JPH04213705A - Safety device for unmanned carrier - Google Patents

Abstract

PURPOSE:To always execute the detection of an obstacle by one of two kinds of sensors, and to prevent in advance the unmanned car from coming into contact with the obstacle. CONSTITUTION:An unmanned forklift 4 is provided with an ultrasonic sensor 11 for detecting whether an obstacle exists or not by utilizing a reflected wave from the obstacle, and plural photoelectric type sensors 13 of a light emitting/ receiving type. In a warehousing/delivery base 2, a reflecting plate 16 is fixed in a position opposed to the photoelectric type sensor 13. In the case the unmanned forklift 4 approaches toward the warehousing/delivery base 2, a detecting function of the ultrasonic sensor 11 is invalidated in a detection area of the photoelectric type sensor 13 due to an action of a CPU 22, and the obstacle is detected by the photoelectric type sensor 13. In the case of the outside of the detection area of the photoelectric type sensor 13, the detecting function of the ultrasonic sensor 11 becomes effective, and the obstacle is detected by the ultrasonic sensor 11.

Description

[Detailed description of the invention]

0001

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a safety device for an unmanned vehicle that transports cargo between a plurality of stations provided at predetermined locations.

0002

2. Description of the Related Art Unmanned vehicles such as unmanned forklifts are used to transport cargo stored at a predetermined location in a warehouse, factory, or outdoors to another storage location or temporary storage location. Generally, unmanned vehicles travel along guide lines installed between multiple baggage storage locations (stations). Further, as shown in FIG. 7, the unmanned vehicle (unmanned forklift) 30 is equipped with an ultrasonic sensor 31 that detects an obstacle in front of it in the direction of travel, and when the ultrasonic sensor 31 detects an obstacle while driving, a detection signal is emitted. Based on this, the operation of the unmanned vehicle 30 is stopped. However, if the ultrasonic sensor 31 acts when the unmanned forklift 30 approaches the station S and performs cargo handling work, the station S that has entered the detection area of the ultrasonic sensor 31 (shown by the chain line in FIG. 7) becomes an obstacle. It was determined that unmanned forklift 3
0 will be stopped, making it impossible to work. Therefore, conventionally, when the unmanned forklift 30 approaches the station S and performs cargo handling work, the obstacle detection function of the ultrasonic sensor 31 is disabled. Note that the unmanned forklift 30 reaches the station S when a mark plate detection sensor (none of which is shown) installed on the unmanned forklift 30 detects a mark plate placed at a predetermined position along the guide line. It has been confirmed by.

[0003] In addition to the ultrasonic sensor, it is also equipped with a bumper-type sensor, and when the unmanned vehicle moves between stations, the ultrasonic sensor detects obstacles, and the detection function of the ultrasonic sensor is disabled. An unmanned vehicle has also been proposed that uses a bumper-type sensor to detect obstacles when driving in a closed state (Japanese Patent Laid-Open No. 2-235113). or,
Japanese Utility Model Publication No. 2-40001 discloses that, as a device for preventing interference between a stacker crane and a transport vehicle in an automated warehouse, a light beam is emitted in the direction in which the transport vehicle approaches a loading/unloading station, and a fork of the stacker crane is installed at the loading/unloading station. A light projector is provided at a position where the fork blocks the light beam when the fork enters, a light receiver is provided on the transport vehicle at a position where it can receive the light beam, and the light receiver is installed at a position where the transport vehicle approaches the loading/unloading station. A device is disclosed that is provided with a determination unit that prohibits the entry of a transport vehicle when the light beam cannot be received.

0004

[Problems to be Solved by the Invention] In the conventional device, the detection function of the ultrasonic sensor 31 is disabled when approaching the station and during loading/unloading work, so the unmanned forklift 30 cannot detect obstacles in front of it. There is a risk of contact with obstacles. On the other hand, even unmanned vehicles equipped with bumper-type sensors in addition to ultrasonic sensors may not be able to detect obstacles depending on their location (for example, if the obstacle is the left and right guide rails that guide the mast carriage of a reach-type forklift). ). Furthermore, in order to avoid impact when the bumper comes into contact with an obstacle, the unmanned vehicle needs to travel at a considerably low speed, and when applied to an unmanned forklift, there is also the problem that work efficiency decreases.

[0005]Also, although the device disclosed in Japanese Utility Model Publication No. 2-40001 can prevent interference between the transport vehicle and the stacker crane at the loading/unloading station, it is difficult to detect obstacles while the transport vehicle is moving to another station. is not taken into account. In order to use a light receiver provided on a transport vehicle (unmanned vehicle) to detect obstacles on the travel path of the transport vehicle, there is a problem in that a large number of light projectors are required on the travel path of the transport vehicle.

The present invention has been made in view of the above-mentioned problems, and its purpose is to prevent unmanned vehicles from interacting with stations when traveling between stations, when approaching stations, and during loading and unloading operations. An object of the present invention is to provide a safety device for an unmanned vehicle that can reliably detect obstacles existing between the vehicles.

[0007]

[Means for Solving the Problems] In order to achieve the above object, the present invention provides an unmanned vehicle that transports cargo between a plurality of stations provided at predetermined locations. A first sensor (for example, an ultrasonic sensor) that detects the presence or absence of an obstacle using reflected waves from the obstacle, and a plurality of sensors provided in the direction of movement of the unmanned vehicle when the unmanned vehicle approaches each station. a photoelectric type (light emitting/receiving type or light receiving type) second sensor; a light transmitting member that is provided at a predetermined position of each station facing the unmanned vehicle and sends light toward the second sensor; The sensor is equipped with a switching means for switching the operation timing of the second sensor and the second sensor.

[0008]

[Operation] When an unmanned vehicle moves between stations, the first
The first sensor is kept in an operable state, and if there is an obstacle on the path of the unmanned vehicle, the first sensor detects it and the unmanned vehicle is stopped by the detection signal. When the unmanned vehicle approaches the station to load and unload cargo, the detection function of the first sensor is disabled by the action of the switching means. Then, the second sensor detects the presence or absence of an obstacle between the unmanned vehicle and the station. Second
The sensor receives light emitted by itself and reflected by a light transmitting member provided at the station, or light emitted from the light transmitting member. If an obstacle exists between the unmanned vehicle and the station, the light is blocked, the presence of the obstacle is detected by the second sensor, and the unmanned vehicle is stopped based on the detection signal.

[0009]

Embodiments (Embodiment 1) A first embodiment of the present invention in which the present invention is embodied in a reach-type unmanned forklift will be described below with reference to FIGS. 1 to 5. As shown in Figure 3, baggage storage area 1 as a station
A guide line 3 through which a guide signal flows is laid between the storage area and the loading/unloading platform 2, and a travel path for the unmanned forklift 4 is set. The unmanned forklift 4 moves along the travel path by detecting the guide wire 3 with a pair of left and right travel pickup coils (not shown) installed on the bottom of the rear side (on the side opposite to the side where the fork 5 is attached). It looks like this. Mark plates 6 and 7 are fixed at predetermined positions in front of the storage area 1 and the loading/unloading table 2, and another mark plate 8 is fixedly arranged at a predetermined position away from the mark plates 6 and 7 along the travel path. ing. Each mark plate 6-8
are arranged in two rows in a direction perpendicular to the guide line 3 (however, the number of mark plates or the combination of arrangement differs).

As shown in FIGS. 1 and 2, above both front wheels 10 on the front side (the side where the fork 5 and mast 9 are attached) of the unmanned forklift 4, there is a system that uses reflected waves from obstacles to detect the presence or absence of obstacles. A pair of ultrasonic sensors 11 are disposed as first sensors for detection, and one ultrasonic sensor 12 is disposed at the center of the rear side of the unmanned forklift 4. Further, on the front side of the unmanned forklift 4, a plurality (five in this embodiment) of light emitting/receiving type photoelectric sensors 13 as second sensors are provided at equal intervals in the width direction of the unmanned forklift 4. Two of the five photoelectric sensors 13 are disposed outside the ultrasonic sensor 11, and three of the five photoelectric sensors 13 are provided on support bars installed inside the tip of a guide rail 14 that guides a mast carriage (not shown). It is arranged on 15. In the storage area 1 and loading/unloading platform 2 facing the unmanned forklift 4 when the unmanned forklift 4 moves forward, there is a light transmitting member that sends light toward the photoelectric sensor 13 at a position facing each of the photoelectric sensors 13. Reflective plates 16 are each fixed. The detection range of the ultrasonic sensors 11 and 12 is divided into two stages as shown in FIGS. 4 and 5, and the detection range of the first area A1 is approximately within 2 m,
The detection range of the second area A2 is within approximately 1 m. On the other hand, each of the photoelectric sensors 13 is irradiated by the photoelectric sensor 13 at a distance of approximately 1 m from the reflector 16 and is slightly larger than the second area A2 of the ultrasonic sensor 11, and the reflector It is possible to reliably receive a predetermined amount of light reflected by 16. The lowest height of the lifting range of the fork 5 is such that the fork does not interfere with the photoelectric sensor 13 disposed on the support bar 15 when the fork is placed at the position.

As shown in FIGS. 1 and 2, two sets of mark plate detection sensors 17 are provided at the bottom of the unmanned forklift 4 to detect each of the mark plates 6 to 8. A microcomputer 18, a travel controller 19, and a travel pulse output device 2 are installed at the rear of the unmanned forklift 4.
0 is set. The driving controller 19 is the driving wheel 2
A driving motor (not shown) that drives the motor 1 is controlled based on instructions from a microcomputer 18.

The microcomputer 18 includes a central processing unit (CPU) 22 as a switching means for switching the operating timing of the ultrasonic sensor 11 and the photoelectric sensor 13, an interface 23, and a program memory 24 consisting of a read-only memory (ROM). and a working memory 25 consisting of a readable and rewritable memory (RAM). The CPU 22 operates based on a control program stored in the program memory 24. The program memory 24 stores in advance data of operation instruction contents for the arrangement patterns of each of the mark plates 6 to 8. Further, detection signals from the ultrasonic sensors 11 and 12, the photoelectric sensor 13, and the mark plate detection sensor 17, and an output signal from the travel pulse output device 20 are input to the CPU 22 via an interface 23. ing. And CPU22
If it is determined that an obstacle exists in the first area A1 based on the detection signals of the ultrasonic sensors 11 and 12, it sends a command signal to the travel controller 19 to cause the unmanned forklift 4 to travel at a predetermined low speed. Further, if it is determined that an obstacle exists in the second area A2, a stop command signal is sent to the travel controller 19.

Next, the operation of the apparatus constructed as described above will be explained. When the unmanned forklift 4 normally travels, it moves backwards, that is, with the side opposite to the forks 5 facing forward. In this state, the ultrasonic sensor 12 disposed on the rear side of the unmanned forklift 4 is maintained in an operating state, and obstacles on the travel path are detected. When the unmanned forklift 4 continues to travel along the travel path toward the loading/unloading platform 2 and the mark plate detection sensor 17 detects the mark plate 8, the travel controller 19 stops the travel motor, and the unmanned forklift 4 stops traveling. do. Next, the travel controller 19 drives and controls the travel motor so that the unmanned forklift 4 performs a spin turn and changes its direction by 180°. At this point, the operation of the ultrasonic sensor 12 disposed on the rear side is stopped, and the ultrasonic sensor 11 and photoelectric sensor 13 disposed on the front side are maintained in the operating state. After completing the spin turn, the unmanned forklift 4 moves with the forks 5 in front. When the mark plate detection sensor 17 detects the mark plate 6, the CP
U22 starts counting the output signal of the traveling pulse output device 20 from that point and calculates the distance traveled from that point. Then, a command signal is output to the travel controller 19 to drive and control the travel motor so that the unmanned forklift 4 stops at a cargo transfer position that is a predetermined distance from the forklift truck 4.

Installation position of mark plate 6 and loading/unloading stand 2
The distance is larger than the distance at which the photoelectric sensor 13 can receive a predetermined amount of reflected light from the reflection plate 16. Therefore, the distance between the loading/unloading platform 2 and the unmanned forklift 4 is determined by the photoelectric sensor 1.
The presence or absence of an obstacle is detected by the ultrasonic sensor 11 until the effective range of 3 is reached. When the loading/unloading platform 2 enters the first area A1 of the ultrasonic sensor 11, the traveling speed of the unmanned forklift 4 is changed to a predetermined low speed. From this state, the unmanned forklift 4 continues to move forward, and the unmanned forklift 4 reaches a position where all the photoelectric sensors 13 can receive a predetermined amount of reflected light from the reflector 16. When receiving reflected light from
Based on the detection signal from the photoelectric sensor 13, the CPU 22 switches to a state in which the detection signal from the ultrasonic sensor 11 is disabled. The detection signal of the ultrasonic sensor 11 is not necessarily invalidated immediately after all the photoelectric sensors 13 receive the reflected light from the reflection plate 16, but may be after this state continues for a predetermined period of time. After that, the photoelectric sensor 13 detects the presence or absence of an obstacle between the unmanned forklift 4 and the loading/unloading platform 2.

If an obstacle exists between the unmanned forklift 4 and the loading/unloading table 2, one or more photoelectric sensors 13 will not be able to receive the reflected light from the reflecting plate 16. CPU2
2 outputs a stop command signal to the travel controller 19 when the light reception signal from at least one photoelectric sensor 13 is interrupted, and the unmanned forklift 4 stops. After that, the obstacle is removed and all the photoelectric sensors 13 are connected to the reflector plate 16.
When the CPU 22 receives reflected light from the vehicle, the CPU 22 outputs a travel command signal to the travel controller 19, and the unmanned forklift 4 starts traveling again.

The travel controller 19 outputs a stop command to the travel motor when the unmanned forklift 4 has moved a predetermined distance from the position corresponding to the mark plate 6, and the travel motor is stopped and the brake is applied to stop the unmanned forklift 4. The cargo is transferred by stopping at a stop position appropriate for the transfer of the cargo. As described above, the unmanned forklift 4 is equipped with ultrasonic sensors 11, 12 and a photoelectric sensor 13, and the photoelectric sensor 13 is used to detect obstacles at a position close to the loading/unloading table 2, and at other positions. Ultrasonic sensors 11 and 12 are used to detect obstacles. Therefore, unlike conventional devices, there is no band where obstacles cannot be detected near the loading/unloading table 2, and contact with obstacles during cargo transfer (unloading) operations can be prevented. .

(Embodiment 2) Next, a second embodiment will be described with reference to FIG. This embodiment differs in the method of switching the operating timings of both sensors so that the ultrasonic sensor 11 is disabled and the photoelectric sensor 13 detects an obstacle. In this embodiment, the mark plate 26 is placed at a position corresponding to the mark plate detection sensor 17 when the unmanned forklift 4 reaches a position where all the photoelectric sensors 13 can receive a predetermined amount of reflected light from the reflector 16.
is fixedly placed. Further, when the unmanned forklift 4 is in a position corresponding to the mark plate 26, the second area A2 is set so that the loading/unloading table 2 does not enter the second area A2 of the ultrasonic sensor 11. At the time when the unmanned forklift 4 starts moving forward toward the loading/unloading platform 2, only the ultrasonic sensor 11 is kept in an operating state. Obstacles are detected by the ultrasonic sensor 11 until the unmanned forklift 4 reaches the position corresponding to the mark plate 26. Mark plate detection sensor 1
7 detects the mark plate 26, the CPU 22 disables the detection function of the ultrasonic sensor 11 based on the detection signal, and switches the photoelectric sensor 13 to an active state. After that, the photoelectric sensor 13 detects obstacles.

It should be noted that the present invention is not limited to the above-mentioned embodiments; for example, the photoelectric sensor 13 and the reflector 1
You can change the number of 6 or use the loading/unloading stand 2 as a station.
Alternatively, a reflector 16 may be placed on the side of the storage location 1 for the photoelectric sensor 13.
Instead of providing a plurality of reflectors corresponding to the number of sensors, one horizontally elongated reflector may be provided, or a light-receiving photoelectric sensor may be used as the second sensor instead of the photoelectric sensor 13, and a light-receiving photoelectric sensor may be used as a light-transmitting member on the station side. A floodlight may be provided in place of the reflection plate 16. Moreover, the detection range of the ultrasonic sensor 11 is 2.
Instead of having a structure divided into stages, a one-stage structure may be adopted. In that case, the detection range of the ultrasonic sensor is set narrower than the detection range of the photoelectric sensor 13. Furthermore, the present invention is not limited to the unmanned forklift 4, but may be applied to an unmanned guided vehicle that only transports cargo.

[0019]

As described in detail above, according to the present invention, the first sensor is used when the unmanned vehicle travels between stations, and the first sensor is activated when the unmanned vehicle approaches the station and during loading/unloading work. The two sensors can reliably detect obstacles in front of the unmanned vehicle, and unlike conventional devices, there are no areas where the obstacle detection sensor does not function, preventing contact with obstacles. This ensures safety not only when the unmanned vehicle is running but also during cargo handling operations.

[Brief explanation of the drawing]

FIG. 1 is a schematic side view of an unmanned forklift truck according to a first embodiment.

FIG. 2 is a schematic plan view showing the arrangement relationship of a reflector, a light emitting/receiving sensor, an ultrasonic sensor, and the like.

FIG. 3 is a schematic plan view showing the arrangement relationship between a travel path of an unmanned forklift and stations.

FIG. 4 is a schematic plan view showing the action.

FIG. 5 is a schematic side view showing the action.

FIG. 6 is a schematic side view showing the operation of the second embodiment.

FIG. 7 is a schematic side view of a conventional unmanned forklift.

[Explanation of symbols]

1 Storage location as a station 2 Loading and unloading stand as a station 4 Unmanned forklift as an unmanned vehicle 11 Ultrasonic sensor as a first sensor 13 Photoelectric sensor 1 as a second sensor
6 Reflector plate 22 as a light transmitting member CPU as a switching means

Claims (1)

[Claims] [Claim 1] In an unmanned vehicle that transports cargo between a plurality of stations installed at predetermined locations, the unmanned vehicle is equipped with a system that detects the presence or absence of obstacles in front of the vehicle in its direction of travel by using reflected waves from the obstacles. a first sensor for detection, a plurality of photoelectric second sensors provided on the traveling direction side of the unmanned vehicle when the unmanned vehicle approaches each station, and a predetermined position of each station facing the unmanned vehicle. A safety device for an unmanned vehicle, comprising: a light transmitting member that is provided and sends light toward the second sensor; and a switching means that switches the operating timing of the first sensor and the second sensor.