JPS62123506A - Position marker and method of detecting same - Google Patents

Abstract

PURPOSE:To detect the guide signal of a vehicle body as well as the position marker at a branching point with use of a guide sensor, by detecting the position marker at the part where the form or the material of a belt-shaped guide is changed from the change of the outputs of two detecting parts or the change of the sum signal. CONSTITUTION:A comparison level is set at the value higher than the maximum levels of output changes (a) and (b) of the rectilinear parts of the guides of rectifiers 7a and 7b and lower than the center intersecting point between the output changes (d) and (e) of the cross parts. A cross part is decided when both detecting parts exceed said comparison level. Therefore a desired position is accurately detected as long as the comparison level is set at the prescribed value and the meandering movement is limited within a fixed level. While a sum signal is obtained by supplying the rectified outputs of both rectifiers 7a and 7b to an adder 8. This sum signal is compared with a reference voltage level decided previously through a level comparator 9. This reference voltage level is decided for output the ON or OFF signal. This detecting method is available enough even in case the position is largely distant right or left away from the right-left meandering value of the rectilinear part.

Description

DETAILED DESCRIPTION OF THE INVENTION (Field of Industrial Application) The present invention relates to a position marker for guiding an unmanned vehicle and a method for detecting the position marker.

(Prior art) Various guides for guiding unmanned vehicles along predetermined travel routes have been reported, and it is well known that, for example, electric wires, aluminum foil, magnetic materials, etc. are used (automatic transportation technology). The guidance sensor installed in the unmanned vehicle (hereinafter referred to as the guide sensor) has two detectors inside at -m, and the difference signal between the outputs of both detectors is detected as shown in Figure 4. The direction and magnitude of the positional deviation of the vehicle body from the guide are outputted using the method (Japanese Patent Application No. 6O-011251). However, at the point where the guides intersect (hereinafter referred to as a branch point), an output corresponding to the vehicle body position deviation cannot be obtained. For this reason, the sixth problem that requires control that temporarily ignores sensor output at branch points is where on the course the branch point is. Conventionally, the location of a junction was communicated to an unmanned vehicle as follows. In other words, a separate indicator other than guidance called a branch marker is installed near the branch point, and the vehicle body is equipped with a marker sensor in addition to the guide sensor, which is used to detect the location of the branch point. Was. The same can be said of the stop marker at the stop point. A stop marker similar to a branch marker is installed at a predetermined stop position, and the same marker sensor is used to determine the stop position.

(Problem to be solved by the invention) By the way, when an unmanned vehicle passes through a junction, in order to know the location of the junction, it requires signs other than guidance, such as junction markers, and a dedicated sensor, as in the past. In this case, four branch markers are required for each branch point, for example, at a crossroads.

Furthermore, if deceleration markers for deceleration are required around the branch point, twice the number of markers will be required. Therefore, if the course has many branches, the number of markers will increase dramatically. For this reason, the disadvantage is that the more branches a course has, the more expensive it is to install markers, which accounts for the cost of laying the course. Also, since it requires a dedicated sensor, it has the disadvantage of being connected to a cost store knob.

If the branching part or stop position of the guide can be detected directly by the guide sensor, various markers and marker sensors can be removed, and therefore the installation cost of the course and the price of the vehicle body can be significantly reduced.

SUMMARY OF THE INVENTION An object of the present invention is to provide a position marker and a method for detecting the position marker, such as a branch point, in addition to a vehicle guidance signal using a guide sensor.

(Means for Solving the Problems) The present invention includes a guide sensor mounted on a vehicle body, which includes at least two detection parts for detecting a guide provided in a strip shape on the road surface, and the shape or material of the strip guide is changed. A position marker is detected by detecting a change in the output of both detection sections or a change in the sum signal of both detection sections, and as a position marker,
A position marker and a position marker detection method, characterized in that the shape of the guide is wide or narrow in the width direction, and the thickness or material of the guide is different from other guides.

(Function) The guide sensor of an unmanned vehicle usually has two detectors 1 on the left and right inside.
It has a, lb. These, both detection parts la, lb
has output characteristics shown by curves a and b in FIG. 2(a) for the linearly extending band-shaped guide 2 shown in FIG. 2(b). However, for example, as shown in Figure 2(c),
In the portion where the band-shaped guide 2 spreads left and right (this is called a cross section), the detection output increases due to the influence of the guide that spreads left and right, as shown by curves d and e in FIG. 2(a). The present invention detects a cross by utilizing the fact that the outputs of detectors la and lb both increase. There is no problem in practical use as long as the width of the cross section in the left and right directions is at least a certain size, taking into account the size of the sensor, the width of the guide, etc. Furthermore, if the guide sensor is sensing the material of the guide itself, by appropriately changing the thickness or material of a portion of the position marker, it can be used as a position marker that has the same effect on the sensor. Therefore, if such a cross is installed not only at the branch but also at the stop position, it can be used as a stop position marker.9 Next, as another method, we will focus on the sum signal of the outputs of both detection units. In the same figure, the sum of curves a and b is C1 in the same figure, and d
, e is f. The cross can be detected by utilizing the fact that the sum signal increases significantly at the cross.

(Example) Below, a case will be shown in which an example of the present invention is applied to a magnetic induction system using ferrite, which is a magnetic material, as a guide. FIGS. 1(a) and 1(b) show configuration diagrams of a position marker detection section of a guide sensor as an embodiment of the present invention. exciter 3
An excitation current from an oscillator 4 is passed through the oscillator 4, and the voltages received by detectors 5a and 5b, which are detection units, are passed through buffers and rectified by rectifiers 7a and 7b, respectively. Figure 2 <b), (c
) shows a straight line part and a cross part, but this is a guide with a width of 5 cm, and the cross part has the same guide width, and the horizontal branches corresponding to the width of the left and right sides are 15C1l each. Figures (b) and (c)
The operation of the two methods will be explained based on the differences. First, Figure 1 (
The position marker detection method using the configuration a) will be described.

The output of the rectifier is the linear part (Fig. 2 (b)) and the output of the rectifier (Fig. 2 (a)
The letters a and b change to d and e in the cross section (Fig. 2 (C)). Therefore, d is larger than the maximum value of a and b, and
A comparison level is set lower than the central intersection of e, and if both detection parts exceed the comparison level, it is determined that it is a cross. In the output example shown in FIG. 2 (a>), the maximum value of a and b is 2.2V, and the output at the center of the cross section of the guide, that is, the intersection of d and e, is approximately 3. Therefore, the comparison level is set to, for example, 2. When set to 5V, 30mm left and right from the center of the cross section is the area where the inertial force outputs d and e of the two detectors both exceed the comparison level.Therefore, in this case, if the meandering is within BC11 on the left and right, the position can be changed. Can be reliably detected.

Next, as another detection method, a position marker detection method using the configuration shown in FIG. 1(b) will be described. The rectified outputs of the two systems are input 12 to an adder 8 to obtain a sum signal, which is compared with a predetermined reference voltage by a level comparator 9 to determine its magnitude and output as an ON-OFF signal. In the output example of FIG. 2(a), C is the sum signal of the detector outputs a and b in the straight line section. The sum signal became almost constant within 30m to the left and right of the center. Next, FIG. 3 shows a region where a cross is detected and the output is turned on when the reference voltage is set to a certain value.

The shaded area in the figure is the area where the output is turned on. With the above method, it was possible to detect the position within 3011111 left and right, but with this method using a sum signal, the position can be detected within 50 left and right from the center of the cross.
It can be seen that sufficient detection is possible even at distances of mm or more. Also, even if the position is shifted by 30 degrees to the left and right in the direction of movement of the sensor, the O
The deviation in the timing of reaching N is only about ±5II11. From this, it can be said that using the sum signal for position marker detection is robust against meandering. In particular, when the stop position accuracy is in the intermediate range, this method has a great advantage because the detection accuracy does not change much with meandering. Normally, the sum signal has a region in which there is little change within a certain range from the center of the guide, and in this rounded level comparison, the timing deviation when 0N-OFF is taken is kept small. If the sizes of the sensor and guide are appropriately selected, the sum signal can be made constant as shown in FIG. However, it goes without saying that even if it is not completely constant, it is sufficient for practical purposes.

As a position marker, we have shown one that forms a cross with the same width as the guide, but this cross position marker corresponds to a crossroads at a branch point and can be used to directly branch without using a conventional branch marker. can be detected. It can also be used as is as a stop marker to indicate the stopping point. The size and shape of the position marker are not limited to the examples shown here, but the output of the detectors 1a and lb on the position marker must be sufficiently higher than that on the guide, that is, it must be larger than a certain level. Any shape may be used as long as it is a position marker. In addition, regarding the size of the left and right protruding parts of the marker part, it is sufficient to increase the sensitivity involved in the detector at that location, so it is possible to increase the thickness and increase the sensitivity. It is also possible to use ferrite with a high value as a position marker. - Examples of position markers that cause an increase in the output of the detector have been shown above, but in essence, if there is a change in the detection output, it will be fine if the guide is cut or the width is narrowed, or if the thickness is reduced. Alternatively, even when Ferrite I- with low magnetic permeability is used, the position can be detected by appropriately setting the comparison level.

(Effects of the Invention) As described above, by using the position marker and the position marker detection method of the present invention, various dedicated markers and marker sensors are not required, and the costs associated with course installation can be significantly reduced. Furthermore, since the guide sensor counts the branch points themselves, unstable factors such as branch marker installation errors and marker sensor mounting position errors can be eliminated. Further, the position marker detection method using the sum signal has the effect of dramatically improving the position marker detection accuracy during meandering.

[Brief explanation of drawings]

FIGS. 1(a) and (b) are block diagrams of the configuration used in the method of the present invention, FIG. 2(a) is a diagram showing the output characteristics obtained in the detection section of the sensor and the characteristics of the sum of 100 outputs, Figure 2(b)
, (c) is a diagram showing the relationship between the sensor and the straight cross section of the guide, FIG. 3 is a diagram showing the operating area of position marker detection, and FIG. 4 is a diagram showing the output characteristics of a conventional guide sensor. . 1... Sensor la, lb... Detection section 2...
・Guide LL 4 Lower J stain 1 μJ (V) LC) Ln ″; Ir 2 Figure sensor position (a) Straight section Cross section (b) (C) O 3 Port

Claims (7)

[Claims] (1) A guide sensor mounted on the vehicle body is equipped with at least two detection parts for detecting a band-shaped guide provided on the road surface, and in the band-shaped guide, a part of the guide is made of a different shape or material. A method for detecting a position marker, characterized in that when a guide sensor passes over the position marker, the position is detected by a change in output from both detection parts. (2) The position marker detection method according to claim 1, wherein the position marker is detected using a sum signal of the outputs of both detection sections. (3) A position marker provided on a belt-shaped guide,
A position marker characterized in that a portion of the guide is provided with a different shape or material. (4) The position marker according to claim 3, wherein a part of the guide is wide in the width direction. (5) The position marker according to claim 3, wherein a portion of the guide is cut off to create a gap. (6) A magnetic material for the guide, a magnetic sensor is used for the guide sensor, and the thickness of a part of the guide is changed.
A position marker according to claim 3. (7) The position marker according to claim 3, wherein a magnetic material is used for the guide, a magnetic sensor is used for the guide sensor, and a part of the guide is made of a material with different magnetic permeability.