JPH0259931B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a method of measuring the position of a moving object such as an unmanned vehicle or an aircraft using a light beam in order to guide it. In Patent Application No. 57-90836 and Japanese Patent Application No. 58-1509, etc., a light beam emitted from a moving body is rotated and scanned, and light beams emitted from a corner cube prism provided at at least three fixed positions apart from the moving body are scanned. The present invention relates to a method of detecting the reflected light beam of the emitted light beam to detect the azimuth angle of each corner cube prism with respect to the moving body, thereby measuring the position of the moving body based on the principle of triangulation.

This method of measuring the position of a moving object using a light beam is more effective than the previously thought methods of using a television camera or ultrasonic waves.
It has the basic advantage of being significantly superior in terms of system scale, complexity, measurement accuracy, noise, etc.

However, in such a conventional position measuring method using a light beam, only three corner cube prisms are arranged around the outer periphery of a given measurement range, which is the movement range of a moving body assumed in advance, and these three corner cube prisms are The position of the moving object was calculated and measured from the positional relationship of the Cube prisms (known fixed distances between them) and the three azimuth angle detection results, but in this case, the Although a fairly high degree of measurement accuracy can be obtained in one part, the measurement accuracy tends to decrease in other parts, making it impossible to ensure a sufficiently high measurement accuracy over the entire measurement range.

This will be explained in more detail using FIG. 1 as follows. In this figure, corner cube prisms 1', 2', and
3' is installed, where each side is 100m,
Contour distribution diagram of the maximum error in position measurement, assuming that the azimuth angle measurement error by each corner cube prism 1', 2', and 3' is ±0.01° (each value is in cm)
It was created through calculation simulation. As you can see, within the range of contour lines shown by solid line a to dotted line b, that is, in the central part of triangle c connecting each corner cube prism 1', 2', and 3', the position is very accurate. Although measurement is possible, the measurement accuracy is considerably degraded in other parts, ie, near each corner cube prism 1', 2', 3', and in the outer part of the triangle c.

The present invention has been made in view of the above-mentioned circumstances, and is aimed at a mobile object whose position can be measured with sufficiently high accuracy over the entire measurement range, regardless of the shape of the given measurement range. The object of the present invention is to provide a position measurement method.

To achieve the above object, the method for measuring the position of a moving body according to the present invention includes: (a) fixed positions spaced apart from the outer periphery of a given measurement range of the corner cube prism by a predetermined distance, respectively; (a) First, any three of the detection results of the azimuth of the four corner cube prisms with respect to the moving body are Determine which corner cube prism among the four corner cube prisms the position of the moving body calculated using the azimuth angle is closest to, and (c) Next, apply the determination result to Based on this, the position of the moving body is calculated again using three azimuths corresponding to the three corner cube prisms: the corner cube prism closest to the moving body and the two corner cube prisms on both sides thereof. This method is characterized by the following steps:

The effects of the above features are as follows.

That is, before calculating the final position measurement result, the position of the moving object is first calculated in advance, and based on the primary calculation result, three corner cube prisms that can be expected to have the highest measurement accuracy are selected. Finally, the position of the moving object is recalculated using the azimuth detection results of the three selected corner cube prisms, and each corner cube prism is within the moving area of the moving object. However, since it is installed at a certain distance from the outer periphery of a given measurement range, it is difficult to determine which part of the measurement range A the moving object V is located at, as illustrated in Figure 2 A, B, C, and D. Regardless of the location, the moving object V
The final position of the moving body V is measured based on the azimuth angles corresponding to the three corner cube prisms (indicated by black circles) located at the vertices of the triangle that surrounds the central part of the moving body V. That will happen. Therefore, regardless of the position of the moving object V, that is, even if the moving object V is located near a corner within the measurement range A, or wherever within the measurement range A, the This made it possible to measure its position with high measurement accuracy.

Embodiments of the method of the present invention will be described below based on the drawings.

FIG. 3 is a plan view showing the principle of a method for detecting the position of a moving object V, such as an automatic lawn mower, for example.

In the figure, A indicates a given measurement range which is the expected movement area of the mobile body V, and known fixed positions x ₁ , y are located outside this measurement range A and are spaced a predetermined distance from the outer periphery of the measurement range A, respectively. ₁ , x ₂ , y ₂ , x ₃ , y ₃ , x ₄ , y ₄ and forming a substantially square shape as a whole, a total of four corner cube prisms 1, 2, 3, 4 are arranged. The predetermined distance is 10% to 50% of the diagonal length of measurement range A.
A suitable amount is preferably about 20%. These corner cube prisms 1, 2, 3, 4 are
Each of these is commercially available and has the optical property that a light beam incident from any direction is reflected back along the path of incidence.

On the other hand, a rotationally scanned light beam is emitted from the moving body V, and by receiving reflected light beams of the emitted light beam from each of the corner cube prisms 1, 2, 3, and 4, Mobile object V
Each corner cube prism 1, 2,
3 and 4 azimuths are detected.

Now, as a means for emitting a rotationally scanning light beam, a prism 7 rotated by a laser beam generator 5 and an electric motor 6 is loaded on the moving body V as shown in FIG. Possibly by rotating the laser beam. This prism 7 is used to reduce the weight of the rotating mass in order to increase responsiveness when controlling the rotational speed.
A plane mirror may be used instead of the prism 7.

8 is a half mirror, and 9 is a light receiver for detecting the reflected light from the corner cube prisms 1, 2, 3, and 4.

An absolute encoder 10 is directly connected to the motor 6 and outputs the direction of the prism 7, and this output is input to a rotational speed controller computer 11.

Then, the output of the encoder 10 when the light receiver 9 detects the reflected light from each of the corner cube prisms 1, 2, 3, and 4 (each of the corner cube prisms 1, 2, 3, and 4 for the moving body V) azimuth) is input into the position calculation calculator 12, and from these azimuths, the four horizontal angles θ ₁ , θ ₂ , θ ₃ , θ ₄ formed by the corner cube prisms are calculated. Among the four horizontal angles θ ₁ , θ ₂ , θ ₃ , θ ₄ , two horizontal angles (θ ₁ and θ ₂ in this example) calculated from the three azimuth angles and each corner cube prism 1, 2 , 3, 4 known distance l ₁ ,
Two of l ₂ , l ₃ , and l ₄ (l ₁ and l ₂ in this example)
By using the principle of triangulation, more specifically, the circumferential angle theorem, the line segment between the three corner cube prisms 1, 2, and 3 is uniquely determined as a chord, 2 circles C ₁ , C By finding the intersection of ₂ , the moving body V
The positions xv and yv of are calculated first. Note that this calculation principle has been explained in detail in the earlier application mentioned above, so only a general explanation will be given here.

Next, from the primary calculation results xy, yv of the position of the moving body V obtained as described above, the position xv, yv and each corner cube prism 1,
2, 3, 4 positions x ₁ , y ₁ , x ₂ , y ₂ , x ₃ , y ₃ , x ₄ ,
Calculate the distances L ₁ , L ₂ , L ₃ , L ₄ between y ₄ and which corner cube prisms 1, 2,
3 and 4, and based on the determination result, the corresponding corner cube prism 4 and the corner cube prisms 1 and 3 on both sides thereof.
Select one. And the selected 3
Two horizontal angles θ ₃ , θ _{4 and two distances l 3 , l 4} corresponding to the corner cube prisms 1, ₃ , ₄
The positions xv and yv of the moving object V are recalculated using the same principle as in the above-mentioned primary calculation, and the position is finally determined with high accuracy.

In this embodiment, the four corner cube prisms 1, 2, 3, and 4 are arranged so as to form a substantially square shape as a whole, but the present invention is not limited to this, and restrictions due to topography, etc. For this reason, there is no problem in arranging them in the form of a rectangle, a parallelogram, or a general quadrilateral, for example. However, it is certain that the closer the shape is to a square, the better the position measurement accuracy can be obtained.

Furthermore, prior to the regular position calculation, the primary calculation method for determining which corner cube prism the moving object is closest to is not to actually calculate the position as explained in the above embodiment. The determination may be made directly from the azimuth angle of each corner cube prism with respect to the moving body.

[Brief explanation of the drawing]

Fig. 1 is an explanatory diagram of problems in the conventional method, Fig. 2 A, B, C, and D are plan views for explaining the effects of the present invention, and Figs. FIG. 1 is a plan view and a configuration diagram of a moving body showing an example. A...Measurement range, V...Moving object, 1, 2, 3,
4... Corner cube prism.

Claims (1)

[Claims] 1. Rotating and scanning the light beam emitted from the moving body V, and reflecting the emitted light beam from corner cube prisms provided at at least three fixed positions apart from the moving body V. A method of detecting the azimuth angle of each corner cube prism with respect to the moving object V by detecting a light beam, and thereby measuring the position of the moving object by the principle of triangulation, the method comprising: are arranged at fixed positions each a predetermined distance outward from the outer periphery of a given measurement range A, which is the movement area of the moving body V, and in a state where the whole forms a rectangle. The position of the moving body V calculated using any three azimuths of the detection results of the azimuths of the four corner cube prisms 1, 2, 3, and 4 with respect to the moving body V is 4
It is determined which of the corner cube prisms 1, 2, 3, and 4 the corner cube prism is closest to, and then, based on the determination result, the corner cube prism closest to the moving object V is determined. The position of the moving body is characterized in that the position of the moving body V is recalculated using three azimuths corresponding to three corner cube prisms: a prism and two corner cube prisms on both sides thereof. Measuring method. 2 the four corner cube prisms 1;
2. A method according to claim 1, characterized in that 2, 3, and 4 are arranged so as to form a square or approximately a square as a whole.