Goods transport vehicle

Abstract

To efficiently operate the goods transport vehicle using the torque of the lift drive motor.SOLUTION: The goods transport vehicle includes: a holding section that retains goods; a lifting device that raises and lowers the holding section; and a control device (6) that controls the lifting device. The lifting device includes: a rotating body; a winding member wrapped around the rotating body; and a lifting drive motor (45) that drives the rotation of the rotating body. The control device (6) includes: a transmission torque detection section (63) that detects the transmission torque between the rotating body and the lifting drive motor (45); and a weight estimation section (64) that estimates the weight of the goods based on the detected transmission torque.SELECTED DRAWING: Figure 5

Description

[Technical field]

[0001] The present invention relates to an article transport vehicle. [Background technology]

[0002] Article transport vehicles that transport articles are used. One example of such an article transport vehicle is disclosed in JP 2020-200145 A (Patent Document 1).

[0003] The article transport vehicle (crane 1) of Patent Document 1 comprises a holding section (claw 30) that holds an article (object to be transported), a lifting device (hoisting device 22) that raises and lowers the holding section, and a control device (control unit 44) that controls the lifting device. The lifting device comprises a wound member (wire rope 23) that is wound so as to be freely wound and unwound, and a lifting drive motor (motor 41) that rotates and drives the rotor around which the wound member is wound. The control device monitors the torque of the lifting drive motor. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] JP 2020-200145 A Summary of the Invention [Problem to be solved by the invention]

[0005] In the article transport vehicle of Patent Document 1, the control device monitors the torque of the lift drive motor, and when it detects that the motor torque has exceeded a predetermined threshold (threshold L), it simply brings the lift drive motor to an emergency stop. In other words, the technology disclosed in Patent Document 1 is simply a fail-safe technology that prevents abnormalities from occurring. However, it would be preferable to use the torque of the lift drive motor to operate the article transport vehicle more actively and efficiently.

[0006] It is therefore desirable to be able to operate the article transport vehicle efficiently using the torque of the lift drive motor. [Means for solving the problem]

[0007] The article transport vehicle according to the present disclosure includes: An article transport vehicle for transporting articles, The apparatus includes a holding unit that holds the article, a lifting device that lifts and lowers the holding unit, and a control device that controls the lifting device, The lifting device includes a rotating body, a wound member wound around the rotating body so as to be freely wound and unwound, and a lifting drive motor that rotates the rotating body, and is configured to lift and lower the holding part by winding and unwinding the wound member by rotating the rotating body while the holding part is suspended by the wound member, The control device includes: a transmission torque detection unit that detects a transmission torque transmitted between the rotating body and the lift drive motor; a weight estimation unit that estimates a weight of the item held by the holding unit based on the transmission torque detected by the transmission torque detection unit; Equipped with.

[0008] According to this configuration, the weight of the article held by the holder can be estimated under various conditions based on the transmitted torque detected between the rotor and the lift drive motor, and the estimated weight of the article thus obtained can be used to efficiently operate the article transport vehicle.

[0009] Further features and advantages of the techniques disclosed herein will become more apparent from the following description of exemplary and non-limiting embodiments, which proceeds with reference to the drawings. [Brief description of the drawings]

[0010] [Figure 1] 1 is a side view of an article transport facility according to a first embodiment; [Diagram 2] Side view of goods transport vehicle [Diagram 3] Front view of goods transport vehicle [Figure 4] Perspective view of the lifting device [Diagram 5] Control system block diagram [Figure 6] A flowchart showing the procedure of the dropout determination process. [Figure 7] Time chart of lifting speed of holding unit and torque of lifting drive motor [Figure 8] Schematic diagram of a holding portion of an article transport vehicle according to a second embodiment. [Figure 9] Control system block diagram [Figure 10] A flowchart showing the procedure for the lowering amount adjustment process. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0011] [First embodiment] An article transport vehicle of a first embodiment will be described with reference to the drawings. An article transport vehicle 1 of this embodiment is used to transport an article 7, for example, in a semiconductor manufacturing factory or the like. As shown in Figs. 1 and 2, the article transport vehicle 1 includes a running body 2, a holding unit 3, and a lifting device 4. The article transport vehicle 1 also includes a control device 6 (see Fig. 5) that controls the running body 2, the holding unit 3, and the lifting device 4.

[0012] The running body 2 runs along a running path, and the holding unit 3 and the lifting device 4 are connected to the running body 2 while being suspended from the running body 2. In this way, the entire article transport vehicle 1 runs along the running path. In this embodiment, the running path of the article transport vehicle 1 is physically formed by rails 92 suspended from a ceiling 91. In other words, the article transport vehicle 1 of this embodiment is a ceiling transport vehicle that moves along rails 92 formed along the ceiling 91.

[0013] The article 7, which is an object to be transported by the article transport vehicle 1, is not particularly limited, but examples include containers such as a wafer storage container (so-called FOUP: Front Opening Unified Pod) that stores wafers, and a reticle storage container (so-called reticle pod) that stores reticles. As shown in Fig. 2, the article 7 in this embodiment has a container body 71 and a flange 72 provided on the upper part of the container body 71.

[0014] The article transport vehicle 1 transports the article 7 to a loading platform 96 of a processing device 95 installed, for example, below the travel path. While transporting the article 7, the article transport vehicle 1 lowers the article 7 using the lifting device 4, and transports the article 7 to a transfer target location 97 (for example, the upper surface) of the loading platform 96. The article transport vehicle 1 also lifts the article 7 using the lifting device 4 while holding the article 7 placed on the transfer target location 97 of the loading platform 96, and transports the article 7 out of the transfer target location 97. The height of the transfer target location 97 may be the same at all positions, or may be different for each position.

[0015] The traveling body 2 travels along a pair of rails 92. As shown in Figs. 2 and 3, the traveling body 2 includes a vehicle body 21, a traveling drive motor 22, wheels 23, and guide wheels 24. The vehicle body 21 supports the traveling drive motor 22, the wheels 23, the guide wheels 24, and the like. 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 rails 92. The wheel 23 drivingly connected to the traveling drive motor 22 functions as a drive wheel. The guide wheel 24 rolls on the inner surface of the rails 92. The traveling body 2 travels along the rails 92 with the guide wheel 24 in contact with and guided by the inner surface of the rail 92.

[0016] In the following description, the direction along the extension direction of the rails 92, which is the direction in which the traveling body 2 travels, is referred to as the forward / rearward direction X of the article transport vehicle 1. Additionally, the direction perpendicular to the forward / rearward 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. Additionally, the direction perpendicular to both the forward / rearward direction X and the left / right direction Y is referred to as the up / down direction Z. Note that each of these directions is based on the article transport vehicle 1, and the forward / rearward direction X and the left / right direction Y may differ depending on the position of the article transport vehicle 1 along the travel path when viewed from a fixed point in the facility. The up / down direction Z coincides with the vertical direction.

[0017] The holding unit 3 and the lifting device 4 are disposed below the rail 92. The lifting device 4 is housed inside a cover body 50 suspended from the traveling body 2. The holding unit 3 is housed inside the cover body 50 in a state where it is located at an upper limit position Pu of the lifting range. The cover body 50 has an upper cover part 51 that covers the upper side, and a pair of side cover parts 52 that cover 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.

[0018] The holder 3 is a portion for holding an article 7. As shown in Figs. 2 and 3, the holder 3 has a connecting portion 31, an article support portion 32, and a holding drive motor 33 (see Fig. 5). The connecting portion 31 is a portion connected to the lifting device 4, and in this embodiment, also serves as a base (holding main body portion) of the holder 3. The connecting portion 31 supports the article support portion 32 so that it can slide freely in the front-rear direction X. The connecting portion 31 also supports the holding drive motor 33 in a fixed manner.

[0019] The article support part 32 contacts the article 7 and supports the article 7. The article support part 32 in this embodiment supports the flange 72 of the article 7 from below. In this embodiment, a pair of article support parts 32 is provided so as to simultaneously support the flange 72 of the article 7 from both sides in the front-rear direction X. The pair of article support parts 32 are provided side by side in the front-rear direction X with a predetermined gap between them. The pair of article support parts 32 are each configured to be slidable in the front-rear direction X, and move toward or away from each other along the front-rear direction X.

[0020] The holding drive motor 33 moves the pair of article support parts 32 in the front-rear direction X. The holding drive motor 33 is connected to the pair of article support parts 32 via, for example, a ball screw mechanism. The holding drive motor 33 moves the pair of article support parts 32 in opposite directions to each other so as to move closer to each other or move away from each other along the front-rear direction X.

[0021] The lifting device 4 is a device for lifting and lowering the holding unit 3. As shown in FIG. 4, the lifting device 4 includes a base 41, a rotating body 42, a wound member 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 rotating bodies 42 (three in this example) are coaxially arranged. The wound member 43 is wound around the rotating body 42 so as to be freely wound up and unwound. The wound member 43 is guided downward by one or more pulleys 44 rotatably supported by the base 41, and is fixed at its lower end to the connecting portion 31 of the holding unit 3.

[0022] The lift drive motor 45 is connected to the rotating body 42 via a transmission 46 so as to be able to transmit a driving force to the rotating body 42. The lift drive motor 45 drives the rotating body 42 to rotate so as to wind the wound member 43 onto the rotating body 42 or to unwind the wound member 43 from the rotating body 42. The transmission 46 is a reducer in this embodiment, and transmits the rotation of the lift drive motor 45 to the rotating body 42 after reducing the speed.

[0023] The lifting device 4 configured as described above lifts and lowers the holding unit 3 by rotating the rotor 42 to wind and unwind the wound member 43 while the holding unit 3 is suspended by the wound member 43.

[0024] The control device 6 controls the operation of the article transport vehicle 1. The control device 6 controls the operation of the article transport vehicle 1 by controlling the running body 2 (running 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, and controls the operation of the article transport vehicle 1 upon receiving commands from a higher-level control device 60 installed in a control facility not shown. Note that the control devices 6 installed on each of multiple article transport vehicles 1 may be able to communicate with each other.

[0025] 5, the control device 6 of this embodiment includes a travel control unit 61, a transfer control unit 62, a transmission torque detection unit 63, a weight estimation unit 64, a recording unit 65, a monitoring unit 66, a dropout determination unit 67, and an abnormality reporting unit 68. The control device 6 also includes an arithmetic processing device such as a CPU (Central Processing Unit), and a main storage device such as a RAM (Random Access Memory) or a ROM (Read Only Memory). Each functional unit of the control device 6 is realized by cooperation between the arithmetic processing device and a program executed on the arithmetic processing device.

[0026] The travel control unit 61 controls the travel of the traveling body 2. The travel control unit 61 controls the operation of the travel drive motor 22 to control the travel of the traveling body 2 along the travel route.

[0027] 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 supporting and releasing of the flange 72 of the article 7 by the pair of article support units 32. The transfer control unit 62 also controls the operation of the lifting drive motor 45 to control the lifting and lowering of the holding unit 3. The transfer control unit 62 then controls the operation of the holding drive motor 33 and the operation of the lifting drive motor 45 in a coordinated manner to control the transfer of the article 7.

[0028] 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 lift drive motor 45. In this embodiment, the transmission torque detection unit 63 detects the motor torque based on the motor current flowing through the lift drive motor 45, and detects the transmission torque based on the obtained motor torque. In a configuration in which the transmission 46 is interposed between the rotating body 42 and the lift drive motor 45 as in this embodiment, the transmission torque detection unit 63 detects the transmission torque as a value obtained by multiplying the motor torque by the gear ratio.

[0029] Although there is no particular limitation on the timing for detecting the transmitted torque, it is preferable that the transmitted torque detection unit 63 detects the transmitted torque in a lift-and-lower state in which the lifting device 4 stops lifting and lowering the holding unit 3. In the lift-and-lower state, the motor current flowing through the lift drive motor 45 is only that required to support the article 7, so there is little noise and the transmitted torque can be detected with high accuracy.

[0030] For example, in the example of Fig. 7, it is preferable that the transmission torque detection unit 63 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)". In Fig. 7, the lifting speed of the holding unit 3 is such that a positive value indicates a descending speed, and an absolute negative value indicates an ascending speed. The torque of the lift drive motor 45 is expressed as a percentage of the rated torque, with a positive value indicating a torque in a direction that lowers the holding unit 3, and an absolute negative value indicating a torque in a direction that raises the holding unit 3. The horizontal axis is time.

[0031] The first period T1 corresponds to the period during which the holding unit 3 is lowered to initially support the item 7 placed on the transfer target location 97. In the first period T1, the holding unit 3 is stopped at the lower limit position Pd (see FIG. 1) of the lifting range of the holding unit 3. The lower limit position Pd of the lifting range of the holding unit 3 is determined according to the height of the transfer target location 97. The second period T2 corresponds to the period during which the holding unit 3 holding the item 7 is raised again to stably support the item 7 within the cover body 50. In the second period T2, the holding unit 3 is stopped at the upper limit position Pu (see FIG. 1) of the lifting range of the holding unit 3.

[0032] In addition, the position at which the transmission torque is detected is not particularly limited, but it is preferable that the transmission torque detection unit 63 detects the transmission torque in a state where the holding unit 3 is stopped at the upper limit position Pu of the elevation range of the holding unit 3. When the holding unit 3 is stopped at the upper limit position Pu, the amount of the take-up member 43 wound around the rotating body 42 is maximized, and the radius of the take-up member 43 is maximized, so that the transmission torque is large and the influence of noise is relatively small. Therefore, the transmission torque can be detected with high accuracy.

[0033] 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 lift drive motor 45, the following force balance is established in the wound member 43 wound around the rotating body 42. (Transmission torque)=(Radius of the wound member 43)×(Force acting on the article 7) (A)

[0034] 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 around the rotating body 42. The force acting on the article 7 is determined by the product of the weight of the article 7 and the acceleration of gravity. Therefore, the weight of the article 7 is calculated based on the above formula (A) using the transmitted torque detected by the transmitted torque detection unit 63 and the radius of the wound member 43 as variables, and the weight estimation unit 64 estimates this as the weight of the article 7.

[0035] In a configuration in which the transmission torque detection unit 63 detects the transmission torque while the holding unit 3 is stopped at the upper limit position Pu as in this embodiment, the radius of the wound member 43 can also be regarded as a constant, so the weight estimation unit 64 can essentially estimate the weight of the article 7 using only the transmission torque as a variable. The radius of the wound member 43 while the holding unit 3 is stopped at the upper limit position Pu is preferably obtained by measurement in advance and stored as a specified value.

[0036] Incidentally, when the holder 3 is stopped at the upper limit position Pu, the article 7 is contained within the cover body 50, and the article transport vehicle 1 may transport the article 7 in this state. In such a case, vibrations accompanying the travel of the article transport vehicle 1 (for example, vibrations caused by the travel path such as steps on the rail 92 or junctions, or vibrations caused by the article transport vehicle 1 side such as the wheels 23 and the drive transmission system) may adversely affect the detection of the transmission torque and, in turn, the estimation of the weight of the article 7. Therefore, it is preferable that the weight estimation unit 64 estimates the weight of the article 7 based on a value obtained by applying a low-pass filter to the detection value of the transmission torque obtained by the transmission torque detection unit 63.

[0037] 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 estimation unit 64 as the pre-travel weight. The recording unit 65 secures a temporary storage area in the main storage device of the control device 6, and records the pre-travel weight in the temporary storage area.

[0038] The monitoring unit 66 continuously monitors the weight of the item 7 estimated by the weight estimation unit 64 while the item transport vehicle 1 (traveling body 2) is traveling. The monitoring unit 66 records the weight of the item 7 estimated by the weight estimation unit 64 in a temporary storage area secured in the main storage device of the control device 6 at a predetermined period.

[0039] The detachment determination unit 67 determines that at least a part of the item 7 has fallen off when the difference between the latest estimated weight of the item 7 grasped by the monitoring unit 66 and the weight before the start of travel is equal to or greater than a predetermined determination threshold. The weight of the item 7 before the start of travel 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 these, the detachment determination unit 67 monitors the difference in weight of the item 7 from before the start of travel. The determination threshold can be set to a value slightly lighter than the weight of a part of the item 7 (e.g., a container lid or contents, etc.), for example. When the difference in weight of the item 7 from before the start of travel is equal to or greater than the determination threshold, the detachment determination unit 67 determines that at least a part of the item 7 has fallen off, and notifies the abnormality reporting unit 68 of that effect.

[0040] When the abnormality reporting unit 68 receives a notification of the detachment determination from the detachment determination unit 67, it reports that an abnormality has occurred with the item 7 being transported by the item transport vehicle 1. The abnormality reporting unit 68 can report the abnormality, for example, by displaying the abnormality on the monitor of the control computer or by sounding an alarm from a speaker.

[0041] The procedure of the falling-off determination process executed in the article transport vehicle 1 of this embodiment will be described. In this embodiment, the detection of the transmission torque and the estimation of the weight of the article 7 are configured to be performed at the upper limit position Pu, and as shown in Fig. 6, first, the holding unit 3 holding the article 7 is raised (step #01). Then, it is determined whether the holding unit 3 is stopped at the upper limit position Pu (#02). The raising of the holding unit 3 continues until it is determined that it has stopped at the upper limit position Pu (#02: Yes).

[0042] With the holder 3 stopped at the upper limit position Pu, the transmission torque detector 63 detects the transmission torque transmitted between the rotor 42 and the lift drive motor 45 (#03). Based on the detected transmission torque, the weight estimator 64 estimates the weight of the article 7 held by the holder 3 (#04). The detection of the transmission torque and the estimation of the weight of the article 7 based thereon are continuously performed at a predetermined cycle.

[0043] In this embodiment, the estimated weight of the item 7 before the item transport vehicle 1 (running body 2) starts running is recorded by the recording unit 65 as the pre-run weight (#05). In addition, even after the item transport vehicle 1 (running body 2) starts running, the monitoring unit 66 continues to record the estimated weight of the item 7 (#06). Then, based on the pre-run weight and the latest estimated weight of the item 7, the monitoring unit 66 continues to monitor the weight difference from before the item transport vehicle 1 (running body 2) started running (#07).

[0044] The detachment determination unit 67 determines whether the weight difference from before the start of travel has reached or exceeded a predetermined determination threshold (#08). As long as the weight difference is less than the determination threshold (#08: No), it is determined that no abnormality such as detachment has occurred, and monitoring of the weight difference continues. When the weight difference reaches or exceeds the determination threshold (#08: Yes), the detachment determination unit 67 determines that at least a portion of the item 7 has fallen off (#09). In addition, the abnormality reporting unit 68 reports that an abnormality has occurred with the item 7 being transported (#10).

[0045] Second Embodiment An article transport vehicle of the second embodiment will be described with reference to the drawings. The specific configuration of the holding section 3 of the article transport vehicle 1 of this embodiment is partially different from that of the first embodiment. Accordingly, the control contents executed in the article transport vehicle 1 are also partially different from that of the first embodiment. Below, the article transport vehicle 1 of this embodiment will be described, focusing mainly on the differences from the first embodiment. Note that points that are not specifically mentioned are the same as those of the first embodiment, and the same reference numerals will be used to omit detailed explanations.

[0046] As shown in Fig. 8, the holding section 3 of the article transport vehicle 1 of this embodiment further includes a support bracket 35 and an elastic support member 36 in addition to a connecting section 31, an article support section 32, and a holding drive motor 33 (see Fig. 9). A pair of support brackets 35 are provided corresponding to the article support sections 32. The support brackets 35 are connected and fixed to the corresponding article support sections 32. The pair of support brackets 35 are provided side by side in the front-rear direction X with a predetermined gap between them. The pair of support brackets 35 are configured to be slidable in the front-rear direction X together with the article support sections 32, and move toward or away from each other along the front-rear direction X.

[0047] The elastic support member 36 is interposed between the connecting part 31 and the support bracket 35, above the lower end surface of the connecting part 31. The elastic support member 36 supports the article support part 32 in a state of elasticity in the vertical direction Z with respect to the connecting part 31. By providing such an elastic support member 36, it is possible to attenuate vibrations of the running body 2 caused by the running of the running body 2, and vibrations of the holding part 3 caused by the lifting device 4 being raised and lowered, etc. Therefore, the article 7 can be stably supported with little vibration, and the weight of the article 7 can be accurately estimated. In this embodiment, the elastic support member 36 is configured of a coil spring in a compressed state.

[0048] As shown in FIG. 9, the control device 6 of this 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 amount estimation unit 69.

[0049] The displacement amount estimation unit 69 estimates the displacement amount in the vertical direction Z of the elastic support member 36 based on the weight of the article 7 estimated by the weight estimation unit 64. In the present embodiment, the elastic support member 36 is provided in a compressed state between the connecting portion 31 and the support bracket 35, and the displacement amount in the vertical direction Z is the compression amount. Further, the displacement amount estimation unit 69 estimates the displacement amount in the vertical direction Z with reference to the dimension in the vertical direction Z of the elastic support member 36 in a state where the holding portion 3 does not hold the article 7. The relationship between the weight of the article 7 and the displacement amount in the vertical direction Z of the elastic support member 36 is stored in advance, and the displacement amount estimation unit 69 substitutes the weight of the article 7 estimated by the weight estimation unit 64 into the relational expression, and estimates the displacement amount in the vertical direction Z of the elastic support member 36 by calculation.

[0050] The displacement amount in the vertical direction Z of the elastic support member 36 estimated by the displacement amount estimation unit 69 is used when transferring the article 7. When the holding portion 3 is lowered to transfer the article 7 to the transfer target location 97 while the article 7 is held by the holding portion 3, the transfer control unit 62 adjusts the lowering amount of the holding portion 3 by the lifting device 4 according to the displacement amount in the vertical direction Z of the elastic support member 36 estimated by the displacement amount estimation unit 69. More specifically, the transfer control unit 62 adjusts so as to reduce the lowering amount of the holding portion 3 by the lifting device 4 as the displacement amount in the vertical direction Z of the elastic support member 36 estimated by the displacement amount estimation unit 69 increases.

[0051] The processing procedure of the lowering amount adjustment process executed in the article carrier 1 of the present embodiment will be described. Also in the present embodiment, the detection of the transmission torque and the estimation of the weight of the article 7 are performed at the upper limit position Pu. As shown in FIG. 10, first, the holding portion 3 holding the article 7 is raised (step #21). Then, it is determined whether or not the holding portion 3 has stopped at the upper limit position Pu (#22). The raising of the holding portion 3 is continued until it is determined that the holding portion 3 has stopped at the upper limit position Pu (#22: Yes).

[0052] With the holder 3 stopped at the upper limit position Pu, the transmission torque detector 63 detects the transmission torque transmitted between the rotor 42 and the lift drive motor 45 (#23). Furthermore, based on the detected transmission torque, the weight estimator 64 estimates the weight of the article 7 held by the holder 3 (#24).

[0053] Furthermore, based on the estimated weight of the article 7, the displacement amount estimation unit 69 estimates the displacement amount of the elastic support member 36 in the vertical direction Z (#25). Based on the estimated displacement amount of the elastic support member 36, when the article 7 is transferred to the transfer target location 97, the transfer control unit 62 adjusts the amount of descent of the holding unit 3 (#26).

[0054] Other embodiments (1) In the above embodiments, the description has been given mainly assuming a configuration in which the transmission torque detection unit 63 detects the transmission torque when the holder 3 is stopped at the upper limit position Pu or the lower limit position Pd of the lifting range of the holder 3. However, the present invention is not limited to such a configuration, and the transmission torque detection unit 63 may detect the transmission torque when the holder 3 is stopped at any position between the upper limit position Pu and the lower limit position Pd. In such a case, the weight estimation unit 64 estimates the weight of the article 7 using the radius of the wound member 43 as a variable.

[0055] (2) In each of the above embodiments, a configuration has been described as an example in which the transmission torque detection unit 63 detects the transmission torque while the holding unit 3 is stopped. However, the present invention is not limited to such a configuration, and the transmission torque detection unit 63 may detect the transmission torque while the holding unit 3 is being raised and lowered at a constant speed by the lifting device 4. In such a case, the weight estimation unit 64 estimates the weight of the article 7 using the radius of the wound member 43 as a variable.

[0056] (3) In each of the above embodiments, a configuration has been described as an example in which the weight estimation unit 64 estimates the weight of the article 7 based on a value obtained by applying a low-pass filter to the detection value of the transmission torque obtained by the transmission torque detection unit 63. However, the present invention is not limited to such a configuration, and the weight estimation unit 64 may estimate the weight of the article 7 by directly using the detection value of the transmission torque obtained by the transmission torque detection unit 63 (i.e., without passing through a filter).

[0057] (4) In the above first embodiment, a configuration has been described assuming that the judgment threshold serving as a reference for the detachment judgment unit 67 to make a detachment judgment is set to one specific value. However, the present invention is not limited to such a configuration, and the judgment threshold may be set to two or more different values. For example, a first judgment threshold for making a detachment judgment of only a part of the article 7 (e.g., the lid), and a second judgment threshold larger than the first judgment threshold for making a detachment judgment of the entire article 7 may be set.

[0058] (5) In the above first embodiment, a configuration has been described as an example in which, when the detachment determination unit 67 determines that at least a part of the article 7 has fallen off, the abnormality reporting unit 68 simply reports that an abnormality has occurred in the article 7 being transported. However, the present invention is not limited to such a configuration, and in such a case, in addition to the abnormality reporting unit 68 reporting the abnormality, the traveling control unit 61 may immediately stop the traveling of the traveling body 2.

[0059] (6) In the above second embodiment, a configuration has been described as an example in which 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. However, the present invention is not limited to such a configuration, and the elastic support member 36 may be interposed between the connecting portion 31 and the support bracket 35 below the connecting portion 31. In this case, the amount of displacement of the elastic support member 36 in the up-down direction Z is the amount of extension.

[0060] (7) In each of the above embodiments, the control device 6 may further include an overweight determination unit that determines whether or not the weight is overweight based on the weight of the article 7 estimated by the weight estimation unit 64. The overweight determination unit may determine that the weight is overweight, for example, when the estimated weight of the article 7 exceeds a predetermined maximum holding weight (which may be a weight with a slight margin added). When the overweight determination unit determines that the weight 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. When performing such an overweight determination, it is preferable to make the determination based on the estimated weight using the transmission torque detected in the first period T1 shown in FIG. 7, since this allows the presence or absence of the weight to be determined as quickly as possible.

[0061] (8) In each of the above embodiments, a configuration has been described as an example in which the transmission torque detection unit 63 detects the transmission torque based on the motor current flowing through the lift drive motor 45. However, the present invention is not limited to such a configuration, and for example, a torque sensor may be provided in the power transmission path between the rotating body 42 and the lift drive motor 45, and the transmission torque detection unit 63 may detect the transmission torque using the torque sensor.

[0062] (9) The configurations disclosed in the above-mentioned embodiments (including the above-mentioned embodiments and other embodiments; the same applies below) can be applied in combination with configurations disclosed in other embodiments, as long as no contradiction occurs. As for other configurations, the embodiments disclosed in this specification are illustrative in all respects and can be appropriately modified within the scope of the present disclosure.

[0063] Summary of the embodiment To summarize the above, an article transport vehicle according to the present disclosure preferably has the following configurations.

[0064] An article transport vehicle for transporting articles, The apparatus includes a holding unit that holds the article, a lifting device that lifts and lowers the holding unit, and a control device that controls the lifting device, The lifting device includes a rotating body, a wound member wound around the rotating body so as to be freely wound and unwound, and a lifting drive motor that rotates the rotating body, and is configured to lift and lower the holding part by winding and unwinding the wound member by rotating the rotating body while the holding part is suspended by the wound member, The control device includes: a transmission torque detection unit that detects a transmission torque transmitted between the rotating body and the lift drive motor; a weight estimation unit that estimates a weight of the item held by the holding unit based on the transmission torque detected by the transmission torque detection unit; Equipped with.

[0065] According to this configuration, the weight of the article held by the holder can be estimated under various conditions based on the transmitted torque detected between the rotor and the lift drive motor, and the estimated weight of the article thus obtained can be used to efficiently operate the article transport vehicle.

[0066] In one embodiment, It is preferable that the transmission torque detection unit detects the transmission torque in a lifting / lowering stopped state in which the lifting / lowering of the holding part by the lifting device is stopped, or in a constant speed lifting / lowering state in which the lifting device lifts and lowers the holding part at a constant speed.

[0067] According to this configuration, the transmission torque is detected without the acceleration caused by the lifting and lowering movement of the holding part by the lifting device acting on the article, making it easier to improve the accuracy of weight estimation.

[0068] In one embodiment, It is preferable that the transmission torque detection section detects the transmission torque in a state in which the holding section is stopped at an upper limit position of a lifting range of the holding section.

[0069] In many cases, when the holding part is at the upper limit of the lifting range, a large amount of the wound material is wound around the rotor. As the length of the wound material wound around the rotor increases, the outer diameter of the wound material wound around the rotor increases, and the torque required to support the article increases in proportion to the increase. For this reason, by detecting the transmission torque while the rotor is stopped at the upper limit of the lifting range as described above, the detection error can be relatively reduced and the accuracy of the weight estimation can be improved compared to, for example, detecting the transmission torque while the rotor is stopped at the lower limit of the lifting range.

[0070] In one embodiment, A traveling body is connected to the holding unit and the lifting device and travels along a travel path, The control device includes: a recording unit that records the weight of the item estimated by the weight estimation unit as a pre-travel weight before the traveling body starts traveling; a monitoring unit that continuously monitors the weight of the item estimated by the weight estimation unit while the traveling body is traveling; a detachment determination unit that determines that at least a portion 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 travel becomes equal to or greater than a predetermined determination threshold value; It is preferable that the device further comprises:

[0071] According to this configuration, even if the article transport vehicle is not provided with a falling-off detection sensor, the estimated result of the weight of the article based on the detected transmission torque can be continuously monitored, and it is possible to detect when at least a part of the article falls off. Therefore, it is possible to provide the article transport vehicle with a falling-off detection function while simplifying the configuration and reducing costs.

[0072] In one embodiment, It is preferable that the weight estimation unit estimates the weight of the item based on a value obtained by applying a low-pass filter to the detection value of the transmission torque obtained by the transmission torque detection unit.

[0073] According to this configuration, it is possible to reduce high-frequency components of the vibrations of the article transport vehicle caused by the structure of the article transport vehicle, the state of the travel route, etc., and to minimize fluctuations in the estimated value of the weight of the article, thereby making it easier to improve the accuracy of determining whether an article has fallen off.

[0074] In one embodiment, the holding section includes an article support section that contacts the article to support the article, a connecting section that is connected to the lifting device, and an elastic support member that supports the article support section in a vertically elastic state relative to the connecting section; It is preferable that the control device further includes a displacement amount estimating unit that estimates an amount of displacement of the elastic support member in a vertical direction based on the weight of the article estimated by the weight estimating unit.

[0075] According to this configuration, when the holding part includes an elastic support member, it is possible to estimate the vertical displacement of the elastic support member due to the weight of the article, and therefore it is possible to appropriately estimate the change in the vertical position of the article due to the fluctuation in the displacement of the elastic support member.

[0076] In one embodiment, When the control device lowers the holding unit while holding the item to transfer the item to a transfer target location, it is preferable that the control device adjusts the amount of descent of the holding unit by the lifting device to be smaller in response to an increase in the estimated displacement amount by the displacement amount estimation unit.

[0077] With this configuration, even if the displacement amount of the elastic support member varies for each item due to differences in weight for each item, the item can be lowered to an appropriate height relative to the transfer target location by appropriately adjusting the amount of descent of the holding part.

[0078] It is sufficient for an article transport vehicle according to the present disclosure to achieve at least one of the effects described above. [Explanation of symbols]

[0079] 1 Goods transport vehicle 2. Running body 3 Holding part 4 Lifting device 6. Control device 7 Goods 22 Travel drive motor 31 Connecting part 32 Article support part 36 Elastic support member 42 Rotating Body 43 Part to be wound 45 Lift drive motor 63 Transmission torque detector 64 Weight estimation section 65 Recording Section 66 Monitoring Department 67 Dropping judgment part 68 Abnormality reporting department 69 Displacement Estimation Unit 97 Transfer target location Pu upper limit position

Claims

1. An article transport vehicle for transporting articles, The apparatus includes a holding unit that holds the article, a lifting device that lifts and lowers the holding unit, and a control device that controls the lifting device, The lifting device includes a rotating body, a wound member wound around the rotating body so as to be freely wound and unwound, and a lifting drive motor that rotates the rotating body, and is configured to lift and lower the holding part by winding and unwinding the wound member by rotating the rotating body while the holding part is suspended by the wound member, The control device includes: a transmission torque detection unit that detects a transmission torque transmitted between the rotating body and the lift drive motor; a weight estimation unit that estimates a weight of the item held by the holding unit based on the transmission torque detected by the transmission torque detection unit; An article transport vehicle comprising:

2. The article transport vehicle of claim 1, wherein the transmission torque detection unit detects the transmission torque in a lifting / lowering stop state in which the lifting / lowering of the holding part by the lifting device is stopped, or in a constant speed lifting / lowering state in which the lifting / lowering of the holding part is raised and lowered at a constant speed by the lifting device.

3. The article transport vehicle according to claim 1 , wherein the transmission torque detector detects the transmission torque when the holder is stopped at an upper limit position of a lifting range of the holder.

4. A traveling body is connected to the holding unit and the lifting device and travels along a travel path, The control device includes: a recording unit that records the weight of the item estimated by the weight estimation unit as a pre-travel weight before the traveling body starts traveling; a monitoring unit that continuously monitors the weight of the item estimated by the weight estimation unit while the traveling body is traveling; a detachment determination unit that determines that at least a portion 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 travel becomes equal to or greater than a predetermined determination threshold value; The article transport vehicle of claim 1 , further comprising:

5. 5. The article transport vehicle according to claim 4, wherein the weight estimation unit estimates the weight of the article based on a value obtained by applying a low-pass filter to a detection value of the transmission torque obtained by the transmission torque detection unit.

6. the holding section includes an article support section that contacts the article to support the article, a connecting section that is connected to the lifting device, and an elastic support member that supports the article support section in a vertically elastic state relative to the connecting section; The item transport vehicle of any one of claims 1 to 3, wherein the control device further includes a displacement amount estimation unit that estimates the amount of vertical displacement of the elastic support member based on the weight of the item estimated by the weight estimation unit.

7. The item transport vehicle of claim 6, wherein when the holding section is lowered while holding the item to transfer the item to a transfer target location, the control device adjusts the amount of descent of the holding section by the lifting device to be smaller in response to an increase in the estimated displacement amount by the displacement amount estimation section.

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