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 1 includes a plurality of cargo handling vehicles 10, and a first wireless transmitter 30 that constantly broadcasts a first wireless signal to the plurality of cargo handling vehicles 10, wherein each of the cargo handling vehicles 10 includes a wireless receiver 16 that measures a radio wave intensity of the first wireless signal, and a vehicle controller 17 that measures a maximum height of a cargo handling apparatus 12 and controls a cargo handling traveling operation, and the vehicle controller 17 restricts the cargo handling traveling operation when the radio wave intensity of the first wireless signal exceeds a predetermined first threshold and when the maximum height exceeds a predetermined upper limit height.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 7. The cargo handling system 1' includes a forklift 10' that performs cargo handling travel 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 first wireless transmission unit that is provided in the work area and constantly broadcasts a first wireless signal to the plurality of cargo handling vehicles; 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 measures the maximum height of the cargo handling device and controls the cargo handling traveling operation; Equipped with The vehicle control unit When the radio wave intensity of the first wireless signal exceeds a predetermined first threshold and when the maximum height exceeds a predetermined upper limit height, the cargo handling traveling operation is restricted.

[0010] In the cargo handling system, the first wireless signal has unique ID information and includes information about the first threshold value and the upper limit height, The plurality of cargo handling vehicles include: The device may be configured to receive the first wireless signal and obtain the first threshold value and the upper height limit.

[0011] In the cargo handling system, The first wireless transmission unit a plurality of first wireless transmitters that constantly 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] 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.

[0014] 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 a height sensor for detecting the height of the forks; an obstacle sensor provided at an upper portion of the mast for detecting a load on the forks and / or the backrest; The vehicle control unit The device may be configured to store type information of the cargo handling device, and to calculate the maximum height based on the type information, the detection results of the height sensor, and the detection results of the obstacle sensor.

[0015] In the cargo handling system, 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 an additional 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 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.

[0017] 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]

[0018] 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]

[0019] [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] 1A and 1B are diagrams showing the detection range of an obstacle sensor in a forklift truck according to the present invention, in which (A) is a side view and (B) is a plan view. [Figure 5] 1 is a diagram showing a method for measuring the height of a cargo in the present invention. FIG. [Figure 6] 10A and 10B are diagrams for explaining supplementary matters regarding the method for measuring the height of a cargo in the present invention. [Figure 7] FIG. 1 is a diagram showing a conventional cargo handling system. DETAILED DESCRIPTION OF THE INVENTION

[0020] Hereinafter, an embodiment of a cargo handling system according to the present invention will be described with reference to the accompanying drawings.

[0021] Figure 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, and at least one first wireless transmitter 30. The cargo handling system 1 does not require the sensor unit 20' shown in Figure 7.

[0022] 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.

[0023] 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.

[0024] 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.

[0025] 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.

[0026] 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.

[0027] 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.

[0028] 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. The outer mast 13a does not rise and lower.

[0029] 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.

[0030] 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.

[0031] 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.

[0032] 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.

[0033] While receiving the first wireless signal transmitted by the first wireless transmitter 30, the wireless receiver 16 measures the radio wave strength of the first wireless signal at a predetermined cycle. Furthermore, the wireless receiver 16 acquires an "upper limit height" and a "first threshold" (described later) when receiving the first wireless signal, and compares the measured value of the radio wave strength of the first wireless signal with the first threshold. It is preferable to compare the measured value with the first threshold at a predetermined cycle (e.g., every time the radio wave strength 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.

[0034] The vehicle control unit 17 is configured, for example, by a microcomputer, and controls the cargo handling traveling operation. The vehicle control unit 17 also measures the maximum height of the cargo handling device 12, including the load W. The vehicle control unit 17 restricts the cargo handling traveling operation while the first control command signal is being input (when the measured value exceeds the first threshold value) and when the condition that the maximum height exceeds a predetermined upper limit height is met, and releases the restriction on the cargo handling traveling operation when the above condition is no longer met. The restriction on the cargo handling traveling operation and the release of the restriction will be described later.

[0035] The first wireless transmission unit 30 constantly broadcasts a first wireless signal to a plurality of forklifts 10. In Fig. 1, the first wireless transmission unit 30 constantly transmits a common first wireless signal to three forklifts 10 (forklift 10A, forklift 10B, and forklift 10C). A beacon, for example, can be used as the first wireless transmission unit 30.

[0036] The first wireless signal is a signal having ID information unique to the first wireless transmitter 30. The first wireless signal in this embodiment is a Bluetooth (registered trademark) signal, and the signal includes upper limit height information and threshold information for the radio wave intensity of the first wireless signal. Therefore, the wireless receiver 16 that receives the first wireless signal can acquire the upper limit height information and threshold information at the time of reception. Note that the upper limit height information and threshold information may be associated with the unique ID information. In this case, the wireless receiver 16 that receives the first wireless signal can acquire the upper limit height information and threshold information associated with the first wireless signal (ID information) from its own database or the cloud.

[0037] 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.

[0038] 1, the first wireless transmitter 30 continuously transmits the first wireless signal at a predetermined cycle to the forklift 10A, the forklift 10B, and the forklift 10C. Upon receiving the first wireless signal, the wireless receiver 16 of each of the forklifts 10A, 10B, and 10C acquires the upper limit height information and threshold value information contained in the first wireless signal and measures the radio wave intensity of the first wireless signal at a predetermined cycle.

[0039] The upper limit height information includes the upper limit height (upper limit height) of the cargo handling device 12 including the load W when the forklift 10 performs a cargo handling operation. The upper limit height is a height from the road surface and can be set to any value, and the value can also be changed as appropriate. The upper limit height is set, for example, to a height slightly lower than an obstacle above that may collide with the cargo handling device 12 or the load W lifted by the cargo handling device 12 (forks 15). The threshold value information includes a threshold value of the radio wave intensity 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 appropriate.

[0040] 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.

[0041] The vehicle control unit 17 measures the maximum height of the cargo handling device 12, including the load W, at a predetermined timing (for example, when the cargo handling lever is operated). The maximum height is the height from the road surface to the highest point of the cargo handling device 12, including the load W. The vehicle control unit 17 compares the upper limit height with the maximum height at a predetermined cycle while the first control command signal is being input, and restricts the cargo handling travel operation if the maximum height exceeds the upper limit height. That is, the vehicle control unit 17 restricts the cargo handling travel operation if the measured value exceeds the first threshold value and if the maximum height exceeds the upper limit height. In this embodiment, the restriction on the cargo handling travel operation is to prohibit all travel operations and cargo handling operations (except for lowering the mast 13). The restriction can be set in advance in the vehicle control unit 17 and can also be changed as appropriate.

[0042] In the example of FIG. 1, the forklift 10A does not restrict its traveling load handling operations because its measured value exceeds the first threshold but its maximum height is equal to or less than the upper limit height. The forklift 10C does not restrict its traveling load handling operations because its measured value exceeds the upper limit height but its maximum height is equal to or less than the first threshold. The forklift 10B restricts its traveling load handling operations because its measured value exceeds the first threshold and its maximum height exceeds the upper limit height. Specifically, the vehicle control unit 17 of the forklift 10B permits the lowering of the mast 13 and prohibits traveling and loading / unloading operations (except for the lowering of the mast 13).

[0043] As described above, in the cargo handling system 1 according to this embodiment, when the measured value exceeds the first threshold value and the maximum height exceeds the upper limit height, the vehicle control unit 17 restricts the cargo handling travel operation, making it possible to avoid a collision with an overhead obstacle without relying on the operation of the operator of the forklift 10. Furthermore, the cargo handling system 1 according to this embodiment is configured not to restrict the cargo handling travel operation when the possibility of a collision is low (in the case of forklifts 10A and 10C in FIG. 1), making it possible to prevent a decrease in the efficiency of cargo handling work.

[0044] [Modification of the wireless transmission unit] 3A and 3B show plan views of configuration examples of the wireless transmission unit, in which (A) is the configuration example of the embodiment, (B) is the configuration example of the first modification, and (C) is the configuration example of the second modification.

[0045] 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.

[0046] 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.

[0047] 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 a working 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.

[0048] 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.

[0049] 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 each contain a common first threshold value, but may contain first threshold values ​​of different values. The receiving areas (areas inside the solid-line circles) of the two first wireless transmitters 32 may overlap.

[0050] 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.

[0051] 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.

[0052] The second transmission unit (second wireless transmitter 41) constantly broadcasts the second wireless signal to the multiple forklifts 10. For example, a beacon can be used as the second transmission unit (second wireless transmitter 41). The second wireless signal is a signal that has ID information unique to the second wireless transmitter 41. The second wireless signal of this embodiment includes threshold information (second threshold) of the radio wave intensity of the second wireless signal. The threshold information (second threshold) may be associated with the ID information.

[0053] 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.

[0054] In the second modification, 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 common second threshold value, but may contain different second threshold values. Furthermore, the exclusion areas defined by the two second wireless transmitters 41 (areas inside the solid-line circles) may overlap or may be separate. Furthermore, the second wireless transmitter 41 may be set in an area where the first wireless transmitter 33 is unstable.

[0055] In the above embodiment and each modification, the wireless receiver 16 compares the measured value with the threshold value and generates the control command signal, but these processes may be performed by the vehicle control unit 17.

[0056] [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).

[0057] 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 a predetermined period of time. The same applies to the second wireless signal.

[0058] [Maximum height measurement method] Next, a description will be given of a method for measuring the maximum height performed by the vehicle control unit 17. The maximum height is the height from the road surface to the highest point of the cargo handling device 12 including the cargo W.

[0059] In the cargo handling device 12, the location of the highest point varies depending on the height H of the cargo W and the amount of elevation of the mast 13, and is as follows, for example. (1) When the height of the top of the cargo W is equal to or greater than the height of the top of the backrest 14 but less than the height of the top of the mast 13 at low lifting height, the inner mast 13b is the highest point at low lifting height, and the cargo W is the highest point at high lifting height. (2) When the height of the top of the cargo W is lower than the height of the top of the backrest 14 at low lifting height, or when there is no cargo W, the highest point is the inner mast 13b at low lifting height, and the backrest 14 at high lifting height. (3) When the height of the top of the load W is equal to or greater than the height of the top of the mast 13 at low lift height, the load W is always the highest point.

[0060] The low lifting height is a state in which the inner mast 13b is not raised, and the high lifting height is a state in which the inner mast 13b is fully raised. For example, in the case of (2) above, the highest point switches from the inner mast 13b to the backrest 14 at some point during the transition from the low lifting height to the high lifting height. The timing of the switch is determined by the type of cargo handling device 12 (such as the type of mast 13 or the type of backrest 14), so the height of the highest point at that time may be stored in advance in the vehicle control unit 17. The low lifting height may also be a state in which the forks are lifted off the ground (raised by about 150 mm) for travel. Rather, when measuring the height H of the load W, which will be described later, it is preferable to consider this state as the low lifting height.

[0061] The vehicle control unit 17 pre-stores type information of the cargo handling apparatus 12. The type information of the cargo handling apparatus 12 includes information such as the type of mast 13 and the type of backrest 14. More specifically, the information includes information such as the height of the top of the mast 13 at the low and high lifted heights, the thickness of the cross beam connecting the upper ends of the outer masts 13a, and the height of the top of the backrest 14 at the low and high lifted heights. Operation information (operation amount) of the cargo handling lever is also input to the vehicle control unit 17. Furthermore, sensor information (detection results and detection values) of the obstacle sensor 18 and the lifted height sensor, which will be described later, is also input to the vehicle control unit 17.

[0062] The vehicle control unit 17 can calculate the current height of the top of the inner mast 13b and the current height of the top of the backrest 14 based on the above-mentioned operation information, sensor information, and type information of the cargo handling apparatus 12. In other words, the vehicle control unit 17 can calculate the height from the road surface to the highest point of the cargo handling apparatus 12 (maximum height).

[0063] [How to measure cargo height] Next, a description will be given of a method for measuring the height H of the cargo W performed by the vehicle control unit 17. By calculating the height H of the cargo W, the vehicle control unit 17 can calculate the height (maximum height) up to the highest point of the cargo handling device 12 including the cargo W.

[0064] The vehicle control unit 17 measures the height H of the cargo W at a predetermined timing when the lifting height is low or when the lifting height is slightly higher than the low lifting height. The measurement timing may be at a regular interval or at any timing. In order to shorten the time required to measure the maximum height, it is preferable to measure the height H of the cargo W at a timing different from that for measuring the maximum height. For example, the measurement is performed when the current lifting height is within the height range from 0 mm (ground contact) to the height at which the top of the backrest 14 reaches the sensor height (height of the obstacle sensor 18) and while the cargo handling device 12 is performing a raising or lowering operation.

[0065] As shown in Fig. 4(A), the forklift 10 includes an obstacle sensor 18. The obstacle sensor 18 is provided on the upper part of the mast 13 and detects an object ahead (a load W on the fork 15 and / or the backrest 14). In this embodiment, the obstacle sensor 18 is an area sensor (e.g., 2D-LiDAR) and is provided below a cross beam that connects the upper ends of the outer masts 13a.

[0066] As shown in FIG. 4B, the detection range D of the obstacle sensor 18 is (1) Including the tip of the fork 15, (2) The width of the vehicle, i.e., including both the left and right sides of the fork 15, (3) detects the backrest 14 but not the inner mast 13b; The above three conditions are set to be satisfied. Note that a known method can be used to prevent the inner mast 13b from being detected. Furthermore, the above conditions (1) and (2) can be changed or deleted as appropriate depending on the type of cargo W to be handled, etc.

[0067] The forklift 10 is equipped with a height sensor that detects the height of the forks 15. The height sensor detects the height from the road surface to the forks 15 (or to the underside of the pallet). The height sensor may be, for example, a potentiometer-type sensor or an encoder-type sensor provided on the mast 13, or an ultrasonic sensor or a laser sensor provided on the forks 15.

[0068] The vehicle control unit 17, which has started measuring the height of the cargo W, reads out the type information of the cargo handling device 12 stored in advance, acquires operation information (operation amount) of the cargo handling lever, and acquires sensor information (detection results and detection values) of the obstacle sensor 18 and the lifting height sensor.

[0069] Next, the vehicle control unit 17 calculates the height of the obstacle sensor 18 from the type information of the cargo handling device 12. Note that since the height of the obstacle sensor 18 is constant, the vehicle control unit 17 may store the height of the obstacle sensor 18 in advance.

[0070] Next, the vehicle control unit 17 calculates the current height of the top of the backrest 14 from the type information of the cargo handling device 12 and the detection value of the lifting height sensor.

[0071] Next, the vehicle control unit 17 compares the height of the obstacle sensor 18 with the current height of the top of the backrest 14. If the current height of the top of the backrest 14 is lower than the height of the obstacle sensor 18, the vehicle control unit 17 starts the process of calculating the height H of the cargo W. If the current height of the top of the backrest 14 is equal to or higher than the height of the obstacle sensor 18, the operator operates the mast 13 to lower the height of the top of the backrest 14 below the height of the obstacle sensor 18, and then the vehicle control unit 17 starts the process of calculating the height H of the cargo W.

[0072] The vehicle control unit 17, which has started the calculation process for the height H of the cargo W, monitors the detection state of the obstacle sensor 18. Specifically, if the obstacle sensor 18 is currently detecting an obstacle, the vehicle control unit 17 continues monitoring until the obstacle sensor 18 no longer detects an obstacle, for example, by the operator lowering the mast 13. On the other hand, if the obstacle sensor 18 is not currently detecting an obstacle, the vehicle control unit 17 continues monitoring until the obstacle sensor 18 detects an obstacle, for example, by the operator raising the mast 13.

[0073] When the detection of the obstacle sensor 18 is lost due to the lowering operation of the mast 13, or when the detection of the obstacle sensor 18 is regained due to the raising operation of the mast 13, the vehicle control unit 17 performs a calculation to subtract the detection value of the lifting height sensor (height of the fork 15) from the height of the obstacle sensor 18.

[0074] 5(A), when the top of the cargo W is detected by the obstacle sensor 18, the value of the above calculation result (the value obtained by subtracting the height of the forks 15 from the height of the obstacle sensor 18) becomes the height H (= H1) of the cargo W. The vehicle control unit 17 holds the height H (= H1) of the cargo W until the height H (= H1) of the cargo W is updated in the next or subsequent measurement of the height H of the cargo W.

[0075] As shown in Figure 5(A), when the height of the top of the cargo W is equal to or greater than the height of the top of the backrest 14 and less than the height of the top of the mast 13, the highest point of the cargo handling device 12 including the cargo W is the cargo W or the inner mast 13b.

[0076] As shown in Figure 5(B), when the top of the backrest 14 is detected by the obstacle sensor 18, the calculated value obtained by subtracting the detection value of the height sensor from the height of the obstacle sensor 18 is the height from the forks 15 to the top of the backrest 14. Therefore, a value greater than the actual height H (= H2) of the load W is retained as the height H of the load W.

[0077] However, the vehicle control unit 17 can calculate the current height of the top of the backrest 14, and therefore can recognize that the value of the calculation result is the height from the fork 15 to the top of the backrest 14. For this reason, it is possible not to store the calculation result.

[0078] Furthermore, as shown in Figure 5(B), if the height of the top of the cargo W is less than the height of the top of the backrest 14, the highest point of the cargo handling device 12 including the cargo W is the backrest 14 or the inner mast 13b. In this case, the height H of the cargo W is not used to calculate the maximum height, so there is no problem even if the value of the calculation result above is held as the value of the height H of the cargo W.

[0079] As shown in FIG. 5(C), when the obstacle sensor 18 detects the cargo W at a low lift height, the vehicle control unit 17 cannot calculate the height H (= H3) of the cargo W. In this case, the vehicle control unit 17 holds the preset maximum value of the height H of the cargo W as the height H of the cargo W. The maximum value is set to a value equal to or greater than the height H (= H3) of the cargo W.

[0080] 5(C), when the height of the top of the cargo W is equal to or greater than the height of the top of the mast 13 at low lift height, the highest point of the cargo handling apparatus 12 including the cargo W is always the cargo W. In this case, the vehicle control unit 17 calculates the maximum height of the cargo handling apparatus 12 including the cargo W, using the height H of the cargo W as the above maximum value.

[0081] As shown in Figure 6(A), when the forklift 10 detects a load W1 on the first level of the shelf R1, the obstacle sensor 18 may detect a load W2 on the second level of the shelf R1. In this case, the vehicle control unit 17 holds the maximum value as the height H of the load W, as in the case of Figure 5(C). However, when the forklift 10 moves away from the shelf R1, the obstacle sensor 18 no longer detects an object. Therefore, at the point when the obstacle sensor 18 no longer detects an object, the height H of the load W is measured and the held value of the height H of the load W can be updated.

[0082] As shown in Figure 6(B), when the forklift 10 acquires the load W4 at a high lifting height or slightly lower than the high lifting height, it cannot calculate the height H of the load W4 until it acquires the low lifting height or slightly higher than the low lifting height. Therefore, the vehicle control unit 17 calculates the maximum height by using the highest point of the cargo handling device 12 including the load W as the backrest 14. As a result, if the operator performs an operation to raise the mast 13 after acquiring the load W4, the load W4 may collide with an obstacle OB above.

[0083] As a countermeasure, the vehicle control unit 17 uses a cargo presence sensor to set the upper limit value to the height obtained by adding a predetermined ground clearance height (e.g., 200 mm) to the current maximum height (at the time of acquiring cargo W4), and temporarily limits the raising operation of the mast 13 to the upper limit value.

[0084] The load sensor is, for example, a load meter that measures the load of an object on the forks 15, or a photoelectric sensor or ultrasonic sensor that detects an object on the forks 15. When the load sensor detects that a load W (load W3 or load W4) other than the first level of the shelf R2 has been acquired, the vehicle control unit 17 calculates the current maximum height of the cargo handling device 12, sets the height obtained by adding a predetermined clearance height (for example, 200 mm) to the maximum height as the upper limit, and temporarily limits the lifting operation of the mast 13 to the upper limit (for example, until the retention value of the height H of the load W is updated).

[0085] [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.

[0086] 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.

[0087] [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 traveling is prohibited while the forklift 10 is moving forward in a high-lift state, 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 traveling and loading / unloading operations cannot be lifted. In other words, the forklift 10 is in a deadlock state.

[0088] 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.

[0089] 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.

[0090] [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.

[0091] The loading and unloading system of the present invention is a loading and unloading system including 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, and a first wireless transmitting unit provided in the working area for constantly broadcasting a first wireless signal to the plurality of loading and unloading vehicles, wherein 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 measures the maximum height of the loading and unloading device and controls the loading and unloading traveling operations, and 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 and when the maximum height exceeds a predetermined upper limit height.

[0092] 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. [Explanation of symbols]

[0093] 1. Cargo handling system 10, 10A~10C 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 18 Obstacle Sensor 30 First radio transmitter 31~33 First Radio Transmitter 41 Second 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 first wireless transmission unit provided in the work area and configured to constantly broadcast a first wireless signal to the plurality of cargo handling vehicles; 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 measures the maximum height of the cargo handling device and controls the cargo handling traveling operation; Equipped with The vehicle control unit When the radio wave intensity of the first wireless signal exceeds a predetermined first threshold and when the maximum height exceeds a predetermined upper limit height, the cargo handling traveling operation is restricted. A cargo handling system characterized by:

2. the first wireless signal has unique ID information and includes information about the first threshold value and the upper limit height; The plurality of cargo handling vehicles include: receiving the first wireless signal and acquiring the first threshold value and the upper limit height; 2. The cargo handling system according to claim 1.

3. The first wireless transmission unit a plurality of first wireless transmitters that constantly 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. 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.

6. The loading vehicle is a forklift including a mast, a fork, and a backrest as the cargo handling device, The forklift a height sensor for detecting the height of the forks; an obstacle sensor provided at an upper portion of the mast for detecting a load on the forks and / or the backrest; The vehicle control unit The type information of the cargo handling device is stored, and the maximum height is calculated based on the type information, the detection result of the height sensor, and the detection result of the obstacle sensor.

2. The cargo handling system according to claim 1.

7. 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.

7. A cargo handling system according to claim 6.

8. 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.

9. 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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