Article transport vehicle

Abstract

The invention provides an article transport vehicle. An article transport vehicle is provided with a holding unit for holding an article, a lifting device for lifting the holding unit, and a control device for controlling the lifting device. The lifting device includes a rotating body, a wound member wound around the rotating body, and a lifting drive motor that rotationally drives the rotating body. The control device is provided with: a transmission torque detection unit that detects a transmission torque between the rotating body and the lifting drive motor; and a weight estimation unit that estimates the weight of the article on the basis of the detected transmission torque.

Description

Technical Field

[0001] The invention relates to an article conveying vehicle. Background Art

[0002] An article transport vehicle for transporting articles is used. Japanese Patent Application Laid-Open No. 2020-200145 (Patent Document 1) discloses an example of such an article transport vehicle.

[0003] The article transport vehicle (crane 1) of Patent Document 1 includes a holding portion (claw 30) for holding an article (transport object), a lifting device (hoisting device 22) for raising and lowering the holding portion, and a control device (control unit 44) for controlling the lifting device. The lifting device includes a wound member (wire rope 23) that can be wound and unwound freely, and a lifting drive motor (motor 41) that rotates and drives a rotating body wound with the wound member. The control device monitors the torque of the lifting drive motor. Summary of the invention

[0004] In the article transport vehicle of Patent Document 1, the control device only monitors the torque of the lifting drive motor and stops the rotation of the lifting drive motor urgently when it detects that the motor torque exceeds a predetermined threshold value (threshold value L). That is, the technology disclosed in Patent Document 1 is a simple failure protection technology that only prevents the occurrence of abnormalities. However, it is preferable to use the torque of the lifting drive motor more actively and efficiently.

[0005] Therefore, it is hoped that the torque of the lifting drive motor can be used to efficiently operate the article transport vehicle.

[0006] The article transport vehicle disclosed in the present invention is an article transport vehicle for transporting articles; it is provided with a holding portion for holding the aforementioned article, a lifting device for raising and lowering the aforementioned holding portion, and a control device for controlling the aforementioned lifting device; the aforementioned lifting device is provided with a rotating body, a wound component that is wound around the aforementioned rotating body and can be wound up and unwound freely, and a lifting drive motor that rotationally drives the aforementioned rotating body, and is constructed so that, in a state where the aforementioned holding portion is suspended by the aforementioned wound component, the aforementioned holding portion is raised and lowered by means of the winding and unwinding of the aforementioned wound component brought about by rotating the aforementioned rotating body; the aforementioned control device is provided with: a transmission torque detection portion for detecting a transmission torque transmitted between the aforementioned rotating body and the aforementioned lifting drive motor; and a weight estimation portion for estimating the weight of the aforementioned article held by the aforementioned holding portion based on the aforementioned transmission torque detected by the aforementioned transmission torque detection portion.

[0007] According to this structure, the transmission torque transmitted between the rotating body and the lifting drive motor can be detected, and the weight of the article held by the holding portion can be estimated under various conditions based on the transmission torque. Moreover, the estimated result of the weight of the article obtained in this way can be used to realize the efficient operation of the article transport vehicle.

[0008] Further features and advantages of the technology disclosed herein will become more apparent from the following description of illustrative and non-limiting embodiments with reference to the accompanying drawings. BRIEF DESCRIPTION OF THE DRAWINGS

[0009] Figure 1 It is a side view of the article transport facility according to the first embodiment.

[0010] Figure 2 It is a side view of the article conveyor.

[0011] Figure 3 It is the front view of the goods conveyor vehicle.

[0012] Figure 4 It is a three-dimensional diagram of the lifting device.

[0013] Figure 5 It is the block diagram of the control system.

[0014] Figure 6 This is a flowchart showing the processing procedure of the fall-off determination process.

[0015] Figure 7 It is a time chart of the lifting speed of the holding part and the torque of the lifting drive motor.

[0016] Figure 8 It is a schematic diagram of a holding portion of an article transport vehicle according to a second embodiment.

[0017] Fig. 9 It is the block diagram of the control system.

[0018] Fig.10 This is a flowchart showing the processing procedure of the descent amount adjustment processing. DETAILED DESCRIPTION

[0019] [First embodiment]

[0020] The article transport vehicle according to the first embodiment will be described with reference to the accompanying drawings. The article transport vehicle 1 according to the present embodiment is used, for example, in a semiconductor manufacturing plant to transport articles 7. Figure 1 and Figure 2 As shown, the article transport vehicle 1 includes a traveling body 2, a holding unit 3, and a lifting device 4. In addition, the article transport vehicle 1 includes a control device 6 (see FIG. 6 ) for controlling the traveling body 2, the holding unit 3, and the lifting device 4. Figure 5 ).

[0021] The traveling body 2 travels along the travel path, and the holding portion 3 and the lifting device 4 are connected to the traveling body 2 in a state of being suspended from the traveling body 2 and supported. In this way, the entire article transport vehicle 1 travels along the travel path. In this embodiment, the travel path of the article transport vehicle 1 is physically formed by a track 92 suspended and supported from the ceiling 91. That is, the article transport vehicle 1 of this embodiment is a ceiling transport vehicle that moves along the track 92 formed along the ceiling 91.

[0022] The article 7 to be transported by the article transport vehicle 1 is not particularly limited, but examples thereof include a wafer storage container for storing wafers (so-called FOUP: Front Opening Unified Pod), a mask storage container for storing reticles (so-called mask box), and the like. Figure 2 As shown, the article 7 of the present embodiment includes a container body 71 and a flange 72 provided on the upper portion of the container body 71 .

[0023] The article transport vehicle 1 transports the article 7, for example, to a loading platform 96 of a processing device 95 provided below the travel path. The article transport vehicle 1 transfers the article 7 and lowers the article 7 by the lifting device 4 to carry the article 7 to a transfer target portion 97 (e.g., the upper surface) of the loading platform 96. In addition, the article transport vehicle 1 raises the article 7 by the lifting device 4 while holding the article 7 placed on the transfer target portion 97 of the loading platform 96, and carries the article 7 out of the transfer target portion 97. In addition, the height of the transfer target portion 97 may be the same at all positions or may be different for each position.

[0024] The traveling body 2 travels along a pair of rails 92. Figure 2 and Figure 3 As shown, the traveling body 2 includes a body 21, a traveling drive motor 22, wheels 23, and guide wheels 24. The body 21 supports the traveling drive motor 22, the wheels 23, and the guide wheels 24. The traveling drive motor 22 includes an electric motor such as a servo motor, and drives at least one wheel 23. The wheel 23 rolls on the upper surface of the track 92. The wheel 23 driven by the traveling drive motor 22 functions as a driving wheel. The guide wheel 24 rolls on the inner side of the track 92. The traveling body 2 travels on the track 92 in a state where the guide wheel 24 contacts the inner side of the track 92 and is guided.

[0025] In the following description, the direction in which the traveling body 2 travels, i.e., the direction along the extension direction of the rail 92, is referred to as the front-rear direction X of the article transport vehicle 1. In addition, the direction orthogonal to the front-rear direction X and along the arrangement direction of the pair of rails 92 is referred to as the left-right direction Y of the article transport vehicle 1. In addition, the direction orthogonal to both the front-rear direction X and the left-right direction Y is referred to as the up-down direction Z. In addition, these directions are directions based on the article transport vehicle 1, and the front-rear direction X and the left-right direction Y may differ depending on the position of the article transport vehicle 1 along the moving path when observed from a fixed point in the equipment. The up-down direction Z coincides with the vertical direction.

[0026] The holding part 3 and the lifting device 4 are arranged below the rail 92. The lifting device 4 is accommodated inside the cover body 50 suspended and supported from the traveling body 2. The holding part 3 is accommodated inside the cover body 50 in a state of being located at the upper limit position Pu of the lifting range. In addition, the cover body 50 has an upper cover part 51 covering the upper part and a pair of side cover parts 52 covering both sides in the front-rear direction X. The internal space of the cover body 50 is open on at least one side (both sides in this example) in the left-right direction Y.

[0027] The holding portion 3 is a portion for holding an article 7. Figure 2 and Figure 3 As shown, the holding portion 3 includes a connecting portion 31, an article supporting portion 32, and a holding drive motor 33 (see Figure 5 The connecting portion 31 is a portion connected to the lifting device 4, and in this embodiment, it also serves as a base (holding body) of the holding portion 3. The connecting portion 31 supports the article support portion 32 so that it can slide freely in the front-back direction X. In addition, the connecting portion 31 supports the holding drive motor 33 in a fixed manner.

[0028] The article support portion 32 contacts the article 7 and supports the article 7. The article support portion 32 of the present embodiment supports the flange 72 of the article 7 from below. In the present embodiment, a pair of article support portions 32 are provided so that the flange 72 of the article 7 can be supported from both sides in the front-rear direction X at the same time. The pair of article support portions 32 are arranged in the front-rear direction X while being spaced apart by a predetermined interval. Moreover, the pair of article support portions 32 are each configured to be slidable in the front-rear direction X, and move toward each other or away from each other along the front-rear direction X.

[0029] The holding drive motor 33 moves the pair of article supports 32 in the front-rear direction X. The holding drive motor 33 is connected to the pair of article supports 32 via a ball screw mechanism, for example. The holding drive motor 33 moves the pair of article supports 32 in opposite directions to move them closer to each other or away from each other along the front-rear direction X.

[0030] The lifting device 4 is a device for lifting the holding portion 3. Figure 4 As shown, the lifting device 4 includes a base 41, a rotating body 42, a wound component 43, a pulley 44, a lifting drive motor 45 and a transmission 46. The base 41 supports the rotating body 42, the pulley 44, the lifting drive motor 45 and the transmission 46. The rotating body 42 is rotatably supported by the base 41. In this embodiment, a plurality of (three in this example) rotating bodies 42 are coaxially arranged. The wound component 43 is wound around the rotating body 42 so as to be wound and unwound freely. The wound component 43 is guided downward by one or more pulleys 44 and is fixed at the lower end to the connecting portion 31 of the retaining portion 3, and the one or more pulleys 44 are rotatably supported by the base 41.

[0031] The lifting drive motor 45 is connected to the rotating body 42 via the transmission 46 so that the driving force can be transmitted. The lifting drive motor 45 drives the rotating body 42 to rotate so as to wind the winding member 43 on the rotating body 42 or unwind the winding member 43 from the rotating body 42. The transmission 46 is set as a speed reducer in this embodiment, and reduces the rotation of the lifting drive motor 45 and transmits it to the rotating body 42.

[0032] The lifting device 4 having such a structure lifts and lowers the holding portion 3 by winding and unwinding the wound member 43 due to the rotation of the rotating body 42 in a state where the holding portion 3 is suspended by the wound member 43 .

[0033] The control device 6 controls the movement of the article transport vehicle 1. The control device 6 controls the movement of the article transport vehicle 1 by controlling the travel body 2 (travel drive motor 22), the holding unit 3 (holding drive motor 33) and the lifting device 4 (lifting drive motor 45). The control device 6 is provided on the article transport vehicle 1, receives instructions from the upper control device 60 provided at the control facility not shown, and controls the movement of the article transport vehicle 1. In addition, the respective control devices 6 mounted on multiple article transport vehicles 1 can communicate with each other.

[0034] like Figure 5As shown in FIG. 1 , the control device 6 of the present embodiment includes a travel control unit 61, a transfer control unit 62, a transfer torque detection unit 63, a weight estimation unit 64, a recording unit 65, a monitoring unit 66, a fall-off determination unit 67, and an abnormality reporting unit 68. In addition, the control device 6 includes a CPU (Central Processing Unit) and other operation processing devices and RAM (Random Access Memory), ROM (Read Only Memory) and other main storage devices. Each functional unit of the control device 6 is realized by the cooperation of the operation processing unit and the program executed on the operation processing unit.

[0035] The travel control unit 61 controls the travel of the travel body 2. The travel control unit 61 controls the operation of the travel drive motor 22 to control the travel of the travel body 2 along the travel path.

[0036] The transfer control unit 62 controls the transfer of the article 7 using the holding unit 3. The transfer control unit 62 controls the operation of the holding drive motor 33 to control the support and release of the flange 72 of the article 7 by the pair of article support units 32. In addition, the transfer control unit 62 controls the operation of the lifting drive motor 45 to control the lifting of the holding unit 3. Furthermore, the transfer control unit 62 coordinately controls the operation of the holding drive motor 33 and the operation of the lifting drive motor 45 to control the transfer of the article 7.

[0037] The transmission torque detection unit 63 detects the transmission torque (hereinafter simply referred to as "transmission torque") transmitted between the rotating body 42 and the lifting drive motor 45. In the present embodiment, the transmission torque detection unit 63 detects the motor torque based on the motor current flowing in the lifting drive motor 45, and detects the transmission torque based on the obtained motor torque. In the structure in which the transmission 46 is interposed between the rotating body 42 and the lifting drive motor 45 as in the present embodiment, the transmission torque detection unit 63 detects the transmission torque as a value obtained by multiplying the motor torque by the gear ratio.

[0038] The timing of detecting the transmission torque is not particularly limited, but the transmission torque detection unit 63 preferably detects the transmission torque in the lifting stop state in which the lifting and lowering of the holding unit 3 by the lifting device 4 is stopped. In the lifting stop state, the motor current flowing in the lifting drive motor 45 is only the amount used to support the article 7, so there is less noise and the transmission torque can be detected with good accuracy.

[0039] For example, Figure 7In the example of , the transmission torque detection unit 63 preferably detects the transmission torque in the first period T1 or the second period T2 when the lifting speed of the holding unit 3 is "0 (zero)". Figure 7 In the figure, the positive value of the lifting speed of the holding part 3 indicates the descending speed, and the absolute value of the negative value indicates the ascending speed. The positive value of the torque of the lifting drive motor 45 indicates the torque in the direction of lowering the holding part 3, and the absolute value of the negative value indicates the torque in the direction of raising the holding part 3, respectively expressed as a percentage relative to the rated torque. The horizontal axis is time.

[0040] The first period T1 corresponds to a period during which the holding unit 3 is lowered to initially support the article 7 placed on the transfer target portion 97. In the first period T1, the holding unit 3 stops at the lower limit position Pd (see Figure 1 ). In addition, the lower limit position Pd of the lifting range of the holding portion 3 is determined according to the height of the transfer target portion 97. The second period T2 corresponds to the period during which the holding portion 3 holding the article 7 is raised again to stably support the article 7 in the cover body 50. In the second period T2, the holding portion 3 stops at the upper limit position Pu of the lifting range of the holding portion 3 (refer to Figure 1 ).

[0041] In addition, the position for detecting the transmission torque is not particularly limited, but the transmission torque detection unit 63 preferably detects the transmission torque when the holding unit 3 stops at the upper limit position Pu of the lifting range of the holding unit 3. When the holding unit 3 stops at the upper limit position Pu, the winding amount of the winding member 43 to the rotating body 42 becomes the maximum, and its radius becomes the maximum, so the transmission torque becomes large and the influence of noise becomes relatively small. As a result, the transmission torque can be detected with good accuracy.

[0042] The weight estimation unit 64 estimates the weight of the article 7 held by the holding unit 3 based on the transmission torque detected by the transmission torque detection unit 63. When the holding unit 3 holds the article 7 by the torque of the lifting drive motor 45, the following force balance is established in the wound member 43 wound on the rotating body 42.

[0043] (Transmission torque) = (radius of the taken-up member 43) × (force acting on the article 7) ... (A)

[0044] Here, the radius of the wound member 43 is determined by the sum of the radius of the rotating body 42 and the total thickness of the wound member 43 wound on the rotating body 42. In addition, the force acting on the article 7 is determined by the product of the weight of the article 7 and the gravitational acceleration. Therefore, the weight of the article 7 is calculated based on the above-mentioned formula (A) using the transmission torque detected by the transmission torque detection unit 63 and the radius of the wound member 43 as variables, so the weight estimation unit 64 estimates it as the weight of the article 7.

[0045] In addition, in the structure in which the transmission torque detection unit 63 detects the transmission torque when the holding unit 3 stops at the upper limit position Pu as in the present embodiment, the radius of the wound member 43 can also be regarded as a constant, so the weight estimation unit 64 can actually estimate the weight of the article 7 using only the transmission torque as a variable. The radius of the wound member 43 when the holding unit 3 stops at the upper limit position Pu can be obtained in advance by measurement and maintained as a predetermined value.

[0046] In addition, when the holding unit 3 is stopped at the upper limit position Pu, the article 7 is contained in the cover 50, and the article transport vehicle 1 may transport the article 7 in this state. In such a case, the vibration accompanying the travel of the article transport vehicle 1 (for example, the vibration caused by the step difference of the track 92, the vibration of the travel path such as the branching and merging, and the vibration caused by the wheels 23, the drive transmission system, etc. on the article transport vehicle 1 side) may have an adverse effect on the detection of the transmission torque and thus the estimation of the weight of the article 7. Therefore, the weight estimation unit 64 preferably estimates the weight of the article 7 based on the value obtained by applying a low-pass filter to the detection value of the transmission torque obtained by the transmission torque detection unit 63.

[0047] Before the article transport vehicle 1 (traveling body 2) starts traveling, the recording unit 65 records the weight of the article 7 estimated by the weight estimating unit 64 as the weight before traveling. The recording unit 65 ensures a temporary storage area in the main storage device of the control device 6, and records the weight before traveling in the temporary storage area.

[0048] The monitoring unit 66 continuously monitors the weight of the article 7 estimated by the weight estimating unit 64 while the article transport vehicle 1 (traveling body 2) is traveling. The monitoring unit 66 records the weight of the article 7 estimated by the weight estimating unit 64 in a temporary storage area in the main storage device of the control device 6 at a predetermined period.

[0049] The shedding determination unit 67 determines that at least a part of the article 7 has fallen off when the difference between the latest estimated weight of the article 7 grasped by the monitoring unit 66 and the weight before the start of the journey becomes greater than a predetermined determination threshold. The weight of the article 7 before the start of the journey and the latest estimated weight are both recorded in a temporary storage area in the main storage device of the control device 6. Based on them, the shedding determination unit 67 monitors the weight difference of the article 7 compared to before the start of the journey. The determination threshold can be set to a value slightly lighter than the weight of a part of the article 7 (such as the lid of the container, the contained object, etc.). When the weight difference of the article 7 before the start of the journey becomes greater than the determination threshold, the shedding determination unit 67 determines that at least a part of the article 7 has fallen off, and notifies the abnormality reporting unit 68 of the content.

[0050] When receiving a notification based on the fall-off determination from the fall-off determination unit 67, the abnormality reporting unit 68 reports that an abnormality has occurred in the article 7 being transported by the article transport vehicle 1. The abnormality reporting by the abnormality reporting unit 68 can be performed, for example, by displaying an abnormality on a monitor of a control computer, sounding a warning sound from a speaker, or the like.

[0051] The following describes the processing sequence of the fall-off determination process performed in the article transport vehicle 1 of this embodiment. In this embodiment, the transmission torque is detected at the upper limit position Pu and the weight of the article 7 is estimated. Figure 6 As shown, first, the holding part 3 holding the article 7 is raised (step #01). Then, it is determined whether the holding part 3 stops at the upper limit position Pu (#02). The holding part 3 continues to rise until it is determined to stop at the upper limit position Pu (#02: Yes).

[0052] When the holding portion 3 stops at the upper limit position Pu, the transmission torque transmitted between the rotating body 42 and the lifting drive motor 45 is detected by the transmission torque detection unit 63 (#03). In addition, based on the detected transmission torque, the weight of the article 7 held by the holding portion 3 is estimated by the weight estimation unit 64 (#04). In addition, the detection of the transmission torque and the estimation of the weight of the article 7 based on it are continuously performed at a predetermined cycle.

[0053] In the present embodiment, the recording unit 65 records the estimated weight of the article 7 and the value before the article transport vehicle 1 (traveling body 2) starts traveling as the weight before traveling (#05). Furthermore, after the article transport vehicle 1 (traveling body 2) starts traveling, the monitoring unit 66 also continuously records the estimated weight of the article 7 (#06). Then, based on the weight before traveling and the latest estimated weight of the article 7, the monitoring unit 66 continuously monitors the weight difference compared to the weight before traveling of the article transport vehicle 1 (traveling body 2) (#07).

[0054] The fall-off determination unit 67 determines whether the weight difference compared to the weight before the start of travel is greater than a predetermined determination threshold (#08). During the period when the weight difference is less than the determination threshold (#08: No), it is determined that no abnormality such as fall-off has occurred, and the monitoring of the weight difference continues. If the weight difference is greater than the determination threshold (#08: Yes), the fall-off determination unit 67 determines that at least a portion of the article 7 has fallen off (#09). In addition, the abnormality reporting unit 68 reports that an abnormality has occurred in the article 7 being transported (#10).

[0055] [Second embodiment]

[0056] The article transport vehicle of the second embodiment is described with reference to the accompanying drawings. The specific structure of the holding portion 3 of the article transport vehicle 1 of this embodiment is partially different from that of the first embodiment. In addition, along with this, the control content executed in the article transport vehicle 1 is also partially different from that of the first embodiment. Hereinafter, with respect to the article transport vehicle 1 of this embodiment, the differences from the first embodiment will be mainly described. In addition, for the points that are not particularly clearly described, they are the same as those of the first embodiment, and the same figure marks are given and detailed descriptions are omitted.

[0057] like Figure 8 As shown, the holding portion 3 of the article transport vehicle 1 of this embodiment includes a connecting portion 31, an article support portion 32, and a holding drive motor 33 (see Fig. 9 ), it is also provided with a support bracket 35 and an elastic support member 36. A pair of support brackets 35 are provided corresponding to the article support portion 32. The support brackets 35 are connected and fixed to the corresponding article support portion 32. The pair of support brackets 35 are arranged in the front-to-back direction X while being separated by a predetermined interval. Moreover, the pair of support brackets 35 are configured to slide freely in the front-to-back direction X together with the article support portion 32, and move toward each other or away from each other along the front-to-back direction X.

[0058] The elastic support member 36 is interposed between the connecting portion 31 and the support bracket 35 above the lower end surface of the connecting portion 31. The elastic support member 36 supports the article support portion 32 with respect to the connecting portion 31 in an elastic state in the up-down direction Z. By providing such an elastic support member 36, the vibration of the traveling body 2 caused by the traveling of the traveling body 2, the vibration of the holding portion 3 caused by the lifting of the lifting device 4, etc. can be attenuated. As a result, the article 7 can be stably supported in a state with less vibration, and the weight of the article 7 can be estimated with good accuracy. In the present embodiment, the elastic support member 36 is composed of a coil spring in a compressed state.

[0059] like Fig. 9 As shown, the control device 6 of the present embodiment includes a travel control unit 61 , a transfer control unit 62 , a transmission torque detection unit 63 , a weight estimation unit 64 , and a displacement estimation unit 69 .

[0060] The displacement estimating unit 69 estimates the displacement of the elastic supporting member 36 in the vertical direction Z based on the weight of the article 7 estimated by the weight estimating unit 64. In the present embodiment, the elastic supporting member 36 is provided between the connecting portion 31 and the supporting bracket 35 in a compressed state, and the displacement in the vertical direction Z is the compression amount. In addition, the displacement estimating unit 69 estimates the displacement in the vertical direction Z based on the size of the elastic supporting member 36 in the vertical direction Z when the holding portion 3 does not hold the article 7. The relationship between the weight of the article 7 and the displacement of the elastic supporting member 36 in the vertical direction Z is pre-stored, and the displacement estimating unit 69 substitutes the weight of the article 7 estimated by the weight estimating unit 64 into the relationship, and estimates the displacement of the elastic supporting member 36 in the vertical direction Z by calculation.

[0061] The displacement amount of the elastic support member 36 in the vertical direction Z estimated by the displacement amount estimating unit 69 is used when transferring the article 7. When the holding unit 3 is lowered while the article 7 is held by the holding unit 3 to transfer the article 7 to the transfer target portion 97, the transfer control unit 62 adjusts the amount of descent of the holding unit 3 caused by the lifting device 4 according to the displacement amount of the elastic support member 36 in the vertical direction Z estimated by the displacement amount estimating unit 69. More specifically, the transfer control unit 62 adjusts the amount of descent of the holding unit 3 caused by the lifting device 4 to decrease in response to an increase in the displacement amount of the elastic support member 36 in the vertical direction Z estimated by the displacement amount estimating unit 69.

[0062] The processing sequence of the descent adjustment process performed in the article transport vehicle 1 of this embodiment is described. In this embodiment, the transmission torque is detected and the weight of the article 7 is estimated at the upper limit position Pu. Fig.10 As shown, first, the holding part 3 holding the article 7 is raised (step #21). Then, it is determined whether the holding part 3 stops at the upper limit position Pu (#22). The holding part 3 continues to rise until it is determined to stop at the upper limit position Pu (#22: Yes).

[0063] When the holding portion 3 stops at the upper limit position Pu, the transmission torque detection unit 63 detects the transmission torque transmitted between the rotating body 42 and the lifting drive motor 45 (#23). In addition, based on the detected transmission torque, the weight estimation unit 64 estimates the weight of the article 7 held by the holding portion 3 (#24).

[0064] Furthermore, based on the estimated weight of the article 7, the displacement estimating unit 69 estimates the displacement of the elastic supporting member 36 in the vertical direction Z (#25). Based on the estimated displacement of the elastic supporting member 36, when the article 7 is transferred to the transfer target portion 97, the transfer control unit 62 adjusts the lowering amount of the holding unit 3 (#26).

[0065] [Other implementation methods]

[0066] (1) In the above-mentioned embodiments, the transmission torque detection unit 63 is mainly assumed to detect the transmission torque when the holding unit 3 stops at the upper limit position Pu or the lower limit position Pd of the lifting range of the holding unit 3. However, the present invention is not limited to such a structure, and the transmission torque detection unit 63 may detect the transmission torque when the holding unit 3 stops at any position between the upper limit position Pu and the lower limit position Pd. In such a case, the weight estimation unit 64 also estimates the weight of the article 7 using the radius of the winding member 43 as a variable.

[0067] (2) In the above-mentioned embodiments, the transmission torque detection unit 63 is described as an example in which the transmission torque is detected when the holding unit 3 is stopped. However, the present invention is not limited to such a structure, and the transmission torque detection unit 63 may detect the transmission torque when the holding unit 3 is raised and lowered at a constant speed by the lifting device 4. In such a case, the weight estimation unit 64 also estimates the weight of the article 7 using the radius of the taken-up member 43 as a variable.

[0068] (3) In the above-mentioned embodiments, the weight estimating unit 64 estimates the weight of the article 7 based on the value obtained by applying a low-pass filter to the detection value of the transmission torque obtained by the transmission torque detecting unit 63. However, the present invention is not limited to such a structure, and the weight estimating unit 64 may estimate the weight of the article 7 using the detection value of the transmission torque obtained by the transmission torque detecting unit 63 as it is (that is, without passing through the filter).

[0069] (4) In the first embodiment described above, the structure in which the determination threshold value that serves as a reference for the fall-off determination unit 67 to perform the fall-off determination is set to a specific value is described. However, the structure is not limited to such a structure, and the determination threshold value may be set separately to two or more values. For example, a first determination threshold value for performing the fall-off determination of only a part of the article 7 (for example, the cover) and a second determination threshold value that is larger than the first determination threshold value for performing the fall-off determination of the entire article 7 may be set.

[0070] (5) In the first embodiment described above, when the fall-off determination unit 67 determines that at least a portion of the article 7 has fallen off, only the abnormality reporting unit 68 reports that an abnormality has occurred in the conveyed article 7. However, the present invention is not limited to such a configuration, and in such a case, in addition to the abnormality reporting by the abnormality reporting unit 68, the travel control unit 61 may also immediately stop the travel of the travel body 2.

[0071] (6) In the second embodiment described above, the structure in which the elastic support member 36 is sandwiched between the connecting portion 31 and the support bracket 35 at a position above the lower end surface of the connecting portion 31 is described as an example. However, the present invention is not limited to such a structure, and the elastic support member 36 may be sandwiched between the connecting portion 31 and the support bracket 35 at a position below the connecting portion 31. In this case, the displacement amount of the elastic support member 36 in the vertical direction Z becomes the elongation amount.

[0072] (7) In each of the above-mentioned embodiments, the control device 6 may also include an overweight determination unit for determining whether the article 7 is overweight based on the weight estimated by the weight estimation unit 64. The overweight determination unit may, for example, determine that the article 7 is overweight when the estimated weight exceeds a predetermined maximum holding weight (which may also be a weight with a certain amount of margin added). When the overweight determination unit determines that the article 7 is overweight, the transfer control unit 62 may release the holding of the article 7 and the travel control unit 61 may stop the travel of the travel body 2. In the case of such an overweight determination, if the overweight determination is based on the use of Figure 7 By making a determination based on the estimated weight of the transmission torque detected in the first period T1 shown, it is possible to quickly determine whether there is an overload, which is preferable.

[0073] (8) In each of the above-mentioned embodiments, the transmission torque detection unit 63 detects the transmission torque based on the motor current flowing in the lifting drive motor 45. However, the present invention is not limited to such a structure, and for example, a torque sensor may be provided in the power transmission path between the rotating body 42 and the lifting drive motor 45, and the transmission torque detection unit 63 detects the transmission torque with the help of the torque sensor.

[0074] (9) The structures disclosed in the above-mentioned embodiments (including the above-mentioned embodiments and other embodiments; the same applies below) can also be combined with the structures disclosed in other embodiments and applied as long as there is no contradiction. Regarding other structures, the embodiments disclosed in this specification are also illustrative in all aspects and can be appropriately changed within the scope of the present disclosure.

[0075] [Summary of implementation methods]

[0076] To summarize the above, the article transport vehicle according to the present disclosure preferably has the following structures.

[0077] The lifting device is a lifting device for lifting and lowering the lifting device; the lifting device comprises a rotating body, a wound component that is wound around the rotating body and can be wound up and unwound freely, and a lifting drive motor that rotationally drives the rotating body, and is constructed so that the holding part is lifted and lowered by winding up and unwinding the wound component brought about by rotating the rotating body, while the holding part is suspended by the wound component; the control device comprises: a transmission torque detection unit that detects a transmission torque transmitted between the rotating body and the lifting drive motor; and a weight estimation unit that estimates the weight of the article held by the holding part based on the transmission torque detected by the transmission torque detection unit.

[0078] According to this structure, the transmission torque transmitted between the rotating body and the lifting drive motor can be detected, and the weight of the article held by the holding portion can be estimated under various conditions based on the transmission torque. Moreover, the estimated result of the weight of the article obtained in this way can be used to realize the efficient operation of the article transport vehicle.

[0079] As one embodiment, the transmission torque detection unit preferably detects the transmission torque in a lifting stop state in which lifting and lowering of the holding unit by the lifting device is stopped or in a constant speed lifting and lowering state in which the holding unit is lifted and lowered at a constant speed by the lifting and lowering device.

[0080] According to this configuration, since the transmission torque is detected in a state where the acceleration due to the lifting and lowering movement of the holding portion by the lifting device does not act on the article, it is easy to improve the accuracy of weight estimation.

[0081] As one aspect, it is preferable that the transmission torque detection unit detects the transmission torque in a state where the holding unit is stopped at an upper limit position of a lifting range of the holding unit.

[0082] In many cases, when the holding portion is at the upper limit position of the lifting range, the amount of the wound component wound onto the rotating body is large. Moreover, as the length of the wound component wound onto the rotating body increases, the outer diameter of the wound component wound onto the rotating body increases, and the torque required to support the article increases proportionally. Therefore, by detecting the transmission torque in the state of stopping at the upper limit position of the lifting range as described above, the detection error can be relatively reduced, thereby improving the accuracy of weight estimation, compared with, for example, detecting the transmission torque in the state of stopping at the lower limit position of the lifting range.

[0083] As one embodiment, it is preferred that the vehicle further comprises a traveling body connected to the aforementioned holding portion and the aforementioned lifting device and traveling along a traveling path; the aforementioned control device further comprises: a recording portion, which records the weight of the aforementioned article estimated by the aforementioned weight estimating portion as a weight before the travel starts, before the aforementioned traveling body starts traveling; a monitoring portion, which continuously monitors the weight of the aforementioned article estimated by the aforementioned weight estimating portion during the travel of the aforementioned traveling body; and a shedding determination portion, which determines that at least a portion of the aforementioned article has fallen off, when the difference between the latest estimated weight of the aforementioned article grasped by the aforementioned monitoring portion and the aforementioned weight before the travel starts becomes greater than a predetermined determination threshold.

[0084] According to this structure, even if the article transport vehicle is not provided with a fall-off detection sensor, it is possible to continuously monitor the estimated result of the weight of the article based on the detected transmission torque and detect when at least a part of the article has fallen off. Thus, the article transport vehicle can be provided with a fall-off detection function while achieving a simplified structure and reduced costs.

[0085] As one aspect, it is preferable that the weight estimating unit estimates the weight of the article based on a value obtained by applying a low-pass filter to a detection value of the transfer torque obtained by the transfer torque detecting unit.

[0086] According to this configuration, the high-frequency components of the vibration of the article transport vehicle caused by the structure of the article transport vehicle, the state of the travel path, etc. can be reduced to suppress the fluctuation of the estimated value of the article weight. This makes it easy to improve the accuracy of the article drop determination.

[0087] As one embodiment, it is preferred that the holding portion comprises an article supporting portion which contacts the article to support the article, a connecting portion connected to the lifting device, and an elastic supporting member which supports the article supporting portion in an elastic state in the up and down directions relative to the connecting portion; the control device further comprises a displacement estimating portion which estimates the displacement of the elastic supporting member in the up and down directions based on the weight of the article estimated by the weight estimating portion.

[0088] According to this configuration, when the holding portion includes an elastic support member, the displacement of the elastic support member in the vertical direction caused by the weight of the article can be estimated. Thus, the change in the position of the article in the vertical direction caused by the change in the displacement of the elastic support member can be appropriately estimated.

[0089] As one method, it is preferred that when the control device lowers the holding portion while the article is held by the holding portion to transfer the article to the transfer object portion, the control device adjusts the amount of descent of the holding portion brought about by the lifting device to reduce the amount of descent in response to an increase in the estimated displacement estimated by the displacement amount estimating portion.

[0090] According to this configuration, even when the displacement amount of the elastic support member varies for each article due to the weight of each article, the article can be lowered to an appropriate height relative to the transfer target site by appropriately adjusting the lowering amount of the holding portion.

[0091] The article transport vehicle according to the present disclosure only needs to be able to achieve at least one of the above-mentioned effects.

[0092] Description of Reference Numerals

[0093] 1 Goods transport vehicle

[0094] 2. Driving body

[0095] 3. Holding part

[0096] 4 Lifting device

[0097] 6 Control device

[0098] 7 Items

[0099] 22 Travel drive motor

[0100] 31 Connection

[0101] 32. Article support

[0102] 36 Elastic support member

[0103] 42 Rotating body

[0104] 43. Reeled Parts

[0105] 45 Lifting drive motor

[0106] 63 Transmission torque detection unit

[0107] 64 Weight estimation unit

[0108] 65 Records Department

[0109] 66 Surveillance Department

[0110] 67 Falling off judgment unit

[0111] 68 Abnormal Reporting Department

[0112] 69 Displacement estimation unit

[0113] 97 Transfer target area

[0114] Pu upper limit position

Claims

1. An article transport vehicle is an article transport vehicle for transporting articles, characterized in that: A holding portion for holding the article, a lifting device for lifting the holding portion, and a control device for controlling the lifting device; The lifting device comprises a rotating body, a taken-up member which is wound around the rotating body and can be wound up and unwound freely, and a lifting drive motor which rotationally drives the rotating body, and is configured to lift the holding portion by winding up and unwinding the taken-up member caused by rotating the rotating body, while the holding portion is suspended by the taken-up member. The aforementioned control device comprises: a transmission torque detection unit for detecting a transmission torque transmitted between the rotating body and the lifting drive motor; and The weight estimating unit estimates the weight of the article held by the holding unit based on the transmission torque detected by the transmission torque detecting unit.

2. The article transport vehicle according to claim 1, characterized in that: The transmission torque detection unit detects the transmission torque in a lifting stop state in which the lifting device stops lifting the holding unit or in a constant speed lifting state in which the lifting device lifts the holding unit at a constant speed.

3. The article transport vehicle according to claim 1, characterized in that: The transfer torque detection unit detects the transfer torque in a state where the holding unit is stopped at an upper limit position of a lifting range of the holding unit.

4. The article transport vehicle according to any one of claims 1 to 3, characterized in that: A travel body connected to the holding portion and the lifting device and traveling along the travel path is also provided; The aforementioned control device also has: a recording unit that records the weight of the article estimated by the weight estimating unit as a weight before the traveling body starts traveling; a monitoring unit that continuously monitors the weight of the article estimated by the weight estimating unit during travel of the traveling body; and The fall-off determination unit determines that at least a part of the article has fallen off when a difference between a latest estimated weight of the article grasped by the monitoring unit and the weight before the start of traveling is equal to or larger than a predetermined determination threshold.

5. The article transport vehicle according to claim 4, characterized in that: The weight estimating unit estimates the weight of the article based on a value obtained by applying a low-pass filter to a detection value of the transfer torque obtained by the transfer torque detecting unit.

6. The article transport vehicle according to any one of claims 1 to 3, characterized in that: The holding portion includes an article support portion that contacts the article to support the article, a connection portion that is connected to the lifting device, and an elastic support member that supports the article support portion in a state of elasticity in the vertical direction relative to the connection portion; The control device further includes a displacement amount estimating unit that estimates the displacement amount of the elastic supporting member in the up-down direction based on the weight of the article estimated by the weight estimating unit.

7. The article transport vehicle according to claim 6, characterized in that: When the control device lowers the holding portion while the article is held by the holding portion to transfer the article to the transfer target portion, the control device adjusts the amount of descent of the holding portion brought about by the lifting device to reduce the amount of descent as the estimated displacement estimated by the displacement amount estimating portion increases.

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