JP2000097697A - Unmanned truck position detection system - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a system which eliminates the need for a guide line which were needed for a guide leading system and is able to detect the position of an unmanned truck without processing travel environment. SOLUTION: By a method used for this system, A rotary scan with the laser light from a scanning type laser radar 10 mounted on the unmanned truck is made in a horizontal plane to find the distances and directions to feature points present in the travel environment from the times needed for the reflected light from the feature points to return and the irradiation directions of the laser light. In this case, such feature points that the variation rate of the distance to the angle is larger than a certain value, the interval between adjacent feature points is larger than a specified distance, and the angle containing the two feature points is larger than a specific value are detected.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to an automatic guided vehicle position detection system. More specifically, the present invention relates to a method for detecting the position of an automatic guided vehicle using a laser radar.

[0002]

2. Description of the Related Art Various guide guidance methods have been proposed as position detection methods for an automatic guided vehicle. For example, a cable is buried in the floor of the traveling route, and electromagnetic waves generated by applying a high-frequency current to the cable are detected by two pickup coils attached to the vehicle body, a course deviation is detected, and an automatic guided vehicle is connected to this cable. There is an electromagnetic induction method for guiding along.

[0003] There are also an optical guidance system and a magnetic guidance system in which an optical reflection tape or a magnetic tape is attached to the floor of a traveling route and an automatic guided vehicle is guided along the optical reflection tape or the magnetic tape.

[0004]

However, the above-described conventional guide guiding method has the following disadvantages. (1) It is difficult to change the travel route layout. Unmanned guided vehicles can only travel along guide lines such as electric wires, optical reflection tapes, and magnetic tapes. I have to fix it.

[0005] (2) Construction cost increases when the length of the guide line is long. Since the installation cost of the guide line is proportional to the traveling distance, the cost increases as the length of the guide line increases. (3) Restriction on floor condition In the conventional method, it is necessary to embed an electric wire on the floor surface or to attach a tape, so there is a restriction on floor condition. For example, in the case of the electromagnetic induction method, since the electric wire is embedded in the floor surface, a cutting operation on the floor surface is required. Therefore, such an operation cannot be performed in a place where the floor is thin.

In the case of the optical guidance system, it is difficult to use it on a glossy floor surface, and if the reflection tape is dirty, it affects the guidance of the automatic guided vehicle. In the case of the magnetic induction system, if a magnetic material is present on the floor surface, this may affect the guidance of the automatic guided vehicle, and may run off the course. In addition, these methods cannot be used on unpaved paths, or paths that have a mesh cut into the floor, such as clean rooms.

The present invention provides a system using a laser radar as a guideless guidance system for an automatic guided vehicle that does not require such a guide. That is, the present invention
It proposes an automatic guided vehicle position detection method that eliminates the need for laying work for guides, which was a problem in the conventional method, makes it easy to change the course layout, and can reduce laying work costs. It is not affected by surface conditions.

[0008]

An automatic guided vehicle position detecting method according to the present invention which solves the above-mentioned problems is to rotate and scan a laser beam in a horizontal plane from a scanning laser radar mounted on the automatic guided vehicle, and to detect the position in a traveling environment. In the method for determining the distance and direction to the reflecting plate from the time until the reflected light returns from the characteristic point and the irradiation direction of the laser light, the characteristic point is such that the rate of change of the distance to the angle is equal to or greater than a certain value. The method is characterized in that the distance between two adjacent feature points is greater than or equal to a specified distance, and the angle at which the two feature points are anticipated is greater than or equal to a specified value. .

[0009]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention proposes a system using a laser radar as a guideless guidance system for an automatic guided vehicle. Generally, a laser radar is a device that irradiates a measurement target with laser light, detects reflected light thereof, and measures a distance to the measurement target from a time difference from irradiation to detection of reflected light.

As shown in FIG. 1, the laser radar used in the present invention is a scanning laser radar 10 which rotates and scans a laser beam in a horizontal plane. That is, the turntable 2 is rotatably mounted on the turntable 1, and a mirror 3 inclined at 45 degrees to the horizontal plane is installed on the turntable 2. An inclined half mirror 4 is provided, and a photodiode 5 and a laser 6 are installed immediately above the half mirror 4 and laterally in the horizontal direction.

Therefore, while rotating the turntable 2 and the mirror 3 on the turntable 1 as shown by arrows, the laser emitted horizontally from the laser 6 is bent vertically downward by the half mirror 3 and further turned by the mirror 3. It is bent in the horizontal direction and projected on the reflection plate 7. On the contrary, the light reflected from the reflection plate 7 is bent vertically upward by the mirror 3, passes through the half mirror 4, and is detected by the photodiode 5.

The turntable 1 is provided with an encoder for detecting a rotation angle of the turntable 2, a tachometer, and the like. Here, since the laser radar 10 can detect a distance to a place where an object that blocks light is present, the present invention detects a feature in the traveling environment of the automatic guided vehicle without using a reflection plate, and detects a position and a position. The direction is detected. Such a laser radar 10 is mounted on an automatic guided vehicle, and the distance and direction from the laser radar 10 to a plurality of characteristic points existing in the vehicle traveling environment are detected.

Therefore, according to the present invention, there is no need to lay the guide, which has been a problem in the conventional method, the course layout can be easily changed, and the laying work cost can be reduced. Which is not affected by floor conditions.

[0014]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, the present invention will be described in detail with reference to embodiments shown in the drawings. One embodiment of the present invention is shown in FIGS. As shown in FIG. 2, the laser radar 10 is mounted on the automatic guided vehicle 20, and the laser beam is rotationally scanned (scanned) in a horizontal plane by the laser radar 10, and a corner formed by columns, walls, and the like existing in the traveling environment is determined. The position and direction are detected from the extracted and detected position data of the corner (inputted in advance). For example, in the case of FIG. 2, the characteristic points (corners of walls, columns, etc.) are (X ₁ ,
Y ₁ ), (X ₃ , Y ₃ ), and (X ₄ , Y ₄ ).

Therefore, in this embodiment, instead of the reflecting plate,
In addition, three feature points (X₁, Y₁), (X _Three, Y_Three),
(X_Four, Y_Four) Is used to calculate the position of the automatic guided vehicle. one
The data obtained in each scan is
It is a combination of distance females in this
The corner is detected as in (3). (1) Extraction of feature points

A feature point is that the following conditions are added from data obtained by one scan. Data is obtained at certain angles. P _i = | L _i + L _{i + 2} −2L _{i + 1} |> P _th i = 0,... M−2 where P _i is equivalent to | d ² L _i / dθ _i ² | . P _th
Is a set value.

(2) Straight line detection Two adjacent feature points of the detected feature points are defined as a start point and an end point, and the interval between them is equal to or more than a specified value, and at all points between them, the start point and the end point from that point. When the difference between the anticipated angle and 180 degrees is equal to or smaller than a specified value, the line is detected as a straight line having two feature points as a start point and an end point. (3) Angle detection When a feature point is the start point or end point of two adjacent straight lines,
This point is detected as a corner.

There are various methods for calculating the position of the automatic guided vehicle using the detected corner as a feature point. For example, when the position of the automatic guided vehicle 20 is known in advance, two closest feature points from the automatic guided vehicle are selected, and the position of the automatic guided vehicle is solved from the selected two feature points into a two-dimensional simultaneous equation. Can be obtained by

When the position data of the feature point is known in advance, the detection error can be reduced by associating the position data of the feature point with the detected feature point. Furthermore, it is also possible to determine the position of the automatic guided vehicle from each of three or more characteristic points, and select a point at which the maximum value of the average value is the smallest.

Note that the position of the automatic guided vehicle can be calculated by using the end points (start point, end point) of the straight line detected in the above embodiment instead of the corners. Further, it is also possible to calculate the position of the automatic guided vehicle using all the detected corners, end points, and reflectors.

[0021]

As described above in detail with reference to the embodiments, according to the present invention, the guide wire required in the guide guidance system is not required, and the unmanned transport without modifying the traveling environment. Car position can be detected. In particular, since there is no need to install a reflection plate, there is an advantage that construction can be performed more easily.
Further, by using the end points instead of the corners as the feature points, the position can be easily detected, and furthermore, when used in combination with the reflector, accurate position detection is also possible.

[Brief description of the drawings]

FIG. 1 is a structural diagram of a laser radar.

FIG. 2 is a bird's-eye view showing a traveling environment of the automatic guided vehicle according to one embodiment of the present invention.

FIG. 3 is a plan view of FIG. 2;

[Explanation of symbols]

 Reference Signs List 1 turntable 2 turntable 3 mirror 4 half mirror 5 photodiode 6 laser

 ──────────────────────────────────────────────────続 き Continued on the front page F term (reference) 5H301 AA01 AA10 CC03 CC06 FF10 GG08 5J084 AA02 AA05 AA10 AB16 AC02 BA03 BA11 BA36 BB24 CA03 EA04 EA27

Claims (1)

[Claims] 1. A scanning laser radar mounted on an automatic guided vehicle scans a laser beam in a horizontal plane in a rotating plane, and returns a reflected light from a characteristic point existing in a traveling environment to a return direction and a laser beam irradiation direction. In the method for calculating the distance and the direction from the feature point to the feature point, the change rate of the feature point with respect to the angle is equal to or greater than a predetermined value, and the interval between two adjacent feature points is equal to or greater than the specified distance. Yes, and 2
An automatic guided vehicle position detection method that detects an object having an angle that is greater than a specified value in anticipation of two feature points.