JPH0441363Y2 - - Google Patents

Description

[Detailed description of the invention] Industrial application field This invention relates to unmanned vehicles used for transporting goods in warehouses, factories, etc. This invention relates to an unmanned vehicle that guides the vehicle while driving.

Conventional technology An optically guided unmanned vehicle (hereinafter simply referred to as an unmanned vehicle) that guides the vehicle while detecting the above-mentioned floor guidelines using an optical sensor.
Conventionally, the guidelines have been to attach a white tape with high light reflectance to the floor surface, or to apply a similar white paint to the floor surface. By using a white color, an optical sensor detects the difference in the amount of reflected light from the floor surface and detects the position of the guideline.

Problems to be Solved by the Invention Among unmanned vehicles to which the optical guidance method described above is applied, for example, three-wheeled unmanned vehicles, there are some in which the wheels of the vehicle travel while following guidelines. If the wheels of an unmanned vehicle travel on the guideline many times, the line becomes dirty or faded, making it impossible to reliably detect the position of the line. In order to avoid such drawbacks, it has been necessary to frequently clean the inside of the factory to prevent dirt from adhering to the guideline, or to perform extremely troublesome maintenance such as frequently cleaning the guideline from dirt.

Means to Solve the Problem This invention divides the guideline in the optical guidance system into a plurality of bands along the direction of movement of the unmanned vehicle, and at least one of these bands is colored with a dark color for wheel running. The other band is a white band for detection.

Function The wheels of the unmanned vehicle run on a dark colored band, and the optical sensor detects another white colored band, and the unmanned vehicle is guided based on the detected results.

Embodiment FIG. 1 is a schematic plan view of a three-wheeled unmanned vehicle 1 as an example of an unmanned vehicle, in which 2 is a drive wheel that is directly connected to a travel motor 3 and steers around a vertical axis 4, and 5 is a drive wheel that rotates around a vertical axis 4. Sprocket 6 fixed to
and a steering motor 8 connected to the sprocket 6 by a chain 7.
1 is a driven wheel, and 11 is an optical sensor to be described later. 12 indicates a guideline, and the line 12 is divided into three bands in the longitudinal direction, of which the central band 12a is a dark color, for example, black, and the two bands 12b and 12c on both sides are white. The color of the system, for example, white. Above center band 12a
The width of the drive wheel 2 is larger than the width of the drive wheel 2. The guideline 12 is formed by pasting tape or applying paint. An arrow 10 indicates the direction of movement of the unmanned vehicle 1.

Next, to explain the structure of the optical sensor 11 of this example, as shown in FIGS. 2 to 5, the sensor of this example has a substantially rectangular base 13.
16 holes 14 and 15 are drilled in two rows in the longitudinal direction,
In the holes 14 and 15, infrared light emitting diodes 16 as a light source are inserted in one row, and phototransistors 17 as light receiving elements are inserted in the other row. 18 is a mounting block to the vehicle body 1, 19 is a printed circuit board, and 21 is a red filter. Third
The figure is a cross-sectional view taken along the line A-A in FIG.
2a is present, and FIG. 4 also shows the case where B-
It is a sectional view taken along the line B, and shows a case where one of the bands 12c on both sides is present directly below the light receiving element 17.

FIG. 5 shows the circuit of the infrared light emitting diode 16 and phototransistor 17, and shows the voltage (Vp)
Light (L) is emitted by applying the amount of light, and the reflected light from the floor surface or the guideline is incident on the phototransistor 17, and a voltage proportional to the amount of the incident light is output (OUT).

In this way, the output voltage from each phototransistor 17 changes in relation to the amount of light reflected from the floor directly below the phototransistor 17, and the magnitude of the output voltage indirectly causes a difference in the light reflectance of the floor. In other words, it is designed to detect whether it is a floor surface or a guideline.

Next, a method for detecting this guideline position will be explained.

That is, as shown in FIG. 6, each phototransistor 17 is connected to an analog multiplexer 22,
It is connected to a computer 25 mounted on the vehicle body 1 via an amplifier 23 and an A/D converter 24, and the computer 25 is connected to each interface 2.
The computer 25 calculates the guideline position by arithmetic analysis of the output signal of the phototransistor 17 using a method described in detail later, and calculates the calculated value. Based on this, the traveling motor 3 or steering motor 8 is appropriately driven to guide the vehicle. 31, 32, and 33 are the RAM, CPU, and RAM in the computer 25, respectively.
It is ROM.

That is, the multiplexer 22 is
is switched as appropriate, and the output voltage from the phototransistor 17 at one end of the sensor is sequentially inputted to the A/D conversion circuit, and the output voltage is converted into a corresponding digital value and stored in the RAM 31 in the computer 25.
is stored in

That is, for example, in order from the end of the sensor 11, a voltage of 3 volts is output from the first phototransistor 17 through the amplifier 23 and A/D conversion, a voltage of 3.5 volts is output from the second phototransistor 17, and a voltage of 3.5 volts is output from the second phototransistor 17.
Each voltage value, such as 4 volts from the phototransistor 17, is temporarily stored in the memory 31, and the stored voltage values are processed as follows.

That is, when the stored voltage value, that is, the amount of light received is expressed in a bar graph, it becomes a bar line with white circles in FIG. 8, and the numbers on the horizontal axis of the graph indicate the position of each phototransistor (see FIG. 7). The vertical axis shows the amount of light received, but the bar line with white circles is a value based on the actual amount of light received, so it does not faithfully reflect the effects of locally bright areas on the floor, highly reflective dust, etc. , even in areas other than the guideline, there may be cases where a locally high value is shown (value 14 in Figure 8).In order to eliminate this effect, first the voltage value obtained as above is Smooth as follows.

That is, as shown in FIG.
The actual voltage value from the phototransistor No. 1 and the phototransistor No. 16, that is, the transistors across the sensor, are each detected to be 1.5 volts.
The values from are compared with the actual voltage values from the phototransistors (No. 2 and No. 15) located one inside, respectively, and the smaller value is taken as the smoothed voltage value at each end. For example, when comparing the first and second actual voltage values, the first value is smaller, so the first smoothed voltage value becomes the first actual voltage value.

In addition, each phototransistor 17 of No. 2 to No. 15
To smooth the voltage value, the values on both sides are compared with the three voltage values, and the second largest value is taken as the smoothed voltage value of the phototransistor. For example, the smoothed voltage of number 14 is equal to the smoothed voltage of number 13
Comparing the three values from 15th to 15th, the second largest value is the 13th value.

The smoothed values are shown as bars with black circles in FIG. Note that the smoothing method is not limited to the above-mentioned method, and for example, a method of taking the average value of the values at both ends thereof can be applied.

Next, an appropriate threshold value (T) is set from all the smoothed values for each phototransistor 17 obtained by the above calculation.

As is clear from FIGS. 7 and 8, in the actual voltage values (white circles) before smoothing, the white bands 12b, 1
Phototransistor positions other than the 2c position (14th
There were also values exceeding the threshold (T) in the phototransistors (Nos. 2 to 3 and No. 9) only in the white bands 12b and 12c after smoothing
. . . No. 11) exceeds the threshold (T), making it possible to accurately detect the positions of the white bands 12b and 12c.

Then, the center of the guideline is determined based on the threshold value (T) determined by the above calculation and each value after smoothing.

That is, based on each of the above-mentioned smoothing values and threshold (T), for each phototransistor (No. 1 to 16), those whose smoothed values exceed the threshold (T) are set to "1", and the threshold (T) is set to "1". ) is binarized (Fig. 9), in which those that do not exceed 0 are set to ``0''. For example, in the above example, numbers 2 to 4, numbers 9 to 11
"1" for phototransistor 17
However, "0" is given to phototransistors 17 other than those mentioned above.

Then, the value (V), "0" or "1" given by the above binarization, is given a weight (W) regarding the position of each phototransistor (No. 1 to No. 16).
(In other words, for example, numbers that increase from the left end to the right end, in this example 0 to 30) are multiplied, and the product value is the sum of all values after binarization,
That is, the center of the guideline is found by dividing by the number of phototransistors 17 whose values after smoothing exceed the threshold.

That is, in the case of the above example, as shown in FIG. 9, the first phototransistor 17 has "0".
However, the second phototransistor 17 has "2".
However, ``30'' is given as the position weight (W) to the 16th phototransistor 17, and the center position of the guideline is calculated as the position weight in the following manner.

Σ (position weight) x (value after binarization) / Σ (value after binarization) = (0 x 0) + (2 x 1) + (4 x 1) + (6 x 1)
+(8×0)+……/0+1+1+1+0+0+0+…
... ... + (30 x 0) / ... +0 = 11 Therefore, in the above example, the position weight is "11", that is, the 6th and 7th in the sensor 11.
It is detected that the center of the guideline is located directly below the midpoint of the phototransistor number.

As above, (position weight) × (value after binarization)
By dividing the sum of (values after binarization) by the sum of (values after binarization), the sum of (values after binarization) corresponds to the width of the guideline, so regardless of the fluctuation of the guideline width, , it is possible to accurately detect the center and position of the guideline, and it is also possible to reduce the influence of the appearance of locally high values that cannot be eliminated even by the above-mentioned smoothing process.

Then, once the center position of the guideline is calculated in the computer 25 as described above,
Next, when the amount of deviation is small, the output to the steering motor 8 is temporarily turned off, and when the amount of deviation is large, the output to the steering motor 8 is turned off to the left or right depending on the direction of deviation of the guideline position with respect to the sensor 11. Rotation is driven in the direction to correct the deviation.

In other words, for example, in the above example, the detected value is "11" and the position weight of the center of sensor 11 is "15", so in Fig. 7, sensor 11, that is, vehicle body 1, is shifted to the right. , the steering motor 8 is rotated in a direction to move the vehicle body 1 to the left. If the vehicle body 1 is shifted to the left,
Of course, the steering motor 8 is rotated in the opposite direction.

As described above, in this embodiment, the voltage of each phototransistor is smoothed, and the central position of the guideline relative to the optical sensor is detected by the aforementioned calculation processing to guide the unmanned vehicle. The guideline can be reliably detected without being affected by dust or highly reflective dust.

FIGS. 10 and 11 respectively show other embodiments of the present invention. The guideline 40 shown in FIG. 10 is divided into two bands in the longitudinal direction, and one band 40a is a dark color.
Wheel 2 runs on a. The other band 40b has a white color and is detected by the optical sensor 11. The guideline 40 of this embodiment can have a width smaller than that of the guideline described above.

The guideline 50 of the embodiment shown in FIG. 11 is divided into five bands in the direction of travel, with the central band 50a, the bands 50b and 50c at both ends having a dark color, and the remaining two bands 50d. , 50e are white-based colors. The wheels 2 run on the central band 50a, and the optical sensor 11 runs on the two white bands 50a.
d, 50e are detected. According to the guidelines of this embodiment, only the reflected light from the whiter bands 50d and 50e stands out, so there is no detection error, and it can be used even if the floor surface itself in the factory is white in color.

Effects of the invention As explained above, in the invention, the guideline is divided into a plurality of bands, at least one of which is a dark-colored band for wheel running, and the other is a white-colored band for detection. Since the wheels were made to run on the dark color band, the white color band was not stained or faded. Therefore, the guideline could be reliably detected without frequent cleaning.

[Brief explanation of the drawing]

Fig. 1 is a schematic plan view showing an example of an unmanned vehicle, Fig. 2 is a plan view of an optical sensor, and Fig. 3 and 4
The figures are respectively a cross-sectional view taken along line A-A and line B-B in Figure 2, Figure 5 is a circuit diagram, and Figure 6 is a block diagram showing the connections of the computer, optical sensor, etc. on the unmanned vehicle. Figure 7 is a schematic diagram showing the positional relationship between the phototransistor of the optical sensor and the guideline, Figure 8 is a bar graph showing the actual amount of light received by each phototransistor and the value after smoothing, and Figure 9 is a schematic diagram showing the positional relationship between the phototransistor of the optical sensor and the guideline. A schematic diagram showing position weights and binarized values for phototransistors, Figures 10 and 11 are diagrams showing other embodiments of the present invention, respectively, and Figure 10 shows a guideline divided into two bands. The plan view, FIG. 11, is a plan view showing the guideline divided into five bands. 1...Unmanned vehicle, 11...Optical sensor,
12, 40, 50...Guideline, 12a, 4
0a, 50a, 50b, 50c...Dark color band, 12b, 12c, 40b, 50d, 50e...
...White band, F...Floor surface.

Claims (1)

[Scope of Claim for Utility Model Registration] A guideline for an unmanned vehicle in which at least one of the wheels travels on the guideline while detecting the guideline on the floor using an optical sensor, the guideline being a guideline for an unmanned vehicle that runs on the guideline along the direction of travel of the unmanned vehicle. A guideline for an unmanned vehicle, characterized in that it is divided into a plurality of bands, at least one of which is a dark-colored band for wheel running, and the other band is a white-colored band for detection.