JPS61818A - Guide system of unmanned truck - Google Patents

Abstract

PURPOSE:To secure the smooth guidance of an unmanned truck despite a change of the guide line width by adding the weight given to the photodetecting elements which exceeds the threshold value and dividing the sum of the weight by the number of those photodetecting elements exceeding the threshold value. CONSTITUTION:A multiplexer 22 is switched properly 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 is converted into the corresponding digital value and stored in an RAM31. The stored voltage value is smoothed with all TRs 17, and a proper threshold level is set. Then said voltage value is binary-coded based on the average value and the threshold value. The weight related to the position of each TR17 is applied to the value obtained from the binary coding operation. This product value is divided by the number of TRs 17 whose values obtained after smoothing exceeds the threshold value. Thus the center of a guide line is obtained. Based on this center line, a drive motor 3 or a steering motor 8 is driven to guide 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 guidelines on the floor using the optical sensor and steering the vehicle based on the detected values is generally called an optical guidance method, in which the light emitted from the light source is reflected by the floor surface, and the reflected light is reflected by the floor surface. The guideline position is detected based on the difference in the amount of light received by each light-receiving element, but a method that steers and guides the vehicle based only on the position of the light-receiving element that receives a large amount of light has the following disadvantages. arise.

That is, for example, if the light receiving element at the n-th position to the right or left from the center of the optical sensor receives a large light wind, the steering wheel is turned to the left or right by the value of n multiplied by an appropriate coefficient. In a system where steering is performed by combining the positions of light receiving elements that receive a large amount of light, if the width of the guideline changes along the driving path, the steering angle will not be appropriate and the vehicle may meander or become severely damaged. may deviate from the guidelines. and,
The above problem is not so serious when the kite line is attached to the floor with tape, but it becomes an important problem when the kite line is attached by applying white paint to the floor.

Therefore, the present invention relates to a light-receiving element that exceeds a guideline value for detecting a guideline in an optical sensor, and the weight that is given for the position of the light-receiving element is divided by the number of light-receiving elements that exceed the threshold value. The above drawbacks are solved by detecting the center of the guideline with respect to the optical sensor.Examples will be described below with reference to 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).
A steering device consisting of a power-coupled steering motor (8), (9) being a driven wheel.

In this unmanned vehicle (1), an optical sensor (11) is particularly attached to a position biased toward the front left side of the drive wheel (2). In this unmanned vehicle (1), as described above, the optical sensor (11) detects the position of the guideline (12) laid on the floor outside the position of the drive wheel (2) at a position offset from the center of the vehicle body (1). Wheels (2)
does not move on the guideline (12) and moves on the guideline (1)
2) Contamination can be prevented.

Next, to explain the structure of the optical sensor (11) of this example, as shown in FIGS. 16 holes (14) (15) are drilled in the row, and the holes (
14) 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) has a wide directivity (approximately 60 degrees). (13) At the same time as loading at an angle,
The phototransistor (17) has a narrow directional characteristic (approximately 20
Directly reflected light (L'
1) (L'2) is designed not to directly enter the phototransistor (17) to eliminate the influence of gloss on the floor surface (Fig. 314).

FIG. 5 shows the circuit of the infrared light emitting diode (16) and the phototransistor (17).90 is emitted by applying a voltage (Vp), and the reflected light from the floor or guideline is reflected from the phototransistor (17). ), and a voltage proportional to the amount of 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 reflects the light reflected from the floor. It is designed to detect the difference in rate, that is, whether it is on the floor or on the 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 the vehicle body (
11, and the computer (25) is connected to each interface (25).
6) The said running element=ri(3) via (27).

It is connected to the steering motor (8), and the computer (25) calculates the guideline position by calculating and analyzing the output signal of the phototransistor [17] using a method described in detail later. (3) Alternatively, the steering motor (8) is appropriately driven to guide the vehicle.

(,31X32) (33) are respectively computers (25)
RAM, CPU, and ROM inside.

That is, the multiplexer (22) is appropriately switched by the phototransistor selection command (29) from the computer (25), and the phototransistor (
The output voltages from 17) are sequentially input to the A/D conversion circuit, and the output voltages are converted into corresponding digital values and stored in the RAM (31) in the computer (25).

That is, for example, starting from the end of the sensor (11).

The amplifier (23) is connected to the first phototransistor (17).
) and A/D conversion, a voltage of 3 volts is output from the second phototransistor (17), 3.5 volts from the third phototransistor (17), and 4 volts from the third phototransistor (17).
. . . Each voltage value 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. In some cases, a locally high value may be shown even in a portion other than the guideline (the 14th value in FIG. 8), and this influence should be eliminated.

The voltage value obtained as described above is first smoothed as follows.

That is, as shown in FIG. 8, the actual voltage values from the first and sixteenth phototransistors, that is, the transistors at both ends of the sensor, are each detected to be 1.5 volts. The values from the phototransistors (17) at both ends are 1
The actual voltage values from the inner phototransistors (No. 2 and No. 15) are averaged, and that value is used as the smoothed voltage value at each end. In other words, if the actual value of the second phototransistor is, for example, 23 volts, then
(1,5+2.3)/2=19 gives a smoothing value of 1.9 for the first phototransistor,
If the actual value of phototransistor No. 15 is, for example, 21 volts, then (2,1+1.5)/2-1. ．． 8, the smoothing value of the 16th phototransistor is 1.
8 is obtained.

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, 1For example, the 14th phototransistor (17)
The actual voltage value from the 13th
．． The value of number 15 is 27 volts each.

Assuming it was 20 volts.

(3,4+2.7+2.0)/3=2.7, 27 is obtained as the smoothed value of the 14th phototransistor (17), and the above calculation is performed for each phototransistor to calculate all values. Smoothed values are shown as bars with black circles in FIG.

Then, an appropriate cap value (2) is set from all the smoothed values for each phototransistor (17) obtained by the above calculation.

As is clear from Figure 7.8, the actual voltage values (white circles) before smoothing are at the guideline positions (5th to 8th).
There are values exceeding confidence (1) at other phototransistor positions (No. 14), but after smoothing, only the values of the phototransistors at the guideline position (No. 5 to 8) exceed the estimated value ■. , the guideline position can be accurately detected.

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

That is, based on the above-mentioned smoothed value and equivalent value ■, for each phototransistor (No. 1 to 16), those whose smoothed values exceed the equivalent value (1) are set as "1", and the @ value ■ is set as "1". Regarding the phototransistor (17), which does not exceed rOJ,
For 7), "1" is given.

Then, the value (g) given by the above binarization is "0"
Or "1" for each phototransistor (No. 1 to 16)
The weight W (i.e. 1, for example, a number that increases as you go from the leftmost edge to the rightmost edge, ・0 in this example)
~30) is multiplied and the value of the product is divided by the sum of all values after binarization, that is, the number of phototransistors (17) whose values after smoothing exceed the same value. A central guideline is required.

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" 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.

S (position weight) x (value after binarization) Σ (value after binarization) = 11 Therefore, in the above example, the point where the 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,
In addition to being able to accurately detect the center and position of the guideline,
It is possible to reduce the influence of the appearance of one locally high value that is not eliminated even by the smoothing process described above.

In other words, 1. For example, in FIG. 8, suppose that the smoothed value of the 14th phototransistor (17) other than the guideline position exceeds the same value (1), and even after binarization, the 14th phototransistor (17)
Assuming that "1" is given to phototransistor No. 4, the calculation for calculating the center of the guideline mentioned above is as follows.

(8X1)+(IOXI)+(12X1)+(14X1
)+(26X1)1+1+1+1+1 = 14, and since the detected value [14J, corresponds to the 8th phototransistor position in the sensor (11),
The detected value remains within the width of the guideline (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).

In other words, 1. For example, in the above example, the detected value is "11" and the center position weight of the sensor (11) is "15", so in FIG.
) has shifted to the right, and the steering motor (8) is rotated in a direction that moves 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 process is shown in Figure 10 as a flowchart, and in this execution sequence, from "Start" to "Rotate the steering wheel to the left" or "Rotate the steering wheel to the right" and then again to "Storing the amount of light received...in the memory". It takes about 30 milliseconds for one cycle to return to the original state, and by repeating this process repeatedly while driving, the unmanned vehicle can become dirty on the guideline.

Or, even if there is a problem such as the reflection of the floor differing depending on the location, the vehicle can smoothly follow the guideline.

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.

In any case, as is clear from the above description, the present invention relates to light-receiving elements exceeding the same value for guideline detection in an optical sensor, by adding the weights given with respect to the position of the light-receiving element, By dividing the weight by the number of light-receiving elements exceeding the above-mentioned value, the center position of the guideline relative to the optical sensor is detected and the unmanned vehicle is guided, so the guideline is laid by applying paint to the floor surface. Even if the width of the guideline changes depending on the situation, it is possible to guide the guide very smoothly without meandering or the like.

[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 Figs. 3 and 4 are cross-sectional views taken along the lines AA and B-B in Fig. 2, respectively. , Figure 5 is the circuit diagram, Figure 6 is the circuit diagram.
The figure is a block diagram showing the connection 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, and Figure 8 is a diagram showing the positional relationship between the phototransistor of the optical sensor and the guideline. A bar graph showing the actual value of the amount of light received and the value after smoothing, Fig. 9 is for each phototransistor (1)...Unmanned vehicle, (
2) Drive wheel (5) Steering device, old) Optical sensor (12+)
...Guideline, αD...Phototransistor (c)...Floor surface, (1)...Equivalent value,
(E) - Position weight. Figure 5 7-F Figure 2 Figure 6 Flash Figure 7 Figure 8 Section 9

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,
By adding the weight given to the light receiving element position for the light receiving element that exceeds the threshold for guideline detection in the optical sensor, and dividing the added weight by the number of light receiving elements that exceed the above threshold. A guidance method for an unmanned vehicle characterized by detecting the center of a guideline for an optical sensor.