JPH04346107A - Light guide line detection device - Google Patents

Abstract

PURPOSE:To precisely detect a light guide line for guiding an unmanned vehicle. CONSTITUTION:A line sensor 4 receives light reflected by a road surface 1 and a light reflecting tape 2 and outputs a line sensor signal A whose value corresponds to the quantity of light reception. This line sensor signal A is compared by a comparator 6 with a threshold level and converted into a binary- coded signal. A position computing element 7 operates the position of the light reflecting tape 2 from the width and position of a high-level section of the binary-coded signal. In this case, if there is a part or metal piece with a high reflection factor on the road surface 1, binary-coded signals corresponding to them are ignored. Even if the light reflecting tape 2 becomes narrow in reflection width owing to damage, etc., the binary-coded signal corresponding to the light reflecting tape 2 is obtained to find the tape position.

Description

[Detailed description of the invention]

0001

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a light guide line detection device that is capable of accurately detecting a light guide line used to guide an unmanned vehicle.

0002

2. Description of the Related Art Unmanned vehicles are devices that travel along routes in various factories, warehouses, offices, etc. to transport parts, products, small items, etc. A light guidance method is one method for guiding an unmanned vehicle along a driving route. In the light guidance method, white lines are drawn on the road surface or light-reflective tape is pasted, and the unmanned vehicle's optical sensor detects the white lines and light-reflective tape.
The vehicle will run unmanned along a light-reflecting tape (hereinafter both will be collectively referred to as the "light guide line").

[0003] Conventional optical guidance systems use photodiodes and light emitting diodes as optical sensors. In other words, an optical sensor is used in which a plurality of photodiodes are linearly arranged in the width direction of the unmanned vehicle, and a plurality of light emitting diodes are arranged linearly in the vehicle width direction. and,
Each light emitting diode emits light toward the road surface, and each photodiode receives light reflected from the road surface and the light guide line. In this case, the light reflected from the light guide line has a higher light intensity than the light reflected from the road surface. Therefore, the output of the photodiode that receives the light reflected by the light guide line will be higher than the output of other photodiodes, so by detecting which photodiode has the highest output, the output of the light guide line can be determined. The location can be determined.

0004

[Problem to be Solved by the Invention] However, in the conventional technology, when there are highly reflective parts on the road surface or metal pieces with high reflectance, it is impossible to distinguish between these parts and the light guide line. , it sometimes malfunctioned. Furthermore, if the light guide line becomes dirty or the width of the damaged light guide line becomes narrow, there is a risk that the light guide line cannot be detected.

SUMMARY OF THE INVENTION In view of the above-mentioned prior art, it is an object of the present invention to provide a light guide line detection device that can accurately detect light guide lines.

[0006]

[Means for Solving the Problems] The configuration of the present invention that solves the above problems is provided in an unmanned vehicle that runs along a light guide line installed on the road surface, and is configured to reflect light reflected from the road surface and the light guide line. a line sensor that receives light and outputs a line sensor signal in which a charge having a value corresponding to the amount of received light is sequentially read from each element; a comparator that binarizes the line sensor signal and outputs a binary signal; It is determined whether the width of the high level section of the binary signal is within the range between the predetermined upper limit width and lower limit width, and When the width is outside the range, calculate the position of the light guiding line by calculating based on the binary signal of the high level section at this time, and check that the width of the high level section of the binary signal is the width within the range. When there is an interval where
The light guiding line is calculated based on the binary signal whose high level section width is outside the above range, and ignores the binary signal whose high level section width is outside the above range. A position calculator for calculating a position.

[0007]

[Operation] When there are highly reflective parts on the road surface or metal pieces with high reflectance, the position of the light guide line is calculated by ignoring the binary signals corresponding to these parts, and the position of the light guide line is calculated to prevent damage etc. Even if the width of the light reflecting tape becomes narrower, the position of the light guide line is calculated by capturing the signal corresponding to the light reflected by the light reflecting tape at this time.

[0008]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Examples of the present invention will be described below in detail with reference to the drawings. FIG. 1 is a block diagram showing an embodiment of the present invention, and FIG. 2 is a plan view showing an unmanned vehicle to which the present invention is applied. As shown in both figures, a road surface 1 is provided with a light reflective tape 2 serving as a light guiding line, and an unmanned vehicle 3 is provided with a line sensor 4 having CCDs arranged in a straight line. The light emitted from the unmanned vehicle 3 side and reflected by the road surface 1 and the light reflective tape 2 is received by the line sensor 4, and the charges of the n photoelectric conversion elements (CCD) of the line sensor 4 are as follows.
The readout circuit 5 sequentially reads out the elements from the first (eg, leftmost) element to the nth (eg, rightmost) element. The read voltage signal becomes a line sensor signal A (see FIG. 3) and is sent to the comparator 6. The level of the line sensor signal A is high in a portion corresponding to the light reflective tape 2 and low in a portion corresponding to the road surface 1.

The comparator 6 has a threshold belt V.
t is set, and the line sensor signal A is binarized based on this threshold level Vt to become a binarized signal B (see FIG. 4). Binarized signal B is C
The signal is sent to a position calculator 7 composed of a PU or the like.

The position calculator 7 is set with an upper limit width WU, which is the width of the light reflective tape 2 increased by 5%, and a lower limit width WD, which is the width of the light reflective tape 2 reduced by 5%. When the binarized signal B is input to the position calculator 7, it is first determined whether the width WB of the high level section of the binarized signal B falls between the upper limit width WU and the lower limit width WD. When the width WB is larger than the width WU or smaller than the width WD, that portion of the binarized signal is ignored, and the position calculation described below is performed using the signal in the high level section satisfying WD≦WB≦WU. Note that in the entire interval of the binarized signal B, WD ≦
When there is no high level section satisfying WB1≦WU, the high level section at that time is not ignored, but the position is calculated using the signal of this high level section.

[0011] Here, position calculation will be explained. Figure 4
When a binary signal B as shown in is input and the width WB1 of the high level section satisfies WD≦WB1≦WU, the position of the light reflective tape 2 is calculated using the following equation (1). .

0012

[Math 1]

If there is a highly reflective part on the road surface 1 or a highly reflective metal piece, the line sensor signal A becomes as shown in FIG. 5(a). In FIG. 5A, a portion α corresponds to a metal piece or the like, and a portion β corresponds to the light reflective tape 2. In FIG. When the line sensor signal A shown in FIG. 5(a) is binarized, a binarized signal B shown in FIG. 5(b) is obtained. In FIG. 5(b), the width WB2 of the first high level section is smaller than the width WD, and the width WB3 of the second high level section.
satisfies WB≦WB3≦WU, so the arithmetic unit 7
The position of the light reflective tape 2 is calculated using the data shown in FIG. 5(c) in which the first high level section is ignored and only the second high level section exists, and the equation (1) shown above. Therefore, even if there are metal pieces, ignore them and use the light reflective tape 2.
can accurately detect the position of

If the light reflective tape 2 is dirty or damaged and a portion of the tape that actually contributes to reflection is chipped, the line sensor signal A becomes as shown in FIG. 6(a). Figure 6 (a
), the part γ corresponds to the part missing due to dirt. When the line sensor signal a shown in FIG. 6(a) is binarized, a binarized signal B shown in FIG. 6(b) is obtained. Figure 6 (
In b), the width WB4 of the high level section is smaller than the width WD, so it is ignored at first, but then it is shown in Fig. 6(c).
As shown in , there is no high level section in all sections. Therefore, at this time, as shown in FIG. 6(d), the width W
Even if B4 is smaller than the width WD, the light reflective tape 2 can be
Calculate the position of. Therefore, even if the reflective surface width of the light reflective tape 2 becomes small due to dirt or damage, the position of the light reflective tape 2 can be accurately detected.

In the above embodiment, a light reflecting tape is used as the light guide line, but even when a white line is used, the position of the white line can be detected accurately according to the present invention.

[0016]

[Effects of the Invention] As specifically explained above in conjunction with the embodiments, according to the present invention, even if there are parts or objects with high reflectivity on the road surface, the reflection width will be narrow due to dirt or damage on the light guiding line. However, the position of the light guide line can be detected accurately.

[Brief explanation of the drawing]

FIG. 1 is a block diagram showing an embodiment of the present invention.

FIG. 2 is a plan view showing an unmanned vehicle to which the present invention is applied.

FIG. 3 is a waveform diagram showing a line sensor signal.

FIG. 4 is a waveform diagram showing a binary signal.

FIG. 5 is a waveform diagram showing a signal waveform when there is a reflective object or the like on the road surface.

FIG. 6 is a waveform diagram showing signal waveforms when the light reflective tape becomes dirty.

[Explanation of symbols]

1 Road surface 2. Light reflective tape 3. Unmanned vehicle 4 Line sensor 5 Readout circuit 6 Comparison circuit 7 Position calculator A Line sensor signal B Binarized signal Vt threshold level

Claims (1)

[Claims] [Claim 1] An unmanned vehicle that travels along a light guide line installed on the road surface is equipped with a device that receives light reflected from the road surface and the light guide line, and charges a value corresponding to the amount of light received from each element. A line sensor that outputs line sensor signals read out in sequence, a comparator that binarizes the line sensor signal and outputs a binary signal, and a predetermined upper limit for the width of the high level section of the binary signal. It is determined whether the width is within the range between the width and the lower limit width, and if the width of the high level section is outside the range in the entire section of the binarized signal, the width of the high level section at this time is determined. The position of the light guide line is determined by calculation based on the binarized signal, and if there is a section where the width of the high level section of the binarized signal is within the above range, the width of the high level section is outside the above range. a position calculator for calculating the position of the light guiding line by ignoring the binary signal having a width of , and calculating based on the binary signal having a width of the high level section within the width of the above range; A light guiding line detection device comprising: