JPH02171804A - Optical guiding method for unmanned carrier - Google Patents

Abstract

PURPOSE:To stably execute the steering of an unmanned carrier without being affected by the brightness of a floor surface by maintaining the output difference of both light receiving devices constant even when the brightness of the floor surface is changed. CONSTITUTION:When the floor surface area is made bright and the output of a third photodetector 13 is made large, the output of the photodetector 13 is inputted to the positive side of an operational amplifier 21 and the output from the operational amplifier 21 is increased. Then, the input of an operational amplifier 22 is also increased. Since the output of this amplifier 21 is inputted to the negative side of the amplifier 22, the output of the amplifier 22 is decreased and the emitted light quantity of a light emitting element 14 is decreased. Since the output of the amplifier 22 is delayed by resistance R8.C2 and fed back to the negative side input edge of the amplifier 21, the output of the amplifier 21 is increased. As a result, the output of the amplifier 22 is decreased and after repetition, the output of the amplifier 22 is fixed to a decreased voltage. Then, the output of the element 14 is also maintained to a voltage, which is lower than the original standard voltage, and the displacement outputs of photodetecting elements 11 and 12 are controlled constant.

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention is based on the difference between the light receiving elements of two light receiving elements arranged so that the floor surface and the guide tape arranged on the surface can be simultaneously captured within the field of view. The present invention relates to an optical guidance method for an automatic guided vehicle in which a displacement signal of the automatic guided vehicle with respect to a guide tape is obtained.

(Prior art) - When an automatic guided vehicle is run following a guide tape placed on the floor surface, the automatic guided vehicle is set so that the floor surface and the guide tape are simultaneously within the field of view in accordance with the width of the guide tape. Two light-receiving elements that can capture the image are installed, and a displacement signal of the automatic guided vehicle with respect to the guide tape is obtained based on the difference between the two light-receiving elements. In the method of optically guiding the guide tape, it is desirable that the reflectance of the floor surface and guide tape be constant regardless of the location.

However, it is unavoidable that the reflectance of the floor surface changes due to reasons such as abrasion of the floor surface, dirt, or even a difference in the color of the floor.

As a countermeasure to this problem, an unmanned I-room shuttle vehicle as shown in FIG. 6 has been proposed. FIG. 6 is a schematic plan view showing a part of the automatic guided vehicle, in which 1 indicates the automated guided vehicle and 2 indicates a guide tape. A detection board 5 is installed at one end of the unmanned III vehicle transport 1 in the traveling direction, and a first... Second light receiving element 11.12
In addition, a third light receiving element 13 is provided which prevents the guide tape 2 from entering the field of view, in other words, captures only the floor surface within the field of view. Depending on the light receiver of this third light receiving element 13, as shown in FIG. Second light receiving element 11.12
Is there a so-called constant force control for the floor surface that controls the output of the ? 111 law has been proposed and implemented.

Figure 7 is 1. It is a graph showing the relationship between the output of the second light receiving element 11.12 and the brightness of the floor surface.
The positional deviation of the automatic guided vehicle 1 is large, and the field of view of the first light receiving element 11 is occupied by the floor,
shows the output of each light receiving element 11, 12 when the brightness of the floor surface changes when the center of field of view is located on the center of the width of the guide tape 2 (see FIG. 1 (b)).

0 in the graph. ■ is when the brightness of the floor surface is simply changed, and O■ is when the floor power is controlled to be constant. The output of the second light receiving element 11.12 is shown. As is clear from this graph, even if the brightness of the floor changes, the output of the first light receiving element 11 remains constant, and the output of the second light receiving element 12 decreases as the brightness of the floor increases. controlled by.

[Problem to be solved by the invention]

However, in this conventional method, when a phenomenon similar to a change in the brightness of the floor surface due to a change in the height of the detection panel due to a shift in the loaded cargo occurs, the transport vehicle is There was a problem that the running became unstable.

For example, if the height of the detection panel from the floor becomes lower, the first
．． As the floor surface becomes brighter, the output of the light receivers of the second light receiving elements 11 and 12 increases, the displacement signal becomes larger, and the drive motor control gain becomes larger, causing the automatic guided vehicle to run a little hunting. .

Conversely, when the height from the floor increases or when the floor surface becomes dark, the displacement signal becomes smaller, the drive motor control gain becomes smaller, and the movement of the automatic guided vehicle fluctuates greatly at low cycles. A tendency arises.

The present invention has been made in view of the above circumstances, and its purpose is to achieve the following: regardless of changes in the brightness of the floor surface. An object of the present invention is to provide an optical guidance method for an automatic guided vehicle, which enables stable guidance by adjusting the amount of light emitted from a light source so that the difference between the light receivers in a second light receiver becomes constant.

[Means to solve the problem]

The optical guidance method for an unmanned (general transportation vehicle) according to the present invention constantly detects only the reflected light from the floor surface with a third light receiver, and outputs from the first and second light receivers according to the detected value. The amount of light emitted by the light source is controlled to increase or decrease so that the difference between the two levels remains constant regardless of changes in the brightness of the floor.

1 Effect] According to the present invention, the first effect can be detected even by a change in the height of the detection panel with respect to the floor surface or a change in the brightness of the floor surface itself. The difference between the outputs of the second receiver is constant, in other words, the difference between the outputs of the first and second receivers is constant. The light emission amount of the light source is controlled so that the difference in the output of the second light receiver is not affected by the brightness of the floor surface.

〔principle〕

In the optical guidance method according to the present invention, the guide tape 2 is used to detect the displacement of the automatic guided vehicle 1 with respect to the guide tape.
．． The first one was set so that it could capture the floor surface at the same time. Regarding the second light receiving element 1L12, even if the brightness of the floor surface changes, the output difference between the light receiving elements 11 and 12 is maintained constant. 1st. The amount of light emitted from the guide tape 2 and the light emitting element 14 provided for illuminating the floor surface is controlled so that the output difference between the second light receiving elements 11 and 12 changes.

A concrete example of this is as shown in Parts 1 and 2. To simplify the explanation, cases ①, ②, and ② will be explained separately.

■The automatic guided vehicle 1 travels along the guide tape 2 without any positional deviation, and as shown in FIG. In the case where (1) the automatic guided vehicle (1) travels with a large positional deviation relative to the guide tape (2), the field of view of the first light-receiving element (11) as shown in FIG. If the inside is occupied by the floor surface and the center of the field of view of the second light-receiving element is located on the center of the width of the guide tape 2, then the automatic guided vehicle 1 will be positioned in the direction shown in Fig. 1 (a) with respect to the guide tape 2. The vehicle travels in a state where the position is generally shifted to one side by X from the position shown, and the first light receiving element 1 is moved as shown in FIG.
1. When the area ratio between the guide tape 2 and the floor surface within the field of view of the second light receiving element 12 is different, the brightness of the floor surface is changed. The amount of light emitted by the light emitting element is controlled so that the output of the second light receiving element 11.42 becomes as shown in FIG.

In Fig. 2, the vertical axis indicates the first. The output of the second light-receiving element is shown with the brightness of the floor surface on the horizontal axis, and e and h in the graph are shown.
, g of the first light receiving element 11, and f.

12g indicates each output of the second light receiving element 12.

That is, during normal driving (■), the first. Second light receiving element 11.
The outputs of No. 12 match, and when the positional deviation is large as shown in ■, the outputs of No. 1. The outputs of the second light-receiving elements 11 and 12 maintain a predetermined output difference ΔP regardless of changes in the brightness of the floor surface, and furthermore, in the case of ■, the outputs of the second light-receiving elements 11 and 12 maintain a predetermined output difference ΔP regardless of changes in the brightness of the floor surface. The light emission amount of the light emitting element 14 is controlled so that the output of the second light receiving element 11 and 12 remains at an output difference ΔP corresponding to the positional deviation dimension X, regardless of changes in the brightness of the floor surface. .

As a result, changes in the brightness of the floor surface will not have any effect on the steering control of the automatic guided vehicle, allowing accurate and stable travel.

Next, a specific configuration for implementing the method of the present invention will be explained.

〔Example〕

DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be specifically described below based on drawings showing embodiments thereof.

FIG. 3 is a schematic plan view showing the implementation state of the method of the present invention, where l indicates an automatic guided vehicle and 2 indicates a guide tape.

Automated guided vehicle l is in the center of the front and rear directions, and is on the left.

A pair of drive wheels 31 on both right sides! , 3r, and idler wheels 4 are provided at each of the four corners, and a detection board 5 is provided at one end in the running direction. The detection board 5 has two first . A third light-receiving element 13 is located closer to the width direction of the automatic guided vehicle l so that the guide beam 12 does not enter the field of view of the second light-receiving element 11 and 12, and receives only reflected light from the floor surface.
It is equipped with

Note that a large number of light emitting elements 14) composed of light emitting diodes and the like are provided on the lower surface of the detection board 5.

FIG. 4 is a diagram of a light emitting element control circuit used in the method of the present invention, and the output terminal of the third light receiving element 13 in FIG. It is connected to the reference power supply (-Vo), and voltage dividing resistors R,,R,
The midpoint of the signal is connected to the - input terminal (+ side) of the operational amplifier 21. The other input terminal (- side) of the operational amplifier 21 has resistors R8+R9 connected in series interposed therebetween, and
It is connected to the output end of the operational amplifier 22 while being connected to the midpoint between the resistors R1 and 1?3. The midpoint between the resistors R1l and R9 is grounded via a capacitor C2, and a time constant circuit is configured by the resistor Re and the capacitor C2, and the output of the operational amplifier 22 is connected to the time constant R, -C,
The operational amplifier 21 is returned to the human power@(-example) after a delay of 1 minute to stabilize the running time.

The output terminal of the operational amplifier 21 is a resistor R connected in series with each other.
The resistors RIR are connected to the floor force setting power source (voltage -Vs) through 1R
, I, and is connected to the - input end (- side) of the operational amplifier 22 at the midpoint between the resistors R6 and P. The other power end (+ side) of the operational amplifier 22 is grounded. The output end of the operational amplifier 22 is connected to the light emission amount control circuit 23, and the operational amplifier 2
It is connected to the negative input terminal (- example) of the operational amplifier 21, and further connected to the other input terminal (- side) of the operational amplifier 21 via the series-connected resistors R8+Rq as described above.

The light emission amount control circuit 23 is connected to each light emitting element 14 connected in series, and controls the amount of light emission by adjusting the current to these light emitting elements 14.

Now, if the floor surface becomes brighter and the output of the third light-receiving element 13 increases, the output of the light-receiving element 13 is input to the + side of the operational amplifier 21, so the output from the operational amplifier 21 increases, Operational amplifier 220 manpower also increases.

Since the output of the operational amplifier 21 is inputted to one side of the operational amplifier 22, the output of the operational amplifier 22 decreases, the control signal for the light emitting element 14 by the light emission amount control circuit 23 decreases, and the amount of light emitted from the light emitting element 14 decreases. It happens.

In addition, the output of the operational amplifier 22 is delayed by a resistor Rs·02 and is fed back to the input terminal of the operational amplifier 21.
The output of the operational amplifier 21 is further increased. As a result, the output to the input terminal of the operational amplifier 22 is increased, and as a result, the output of the operational amplifier 22 is further decreased.By repeating this process, the output of the operational amplifier 22 settles to a reduced voltage, and therefore, the output of the operational amplifier 22 is reduced to a reduced voltage. The amount of light emitted is also maintained at a reduced value, the output of the light emitting element 14 is maintained at a voltage lower than the initially set standard voltage, and both light receiving elements 11 and 12
The displacement output of is controlled to be constant.

FIG. 5 is a block diagram showing the control system of the method of the present invention, in which the output of the third light receiving element 13 is added to the feed bank amount after passing through a transfer element such as an amplifier (transfer function KO), and The output is subtracted from the floor setting output through a transfer element such as an amplifier (transfer function 2), and output to the light emission control circuit 23 via a transfer element such as an amplifier (transfer function Ks), (4) is fed back to the transfer function, and the above-mentioned cycle is reversed by 1v.

In addition, although the above-mentioned example explained the case where black tape (tape with low reflectance) was used as a guide tape, it is not limited to this in any way, and for example, white tape,
A guide tape with high reflectivity such as a metal tape may be used.

In this case, when the floor surface becomes brighter, the amount of light emitted from the light emitting element 14 is controlled to increase, and similarly, both light receiving element openings and
12 displacement ratio constant control will be performed.

Note that in the above description, the light emitting element 14 and the light receiving element 11
, 12.13 has been described, but the present invention is not limited to this in any way, and it goes without saying that conventionally known light sources, optical sensors, etc. may be used.

〔effect〕

As described above, in the method of the present invention, even if the brightness of the floor surface changes, the output difference between the two light receivers can be maintained constant regardless of the change in the brightness of the floor surface. The present invention has excellent effects, such as being able to stably steer the automatic guided vehicle without being affected.

[Brief explanation of the drawing]

Figures 1 (a), (b), and (c) are explanatory diagrams showing the principle of the method of the present invention, Figure 2 is a graph showing the principle of the method of the present invention, and Figure 3 shows the state of implementation of the method of the present invention. Schematic plan view, 4th
The figure is a light emitting element control circuit diagram, Figure 5 is a block diagram of the control system, Figure 6 is a schematic plan view showing the arrangement of light receiving elements in an automatic guided vehicle, and Figure 7 is a graph showing the principle of the conventional method. It is. 1...Automated guided vehicle 2...Guide tape 11...
-First light receiving element 12...Second light receiving element 13.
...Third light receiving element 14...Light emitting element 2L22.
...Operational amplifier 23...When used as a light-emitting control circuit Applicant Tsubakimoto Chain Co., Ltd. Agent
Patent Attorney Noboru Kono Zushimura

Claims (1)

[Scope of Claims] 1. A light reflection band formed on the floor surface and a light source that illuminates the floor surface on both sides thereof, and a pair of left and right first lights that capture the light reflected from the light reflection band and the floor surface. , a second light receiver, and a first light receiver.
, in a method of optically guiding an automatic guided vehicle following the light reflection zone by a difference in the light receivers of the second light receiver, a third light receiver is provided to capture only the reflected light from the floor surface, and the detection thereof is performed. The amount of light emitted from the light source is controlled to increase or decrease according to the value so that the difference between the outputs of the first and second light receivers remains constant regardless of changes in the brightness of the floor surface. Optical guidance method.