JPS6137199B2 - - Google Patents

Description

[Detailed description of the invention]

The present invention relates to an entry/exit stage determination device for an unmanned cargo handling device. Cargo handling work in warehouses has mainly been carried out by manually operating cargo handling equipment such as forklifts, but when unmanned, conventionally the loading and unloading stages for loading and unloading cargo were predetermined. Since the instructions were given to the forklift from the outside, the equipment configuration was complicated and expensive. The present invention has been made to eliminate such inconveniences, and aims to provide a loading/unloading stage determination device that can determine which stage should be loaded or unloaded according to the arrangement of cargo at a cargo handling work site. It is something. Embodiments of the present invention will be described below with reference to the drawings. In FIG. 1, a forklift 1, which is an unmanned cargo handling device, has an ultrasonic sensor S ₁ near the tip of its pawl 2, and loads 3 ₂ and 3 placed at the second and third stages of loading and unloading stages. Ultrasonic sensors S ₂ and S ₃ are installed at positions on the mast corresponding to the heights of ₃ , respectively. The forklift 1 is guided by a guide cable (not shown) buried below the running floor in the left-right direction in the figure. The transmitters 5 and 6 are comprised of cables buried on the floor surface in a manner perpendicular to the induction cable,
A magnetic field is generated around it by an alternating current of a predetermined frequency that is constantly flowing. A pick-up coil 30 for detecting the magnetic fields of the transmitters 5 and 6 is attached to the lower part of the vehicle body of the forklift 1.
When the coil 30 is located above the transmitter 5 and when the coil 30 is located above the oscillator 6 as the forklift 1 moves in and out of the warehouse, the coil 30 detects the alternating magnetic fields of the oscillators 5 and 6, respectively. do. The above transmitters 5, 6 and pick-up coil 3
0 functions as a position detection means for detecting the position of the forklift 1 with respect to the loading/unloading position P ₁ in the front row and the position of the forklift with respect to the loading/unloading position P ₃ in the last row shown in the figure. That is, the sensors S ₁ , S ₂ , and S ₃ detect the presence or absence of an object on the same vertical plane in front of the forklift, as described later, and these sensors are placed at the front row loading/unloading position P ₁ . When the forklift 1 moves to a position where it catches the front of the load (FIG. 1 shows this state), the coils 30 detect the magnetic field of the transmitter 5, and the sensors in the last row The installation positions of the transmitters 5 and 6 are such that the coil 30 detects the magnetic field of the transmitter 6 when the forklift 1 moves to a position where it can catch the front of the load placed at the loading/unloading position _P3 . It is set. In addition, each loading/unloading position P ₁ to _{P 3} shown in FIG.
It is set in advance. FIG. 2 shows the output signals of the sensors _S1 to _S3 , the termination detection signal 10 and the start detection signal 12 generated when the pickup coil 30 detects the magnetic fields of the oscillators 5 and 6, respectively, and the input signals described later. This figure shows a determination circuit that determines which loading/unloading stage at each loading/unloading position P ₁ to _{P 3} is possible for loading/unloading based on the loading/unloading switching signal 11 . Note that this judgment circuit is mounted on the forklift 1, and the judgment result is used for cargo handling control for raising and lowering the fork. The ultrasonic switch SW ₁ shown in FIG. 3 causes the sensor S ₁ to repeatedly transmit a transmission pulse T _P with a period _T as shown in FIG. Generate signal G ₁ . If an echo pulse (reception pulse) based on the transmission pulse T _P ' appears during the period in which this signal G ₁ is generated, it is detected. The signal G ₁ rises after the time t ₁ at which the received pulse R′ _P (see b in the same figure) disappears, which is based on the direct wave of the pulse T _P transmitted from the sensor S ₁ , and then rises after the time t ₃ . Its generation timing and time width are set so that it falls after a certain period of time. Note that at the above time t ₃ , forklift 1 is carrying load 3 ₁
How close is the sensor S ₁ to the load 3 ₁
This is determined by considering whether the front side of the image can be captured. Now, when the forklift 1 moves forward to the position shown in Fig. 1, the cargo 3 ₁ placed at the loading/unloading position P ₁
Since the ultrasonic echo pulse R _P reflected from the front surface of the sensor S 1 is received by the sensor S ₁ during the generation period of the signal G ₁ , a signal indicating that the ultrasonic switch SW ₁ has detected the monitoring pulse R _P is generated. Output. However, the lever signal stops the forklift 1 and at the same time activates the other ultrasonic switch via the detection activation circuit 13.
Activate SW ₂ and SW ₃ (for example, supply power to those switches). In addition, if there is no cargo ₃₁ , the echo pulse based on the cargo placed at the bottom of the loading/unloading position _P2
R′ _P (see FIG. 3b) is detected by the sensor S ₁ , but since this pulse does not appear within the current period of occurrence of the signal G ₁ , the forklift 1 is stopped by this pulse. There isn't. The above-mentioned ultrasonic switches SW ₂ and SW ₃ have the same function as the above-mentioned switch SW ₁ , but the
Since S ₂ and S ₃ are located closer to the lift body than sensor S ₁ , they are configured to generate reception distance setting signals G ₂ and G ₃ , respectively, as shown in FIG. 4c. In other words, the signals G ₂ and G 3 have a time width t' ₃ , which is the sum of the round trip propagation time of the ultrasonic wave for the distance from the sensor S ₁ to the mast to the time width _{t 3} of the signal G ₁ .
each is generated. After the forklift 1 is stopped, when the pulse T _P shown in FIG. 4a is transmitted from the sensors S ₂ and S ₃ , the cargo 3 ₂ at the position P ₂ shown in FIG.
and 3 echo pulse R _P based on ₃ (Fig. 4b
) is detected by sensors S ₂ and S ₃ , but this pulse appears after the signals G ₂ and G ₃ disappear due to the relationship with the forklift stop position, so the switches SW ₂ and SW ₃ detect this pulse. is not detected. Therefore, it is confirmed that the second and third tier cargoes do not exist at the loading/unloading position _P1 . In addition, if the second and third tier loads are placed above the load ₃₁ at position P ₁ , echo pulses based on those loads are generated within the generation time of the above signals G ₂ and G ₃ . R _P (Fig. 4b
) appear, the ultrasonic switches SW ₂ and SW ₃ detect this echo pulse R _P , thereby confirming the presence of these cargoes. Note that as mentioned above, the signals G ₁ and G ₂ with a predetermined time width
Since the circuit means for generating G and G ₃ and detecting only the received pulses appearing within these time widths is well known, a description of its configuration will be omitted. Furthermore, as shown in FIGS. 3 and 4, since the received pulse R' _P based on the direct wave of the transmitted pulse T _P does not appear within the generation period of the signal G ₁ and the signals G ₂ and G ₃ , this signal is the switch circuit SW ₁ and
It will not be detected by SW ₂ and SW ₃ . As described above, each of the ultrasonic switches _SW1 ,
SW ₂ and SW ₃ are the first and second on the same vertical plane
The presence or absence of cargo in the third stage is detected, and the detection signal is led to a decoder D and decoded. The cargo handling operations executed in response to this decoded value are shown in the table below. In addition, "0" in the input field indicates no cargo,
“1” indicates that there is a cargo.

[When stocked]

At this time, the logic level of the loading/unloading switching signal provided by means described later is "1". First, consider the case where there is no cargo at any of the above entry/exit positions _P1 to _P2.In this case, regardless of the movement position of the forklift, none of the sensors _S1 to _S3 detect any cargo, but The signal “1” is output from the 0th output terminal of decoder D.
is output continuously. When the forklift advances to a position where the pick-up coil 30 detects the magnetic field of the transmitter 6 and the end detection signal becomes "1", a signal "1" is output from the AND circuit _A1 , and this signal is transmitted to the warehousing stage. Since the signal is input to the selection gate circuit G, the selection gate circuit G outputs a warehousing signal 22 instructing that warehousing is possible at the first warehousing/unloading stage. In addition, when a load is placed on the first loading/unloading stage at position P ₃ (assuming that there is no load placed at positions P ₁ and P ₂ at this time), the first output terminal of decoder D A signal "1" is output from the decoder, and a signal "1" is output from the third output terminal of the same decoder when goods are placed in the first and second loading/unloading stages. In the former case, the warehousing signal 23 from the circuit _G1 indicating that warehousing is possible at the second warehousing/output stage is
In the latter case, the gate circuit _G1 outputs a warehousing signal 24 indicating that warehousing is possible at the third warehousing/output stage. Next, a case will be explained in which a load is placed on each loading/unloading stage at position _P3 . In this case, when the forklift has progressed until the coil 30 detects the magnetic field of the transmitter 6, the sensors _S1 to _S3 detect the loads in each loading/unloading stage at the position _P3 . In other words, the signal "1" is output from the No. 7 output terminal of the decoder D. At this time, since the start end detection signal is "0", a signal "1" is output from the AND circuit shown at the bottom of the gate circuit _G1 , and this signal can be used to enter the first loading/unloading stage. Indicates that When a load is placed on the first stage at position _P2 , the forklift 1 advances until the sensor _S1 detects the front surface of the load, and when the sensor _S1 detects the load, the sensor S ₂ and S ₃ detect that there is no cargo in the second and third loading/unloading stages at the same position P ₂ . At this time, a signal "1" is output from the No. 1 output terminal of decoder D, and this signal is transmitted to the gate circuit.
This determination circuit outputs a signal 23 via _G1 indicating that the second loading/unloading stage is available for storage. In addition, when the cargo is placed in the first and second loading/unloading stages at position _P2 , the
A signal 24 indicating that warehousing is possible at the warehousing/unloading stage is output from the gate circuit _G1 . Next, if a load is placed on each loading/unloading stage at position P ₂ and no freight is placed on each loading/unloading stage at position P ₁ , sensors S _{1 to S 3} The forklift 1 advances to a position where the load can be detected. When the sensors S ₁ to _{S 3} detect the cargo in each stage, a signal 23 is outputted from the 7th output terminal of the decoder and indicates that the cargo can be stored in the first loading/unloading stage based on the signal "1". is output. Also, when a load is placed on the first stage at position _P1 , or when loads are placed on the first and second stages, the output is output from the decoder's No. 1 output terminal and No. 3 output terminal, respectively. Based on the signal "1", signals 23 and 24 are outputted, respectively, instructing that the second and third stages can be entered into and out of the warehouse. Furthermore, if each loading/unloading stage at positions P ₁ , P ₂ , and P ₃ is filled with cargo, each sensor
S ₁ to _{S 3} detect the load in each stage at position P ₁ , and a signal "1" is output from the No. 7 output terminal of decoder D. At this time, the coil 30 detects the magnetic field of the transmitter 5 and the starting end signal 12 becomes "1", and therefore the AND circuit 29 outputs the full signal 29 indicating that there is no space available for stocking. By the way, the position of the forklift at which the instruction to enter the first stage at position P ₂ is given is the same as the position of the forklift at which the instruction to enter the first stage at position P ₃ is given. The movement distance of the forklift to the cargo handling position after the warehousing instruction for position P ₂ is given and the movement distance of the forklift to the cargo handling position after the warehousing instruction for position P ₃ is given must be different from each other. . Therefore, in this embodiment, based on the output of the uppermost AND circuit and the output of the lowermost AND circuit of circuit _G1 ,
A sequence circuit (not shown) is used to vary each movement distance. Furthermore, since the forklift positions at which the warehousing instructions for the second and third tiers at position P ₂ and the warehousing instructions for the first tier at position P ₁ are issued are also the same, in this case as well, the cargo handling position is determined by the above sequence circuit. The distance traveled by each forklift is different. In addition, the judgment for making the above-mentioned moving distance different is based on the output signals of the above-mentioned sensors _S1 to _S4 and the coil 3.
This can be easily done based on an output signal of zero. [At the time of leaving the warehouse] At this time, the logic level of the entry/exit switching signal 11 is "0". Now, as shown in Figure 1, position P ₁
Assuming that a load ₃₁ is placed only on the first loading/unloading stage, only the sensor S1 detects the load when the forklift ₁ advances to the position shown in the figure, and as a result, A signal "1" is output from the first output terminal of the decoder D. One input terminal of each AND circuit in the exit stage selection gate circuit G ₂ receives the above-mentioned input/exit switching signal 11.
(“0”) is inverted by an inverter N and a signal “1” is added thereto. Therefore, the signal “1” output from the decoder D is a signal instructing the unloading of the first stage cargo ₃₁ . It is output as 25. On the other hand, when the cargo is placed on the first and second loading/unloading stages at position P ₁ , a signal "1" is output from the third output terminal of decoder D, and this signal is sent to the gate circuit G ₂ . is output as a signal 26 instructing the second stage to leave the warehouse. In addition, if cargo is placed in each loading/unloading stage at the same position _P1 , the 7th decoder
A signal "1" is outputted from the number output terminal, and this signal is outputted as a signal 27 instructing the unloading of the third stage cargo via the gate circuit _G2 . The determination of the stage to be unloaded at positions P ₂ and P ₃ is made in the same way. Next, when there is no cargo in any of the loading/unloading stages at positions P ₁ , P ₂ and P ₃ , the time point when the coil 30 detects the magnetic field of the oscillator 6, that is, the time point when the termination signal 10 is outputted. Also, the signal "1" is continuously outputted from the output terminal of the decoder D.
Therefore, at the time when the termination signal 10 is output, a signal "1" is output from the AND circuit _A1 , and this signal is applied to any of the positions _P1 , _P2 , and _P3 via the AND circuit _A2 . It is output as a signal 28 indicating that there is no storage, that is, that it is impossible to leave the warehouse. Furthermore, the signal “1” output from the 2nd, 4th, 5th, and 6th output terminals of the decoder D is output from the sensors S ₁ , S ₂ , S ₃
means a false detection of , and those signals are OR circuit OR
It is output as an abnormal signal 21 via the . The operation of the judgment circuit described above is as described above. Therefore, if this judgment circuit is installed in the forklift 1, the forklift itself can judge which stage should be loaded or unloaded. In the above embodiment, an ultrasonic sensor and an ultrasonic switch are used as the cargo detector, but an optical switch or a proximity switch may be used instead.
In addition, the reason why the sensor S ₁ was installed near the claw tip was to enable detection even if a load was loaded on the claw 2 of the forklift 1. Therefore, instead of attaching the sensor S 1 directly to the claw tip, a separate tentacle was installed. It may be provided and attached near its tip. Further, the above-mentioned loading/unloading switching signal 11 can be given in advance by operating a switch or the like, or can be obtained by providing means for detecting whether or not a load is loaded on the claw 2. I can do it. Furthermore, this signal 11 can also be obtained by using the guide cable that guides the forklift 1. That is, a current having a frequency different from that of the current is superimposed on the induction alternating current flowing through the induction cable, and the frequency of this superimposed current is extracted through a filter to obtain a switching signal for entering and exiting the warehouse. I can do it. As is clear from the effects of the above-described embodiments, according to the present invention, the loading/unloading stage at each loading/unloading position can be accurately determined according to the arrangement of cargo at the cargo handling work site. Therefore, there is no need for a means for externally instructing a cargo handling device such as a forklift as to the loading/unloading stage in advance, thereby reducing equipment costs.

[Brief explanation of the drawing]

Fig. 1 is a conceptual diagram illustrating the mode of loading/unloading work to which the device according to the present invention is applied, Fig. 2 is a block diagram showing an embodiment of the device according to the present invention, and Fig. 3 is a diagram of the first stage. A timing chart for explaining the action of the ultrasonic sensor for detecting cargo, Figure 4 is
This is a timing chart for explaining the operation of the ultrasonic sensor that detects the cargo on the first and third stages. 1...Forklift, 3 ₁ , 3 ₂ , 3 ₃ ...
Cargo, S ₁ , S ₂ , S ₃ ... Ultrasonic sensor, 4 ... Pallet, 5 ... Transmitter, 6 ... Transmitter, D ... Decoder, G ₁ ... Receiving stage selection gate circuit, G ₂ ...Exit stage selection gate circuit, 30...Pickup coil.

Claims (1)

[Claims] 1. A load detection device that is provided at the front of the unmanned cargo handling device in correspondence with the height position of each loading/unloading stage, and detects the presence or absence of a load at each of the above height positions within a vertical plane a predetermined distance ahead of the device. a load state detection circuit that detects the arrangement state of the cargo in the loading/unloading stage based on the output of the load detector; and a load state detecting circuit that detects the arrangement state of the cargo in the loading/unloading stage based on the output of the load detector; Determination of loading/unloading stages of an unmanned cargo handling device, comprising a first logic circuit for detecting a loading state, and a second logic circuit for detecting a stage that can be loaded based on the output of the loading state detection circuit and a loading instruction signal. Device.