Patent Description:
Patent Document <NUM> (<CIT>) discloses, as a weight-measuring and distributing device, a device having gripping means to grip and eliminate a portion of a product, and a plurality of gathering units individually provided with weight-measuring means to record the weight of the portion of the product.

The device is furthermore provided with distribution means, and a computer programmed in advance for the purpose of a prescribed total weight, the device measuring the weight of articles gripped by the gripping means using the weight-measuring means, and performing combinatorial weighing on the basis of measured weight values.

<CIT> discloses a robot for securely conveying long and soft food such as pasta to a predetermined position. The robot includes a base, a first robot arm and a second robot arm connected to the base, a robot hand which is arranged on the first robot arm and is structured so as to hold the food, and an end effector which is arranged on the second robot arm. The end effector is structured so as to support a longitudinal intermediate part of the food in a state that the food is suspended from an end part of the robot hand. The food is held by the robot hand and the food is conveyed while being supported by the end effector at the longitudinal intermediate part of the food.

However, when the articles are articles that readily spill out, such as food ingredients, there is a concern that food ingredients could drop from gripping means that are not participating in a combination; in such instances, the food ingredients that dropped could mix with combinatorially weighed food ingredients and reduce weighing precision.

Thus, an object of the present invention is to provide a weighing device in which dropping of articles from gripping means and reductions in weighing precision are suppressed.

According to the invention, there are provided weighing devices in accordance with to the appended claims.

A weighing device according to an aspect of the present invention is a weighing device that weighs articles of an article group accommodated in a container, the weighing device comprising a robot arm, a gripping unit, a weighing unit, and a control unit. The gripping unit is attached to a distal end of the robot arm, and grips a portion of the articles from the article group within the container. The weighing unit measures a weight value of the articles gripped by the gripping unit. The control unit controls operation of the gripping unit. Moreover, when a prescribed condition is fulfilled by at least one of an operation state of the gripping unit and a weighing result from the weighing unit, the articles gripped by the gripping unit are returned to the container by the control unit without said articles being discharged to a target discharge destination.

In this weighing device, performing a control in which, "when a prescribed condition is fulfilled articles gripped by a gripping unit are returned to a container without being discharged to a target discharge destination" avoids a situation where the gripping unit operates while still holding "articles that are not to be discharged. " As a result, dropping of articles from the gripping unit and reductions in weighing precision are suppressed.

A weighing device according to a second aspect of the present invention is the weighing device according to the first aspect, wherein the weighing device furthermore comprises a plurality of the gripping units, and a plurality of the weighing units. When a prescribed condition is fulfilled by at least one of the operation state of any gripping unit from among the plurality of gripping units and the weighing result from the weighing unit corresponding to said gripping unit, the articles gripped by the gripping unit fulfilling the prescribed condition are returned to the container by the control unit without said articles being discharged to the discharge destination.

A weighing device according to a third aspect of the present invention is the weighing device according to the first aspect, wherein the weighing device furthermore comprises a plurality of the gripping units, a plurality of the weighing units, and a discharge chute. The articles discharged from the gripping units are received in and then discharged from the discharge chute. The control unit carries out a combination calculation using the weight value of the articles gripped by each of the plurality of gripping units, and selects a combination for which a preset target weight value is reached. Furthermore, when a prescribed condition is fulfilled by the weighing result from a weighing unit corresponding to at least one gripping unit from among the plurality of gripping units, the articles gripped by the gripping unit fulfilling the prescribed condition are returned to the container by the control unit, whereupon articles gripped by gripping units that do not fulfill the prescribed condition are discharged to the discharge chute by the control unit.

The weighing device according to a fourth aspect of the present invention is the weighing device according to the first aspect or the second aspect, wherein the prescribed condition includes the weight value of the articles weighed by the weighing unit not being a preset target weight value.

In this weighing device, a situation where the gripping unit operates while still holding "articles for which the weight value is not the target weight value" is avoided. As a result, dropping of articles from the gripping unit and reductions in weighing precision are suppressed. Furthermore, wasteful operation is eliminated, and production efficiency can be improved.

The weighing device according to a fifth aspect of the present invention is the weighing device according to the first aspect or the second aspect, wherein the prescribed condition includes an operating distance in an operation in which the articles are held by the gripping unit being greater than a prescribed range.

Here, "an operating distance in an operation in which the articles are held by the gripping unit being greater than a prescribed range" is specifically described. For example, when a gripping unit sandwiches and holds an article between a plurality of gripping members, a range bounded by a smallest inscribed circle with respect to the gripping members when an article that matches a lower-limit value of the target weight value is sandwiched, and by a smallest inscribed circle with respect to the gripping members when an article that matches an upper-limit value of the target weight value is sandwiched, is a prescribed range in which the target weight value is satisfied.

Therefore, the smallest inscribed circle with respect to the gripping members when an article that exceeds the upper-limit value of the target weight value is sandwiched is positioned further outward than the prescribed range as viewed from a circle center. Specifically, this signifies that a position (coordinates) reached by the gripping members is further outward than a position (coordinates) reached by gripping members sandwiching an article that matches the upper-limit value of the target weight value.

In such instances, it is assessed that "the operating distance in an operation in which the articles are held by the gripping unit is greater than a prescribed range.

However, if the gripping members are in a fully open state when the gripping operation starts, then the operating distance by which the gripping members are operated will be lower when the weight value of articles being gripped is greater than the target weight value than when articles having the target weight value are gripped. Thus, when the operating distance is conceived of as "displacement" with reference to the fully open state of the gripping members, "the operating distance in an operation in which the articles are held by the gripping unit being less than the prescribed range" signifies that the weight value of said articles is greater than the target weight value.

In this weighing device, the operating distance in an operation in which the articles are held by the gripping unit being greater than the prescribed range signifies that the weight value of said articles is not the target weight value. Thus, a situation where the gripping unit operates while still holding "articles for which the weight value is not the target weight value" is avoided. As a result, dropping of articles from the gripping unit and reductions in weighing precision are suppressed. Furthermore, wasteful operation is eliminated, and production efficiency can be improved.

The weighing device according to a sixth aspect of the present invention is the weighing device according to the first aspect or the second aspect, wherein the prescribed condition includes an operating distance in an operation in which the articles are held by the gripping unit being less than a prescribed range.

Here, "an operating distance in an operation in which the articles are held by the gripping unit being less than a prescribed range" is specifically described. For example, when a gripping unit sandwiches and holds an article between a plurality of gripping members, a range bounded by a smallest inscribed circle with respect to the gripping members when an article that matches a lower-limit value of the target weight value is sandwiched, and by a smallest inscribed circle with respect to the gripping members when an article that matches an upper-limit value of the target weight value is sandwiched, is a prescribed range in which the target weight value is satisfied.

Therefore, the smallest inscribed circle with respect to the gripping members when an article that is below the lower-limit value of the target weight value is sandwiched is positioned further inward than the prescribed range as viewed from a circle center. Specifically, this signifies that a position (coordinates) reached by the gripping members is further inward than a position (coordinates) reached by gripping members sandwiching an article that matches the lower-limit value of the target weight value.

In such instances, it is assessed that "the operating distance in an operation in which the articles are held by the gripping unit is less than a prescribed range.

However, if the gripping members are in a fully open state when the gripping operation starts, then the operating distance by which the gripping members are operated will be greater when the weight value of articles being gripped is less than the target weight value than when articles having the target weight value are gripped.

Thus, when the operating distance is conceived of as "displacement" with reference to the fully open state of the gripping members, "the operating distance in an operation in which the articles are held by the gripping unit being greater than the prescribed range" signifies that the weight value of said articles is less than the target weight value.

In this weighing device, the operating distance in an operation in which the articles are held by the gripping unit being less than the prescribed range signifies that the weight value of said articles is not the target weight value. Thus, a situation where the gripping unit operates while still holding "articles for which the weight value is not the target weight value" is avoided. As a result, wasteful operation is eliminated, and production efficiency can be improved.

The weighing device according to a seventh aspect of the present invention is the weighing device according to the fifth aspect or the sixth aspect, wherein the gripping units have at least two claws to grasp the articles. The operating distance is the degree to which the two claws open.

For example, a range bounded by a smallest inscribed circle with respect to the claws when an article that matches a lower-limit value of the target weight value is sandwiched, and by a smallest inscribed circle with respect to the claws when an article that matches an upper-limit value of the target weight value is sandwiched, is a prescribed range in which the target weight value is satisfied.

Therefore, the smallest inscribed circle with respect to the claws when an article that exceeds the upper-limit value of the target weight value is sandwiched is positioned further outward than the prescribed range as viewed from the circle center. Specifically, this signifies that a position (coordinates) reached by the claws is further outward than a position (coordinates) reached by claws sandwiching an article that matches the upper-limit value of the target weight value. In such instances, it is assessed that "the opening degree between the two claws is greater than the prescribed range.

Conversely, the smallest inscribed circle with respect to the claws when an article that is below the lower-limit value of the target weight value is sandwiched is positioned further inward than the prescribed range as viewed from the circle center. Specifically, this signifies that a position (coordinates) reached by the claws is further inward than a position (coordinates) reached by claws sandwiching an article that matches the lower-limit value of the target weight value. In such instances, it is assessed that "the opening degree between the two claws is less than the prescribed range.

However, if the two claws are in a fully open state when the gripping operation starts, then the operating distance by which the claws are operated will be lower when the weight value of articles being gripped is greater than the target weight value than when articles having the target weight value are gripped. Thus, when the operating distance is conceived of as "displacement" with reference to the fully open state of the claws, "the operating distance in an operation in which the articles are held by the claws being less than the prescribed range" signifies that the weight value of said articles is greater than the target weight value.

Moreover, if the two claws are in a fully open state when the gripping operation starts, then the operating distance by which the claws are operated will be greater when the weight value of articles being gripped is less than the target weight value than when articles having the target weight value are gripped.

Thus, when the operating distance is conceived of as "displacement" with reference to the fully open state of the claws, "the operating distance in an operation in which the articles are held by the claws being greater than the prescribed range" signifies that the weight value of said articles is less than the target weight value.

In this weighing device, the opening degree between the two claws being greater than the prescribed range signifies that the weight value of the articles gripped thereby is greater than the target weight value. Moreover, the opening degree between the two claws being less than the prescribed range signifies that the weight value of the articles gripped thereby is less than the target weight value. Thus, a situation where the gripping unit operates while still holding "articles for which the weight value is not the target weight value" is avoided. As a result, dropping of articles from the gripping unit and reductions in weighing precision are suppressed. Furthermore, wasteful operation is eliminated, and production efficiency can be improved.

The weighing device according to an eighth aspect of the present invention is the weighing device according to the third aspect, wherein the prescribed condition includes the weighing result not being selected for the combination for which the target weight value is reached.

In this weighing device, articles gripped by gripping units not selected for the combination are returned to the container, whereupon articles gripped by gripping units selected for the combination are discharged to the discharge chute. Therefore, articles gripped by gripping units not selected for the combination do not spill out from the gripping units and are not discharged to the discharge chute, and weighing precision can be improved.

The weighing device according to a ninth aspect of the present invention is the weighing device according to the eighth aspect, wherein when there is no combination for which the target weight value is reached, the control unit discharges all of the articles gripped by the gripping units to the container.

The weighing device according to a tenth aspect of the present invention is the weighing device according to any of the first to ninth aspects, wherein, when returning the articles gripped by the gripping unit to the container, the control unit causes the gripping unit and the container to move relative to each other.

In this weighing device, if articles are returned to the previous location at which the articles were grasped, it is not very likely that a suitable amount will be obtained when articles are subsequently grasped; therefore, moving the gripping unit and the container relative to each other and shifting the locations at which articles are returned raises the likelihood of grasping a suitable amount of articles.

The weighing device according to an eleventh aspect of the present invention is the weighing device according to any of the first to ninth aspects, wherein the container is capable of moving in horizontal first and second directions that are orthogonal to each other. When returning the articles gripped by the gripping unit to the container, the control unit causes the gripping unit and the container to move relative to each other in either of the first and second directions.

In this weighing device, the articles are returned to the container once the positional relationship between the gripping unit and the container is ascertained using planar coordinates, and therefore the articles can be returned in such a manner that the distribution of articles in the container is uniform.

The weighing device according to a twelfth aspect of the present invention is the weighing device according to any of the first to ninth aspects, wherein at least one of the gripping unit and the container is capable of rotating about a vertical axis. The control unit causes the gripping unit and the container to perform relative rotation by a prescribed angle in plan view.

In the weighing device according to the present invention, performing a control in which, "when a prescribed condition is fulfilled articles gripped by a gripping unit are returned to a container without being discharged to a target discharge destination" avoids a situation where the gripping unit operates while still holding "articles that are not to be discharged. " As a result, dropping of articles from the gripping unit and reductions in weighing precision are suppressed.

Embodiments of the present invention will be described while referring to the drawings. The embodiments described below are specific examples of the present invention, and are not intended to limit the technical scope of the present invention.

<FIG> is a schematic view of a weighing device <NUM>. <FIG> is a block diagram of the weighing device <NUM>. In <FIG>, the weighing device <NUM> extracts and discharges a portion of articles A from an article group A1, which is a collection of articles A.

Specifically, the weighing device <NUM> extracts and discharges a portion of the articles A from the article group A1 such that a weight reaches a target weight range. The articles A discharged by the weighing device <NUM> are, e.g., packaged in a bag or accommodated in a container, and then shipped as goods in steps following the weighing device <NUM>.

The weighing device <NUM> is provided with a robot arm <NUM>, a movable member <NUM>, a gripper <NUM>, a weighing unit <NUM>, a loading unit <NUM>, a loading unit driver <NUM>, a discharge chute <NUM>, and a control unit <NUM>. The control unit <NUM> carries out various calculations and controls the operation of each part of the weighing device <NUM>.

The article group A1 is loaded in the loading unit <NUM>. The article A is, e.g., a food product. Moreover, the article A may be, for example, spaghetti or other noodles, and/or a highly sticky food product such as a food product including a large amount of sugar.

The loading unit <NUM> is moved, by the loading unit driver <NUM>, between a first position at which the gripper <NUM> grips the article A of the article group A1 loaded into the loading unit <NUM>, and a second position at which the gripper <NUM> is not gripping the article A from the article group A1 loaded into the loading unit <NUM>.

Each gripper <NUM> has a gripping member <NUM> to grip the articles A. The gripper <NUM> is attached to the movable member <NUM>. In the present embodiment, a plurality of grippers <NUM> are attached to the movable member <NUM>.

The robot arm <NUM> moves the movable member <NUM> to which the grippers <NUM> are attached. The weighing unit <NUM> measures a weight value of the articles A gripped by each gripper <NUM>. The articles A for which gripping by the grippers <NUM> has been released are received in and then discharged from the discharge chute <NUM>.

The control unit <NUM> controls the operation of the various constituents of the weighing device <NUM> including the loading unit driver <NUM>, a gripping member driving mechanism <NUM>, and the robot arm <NUM>, and/or carries out a combination calculation, etc., that utilizes the weight values of the articles A weighed by the weighing unit <NUM>.

The control unit <NUM> controls the operation of the robot arm <NUM> to move the movable member <NUM> and bring the grippers <NUM> close to the loading unit <NUM> placed at the first position and loaded with the article group A1. The control unit <NUM> controls a gripping member driving mechanism <NUM> of each gripper <NUM>, and causes the gripping members <NUM> of each gripper <NUM> to grip a portion of the articles A of the article group A1 loaded in the loading unit <NUM>.

Each weighing unit <NUM> measures a weight value of the articles A gripped by the gripper <NUM> corresponding to the weighing unit <NUM> thereof. The control unit <NUM> carries out a combination calculation on the basis of the weight values of the articles A gripped by the grippers <NUM>, each weight value being measured by the respective weighing unit <NUM>.

The combination calculation is a process of finding a combination of weight values for which a total value thereof reaches a target weight range when the weight values of the articles A gripped by each of the grippers <NUM> are added together. On the basis of the result of the combination calculation, the control unit <NUM> causes the gripping members <NUM> of the grippers <NUM> corresponding to a combination of weight values for which the target weight range is reached to release gripping of the articles A from above the discharge chute <NUM> and thereby discharge the articles A of the target weight range from the discharge chute <NUM>.

<FIG> is a schematic perspective view of the robot arm <NUM>, the movable member <NUM>, the weighing unit <NUM>, and the grippers <NUM>. <FIG> is a schematic perspective view of the movable member <NUM>, the weighing unit <NUM>, and the grippers <NUM>. <FIG> is a bottom surface view in which the movable member <NUM> to which the grippers <NUM> are attached is viewed from the gripping-member <NUM> side of the grippers <NUM> (from below). <FIG> and <FIG> are bottom surface views of one gripper <NUM> of <FIG> as viewed from below the gripping members <NUM> of the one gripper <NUM>.

The movable member <NUM> is a member to which the gripper <NUM> is attached. In the present embodiment, a plurality of grippers <NUM> are attached to the movable member <NUM>. The movable member <NUM> is a frame supporting the grippers <NUM>. The movable member <NUM> is a member that is moved by the robot arm <NUM>.

Herein, the statement that "the gripper <NUM> is attached to the movable member <NUM>" does not represent only an aspect in which the gripper <NUM> is directly attached to the movable member <NUM>. Rather, this statement also includes an aspect in which the gripper <NUM> is attached to the movable member <NUM> via another member. In the present embodiment, the gripper <NUM> is attached to the movable member <NUM> via a sensor unit <NUM> of the weighing unit <NUM>, as shown in <FIG>.

The robot arm <NUM> is a device that supports the movable member <NUM>, and moves the movable member <NUM>. In the present embodiment, the robot arm <NUM> moves the movable member <NUM> along a single axis. Specifically, the robot arm <NUM> moves the movable member <NUM> up and down along a single axis extending in a vertical direction.

In the present embodiment, the robot arm <NUM> is an articulated robot like that illustrated in <FIG>. However, the type of the robot arm <NUM> is not limited to an articulated robot, and the robot <NUM> need only be a device that can move the movable member <NUM> in a prescribed direction.

Moreover, in place of the robot arm <NUM>, the weighing device <NUM> may have a cylinder that can move the movable member <NUM> in a prescribed direction. For example, the weighing device <NUM> may have, in place of the robot arm <NUM>, a cylinder that can move the movable member <NUM> along a single axis.

The gripper <NUM> is a device for gripping the article A. Each gripper <NUM> has a gripping member <NUM>, and a gripping member driving mechanism <NUM> as a driving mechanism to drive the gripping member <NUM>. The gripping member driving mechanism <NUM> drives the gripping member <NUM> using, for example, a motor and/or fluid pressure as a driving source.

In the present embodiment, the gripping member <NUM> is a rod-shaped or finger-shaped member, as shown in <FIG>. Each gripper <NUM> has a plurality (three in <FIG>) of gripping members <NUM>. The number and/or shape of the gripping members <NUM> depicted in <FIG>, etc., are merely examples, and can be changed, as appropriate.

In the present embodiment, when each gripper <NUM> is viewed from the gripping-member <NUM> side, the plurality of gripping members <NUM> are aligned and disposed in a circumferential direction of the gripper <NUM>, as shown in <FIG>. In addition, when each gripper <NUM> is viewed from the gripping-member <NUM> side, the plurality of gripping members <NUM> are aligned and disposed at generally equal intervals in the circumferential direction. Furthermore, the gripping members <NUM> can move in a radial direction of the gripper <NUM> when each gripper <NUM> is viewed from the gripping-member <NUM> side.

The gripper <NUM> causes gripping members <NUM> in a mutually separated state to shift radially inward through use of the gripping member driving mechanism <NUM> so that the gripping members <NUM> are in a mutually close state, as shown in <FIG> and <FIG>, and thereby holds an article A between a plurality of gripping members <NUM> to grip the article A.

Furthermore, the gripper <NUM> releases the gripping of the article A by causing the gripping members <NUM> that are in the mutually close state to shift radially outward through use of the gripping member driving mechanism <NUM> so that the gripping members <NUM> are in a mutually separated state.

As shown in <FIG>, <FIG>, and <FIG>, a plurality of grippers <NUM> are attached to the movable member <NUM>. Each gripper <NUM> is attached to the movable member <NUM> via a sensor unit <NUM> of the weighing unit <NUM>. The sensor unit <NUM> of the weighing unit <NUM> is disposed between the gripper <NUM> and the movable member <NUM> supporting the gripper <NUM>.

In the example illustrated in <FIG>, <FIG> and <FIG>, eleven grippers <NUM> are attached to the movable member <NUM>, but this is merely one example; the number of grippers <NUM> is not limited. The robot arm <NUM> moves the movable member <NUM> up and down, and the plurality of grippers <NUM> attached to the movable member <NUM> are thereby integrally moved up and down.

As shown in <FIG>, when the grippers <NUM> attached to the movable member <NUM> are viewed from the gripping-member <NUM> side, each gripper <NUM> has a substantially circular shape. In the present embodiment, when the grippers <NUM> attached to the movable member <NUM> are viewed from the gripping-member <NUM> side, the grippers <NUM> are disposed in a generally staggered shape. However, this arrangement is merely one example; the grippers <NUM> are not limited to being disposed in a staggered shape.

In the weighing device <NUM>, one weighing unit <NUM> is provided for each gripper <NUM>. The weighing unit <NUM> measures a weight value of an article A gripped by the gripping members <NUM> of the corresponding gripper <NUM>.

Each weighing unit <NUM> includes a sensor unit <NUM>, and a control unit (not shown). Each gripper <NUM> is attached to the movable member <NUM> via a sensor unit <NUM>, as shown in <FIG>. The sensor unit <NUM> includes a force sensor and an acceleration sensor. For example, a strain-gauge-type load cell is employed as the force sensor. Additionally, for example, a strain-gauge-type load cell and/or a MEMS type compact acceleration sensor is employed as the acceleration sensor.

When the gripper <NUM> in a state of gripping the article A is moved in association with movement of the movable member <NUM>, the control unit of the weighing unit <NUM> measures the mass of the article A gripped by the gripper <NUM>, on the basis of force and acceleration measured by the sensor unit <NUM>. Specifically, the control unit of the weighing unit <NUM> divides a force measured by the force sensor by the acceleration measured by the acceleration sensor, and thereby acquires the mass of the article A gripped by the gripper <NUM>.

However, the weighing unit <NUM> is not limited to a protocol in which the mass of the article A is measured on the basis of the force and acceleration measured when the gripper <NUM> moves. The weighing unit <NUM> may use a load cell, etc., to measure the weight of the article A gripped by the gripper <NUM> in a stationary state.

The article group A1 is loaded in the loading unit <NUM>. Specifically, the loading unit <NUM> includes an article group accommodation container <NUM> in which the articles A (article group A1) are accommodated. In the loading unit <NUM>, the article group A1 is loaded onto a loading surface 52a (here, a bottom surface of the article group accommodation container <NUM>).

The gripper <NUM> grips a portion of the articles A from the article group A1 accommodated in the article group accommodation container <NUM>. In the present embodiment, the article group accommodation container <NUM> is a rectangular parallelepiped container that is open at the top. The loading unit <NUM> is configured such that when the amount of articles A accommodated inside the article group accommodation container <NUM> decreases, a person or machine can exchange an article group accommodation container <NUM> having a decreased amount of articles A therein with a new article group accommodation container <NUM> (in which numerous articles A are accommodated).

Furthermore, instead of the loading unit <NUM> being configured such that the article group accommodation container <NUM> can be exchanged, the loading unit <NUM> may have an article supply mechanism for supplying articles A to the article group accommodation container <NUM>.

The loading unit <NUM> moves between a first position and a second position due to a loading unit driver <NUM>. The loading unit driver <NUM> moves the loading unit <NUM> using, for example, a motor and/or fluid pressure as a driving source. The first position is the position at which the gripper <NUM> grips the articles A of the article group A1 loaded in the loading unit <NUM>. The second position is the position at which the gripper <NUM> is not gripping the articles A from the article group A1 loaded in the loading unit <NUM>.

The loading unit driver <NUM> moves the loading unit <NUM> in a direction intersecting a direction of movement of the movable member <NUM>, between the first position and the second position. In the present embodiment, the loading unit driver <NUM> moves the loading unit <NUM> in a horizontal direction between the first position and the second position.

The first position of the loading unit <NUM> is, specifically, a position directly under the gripper <NUM>. When the loading unit <NUM> is in the first position, and the movable member <NUM> is moved by the robot arm <NUM> such that the gripper <NUM> approaches a prescribed position with respect to the loading unit <NUM>, the gripper <NUM> can grip an article A loaded in the loading unit <NUM>. Moreover, the first position of the loading unit <NUM> is a position directly above the discharge chute <NUM>.

Meanwhile, the second position of the loading unit <NUM> is a position separated from directly under the gripper <NUM>. In the present embodiment, the movable member <NUM> to which the grippers <NUM> are attached moves only in the vertical direction, and therefore when the loading unit <NUM> is in the second position, the grippers <NUM> cannot grip articles A loaded in the loading unit <NUM>. Moreover, the second position of the loading unit <NUM> is a position separated from directly above the discharge chute <NUM>.

The discharge chute <NUM> is a funnel-shaped member. The discharge chute <NUM> is disposed directly under the grippers <NUM>. In addition, when the loading unit <NUM> is positioned at the first position, the discharge chute <NUM> is disposed directly under the loading unit <NUM>. In other words, the loading unit <NUM> positioned in the first position is disposed between the grippers <NUM> and the discharge chute <NUM>.

Meanwhile, when the loading unit <NUM> is positioned at the second position, the loading unit <NUM> is not disposed between the grippers <NUM> and the discharge chute <NUM>.

The grippers <NUM> release the gripping, whereby the articles A supplied from the grippers <NUM> are discharged from the discharge chute <NUM> to outside the weighing device <NUM>. Specifically, when the loading unit <NUM> is positioned at the second position, articles A that are dropped when gripping by the grippers <NUM> is released are received in the discharge chute <NUM>, whereupon the articles A are discharged from the discharge chute <NUM> to outside of the weighing device <NUM>.

Although not illustrated, the control unit <NUM> has a CPU and/or memory such as ROM and/or RAM, etc. As shown in <FIG>, the control unit <NUM> is electrically connected to the robot arm <NUM>, the gripping member driving mechanisms <NUM>, the weighing units <NUM>, and the loading unit driver <NUM>.

The CPU executes a program stored in memory, and the control unit <NUM> thereby controls the operation of the various constituents of the weighing device <NUM> such as the robot arm <NUM>, the gripping member driving mechanisms <NUM>, and the loading unit driver <NUM>, and/or carries out, inter alia, a combination calculation which utilizes the weight values acquired by the weighing units <NUM> for the articles A.

The various functions of the control unit <NUM> need not be realized by software, and may be realized by hardware, or may be realized by cooperation between hardware and software.

The control unit <NUM> has, as control modes for the gripping member driving mechanism <NUM>, a first control mode, and a second control mode that differs from the first control mode.

In the first control mode, the control unit <NUM> controls the gripping member driving mechanism <NUM>, and causes the gripping members <NUM> to execute a first operation.

The first operation is an operation in which the gripping members <NUM> grip an article A and subsequently release the gripping of the article A. Here, the first operation is a series of operations whereby a plurality of gripping members <NUM> in mutually separated positions as illustrated in <FIG> shift radially inward and move to mutually close positions as illustrated in <FIG>, after which the plurality of gripping members <NUM> return again to the mutually separated positions as illustrated in <FIG>.

In the second control mode, the control unit <NUM> controls the gripping member driving mechanism <NUM>, and causes the gripping members <NUM> to execute a second operation. The second operation is an operation in which the gripping members <NUM> remove adhering matter adhering to the gripping members <NUM>.

Adhering matter is, for example, the article A itself, and/or a sticky substance, etc., included in the article A. For example, if the article A is spaghetti, the adhering matter may be noodles or ingredients and/or spaghetti sauce, etc..

By providing the control unit <NUM> with the second control mode as a control mode of the gripping member driving mechanism <NUM>, effects like that described below are obtained.

The weighing unit <NUM> corresponding to the gripper <NUM> acquires, as the weight of the article A, not only the weight of the article A gripped by the gripping members <NUM>, but also the weight of the adhering matter adhering to the gripping members <NUM>.

However, the adhering matter is not the article A gripped by the gripping member <NUM>, and therefore even if the gripping members <NUM> release the gripping of the article A, there is a concern that the adhering matter will not drop from the gripping members <NUM>.

Therefore, when the weight of the adhering matter adhering to the gripping member <NUM> increases, there is a concern that a deviation could occur between the weight of the article A discharged from the gripper <NUM>, and the weight of the article A weighed by the weighing unit <NUM> corresponding to the gripper <NUM> thereof.

Moreover, there is a concern that the adhering matter that has not dropped could drop suddenly into the discharge chute <NUM>, and that weighing precision could be impaired.

Furthermore, a state in which adhering matter remains adhered to the gripping members <NUM> for a long period of time is not preferable from a sanitary perspective. However, in the present embodiment, the control unit <NUM> has a second control mode as a control mode for the gripping member driving mechanism <NUM>, and the gripping members <NUM> carry out the second operation in which adhering matter adhering to the gripping members <NUM> is removed, and such a problem can thereby be alleviated.

The second operation of the gripping members <NUM> is an operation that differs from the first operation. The matter of the first operation and the second operation differing includes a case in which the mode of shifting of the gripping members <NUM> in the first operation and the mode of shifting of the gripping members <NUM> in the second operation differ.

The matter of the first operation and the second operation differing also includes a case in which the modes of shifting of the gripping members <NUM> are the same, but either the operating speed or the number of executions of the operation of the gripping members <NUM> differs between the first operation and the second operation.

A specific example of the second operation of the gripping members <NUM> is described below. The aspect of the second operation of the gripping members <NUM> given as one example described below may be combined, as appropriate, with an aspect of the second operation according to another example insofar as said aspects are not mutually contradictory.

For convenience of description, the positions of the plurality of gripping members <NUM> depicted in <FIG> are referred to as distant positions, and the positions of the plurality of gripping members <NUM> depicted in <FIG> are referred to as close positions.

The second operation of the gripping members <NUM> according to a first example is a series of operations in which, similar to the first operation, the plurality of gripping members <NUM> that are mutually separated and disposed at distant positions as in <FIG> are shifted radially inward and moved to close positions as illustrated in <FIG>, after which the gripping members <NUM> are returned again to the distant positions.

However, during the second operation, the average operating speed (hereinafter, referred to as an approaching speed) at which the gripping members <NUM> move from the distant positions to the close positions is greater than the approaching speed during the first operation. Additionally, or alternatively, the average operating speed (hereinafter, referred to as a separating speed) at which the gripping members <NUM> move from the close positions to the distant positions during the second operation is greater than the separating speed during the first operation.

In other words, during the second operation, movement of the gripping members <NUM> from the distant positions to the close positions, and/or movement of the gripping members <NUM> from the close positions to the distant positions, is performed in less time than in the first operation.

In particular, in the present embodiment, the approaching speed and the separating speed during the second operation are greater than the approaching speed and the separating speed, respectively, during the first operation. For example, the approaching speed and the separating speed of the gripping members <NUM> during the second operation are two or more times higher (more preferably, five or more times higher) than the approaching speed and the separating speed during the first operation.

Moreover, a maximum acceleration (hereinafter, referred to as an approaching acceleration) of the gripping members <NUM> when the gripping members <NUM> are moved from the distant positions to the close positions during the second operation is greater than the approaching acceleration during the first operation.

Additionally, or alternatively, a maximum deceleration (absolute value of the negative acceleration when decelerating, referred to hereinafter as an approaching deceleration) of the gripping members <NUM> when the gripping members <NUM> are moved from the distant positions to the close positions during the second operation is greater than the approaching deceleration during the first operation.

Additionally, or alternatively, the maximum acceleration (hereinafter, referred to as a separating acceleration) of the gripping members <NUM> when the gripping members <NUM> are moved from the close positions to the distant positions during the second operation is greater than the separating acceleration during the first operation. Additionally, or alternatively, a maximum deceleration (absolute value of the negative acceleration when decelerating, referred to hereinafter as an approaching deceleration) of the gripping members <NUM> when the gripping members <NUM> are moved from the close positions to the distant positions during the second operation is greater than the separating deceleration during the first operation.

For example, the approaching acceleration and the separating acceleration of the gripping members <NUM> during the second operation are two or more times greater (more preferably, five or more times greater) than the approaching acceleration and the separating acceleration during the first operation. Moreover, the approaching deceleration and the separating deceleration of the gripping members <NUM> during the second operation are two or more times greater (more preferably, five or more times greater) than the approaching deceleration and the separating deceleration during the first operation.

The second operation of the gripping members <NUM> of the first example is a series of operations in which, similar to the first operation, the plurality of gripping members <NUM> that are mutually separated and disposed at distant positions as in <FIG> are shifted radially inward and moved to close positions as illustrated in <FIG>, after which the gripping members <NUM> are returned again to the distant positions.

However, during the second operation, the number of times that the gripping members <NUM> are operated to move from the distant positions to the close positions or from the close positions to the distant positions is greater than during the first operation. For example, during the first operation, the series of operations in which the gripping members <NUM> are moved from the distant positions to the close positions and then again returned to the distant positions is executed one time, whereas during the second operation, the series of operations in which the gripping members are moved from the distant positions to the close positions and then again returned to the distant positions is executed a plurality of times. For example, during the second operation, the gripping members <NUM> execute the series of operations two or more times (more preferably, four or more times).

During the second operation, the gripping members <NUM> need not move in a range between the distant positions and the close positions as in the first operation. For example, the gripping members <NUM> may move within a narrower range during the second operation than during the first operation. For example, the movement amount of the gripping members <NUM> during the second operation may be set to <NUM>/<NUM> or less (more preferably, <NUM>/<NUM> or less) of the movement amount of the gripping members <NUM> during the first operation. Although not limited, the movement amount of the gripping members <NUM> during the second operation is set, for example, to <NUM>/<NUM> or more of the movement amount of the gripping members <NUM> during the first operation.

For example, in the second control mode, the control unit <NUM> combines the aspects of the first to third examples described above, and controls the gripping member driving mechanism <NUM> such that the gripping members <NUM> move back and forth in a narrow interval a plurality of times at a high speed. Through such control by the control unit <NUM>, the gripping members <NUM> oscillate at a high speed. Furthermore, by causing the gripping members <NUM> to undergo such an operation, removal of adhered matter adhered to the gripping members <NUM> is more easily facilitated.

The aspects of the first to third examples of the second operation described above need not all be simultaneously combined, and need only be combined as appropriate. For example, in another embodiment, the control unit <NUM> may control the gripping member driving mechanism <NUM> in the second control mode such that the gripping members <NUM> perform the same motion as that of the first operation (motion of moving from the distant positions to the close positions, and then again returning to the distant positions) only once at a high speed.

Operation of the weighing device <NUM> controlled by the control unit <NUM> will be described with reference to <FIG> and <FIG>. Although the weighing device <NUM> provided with a plurality of grippers <NUM> is described here as an example, the present invention can also be applied to a weighing device provided with a single gripper <NUM>.

<FIG> are schematic side views of the weighing device <NUM>, for explaining the operation of the weighing device <NUM> of <FIG>.

In <FIG>, depiction of the robot arm <NUM> that moves the movable member <NUM> is omitted. <FIG> is a flowchart for explaining the operation of the weighing device <NUM> according to a first embodiment.

<FIG> depicts an initial state before the grippers <NUM> grip the articles A. In <FIG>, the movable member <NUM> is disposed at a prescribed position such that the gripping members <NUM> of the grippers <NUM> are disposed outside of the article group accommodation container <NUM> of the loading unit <NUM>. The loading unit <NUM> is disposed at a first position directly under the grippers <NUM>. The gripping members <NUM> of each gripper <NUM> are disposed at the distant positions as in <FIG>.

When the weighing device <NUM> is running, the control unit <NUM> controls the robot arm <NUM> to move the movable member <NUM> vertically downward and bring the plurality of grippers <NUM> close to the loading unit <NUM> from the initial state.

Specifically, the control unit <NUM> controls the operation of the robot arm <NUM> to move the movable member <NUM> vertically downward so that the gripping members <NUM> of the grippers <NUM> are disposed at a prescribed position enabling the articles A inside the article group accommodation container <NUM> to be gripped (see <FIG>).

More specifically, the control unit <NUM> controls the operation of the robot arm <NUM> to move the movable member <NUM> vertically downward so that the gripping members <NUM> are at least partially inserted into the article group A1.

Next, in step S2, the control unit <NUM> controls the gripping member driving mechanism <NUM> of each gripper <NUM>, and causes the gripping members <NUM> to grip the articles A. Preferably, the control unit <NUM> causes a plurality of grippers <NUM> to simultaneously grip articles A. However, the present invention is not limited to this configuration, and the control unit <NUM> may cause the plurality of grippers <NUM> to grip articles A at different timings.

Next, with the plurality of grippers <NUM> gripping articles A, the control unit <NUM> controls the robot arm <NUM> to move the movable member <NUM> vertically upward such that the gripping members <NUM> of the grippers <NUM> are disposed outside of the article group accommodation container <NUM> of the loading unit <NUM> (see <FIG>). When the robot arm <NUM> moves the movable member <NUM> vertically upward, each weighing unit <NUM> measures the weight of the articles A gripped by the corresponding gripper <NUM>.

Next, the control unit <NUM> determines whether a prescribed condition for returning articles A gripped by the grippers <NUM> to the article group accommodation container <NUM> without discharging said articles A to the discharge chute <NUM> is fulfilled by at least one of the operation state of the grippers <NUM> and the weighing results from the weighing units <NUM>.

Here, the prescribed condition is described. A main purpose of this determination is to return to the article group accommodation container <NUM> before the article group accommodation container <NUM> is moved when the weight value of the articles A weighed by the weighing units <NUM> is not a preset target weight value, or is estimated not to be said target weight value, thereby preventing articles from erroneously being discharged to the chute <NUM>.

Thus, "fulfilling a prescribed condition" involves fulfilling at least one of the following:.

In particular, in the case of condition (<NUM>), the operating distance in an operation in which the articles A are held by the gripping members <NUM> being greater than a prescribed range signifies that the weight value of said articles A is greater than the target weight value.

<FIG> is a plan view of three gripping members <NUM> sandwiching a virtual article that matches a lower-limit value of the target weight value as viewed from a distal-end side of the gripping members <NUM>. In <FIG>, a circle C1 is a smallest inscribed circle with respect to the three gripping members <NUM>.

<FIG> is a plan view of three gripping members <NUM> sandwiching a virtual article that matches an upper-limit value of the target weight value as viewed from the distal-end side of the gripping members <NUM>. In <FIG>, a circle C2 is a smallest inscribed circle with respect to the three gripping members <NUM>. A range bounded by the circles C1 and C2 is a prescribed range R in which the target weight value is satisfied.

<FIG> is a plan view of three gripping members <NUM> sandwiching a virtual article that exceeds the upper-limit value of the target weight value as viewed from the distal-end side of the gripping members <NUM>. In <FIG>, a circle Ca is positioned further outward than the prescribed range R as viewed from a circle center. Specifically, this signifies that a position (coordinates) reached by the gripping members <NUM> is further outward than a position (coordinates) reached by gripping members sandwiching a virtual article that matches the upper-limit value of the target weight value.

In such instances, it is assessed that "the operating distance in an operation in which the articles are held by the gripping members <NUM> to hold the articles is greater than a prescribed range.

Moreover, in the case of condition (<NUM>), the operating distance in the operation in which the articles A are held by the gripping members <NUM> being less than the prescribed range signifies that the weight value of said articles is less than the target weight value.

<FIG> is a plan view of three gripping members <NUM> sandwiching a virtual article that is below the lower-limit value of the target weight value as viewed from the distal-end side of the gripping members <NUM>. In <FIG>, a circle Cb is positioned further inward than the prescribed range R as viewed from the circle center. Specifically, this signifies that a position (coordinates) reached by the gripping members <NUM> is further inward than a position (coordinates) reached by gripping members <NUM> sandwiching a virtual article that matches the lower-limit value of the target weight value.

In such instances, it is assessed that "the operating distance in an operation in which the articles A are held by the gripping members <NUM> is less than a prescribed range.

The assessment as to whether either of prescribed conditions (<NUM>) and (<NUM>) is fulfilled can be performed when step S2 is completed, and therefore, as illustrated in <FIG>, a step to assess whether either of prescribed conditions (<NUM>) and (<NUM>) is fulfilled may be provided between step S2 and step S3. A more detailed description is provided in section "(<NUM>) Modification of First Embodiment" below.

The control unit <NUM> proceeds to step S5 when it is determined that at least one of the operation state of the grippers <NUM> and the weighing results from the weighing units <NUM> fulfills the prescribed condition, but proceeds to step S6 when it is determined that neither fulfills the prescribed condition.

Next, the control unit <NUM> controls the gripping member drive mechanism <NUM> of grippers <NUM> that fulfill at least one of the prescribed conditions (<NUM>), (<NUM>), and (<NUM>) and causes said grippers <NUM> to release the gripping of the articles A (see <FIG>).

In other words, if there is a gripper <NUM> gripping an article A for which the weight value is not the target weight value, the control unit <NUM> controls the gripping member drive mechanism <NUM> of said gripper <NUM> and causes the gripper <NUM> to release the gripping of the article A.

The article A gripped by the gripper <NUM> is then dropped into the article group accommodation container <NUM> of the loading unit <NUM> positioned at the first position, and is reused as an article A of the article group A1. At this time, the first operation is completed for the gripping members <NUM> of grippers <NUM> that fulfilled the prescribed condition.

Moreover, immediately after gripping of the articles A has been released according to the first operation by the gripping members <NUM> of the grippers <NUM>, the control unit <NUM> controls the gripping member drive mechanisms <NUM> of said grippers <NUM>, and causes the gripping members <NUM> to execute the second operation. When the articles A are articles that do not readily adhere to the gripping members <NUM>, the second operation does not necessarily need to be executed.

The articles A in the gripper <NUM> that fulfills at least one of conditions (<NUM>), (<NUM>), and (<NUM>) being returned to the article group accommodation container <NUM> avoids a situation where the grippers <NUM> operate while still holding "articles A for which the weight value is not the target weight value. " As a result, dropping of articles from the grippers <NUM> and reductions in weighing precision are suppressed. Furthermore, wasteful operation is eliminated, and production efficiency can be improved.

Next, the control unit <NUM> controls the loading unit driver <NUM> to move the loading unit <NUM> from the first position to the second position (see <FIG>). Movement of the loading unit <NUM> to the second position brings about a state in which the loading unit <NUM> is not disposed between the grippers <NUM> and the discharge chute <NUM>.

Next, the control unit <NUM> controls the robot arm <NUM> to move the movable member <NUM> vertically downward and bring the plurality of grippers <NUM> close to the discharge chute <NUM> (see <FIG>).

Depending on the articles, it may be unnecessary to execute the "operation for bringing close. " In such cases, the articles may be dropped without moving the movable member <NUM> vertically downward.

Next, the control unit <NUM> causes the grippers <NUM> that did not fulfill any of the prescribed conditions (<NUM>), (<NUM>), and (<NUM>) in step <NUM> to release the gripping of the articles A, and discharges the articles A from the discharge chute <NUM> (see <FIG>). The first operation is completed at this time for the gripping members <NUM> of these grippers <NUM>.

When discharging of the articles A is completed, the control unit <NUM> controls the robot arm <NUM> to return the movable member <NUM> to an original position (see <FIG>).

Next, the control unit <NUM> also controls the loading unit driver <NUM> to return the loading unit <NUM> from the second position to the first position directly under the grippers <NUM> (see <FIG>).

The control unit <NUM> then determines whether there is a stop command. The control unit <NUM> stops the control when it is determined that there is a stop command, but returns to step S1 when it is determined that there is no stop command.

The operation of the weighing device <NUM> described here is merely one example, and can be changed, as appropriate, insofar as such change is not contradictory.

Moreover, for example, when the control unit <NUM> controls the robot arm <NUM> in a state in which the plurality of grippers <NUM> are gripping the articles A to cause the movable member <NUM> to move upward from the position depicted in <FIG> to the position depicted in <FIG>, the control unit <NUM> may control the robot arm <NUM> such that the movable member <NUM> is moved downward one or more times.

Moreover, moving the movable member <NUM> up and down as described above makes it possible for articles adhering to the gripping members <NUM> to be shaken off when the grippers <NUM> release gripping as well. Articles adhering to the gripping members <NUM> are articles that are not gripped by the gripping members <NUM> and that are likely to drop regardless of operation of the gripping members <NUM>. Moving the movable member <NUM> downward to shake off, in advance, articles adhering to the gripping members <NUM> brings the weight of the articles A weighed by the weighing unit <NUM> closer to the weight of the articles A gripped by the gripping members <NUM>, and makes it possible to improve the weighing precision.

In the weighing device <NUM>, when at least one of the operation state of the grippers <NUM> and the weighing results from the weighing units <NUM> fulfills any condition from among (<NUM>) the weight value of the articles A weighed by the weighing units <NUM> not being a preset target weight value, (<NUM>) the operating distance in an operation in which the articles A are held by the gripping members <NUM> being greater than a prescribed range, and (<NUM>) the operating distance in the operation in which the articles A are held by the gripping members <NUM> being less than the prescribed range, the articles A gripped by the grippers <NUM> are returned to the article group accommodation container <NUM> by the control unit <NUM> without said articles A being discharged to the discharge chute <NUM>.

The operating distance in the operation in which the articles A are held by the grippers <NUM> being greater than the prescribed range signifies that the weight value for said articles is greater than the target weight value.

For example, when articles A are sandwiched and held between three gripping members <NUM>, a range bounded by a smallest inscribed circle with respect to the three gripping members <NUM> when an article that matches a lower-limit value of the target weight value is sandwiched, and by a smallest inscribed circle with respect to the three gripping members <NUM> when an article that matches an upper-limit value of the target weight value is sandwiched, is a prescribed range R in which the target weight value is satisfied.

Therefore, the smallest inscribed circle with respect to the three gripping members <NUM> when an article A that exceeds the upper-limit value of the target weight value is sandwiched is positioned further outward than the prescribed range R as viewed from the circle center. Specifically, this signifies that a position (coordinates) reached by the gripping members <NUM> is further outward than a position (coordinates) reached by gripping members <NUM> sandwiching an article A that matches the upper-limit value of the target weight value.

In such instances, it is assessed that "the operating distance in an operation in which the articles A are held by the gripping members <NUM> is greater than the prescribed range R. " Thus, a situation where the grippers <NUM> operate while still holding "articles A for which the weight value is not the target weight value" is avoided.

Moreover, the operating distance in the operation in which the articles A are held by the grippers <NUM> being less than the prescribed range signifies that the weight value for said articles is less than the target weight value.

For example, the smallest inscribed circle with respect to the three gripping members <NUM> when an article A that is below the lower-limit value of the target weight value is sandwiched is positioned further inward than the prescribed range R as viewed from the circle center. Specifically, this signifies that a position (coordinates) reached by the gripping members <NUM> is further inward than a position (coordinates) reached by gripping members <NUM> sandwiching an article A that matches the lower-limit value of the target weight value.

In such instances, it is assessed that "the operating distance in an operation in which the articles A are held by the gripping members <NUM> is less than the prescribed range R.

Thus, a situation where the grippers <NUM> operate while still holding "articles A for which the weight value is not the target weight value" is avoided. As a result, dropping of articles A from the grippers <NUM> and reductions in weighing precision are suppressed. Furthermore, wasteful operation is eliminated, and production efficiency can be improved.

In the weighing device <NUM>, the operating distance in an operation in which the articles A are held by the grippers <NUM> is the degree to which the gripping members <NUM> open. The opening degree of the gripping members <NUM> being greater than a prescribed range signifies that the weight value of the articles A is greater than the target weight value. Moreover, the opening degree of the gripping members <NUM> being less than the prescribed range signifies that the weight value of the articles A is less than the target weight value.

<FIG> is a flowchart for explaining the operation of the weighing device <NUM> according to a modification of the first embodiment. In <FIG>, the difference between the modification and <FIG> is that a step S2a and a step S2b are inserted between step S2 and step S3.

Steps S1, S2, and S3 to S11 in <FIG> are the same as those in <FIG>, and these steps are therefore not described here. The newly inserted step S2a and step S2b are described here.

In step S2a, the control unit <NUM> determines whether a prescribed condition for returning articles A gripped by the grippers <NUM> to the article group accommodation container <NUM> without discharging said articles A to the discharge chute <NUM> is fulfilled by the operation state of the grippers <NUM>.

Here, "a prescribed condition being fulfilled" involves fulfilling at least one of the following, i.e., excluding (<NUM>) from among prescribed conditions (<NUM>) to (<NUM>) described in step S4 of the first embodiment:.

Because it is possible in step S2 to determine whether the operating distance in the operation in which the articles A are held by the gripping members <NUM> is greater than or less than the prescribed range, it is not necessary for the control unit <NUM> to move the movable member <NUM> vertically upward as in the first embodiment.

The control unit <NUM> proceeds to step S2b when it is determined that the operation state of the grippers <NUM> fulfills the prescribed condition (<NUM>) or (<NUM>), but proceeds to step S3 when it is determined that the operation state does not fulfill either prescribed condition.

Next, the control unit <NUM> controls the gripping member drive mechanism <NUM> of grippers <NUM> that fulfill at least one of the prescribed conditions (<NUM>) and (<NUM>), and causes said grippers <NUM> to release the gripping of the articles A (see <FIG>).

The articles A in the gripper <NUM> that fulfills at least one of conditions (<NUM>) and (<NUM>) being returned to the article group accommodation container <NUM> avoids a situation where the grippers <NUM> operate while still holding "articles A for which the weight value is not the target weight value. " As a result, dropping of articles from the grippers <NUM> and reductions in weighing precision are suppressed. Furthermore, wasteful operation is eliminated, and production efficiency can be improved.

In the first embodiment, a description was given presupposing a weighing device that grips fixed quantities. In a second embodiment, a combinatorial weighing device that carries out combinatorial weighing is described.

The structure of the weighing device according to the first embodiment is used without modification as the structure of the weighing device according to the second embodiment, and only controls thereof are varied. Therefore, the components are not described in detail here.

Operations of the weighing device <NUM> controlled by the control unit <NUM> are described while referring to <FIG> and <FIG>.

<FIG> is a flowchart for explaining the operation of the weighing device <NUM> according to the second embodiment.

In <FIG>, the movable member <NUM> is disposed at a prescribed position such that the gripping members <NUM> of the grippers <NUM> are disposed outside of the article group accommodation container <NUM> of the loading unit <NUM>. The loading unit <NUM> is disposed at a first position directly under the grippers <NUM>. The gripping members <NUM> of each gripper <NUM> are disposed at the distant positions as in <FIG>.

When the weighing device <NUM> is running, the control unit <NUM> controls the robot arm <NUM> to move the movable member <NUM> vertically downward and bring the plurality of grippers <NUM> closer to the loading unit <NUM>.

Next, the control unit <NUM> controls the gripping member drive mechanism <NUM> of each gripper <NUM> to cause the gripping members <NUM> to grip articles A. Preferably, the control unit <NUM> causes the plurality of grippers <NUM> to grip articles A simultaneously. However, the present invention is not limited to this configuration, and the control unit <NUM> may cause the plurality of grippers <NUM> to grip articles A at different timings.

The assessment as to whether either of prescribed conditions (<NUM>) and (<NUM>) is fulfilled in the first embodiment can be performed when step S102 is completed, and therefore a step to assess whether either of prescribed conditions (<NUM>) and (<NUM>) is fulfilled may be provided between step S102 and step S103. A more detailed description is provided in section "(<NUM>) Modification of Second Embodiment" below.

Next, the control unit <NUM> carries out a combination calculation using the weight values of the articles A gripped by the grippers <NUM>, each weight value being measured by the respective weighing unit <NUM>, and finds a combination of weight values for which a total value thereof reaches a target weight range.

Next, the control unit <NUM> determines whether there is a gripper <NUM> not selected for the combination among the grippers <NUM>.

The control unit <NUM> proceeds to step S106 when it is determined that there is a gripper <NUM> not selected for the combination, but proceeds to step S107 when it is determined that there is no gripper <NUM> not selected for the combination.

Next, if there is a gripper <NUM> for which the weight of the article A gripped thereby was not selected for the combination, the control unit <NUM> controls the gripping member drive mechanism <NUM> of said gripper <NUM> and causes the gripper <NUM> to release the gripping of the article A according to the first operation (see <FIG>).

The article A gripped by the gripper <NUM> is then dropped into the article group accommodation container <NUM> of the loading unit <NUM> positioned at the first position, and is reused as an article A of the article group A1. At this time, the first operation is completed for the gripping members <NUM> of grippers <NUM> not selected for the combination.

Next, immediately after gripping of the articles A has been released according to the first operation by the gripping members <NUM> of the grippers <NUM> caused to release the gripping of the articles A, the control unit <NUM> controls the gripping member driving mechanisms <NUM> of said grippers <NUM>, and causes the gripping members <NUM> to execute a second operation. When the articles A are articles that do not readily adhere to the gripping members <NUM>, the second operation does not necessarily need to be executed.

Next, on the basis of the result of the combination calculation, the control unit <NUM> causes the grippers <NUM> corresponding to the combination of weight values for which the target weight range is reached to release gripping of the articles A while above the discharge chute <NUM>, and discharges the articles A from the discharge chute A (see <FIG>). The first operation is completed at this time for the gripping members <NUM> of the grippers <NUM> selected for the combination.

When discharging of articles A is completed for all combinations of weight values for which the target weight range is reached, the control unit <NUM> controls the robot arm <NUM> to return the movable member <NUM> to an original position (see <FIG>).

The control unit <NUM> then determines whether there is a stop command. The control unit <NUM> stops the control when it is determined that there is a stop command, but returns to step S <NUM> when it is determined that there is no stop command.

In the weighing device <NUM>, if there is a gripper <NUM> for which the weight of the article A gripped thereby was not selected for the combination, the articles A gripped by the gripper <NUM> not selected for the combination are returned to the article group accommodation container <NUM>, whereupon the articles A gripped by the grippers <NUM> selected for the combination are discharged to the discharge chute <NUM>. As a result, articles A gripped by grippers <NUM> not selected for the combination do not spill out from the grippers <NUM> and are not discharged to the discharge chute <NUM>, and weighing precision can be improved.

In the weighing device <NUM>, when there is no combination for which the target weight value is reached, the control unit <NUM> discharges all of the articles gripped by the gripping units to the article group accommodation container <NUM>.

<FIG> is a flowchart for explaining the operation of the weighing device <NUM> according to a modification of the second embodiment. In <FIG>, the difference between the modification and <FIG> is that a step S102a and a step S102b are inserted between step S102 and step S103.

Steps S101, S102, and S103 to S112 in <FIG> are the same as those in <FIG>, and these steps are therefore not described here. The newly inserted step S102a and step S102b are described here.

In step S102a, the control unit <NUM> determines whether there is a gripper <NUM> not selected for the combination among the grippers <NUM>.

Here, "not selected for the combination among the grippers <NUM>" involves fulfilling at least one of the following, i.e., excluding (<NUM>) from among prescribed conditions (<NUM>) to (<NUM>) described in step S4 of the first embodiment:.

Because it is possible in step S102 to determine whether the operating distance in the operation in which the articles A are held by the gripping members <NUM> is greater than or less than the prescribed range at the point in time when the control unit <NUM> causes the gripping members <NUM> to grip the articles A, it is not necessary for the control unit <NUM> to move the movable member <NUM> vertically upward as in the first embodiment and the second embodiment.

The control unit <NUM> proceeds to step S102b when it is determined that the operation state of the grippers <NUM> fulfills the prescribed condition (<NUM>) or (<NUM>), but proceeds to step S103 when it is determined that the operation state does not fulfill either prescribed condition.

Next, the control unit <NUM> controls the gripping member drive mechanisms <NUM> of the grippers <NUM> fulfilling at least one of the prescribed conditions (<NUM>) and (<NUM>) to cause said grippers <NUM> to release gripping of the articles A (see <FIG>).

In other words, if there is a gripper <NUM> for which the weight of the article A gripped thereby was not selected for the combination, the control unit <NUM> controls the gripping member driving mechanism <NUM> of said gripper <NUM> to cause the gripper <NUM> to release gripping of the article A according to the first operation.

The article A gripped by the gripper <NUM> is then dropped into the article group accommodation container <NUM> of the loading unit <NUM> disposed at the first position, and is reused as an article A of the article group A1. At this time, the first operation is completed for the gripping members <NUM> of grippers <NUM> that fulfilled the prescribed condition.

The articles A in the gripper <NUM> that fulfills at least one of conditions (<NUM>) and (<NUM>) being returned to the article group accommodation container <NUM> avoids a situation where the grippers <NUM> operate while still holding "articles A not selected for the combination. " As a result, dropping of articles from the grippers <NUM> and reductions in weighing precision are suppressed. Furthermore, wasteful operation is eliminated, and production efficiency can be improved.

However, if the gripping members <NUM> are in a fully open state when the gripping operation starts, then the operating distance by which the gripping members <NUM> are operated will be greater when the weight value of articles being gripped is less than the target weight value than when articles having the target weight value are gripped.

Conversely, the operating distance by which the gripping members <NUM> are operated will be less when the weight value of articles being gripped is greater than the target weight value than when articles having the target weight value are gripped.

Thus, in cases where the gripping members <NUM> are in a fully open state when the gripping operation starts, and the operating distance is conceived of as "displacement" with reference to the fully open state of the gripping members <NUM>, "the operating distance in the operation in which the articles are held by the gripping units being greater than the prescribed range" signifies that the weight value of said articles is less than the target weight value. Moreover, "the operating distance in the operation in which the articles are held by the gripping units being less than the prescribed range" signifies that the weight value of said articles is greater than the target weight value.

Claim 1:
A weighing device (<NUM>) configured to weigh articles (A) of an article group accommodated in a container (<NUM>), the weighing device comprising:
a gripping unit (<NUM>) configured to grip a portion of the articles from the article group within the container (<NUM>);
a weighing unit (<NUM>) configured to measure a weight value of the articles gripped by the gripping unit (<NUM>); and
a control unit (<NUM>) configured to control operation of the gripping unit (<NUM>), wherein when a prescribed condition is fulfilled by at least one of an operating distance of the gripping unit (<NUM>) and a weighing result from the weighing unit (<NUM>), the control unit (<NUM>) configured to control operation of the gripping unit (<NUM>) so as to return the articles gripped by the gripping unit (<NUM>) to the container (<NUM>).