Cargo handling system

Abstract

To provide a cargo handling system capable of avoiding collision with an upper obstacle without depending on an operation of an operator.SOLUTION: A cargo handling system includes a plurality of cargo handling vehicles 10, a sensor unit 20 that transmits a detection signal, and a first wireless transmission unit 30 that performs broadcast transmission of a first wireless signal to the plurality of cargo handling vehicles 10 while receiving the detection signal, wherein each of the cargo handling vehicles 10 includes a wireless receiver 16 that receives the first wireless signal and measures a radio wave intensity of the first wireless signal, and a vehicle control unit 17 that controls a cargo handling traveling operation, and the vehicle control unit 17 limits the cargo handling traveling operation when the radio wave intensity of the first wireless signal exceeds a predetermined first threshold value.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The present invention relates to a cargo handling system. [Background technology]

[0002] A known conventional cargo handling system is, for example, that described in Patent Document 1. The cargo handling system described in Patent Document 1 is equipped with a detection means for detecting the distance between the ceiling and the upper end of the backrest of the forklift, and is able to stop the elevation of the mast in accordance with the output of the detection means. However, with the cargo handling system described in Patent Document 1, if the forklift travels with the backrest raised and at a high elevation, for example in a location where the ceiling height suddenly drops, there is a possibility that the backrest may collide with the ceiling.

[0003] Another conventional cargo handling system 1' is shown in Figure 4. The cargo handling system 1' includes a forklift 10' that performs cargo handling traveling operations in a predetermined work area, a sensor unit 20' that detects an object present at a predetermined height in the work area, and an alarm unit 21' that outputs an alarm when an object is detected by the sensor unit 20'.

[0004] The sensor unit 20' detects objects (such as a load W lifted by the forks of the forklift 10') at a position slightly lower than overhead obstacles (such as the ceiling of the work area, a gate, or a protrusion). The horizontal detection range of the sensor unit 20' is set to be wider than the range in which the forklift 10' may collide with an overhead obstacle, taking into account the braking distance of the forklift 10'. For example, a 2D-LiDAR is used as the sensor unit 20'.

[0005] In the cargo handling system 1', when the sensor unit 20' detects a load W, the alarm unit 21' outputs an alarm using a buzzer (sound) or a light (light). In response to the alarm, the operator of the forklift 10' lowers the mast or stops the forklift 10'.

[0006] However, if the operator's reaction is delayed, there is a possibility that the cargo W will collide with an obstacle above. On the other hand, if the height of the sensor unit 20' is lowered or the detection range is widened in consideration of the operator's reaction speed, an alarm will be output even when the possibility of a collision is low, which will reduce the efficiency of the cargo handling operation. [Prior art documents] [Patent documents]

[0007] [Patent Document 1] Japanese Utility Model Application Publication No. 2-103098 Summary of the Invention [Problem to be solved by the invention]

[0008] The present invention has been made in view of the above circumstances, and an object of the present invention is to provide a cargo handling system that can avoid collision with an overhead obstacle without relying on the operation of an operator. [Means for solving the problem]

[0009] In order to solve the above problems, the cargo handling system according to the present invention comprises: a plurality of cargo handling vehicles each having a cargo handling device capable of lifting and lowering operations, and performing cargo handling traveling operations including the lifting and lowering operations in a predetermined work area; a sensor unit provided in the work area, which detects the cargo handling device or the cargo lifted by the cargo handling device at a predetermined height in the work area and transmits a detection signal; a first wireless transmission unit that is provided in the work area and that broadcasts a first wireless signal to the plurality of cargo handling vehicles while receiving the detection signal; A cargo handling system comprising: Each of the plurality of cargo handling vehicles is a wireless receiver that receives the first wireless signal and measures the radio wave intensity of the first wireless signal; a vehicle control unit that controls the cargo handling traveling operation, The vehicle control unit When the radio wave intensity of the first wireless signal exceeds a predetermined first threshold, the cargo handling traveling operation is restricted.

[0010] In the cargo handling system, the first wireless signal has unique ID information and is a signal including threshold information of radio wave intensity of the first wireless signal; The plurality of cargo handling vehicles include: receiving the first wireless signal to obtain the threshold information; The threshold information may be configured to include the first threshold.

[0011] In the cargo handling system, The first wireless transmission unit a plurality of first wireless transmitters that broadcast the first wireless signal; The plurality of first wireless transmitters may be configured to be provided in the working area such that areas over which the first wireless signals are received by the wireless receivers overlap or are adjacent to each other.

[0012] The cargo handling system includes: a second wireless transmission unit provided in the work area and configured to constantly broadcast a second wireless signal to the plurality of cargo handling vehicles; The wireless receiver includes: receiving the second wireless signal and measuring the radio wave intensity of the second wireless signal; The vehicle control unit When the radio wave intensity of the second wireless signal exceeds a predetermined second threshold, the restriction on the cargo handling traveling operation may be lifted.

[0013] The cargo handling system includes: a third wireless transmission unit provided in the work area and configured to constantly broadcast a third wireless signal to the plurality of cargo handling vehicles; a receiving area of ​​the third wireless signal is narrower than a receiving area of ​​the first wireless signal; The wireless receiver includes: receiving the third wireless signal and measuring the radio wave intensity of the third wireless signal; The vehicle control unit The loading / unloading traveling operation may be restricted when the radio wave intensity of the third radio signal exceeds a predetermined third threshold and when the radio wave intensity of the first radio signal exceeds the first threshold.

[0014] In the cargo handling system, The vehicle control unit that has restricted the cargo handling traveling operation, The restriction on the cargo handling travel operation can be lifted when the average value of the radio wave strength of the first radio signal falls below the first threshold value, or when the radio wave strength of the first radio signal remains below the first threshold value for a predetermined period of time.

[0015] In the cargo handling system, The loading vehicle is a forklift including a mast, a fork, and a backrest as the cargo handling device, The forklift An accelerator that accelerates when on and decelerates when off; a loading lever that raises the mast when tilted in one direction, lowers the mast when tilted in the other direction, and stops the raising and lowering operation of the mast when returned to a neutral position; The vehicle control unit that has restricted the cargo handling traveling operation, The conditions for releasing the restriction on the cargo handling travel operation can be configured to include a condition that the accelerator is in the off state and the cargo handling lever is in the neutral position.

[0016] In the cargo handling system, The vehicle control unit of the cargo handling vehicle that is not the target of detection by the sensor unit, Even when the radio wave intensity of the first wireless signal exceeds the first threshold, the cargo handling traveling operation may not be restricted.

[0017] In the cargo handling system, The vehicle control unit The travel direction immediately before the restriction on the cargo handling travel operation is stored, and travel in the direction opposite to the travel direction can be excluded from the restriction on the cargo handling travel operation.

[0018] In the cargo handling system, The loading vehicle is The vehicle may be configured to include a release button for temporarily releasing the restriction on the cargo handling traveling operation. [Effects of the Invention]

[0019] According to the present invention, it is possible to provide a cargo handling system that can avoid collision with an overhead obstacle without relying on the operation of an operator. [Brief explanation of the drawings]

[0020] [Figure 1] 1 is a diagram showing a cargo handling system according to the present invention. [Figure 2] 6 is a diagram illustrating the relationship between the radio wave intensity of a first wireless signal and distance. FIG. [Figure 3] FIG. 10 is a diagram illustrating a configuration example (modification) of a wireless transmission unit. [Figure 4] FIG. 1 is a diagram showing a conventional cargo handling system. DETAILED DESCRIPTION OF THE INVENTION

[0021] Hereinafter, an embodiment of a cargo handling system according to the present invention will be described with reference to the accompanying drawings.

[0022] 1 shows a cargo handling system 1 according to one embodiment of the present invention. The cargo handling system 1 includes a plurality of forklifts 10 that perform cargo handling traveling operations in a predetermined work area, at least one sensor unit 20, and at least one first wireless transmitter unit 30.

[0023] The work area is an area within any building such as a factory or warehouse. Above the work area, there are obstacles (not shown) such as a ceiling, gate, protrusions, etc. (hereinafter referred to as "upper obstacles"). In addition, the work area is provided with a plurality of shelves (not shown), on which cargo W, etc., is stored.

[0024] The forklift 10 is, for example, a counterbalance type forklift, and corresponds to the "cargo handling vehicle" of the present invention. The forklift 10 includes a vehicle body 11 and a cargo handling device 12.

[0025] The vehicle body 11 has front and rear wheels at the bottom and a driver's seat and a head guard at the top. The driver's seat is the operator's seat, and the head guard is a protective frame that protects the operator in the driver's seat from falling objects.

[0026] An accelerator and a brake are provided at the front lower part of the driver's seat. The accelerator is an accelerator pedal configured to be operable by an operator in the driver's seat by stepping on it with his / her foot. When the accelerator is in the on state (pedal is depressed), it accelerates the vehicle body 11 in accordance with the amount of pedal depression (accelerator opening), while when it switches from the on state to the off state (pedal is not depressed), it generates weak regenerative braking to decelerate the vehicle body 11. The brake is a brake pedal configured to be operable by an operator in the driver's seat by stepping on it with his / her foot. When the brake is in the on state (pedal is depressed), it generates regenerative braking stronger than the accelerator regenerative braking to decelerate the vehicle body 11, while when it is in the off state, it does not generate regenerative braking. By operating the accelerator and / or brake, the operator can cause the vehicle body 11 to perform traveling operations such as acceleration and deceleration.

[0027] Load handling levers (tilt lever and lift lever) are provided in front of the driver's seat. The load handling levers are connected to the load handling device 12 via a load handling mechanism including a load handling motor provided in the vehicle body 11. The operator can cause the load handling device 12 to perform a load handling operation by operating the load handling levers. The load handling operation and the above-mentioned traveling operation are included in the "load handling traveling operation" of the present invention.

[0028] The cargo handling device 12 includes a mast 13, a backrest 14, a fork 15, a tilt cylinder, and a lift cylinder, and performs cargo handling operations.

[0029] The mast 13 is provided at the front of the vehicle body 11 and raises and lowers the forks 15. The mast 13 comprises an outer mast 13a and an inner mast 13b. The outer mast 13a comprises a pair of left and right guide rails extending vertically, and a cross beam connecting the upper ends of the guide rails. The inner mast 13b is provided inside the guide rails of the outer mast 13a and rises and lowers along the guide rails of the outer mast 13a.

[0030] The backrest 14 is a frame that prevents the cargo W loaded on the forks 15 from tipping backward, and has a lift bracket attached to its lower part. The lift bracket supports the forks 15 and moves up and down along the mast 13. That is, when the mast 13 (inner mast 13b) moves up and down, the backrest 14 (including the lift bracket) and the forks 15 move up and down. The forks 15 are a pair of L-shaped arms on the left and right, and are attached to the front of the backrest 14.

[0031] The tilt cylinder is a hydraulic cylinder for tilting the mast 13 in the forward and backward directions. For example, when the tilt lever is tilted forward, the tilt cylinder extends and the mast 13 tilts forward, and when the tilt lever is tilted backward, the tilt cylinder contracts and the mast 13 tilts backward. When the tilt lever is returned to the neutral position (a position that does not tilt the mast 13 forward or backward), the tilting of the mast 13 stops.

[0032] The lift cylinder is a hydraulic cylinder for raising and lowering the mast 13. For example, when the lift lever is tilted forward, the lift cylinder contracts and the inner mast 13b descends, and when the lift lever is tilted backward, the lift cylinder expands and the inner mast 13b rises. When the lift lever is returned to the neutral position (a position where the inner mast 13b is neither tilted forward nor backward), the raising and lowering of the inner mast 13b stops.

[0033] The forklift 10 includes a wireless receiver 16 and a vehicle control unit 17. In this embodiment, the wireless receiver 16 is provided on the head guard, and the vehicle control unit 17 is provided inside the vehicle body 11.

[0034] While receiving the first wireless signal transmitted by the first wireless transmitter 30, the wireless receiver 16 measures the radio wave intensity of the first wireless signal at a predetermined cycle. The wireless receiver 16 also acquires a "first threshold" (described later) and compares the measured value of the radio wave intensity of the first wireless signal with the first threshold. The comparison of the measured value with the first threshold is preferably performed at a predetermined cycle (e.g., every time the radio wave intensity of the first wireless signal is measured). If the measured value exceeds the first threshold, the wireless receiver 16 outputs a first control command signal to the vehicle control unit 17.

[0035] The vehicle control unit 17 is configured by, for example, a microcomputer, and controls the cargo handling traveling operation. Furthermore, the vehicle control unit 17 restricts the cargo handling traveling operation while the first control command signal is being input, and releases the restriction on the cargo handling traveling operation when the first control command signal is no longer being input. The restriction on the cargo handling traveling operation and the release of the restriction will be described later.

[0036] The sensor unit 20 is provided at a position slightly lower than an overhead obstacle that may collide with the cargo handling device 12 or the load W lifted by the cargo handling device 12 (forks 15), and detects an object (the cargo handling device 12 or the load W) that is present at that position (corresponding to the "predetermined height" of the present invention). The horizontal detection range of the sensor unit 20 is set to a range wider than the range in which a collision with an overhead obstacle may occur, taking into account the braking distance of the forklift 10. In this embodiment, the sensor unit 20 is, for example, a 2D-LiDAR attached to the interior wall of a building.

[0037] When the sensor unit 20 detects an object (the cargo handling device 12 or the cargo W), it transmits a detection signal to the first wireless transmitting unit 30. More specifically, while the sensor unit 20 is detecting the object (the cargo handling device 12 or the cargo W), it continues to transmit the detection signal to the first wireless transmitting unit 30 at a predetermined cycle. When the object (the cargo handling device 12 or the cargo W) is no longer detected due to the lowering operation of the mast 13 or the like, the sensor unit 20 stops transmitting the detection signal.

[0038] The first wireless transmission unit 30 broadcasts a first wireless signal to the multiple forklifts 10 while receiving a detection signal from the sensor unit 20. In Fig. 1, the first wireless transmission unit 30 continues to transmit a common first wireless signal to three forklifts 10 (forklift 10A, forklift 10B, and forklift 10C) while receiving a detection signal from the sensor unit 20. Note that the forklifts 10A, forklift 10B, and forklift 10C have the same configuration.

[0039] The first wireless transmission unit 30 includes, for example, a signal generation and transmission unit that generates and broadcasts the first wireless signal, a power supply unit that receives a detection signal from the sensor unit 20 and supplies power to the signal generation and transmission unit, and a switch means (transistor or relay) interposed in a power supply line connecting the signal generation and transmission unit and the power supply unit. The power supply unit turns on the switch means to supply power to the signal generation and transmission unit while receiving a detection signal from the sensor unit 20. The signal generation and transmission unit continues broadcasting the first wireless signal while power is being supplied. On the other hand, when no detection signal is received from the sensor unit 20, the power supply unit turns off the switch means to stop supplying power to the signal generation and transmission unit. This puts the signal generation and transmission unit in a state (standby state) in which it does not broadcast the first wireless signal. For example, a beacon can be used as the first wireless transmission unit 30.

[0040] The first wireless signal is a signal having ID information unique to the first wireless transmission unit 30. The first wireless signal in this embodiment is a Bluetooth (registered trademark) signal, and the signal includes threshold information for the radio wave strength of the first wireless signal that is preset in the first wireless transmission unit 30. Therefore, the wireless receiver 16 that receives the first wireless signal can acquire the threshold information for the radio wave strength of the first wireless signal at the time of reception. Note that the threshold information for the radio wave strength of the first wireless signal may be associated with the unique ID information. In this case, the wireless receiver 16 that receives the first wireless signal can acquire the threshold information associated with the first wireless signal (ID information) from its own database or the cloud.

[0041] Fig. 2 shows the relationship between the radio wave strength of the first wireless signal and distance. The graph in Fig. 2 shows theoretical values, with the vertical axis representing the radio wave strength of the first wireless signal (received signal strength RSSI [dBm] by wireless receiver 16) and the horizontal axis representing the distance [m] between wireless receiver 16 and first wireless transmitter 30. As shown in Fig. 2, the shorter the distance, the greater the radio wave strength (received signal strength RSSI) and the greater its gradient tends to be. On the other hand, the longer the distance, the smaller the radio wave strength (received signal strength RSSI) and the smaller its gradient tends to be.

[0042] In the case of Fig. 1, when the sensor unit 20 detects a load W on the forklift 10B, it transmits a detection signal to the first wireless transmission unit 30. While receiving the detection signal, the first wireless transmission unit 30 continues to transmit a first wireless signal to the forklifts 10A, 10B, and 10C at a predetermined cycle.

[0043] The wireless receiver 16 of each of the forklifts 10A, 10B, and 10C acquires threshold information contained in the first wireless signal and measures the radio wave strength of the first wireless signal at a predetermined interval. The threshold information includes a threshold value for the radio wave strength of the first wireless signal (hereinafter referred to as the "first threshold value"). The first threshold value is a preset threshold value that can be set to any value and can also be changed as needed.

[0044] Each wireless receiver 16 compares the measured value of radio wave intensity with a first threshold at a predetermined cycle, and if the measured value exceeds the first threshold, outputs a first control command signal to the vehicle control unit 17 provided inside the vehicle body 11. The first control command signal is a signal for restricting the cargo handling traveling operation. If the measured value is equal to or less than the first threshold, the wireless receiver 16 does not output the first control command signal.

[0045] The vehicle control unit 17 restricts the cargo handling traveling operation while the first control command signal is being input. In this embodiment, the restriction on the cargo handling traveling operation is to prohibit all traveling operations and cargo handling operations (except for the lowering operation of the mast 13). The restriction can be set in advance in the vehicle control unit 17 and can also be changed as appropriate.

[0046] In the case of FIG. 1, the measurement values ​​of forklift 10A and forklift 10B exceed the first threshold value, while the measurement value of forklift 10C is equal to or less than the first threshold value. Therefore, vehicle control units 17 of forklift 10A and forklift 10B restrict the traveling operation for cargo handling. Specifically, vehicle control units 17 of forklift 10A and forklift 10B permit the lowering operation of mast 13 and prohibit the traveling operation and cargo handling operation (except the lowering operation of mast 13). On the other hand, vehicle control unit 17 of forklift 10C does not restrict the traveling operation for cargo handling.

[0047] As described above, in the cargo handling system 1 according to this embodiment, when the measured value of the radio wave intensity of the first wireless signal exceeds the first threshold, the vehicle control unit 17 restricts the cargo handling traveling operation, thereby making it possible to avoid a collision with an overhead obstacle without relying on the operation of the operator of the forklift 10. Furthermore, since the first threshold can be set to any value, the cargo handling traveling operation is not restricted when the possibility of a collision is low (in the case of forklift 10C in FIG. 1), and a decrease in the efficiency of the cargo handling work can be prevented.

[0048] [Modification of the wireless transmission unit] Fig. 3 shows plan views of configuration examples of the wireless transmission unit. In Fig. 3, (A) is the configuration example of the above embodiment, (B) is the configuration example of Modification 1, (C) is the configuration example of Modification 2, (D) is the configuration example of Modification 3, and (C) is the configuration example of Modification 4.

[0049] 3(A), in the above embodiment, the wireless transmission unit is configured with a first wireless transmission unit 30, and the first wireless transmission unit 30 is configured with one first wireless transmitter 31. The first wireless transmitter 31 has the same configuration as the first wireless transmission unit 30 described in the above embodiment.

[0050] Here, the first wireless signal from the first wireless transmission unit 30 (first wireless transmitter 31) is easily affected by the surrounding environment, and the radio wave strength (received signal strength RSSI) fluctuates widely. For example, if the first threshold is set so that the cargo handling traveling operation of the forklift 10 inside the solid circle is reliably restricted, the cargo handling traveling operation of the forklift 10 outside the dashed circle will not be restricted, but the cargo handling traveling operation of the forklift 10 between the solid and dashed circles may or may not be restricted. In other words, the area between the solid and dashed circles is an area where control is unstable.

[0051] In the above embodiment, in order to reduce the influence of the surrounding environment, the wireless receiver 16 is provided on the head guard, and the first wireless transmission unit 30 (first wireless transmitter 31) is provided in the work area above the wireless receiver 16. This eliminates obstacles between the first wireless transmission unit 30 (first wireless transmitter 31) and the wireless receiver 16 as much as possible.

[0052] 3(B), in Modification 1, the wireless transmission unit is configured with a first wireless transmission unit 30, and the first wireless transmission unit 30 is configured with two first wireless transmitters 32. The first wireless transmitter 32 has the same configuration as the first wireless transmitter 31, except that the first threshold value is set to a larger value than that of the first wireless transmitter 31, and the restricted range of the cargo handling traveling operation is narrower. The narrower the restricted range, the smaller the fluctuation range of the radio wave intensity (received signal strength RSSI), and therefore the configuration of Modification 1 has a smaller unstable area than the configuration of the above embodiment.

[0053] The two first wireless transmitters 32 are provided in a working area above the wireless receiver 16 so that the areas inside the solid-line circles (corresponding to the "receiving areas" of the present invention) are adjacent to each other. The first wireless signals transmitted from the two first wireless transmitters 32 contain a common first threshold value, but may contain different first threshold values. The receiving areas (areas inside the solid-line circles) of the two first wireless transmitters 32 may overlap.

[0054] As shown in Fig. 3(C), in Modification 2, the wireless transmission unit is made up of a first wireless transmission unit 30 and a second wireless transmission unit, the first wireless transmission unit 30 is made up of one first wireless transmitter 33, and the second wireless transmission unit is made up of two second wireless transmitters 41. Note that in Fig. 3(C), the outer boundary line (broken circle) of the unstable area of ​​the first wireless transmitter 33 is omitted.

[0055] The first wireless transmitter 33 has the same configuration as the first wireless transmitter 31, except that the first threshold value is set to a smaller value than that of the first wireless transmitter 31, and the restricted range of the cargo handling traveling operation is a wider range.

[0056] The second transmission unit (second wireless transmitter 41) constantly broadcasts the second wireless signal to multiple forklifts 10. That is, since the second transmission unit (second wireless transmitter 41) is not linked to the sensor unit 20, it continues to transmit the second wireless signal even when it is not receiving a detection signal from the sensor unit 20. A beacon, for example, can be used as the second transmission unit (second wireless transmitter 41). The second wireless signal is a signal similar to the first wireless signal and includes ID information unique to the second wireless transmitter 41. The second wireless signal of this embodiment includes threshold information (second threshold) for the radio wave intensity of the second wireless signal. Note that the threshold information (second threshold) may be associated with the ID information.

[0057] The wireless receiver 16 acquires threshold information (second threshold) included in the second wireless signal and measures the radio wave intensity of the second wireless signal at a predetermined cycle. The wireless receiver 16 compares the measured value of the radio wave intensity of the second wireless signal with the second threshold at a predetermined cycle, and if the measured value exceeds the second threshold, outputs a second control command signal to the vehicle control unit 17 provided inside the vehicle body 11. The second control command signal is a signal for lifting the restriction on the cargo handling travel operation. In other words, the vehicle control unit 17 lifts the restriction on the cargo handling travel operation while the wireless receiver 16 is receiving the second wireless signal.

[0058] In Modification 2, an exclusion area where the restriction on cargo handling travel operations is lifted can be set within the area where cargo handling travel operations are restricted. Note that the second wireless signals transmitted from the two second wireless transmitters 41 each contain a second threshold value of a common value, but may contain second threshold values ​​of different values. Furthermore, the exclusion areas (areas inside the solid-line circles) defined by the two second wireless transmitters 41 may overlap.

[0059] As shown in Fig. 3(D), in Modification 3, the wireless transmission unit is made up of a first wireless transmission unit 30 and a third wireless transmission unit, the first wireless transmission unit 30 is made up of one first wireless transmitter 33, and the third wireless transmission unit is made up of two third wireless transmitters 51. Note that in Fig. 3(D), the outer boundary line (broken circle) of the unstable area of ​​the first wireless transmitter 33 is omitted.

[0060] The third transmission unit (third wireless transmitter 51), like the second transmission unit (second wireless transmitter 41), constantly broadcasts a third wireless signal to multiple forklifts 10. A beacon, for example, can be used as the third transmission unit (third wireless transmitter 51). The third wireless signal is a signal similar to the second wireless signal, and is a signal having ID information unique to the third wireless transmitter 51. The third wireless signal of this embodiment includes threshold information (third threshold) for the radio wave intensity of the third wireless signal. Note that the threshold information (third threshold) may be associated with the ID information.

[0061] The wireless receiver 16 acquires the threshold information (third threshold) included in the third wireless signal and measures the radio wave intensity of the third wireless signal at a predetermined cycle. The wireless receiver 16 compares the measured value of the radio wave intensity of the third wireless signal with the third threshold at a predetermined cycle, and if the measured value exceeds the third threshold, outputs a third control command signal to the vehicle control unit 17 provided inside the vehicle body 11 of the wireless receiver 16.

[0062] In the third modification, the vehicle control unit 17 restricts the cargo handling traveling operation when the first control command and the third control command signal are input, in other words, when the measurement value of the first wireless signal exceeds the first threshold and the measurement value of the third wireless signal exceeds the third threshold. The configuration of the third modification makes it possible to reduce the unstable area as in the first modification and to reduce the number of wireless transmitters linked to the sensor unit 20.

[0063] As shown in Fig. 3(E), in Modification 4, the wireless transmission unit is made up of a first wireless transmission unit 30 and a third wireless transmission unit, the first wireless transmission unit 30 is made up of one first wireless transmitter 33, and the third wireless transmission unit is made up of three third wireless transmitters 51, 52, and 53. The third wireless transmitters 52 and 53 have the same configuration as the third wireless transmitter 51. Note that in Fig. 3(D), the outer boundary lines (broken circles) of the unstable areas of the first wireless transmitter 33 and the third wireless transmitters 51, 52, and 53 are omitted.

[0064] Because the third wireless signal is a signal that has ID information unique to the third wireless transmitters 51, 52, and 53, the wireless receiver 16 can identify the third wireless signal from each of the third wireless transmitters 51, 52, and 53. The wireless receiver 16 outputs three types of third control command signals (third control command signal A, third control command signal B, and third control command signal C) corresponding to the third wireless signals from the third wireless transmitters 51, 52, and 53 to the vehicle control unit 17. The third control command signal A, third control command signal B, and third control command signal C are all signals for restricting the cargo handling traveling operation, but the content of the restrictions varies from one to another. The content of each restriction can be set in advance in the vehicle control unit 17.

[0065] That is, vehicle control unit 17 can vary the restrictions on cargo handling traveling operations depending on whether the first control command and third control command signal A are input, the first control command and third control command signal B are input, or the first control command and third control command signal C are input. Furthermore, sensor unit 20 can set a detection range for an object (load handling device 12 or load W) for each receiving area of ​​third wireless transmitters 51, 52, and 53, thereby enabling control (restrictions on cargo handling traveling operations) for each area.

[0066] In the above embodiment and each modified example, wireless receiver 16 compares the measured value with thresholds (first to third thresholds) and generates a control command signal, but these processes may also be performed by vehicle control unit 17.

[0067] [Measures to deal with fluctuations in radio wave strength] As described above, the first wireless signal is easily affected by the surrounding environment, and the radio wave strength (received signal strength RSSI) fluctuates widely. Therefore, if the measurement value of the first wireless signal is used as is in the forklift 10, there is a risk that the restriction on the cargo handling traveling operation will be repeatedly turned on and off (enabled and disabled).

[0068] To address this issue, wireless receiver 16 may use the average value of the radio wave intensity of the first wireless signal over a predetermined period of time (e.g., several seconds) as a measurement value. Alternatively, vehicle control unit 17 may restrict the cargo handling traveling operation when the first control command is continuously input for a predetermined period of time, or may release the restriction on the cargo handling traveling operation when the first control command is no longer continuously input for the predetermined period of time. The same applies to the second wireless signal and the third wireless signal.

[0069] [Measures for sudden acceleration and sudden movements] If the mast 13 is lowered with the accelerator on after the restriction on cargo handling travel has been imposed and the restriction on cargo handling travel is then released, the forklift 10 may suddenly accelerate. Also, if the restriction on cargo handling travel is imposed in an unstable area and the restriction on cargo handling travel is then released with the tilt lever tilted forward or backward, the mast 13 may suddenly tilt forward or backward.

[0070] To address this issue, if the conditions for releasing the restrictions on the cargo handling traveling operation are met while the operator is operating the accelerator or performing a cargo handling operation (excluding the lowering operation of the mast 13), the vehicle control unit 17 sets an additional condition. Specifically, the vehicle control unit 17 sets the additional condition that the accelerator is in the OFF state and the cargo handling lever is returned to the neutral position, and when this additional condition is met in addition to the above-mentioned release condition, the restriction on the cargo handling traveling operation is released.

[0071] [Measures for vehicles subject to restrictions] In the above embodiment, all forklifts 10 in the area where the measured radio wave intensity exceeds the first threshold are subject to the restriction on their cargo handling travel. In the case of Figure 1, the forklift 10A is subject to the restriction on its cargo handling travel, even though there is no possibility of it colliding with an obstacle above.

[0072] As a countermeasure, it is conceivable to set vehicle conditions that are exempt from the restriction. For example, a load presence sensor may be provided on the forklift 10, and a forklift 10 that does not carry a load W may be exempt from the restriction. Alternatively, a height sensor may be provided on the forklift 10, and a forklift 10 with a height equal to or less than a predetermined value may be exempt from the restriction. Alternatively, a forklift 10 whose mast 13 is not a high-mast type may be exempt from the restriction. For a forklift 10 that is exempt from the restriction, no restrictions are imposed on its cargo handling travel operations even if the measured radio wave intensity exceeds the first threshold. Note that, depending on the environment of the work area, it may be necessary to set a combination of multiple vehicle conditions that are exempt from the restriction.

[0073] [Countermeasures against deadlocks] When a forklift 10 is subject to the restriction on its traveling and loading / unloading operations, it is prohibited from traveling and loading / unloading operations (except for lowering the mast 13). For this reason, if the sensor unit 20 detects an obstacle while the forklift 10 is moving forward in a high-lift state and the traveling operation is prohibited, for example, if there is an obstacle under the forks 15 (e.g., on the road surface) when the forklift 10 stops traveling, the mast 13 cannot be lowered and the restriction on the traveling and loading operation cannot be lifted. In other words, the forklift 10 enters a deadlock state.

[0074] As a countermeasure, the vehicle control unit 17 may store the travel direction (forward or reverse) immediately before the cargo handling travel operation is restricted, and exclude travel in the opposite direction to the immediately preceding travel direction from the restrictions on cargo handling travel operation. For example, if the immediately preceding travel direction was forward, reverse travel is excluded from the restrictions on cargo handling travel operation, and if the immediately preceding travel direction was reverse, forward travel is excluded from the restrictions on cargo handling travel operation. This allows the operator to move the forklift 10 to a position where there are no obstacles under the forks 15, thereby eliminating the deadlock state.

[0075] Alternatively, the forklift 10 may be provided with a release button that temporarily releases the restrictions on the cargo handling traveling operation. When the operator operates the release button, the restrictions on the cargo handling traveling operation are temporarily released (for example, for a few minutes). This allows the operator to move the forklift 10 to a position where there are no obstacles under the forks 15, thereby eliminating the deadlock state.

[0076] [Other variations] Although the embodiment of the cargo handling system according to the present invention has been described above, the present invention is not limited to the above embodiment.

[0077] The loading and unloading system of the present invention includes a plurality of loading and unloading vehicles equipped with loading and unloading devices capable of lifting and lowering operations and performing loading and unloading traveling operations including lifting and lowering operations in a predetermined working area; a sensor unit provided in the working area that detects loading and unloading devices located at a predetermined height in the working area or cargo lifted by the loading and unloading devices and transmits a detection signal; and a first wireless transmitter unit provided in the working area that broadcasts a first wireless signal to the plurality of loading and unloading vehicles while receiving the detection signal.Each of the plurality of loading and unloading vehicles is equipped with a wireless receiver that receives the first wireless signal and measures the radio wave strength of the first wireless signal, and a vehicle control unit that controls the loading and unloading traveling operations.The vehicle control unit can be configured as appropriate so long as it restricts the loading and unloading traveling operations when the radio wave strength of the first wireless signal exceeds a predetermined first threshold.

[0078] For example, although the above embodiment has been described using a counterbalance type forklift as an example of the cargo handling vehicle of the present invention, it may also be a reach type forklift or another type of forklift.Furthermore, the cargo handling vehicle of the present invention is not limited to a forklift, and may be a vehicle other than a forklift (for example, a transport vehicle) as long as it is equipped with a cargo handling device that can be raised and lowered.

[0079] The sensor unit of the present invention may be configured with multiple area sensors (e.g., 2D-LiDAR), may be configured with a combination of other sensors, or may be configured with a camera that can detect cargo handling equipment or cargo by performing image processing. The sensor unit of the present invention may also include an alarm unit (e.g., alarm unit 21' shown in FIG. 4) that outputs an alarm using a buzzer (sound) or light (light) while transmitting a detection signal. [Explanation of symbols]

[0080] 1. Cargo handling system 10. Forklift 11 Vehicle body 12 Cargo handling equipment 13 Mast 13a Outer Mast 13b Inner mast 14 Backrest 15 Fork 16. Radio receiver 17 Vehicle control unit 20 Sensor section 30 First radio transmitter 31~33 First Radio Transmitter 41 Second Radio Transmitter 51~53 Third Radio Transmitter

Claims

1. a plurality of cargo handling vehicles each having a cargo handling device capable of lifting and lowering operations, and performing cargo handling traveling operations including the lifting and lowering operations in a predetermined work area; a sensor unit provided in the work area, which detects the cargo handling device or the cargo lifted by the cargo handling device at a predetermined height in the work area and transmits a detection signal; a first wireless transmission unit that is provided in the work area and that broadcasts a first wireless signal to the plurality of cargo handling vehicles while receiving the detection signal; A cargo handling system comprising: Each of the plurality of cargo handling vehicles is a wireless receiver that receives the first wireless signal and measures the radio wave intensity of the first wireless signal; a vehicle control unit that controls the cargo handling traveling operation, The vehicle control unit When the radio wave intensity of the first wireless signal exceeds a predetermined first threshold, the cargo handling traveling operation is restricted. A cargo handling system characterized by:

2. the first wireless signal has unique ID information and is a signal including threshold information of radio wave intensity of the first wireless signal; The plurality of cargo handling vehicles include: receiving the first wireless signal to obtain the threshold information; The threshold information includes the first threshold.

2. The cargo handling system according to claim 1.

3. The first wireless transmission unit a plurality of first wireless transmitters that broadcast the first wireless signal; The plurality of first wireless transmitters are provided in the working area such that reception areas of the first wireless signals by the wireless receivers overlap or are adjacent to each other.

2. The cargo handling system according to claim 1.

4. a second wireless transmission unit provided in the work area and configured to constantly broadcast a second wireless signal to the plurality of cargo handling vehicles; The wireless receiver includes: receiving the second wireless signal and measuring the radio wave intensity of the second wireless signal; The vehicle control unit When the radio wave intensity of the second wireless signal exceeds a predetermined second threshold, the restriction on the cargo handling traveling operation is lifted.

2. The cargo handling system according to claim 1.

5. a third wireless transmission unit provided in the work area and configured to constantly broadcast a third wireless signal to the plurality of cargo handling vehicles; a reception area of ​​the third wireless signal is narrower than a reception area of ​​the first wireless signal; The wireless receiver includes: receiving the third wireless signal and measuring the radio wave intensity of the third wireless signal; The vehicle control unit When the radio wave intensity of the third radio signal exceeds a predetermined third threshold and when the radio wave intensity of the first radio signal exceeds the first threshold, the cargo handling traveling operation is restricted.

2. The cargo handling system according to claim 1.

6. The vehicle control unit that has restricted the cargo handling traveling operation, When an average value of the radio wave intensity of the first radio signal falls below the first threshold value, or when the radio wave intensity of the first radio signal remains below the first threshold value for a predetermined period of time, the restriction on the cargo handling traveling operation is released.

2. The cargo handling system according to claim 1.

7. The loading vehicle is a forklift including a mast, a fork, and a backrest as the cargo handling device, The forklift An accelerator that accelerates when on and decelerates when off; a loading lever that raises the mast when tilted in one direction, lowers the mast when tilted in the other direction, and stops the raising and lowering operation of the mast when returned to a neutral position; The vehicle control unit that has restricted the cargo handling traveling operation, The conditions for releasing the restriction on the cargo handling travel operation include an additional condition that the accelerator is in the off state and the cargo handling lever is in the neutral position.

2. The cargo handling system according to claim 1.

8. The vehicle control unit of the cargo handling vehicle that is not the target of detection by the sensor unit, Even if the radio wave intensity of the first wireless signal exceeds the first threshold, the cargo handling traveling operation is not restricted.

2. The cargo handling system according to claim 1.

9. The vehicle control unit The traveling direction immediately before the restriction on the cargo handling traveling operation is stored, and traveling in the direction opposite to the traveling direction is excluded from the restriction on the cargo handling traveling operation.

2. The cargo handling system according to claim 1.

10. The loading vehicle is A release button is provided to temporarily release the restriction on the cargo handling travel operation.

2. The cargo handling system according to claim 1.

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