Item measuring device

Abstract

To provide a weighing device for goods that can suppress a decrease in production capacity without unnecessarily expanding the target weight range. [Solution] The article weighing device 1 includes a plurality of gripping units 20 that grip some articles from a group of articles and release the grips to discharge units 50, and a control unit 70 that performs combination weighing, selecting a combination of weight values ​​such that the sum of a plurality of weight values, which are weighed by the weighing unit 17 and associated with each of the plurality of gripping units 20, falls within a target weight range, and causes the gripping unit 20 to release the grips on the articles corresponding to the selected combinations. The control unit 70 performs a first combination weighing, selecting a combination of weight values ​​so that it falls within a first target weight range, and executes a first process to calculate the number of weight value combinations based on the first combination weighing. If the number of weight value combinations based on the first combination weighing satisfies a set value, the control unit 70 causes the gripping unit 20 to release the grips on the articles corresponding to the combinations selected by the first combination weighing.

Description

Technical Field

[0001] One aspect of the present invention relates to an article weighing device.

Background Art

[0002] As one type of weighing device, for example, Patent Document 1 below describes an article weighing device (article discharge system) that takes out and discharges some articles from a group of articles. In the article weighing device described in Patent Document 1 below, some articles in the group of articles are gripped by a plurality of gripping portions, and the weight values of the articles gripped by each of the gripping portions are measured by a weighing instrument. In the article weighing device, a combination of weight values is selected so that the total value of a plurality of weight values respectively associated with the plurality of gripping portions falls within a preset target weight range.

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Patent Document 2

Summary of the Invention

Problems to be Solved by the Invention

[0004] In such an article weighing device, a conventional combination weighing device, such as the one disclosed in Patent Document 2, is used. In each cycle of weighing and discharge from the weighing hopper, an article is supplied to the available weighing hopper. Therefore, the article only needs to be discharged from the weighing hopper with the combination closest to the target weighing value. However, in an article weighing device like the one shown in Patent Document 1, once multiple gripping parts grip an article placed on the mounting section, they will not grip the article again until the gripping part corresponding to the weight value combination selected by combination weighing is released. In such an article weighing device, setting a narrow target weight range reduces the number of weight value combinations selected by combination weighing. When the number of weight value combinations selected by combination weighing decreases, the number of times the multiple gripping parts grip the article from the mounting section increases, thus reducing production capacity.

[0005] Therefore, one aspect of the present invention is to provide an item weighing device that can suppress a decrease in production capacity without unnecessarily expanding the target weight range. [Means for solving the problem]

[0006] (1) An article weighing device according to one aspect of the present invention comprises: a mounting section on which a group of articles is placed; a plurality of gripping sections that grip some of the articles from the group of articles placed on the mounting section and discharge the articles to a discharge section by releasing the gripping; a weighing section that weighs the weight of the articles gripped by each of the plurality of gripping sections; and a control unit that performs combination weighing to select a combination of weight values ​​such that the sum of the plurality of weight values ​​weighed by the weighing section and associated with each of the plurality of gripping sections falls within a preset target weight range, and releases the gripping of the articles by the gripping sections corresponding to the selected combination. The control unit performs a first combination weighing to select a combination of weight values ​​such that it falls within a first target weight range, and executes a first process to calculate the number of weight value combinations based on the first combination weighing. If the number of weight value combinations based on the first combination weighing satisfies a set value, the control unit releases the gripping of the articles by the gripping sections corresponding to the combination selected by the first combination weighing.

[0007] If the range of the target weight is expanded because there are few combinations of weight values ​​selected by combination weighing, the number of combinations of weight values ​​based on combination weighing will increase. However, if the range of the target weight is expanded unnecessarily, the weight values ​​of each combination will tend to increase, and the yield will decrease. Therefore, in this configuration of the weighing device, the number of combinations of weight values ​​based on the first combination weighing is calculated, and based on the number of combinations of weight values ​​based on the first combination weighing, the gripping part corresponding to the combination selected by the first combination weighing is released. This makes it possible to expand the range of the target weight as needed, thus avoiding unnecessary expansion of the target weight range. As a result, the decrease in production capacity can be suppressed without unnecessarily expanding the target weight range.

[0008] (2) In the item weighing device described in (1) above, if the number of weight value combinations based on the first combination weighing does not meet the set value, the control unit may perform a second combination weighing to select weight value combinations so that the range of the first target weight range is expanded to a second target weight range, and perform a second process to calculate the number of weight value combinations based on the second combination weighing. If the number of weight value combinations based on the second combination weighing meets the set value, the control unit may release the grip of the item by the gripping part corresponding to the combination selected by the second combination weighing. In this configuration, the first control unit performs the second combination weighing only when the number of weight value combinations based on the first combination weighing does not meet the set value. This makes it possible to perform processing without delay even when a control unit with low processing capacity is used.

[0009] (3) In the weighing device for goods described in (1) above, the control unit may perform a second combination weighing, in which it selects a combination of weight values ​​to form a second target weight range which is an expanded range of the first target weight range, and calculate the number of combinations of weight values ​​based on the second combination weighing, regardless of the result of calculating the number of combinations of weight values ​​based on the first combination weighing. In this configuration, the first control unit can perform the first combination weighing and the second combination weighing simultaneously.

[0010] (4) In the article weighing device described in (2) or (3) above, the control unit may release the gripping part of the article corresponding to the combination selected by the first combination weighing if the number of weight value combinations based on the first combination weighing does not meet the set value and the number of weight value combinations based on the second combination weighing does not meet the set value. In this configuration, if both the number of weight value combinations based on the first combination weighing and the number of weight value combinations based on the second combination weighing with an expanded target weight range do not meet the set value, the gripping part of the article corresponding to the combination selected by the first combination weighing before the target weight range was expanded can be released. This makes it possible to avoid unnecessarily expanding the target weight range, even if the processing capacity is reduced.

[0011] (5) In the article weighing device described in any one of (1) to (4) above, the plurality of gripping parts include a plurality of first gripping parts arranged in a first area and a plurality of second gripping parts arranged in a second area, and the control unit may alternately perform gripping of the article placed on the placement part by the plurality of first gripping parts and gripping by the plurality of second gripping parts, and alternately perform combined weighing of the article gripped by the plurality of first gripping parts and release of the gripping part corresponding to the selected combination, and combined weighing of the article gripped by the plurality of second gripping parts and release of the gripping part corresponding to the selected combination. With this configuration, the rate at which articles within the target weight range or an expanded target weight range can be supplied to the downstream process at regular intervals can be increased. [Effects of the Invention]

[0012] According to one aspect of the present invention, it is possible to suppress a decrease in production capacity without unnecessarily expanding the target weight range. [Brief explanation of the drawing]

[0013] [Figure 1] Figure 1 is a front view of an article weighing device according to one embodiment. [Figure 2] Figure 2 is a block diagram of the weighing device shown in Figure 1. [Figure 3] Figure 3 is a flowchart showing the flow of combination weighing performed by the control unit. [Figure 4] Figure 4 is a sequence diagram of various operations in the first robot hand, second robot hand, and discharge chute according to this embodiment. [Figure 5] Figure 4 is a sequence diagram of various operations in the first robot hand, second robot hand, and discharge chute according to a conventional embodiment. [Figure 6] Figure 6 is a flowchart showing the flow of combination weighing performed by the control unit in the modified example. [Modes for carrying out the invention]

[0014] Hereinafter, an article weighing device 1 according to one embodiment will be described with reference to the drawings. In the description of the drawings, the same elements are denoted by the same reference numerals, and redundant explanations are omitted.

[0015] First, the item weighing device 1 will be described with reference to Figures 1 and 2. The item weighing device 1 shown in Figure 1 removes some items from the container (placement section) B so that the weight (mass) of some items falls within the target weight range, and discharges the items to the outside. The items discharged by the item weighing device 1 are then packaged in bags or placed in other containers in a subsequent process and shipped as goods. The items are, for example, food products such as noodles, meat, and seafood.

[0016] The item weighing device 1 comprises an item gripping device 10, a container moving device 30, a discharge chute (discharge section) 50, and a control unit 70.

[0017] The article gripping device 10 grips articles from a group of articles X stored in container B. The article gripping device 10 comprises a robot hand 15 having a plurality of gripping parts 20, and a hand drive unit 11 that moves the robot hand 15 in the horizontal direction. The robot hand 15 and the hand drive unit 11 are attached, for example, to the main frame 3.

[0018] In the article weighing device 1 of this embodiment, for example, a pair of robot hands 15, 15 having the same configuration are arranged side by side on the left and right. In the following description, the robot hand 15 arranged on the left side (first region) in the front view of FIG. 1 may be referred to as the first robot hand 15A, and the robot hand 15 arranged on the right side (second region) in the front view may be referred to as the second robot hand 15B. However, when describing the common configuration and functions, the name of the robot hand 15 is simply used.

[0019] The robot hand 15 has, for example, 16 gripping parts 20 arranged in four rows in the left - right direction. Each gripping part 20 has, for example, a plurality of gripping claws 21, and grips an article by closing the gripping claws 21. More specifically, the plurality of gripping claws 21 are moved from a state of being separated from each other to a state of approaching each other, thereby sandwiching the article between the plurality of gripping claws 21 to grip the article. Each gripping part 20 includes a gripping member drive mechanism 22 that drives the plurality of gripping claws 21. The gripping member drive mechanism 22 drives the gripping claws 21 using, for example, a motor or fluid pressure as a drive source. The robot hand 15 has a plurality of weighing devices (weighing parts) 17 that weigh the weight value of the article gripped by each gripping part 20. That is, 16 weighing devices 17 are provided for the 16 gripping parts 20.

[0020] Each weighing device 17 includes a sensor part (not shown) housed in the housing of the weighing device 17 and a weight acquisition part 17A. The sensor part includes, for example, a force sensor and an acceleration sensor. As the force sensor, for example, a strain - gauge type load cell is adopted. The acceleration sensor adopts, for example, a strain - gauge type load cell or a MEMS - type small acceleration sensor. The weight acquisition part 17A acquires the weight value of the article gripped by the gripping part 20 based on the force measured by the sensor part. Note that the weighing device 17 is not limited to the method of weighing the weight of the article based on the force measured when the gripping part 20 moves.

[0021] In the item weighing device 1, two hand drive units 11, 11, each having the same configuration, are provided corresponding to the first robot hand 15A and the second robot hand 15B. In the following description, the hand drive unit 11 located on the left side in the front view of Figure 1, which moves the first robot hand 15A, may be referred to as the first hand drive unit 11A, and the hand drive unit 11 located on the right side in the front view, which moves the second robot hand 15B, may be referred to as the second hand drive unit 11B. However, when describing the common configuration and function, the name "hand drive unit 11" will be used simply.

[0022] The hand drive unit 11 moves the robot hand 15 horizontally along two frames 13, 13 that extend parallel to each other. The hand drive unit 11 can move the block 12 that holds the robot hand 15 forward or backward. The hand drive unit 11 includes, for example, a servo motor, an air cylinder, etc., for moving the block 12.

[0023] The container moving device 30 moves the container B on which the group of articles X is placed in the vertical and horizontal directions, respectively. Container B is the member on which the group of articles X is placed. The container moving device 30 has a base 31 on which container B is held or placed, and a base drive unit 32 that moves the base 31. The container moving device 30 is attached, for example, to the main frame 3.

[0024] The base 31 is configured to be able to move horizontally and vertically. The base drive unit 32 moves the container B, which is held or placed on the base 31, between a first position P1 located below the first robot hand 15A and a second position P2 located below the second robot hand 15B. When the container B is in the first position P1, the base drive unit 32 moves the container B upward to bring it closer to the gripping part 20 of the first robot hand 15A. This allows the gripping part 20 to grip an item from the group of items X inside the container B.

[0025] Here, when each gripping part 20 is inserted into the food, depending on the properties of the item, each gripping part 20 may push the food aside, preventing the item from getting between the gripping parts 20, thus making it impossible to grip the appropriate amount of item. Even if the gripping parts 20 are inserted into a container B containing an elastic item (for example, dried squid, which is about 1 cm wide and 10 cm long), the entire item may simply sink, making it impossible to grip the appropriate amount of item. Therefore, the gripping parts 20 may be inserted into the item while the gripping parts 20 or container B is gently shaken. This makes it easier for the item to get between the gripping parts 20, making it possible to grip the appropriate amount of item.

[0026] When the amount of items X contained inside container B decreases, the container B with the reduced amount of items X inside is replaced by a new container B (containing a larger amount of items X) by a person or machine.

[0027] The base drive unit 32 moves the base 31 vertically and horizontally using a motor and fluid pressure as drive sources. The base drive unit 32 has a drive box 33, a first main arm section 34A and a second main arm section 34B which can swing around two parallel first axes L1 and second axes L2 provided in the drive box 33, and a first sub-arm section 35A and a second sub-arm section 35B which are rotatably connected to the ends of the first and second main arm sections 35A and 34B, respectively. The ends of the first sub-arm section 35A and the second sub-arm section 35B are rotatably connected to the rear end of the base 31. The first main arm section 34A and the second main arm section 34B each swing to face any direction by a motor (not shown) housed in the drive box 33. The base drive unit 32 has a two-axis parallel link mechanism with these configurations.

[0028] The base 31 is movable while maintaining a horizontal posture to a first position P1, a position closer to the first robot hand 15A than the first position P1, a second position P2, and a position closer to the second robot hand 15B than the second position P2. However, the configuration is not limited to the above, and the base drive unit 32 may have a left-right movement mechanism for moving the base 31 in the left-right direction and a vertical movement mechanism for moving the base 31 in the vertical direction. The position of the container B can also be adjusted by such a two-axis drive mechanism.

[0029] The base drive unit 32 raises the base 31 on which the container B is placed or held, bringing the container B and the group of articles X closer to the robot hand 15. The base drive unit 32 lowers the base 31 on which the container B is placed or held, moving the container B and the group of articles X away from the robot hand 15. The base drive unit 32 inserts the gripping claws 21 into the group of articles X contained in (placed on) the container B, and then separates the gripping claws 21 that have gripped the articles from the container B.

[0030] The discharge chute 50 guides the articles supplied from above downwards for discharge. The article weighing device 1 of this embodiment is provided with two discharge chutes 50, 50. The two discharge chutes 50, 50 are, for example, identical in size and shape and are arranged side by side. In the following description, the discharge chute 50 located on the left side in the front view of Figure 1 may be referred to as the first discharge chute 50A, and the discharge chute 50 located on the right side in the front view may be referred to as the second discharge chute 50B. However, when describing common configurations and functions, the name simply "discharge chute 50" is used.

[0031] The discharge chute 50 is a funnel-shaped component. The discharge chute 50 is positioned below the robot hand 15. Specifically, the first discharge chute 50A is positioned below the first robot hand 15A, and the second discharge chute 50B is positioned below the second robot hand 15B. The first position P1 of container B is located between the first robot hand 15A and the first discharge chute 50A, and the second position P2 of container B is located between the second robot hand 15B and the second discharge chute 50B.

[0032] The first discharge chute 50A receives the item that the gripping part 20 of the first robot hand 15A releases its grip on and discharges (drops) when the container B is in the second position P2, and discharges it outside the item weighing device 1. Similarly, the second discharge chute 50B receives the item that the gripping part 20 of the second robot hand 15B releases its grip on and discharges (drops) when the container B is in the first position P1, and discharges it outside the item weighing device 1.

[0033] The control unit 70 controls the operation of various components of the item weighing device 1. The control unit 70 is configured as a computer device including a processor such as a CPU, memory such as ROM and RAM, storage, and communication devices. The control unit 70 can perform various functions through the cooperation of hardware such as the CPU, RAM, and ROM and software such as programs.

[0034] The control unit 70 performs combination calculations based on the weight values ​​of the items gripped by the gripping units 20. The combination calculation is a process of finding combinations of weight values ​​in which the sum of the weight values ​​of the items gripped by each of the gripping units 20 falls within the target weight range. First, the control unit 70 acquires each weight value. Next, based on the result of the combination calculation, the control unit 70 selects the gripping unit 20 corresponding to the combination of weight values ​​that falls within the target weight range. The control unit 70 then performs control to release the grip of the selected gripping unit 20 and discharge the item. The control unit 70 releases the grip of the item from the gripping unit 20 above the discharge chute 50, causing the item to fall into the discharge chute 50.

[0035] The target weight range is a predetermined range of weights that includes the target weight (target weight or ideal weight). For example, the lower limit of the target weight range is 100% of the target weight, and the upper limit is 110% or 105% of the target weight.

[0036] The control unit 70 performs a first combination weighing to select a combination of weight values ​​that falls within a first target weight range, and executes a first process to calculate the number of weight value combinations based on the first combination weighing. If the number of weight value combinations based on the first combination weighing satisfies a set value (for example, 3), it releases the gripping unit 20 from the item corresponding to the combination selected by the first combination weighing.

[0037] Furthermore, if the number of weight value combinations based on the first combination weighing does not meet a set value (for example, 3), the control unit 70 performs a second combination weighing to select weight value combinations so that the second target weight range is an expanded version of the first target weight range, and then performs a second process to calculate the number of weight value combinations based on the second combination weighing. The second target weight range is, for example, a range expanded by 5% to 10% from the first target weight range. For example, the lower limit of the second target weight range is the same as the lower limit of the first target weight range.

[0038] When the number of weight value combinations based on the second combination weighing satisfies a set value (for example, 3), the control unit 70 releases the grip of the article by the gripping unit 20 corresponding to the combination selected by the second combination weighing.

[0039] The control unit 70 switches between a gripping state in which the gripping unit 20 grips an item and a discharge state in which the gripped item is discharged. The control unit 70 moves the hand drive unit 11 and the base drive unit 32 to bring the gripping unit 20 closer to the container B. The control unit 70 controls the gripping member drive mechanism 22 to put the gripping unit 20 into a gripping state and causes some of the items of the group of items X placed in the container B to be gripped by the gripping claws 21 of each gripping unit 20. The control unit 70 controls the gripping member drive mechanism 22 to release the grip of the item by the gripping unit 20, thereby discharging (dropping) the item into the discharge chute 50.

[0040] Furthermore, the control unit 70 alternately performs the following actions: gripping of the article placed on container B by the multiple gripping units 20 constituting the first robot hand 15A (hereinafter, the multiple gripping units 20 constituting the first robot hand 15A will be referred to as the "first gripping unit 20") and gripping by the multiple gripping units 20 constituting the second robot hand 15B (hereinafter, the multiple gripping units 20 constituting the second robot hand 15B will be referred to as the "second gripping unit 20"). Furthermore, the control unit 70 alternately performs the following actions: combined weighing of the article gripped by the first gripping unit 20 and release of the gripping of the article by the gripping unit 20 corresponding to the selected combination; and combined weighing of the article gripped by the second gripping unit 20 and release of the gripping of the article by the gripping unit 20 corresponding to the selected combination.

[0041] Next, the flow of combination weighing performed in the item weighing device 1 of this embodiment will be explained, mainly with reference to Figure 3. The control unit 70 performs a first combination weighing to select a combination of weight values ​​so that it falls within a first target weight range, and calculates the number of weight value combinations based on the first combination weighing (step S1). Next, the control unit 70 determines whether the number of weight value combinations based on the first combination weighing satisfies a set value (for example, 3) (step S2). Here, if the control unit 70 determines that the number of weight value combinations based on the first combination weighing satisfies the set value (S2: YES), it starts releasing the grip of the item by the gripping unit 20 corresponding to the weight value combination based on the first combination weighing. For example, if there are 3 sets of weight value combinations based on the first combination weighing, the control unit 70 releases the grip of the item by the gripping unit 20 one set at a time (step S7).

[0042] If the control unit 70 determines that the number of weight value combinations based on the first combination weighing does not meet the set value (S2:NO), it suspends the release of the gripping unit 20 from the article corresponding to the weight value combinations based on the first combination weighing (step S3). Next, the control unit 70 performs a second combination weighing to select weight value combinations that result in a second target weight range, which is an expanded version of the first target weight range, and calculates the number of weight value combinations based on the second combination weighing (step S4). Next, the control unit 70 determines whether the number of weight value combinations based on the second combination weighing meets the set value (for example, 3) (step S5). Here, if the control unit 70 determines that the number of weight value combinations based on the second combination weighing does not meet the set value (S5:NO), it starts releasing the gripping unit 20 from the article corresponding to the weight value combinations based on the first combination weighing. For example, if there are 3 sets of weight value combinations based on the first combination weighing, the control unit 70 releases the gripping unit 20 from the article one set at a time (step S7).

[0043] Here, if the control unit 70 determines that the number of weight value combinations based on the second combination weighing satisfies the set value (S5: YES), it starts releasing the grip of the article by the gripping unit 20 corresponding to the weight value combination based on the second combination weighing. For example, if there are 3 sets of weight value combinations based on the second combination weighing, the control unit 70 causes the gripping unit 20 to release the grip of the article one set at a time (step S6).

[0044] The effects and advantages of the article weighing device 1 of the above embodiment will now be explained. In the article weighing device 1 of the above embodiment, the number of combinations of weight values ​​based on the first combination weighing is calculated, and based on the number of combinations of weight values ​​based on the first combination weighing, the gripping part 20 corresponding to the combination selected by the first combination weighing is released. This makes it possible to expand the range of the target weight range as needed, thereby avoiding unnecessary expansion of the target weight range. As a result, a decrease in production capacity can be suppressed without unnecessarily expanding the target weight range.

[0045] In the above embodiment, the control unit 70 of the item weighing device 1 performs a second combination weighing only when the number of combinations of weight values ​​based on the first combination weighing does not meet a set value. This allows processing to be performed without delay, even when a control unit 70 with low processing capacity is used.

[0046] In the above embodiment, the control unit 70 of the article weighing device 1 releases the grip of the article by the gripping unit 20 corresponding to the combination selected by the first combination weighing if the number of weight value combinations based on the first combination weighing does not meet the set value and the number of weight value combinations based on the second combination weighing does not meet the set value. As a result, if both the number of weight value combinations based on the first combination weighing and the number of weight value combinations based on the second combination weighing, which expands the target weight range, do not meet the set value, the grip of the article by the gripping unit 20 corresponding to the combination selected by the first combination weighing before the target weight range was expanded can be released. As a result, even if the processing capacity decreases, the target weight range can be avoided from being unnecessarily expanded.

[0047] In the article weighing device 1 of the above embodiment, the control unit 70 alternately performs gripping by the first gripping unit 20 and gripping by the second gripping unit 20, and alternately performs combined weighing of the articles gripped by the first gripping unit 20 and release of the articles gripped by the gripping unit 20 corresponding to the selected combination, and combined weighing of the articles gripped by the second gripping unit 20 and release of the articles gripped by the gripping unit 20 corresponding to the selected combination. With this configuration, the rate at which articles within the target weight range or an expanded target weight range can be supplied to the downstream process at regular intervals can be increased.

[0048] This point will be explained using Figures 4 and 5. As shown in Figure 4, in the article weighing device 1 of the above embodiment, it takes a first predetermined time (e.g., 4.5 seconds) for the first robot hand 15A and the second robot hand 15B to grasp the article and complete the combined weighing. In addition, in the article weighing device 1 of the above embodiment, it takes a second predetermined time (e.g., 1.5 seconds) for the first robot hand 15A and the second robot hand 15B to release the grip of the article by the gripping part 20 corresponding to the selected combination. In other words, the first robot hand 15A and the second robot hand 15B can discharge articles within the target weight range or expanded weight range into the discharge chute 50 at intervals of the second predetermined time (e.g., 1.5 seconds). The first predetermined time is set to be three times the second predetermined time.

[0049] In the item weighing device 1 having such processing capabilities, gripping by the first gripping unit 20 and gripping by the second gripping unit 20 are performed alternately at first predetermined time intervals (for example, 4.5 seconds). When the first gripping unit 20 performs the operation of gripping an item onto container B, the combined weighing of the item gripped by the second gripping unit 20 and the release of the gripping of the item by the gripping unit 20 corresponding to the selected combination are performed in parallel. Similarly, when the second gripping unit 20 performs the operation of gripping an item onto container B, the combined weighing of the item gripped by the first gripping unit 20 and the release of the gripping of the item by the gripping unit 20 corresponding to the selected combination are performed in parallel.

[0050] As explained in the flowchart shown in Figure 3, in this embodiment, the grip of the article by the first gripping unit 20 (or second gripping unit 20) corresponding to the selected combination is released only when the number of weight value combinations based on the first combination weighing (or second combination weighing) satisfies a set value (e.g., 3). The release of the article by the first gripping unit 20 and the release of the article by the second gripping unit 20 are performed three times each at intervals of a second predetermined time (e.g., 1.5 seconds). Since the first predetermined time is set to be three times the second predetermined time, even if the target of the release of the article is switched between the first gripping unit 20 and the second gripping unit 20, as shown in Figure 4, the article continues to be discharged into the discharge chute 50 at intervals of the second predetermined time (e.g., 1.5 seconds). In other words, articles of weight within the first target weight range or the second target weight range are continuously discharged into the discharge chute 50 at regular intervals.

[0051] In the case of the article weighing device 1 of this embodiment, if the grip of an article by the first gripping part 20 (or second gripping part 20) corresponding to the selected combination is released regardless of the number of combinations of weight values ​​based on the first combination weighing (or second combination weighing), then, as shown in Figure 5, for example, articles weighing within the first target weight range or the second target weight range will not be continuously discharged at regular intervals. For example, if the release of the grip of an article by the second gripping part 20 can only be performed twice, as shown in Figure 5, then articles weighing within the first target weight range or the second target weight range will not be continuously discharged into the discharge chute 50 at regular intervals.

[0052] When items weighing within the first or second target weight range are discharged into the discharge chute 50 at regular intervals, containers for holding the items only need to be transported at regular intervals. Therefore, when storing items weighing within the first or second target weight range in containers, it is not necessary to perform synchronous control to transport the containers in accordance with the discharge of the items, thus simplifying the device configuration.

[0053] Although one embodiment has been described above, one aspect of the present invention is not limited to the above embodiment. Various modifications are possible without departing from the spirit of the invention.

[0054] In the above embodiment of the weighing device 1, the control unit 70 has been described as performing a second combination weighing operation to select a combination of weight values ​​to fall within the second target weight range only when it determines that the number of combinations of weight values ​​based on the first combination weighing operation does not meet the set value. However, the device is not limited to this example. For example, the control unit 70 may perform both a first combination weighing operation to select a combination of weight values ​​to fall within the first target weight range and a second combination weighing operation to select a combination of weight values ​​to fall within the second target weight range. Modifications in this case will be explained mainly with reference to Figure 6.

[0055] The control unit 70 performs a first combination weighing to select a combination of weight values ​​so that it falls within the first target weight range, and calculates the number of weight value combinations based on the first combination weighing (step S11). Next, regardless of whether the number of weight value combinations based on the first combination weighing is greater than or equal to a set value, the control unit 70 performs a second combination weighing to select a combination of weight values ​​so that it falls within the second target weight range, which is an expanded version of the first target weight range, and calculates the number of weight value combinations based on the second combination weighing (step S12).

[0056] Next, the control unit 70 determines whether the number of weight value combinations based on the first combination weighing satisfies a set value (for example, 3) (step S13). If the control unit 70 determines that the number of weight value combinations based on the first combination weighing satisfies the set value (S3: YES), it starts releasing the grip of the article by the gripping unit 20 corresponding to the weight value combination based on the first combination weighing. For example, if there are 3 sets of weight value combinations based on the first combination weighing, the control unit 70 releases the grip of the article by the gripping unit 20 one set at a time (step S15).

[0057] If the control unit 70 determines that the number of weight value combinations based on the first combination weighing does not meet the set value (S13:NO), it determines whether the number of weight value combinations based on the second combination weighing meets the set value (for example, 3) (step S14). Here, if the control unit 70 determines that the number of weight value combinations based on the second combination weighing does not meet the set value (S14:NO), it starts releasing the grip of the article by the gripping unit 20 corresponding to the weight value combination based on the first combination weighing. For example, if there are 3 sets of weight value combinations based on the first combination weighing, the control unit 70 releases the grip of the article by the gripping unit 20 one set at a time (step S15).

[0058] Here, if the control unit 70 determines that the number of weight value combinations based on the second combination weighing satisfies the set value (S14: YES), it starts releasing the grip of the article by the gripping unit 20 corresponding to the weight value combination based on the second combination weighing. For example, if there are 3 sets of weight value combinations based on the second combination weighing, the control unit 70 releases the grip of the article by the gripping unit 20 one set at a time (step S16).

[0059] Even with the item weighing device 1 controlled by the modified example described above, the range of the target weight can be expanded as needed, similar to the item weighing device 1 controlled by the embodiment described above, thus avoiding unnecessary expansion of the target weight range. As a result, a decrease in production capacity can be suppressed without unnecessarily expanding the target weight range.

[0060] In the item weighing device 1 controlled by the modified example described above, the control unit 70 performs a second combination weighing, selecting a combination of weight values ​​to create a second target weight range which is an expanded first target weight range, and calculates the number of weight value combinations based on the second combination weighing, regardless of the calculation result of the number of weight value combinations based on the first combination weighing. In this configuration, the control unit 70 can perform the first combination weighing and the second combination weighing simultaneously.

[0061] In the above embodiment, an example was given in which the gripping part 20 grips an article by moving the base 31 to bring the container B closer to the robot hand 15. However, instead of this configuration, a configuration may be adopted in which the gripping part 20 grips an article by moving (for example, lowering) the robot hand 15 or the gripping part 20 to bring it closer to the container B. In that case, the robot hand 15 or the gripping part 20 is provided with an appropriate known moving mechanism. Also, by moving (for example, raising) the robot hand 15 or the gripping part 20, the gripping claws 21 that are gripping the article can be separated from the container B.

[0062] The robot hand may have only one gripping section 20.

[0063] Each gripping section 20 may have three, four, or five gripping claws 21. Each gripping claw may have six or more gripping claws 21. Increasing the number of claws allows for gripping heavier items and combining them for weighing. [Explanation of Symbols]

[0064] 1...Item weighing device, 15...Robot hand, 15A...First robot hand, 15B...Second robot hand, 17...Weighing device (weighing section), 20...Gripping section, 21...Gripping claws, 30...Container moving device, 50...Discharge chute (discharge section), 50A...First discharge chute, 50B...Second discharge chute, 70...Control unit, B...Container (placement section), X...Group of items.

Claims

1. A mounting section on which the group of items is placed, Multiple gripping units that grip some of the articles from the group of articles placed on the mounting unit and release the gripping of the articles to discharge them to the discharge unit, A weighing unit that measures the weight of the article gripped by each of the plurality of gripping units, The system includes a control unit which performs combination weighing, selecting a combination of weight values ​​such that the sum of the multiple weight values ​​weighed by the weighing unit and associated with each of the multiple gripping units falls within a preset target weight range, and releases the gripping of the article by the gripping unit corresponding to the selected combination, The control unit, A first combination weighing is performed to select a combination of weight values ​​that falls within a first target weight range, and a first process is executed to calculate the number of combinations of weight values ​​based on the first combination weighing. An article weighing device that, when the number of combinations of weight values ​​based on the first combination weighing satisfies a set value, releases the gripping portion of the article corresponding to the combination selected by the first combination weighing.

2. If the number of combinations of weight values ​​based on the first combination weighing does not satisfy the set value, the control unit performs a second combination weighing to select combinations of weight values ​​so that the range of the first target weight range is expanded to a second target weight range, and then performs a second process to calculate the number of combinations of weight values ​​based on the second combination weighing. The article weighing device according to claim 1, wherein when the number of combinations of weight values ​​based on the second combination weighing satisfies the set value, the gripping portion corresponding to the combination selected by the second combination weighing releases the grip of the article.

3. The weighing apparatus for articles according to claim 1, wherein the control unit performs a second combination weighing to select a combination of weight values ​​so that the range of the first target weight range becomes a second target weight range, and performs a second process to calculate the number of combinations of weight values ​​based on the second combination weighing, regardless of the result of calculating the number of combinations of weight values ​​based on the first combination weighing.

4. The article weighing device according to claim 2 or 3, wherein the control unit releases the gripping portion of the article corresponding to the combination selected by the first combination weighing if the number of combinations of weight values ​​based on the first combination weighing does not meet a set value and the number of combinations of weight values ​​based on the second combination weighing does not meet a set value.

5. The plurality of gripping parts include a plurality of first gripping parts arranged in a first region and a plurality of second gripping parts arranged in a second region, The control unit alternately performs gripping of the article placed on the aforementioned mounting unit by the plurality of first gripping units and gripping by the plurality of second gripping units. An article weighing device according to any one of claims 1 to 3, which alternately performs the following: the combined weighing of articles held by a plurality of first gripping parts and the release of the gripping parts corresponding to the selected combination of articles; and the combined weighing of articles held by a plurality of second gripping parts and the release of the gripping parts corresponding to the selected combination of articles.

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