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 Art

[0002] Article transport vehicles for transporting articles have been put into use. An example of such an article transport vehicle is disclosed in Japanese Patent Laid-Open No. 2020-200145 (Patent Document 1).

[0003] The article transport vehicle (crane 1) of Patent Document 1 includes a holding portion (claw 30) that holds an article (object to be transported), an elevating device (hoisting device 22) that elevates and lowers the holding portion, and a control device (control unit 44) that controls the elevating device. The elevating device includes a wound member (wire rope 23) wound to be freely wound up and let out, and an elevating drive motor (motor 41) that rotationally drives a rotating body around which the wound member is wound. The control device monitors the torque of the elevating drive motor. Prior Art Documents Patent Documents

[0004] Patent Document 1 Japanese Patent Laid-Open No. 2020-200145 Summary of the Invention Problems to be Solved by the Invention

[0005] In the article transport vehicle of Patent Document 1, while monitoring the torque of the elevating drive motor, the control device only urgently stops the rotation of the elevating drive motor when it detects that the motor torque exceeds a predetermined threshold value. That is, the technology disclosed in Patent Document 1 is merely a fail-safe technology that only prevents the occurrence of abnormalities in advance. However, it is preferable that the torque of the elevating drive motor can be used to enable more proactive and efficient operation of the article transport vehicle.

[0006] Therefore, it is desirable to enable the efficient operation of the material handling vehicle by utilizing the torque of the lifting drive motor. [Means for solving the problem]

[0007] The goods transport vehicle related to this disclosure is A transport vehicle for transporting goods, The device comprises a holding section for holding the article, a lifting device for raising and lowering the holding section, and a control device for controlling the lifting device. The lifting device comprises a rotating body, a member to be wound around the rotating body so as to be able to be wound and unwound, and a lifting drive motor that rotates the rotating body. The device is configured to raise and lower the holding part by winding and unwinding the member to be wound, while the holding part is suspended by the member to be wound. The control device is A transmission torque detection unit for detecting the transmission torque transmitted between the rotating body and the lifting drive motor, A weight estimation unit estimates the weight of the article held by the holding unit based on the transmission torque detected by the transmission torque detection unit, It is equipped with.

[0008] This configuration allows for the detection of the transmission torque between the rotating body and the lifting drive motor, and based on that transmission torque, the weight of the item held by the holding unit can be estimated under various conditions. The estimated weight of the item obtained in this way can then be used to improve the efficiency of the item transport vehicle.

[0009] Further features and advantages of the technology relating to this disclosure will become clearer from the following description of exemplary and non-limiting embodiments, with reference to the drawings. [Brief explanation of the drawing]

[0010] [Figure 1] Side view of the article conveying equipment according to the first embodiment [Figure 2] Side view of a goods transport vehicle [Figure 3] Front view of a goods transport vehicle [Figure 4] Perspective view of the lifting device [Figure 5] Block diagram of the control system [Figure 6] Flowchart showing the processing steps for the elimination determination process. [Figure 7] Time chart of the lifting speed of the holding unit and the torque of the lifting drive motor. [Figure 8] Schematic diagram of the holding section of the article transport vehicle in the second embodiment. [Figure 9] Block diagram of the control system [Figure 10] Flowchart showing the processing procedure for adjusting the amount of descent [Modes for carrying out the invention]

[0011] [First Embodiment] The first embodiment of the goods transport vehicle will be described with reference to the drawings. The goods transport vehicle 1 of this embodiment is used, for example, in a semiconductor manufacturing plant to transport goods 7. As shown in Figures 1 and 2, the goods transport vehicle 1 comprises a traveling body 2, a holding unit 3, and a lifting device 4. The goods transport vehicle 1 also comprises a control device 6 (see Figure 5) that controls the traveling body 2, the holding unit 3, and the lifting device 4.

[0012] The traveling body 2 travels along the travel path, and the holding unit 3 and the lifting device 4 are connected to the traveling body 2 while being suspended and supported by the traveling body 2. In this way, the entire goods transport vehicle 1 travels along the travel path. In this embodiment, the travel path of the goods transport vehicle 1 is physically formed by rails 92 suspended and supported from the ceiling 91. That is, the goods transport vehicle 1 of this embodiment is an overhead transport vehicle that moves along rails 92 formed along the ceiling 91.

[0013] The article 7, which is an object to be conveyed by the article conveyance vehicle 1, is not particularly limited, and examples thereof include containers such as a wafer container that accommodates wafers (a so-called FOUP: Front Opening Unified Pod), and a reticle container that accommodates reticles (a so-called reticle pod). As shown in FIG. 2, the article 7 of the present embodiment includes a container body 71 and a flange 72 provided at an upper portion of the container body 71.

[0014] The article conveyance vehicle 1 conveys the article 7, for example, to a mounting table 96 of a processing apparatus 95 installed below a travel path. The article conveyance vehicle 1 transfers the article 7, lowers the article 7 by the lifting device 4, and carries the article 7 into a transfer target position 97 (for example, an upper surface) of the mounting table 96. Further, the article conveyance vehicle 1 lifts the article 7 by the lifting device 4 while holding the article 7 placed at the transfer target position 97 of the mounting table 96, and unloads the article 7 from the transfer target position 97. Note that the height of the transfer target position 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 travel drive motor 22, wheels 23, and guide wheels 24. The vehicle body 21 supports the travel drive motor 22, the wheels 23, the guide wheels 24, and the like. The travel drive motor 22 includes an electric motor such as a servomotor, for example, and drives at least one wheel 23. The wheels 23 roll on an upper surface of the rail 92. The wheel 23 drivingly connected to the travel drive motor 22 functions as a drive wheel. The guide wheels 24 roll on inner side surfaces of the rails 92. The traveling body 2 travels on the rails 92 along the rails 92 in a state where the guide wheels 24 are guided in contact with the inner side surfaces of the rails 92.

[0016] In the following description, the direction along the extending direction of the rails 92, which is the direction in which the traveling body 2 travels, is referred to as the front-rear direction X of the article transport vehicle 1. Further, 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. Further, 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. Note that each of these directions is a direction 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 movement 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 arranged below the rails 92. The lifting device 4 is housed inside a cover body 50 that is suspended and supported from the traveling body 2. The holding unit 3 is housed inside the cover body 50 in a state of being positioned at the upper limit position Pu of the lifting range. The cover body 50 includes an upper cover portion 51 that covers the upper side, and a pair of side cover portions 52 that cover both sides in the front-rear direction X. At least one side in the left-right direction Y (both sides in this example) of the internal space of the cover body 50 is open.

[0018] The holding unit 3 is a portion for holding an article 7. As shown in FIG. 2 and FIG. 3, the holding unit 3 includes a connecting portion 31, an article supporting 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 also functions as a base (holding main body portion) of the holding unit 3 in the present embodiment. The connecting portion 31 supports the article supporting portion 32 slidably in the front-rear direction X. Further, the connecting portion 31 fixedly supports the holding drive motor 33.

[0019] The article support portion 32 contacts the article 7 and supports it. In this embodiment, the article support portion 32 supports the flange 72 of the article 7 from below. In this embodiment, a pair of article support portions 32 are provided so that the flange 72 of the article 7 can be simultaneously supported from both sides in the front-rear direction X. These pair of article support portions 32 are provided side by side in the front-rear direction X with a predetermined distance between them. The pair of article support portions 32 are configured to slide freely in the front-rear direction X, and move closer to or further apart 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, for example, via a ball screw mechanism. The holding drive motor 33 moves the pair of article support parts 32 in opposite directions so that they move closer to each other or further apart from each other along the front-rear direction X.

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

[0022] The lifting drive motor 45 is connected to the rotating body 42 via a transmission 46 so as to be able to transmit driving force. The lifting drive motor 45 rotates the rotating body 42 so as to wind the winded member 43 onto the rotating body 42 or unwind the winded member 43 from the rotating body 42. In this embodiment, the transmission 46 is a reduction gear and reduces the rotation of the lifting drive motor 45 and transmits it to the rotating body 42.

[0023] In this configuration, the lifting device 4 suspends the holding unit 3 by the winding member 43, and raises and lowers the holding unit 3 by winding and unwinding the winding member 43 by rotating the rotating body 42.

[0024] The control device 6 controls the operation of the goods transport vehicle 1. The control device 6 controls the operation of the goods transport vehicle 1 by controlling the traveling 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 installed on the goods transport vehicle 1 and controls the operation of the goods transport vehicle 1 by receiving commands from a higher-level control device 60 installed in a control facility not shown. It is also possible that the control devices 6 installed on each of the multiple goods transport vehicles 1 can communicate with each other.

[0025] As shown in Figure 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 detachment determination unit 67, and an abnormality alarm unit 68. The control device 6 also includes a arithmetic processing unit such as a CPU (Central Processing Unit) and a main memory such as RAM (Random Access Memory) or ROM (Read Only Memory). Each functional unit of the control device 6 is realized through the cooperation of the arithmetic processing unit and the program executed on the arithmetic processing unit.

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

[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 support and release 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 raising and lowering of the holding unit 3. Finally, the transfer control unit 62 controls the transfer of the article 7 by coordinating the operation of the holding drive motor 33 and the operation of the lifting drive motor 45.

[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 lifting drive motor 45. In this embodiment, the transmission torque detection unit 63 detects the motor torque based on the motor current flowing through the lifting drive motor 45, and detects the transmission torque based on the obtained motor torque. In a configuration in which a transmission 46 is interposed between the rotating body 42 and the lifting 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] The timing for detecting the transmitted torque is not particularly limited, but it is preferable for the transmitted torque detection unit 63 to detect the transmitted torque when the lifting and lowering of the holding unit 3 by the lifting and lowering device 4 is stopped. In the lifting and lowering stopped state, the motor current flowing to the lifting and lowering drive motor 45 is only for supporting the item 7, so there is less noise and the transmitted torque can be detected with high accuracy.

[0030] For example, in the example in Figure 7, it is preferable that the transmission torque detection unit 63 detects the transmission torque during the first period T1 or the second period T2, when the lifting speed of the holding unit 3 is "0 (zero)". In Figure 7, the lifting speed of the holding unit 3 is represented by positive values ​​for the lowering speed and negative absolute values ​​for the upward speed. The torque of the lifting drive motor 45 is represented by positive values ​​for the torque that lowers the holding unit 3 and negative absolute values ​​for the torque that raises the holding unit 3, and each is shown as a percentage of the rated torque. The horizontal axis represents time.

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

[0032] Furthermore, while the position for detecting the transmitted torque is not particularly limited, it is preferable for the transmitted torque detection unit 63 to detect the transmitted torque when the holding unit 3 is stopped at the upper limit position Pu of the holding unit 3's lifting range. When the holding unit 3 is stopped at the upper limit position Pu, the amount of winding of the winded member 43 onto the rotating body 42 is at its maximum, and its radius is at its maximum, so the transmitted torque becomes large and the influence of noise becomes relatively small. Therefore, the transmitted 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 transmitted torque detected by the transmitted torque detection unit 63. When the holding unit 3 holds the article 7 due to the torque of the lifting drive motor 45, the following force balance is achieved in the winded member 43 wound around the rotating body 42. (Transmitted torque) = (Radius of the winding member 43) × (Force acting on article 7) ... (A)

[0034] Here, the radius of the winding member 43 is determined by the sum of the radius of the rotating body 42 and the total thickness of the winding member 43 wound around the rotating body 42. Also, the force acting on the article 7 is determined by the product of the weight of the article 7 and the acceleration due to gravity. Therefore, the weight of the article 7 is calculated based on the above equation (A), using the transmission torque detected by the transmission torque detection unit 63 and the radius of the winding member 43 as variables, and the weight estimation unit 64 estimates this as the weight of the article 7.

[0035] In this embodiment, where the holding unit 3 is stopped at the upper limit position Pu, the transmission torque detection unit 63 detects the transmission torque. Since the radius of the winding member 43 can also be considered a constant, the weight estimation unit 64 can essentially estimate the weight of the item 7 using only the transmission torque as a variable. The radius of the winding member 43 when the holding unit 3 is stopped at the upper limit position Pu should be obtained in advance by measurement and kept as a specified value.

[0036] Incidentally, when the holding unit 3 is stopped at the upper limit position Pu, the article 7 is housed inside the cover body 50, and the article transport vehicle 1 may be transporting the article 7 in this state. In such cases, vibrations associated with the movement of the article transport vehicle 1 (for example, vibrations caused by the travel path such as steps or junctions in the rails 92, or vibrations caused by the article transport vehicle 1 itself, such as the wheels 23 and the drive transmission system) may adversely affect the detection of the transmitted torque and, consequently, the estimation of the weight of the article 7. Therefore, it is preferable for the weight estimation unit 64 to estimate the weight of the article 7 based on a value obtained by applying a low-pass filter to the detected value of the transmitted torque obtained by the transmitted torque detection unit 63.

[0037] The recording unit 65 records the weight of the items 7, estimated by the weight estimation unit 64, as the pre-travel weight before the item transport vehicle 1 (traveling body 2) starts traveling. The recording unit 65 reserves a temporary storage area in the main memory of the control device 6 and records the pre-travel weight in this temporary storage area.

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

[0039] The detachment determination unit 67 determines that at least a part of the item 7 has detached if the difference between the latest estimated weight of the item 7, as known by the monitoring unit 66, and the weight before the start of travel exceeds a predetermined determination threshold. Both the weight of the item 7 before the start of travel and the latest estimated weight are recorded in the temporary storage area of ​​the main memory of the control device 6. Based on these, the detachment determination unit 67 monitors the weight difference of the item 7 from before the start of travel. The determination threshold can be set to a slightly lighter value, for example, depending on the weight of a part of the item 7 (for example, the lid of a container or the contents contained therein). When the detachment determination unit 67 determines that at least a part of the item 7 has detached if the weight difference of the item 7 from before the start of travel exceeds the determination threshold, it notifies the abnormality alarm unit 68 of this fact.

[0040] When the abnormality alarm unit 68 receives notification from the detachment determination unit 67 that a detachment has occurred, it issues an alarm indicating that an abnormality has occurred in the item 7 being transported by the item transport vehicle 1. The abnormality alarm by the abnormality alarm unit 68 can be issued, for example, by displaying an abnormality on the control computer's monitor or by sounding a warning sound from a speaker.

[0041] The procedure for determining whether an item has fallen off, which is performed in the item transport vehicle 1 of this embodiment, will now be described. In this embodiment, the detection of the transmitted torque and the estimation of the weight of the item 7 are performed at the upper limit position Pu. As shown in Figure 6, first, the holding unit 3, which is holding the item 7, is raised (step #01). Then, it is determined whether the holding unit 3 has 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 holding unit 3 stopped 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 (#03). Based on the detected transmission torque, the weight estimation unit 64 estimates the weight of the item 7 held by the holding unit 3 (#04). This detection of transmission torque and the estimation of the weight of the item 7 based on it are performed continuously at predetermined intervals.

[0043] In this embodiment, the estimated weight of the item 7 before the item transport vehicle 1 (mobile body 2) starts moving is recorded by the recording unit 65 as the weight before starting to move (#05). Furthermore, even after the item transport vehicle 1 (mobile body 2) starts moving, the monitoring unit 66 continuously records the estimated weight of the item 7 (#06). Based on the weight before starting to move and the latest estimated weight of the item 7, the monitoring unit 66 continuously monitors the weight difference of the item transport vehicle 1 (mobile body 2) from before it started moving (#07).

[0044] The detachment determination unit 67 determines whether the weight difference from before the start of travel has exceeded a predetermined threshold (#08). As long as the weight difference is less than the 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 exceeds the threshold (#08: Yes), the detachment determination unit 67 determines that at least a part of the item 7 has detached (#09). In addition, the abnormality alarm unit 68 issues an alarm indicating that an abnormality has occurred in the item 7 being transported (#10).

[0045] [Second Embodiment] The article transport vehicle of the second embodiment will be described with reference to the drawings. The article transport vehicle 1 of this embodiment differs in some specific configuration of the holding section 3 from that of the first embodiment. Consequently, the control content executed in the article transport vehicle 1 also differs in some aspects from that of the first embodiment. The differences between the article transport vehicle 1 of this embodiment and the first embodiment will be described below. Unless otherwise specified, the parts are the same as in the first embodiment and are denoted by the same reference numerals, and detailed explanations will be omitted.

[0046] As shown in Figure 8, the holding section 3 of the article transport vehicle 1 in this embodiment further includes a support bracket 35 and an elastic support member 36, in addition to the connecting section 31, the article support section 32, and the holding drive motor 33 (see Figure 9). A pair of support brackets 35 are provided corresponding to the article support section 32. The support brackets 35 are connected to and fixed to the corresponding article support section 32. The pair of support brackets 35 are provided side by side in the front-rear direction X with a predetermined distance between them. The pair of support brackets 35 are configured to slide freely in the front-rear direction X together with the article support section 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 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 elasticity in the vertical Z direction relative to the connecting portion 31. By providing such an elastic support member 36, vibrations of the traveling body 2 caused by the traveling body 2's movement, and vibrations of the holding portion 3 caused by the lifting device 4 raising and lowering, can be dampened. Therefore, the article 7 can be stably supported with minimal vibration, and consequently, the weight of the article 7 can be estimated with accuracy. In this embodiment, the elastic support member 36 is composed of a compressed coil spring.

[0048] As shown in Figure 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 estimation unit 69 estimates the vertical Z displacement of the elastic support member 36 based on the weight of the article 7 estimated by the weight estimation unit 64. In this embodiment, the elastic support member 36 is provided in a compressed state between the connecting part 31 and the support bracket 35, and the vertical Z displacement is the amount of compression. The displacement estimation unit 69 also estimates the vertical Z displacement of the elastic support member 36 based on the vertical Z dimension of the elastic support member 36 when the holding part 3 is not holding the article 7. The relationship between the weight of the article 7 and the vertical Z displacement of the elastic support member 36 is stored in advance, and the displacement estimation unit 69 calculates the vertical Z displacement of the elastic support member 36 by substituting the weight of the article 7 estimated by the weight estimation unit 64 into this relationship formula.

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

[0051] The processing procedure for adjusting the lowering amount performed in the item transport vehicle 1 of this embodiment will be described. In this embodiment as well, the detection of the transmitted torque and the estimation of the weight of the item 7 are performed at the upper limit position Pu. As shown in Figure 10, first, the holding unit 3 holding the item 7 is raised (step #21). Then, it is determined whether or not the holding unit 3 has stopped at the upper limit position Pu (#22). The raising of the holding unit 3 continues until it is determined that it has stopped at the upper limit position Pu (#22: Yes).

[0052] With the holding unit 3 stopped 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). Based on the detected transmission torque, the weight estimation unit 64 estimates the weight of the item 7 held by the holding unit 3 (#24).

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

[0054] [Other Embodiments] (1) In each of the above embodiments, the transmission torque detection unit 63 has been described primarily assuming a configuration in which the transmission torque is detected when the holding unit 3 is stopped at the upper limit position Pu or the lower limit position Pd of the lifting range of the holding unit 3. However, the transmission torque detection unit 63 may also be limited to detecting the transmission torque when the holding unit 3 is stopped at any position between the upper limit position Pu and the lower limit position Pd. In such cases, the weight estimation unit 64 estimates the weight of the article 7, also using the radius of the winding member 43 as a variable.

[0055] (2) In the above embodiments, the transmission torque detection unit 63 was described as an example in which it detects the transmission torque when the holding unit 3 is stopped. However, the transmission torque detection unit 63 is not limited to such an embodiment, and may also detect the transmission torque in a constant-speed lifting state in which the holding unit 3 is lifted 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, also using the radius of the winded member 43 as a variable.

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

[0057] (4) In the first embodiment described above, the configuration was mainly assumed in which the judgment threshold used as a criterion for the detachment determination unit 67 to perform detachment determination is set to a specific single value. However, the configuration is not limited to such a configuration, and the judgment threshold may be set to two or more values. For example, a first judgment threshold may be set for determining the detachment of only a part of the article 7 (e.g., the lid), and a second judgment threshold that is greater than the first judgment threshold may be set for determining the detachment of the entire article 7.

[0058] (5) In the first embodiment described above, the configuration was described as one in which, when the detachment determination unit 67 determines that at least a part of the article 7 has detached, the abnormality alarm unit 68 simply issues an alarm indicating that an abnormality has occurred in the article 7 being transported. However, the configuration is not limited to such an example, and in such a case, in addition to the abnormality alarm issued by the abnormality alarm unit 68, the travel control unit 61 may immediately stop the travel of the travel body 2.

[0059] (6) In the second embodiment described above, an example configuration was described 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 configuration is not limited to this, 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 displacement of the elastic support member 36 in the vertical direction Z is the amount of elongation.

[0060] (7) In each of the above embodiments, the control device 6 may further include a weight overload determination unit that determines whether or not the weight is overloaded based on the weight of the article 7 estimated by the weight estimation unit 64. The weight overload determination unit may determine that the weight is overloaded, for example, when the estimated weight of the article 7 exceeds a predetermined maximum holding weight (which may be a weight that includes a small margin). If the weight overload determination unit determines that the weight is overloaded, 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 a weight overload 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 Figure 7, as this allows for a quick determination of whether or not the weight is overloaded.

[0061] (8) In each of the above embodiments, a configuration in which the transmission torque detection unit 63 detects the transmission torque based on the motor current flowing to the lifting drive motor 45 was described as an example. However, the configuration 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 lifting 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 each of the above-described embodiments (including the above-described embodiments and other embodiments; the same applies hereinafter) can be applied in combination with configurations disclosed in other embodiments, insofar as they do not cause a conflict. With respect to other configurations, the embodiments disclosed herein are illustrative in all respects and can be modified as appropriate without departing from the spirit of the disclosure.

[0063] [Summary of the Embodiments] In summary, the goods transport vehicle according to this disclosure preferably comprises the following components.

[0064] A transport vehicle for transporting goods, The device comprises a holding section for holding the article, a lifting device for raising and lowering the holding section, and a control device for controlling the lifting device. The lifting device comprises a rotating body, a member to be wound around the rotating body so as to be able to be wound and unwound, and a lifting drive motor that rotates the rotating body. The device is configured to raise and lower the holding part by winding and unwinding the member to be wound, while the holding part is suspended by the member to be wound. The control device is A transmission torque detection unit for detecting the transmission torque transmitted between the rotating body and the lifting drive motor, A weight estimation unit estimates the weight of the article held by the holding unit based on the transmission torque detected by the transmission torque detection unit, It is equipped with.

[0065] This configuration allows for the detection of the transmission torque between the rotating body and the lifting drive motor, and based on that transmission torque, the weight of the item held by the holding unit can be estimated under various conditions. The estimated weight of the item obtained in this way can then be used to improve the efficiency of the item transport vehicle.

[0066] As one aspect, Preferably, the transmission torque detection unit detects the transmission torque when the lifting device stops the lifting and lowering of the holding part, or when the lifting device lifts and lowers the holding part at a constant speed.

[0067] This configuration allows for the detection of transmitted torque while the acceleration caused by the lifting and lowering movement of the holding part by the lifting device is not acting on the item, thus improving the accuracy of weight estimation.

[0068] As one aspect, Preferably, the transmission torque detection unit detects the transmission torque when the holding unit is stopped at the upper limit position of the holding unit's lifting range.

[0069] In many cases, when the holding part is at the upper limit of the lifting range, the amount of material wound onto the rotating body is large. As the length of the material wound onto the rotating body increases, the outer diameter of the material wound onto the rotating body increases, and the torque required to support the item increases proportionally. Therefore, by detecting the transmitted torque when the device is stopped at the upper limit of the lifting range, as described above, the detection error can be relatively reduced and the accuracy of weight estimation can be improved compared to, for example, detecting the transmitted torque when the device is stopped at the lower limit of the lifting range.

[0070] As one aspect, The vehicle further comprises a vehicle connected to the holding part and the lifting device, which travels along the travel path, The control device is A recording unit records the weight of the item estimated by the weight estimation unit as the weight before the vehicle starts moving, A monitoring unit continuously monitors the weight of the article estimated by the weight estimation unit while the vehicle is in motion. A detachment determination unit determines that at least a part of the item has detached when the difference between the latest estimated weight of the item, as known by the monitoring unit, and the weight before the start of travel exceeds a predetermined determination threshold, It is preferable to have even more of these features.

[0071] With this configuration, even if the material transport vehicle is not equipped with a detachment detection sensor, the estimated weight of the material based on the detected transmission torque can be continuously monitored, and if at least a part of the material detaches, it can be detected. Therefore, it is possible to simplify the configuration and reduce costs while still equipping the material transport vehicle with a detachment detection function.

[0072] As one aspect, Preferably, the weight estimation unit estimates the weight of the article based on a value obtained by applying a low-pass filter to the detected value of the transmission torque obtained by the transmission torque detection unit.

[0073] This configuration reduces the high-frequency components of vibrations in the transport vehicle caused by factors such as its structure and the condition of its travel path, thereby minimizing fluctuations in the estimated weight of the goods. Consequently, it is easier to improve the accuracy of detecting when goods may fall off.

[0074] As one aspect, The holding portion comprises an article support portion that contacts and supports the article, a connecting portion connected to the lifting device, and an elastic support member that supports the article support portion in an elastic manner in the vertical direction relative to the connecting portion. Preferably, the control device further includes a displacement estimation unit that estimates the vertical displacement of the elastic support member based on the weight of the article estimated by the weight estimation unit.

[0075] With this configuration, when the holding part is equipped with an elastic support member, the amount of vertical displacement of the elastic support member due to the weight of the article can be estimated. Therefore, the change in the vertical position of the article due to fluctuations in the displacement of the elastic support member can be appropriately estimated.

[0076] As one aspect, When the control device lowers the holding part while the holding part is holding the article and moves the article to the transfer target location, it is preferable to adjust the amount by which the lifting device lowers the holding part in accordance with the increase in the estimated displacement amount by the displacement amount estimation unit.

[0077] With this configuration, even if the amount of displacement of the elastic support member changes for each item due to the different weights of each item, the amount of descent of the holding part can be appropriately adjusted to lower the item to an appropriate height relative to the transfer location.

[0078] The goods transport vehicle relating to this disclosure only needs 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. Drive motor 31 Connecting part 32 Article support part 36 Elastic support member 42. Solids of revolution 43 Part to be wound 45 Lifting drive motor 63 Torque detection unit 64 Weight estimation section 65 Records Section 66 Monitoring Department 67 Dropping judgment part 68 Abnormality reporting department 69 Displacement Estimation Unit 97 Sections to be reprinted Pu upper limit position

Claims

1. A transport vehicle for transporting goods, The system comprises a holding section for holding the article, a lifting device for raising and lowering the holding section, a control device for controlling the lifting device, and a traveling body connected to the holding section and the lifting device and traveling along a travel path. The lifting device comprises a rotating body, a member to be wound around the rotating body so as to be able to be wound and unwound, and a lifting drive motor that rotates the rotating body. The device is configured to raise and lower the holding part by winding and unwinding the member to be wound, while the holding part is suspended by the member to be wound. The control device is A transmission torque detection unit for detecting the transmission torque transmitted between the rotating body and the lifting drive motor, A weight estimation unit estimates the weight of the article held by the holding unit based on the transmission torque detected by the transmission torque detection unit, A recording unit records the weight of the item estimated by the weight estimation unit as the weight before the vehicle starts moving, A monitoring unit continuously monitors the weight of the article estimated by the weight estimation unit while the vehicle is in motion. A detachment determination unit determines that at least a part of the item has detached when the difference between the latest estimated weight of the item, as known by the monitoring unit, and the weight before the start of travel exceeds a predetermined determination threshold, A transport vehicle equipped with the following features.

2. The article transport vehicle according to claim 1, wherein the weight estimation unit estimates the weight of the article based on a value obtained by applying a low-pass filter to the detected value of the transmission torque obtained by the transmission torque detection unit.

3. A transport vehicle for transporting goods, The device comprises a holding section for holding the article, a lifting device for raising and lowering the holding section, and a control device for controlling the lifting device. The lifting device comprises a rotating body, a member to be wound around the rotating body so as to be able to be wound and unwound, and a lifting drive motor that rotates the rotating body. The device is configured to raise and lower the holding part by winding and unwinding the member to be wound, while the holding part is suspended by the member to be wound. The control device is A transmission torque detection unit for detecting the transmission torque transmitted between the rotating body and the lifting drive motor, A weight estimation unit estimates the weight of the article held by the holding unit based on the transmission torque detected by the transmission torque detection unit, Equipped with, The holding portion comprises an article support portion that contacts and supports the article, a connecting portion connected to the lifting device, and an elastic support member that supports the article support portion in an elastic manner in the vertical direction relative to the connecting portion. The control device further comprises a displacement estimation unit that estimates the vertical displacement of the elastic support member based on the weight of the article estimated by the weight estimation unit, in an article transport vehicle.

4. The article transport vehicle according to claim 3, wherein when the holding part is lowered while the article is being held by the holding part to transfer the article to the transfer target location, the control device adjusts to reduce the amount by which the lifting device lowers the holding part in accordance with the increase in the estimated displacement by the displacement estimation unit.

5. The article transport vehicle according to any one of claims 1 to 4, wherein the transmitted torque detection unit detects the transmitted torque in a lifting-stop state in which the lifting device stops the lifting of the holding part, or in a constant-speed lifting state in which the lifting device lifts the holding part up and down at a constant speed.

6. The article transport vehicle according to any one of claims 1 to 4, wherein the transmission torque detection unit detects the transmission torque when the holding unit is stopped at the upper limit position of the lifting range of the holding unit.

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