JPS61819A - Guide system of unmanned truck - Google Patents

Abstract

PURPOSE:To detect a guide line with high accuracy and to secure the smooth guidance of an unmanned truck by smoothing the light quantity received by each photodetecting element of an optical sensor through comparison with the light quantity received by an adjacent photodetecting element and detecting the guide line from the value obtained after smoothing. CONSTITUTION:A multiplexer 22 is properly switched by a selection command 29 given from a computer 25, and the output voltage sent from a phototransistor TR17 set at an end of a sensor 11 is converted into the corresponding digital value and stored in an RAM31. The values of the TRs 17 set at both ends of a sensor are set equal to the value obtained by averaging the actual voltage levels of the TRs 17 which are adjacent to each other at the inner side. While the values of other TRs 17 are set equal to the value obtained by averaging the values of the TRs 17 adjacent to each other at both sides. Then a smoothing operation is carried out. The value obtained after said smoothing operation is binary-coded based on the threshold value set properly. Then the prescribed arithmetic processing is carried out to obtain the center of a guide line. Based on this guide line, a drive motor 3 or a steering motor 8 is driven for guidance of an unmanned truck.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a guidance method for an unmanned vehicle that guides the vehicle while detecting guidelines on the floor using an optical sensor.

The method of detecting the guideline on the floor using the optical sensor and guiding the vehicle based on the detected value is generally called an optical guidance method, and the guideline position is detected based on the difference in amount. Even if the position is outside the guideline, strong reflected light may unexpectedly enter the light receiving element outside the guideline position due to the influence of a locally high reflectance part on the floor or a foreign object with high reflectance. If the received light amount value is judged as a guideline, the unmanned vehicle will naturally fall outside the official guideline.

Therefore, the present invention smoothes the received light amount value received by each light receiving element of an optical sensor by comparing it with the received light amount value of one or more adjacent light receiving elements, and detects a guideline using the smoothed value. By doing so, the above-mentioned drawbacks are solved, and examples will be described below based on the drawings.

That is, FIG. 1 is a schematic plan view of a three-wheeled unmanned vehicle (1) as an example of an unmanned vehicle, and (2) is directly connected to a travel motor (3) and rotates by steering around a vertical axis (4). The drive wheel (5) has a sprocket (6) fixed to the vertical shaft (4) and a chain (6) attached to the sprocket (6).
7) A steering device consisting of a connected steering motor (8), (9) is a driven wheel, and in this unmanned vehicle (1), an optical system is installed, especially in a position biased to the front left side of the driving wheel (2). The type sensor (11) is installed. This unmanned vehicle (1) uses an optical sensor (1) as described above.
1) is installed on the side of the drive wheel (2), and the guideline (12) is placed on the floor by pasting tape or applying white paint to the center of the vehicle body (1). Since the vehicle runs while looking at a more biased position, the wheels (2) do not move on the guideline (12) and the guideline (12) can be prevented from getting dirty.

Next, to explain the structure of the optical sensor (11) of this example, as shown in FIGS.
Drill 16 holes (14) (15) in a row, and
4) An infrared light emitting diode (16) as a light source is inserted in one column of (15), and a phototransistor (17) as a light receiving element is inserted in the other column. (18
) is a mounting block to the vehicle body (1), (19) is a printed circuit board, (21) is a red filter, and the infrared light emitting diode (16) is based on one with a wide directivity (approximately 60 degrees) ( 13), and the phototransistor (17) with a narrow directivity (approximately 20 degrees) is loaded perpendicularly to the substrate (13) so that it is irradiated by the infrared light emitting diode (16). Directly reflected light (L'l) reflected from the floor (F) or guideline (12)
(L'2) is prevented from directly entering the phototransistor (17) [7] to eliminate the influence of the gloss of the floor surface (Section 3.4).

Figure 5 shows the circuit of the infrared light emitting diode (16) and phototransistor (17), where light (L) is emitted by applying a voltage (Vp), and the reflected light from the floor or guideline is reflected by the phototransistor. (17), a voltage approximately proportional to the amount of incident light is output (OU
T) be done.

In this way, the output voltage from each phototransistor (17) changes approximately in proportion to the amount of light reflected from the floor directly below the phototransistor (17), and the magnitude of the output voltage indirectly changes the amount of light on the floor. It is designed to detect the difference in reflectance, that is, whether it is a floor surface or a guideline.Next, the method for detecting the guideline position will be explained.

That is, as shown in FIG. 6, each phototransistor (17) is connected to a computer ( 25), and the computer (25) is connected to the traveling motor (3) and the steering motor (8) via respective interfaces (26) and (27), in a manner to be described in detail later. A computer (25) performs arithmetic analysis on the output signal of the phototransistor (17) to calculate the guideline position, and based on the calculated value, drives the travel motor (3) or steering motor (8) as appropriate to perform guided travel. It has become. (31), (32), and (33) are the RAM, CPU, and ROM in the computer (25), respectively.
It is.

That is, the multiplexer (22) is appropriately switched by the phototransistor selection command (29) from the computer (25), and the phototransistor (
The output voltage from the converter 17) is input to the A/D converter, and the output voltage is converted into a corresponding digital value and stored in the RAM (31) in the computer (25).

That is, for example, starting 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, and a voltage of 3 volts is output from the second phototransistor (17). .5 volts, 4 volts from the third phototransistor (17), etc. Each voltage value is temporarily stored in the memory (31), and the stored voltage value is used for the next one. Process it like this.

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. , may show a locally high value even in areas other than the guideline (the 14th value in Figure 8).In order to eliminate this influence, the voltage value obtained as above is
First, smooth as follows.

That is, as shown in FIG. 8, the actual voltage value from the No. 1 phototransistor and the No. 16 phototransistor, that is, the transistors at both ends of the sensor, is detected as 15 volts, respectively. The values from each phototransistor (17) are averaged with the actual voltage values from the phototransistors (No. 2 and No. 15) one inside, and the value is calculated as the smoothed value at each end. It is a voltage value.

In other words, if the actual value of the second phototransistor is, for example, 2.3 volts, then (1,5+2.3)/2=1
．． 9 gives a smoothed value of 19 for the 1st phototransistor, and if the actual value of the 15th phototransistor is, for example, 21 volts, then (2,1+1.5)
/ 2 = 1.8, 1.8 is obtained as the smoothed value of the 16th phototransistor.

Moreover, regarding the smoothing of the voltage value of each phototransistor (17) No. 2 to No. 15, the average value of the values on both sides thereof is taken.

In other words, for example, phototransistor No. 14 (17)
The actual voltage value from the 13th
．． If the values of number 15 are 27 volts and 2.0 volts, then (3, 4 + 2.7 + 2.0) / 3 =
According to 2.7, the 14th phototransistor (17)
A smoothed value of 27 is obtained, and the above calculation is performed for each phototransistor to smooth all values.

The smoothed values are shown as bars with black circles in FIG.

Then, an appropriate value ('r) is set from all the smoothed values for each phototransistor (17) obtained by the above calculation.

As is clear from Fig. 7.8, the actual voltage value (white circle) before smoothing also has both values (T ), but after smoothing, only the values of the phototransistors (Nos. 5 to 8) at the guideline position exceed both values (T), making it possible to accurately detect the guideline position. ing.

Then, the center of the guideline is determined based on the 1 extreme value (T) determined by the above calculation and each value after smoothing.

That is, based on each of the above smoothed values and one-station value (T), for each phototransistor (Nos. 1 to 16), if the smoothed value exceeds both values ('r), it is set as "1". , 1 is given to the phototransistors (17) whose numbers do not exceed the orchid value (T), and "1" is given to the phototransistors (17) numbered 5 to 8.

Then, the value (■) “O” given by the above binarization
Or "1" for each phototransistor (No. 1 to 16)
The weight (b) (i.e., a number that increases as you go from the leftmost edge to the rightmost edge, in this example, 0 to 30) is multiplied by the weight (b) related to the position of the The center of the guideline is found by dividing by the sum of .

In other words, in the case of the above example, as shown in FIG.
The number phototransistor (17) has a "0", the second phototransistor (17) has a "2", etc.
・"30" for the 16th phototransistor (17)
is given as the position weight (b), and the center position of the guideline is calculated as the position weight as follows.

Σ (value after binarization) ωxo) + (2xO) + + (8xl) +
(10xl) + (12xl) + (14x1) ten...
...+(30Xo)0+O10...+1+
1+1+100+ ・・・・・・・+0=11 Therefore, in the above example, the point whose position weight is “11”,
In other words, the sensor (11) detects that the center of the guideline is located directly below the midpoint between the sixth and seventh phototransistors.

As mentioned above, by dividing the sum of (position weight) x (value after binarization) by the sum of (value after binarization), the sum of (value after binarization) is equivalent to the width of the guideline, so regardless of the variation in the guideline width,
The center position of the guideline can be detected accurately and is not eliminated even by the above-mentioned smoothing process. The influence of locally appearing high values can be reduced.

That is, for example, in FIG. 8, suppose that the smoothed value of the 14th phototransistor (17) other than the guideline position exceeds the outer value (T), and even after binarization, the 14th phototransistor (17)
Assuming that rlJ is given to phototransistor No. 4, the calculation to calculate the center of the guideline mentioned above is (8X1) + (IOXI) + (12X1) + (1
4X1) + (26X1), and since the detected value "14" corresponds to the 8th phototransistor position in the sensor (11), the detected value is the width of the guideline (
It remains within the 5th to 8th phototransistor positions), and the local influence of the 14th phototransistor position is reduced.

Once the center position of the guideline has been calculated in the computer (25) as described above, the output to the steering motor (8) is temporarily turned off when the amount of deviation is small. When it is large, the sensor (
11) Depending on the direction of deviation of the guideline position,
The steering motor (8) is driven to rotate either left or right in a direction to correct the above-mentioned deviation (FIG. 10).

That is, for example, in the above example, the detected value is "11" and the position weight of the center of the sensor (11) is 1 - "15", so in Fig. 7 the sensor (11), that is, the vehicle body (1) is on the right. As a result, the steering motor (8) is rotated in a direction to move the vehicle body (1) to the left. If the vehicle body (1) is displaced to the left, the steering motor (8) is of course rotated in the opposite direction.

The above process is shown in a flowchart as shown in Fig. 10, and in this embodiment, from "Start" to "Turn the steering wheel to the left" or "Turn the steering wheel to the right" and then again to "Storing the amount of received light...into the memory". The cycle time to return to Drive according to the guidelines.

In addition, at the point where the guideline is interrupted, the onboard computer (25) determines the interruption and stops the unmanned vehicle, but the computer (25)'s ROM (33)
), if the driving information after the guideline was interrupted (information on driving speed, steering angle, etc. stored as a function of the distance traveled) is stored, the unmanned vehicle will be able to move around the interrupted part of the guideline. The vehicle can also drive automatically based on the above driving information.

As is clear from the above description, the present invention smoothes the amount of light received by each light receiving element of an optical sensor by comparing it with the value of the amount of light received by one or more adjacent light receiving elements, and Since the guideline is detected based on the value after conversion, even if an unexpectedly strong reflected light beam hits a light receiving element other than the guideline position, this locally high amount of received light will not be judged as the guideline, and therefore unattended operation is possible. The vehicle can also continue to drive normally without deviating from the guidelines.

[Brief explanation of drawings]

Figure 1 is a schematic plan view showing an example of an unmanned vehicle;
The figure is a circuit diagram, Figure 6 is a block diagram showing the connection of the computer on the unmanned vehicle, optical sensors, etc., 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, Figure 9 is a schematic diagram showing the position weight and binarized value for each phototransistor, and Figure 10 is the processing process. This is a flowchart. (1)...Unmanned vehicle, (2)...Drive wheel, (5)...Steering device, (11)
...Optical sensor, (12)...Guideline, (17)...Phototransistor, CP)...Go to floor surface Fig. 5 77. One, Figure 2, Figure 6, Figure 7, 8th, 9th.

Claims (1)

[Claims] A guidance method for an unmanned vehicle that uses an optical sensor to detect guidelines on the floor while guiding the vehicle,
The value of the amount of light received by each light-receiving element of the optical sensor is smoothed by comparing it with the value of the amount of light received by one or more adjacent light-receiving elements, and the guideline is detected based on the smoothed value. A unique guidance method for unmanned vehicles.