JPH1165659A - Automatic guided vehicle - Google Patents

Abstract

(57) [Problem] To provide an automatic guided vehicle that can reliably detect both an obstacle and approaching a vehicle body without interference while having an inexpensive configuration using the same propagation medium. A first light projector for emitting light for obstacle detection to a obstacle detection means in a traveling direction side for a first detection time and a light emission timing of the first light projector in synchronization with the first light projector. And a first light receiver 14 for receiving the reflected light from the obstacle 27 of the light emitted from the first light projector 13. The vehicle body approaching detecting means 28 includes a plurality of second projectors 17 that continuously emit light for vehicle body approaching detection toward another automatic guided vehicle traveling on the same transport path, Second floodlight 17
And a plurality of second light receivers 18 for receiving the light emitted from the second light receiver. When the first light receiver 13 continuously receives light for the first time T1, or when the second light receiver 18 continuously receives light for a second time T2 longer than the first time T1, the vehicle body 1 A travel stop control means 19 for temporarily stopping travel is provided.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an automatic guided vehicle used in an automatic guided vehicle system in which a plurality of automatic guided vehicles run on the same transport path set by a guide line. In particular, the present invention relates to an automatic guided vehicle having a function of detecting an obstacle or detecting a risk of collision or collision between the automatic guided vehicles and temporarily stopping the vehicle.

[0002]

2. Description of the Related Art In recent years, in a production plant that operates 24 hours a day, production materials and products are mainly transferred between an unmanned warehouse and a production facility for the purpose of automation and labor saving to reduce the burden on production workers. An unmanned transfer system for transferring by an unmanned transfer vehicle is frequently used. In order to control the traveling of the automatic guided vehicle, a guidance method using a fixed transportation path, which is advantageous in terms of cost and technology, is generally adopted. The automatic guided vehicle is mounted on a floor of a factory or the like by an optical or electromagnetic method. The vehicle automatically travels along the guidance line while detecting the guidance line laid on the surface with the guidance sensor.

[0003] Such an automatic guided vehicle travels on a fixed transport path set by a guide line.
It is necessary to provide an obstacle detection function for detecting an object that may collide in front of the transport path and temporarily stopping traveling when the object is present. Further, in an automatic guided vehicle system in which a plurality of unmanned transport vehicles share the same transport path, in order to prevent unmanned transport vehicles that are traveling at the same time from colliding or colliding with each other, the transport path is particularly limited. It is necessary to have a vehicle body approaching detection function for detecting each other's vehicle bodies in the vicinity of the confluence point to prevent a collision.

[0004] The obstacle detection function provided in the conventional automatic guided vehicle includes (A) means for detecting the obstacle by receiving reflected light of the light projected in the traveling direction from the obstacle,
Alternatively, (B) means for receiving the reflected wave of the ultrasonic wave transmitted in the traveling direction from the obstacle and detecting the obstacle is mainly used. On the other hand, as a vehicle approach detection function,
(C) A traffic signal as a ground communication control device for controlling only one unmanned guided vehicle to enter is installed at the entrance and exit of the intersection of the transport path, and the unmanned guided vehicle communicates with the traffic signal at the entrance and exit of the intersection. Means to control the traveling by going,
(D) A means in which unmanned guided vehicles communicate with each other by transmitting and receiving radio waves near the intersection of the transport path and one of them is temporarily stopped, and (E) a communication means for transmitting and receiving obstacle detection is also used. (G) means for detecting other automatic guided vehicles, (F) means for detecting other automatic guided vehicles by expanding the range of obstacle detection means near the intersection of the transport path, and (G) different from those for detecting obstacles Means for transmitting and receiving the encoded pattern pulse between the automatic guided vehicles are generally used.

[0005]

[Problems to be solved by the invention]
(E), (F), (G) other than the body approach detection function
Since it is used in combination with the obstacle detection function of (A) or (B), it is necessary to use a different communication medium such as using ultrasonic waves for obstacle detection and using light for vehicle approach detection. In this case, the possibility of interference between the obstacle detection and the vehicle body approaching detection function is low, but it is necessary to equip the automatic guided vehicle with a plurality of types of communication media, resulting in a problem of high cost.

In addition, the means (C) requires an installation location of the ground communication control device on the floor or wall near the traveling road, which imposes restrictions on the construction of the traveling road, and also requires an intersection. There is a problem that the installation and control of the terrestrial communication control device are required and the cost increases. In the means of (E), the receiving means for detecting other automatic guided vehicles is generally set to have relatively high sensitivity. When it is received, there is a possibility that it is erroneously detected that it is detection of approach of another automatic guided vehicle. (F)
In the case of the means (E), similarly to the means (E), when there are pillars and wall surfaces near the intersection of the transport path, they are erroneously detected as obstacles. I can not use it. In the means (G), the modulated wave pulses for the obstacle detection and the vehicle body approach detection interfere with each other to become different modulated wave pulses, and there is a possibility that the approach of the obstacle or the vehicle body cannot be reliably detected.

SUMMARY OF THE INVENTION It is an object of the present invention to provide an automatic guided vehicle capable of reliably detecting both an obstacle and approaching a vehicle body without interference while having an inexpensive configuration using the same propagation medium. It is assumed that.

[0008]

SUMMARY OF THE INVENTION In order to achieve the above object, the present invention provides a first light projector for emitting light for detecting an obstacle toward a traveling direction for a first time, and the first light projector. Obstacle detecting means having a first light receiver for receiving reflected light from an obstacle of the light emitted from the first light emitter in synchronization with the light emission timing of the first light emitter, and another unmanned person traveling on the same transport path. A plurality of second light emitters that continuously emit light for detecting the approach of the vehicle toward the carrier, and a plurality of second light receivers that receive light emitted from the second light emitters of the other automatic guided vehicles And the vehicle-body approaching detection means having the following configuration: when the first light receiver continuously receives light for the first time, or when the second light receiver continuously lights for a second time longer than the first time. Running stop control means for temporarily stopping the running of the vehicle body when receiving light.

In the automatic guided vehicle of the present invention, the obstacle is detected by continuously receiving the reflected light of the emitted light from the obstacle for the first time, and the light is emitted from the other automatic guided vehicle. Is continuously received for a second time longer than the first time to detect the approach of another automatic guided vehicle. Therefore, the same propagation medium by light is used for both the detection means for the obstacle and the approach of the vehicle body, so that the configuration is simplified, and even though the cost is reduced, the interference can be detected without fail. .

Further, in the above invention, the first projector and the second projector are configured to project pulsed light of the same frequency, and the first projector has a light intensity smaller than that of the second projector. It is preferable to have a configuration in which a large light is projected.

Thus, since pulsed light having the same frequency is used, there is no adverse effect due to mutual interference of the pulsed light. Further, since the first light emitter is made to be strong light, an obstacle can be reliably detected by reflection, and even if the strong light of the first light emitter is received by the second light receiver, the detection time is different. Erroneous detection.

[0012]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Preferred embodiments of the present invention will be described below with reference to the drawings. FIG. 1 is a schematic side view of an automatic guided vehicle according to the present invention, and FIG. 2 is a block diagram thereof.

In FIG. 1, a vehicle body 1 on which an object to be conveyed is loaded is provided on both rear sides of the vehicle body 1 with driving wheels 2 which are also provided on the front side on a center line along the traveling direction and serve also as steering wheels. It is of a tricycle type that travels with a pair of driven wheels 3,3. The vehicle body 1 travels with the rotation of the drive wheels 2 transmitted through a reduction gear (not shown) through the rotation of the traveling motor 4, and reduces the rotation of the steering motor 7 by a reduction gear (not shown). The traveling direction is controlled by rotating the driving wheel 2 around a horizontal plane by transmitting the driving force via the belt 8.

An inductive sensor 9 is attached to the driving wheel 2 by the mounting member 1.
The guide sensor 9 is attached to the front side in the traveling direction through the center wheel 0 and is rotated around a horizontal plane integrally with the drive wheel 2. The guide sensor 9 includes, for example, a light-emitting element and a light-receiving element. The guide sensor 9 optically detects a guide line 12 that forms a transport path by laying an optical reflection tape or the like on a floor surface 11. A marker provided near each position is optically detected. In addition,
When the guide line 12 is formed by a magnetic tape, a magnetic sensor is used as the guide sensor 9. The steering motor 7 is driven to rotate in accordance with the amount of deviation from the guidance line 12 detected by the guidance sensor 9, whereby the drive wheels 2 are driven.
Is steered so that the center of the guidance sensor 9 is along the center line of the guidance line 12, and the vehicle body 1 travels while being controlled to always follow the guidance line 12.

The vehicle body 1 is provided with a first light projecting device 13 and a first light receiving device 14 for detecting an obstacle on the front side with respect to the traveling direction. There are a total of six sets of second projectors 17 and second light receivers 18 for detecting the approach of another automatic guided vehicle at the front, rear, and front and rear positions with respect to the traveling direction in FIG.
Are arranged. The second light emitting device 17 and the second light receiving device 18 on both sides are installed with their light emitting surfaces and light receiving surfaces facing obliquely front and outside and obliquely rear outside, respectively. Both the first and second light projectors 13 and 17 emit high-frequency modulated pulse light of the same frequency, but the pulse light of the first light projector 13 converts reflected light from an obstacle into first light. Since the light needs to be received by the light receiver 14, the light is set to be stronger than the second projector 17. The light projectors 13 and 17, the light receivers 14 and 18, the traveling motor 4, and the steering motor 7 are controlled by a control device 19 mounted on the vehicle body 1.

In FIG. 2, a traveling distance detecting encoder 20 for detecting the amount of rotation of the traveling motor 4 is provided.
The steering motor 7 is provided with a steering angle detection encoder 21 for detecting the rotation angle of the motor 7, that is, the steering angle of the drive wheel 2. The obstacle detection means 22
The first projector 13 driven by the pulse oscillator 23 emits a predetermined pulse modulated light toward the traveling direction of the vehicle body 1 for a first time, and the reflected light of the light from the obstacle 27 is converted to the first light. The light is received by the light receiver 14 and the received light signal is
4 allows the light to be extracted in synchronization with the light emission timing of the first light projector 13 and input to the control device 19.

On the other hand, each of the six sets of vehicle body approach detection means 28
The second projector 17 driven by the same pulse oscillator 23 continuously emits pulse-modulated light having the same frequency as the first projector 13 in the direction set by the installation direction, and the second The light receiver 18 receives light from the second projector 17 in another automatic guided vehicle and inputs the light to the control device 19.

The central processing unit 29 of the control unit 19 receives a marker detection signal from the induction sensor 9 every time the detection signal is input.
While reading required control data from the RAM 31,
The control program stored in the ROM 30 is executed to control the driving of the obstacle detecting means 22 and the required vehicle approach detecting means 28, and the light receiving signals from the obstacle detecting means 22 and the required vehicle approach detecting means 28 are transmitted by a timer. Based on the count, the presence / absence of an obstacle or the presence or absence of another automatic guided vehicle is determined, and the rotation of the travel motor 4 is controlled based on the determination result to control the travel and stop of the vehicle body. Therefore, the control device 19 also has the function of the traveling stop control means of the vehicle body 1. Next, signal processing for this control will be described with reference to FIGS.

First, an outline of control by the control device 19 will be described with reference to FIG. The central processing unit 29 sets the marker count number M to [1] when the vehicle body 1 starts traveling from the home station serving as the base point of the transport path (step S1), and executes the M-th control program from the ROM 30. The M-th control data is read from the RAM 31 (step S2). And the central processing unit 29
Executes a control program based on the read control data, and executes an obstacle detecting means 22 and a vehicle approach detecting means 2.
8 is turned on or off, and a stop signal output to the traveling motor 4 by discriminating the light receiving signals from both means 22 and 28 is output.
F (step S3).

During this control, it is determined whether or not a marker detection signal has been input from the induction sensor 9 (step S4).
On the other hand, when the marker detection signal is input while the marker detection signal is input, the setting of the marker count number M is incremented by 1 and updated (step S5), and the control corresponding to the set marker count number M is performed. The program and the control data are read out (step S2), and the same signal processing as described above is performed until it is determined that the traveling is completed (step S6). That is, the central processing unit 29 performs various controls by reading out a control program corresponding to each section between the markers on the guide line 12 and executing the control program in the section until the next marker is detected. . In other words, sections in which the same control is continuously performed are classified by setting markers, and a control program and control data for each of the divided sections are stored in the ROM 30 and the RAM 31 in advance.

Next, specific obstacle detection processing and vehicle body approach detection processing in the control of FIG. 3 (step S3) will be described below with reference to FIGS. 4 and 5, respectively.

First, the obstacle detection processing will be described with reference to FIG. The central processing unit 29 executes the read control program and drives or stops driving the first light projector 13 and the first light receiver 14 based on the control data (Step S7). That is, the central processing unit 29
Drives the first light emitter 13 and the first light receiver 14 when the control data is for the detection valid section in the guide line 12, and on the other hand, when the control data is for the detection invalid section, Stop driving. Here, the detection invalid section is, for example, a section such as a corner section near a wall that may erroneously detect an obstacle that does not disturb the traveling such as a wall surface or a pillar as an obstacle, and other sections are valid for detection. The section is set in the control data.

If it is a detection effective section, the first light emitter 13 is driven to emit light by the pulse oscillator 23 to emit a modulated pulse light of a predetermined frequency forward in the traveling direction for a first time T1. Then, it is determined whether or not light is received by the first light receiver 14 (step S8). The first time T1 is set to, for example, 200 msec. Here, if the first light receiver 14 does not receive the reflected light due to the absence of the obstacle 27 in front of the traveling direction of the vehicle body 1, the count number C is set.

[0] (step S13), and the stop signal to the traveling motor 4 is set to O.
FF is performed (step S14).

On the other hand, when it is determined that the first light receiver 14 has received light (step S8), the count C is incremented by one and updated (step S9).
An interrupt process is performed by the timer 32 to determine whether or not the count number C is equal to or greater than [20] (step S1).
0). The reason for determining whether or not the count number C is equal to or more than [20] is that the first time T1 is set to 200 msec as described above in this embodiment, and the interrupt processing by the timer 32 is performed. Is performed every 10 msec.

If the count number C is less than [20], the stop signal is kept OFF (step S1).
4) Go to step S12. When the count number C is [2
0] or more, it is determined that some obstacle is present ahead of the traveling direction, and the stop signal is turned on to stop the traveling motor 4 while decelerating (step S).
11). These processes are continued until it is determined that the execution of the read control program has been completed (step S12). Here, the ON state of the stop signal also includes a case where the vehicle approaches the unmanned transport vehicle in front when the driving of the vehicle body approach detection means 28 is stopped, and accordingly, the unmanned transport vehicle in front is turned on. A rear-end collision can be prevented.

As described above, in this embodiment, the first
Is driven for light emission only for a first time T1 set to 200 msec, and the synchronization circuit 24
The light reception signal of the first light receiver 14 is input to the central processing unit 29 in synchronization with the light emission timing of No. 3. Interrupt processing by the timer 32 in the central processing unit 29 is 10 ms.
The stop signal is turned on at the time when it is determined that the first light receiver 14 is continuously receiving light in the 20th interrupt processing, and the interrupt processing is performed 20 times. If it is determined that the first photodetector 14 has not received light before reaching, the count C

It is set to [0] (step S13), and the counting is restarted from the beginning. Therefore, any disturbance light or the like may cause the first light receiver 1
Even if the light beam 4 is instantaneously incident, the probability of erroneously detecting the obstacle 27 is extremely low. In the detection effective section, the driving of the first light emitter 13 and the light receiver 14 is performed intermittently within the first time T1, but the interval does not need to be set to be particularly constant.

Next, the vehicle body approach detection processing will be described with reference to FIG. The central processing unit 29 executes the read control program, and executes a predetermined second process corresponding to the detection valid section set in the read control data.
Is selected and driven (step S15). Here, the vehicle body approach detecting means 2
The detection effective section 8 is set to a section such as a junction, an approach point, or an intersection with another automatic guided vehicle, and in this detection effective section, it is opposed to a section to be detected in another guide line 12. The second light projector 17 and the second light receiver 18 are driven. Separately, the second light receiver 18 on the front side in the traveling direction and the second light receiver 18 on the rear side in the traveling direction
Is always driven. Accordingly, for example, when the driving of the obstacle detection unit 22 is stopped and the vehicle travels in the corner section near the wall, the light emitted from the second projector 17 of the automatic guided vehicle traveling in front of the guide line 12 is rearward. The second receiver 18 of the unmanned guided vehicle on the side receives the light, stops the traveling of the unmanned guided vehicle on the rear side, and prevents the unmanned guided vehicle traveling from the rear side from colliding with the unmanned guided vehicle on the front side. To prevent.

The central processing unit 29 drives the above-mentioned predetermined light projector 17 to emit light by the pulse oscillator 23 to emit a modulated pulse light having the same frequency as that of the first light projector 13, and also outputs the predetermined second light. After the light receiver 18 is set to a driving state capable of receiving light, it is determined whether or not the second light receiver 18 in the driven state has received light (step S16). By performing the processing, the count number C is incremented by 1 and updated (step S17), and it is determined whether or not the count number C is equal to or greater than [40] (step S18). Therefore,
The second time T2 for vehicle body approach detection is a first time T
1 is set to 400 msec longer than 200 msec. If the count number C is less than [40], the stop signal is set to 0FF (step S22), the same processing as described above is continued, and when it is determined that the count number C has reached [40], the stop is performed. The signal is turned on to stop the vehicle body 1 (step S19).

In the case where the control data is the detection valid section of the junction or intersection, if it is determined that the second light receiver 18 in the driven state does not receive light (step S16), the junction or intersection is determined. Assuming that there is no unmanned guided vehicle to the point, count C

After setting to [0] (Step S21), the stop signal is kept OFF (Step S22), and the vehicle continues traveling toward the junction. That is, since the second light receiver 18 facing the other guide line 12 entering the junction does not receive the light, the priority of entry into the junction is secured, and traveling is continued. , The light emission from the predetermined second light projector 17 is continued to the subsequent automatic guided vehicle entering the junction from the guide line 12, and the automatic guided vehicle is stopped.

On the other hand, when the control data is a detection effective section of a junction or an intersection, the second light receiver 1
8 is determined to have received light (step S16),
Assuming that there is an unmanned guided vehicle heading to the junction from another guidance line, the count C is set to 1 by interrupt processing.
The stop signal is turned on (step S1) when it is determined that the count number C has reached [40] or more (step S18).
9) Stop the vehicle body 1. The above-described processing is continued until it is determined that the execution of the read control program has been completed (step S20).

FIG. 6 shows a timing chart in the above processing. In the section D1, another automatic guided vehicle traveling on another guide line 12 approaching without crossing and approaching another obliquely forward. In this state, the case where the second light receiver 18 facing the other automatic guided vehicle is driven is shown. In this case, as shown in FIG. 5D, the strong light of the first projector 13 of the other automatic guided vehicle is received by the second light receiver 18 of the own vehicle, but as shown in FIG. Further, since the count number C by the interrupt processing does not reach [40], the stop signal is not turned on as shown in FIG. On the other hand, as shown in FIG.
Although the light is emitted from the first light projector 13 of the own vehicle, the first light emitter 13 of the own vehicle does not have an obstacle in the forward direction.
No light is received as indicated by the two-dot chain line in FIG. Therefore, there is no erroneous detection that the stop signal is turned ON even though there is no unmanned guided vehicle or obstacle 27 that may collide.

That is, since the obstacle 27 is detected at the first time T1 and the approach of the vehicle body 1 is detected at the second time T2, the first and second projectors 13 and 17 have the same frequency. There is no interference even though the modulated pulse light is projected. Further, by using the same communication medium using the modulated pulse light of the same frequency, the cost is not increased due to the simplification of the configuration, and the adverse effect due to the interference of the pulse light does not occur. The section D2 in FIG. 6 shows the case where the obstacle detection means 22 detects an obstacle and stops, and the section D3 shows the case where the vehicle approach detection means 28 detects the approach of another automatic guided vehicle. This shows a case where the operation has stopped.

[0033]

According to the automatic guided vehicle of the first aspect, the obstacle is detected by continuously receiving the reflected light of the emitted light from the obstacle for the first time, and the other unmanned reflection is performed. Since the approach of another automatic guided vehicle is detected by continuously receiving the light emitted from the vehicle for a second time longer than the first time, both the detection of the obstacle and the approach of the vehicle body are detected. By using the same propagation medium of light as the means, the configuration is simplified, and despite the reduction in cost, no interference occurs, and each of them can be reliably detected.

According to the automatic guided vehicle of the second aspect, the use of pulsed light of the same frequency can prevent adverse effects due to mutual interference of pulsed light, and the projector for detecting obstacles uses strong light. An object can be reliably detected. In addition, even if the strong light is received by the light receiving device for detecting the approach of the vehicle body, erroneous detection is not performed because the detection time is different.

[Brief description of the drawings]

FIG. 1 is a schematic side view of an automatic guided vehicle according to an embodiment of the present invention.

FIG. 2 is a block diagram of the automatic guided vehicle.

FIG. 3 is a flowchart showing a schematic process of controlling the automatic guided vehicle according to the first embodiment;

FIG. 4 is a flowchart showing an obstacle detection process in the above process.

FIG. 5 is a flowchart showing a vehicle-body approach detection process in the above process.

FIG. 6 is a timing chart in the same processing.

[Explanation of symbols]

 DESCRIPTION OF REFERENCE NUMERALS 1 vehicle body 13 first light emitter 14 first light receiver 17 second light emitter 18 second light receiver 19 control device (travel stop control means) 22 obstacle detection means 24 synchronization circuit 27 obstacle 28 obstacle detection means 29 Central processing unit T1 First time T2 Second time

Claims (2)

[Claims] 1. A first projector for projecting light for obstacle detection toward a traveling direction for a first time, and a projection of the first projector in synchronization with a projection timing of the first projector. Obstacle detection means having a first light receiver for receiving reflected light from the obstacle, and continuously projecting light for vehicle body approach detection toward another unmanned guided vehicle traveling on the same transport path. A vehicle body approach detection unit having a plurality of second light emitters that emit light, and a plurality of second light receivers that receive light emitted from the second light emitters of the other automatic guided vehicles; Travel stop control means for temporarily stopping travel of the vehicle body when receiving light continuously for the first time or when the second light receiver continuously receives light for a second time longer than the first time An automatic guided vehicle characterized by comprising: 2. The first projector and the second projector are configured to emit pulsed light having the same frequency, and the first projector emits light having a larger light amount than the second projector. The automatic guided vehicle according to claim 1, wherein the automatic guided vehicle is adapted to emit light.