Unmanned transport vehicles

Abstract

To provide an unmanned transport vehicle capable of automatic travel control taking slip into account by the vehicle itself.SOLUTION: The unmanned transport vehicle 1 automatically travels along a predetermined route R that is composed of a plurality of sections D, and is equipped with a driving control unit 12 that controls the driving of the vehicle based on operation data W indicating operating actions for each section D, an actual driving distance detection unit (detection unit) 14 that detects an actual driving distance traveled by the vehicle on the road surface by the driving control unit, and a determination unit 15 that compares the actual driving distance with a reference driving distance for each section D and determines a section D where the difference between the actual driving distance and the reference driving distance exceeds a predetermined threshold value to be a slip section Ds, and the driving control unit 12 limits the driving speed when driving through a section determined to be the slip section Ds.SELECTED DRAWING: Figure 2

Description

Technical Field

[0001] The present disclosure relates to an automated guided vehicle.

Background Art

[0002] In recent years, automated guided vehicles have been introduced for transporting goods, etc. The automated guided vehicle automatically travels between a loading position and an unloading position of goods, for example, according to preset operation data. As a technology for controlling the automatic driving of an automated guided vehicle, there is, for example, a control system for an unmanned vehicle described in Patent Document 1. In this conventional control system for an unmanned vehicle, the slip amount when the unmanned vehicle travels is predicted based on road surface state data, and a driving permission area for the unmanned vehicle or a stop point in the driving permission area is set according to the predicted slip amount.

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0004] In the above-described conventional control system for an unmanned vehicle, examples of the road surface state data used for predicting the slip amount include data related to the moisture of the road surface, position data of a point set by an operator, data related to the amount of water sprayed by a watering vehicle, and imaging data of the road surface by a camera. However, when using these data, a higher-level system and equipment for acquiring the data are required, which may lead to a complication in the configuration and an increase in the manufacturing cost even in an unmanned vehicle.

[0005] The present disclosure has been made to solve the above problems, and an object thereof is to provide an automated guided vehicle capable of automatic driving control considering slip by the vehicle itself.

Means for Solving the Problems

[0006] The gist of the present disclosure is as follows in [1] to [3].

[0007] [1] An automated guided vehicle that automatically travels along a predetermined path composed of a plurality of sections, comprising: a travel control unit that controls the travel of the vehicle based on travel data indicating the operation of each section; a detection unit that detects the actual travel distance traveled by the vehicle on the road surface by the travel control unit; and a determination unit that compares the actual travel distance with a reference travel distance for each section and determines a section where the difference between the actual travel distance and the reference travel distance exceeds a predetermined threshold as a slip section, wherein the travel control unit limits the travel speed when traveling in the section determined to be the slip section.

[0008] In this automated guided vehicle, based on the comparison between the actual travel distance and the reference travel distance for each section, the presence or absence of a slip section in the section on the path is determined. For the section determined to be the slip section, by limiting the travel speed, it is possible to prevent the vehicle from deviating from the path. This automated guided vehicle has a detection unit that detects the actual travel distance, and by storing the reference travel distance for each section in advance on the vehicle side, it is possible to perform automatic travel control considering slip by the vehicle itself. Since the data necessary for determining the slip section can be acquired by the vehicle itself, an upper-level system or facility for acquiring data is not required, and an increase in configuration complexity and manufacturing cost can be avoided.

[0009] [2] The automated guided vehicle according to [1], wherein the travel control unit increases the speed limit amount when traveling in the section determined to be the slip section as the difference between the actual travel distance and the reference travel distance is larger. By such control, it is possible to more reliably prevent the vehicle from deviating from the path when traveling in the slip section.

[0010] [3] When a predetermined time has elapsed since the determination unit determined the slip section, the determination of the slip section in the section is cancelled for the driverless transport vehicle according to [1] or [2]. By cancelling the determination of the slip section after the predetermined time has elapsed, it is possible to suppress the running of the driverless transport vehicle from being restricted more than necessary. Further, when cancelling the determination of the slip section, since it is not necessary to acquire data from a higher-level system or equipment, it is possible to avoid complication of the configuration and an increase in manufacturing cost.

Effect of the Invention

[0011] According to the present disclosure, it is possible to perform automatic driving control considering slip by the vehicle itself.

Brief Description of the Drawings

[0012]

Figure 1

Figure 2

Figure 3

Figure 4

Figure 5

Figure 6

Mode for Carrying Out the Invention

[0013] Hereinafter, a preferred embodiment of a driverless transport vehicle according to one aspect of the present disclosure will be described in detail with reference to the drawings.

[0014] FIG. 1 is a schematic diagram showing a transportation system using an unmanned transport vehicle according to an embodiment of the present disclosure. The transportation system S is configured to include one or more unmanned transport vehicles 1. The unmanned transport vehicle 1 is a vehicle that automatically travels on a predetermined route R composed of a plurality of sections D. The unmanned transport vehicle 1 is used, for example, for transporting luggage and reciprocates on a predetermined route R connecting the luggage loading position and the unloading position.

[0015] In the present embodiment, a guided driving type vehicle is exemplified as the unmanned transport vehicle 1. In the example of FIG. 1, the route R is a guided driving route, and a plurality of RFID tags 2 are arranged in order from the start point to the end point of the route R. Each of the RFID tags 2 stores identification information for uniquely identifying the tag. Examples of the identification information include tag numbers (No. 1, No. 2, No. 3, No. 4...).

[0016] In the automatic driving of the unmanned transport vehicle 1, an input operation (so-called input operation) for designating the route R to the unmanned transport vehicle 1 is performed. In this input operation, operation data W (see FIG. 4) described later is input to the unmanned transport vehicle 1. The unmanned transport vehicle 1 sequentially detects the RFID tags 2 arranged on the route R while traveling on the route R. The unmanned transport vehicle 1 refers to the operation data W based on the identification information of the detected RFID tag 2 and executes the operation specified by the operation data W.

[0017] FIGS. 2(a) to (c) are schematic diagrams showing how the unmanned transport vehicle 1 travels on a predetermined route R. In FIGS. 2(a) to 2(c), the state where the unmanned transport vehicle 1 travels in the section D between the RFID tag 2 of No. n and the RFID tag 2 of No. (n + 1) is shown. The nth section D is the section from the position of the nth RFID tag 2 to the position of the (n + 1)th RFID tag 2. In the example of FIG. 2(a), in the nth section D, after detecting the RFID tag 2 of No. n, the unmanned transport vehicle 1 curves to the right at a predetermined speed and detects the next RFID tag 2 of No. (n + 1) after the curve.

[0018] As shown in Fig. 2(a), the driverless transport vehicle 1 normally travels on a track along the route R. However, when the road surface of the route R is wet with water or oil, or when the road surface is frozen, slipping is likely to occur during travel. As shown in Fig. 2(b), it is conceivable that the travel track of the driverless transport vehicle 1 deviates from the route R. In the example of Fig. 2(b), the travel track of the driverless transport vehicle 1 bulges greatly outside the curve. However, even on a straight track, if slipping occurs during travel, it is conceivable that the driverless transport vehicle 1 will exceed the position where it should originally stop.

[0019] To address such problems, the driverless transport vehicle 1 determines whether the section D is a section where slipping occurs (slipping section Ds). For the section D determined to be the slipping section Ds, automatic driving control is performed by limiting the traveling speed so that the traveling track is a track along the route R, as shown in Fig. 2(c). The driverless transport vehicle 1 is configured to be able to acquire by itself the data necessary for determining the slipping section Ds, eliminating the need for a higher-level system or facility for data acquisition.

[0020] Hereinafter, the specific configuration of the driverless transport vehicle 1 will be described. Fig. 3 is a block diagram showing the configuration of the driverless transport vehicle 1. As shown in Fig. 3, the driverless transport vehicle 1 includes a tag detection unit 11, a travel control unit 12, an operation data storage unit 13, an actual travel distance detection unit 14, and a determination unit 15. Physically, the travel control unit 12, the operation data storage unit 13, and the determination unit 15 are constituted by a computer system equipped with a storage device such as a RAM and a ROM, a processor (arithmetic circuit) such as a CPU, a communication interface, and the like.

[0021] The tag detection unit 11 is a part that detects the RFID tag 2 arranged on the route R. A known RFID reader can be used for the tag detection unit 11. The tag detection unit 11 detects the RFID tag 2, reads out the identification information stored in the RFID tag 2, and outputs it to the travel control unit 12 and the determination unit 15.

[0022] The travel control unit 12 is a part that controls the travel of the vehicle 1. When the travel control unit 12 receives the identification information of the RFID tag 2 from the tag detection unit 11, it refers to the operation data W stored in the operation data storage unit 13 based on the identification information, and controls the operation of the travel device (such as the motor and axles) of the vehicle 1 according to the operation specified by the operation data W.

[0023] The operation data storage unit 13 is a part that stores the operation data W. The operation data W is data indicating the operation for each section D. The operation data W is stored in the operation data storage unit 13, for example, in the input operation of designating the route R for the automated guided vehicle 1.

[0024] FIG. 4 is a diagram showing an example of the operation data W. In the example of FIG. 4, in the operation data W, the "Course No.", which is the identification information of the route R, the "RFID Tag No.", which is the identification information of the RFID tag 2, the "operation" required for the automated guided vehicle 1 at the time of tag detection, the "travel speed" when traveling through the section D, and the "reference travel distance" when traveling through the section D are associated with each other. Also, in the example of FIG. 4, in addition to the above-mentioned each information, the operation data W is associated with the judgment information indicating whether the section D is a slip section Ds and the limit information indicating the speed limit amount in the slip section Ds.

[0025] The judgment unit 15 is a part that judges whether the section D traveled by the automated guided vehicle 1 is a slip section Ds or not. When the judgment unit 15 receives the identification information of the RFID tag 2 from the tag detection unit 11, it refers to the operation data W stored in the operation data storage unit 13 based on the identification information, and reads out the reference travel distance in the section D specified by the identification information.

[0026] On the one hand, when the determination unit 15 receives the identification information of the next RFID tag 2 from the tag detection unit 11, it reads out the actual travel distance in the section D from the next RFID tag 2 to the next RFID tag 2 from the actual travel distance detection unit 14. The actual travel distance detection unit 14 is constituted by, for example, an encoder or a potentiometer provided on the drive wheels of the automated guided vehicle 1. The determination unit 15 compares the actual travel distance in the section D with the reference travel distance, and when the difference between the actual travel distance and the reference travel distance exceeds a predetermined threshold value, it determines that the section D is a slip section Ds.

[0027] In the example of FIG. 4, the reference travel distance of the section D from the RFID tag 2 of No. 2 to the RFID tag 2 of No. 4 is 8 m. For this section D, when the threshold value of the difference between the actual travel distance and the reference travel distance is set to, for example, 50 cm, the determination unit 15 determines that the section D is not a slip section Ds when the actual travel distance in the section D is 8 m or more and 8 m 50 cm or less, and determines that the section D is a slip section Ds when the actual travel distance in the section D exceeds 8 m 50 cm.

[0028] When the determination unit 15 determines that the section D is a slip section Ds, it refers to the operation data W stored in the operation data storage unit 13, attaches a flag (the "*" mark in the example of FIG. 4) indicating that the section D is a slip section Ds to the identification information of the RFID tag 2, and sets the speed limit amount in the slip section Ds. In the present embodiment, when determining the slip section Ds, the determination unit 15 sets the speed limit amount to be larger as the difference between the actual travel distance and the reference travel distance is larger.

[0029] The above-described travel control unit 12 causes the automated guided vehicle 1 to travel in a state where the travel speed is lower than the original travel speed in accordance with the limit speed amount set by the determination unit 15 for the section D determined to be the slip section Ds. Further, the travel control unit 12 causes the automated guided vehicle 1 to travel in a state where the travel speed is further lower than the original travel speed for the section D where the difference between the actual travel distance and the reference travel distance is large in accordance with the limit speed amount set by the determination unit 15.

[0030] In the example of FIG. 4, the section D from the RFID tag 2 of No. 2 to the RFID tag of No. 4 is determined as the slip section Ds. In the section D, although the original traveling speed is 3.8 km / h, a speed limit of -0.5 km / h is applied, and the unmanned transport vehicle 1 travels at 3.3 km / h. Also, in the example of FIG. 4, the section D from the RFID tag 2 of No. 4 to the RFID tag 2 (not shown) of No. 5 is also determined as the slip section Ds. In the section D, although not shown, the difference between the actual traveling distance and the reference traveling distance with respect to the reference traveling distance is larger than that in the previous section D. Although the original traveling speed is 3.6 km / h, a speed limit of -0.7 km / h is applied, and the unmanned transport vehicle 1 travels at 2.9 km / h.

[0031] When a predetermined time has elapsed since the determination unit 15 determines the slip section Ds, for example, the determination of the slip section Ds in the section D may be canceled. The time until the determination of the slip section Ds is canceled may be input to the determination unit 15 together with the operation data W, for example, in the input operation of designating the route R for the unmanned transport vehicle 1.

[0032] Subsequently, the operation of the unmanned transport vehicle 1 described above will be described. FIG. 5 is a flowchart showing the determination control of the slip section Ds in the unmanned transport vehicle 1. Also, FIG. 6 is a flowchart showing the traveling control of a predetermined route R in the unmanned transport vehicle 1. The determination control of the slip section Ds and the traveling control of the route R shown in FIGS. 5 and 6 are performed for each section D of the route R. Also, the traveling control of the route R is performed in conjunction with the determination operation of the slip section Ds.

[0033] In the determination operation of the slip section Ds, as shown in FIG. 5, as the unmanned transport vehicle 1 travels along the route R, first, the RFID tag 2 is detected (step S01). Next, the operation data W is referred to based on the identification information of the detected RFID tag 2, and the unmanned transport vehicle 1 travels according to the operation specified in the operation data W (step S02).

[0034] When the driverless transport vehicle 1 further travels along the route R, the next RFID tag 2 is detected (step S03). When the next RFID tag 2 is detected, the actual travel distance in the section D is acquired (step S04). Then, a comparison is made between the actual travel distance and the reference travel distance in the section D (step S05), and it is determined whether the difference between the actual travel distance and the reference travel distance exceeds a predetermined threshold (step S06).

[0035] In step S06, if the difference between the actual travel distance and the reference travel distance is equal to or less than the predetermined threshold, the process ends without any special processing. In step S06, if the difference between the actual travel distance and the reference travel distance exceeds the predetermined threshold, it is determined that the section D is a slip section Ds (step S07). For the section D determined to be the slip section Ds, a speed limit value is set (step S08). The determination of the slip section Ds and the setting of the speed limit value are cancelled when a predetermined time has elapsed since the determination that the section D is the slip section Ds was made.

[0036] In the travel control of the route R, it is carried out in combination with the above-described determination operation of the slip section. As shown in FIG. 6, when the driverless transport vehicle 1 travels along the route R, first, the RFID tag 2 is detected (step S11). Next, the operation data W is referred to based on the identification information of the detected RFID tag 2 (step S12).

[0037] When referring to the operation data W, it is determined whether the section D is a slip section Ds (step S13). In step S13, if it is determined that the section D is not the slip section Ds, the travel control based on the operation data W is executed as it is (step S14). In step S13, if it is determined that the section D is the slip section Ds, the travel control based on the operation data W is executed in a state where the speed limit is taken into account (step S15). In either case of executing step S14 or step S15, when the driverless transport vehicle 1 further travels along the route R, the next RFID tag 2 is detected (step S16).

[0038] As described above, in the automated guided vehicle 1, based on the comparison between the actual traveled distance for each section D and the reference traveled distance, it is determined whether there is a slip section Ds in the section D on the route R. For the section D determined to be the slip section Ds, by restricting the traveling speed, it is possible to prevent the vehicle 1 from deviating from the route. This automated guided vehicle 1 has an actual traveled distance detection unit 14 that detects the actual traveled distance, and by holding in advance on the vehicle 1 side the reference traveled distance for each section D, it becomes possible to perform automatic travel control considering slip by the vehicle 1 itself. Since the vehicle 1 itself can acquire the data necessary for determining the slip section Ds, there is no need for a higher-level system or facility for acquiring data, and it is possible to avoid complication of the configuration and increase in manufacturing cost.

[0039] In the present embodiment, the travel control unit 12 increases the speed limit amount when traveling in the section D determined to be the slip section Ds as the difference between the actual traveled distance and the reference traveled distance is larger. By such control, it is possible to more reliably prevent the vehicle 1 from deviating from the route R when traveling in the slip section Ds.

[0040] In the present embodiment, when a predetermined time has elapsed since the determination unit 15 determines the section D as the slip section Ds, the determination of the slip section Ds in the section D is cancelled. Also, when canceling the determination of the slip section Ds, since it is not necessary to acquire data from a higher-level system or facility, it is possible to avoid complication of the configuration and increase in manufacturing cost.

[0041] The present disclosure is not limited to the above-described embodiment. For example, in the above-described embodiment, both the determination information indicating whether the section D is the slip section Ds and the restriction information indicating the speed limit amount in the slip section Ds are associated with the operation data W, but the determination information and the restriction information may be generated as data separate from the operation data W.

[0042] Also, in the above-described embodiment, when a predetermined time has elapsed since the determination unit 15 determines the slip section Ds, the determination of the slip section Ds in the section D is cancelled. However, when there is a higher-level system or facility, the higher-level system or facility may be used to cancel the determination of the slip section Ds. For example, precipitation information around the route R may be acquired from a higher-level system, and the determination of the slip section Ds may be cancelled when a certain time has elapsed after the precipitation amount has become zero.

[0043] In the above-described embodiment, a guided vehicle is exemplified as the unmanned transport vehicle 1. However, the present disclosure can also be applied to another guided unmanned transport vehicle using 3D-SLAM or the like. For an autonomous unmanned transport vehicle, a virtual RFID tag may be arranged on the route R instead of the RFID tag 2.

Explanation of reference numerals

[0044] 1... unmanned transport vehicle, 12... travel control unit, 14... actual travel distance detection unit (detection unit), D... section, Ds... slip section, R... route, W... operation data.

Claims

1. An automated guided vehicle that automatically travels along a predetermined path composed of a plurality of sections, a travel control unit that controls the vehicle's travel based on travel data indicating the operation of each section, a detection unit that detects the actual travel distance traveled by the vehicle on the road surface by the travel control unit, a determination unit that compares the actual travel distance with a reference travel distance for each section and determines a section where the difference between the actual travel distance and the reference travel distance exceeds a predetermined threshold as a slip section, and the travel control unit limits the travel speed when traveling through a section determined to be the slip section. An automated guided vehicle.

2. The automated guided vehicle according to claim 1, wherein the travel control unit increases the speed limit amount when traveling through a section determined to be the slip section as the difference between the actual travel distance and the reference travel distance increases.

3. The automated guided vehicle according to claim 1 or 2, wherein the determination unit cancels the determination of the slip section in the section when a predetermined time has elapsed since the time when the section was determined to be the slip section.

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