by an object with respect to a predetermined reference line, comprising a plurality of light reflecting mirror surfaces combined three-dimensionally, and directing incident light in the same direction. a light reflecting means for reflecting; a mask formed on a predetermined area of the light reflecting mirror surface; a rotating scanning means provided on the object and rotating and scanning a sharply directional light beam toward the light reflecting means; a light receiving means provided in association with the rotary scanning means for receiving the reflected light from the light reflecting means; a light receiving means provided in relation to the rotary scanning means and configured to detect a light scanning surface formed by the light beam; a displacement means for displacing the optical scanning surface so that it coincides with the reference line;
An inclination angle measuring system, comprising: a driving means for driving the displacement means based on an output of the light receiving means; and a means for detecting the angle by detecting the amount of displacement of the optical scanning surface by the displacement means. 2. The displacement means includes: a first displacement means that displaces the optical scanning surface in a direction perpendicular to the optical scanning surface; and a second displacement means that rotates the optical scanning surface, and the driving means includes: After driving the first displacement means so that the optical scanning surface hits the center of the optical axis of the light reflecting means, driving the second displacement means to rotate the optical scanning surface so that it aligns with the reference line. 2. The inclination angle measurement system according to claim 1, wherein the angle detection means includes means for detecting the rotation angle of the optical scanning surface by the second displacement means.