JPS5975175A - How to measure the current position of a moving object - Google Patents

Abstract

PURPOSE:To find the current position of a moving body accurately by photodetecting a laser beam emitted from three fixed stations to finding the photodetecting bearing of each beam, and calculating specifically on the basis of the photodetection bearing of the position of each fixed station. CONSTITUTION:Three fixed stations A-C are arranged in the movement area of an automobile 1 and a laser beam sending means in scanned within a specified range to send the laser beam from the respective stations. The automobile 1 is provided with an omnibearing photodetector 2 which photodetects the beams sent from the stations A-C, and this photodetector finds the photodetection bearing of the laser beams from the stations. The photodetection bearing of each fixed station is inputted to a microcomputer 6, which calculates the current position of the automobile from the correlation with the position coordinates of the respective fixed stations.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of the Invention The present invention relates to a method for measuring the current position of a moving object, such as a car, an aircraft, a ship, etc., which automatically measures the current position of the object as it moves. .

(b) Prior art and its drawbacks Accurately grasping the current position of moving objects such as aircraft on an apron, transport vehicles in a factory, and tractors in a farm field requires automatic guidance of those moving objects. This is important for high precision.

Conventionally, as a method for easily measuring the current position of a moving object, methods using radio waves such as LORAN, Decca, and OMEOA have been put into practical use. However, all of these have the disadvantage that the measuring devices are large and the configurations are complicated.

(C) Object of the Invention An object of the present invention is to provide a method for measuring the current position of a moving object, which can measure the current position of a moving object with high precision with a simple configuration.

(d) Structure of the invention This invention can be summarized as follows.

The laser beam sending means provided at each of the three fixed stations scans a specific range, and the light receiving surface of one light receiving means on the moving object is scanned in all directions. The light receiving direction with respect to the laser beam from each fixed station is determined from the change in the light receiving level based on the difference between the direction of the laser beam from each fixed station received by the light receiving means on the moving object side and the light receiving angle of the light receiving means at that time. demand. Then, the measuring method of the present invention calculates the current position of the moving object based on the light receiving direction determined as described below and the position coordinates of each fixed station, and according to a predetermined calculation formula. It is characterized by what it did.

(e) Description of Embodiments FIG. 1 is a diagram showing the principle of measuring the current position of a vehicle in an automatic vehicle guidance system that implements the measuring method of the present invention. A car 1 as a moving object moves within a moving area, and three fixed stations A, B, and C are provided within the moving area. A laser lighthouse is fixed to each fixed station. Each laser lighthouse is a device that sequentially scans a laser beam in all directions in a given azimuth direction, and corresponds to the laser beam sending means of the present invention. When each fixed station is arranged at the periphery of the moving area, the scanning range of each laser lighthouse does not have to be omnidirectional.

The automobile 1 is provided with a control section shown in FIG. One light receiver 2 is arranged at a predetermined location on the main body of the automobile 1. The light receiver 2 consists of a cylindrical rotating body rotated by a drive motor 7, and has a light receiving element 3 such as a PIN photodiode inside. The light receiving element 3 is attached so that its light receiving surface is exposed on the side surface of the rotating body. The rotation shaft of the drive motor 7 is connected to the rotation shaft of the encoder 5 by a connecting portion 4 . The encoder 5 has a rotating shaft that rotates in conjunction with the light receiver 2, and outputs a pulse signal every minute rotation thereof.

The encoder 5 may be, for example, an electromagnetic pulse encoder consisting of a gear directly connected to a rotating shaft and a fixed magnet pickup, or a rotating disk with a slit formed along its circumference connected to the rotating shaft, and light passing through the slit. An optical pulse encoder that detects with a phototransistor or the like is used. Further, the rotation start position of the light receiver 2 is such that the normal direction of the light receiving surface of the light receiving element 3 is the traveling direction of the vehicle body (indicated by OD in FIG. 1).
is determined in the direction that corresponds to With the direction of this rotation start position as a reference direction, the encoder 5 outputs several pulse signals for each rotation. The light receiver 2 is rotated by a drive motor 7 at a constant rotation speed, and the light receiving surface of the light receiving element 3 is scanned in all directions.

FIG. 3 shows the light receiving output of the light receiving element 3 during one rotation. The horizontal axis direction in the figure represents the rotation angle, and each output corresponds to the received light level value when the encoder 5 outputs the cipher signal. As can be seen from the figure, since laser beams from three fixed stations are received, three peaks appear in the received light output. As shown in FIG. 4 (5), when the incident direction of the laser beam and the normal direction of the light receiving surface coincide, the amount of light received at that time is maximum. On the other hand, as shown in FIG. 4(B), when the angle θ between the incident direction of the laser beam and the light-receiving surface is not a right angle, the amount of received light decreases as the angle θ becomes larger or smaller. . in this way,
A difference occurs between the incident direction of the laser beam and the light receiving angle of the light receiving element 3, and this difference increases when a light receiving element with blunt directivity is used. Therefore, the output of the light-receiving element 3 is guided to the comparator circuit 8, and only the output above a certain level shown by the dashed line E in FIG. 3 is taken out. Comparison circuit 8
The output of the encoder 5 and the output of the encoder 5 are guided to the microcomputer 6. Then, the average value of the light receiving angles when the light receiving outputs above a certain level are measured is taken as the light receiving direction, and is determined by the arithmetic processing of the microcomputer 6, which will be described later.

Note that the rotation speed of the light receiver 2 that scans the light receiving surface is set to be sufficiently larger than the laser beam scanning speed of each laser lighthouse. Therefore, changes in the light receiving direction due to the movement of the automobile 1 can be measured with high accuracy following the movement. Alternatively, the rotation may be controlled by directly attaching a light receiver to the stepping motor without using the connecting portion 4.

``An automobile having a control section configured as described in Section 2,
As mentioned above, it is assumed that the object exists at a point O within the movement area facing in the direction of the arrow OD in FIG.

Each fixed station A is detected by scanning the light receiving surface of the light receiver 2 at point 0.
, B, and C.

This light receiver 2 provides a light receiving output having three peaks as shown in FIG. 3 above. The microcomputer 6 calculates the average value of the rotation angle corresponding to the pulse signal from the encoder 5 when the received light output is measured at a certain level or higher.
It can be found by the calculation process. The value obtained in this way is 3
Light-receiving azimuth angles θA, θB, θC when the light-receiving element 3 receives the laser beams sent out from each fixed station
becomes.

These light receiving azimuth angles are determined with the direction of OD as the reference zero degree, as described above. Based on this light receiving azimuth angle and the position coordinates of each fixed station, the following microcomputer 6
The current position of the vehicle 1 is determined by the calculation process.

The contents of the above calculation processing will be explained below.

Since the position coordinates of the three fixed stations A, B, and C are set in advance, the distance between these fixed stations is known. Therefore, let the distances between 48, 10, and OA be c, a, and b, respectively. Further, as shown in the formula below, the difference between the light receiving azimuth angles θC and θB is set as α, and the difference between OA and θC is set as β.

Sarani, between OA, between 01, between 00 (7) each 1ii111
11ff ['3゜J')+, F2.10 B 'C
Let be θ1. fs, h, f'3. θ1 is an unknown quantity and % Fl, F2. , f'3 and II, the current position of the vehicle 1 can be determined.

Therefore, by using the law of sine for △OBC and △OCA, the following formula can be obtained.

5111ps1n (2π-(/C+a+β+01))
A3 3. (/C, -7-1,, θ1-, yr) °
“°(3) From the above f21, (3), we have, so by expanding and rearranging this equation, we obtain the following equation.

Therefore, the angle θ1 is determined by the following formula.

... (5) Also, if θ is found, according to the following formula from equations (2) and (3), /'□1. A2. f3 is determined respectively.

sinα sinα Thus, according to the above formulas +51 and +61, θ
1. J'1,! ? 2. f'3 is calculated. Then, the current position of the automobile 1 can be known from this calculation result.

In this embodiment, the control section of the moving object includes a microcomputer, but an information processing section may be provided at a location separate from the moving object, and the output of light received by the light receiver may be transmitted to the information processing section.

(fl Effects of the Invention According to the present invention, the configuration is such that the laser beam sending means is placed at each fixed station and the light receiving means is provided on the moving object, and the measuring device can be made compact and simple. In addition, the light receiving direction data obtained by scanning the light receiving surface of the light receiving means in all directions and determining the change in the light receiving level based on the difference between the direction of the laser beam and the light receiving angle of the light receiving means is highly accurate data. , which has the advantage of increasing the accuracy of current position measurement.

[Brief explanation of the drawing]

FIG. 1 is a diagram showing the principle of measuring the current position of a car in a car automatic guidance system that implements the measuring method of the present invention.
Figure 2 is a block diagram showing the control unit installed in the same vehicle, Figure 3 is a diagram showing the light receiving output of the light receiver of the control unit, and Figure 4 is a diagram showing the light receiving output of the light receiver of the control unit.
The figure shows the relationship between the light receiving surface of the light receiver and the direction of incidence of the laser beam. ■... Car (moving object), 2... Light receiver, 3... Light receiving element, 4...
...Connection part, 5...Encoder, 6...
- Microcomputer, 7... Drive motor. Applicant Kubota Iron Works Co., Ltd. Agent Patent Attorney Hisao Komori

Claims (3)

[Claims] (1) A method for measuring the current position of a moving object, comprising:
The laser beam sending means provided at each fixed station scans a specific range, and the light receiving surface of one light receiving means at the moving object is scanned in all directions, and the laser beam from each fixed station is received by the moving object. The light receiving direction for the laser beam from each fixed station is determined from the change in the light receiving level based on the difference between the direction of the light receiving means and the light receiving angle of the light receiving means. A method for measuring the current position of a moving object, wherein the current position of the moving object is determined according to the formula. (2) The speed at which the light receiving surface of the light receiving means is scanned is greater than the laser beam scanning speed of the laser beam sending means;
A method for measuring the current position of a moving object according to claim 1. (3) The method for measuring the current position of a moving object according to claim 1, wherein the scanning range of the laser beam sent out from each fixed station is omnidirectional.