JPH0435923Y2 - - Google Patents

Description

[Detailed description of the invention] [Industrial application field] The present invention is an optically guided mobile vehicle equipped with a travel control means for automatically traveling a mobile vehicle used for transporting goods, etc. Relating to an optically guided mobile vehicle, comprising: an optical sensor for detecting a line for guiding a mobile vehicle provided along the line; and travel control means for causing the mobile vehicle to travel along the line based on information detected by the optical sensor. .

[Conventional technology]

In this type of optically guided mobile vehicle, lines for guiding the mobile vehicle are arranged to form bifurcated or trifurcated intersections, or lines for guiding the mobile vehicle are arranged between multiple stations. A line for guiding moving vehicles is installed in the vehicle, and travel is controlled based on information detected by an optical sensor that receives light from the line.

By the way, lines for guiding moving vehicles are constructed by pasting light-reflecting tape, or by coating a band of luminescent material such as fluorescent paint that emits light when irradiated with ultraviolet light. in case of,
The light reflected from the light-reflecting tape is detected by an optical sensor, and in the latter case, the light emitted from the luminescent material is detected by an optical sensor.

The conventional structure of the above-mentioned optical sensor will be explained based on FIG. 7, taking as an example a case where a light reflective tape is pasted on the road surface. The light reflecting tape 4 provided on the
The spherical lens Lb is configured to reduce and project the image as an erect image onto the light receiving surface of the light receiving section 6 using an image sensor such as the above.

[Problem that the invention attempts to solve]

In this type of mobile vehicle, various control devices are installed inside the vehicle in order to automatically determine the travel route and operate the vehicle while centrally managing the operation using ground-side equipment, which saves space for installing it. In order to ensure this, it is desired to downsize sensors and the like that detect various information for controlling driving.

However, in the optical sensor having the above-mentioned conventional configuration, a spherical lens was used to condense the light from the line for guiding the moving vehicle to the light receiving part, so the line and the optical sensor were condensed. The optical path length between the optical sensor and the light-receiving surface becomes long, which has the disadvantage that the optical sensor cannot be miniaturized.

Generally, in order to obtain an erect image of an object using a spherical lens, it is necessary to use a combination of multiple spherical lenses, and if the periphery of the lens is used to form an image, Since image distortion increases at the imaging plane, it is difficult to make the optical path length between the object plane and the imaging plane shorter than the focal length, and since the optical path length becomes longer, the imaging Since the amount of light reaching the surface decreases, it is necessary to increase the light-receiving sensitivity of the optical sensor. By the way, the focal length when using a typical spherical lens is around 30cm.

However, if the light-receiving sensitivity of the optical sensor is made too high, it will also receive light incident from the surrounding area of the sensor other than the light from the line for guiding moving vehicles, reducing the accuracy of the line detection information obtained from the optical sensor. This causes the inconvenience that malfunctions are likely to occur.

Also, in order to shorten the optical path length between the object surface and the image forming surface, it is possible to use a spherical lens with a short focal length, such as a wide-angle lens, but in that case, the viewing angle As it gets bigger,
This has disadvantages in that the image at the periphery of the lens becomes blurred, and the difference in the amount of light received between the center and the periphery of the lens becomes large, making it difficult to uniformly detect the periphery of the line.

Further, as shown in FIG. 5, the light reflective tape 4
On the reflective surface of the light reflecting tape 4, markings m ₁ to m indicating stop positions, branching positions, etc. of the traveling route as well as striped patterns formed along the longitudinal direction of the light reflective tape 4 are provided as steering information indicating the traveling route. In some cases, various types of information are displayed using the lines themselves, such as by providing a line _3. In this case, as mentioned above, if the formed image, that is, the amount of light received at the light receiving surface of the photosensor is not homogeneous, or if the image is blurred. , there is a risk that various information that will be formed as such a fine pattern may not be accurately detected.

Therefore, with a configuration in which a spherical lens is used to guide light from a line to an optical sensor, it is difficult to simplify or downsize the optical sensor configuration.

The present invention has been made in view of the above-mentioned circumstances, and its purpose is to miniaturize an optical sensor for detecting a line for guiding moving vehicles without reducing its detection accuracy.

[Means for solving problems]

The characteristic configuration of the optically guided mobile vehicle according to the present invention is as follows:
The optical sensor is configured such that a plurality of graded refractive index lenses are arranged along the width direction of the line to guide light from the line for guiding the moving vehicle to the light receiving part. The actions and effects are as follows.

[Effect]

Generally, when a gradient index lens is used, the distance between the object plane, that is, the line plane, and the image plane, that is, the light-receiving part of the optical sensor, is as shown in the following equation ().
TC is the sum of the length Z ₀ of the lens used and twice its working distance l ₀ . (Refer to Figure 1) TC=Z ₀ +2l ₀ ...() However, l ₀ = -1/n ₀ √Atan (Z ₀ π/P) A: Refractive index distribution constant n ₀ : Refractive index on the optical axis of the lens P: Length of one cycle of light meandering within the lens.

Then, by arranging a plurality of gradient index lenses along the width direction of the line for guiding moving vehicles and guiding the light passing through each lens to the light receiving surface of the optical sensor, the line as a whole can be With a short optical path length, the light can uniformly reach the surrounding area regardless of the size of the light receiving area.

In addition, since the optical path length can be shortened, the optical sensor can be placed close to the line, and since the viewing angle of the gradient index lens itself is relatively narrow, the optical It is possible to prevent the sensor from receiving light from sources other than the line.

〔Effect of the invention〕

Therefore, the light from the line can be guided to the light receiving part with a short optical path length and uniformly to the surrounding area regardless of the size of the light receiving part, which reduces the detection accuracy of the optical sensor. The optical path length between the line and the light-receiving section of the optical sensor can be shortened and the device can be made smaller. Moreover, due to the characteristics of the gradient index lens, it is possible to make it difficult for light other than the line light to enter the light receiving section, and it is possible to create an erect image without using lenses other than the gradient index lens or a reflector. Therefore, from this point of view as well, it is possible to simplify the configuration of the optical system and to significantly reduce the size of the entire optical sensor compared to the conventional one. Overall, while providing an excellent detection surface that is less susceptible to external disturbances, it is possible to reduce the space required to install an optical sensor on a moving vehicle, and to reduce the installation surface when installing an optical sensor on a moving vehicle. and the degree of freedom in terms of placement is increased,
This allows the configuration of the mobile vehicle to be advantageous.

〔Example〕

Hereinafter, embodiments of the present invention will be described based on the drawings.

As shown in FIGS. 3 and 4, a mobile vehicle A is provided with a loading platform 1 that can be driven up and down, and a plurality of load transfer stations ST are located on the lateral side of the traveling path of the mobile vehicle. The mobile vehicle A is provided so as to transport various loads while traveling between the stations.

The mobile vehicle A is configured by providing a pair of left and right propulsion wheels 2 that can be independently driven by a pair of electric motors M, and a pair of left and right caster type idle wheels 3 provided at the front and rear ends of the vehicle body. Then, the electric motors M, M are operated to change their speeds so as to differentiate the rotational speeds of the left and right propulsion wheels 2, 2, thereby steering the vehicle.

As shown in FIGS. 3 to 5, a light-reflecting tape 4 as a line for guiding moving vehicles is provided on the road surface side, and an optical sensor S for detecting the light-reflecting tape 4 is installed on the moving vehicle A side. Travel control means are provided at both front and rear ends of the vehicle body to control the mobile vehicle A to automatically travel along the light reflective tape 4, so that the mobile vehicle A automatically travels between the stations ST. be.

As shown in FIG. 2, there are a light source 5 as an illumination means for illuminating the light reflective tape 4, a light receiver 6 for detecting traveling information using an image sensor, and a light collecting device having a structure to be described in detail later. A light sensor S consisting of a lens L is provided at each of the front and rear ends of the moving vehicle A, and a travel control means is provided for causing the moving vehicle A to travel along the line 4 based on the detection information of the light sensor S. There is. In other words, the travel control device B includes a host controller 7, an image processing controller 8, and a digital servo controller 9.
are provided on the moving vehicle side, and furthermore, both electric motors M
An encoder 10 attached to the motor M is connected to the digital servo controller 9, and the digital servo controller 9 is connected to a servo amplifier 12 for both electric motors M via a servo amplifier driver 11. At step 8, the speeds of both electric motors M are changed so that the amount of lateral deviation of the machine body relative to the light reflecting tape 4 is reduced to zero.

As shown in FIG. 1, the optical sensor S includes a plurality of gradient index lenses L between a light reflecting tape 4 provided on a running road surface and a light receiver 6 of the optical sensor S. A lens array La arranged along the width direction of the reflective tape 4 is provided, and the reflected light from the light reflective tape 4 guided through each gradient index lens L is directed onto the light receiving section 6. The images are formed adjacent to each other, and the light-reflecting tape 4 as a whole can be seen through the light-receiving section 6 through the lens array La as an erect image. In this embodiment, since a two-dimensional image sensor is used as the light receiver 6, the lens array La includes a plurality of gradient index lenses L arranged in the longitudinal direction of the light reflecting tape 4. It has been done.

Incidentally, in this example, the lens length Z ₀ of the gradient index lens L is approximately 30 mm, and its working distance l ₀
is set to approximately 22mm, and the light reflective tape 4
The optical path length between the light receiving surface and the light receiving surface of the light receiving section 6 is approximately 74 mm.

Therefore, since the optical path length becomes very short, the light receiving section 6 and the light reflecting tape 4 can be placed close to each other, making it difficult for light from other than the detection surface of the light reflecting tape 4 to enter the light receiving section 6. , no special shielding member is required. Furthermore, since the optical path length is short, the amount of light reaching the light receiving section 6 is less reduced, and the amount of light from the light source 5 that illuminates the light reflecting tape 4 can also be reduced. As a result, the installation space for the optical sensor S becomes very compact, and the entire optical sensor S can be housed in the lower part of the vehicle body of the mobile vehicle A.

It should be noted that the optical sensor S is configured to selectively use the one on the front side when the vehicle is moving forward, and the one on the rear side when the vehicle is moving backward.

Further, as shown in FIGS. 4 and 5, marks m ₁ and m display travel control information such as the stop position of the moving vehicle A with respect to the station ST, the branch start position at the intersection, and the deceleration start position. ₂ ,
_m3 is attached on the light reflective tape 4, and various control information such as destination data and turning data can be transmitted from the ground side to the moving vehicle side.
In order to transmit various information such as station arrival data and intersection arrival data from the moving vehicle side to the ground side, optical communication devices 13 and 14 are connected to the moving vehicle side as shown in FIGS. 2 and 4. , and are provided at the station section and intersection section on the ground side, respectively. Then, the mobile vehicle side communication device 13 is connected to the host controller 7, and the ground side communication device 14 is connected to the host controller 7.
are connected to a central control device C as ground-side equipment, respectively, so that bidirectional communication is possible between the mobile vehicle A and the central control device C as ground-side equipment, and the central control device C Based on various information such as information input to the station ST and information stored in advance, the mobile vehicle A can automatically travel to a desired station ST while branching at an intersection. In the figure, a indicates a transmitter of the communication devices 13 and 14, and b indicates a receiver.

The optical sensor S detects travel control information by reading marks together with steering control information,
The image processing controller 8 transmits a mark discrimination signal to the host controller 7, the host controller 7 transmits traveling speed information, turning information, forward/backward movement information, etc. to the digital servo controller 9, and the digital servo controller 9 transmits the detection signal to be used. The digital servo controller 9 transmits information on whether the digital servo controller 9 is running or not to the host controller 7.
The travel control of the moving vehicle A is performed while exchanging information between the respective controllers 7, 8, and 9. However, a command information input section for the central control device C is provided at each station ST, and
The mobile vehicle A is equipped with an information input section for the host controller 7.

Hereinafter, the travel control operation will be explained in detail based on the flowchart shown in FIG.

That is, when a driving command such as destination data is transmitted via the communication devices 13 and 14, image capture by the optical sensor S is started, and the steering is performed by measuring the amount of deviation of the light reflective tape 4 from the center. Control is performed, and then mark m ₁ for travel control command
Upon reading ~ _m3 , the vehicle will diverge at the intersection, decelerate near the station ST, and temporarily stop at the station ST.
Incidentally, when starting the image capture, if there is no light reflective tape 4 (including when the travel control command marks m ₁ to m ₃ are absent), an emergency stop is made to increase safety. Yes, and a start command (receiving a power ON signal for moving the mobile vehicle to run, a running command signal via the communication devices 13 and 14, etc.)
Vehicle A will travel only when there is.

[Another example]

The gradient index lens L that guides the light from the line 4 for guiding the moving vehicle to the light receiving section 6 of the optical sensor S is a so-called rod lens, self-ox lens, GRIN lens, etc.
The refractive index distribution constant, lens length, etc. can be set according to the required detection accuracy and installation space.
Alternatively, optical fibers made of glass or plastic formed in the shape of a refractive index distribution and cut into a predetermined length may be used.

Further, as the illumination means 5 for illuminating the light reflecting tape 4, various types such as a fluorescent lamp, an incandescent lamp, a light emitting diode array, etc. can be used.

Moreover, in configuring the light receiving section 6 of the optical sensor S,
In addition to configuring the image sensor using a CCD or the like in a two-dimensional type, various modifications can be made, such as using a one-dimensional type, or using an array of multiple light receiving elements such as photodiodes.

[Brief explanation of the drawing]

The drawings show an embodiment of the optically guided mobile vehicle according to the present invention, FIG. 1 is a diagram showing the configuration of the optical sensor, FIG. 2 is a block diagram showing the configuration of the travel control device, and FIG. 3 is a diagram showing the configuration of the mobile vehicle. FIG. 4 is a plan view showing the layout of the travel route, FIG. 5 is an enlarged plan view showing the structure of the light reflective tape, and FIG. 6 is a flowchart showing the operation of the travel control device. FIG. 7 is a drawing showing a conventional example. A... Mobile vehicle, S... Optical sensor, 4... Light reflective tape, 6... Light receiving section, L... Gradient index lens.

Claims (1)

[Scope of utility model registration request] Travel control means comprising an optical sensor S for detecting a line 4 for guiding a mobile vehicle provided along a travel route, and causing the mobile vehicle A to travel along the line 4 based on information detected by the optical sensor S. In the optically guided mobile vehicle, the optical sensor S includes a plurality of gradient index lenses L that guide the light from the line 4 to the light receiving section 6 in the width direction of the line 4. Optically guided vehicles arranged along the