Workpiece gripping apparatus and workpiece gripping method

Abstract

In the present invention, a workpiece gripping apparatus comprises a gripper, a rotation unit, a drive device, and a controller. The gripper grips a workpiece transported by a transport unit. The rotation unit rotates the gripper so as to adjust the angle of the gripper with respect to a horizontal plane. The drive device includes a traverse unit and a lifting unit for moving the gripper and the rotation unit longitudinally and vertically. The controller controls the drive device and the rotation unit so that the workpiece is gripped by the gripper at a gripping position on the transport unit.

Description

Workpiece gripping device and workpiece gripping method

[0001] The present disclosure relates to a workpiece gripping device and a workpiece gripping method.

[0002] There are known meat processing machines that automatically transport and process meat as workpieces. For example, Patent Document 1 discloses a meat processing machine that includes multiple conveyors for transporting workpieces. In this document, the workpieces transported by the conveyors are fed into a creasing station.

[0003] WO 2009 / 139031

[0004] In a processing station provided in a meat processing machine such as that described in Patent Document 1, workpieces transported by a conveyor are processed while lying on the conveyor. The processing station uses the same hardware and software to enable multiple processing of various types and shapes. Because the robot arm used in multiple processing in this type of processing station requires relatively little force, it is difficult to perform processing requiring a large force, such as peeling meat from a workpiece. Therefore, in order to peel meat from a workpiece in a conventional processing station, it is necessary to gradually cut the meat with a blade, which increases processing time and reduces yield because the knife-like blade must be inserted in a straight line into the round bone.

[0005] To improve the efficiency of meat processing, for example, a robot arm could automatically grasp a workpiece transported on a conveyor, perform the necessary processing while suspended by the robot arm, and then peel the meat. However, because the shapes of the workpieces to be processed vary considerably depending on individual differences and the quality of pre-processing, it is not easy for a robot arm to properly grasp a workpiece transported on a conveyor. Furthermore, while a robot arm can perform various processing operations depending on the software installed in the controller, as mentioned above, it is disadvantageous for operations requiring a large force, such as peeling meat. If a robot arm needs to handle a large force, the robot arm would need to be large, and the equipment would need to be large.

[0006] At least one embodiment of the present disclosure has been made in consideration of the above-mentioned circumstances, and aims to provide a workpiece gripping device and a workpiece gripping method that have a simple configuration, can accurately grip a workpiece on a transport unit, and can operate the gripped workpiece with a large driving force.

[0007] (1) In order to solve the above-mentioned problems, a workpiece gripping device according to at least one aspect of the present disclosure includes: a gripper for gripping a workpiece transported by a transport unit; a rotation unit for rotating the gripper to adjust the angle of the gripper relative to a horizontal plane; a drive device including a traverse unit and a lifting unit for moving the gripper and the rotation unit back and forth and up and down; and a controller for controlling the drive device and the rotation unit so that the workpiece is gripped by the gripper at a gripping position on the transport unit.

[0008] According to the above aspect (1), by controlling the drive device and the rotation unit, the angle of the gripper relative to the horizontal plane and the front-to-back and up-to-down positions of the gripper can be adjusted, thereby enabling the workpiece on the transport unit to be gripped appropriately. This allows the workpiece on the transport unit to be gripped appropriately with a simple configuration that does not use a weak robot arm.

[0009] (2) In another aspect, in the aspect (1) above, a first sensor is further provided for detecting that the tip of the workpiece on the transport unit has reached a first position, and when the first sensor detects that the tip of the workpiece has reached the first position, the controller moves the gripping portion of the workpiece to the gripping position by moving the transport unit back in the opposite direction by a predetermined amount.

[0010] According to the above aspect (2), the first sensor detects that the leading end of the workpiece being transported has reached the first position. In this case, the transport unit is returned in the reverse direction by a predetermined distance, thereby accurately moving the gripping portion of the workpiece to the gripping position on the transport unit. As a result, by controlling the drive device and the rotating unit as described above, the gripper can approach the gripping position on the transport unit, thereby making it possible to appropriately grip the workpiece on the transport unit.

[0011] (3) In another aspect, in the aspect (1) or (2) above, a guide is provided for adjusting the posture of the workpiece transported by the transport unit.

[0012] According to the above aspect (3), the guide is provided on the transport unit, so that the posture of the workpiece being transported by the transport unit is adjusted. This makes the posture of the workpiece on the transport unit uniform, and enables the workpiece to be gripped with precision by the gripper moved by the drive device and the rotating unit.

[0013] (4) In another aspect, in the aspect (3) above, the guide includes a pair of guide members arranged on both sides of the width direction of the transport unit so that the distance between them decreases toward the downstream side of the transport unit.

[0014] According to the above aspect (4), a pair of guide members are provided on both sides of the transport unit in the width direction. The pair of guide members are arranged so that the distance between them decreases toward the downstream side, thereby making it possible to suitably adjust the posture of the workpiece transported by the transport unit so that the central axis of the workpiece is centered between the pair of guide members.

[0015] (5) In another aspect, in the aspect (1) above, the system further includes a first sensor for detecting that the tip of the work on the transport unit has reached a first position that is a first distance from the downstream end of the transport unit; a second sensor for detecting that the tip of the work on the transport unit has reached a second position that is a second distance from the downstream end of the transport unit that is closer than the first distance; a guide for adjusting the posture of the work transported by the transport unit; and a holding pressure adjustment unit for adjusting the holding pressure of the guide, wherein when the second sensor detects that the tip of the work transported in the forward direction by the transport unit has reached the second position, the controller adjusts the holding pressure of the guide to decrease it using the holding pressure adjustment unit, and then moves the gripping portion of the work to the gripping position by further transporting the work in the forward direction by the transport unit so that the tip of the work reaches the first position.

[0016] According to the above aspect (5), when the second sensor detects that the tip of the workpiece being transported in the forward direction has reached the second position, the holding pressure of the guide, which adjusts the posture of the workpiece being transported, is adjusted to decrease. The pressing load that the workpiece receives from the guide when it contacts the guide during transport can vary depending on the hardness of the workpiece. However, by adjusting the holding pressure of the guide to decrease in this manner, the pressing load that the workpiece receives from the guide can be alleviated, and transport problems such as the workpiece climbing up onto the guide during transport can be effectively prevented. This allows the guide to absorb the pressing load that the workpiece receives when it contacts the guide during transport, thereby enabling accurate transport to the gripping position. As a result, the combination of the rotation of the gripper by the rotating unit and the movement in the forward, backward, and up-down directions by the traversing unit and the lifting unit as described above allows the workpiece moved to the gripping position to be gripped accurately.

[0017] (6) In another aspect, in the aspect (5) above, when the first sensor detects that the tip of the workpiece being transported in the forward direction by the transport unit has reached the first position, the controller readjusts the holding pressure of the guide using the holding pressure adjustment unit.

[0018] According to the above aspect (6), when the leading end of the workpiece being transported by the transport unit reaches the first position, the holding pressure of the guide is readjusted. This readjustment of the holding pressure is performed so that the workpiece is again in the appropriate gripping position, allowing the gripper to grip the workpiece with high precision.

[0019] (7) In another aspect, in the aspect (5) or (6) above, the controller controls the transport unit so that the workpiece is transported in a forward direction against the holding pressure of the guide until the tip of the workpiece reaches the first position from the second position.

[0020] According to the above aspect (7), the workpiece being transported in the forward direction by the transport unit is supported by the guide adjusted to reduce the holding pressure while the tip of the workpiece reaches the first position from the second position, thereby effectively preventing transport problems such as the workpiece climbing up onto the guide due to an excessive pressing load applied to the workpiece from the guide.

[0021] (8) In another aspect, in any one of the above aspects (5) to (7), the holding pressure adjusting unit adjusts the holding pressure based on the temperature of the workpiece.

[0022] According to the above aspect (8), when the hardness of the workpiece depends on the temperature of the workpiece, by adjusting the holding pressure of the guide as described above, it is possible to effectively prevent transport problems such as the workpiece being transported climbing up onto the guide.

[0023] (9) In another aspect, in any one of the aspects (5) to (8) above, the guide includes a pair of guide members arranged on both sides of the width of the conveying unit so that the distance between them decreases toward the downstream side of the conveying unit.

[0024] According to the above aspect (9), a pair of guide members are provided on both sides of the transport unit in the width direction. The pair of guide members are arranged so that the distance between them decreases toward the downstream side, thereby making it possible to suitably adjust the posture of the workpiece transported by the transport unit so that the central axis of the workpiece is centered between the pair of guide members.

[0025] (10) In another aspect, in any one of the aspects (1) to (9) above, a third sensor is further provided for detecting the portion of the workpiece gripped by the gripper when the workpiece gripped by the gripper is rotated into a hanging position by the rotation unit.

[0026] According to the above aspect (10), the workpiece held on the transport unit is placed in a hanging position by the rotation of the gripper by the rotating unit. The third sensor detects the gripped portion of the workpiece in the hanging position, and the positions where various processes are performed can be suitably identified based on the gripped portion.

[0027] (11) In another aspect, in the aspect (10) above, the processing position of the workpiece is determined by comparing the gripped portion detected by the third sensor with image data of the workpiece.

[0028] According to the above aspect (11), by comparing the gripping position of the workpiece by the gripper detected by the third sensor with image data of the workpiece acquired in advance, it is possible to suitably determine the processing position, which is the position where various processes are performed on the workpiece.

[0029] (12) In another aspect, in the aspect (11), the processing position is a notch for inserting a meat separator extending horizontally.

[0030] According to the above aspect (12), the cutout portion for inserting the meat separator used to peel the meat from the workpiece can be suitably determined based on the gripping position detected by the third sensor, and the meat peeling process can be suitably performed by inserting the meat separator into the cutout portion.

[0031] (13) In another aspect, in the aspect (12) above, the controller controls the drive device to raise and lower the gripper holding the workpiece while the meat separator is inserted into the cutout portion.

[0032] According to the above aspect (13), by raising and lowering the gripper while gripping the workpiece, a large peeling force can be applied to the meat separator inserted into the notch, thereby enabling the meat peeling process to be performed with a simple configuration and using a larger force than with a robot arm.

[0033] (14) In another aspect, in any one of the aspects (1) to (13) above, the rotation unit has: a first rotation mechanism for rotating the gripper around a first axis along the vertical plane; and a second rotation mechanism for rotating the gripper around a second axis intersecting the first axis.

[0034] According to the above aspect (14), by rotating the gripper around the first axis and the second axis, the degree of freedom of the gripper is improved, and the workpiece on the transport unit can be more flexibly gripped.

[0035] (15) In order to solve the above-mentioned problems, at least one aspect of the present disclosure provides a workpiece gripping method comprising: a gripper for gripping a workpiece transported by a transport unit; a rotation unit for rotating the gripper to adjust the angle of the gripper relative to a horizontal plane; and a drive device including a traverse unit and a lifting unit for moving the gripper and the rotation unit back and forth and up and down, wherein the drive device and the rotation unit are controlled so that the workpiece is gripped by the gripper at a gripping position on the transport unit.

[0036] According to the above aspect (15), by controlling the drive device and the rotation unit, the angle of the gripper relative to the horizontal plane and the front-to-back and up-to-down positions of the gripper can be adjusted, thereby enabling the workpiece at the gripping position on the transport unit to be gripped appropriately. This allows the workpiece on the transport unit to be gripped appropriately with a simple configuration that does not use a weak robot arm.

[0037] According to at least one embodiment of the present disclosure, a workpiece gripping device and a workpiece gripping method can be provided that have a simple configuration, can accurately grip a workpiece on a transport unit, and can operate the gripped workpiece with a large driving force.

[0038] 7 is a schematic diagram of a meat processing system according to one embodiment; FIG. 1 is a schematic diagram of the workpiece of FIG. 1; FIG. 1 is a schematic diagram of the meat processing apparatus of FIG. 1 from the side; FIG. 3 is an enlarged view of the periphery of the gripper of FIG. 3; FIG. 4 is an enlarged view of the vicinity of the downstream end of the conveyor of FIG. 3 from above; FIG. 4 is a schematic perspective view of the processing apparatus of FIG. 3; FIG. 5 is a flowchart showing a meat processing method according to one embodiment; FIG. 6 is an explanatory diagram corresponding to step S101 of FIG. 7; FIG. 7 is an explanatory diagram corresponding to step S103 of FIG. 7; FIG. 8 is an explanatory diagram corresponding to step S104 of FIG. 7; FIG. 9 is an explanatory diagram corresponding to step S105 of FIG. 7; FIG. 10 is an explanatory diagram corresponding to step S107 of FIG. 7; FIG. 11 is a modification of FIG. 5; FIG. 12 is a flowchart showing a meat processing method that can be performed by a processing apparatus equipped with a workpiece gripping device according to the modification of FIG. 9; FIG. 13 is an explanatory diagram corresponding to steps S200 to S204 of FIG. 10; FIG. 14 is an explanatory diagram corresponding to steps S200 to S204 of FIG. 10.

[0039] Hereinafter, several embodiments of the present invention will be described with reference to the accompanying drawings. However, the dimensions, materials, shapes, relative arrangements, etc. of the components described as embodiments or shown in the drawings are merely illustrative examples and are not intended to limit the scope of the present invention.

[0040] Fig. 1 is a schematic diagram of a meat processing system 1 according to one embodiment, and Fig. 2 is a schematic diagram of a work 2 shown in Fig. 1. The meat processing system 1 is a system for automatically transporting and processing the work 2, which is meat.

[0041] As shown in Figure 2, the work 2 is meat including a bone portion 2a and a meat portion 2b. In this embodiment, a bird leg having an ankle portion 2c is shown as an example of the work 2. In this work 2, the meat portion 2b is mostly attached to the side opposite the ankle portion 2c. The ankle portion 2c has less meat portion 2b attached thereto and is relatively narrow. Note that the work 2 shown in Figure 3 is merely an example, and may be meat from pork, beef, fish, horse, or the like, and the part of the meat is not limited.

[0042] As shown in FIG. 1, the meat processing system 1 comprises a conveying unit 3 , at least one processing station 7 , and at least one meat processing device 10 .

[0043] The transport unit 3 is configured to transport the workpieces 2 to be processed, and has a conveyor 4 that can transport the workpieces 2 supplied from a supply unit (not shown) located upstream to a processing station 7 or meat processing device 10 located downstream. The conveyor 4 receives the workpieces 2 from the supply unit at an entrance 5 located at the most upstream side. Near the entrance 5, pre-processing areas 6 where workers can be positioned are provided on both sides of the conveyor 4. In the pre-processing areas 6, the workpieces 2 can be appropriately pre-processed before being processed in the processing station 7 or meat processing device 10 located downstream.

[0044] The conveyor 4 is configured as a single lane relatively upstream of the transport unit 3, including the pre-processing area 6, but partway through and relatively downstream, it branches into a left lane 4L and a right lane 4R, and a switching unit (not shown) distributes the work 2 transported from the upstream side to either the left lane 4L or the right lane 4R. The left lane 4L or the right lane 4R is provided with a corresponding processing station 7 and meat processing device 10, respectively. The work 2 processed in the processing station 7 and meat processing device 10 are transported to the outside via an output lane. In the following description, when the left lane 4L and the right lane 4R are not to be distinguished, they will be collectively referred to as the conveyor 4.

[0045] The processing station 7 receives the workpieces 2 from the conveyor 4 and processes the meat using a multi-axis robot (not shown) equipped with a meat processing tool. The meat processing performed in the processing station 7 is performed using a relatively small force, as in conventional meat processing devices for performing meat processing such as scoring on workpieces (see, for example, Japanese Patent Nos. 4961613, 4867050, 5788076, 5788077, or JP 2022-170894A).

[0046] In this embodiment, two processing stations 7 are provided along each of the left lane 4L and the right lane 4R, but the number of processing stations 7 provided in each lane is not limited. The processing stations 7 may have the same configuration as each other, or may have different configurations.

[0047] The meat processing device 10 is a device that is transported by the transport unit 3, grips the workpiece 2 on the conveyor 4, and performs processing on the gripped workpiece 2. The meat processing device 10 is equipped with a workpiece gripping device 20 and a processing processing device 50, which will be described later. The workpiece gripping device 20 is a device that is transported by the transport unit 3 and grips the workpiece 2 on the conveyor 4, and the processing processing device 50 is a device that cooperates with the workpiece gripping device 20 to perform various processes on the workpiece 2 gripped by the workpiece gripping device 20.

[0048] The processing performed by the meat processing apparatus 10 includes processing that requires a greater force than that performed by the processing station 7. In this embodiment, the process of peeling meat portions 2b from the workpieces 2 will be described as an example of the processing performed by the meat processing apparatus 10, but other processes may also be performed. The meat portions 2b separated by peeling from the workpieces 2 are carried out to the outside by an output conveyor (not shown) located at the lower level (the remaining workpieces 2 from which the meat portions 2b have been separated are returned to the conveyor 4 and transported to another process downstream).

[0049] The meat processing system 1 also includes a controller (not shown) for controlling the above components. The controller is one or more arithmetic units. The processor included in the arithmetic unit may be a CPU, GPU, MPU, DSP, or a combination thereof, or may be realized by an integrated circuit such as a PLD, ASIC, FPGA, or MCU. The arithmetic unit may include memory such as ROM, RAM, or flash memory, as appropriate.

[0050] Next, a specific description will be given of the configuration of the workpiece gripping device 20 provided in the meat processing apparatus 10. Figure 3 is a schematic diagram showing the meat processing apparatus 10 of Figure 1 from the side, Figure 4 is an enlarged view of the periphery of the gripper 22 of Figure 3, Figure 5 is an enlarged view of the vicinity of the downstream end of the conveyor 4 of Figure 3 from above, and Figure 6 is a perspective view showing a schematic view of the processing device 50 of Figure 3.

[0051] The workpiece gripping device 20 includes a gripper 22, a rotating unit 24, and a drive device 30. The gripper 22, the rotating unit 24, and the drive device 30 are all automatically controlled based on control signals from a controller, and can cooperate with each other to perform the functions described below.

[0052] As shown in Fig. 4, the gripper 22 has a pair of claws 22a, 22b that can be opened and closed in response to a control signal from a controller. When the gripper 22 is in an open state, a gap larger than the ankle portion 2c, which is a gripping portion of the workpiece 2, is provided between the pair of claws 22a, 22b, allowing the ankle portion 2c of the workpiece 2 to be inserted into the gap. On the other hand, when the gripper 22 is in a closed state, the inner sides of the pair of claws 22a, 22b contract so as to come into contact with the ankle portion 2c, thereby allowing the ankle portion 2c of the workpiece 2 inserted into the gap to be gripped by the gripper 22 (note that Fig. 4 illustrates a case where the gripper 22 is in a closed state).

[0053] In the opening and closing operation of the gripper 22, both of the pair of claws 22a, 22b may be movable, or one may be fixed and only the other may be movable.

[0054] The rotation unit 24 is configured to rotate the gripper 22. The rotation unit 24 is capable of adjusting at least the angle of the gripper 22 with respect to a horizontal plane. As shown in Fig. 4, the rotation unit 24 has a first rotation mechanism 24a and a second rotation mechanism 24b having different rotation axes (i.e., the gripper is capable of rotating around two axes). In this embodiment, in particular, the rotation axes of the first rotation mechanism 24a and the second rotation mechanism 24b are configured to be perpendicular to each other.

[0055] The first rotation mechanism 24a is configured to rotate the gripper 22 about a first rotation axis a to adjust the angle of the gripper 22 with respect to the horizontal plane. The first rotation mechanism 24a includes an actuator 26 as a power source for rotating the gripper 22 about the first axis a. A hydraulic cylinder, a pneumatic cylinder, or an electric cylinder can be used as the actuator. The actuator 26 is adjusted based on a control signal from the controller described above, thereby enabling control of the amount of rotation of the gripper 22 about the first rotation axis a.

[0056] The second rotation mechanism 24b is configured to rotate the gripper 22 about a second rotation axis b that intersects with the first rotation axis a. The second rotation mechanism 24b includes an actuator 28 as a power source for rotating the gripper 22 about the second rotation axis b. A hydraulic cylinder, a pneumatic cylinder, or an electric cylinder can be used as the actuator. The actuator 28 is adjusted based on a control signal from the controller described above, thereby controlling the amount of rotation of the gripper 22 about the second rotation axis b.

[0057] The drive device 30 is a device for moving the rotation unit 24 on which the gripper 22 is mounted, back and forth and up and down. As shown in FIG. 3 , the drive device 30 includes, as a traverse unit and an elevation unit, a first rail 32 extending along a first direction X and a second rail 34 extending along a second direction Y intersecting the first direction X. In this embodiment, the first direction X and the second direction Y intersect perpendicularly with each other. The gripper 22 is movable on the first rail 32 and the second rail 34 together with the rotation unit 24. That is, the gripper 22 is movable on the first rail 32 along the first direction X and on the second rail 34 along the second direction Y.

[0058] Furthermore, in the drive device 30, the first rail 32 extending along the first direction X can be moved along the second direction Y by power from a servo motor, which is a drive source (not shown). The second rail 34 extending along the second direction Y can be moved along the first direction X by power from a servo motor, which is a drive source (not shown). These servo motors are driven based on control signals from the controller described above, and can move the position of the gripper 22 mounted on the first rail 32 and the second rail 34 to any position on the XY plane via the rotation unit.

[0059] In this way, in the workpiece gripping device 20, by combining the operation of the rotating unit 24 and the operation of the drive device 30, the gripper 22 can be operated with a high degree of freedom on a two-dimensional plane (a plane parallel to the paper surface) defined by the first direction X and the second direction Y. This allows the gripper 22 to approach the ankle portion 2c of the workpiece 2 at the gripping position on the conveyor 4 at an appropriate angle, and the gripping operation by the gripper 22 can be achieved with high precision using a simple configuration. Specific control methods for the rotating unit 24 and the drive device 30 will be described later.

[0060] As shown in FIG. 5 , a guide 38 is provided on the conveyor 4 to adjust the posture of the workpiece 2 being transported from the upstream side. The workpiece 2 is loaded onto the conveyor 4 from the upstream side in a posture in which the leading end 2d faces substantially downstream, but there is considerable variation in this posture. The guide 38 includes a pair of guide members 38a, 38b arranged on both sides of the width direction of the conveyor 4 so that the distance between them decreases toward the downstream side of the conveyor 4. The posture of the workpiece 2 being transported in the forward direction on the conveyor 4 is adjusted by the pair of guide members 38a, 38b so that the leading end 2d is centered, thereby making the posture of the workpiece 2 on the conveyor 4 uniform. This allows the gripper 22 to grip the workpiece 2 on the conveyor 4 with high precision.

[0061] The pair of guide members 38a, 38b are installed at a predetermined angle with respect to the extending direction of the conveyor 4, and may be configured so that the angle is variable as required.

[0062] A first sensor 40 is also disposed near the downstream end of the conveyor 4. The first sensor 40 is an optical sensor that emits measurement light and detects the reflected light, thereby enabling non-contact detection that the leading end 2d of the workpiece 2 being transported on the conveyor 4 has reached the first position P1. As described above, in the case where a guide 38 is provided on the conveyor 4, the first sensor 40 can detect that the leading end 2d of the workpiece 2 has reached the first position P1 after its posture has been adjusted by the guide 38.

[0063] The first position P1 is located at a position separated by a first distance X1 from the downstream end of the conveyor 4. The first sensor 40 is provided at a position corresponding to the first position P1, from the side of the conveyor 4, where the first sensor 40 can emit measurement light in a direction approximately perpendicular to the extension direction of the conveyor 4. When the first sensor 40 detects that the tip 2d of the workpiece 2 has reached the first position P1, as will be described later with reference to FIG. 8A , the controller returns the conveyor 4 in the reverse direction by a predetermined amount, thereby accurately moving the gripping portion of the workpiece (near the ankle 2c) to the gripping position on the conveyor 4. As a result, the workpiece 2 moved to the gripping position can be accurately gripped by a combination of the rotational movement of the gripper 22 by the rotating unit 24 as described above and the movement in the front-to-back and up-and-down directions by the traversing unit and the lifting unit that constitute the drive device 30.

[0064] The processing device 50 is a device for performing a predetermined processing operation on the workpiece 2 gripped by the gripper 22 while the workpiece 2 is suspended at a predetermined position by the above-mentioned rotating unit 24 and drive device 30.

[0065] The processing device 50 includes a third sensor 42 for detecting the state of the workpiece 2 in the hanging position. In this embodiment, the third sensor 42 is a non-contact optical sensor, similar to the above-described first sensor 40, and is configured to detect the portion of the workpiece 2 gripped by the gripper 22 in the hanging position.

[0066] The detection result of the third sensor 42 is transmitted to the controller and used to determine the position where processing should be performed by the processing device 50. That is, by detecting the portion of the workpiece 2 held by the gripper 22 in the hanging position by the third sensor 42, the position where various processes should be performed by the processing device 50 can be suitably identified based on the held portion.

[0067] At this time, if the controller has information about the shape of the workpiece 2 on the conveyor 4 before it is gripped by the workpiece gripping device 20, the controller may make the above determination by taking into account this information in addition to the detection result of the third sensor 42. For example, if image data of the workpiece 2 has been acquired by an imaging device (not shown) upstream of the gripping position on the conveyor 4, the controller may determine the processing position of the workpiece 2 by comparing the gripping portion by the gripper 22 detected by the third sensor 42 with the image data.

[0068] The processing device 30 includes a robot arm 45 (see FIG. 6 ) having at its tip a tool 43 capable of forming a notch (not shown) in the workpiece 2, and a meat separator 46 that can be inserted into the notch formed in the workpiece 2. The robot arm 45 is a multi-axis robot that is movable based on control signals from a controller (not shown). The robot arm 45 has a robot structure with six or more axes, and the tool 43 mounted at its tip can approach the workpiece 2 at any angle or posture. The controller controls the robot arm 45, for example, to form a notch at a processing position identified by the detection result of the third sensor 42 as described above.

[0069] The meat separator 46 has a plate-like portion extending horizontally. A support portion 44 is disposed on the opposite side of the workpiece 2 gripped by the gripper 22 from the meat separator 46. The workpiece 2 is sandwiched between the meat separator 46 inserted into the notch and the support portion 44. The support portion 44 can be rotated by an actuator (not shown). In this state, as will be described later with reference to FIG. 8E , the gripper 22 is moved upward, whereby the meat portion 2b sandwiched between the meat separator 46 and the support portion 44 is peeled off from the workpiece 2.

[0070] The support portion 44 is provided with a recess 47 corresponding to the workpiece 2. This prevents the workpiece 2 from shifting laterally when the workpiece 2 is clamped between the meat separator 46 and the support portion 44, and stabilizes the posture of the workpiece 2.

[0071] Next, a description will be given of a meat processing method carried out by the meat processing system 10 having the above configuration. Figure 7 is a flowchart showing a meat processing method according to one embodiment, and Figures 8A to 8E are explanatory diagrams corresponding to the steps in Figure 7.

[0072] First, while the workpieces 2 are being transported sequentially on the conveyor 4, the first sensor 40 determines whether the tip 2d of a specific workpiece 2 has reached the first position P1 (step S100). When the first sensor 40 detects that the tip 2d of the workpiece 2 has reached the first position P1 (step S100: YES), the conveyor 4 is returned in the opposite direction by a predetermined amount ΔX (step S101), as shown in FIG. 8A, so that the gripping portion of the workpiece 2 is adjusted to the gripping position of the conveyor 4.

[0073] The ankle portion 2c of the workpiece 2 may vary in size depending on pre-processing, and is a portion with large individual differences. However, by moving the conveyor 4 back in the opposite direction by a predetermined amount ΔX after the tip portion 2d of the workpiece 2 reaches the first position P1 using the first sensor 40, the position that is back by the predetermined amount ΔX from the tip portion 2d of the workpiece 2 can be uniformly identified as the gripping position, regardless of the size of the ankle portion 2c of the workpiece 2.

[0074] Next, the controller controls the turning unit 24 and the driving device 30 to move the gripper 22 to a gripping position on the conveyor 4 (step S102). In step S102, as described above, the turning unit 24 adjusts the angle of the gripper 22 to an appropriate angle for gripping the workpiece 2, and the driving device 30 controls the gripper 22 to approach the gripping position on the conveyor 4.

[0075] 8B, the controller controls the gripper 22 to grip the gripped portion of the workpiece 2 at the gripping position (step S103). In step S103, the gripped portion of the workpiece 2 is inserted between the pair of claws 22a, 22b of the gripper 22 in the open state, and the gripper 22 is closed to reduce the gap between the pair of claws 22a, 22b, thereby gripping the workpiece 2.

[0076] 8C, the controller controls the turning unit 24 and the driving device 30 to move the workpiece 2 by the gripper 22 so that the workpiece 2 assumes a hanging posture (step S104). In step S104, the turning unit 24 and the driving device 30 cooperate to lift the gripped workpiece 2 from the conveyor 4. Then, at a predetermined position where the workpiece 2 does not interfere with the conveyor 4, the turning unit 24 causes the angle of the gripper 22 to become substantially horizontal, thereby realizing a hanging posture in which the flesh of the workpiece 2 is downward.

[0077] 8D, the gripped portion of the workpiece 2 in the hanging position is detected by the third sensor 42 (see FIG. 6) (step S105), and the processing position where the processing is performed is identified based on the detection result (step S106). In step S106, as described above, if image data of the workpiece 2 has been acquired in advance, the detection result of the third sensor 42 may be compared with the image data to identify the processing position.

[0078] Next, processing is performed at the processing position identified in step S106 (step S107). In this embodiment, as an example of processing, as shown in FIG. 8E, a meat separator included in the processing device 30 is inserted into a cutout formed at the processing position, and the meat portion is separated from the workpiece 2 by raising and lowering the gripper 22 gripping the workpiece 2 while the meat separator is fixed between the workpiece 2 and the support. By raising and lowering the gripper 22 while gripping the workpiece 2 in this manner, a large peeling force can be applied between the gripper 22 and the meat separator inserted into the cutout. This allows the meat peeling process to be performed with a simple configuration and using a larger force than a robot arm.

[0079] 9 is a modified example of FIG. 5. The workpiece gripping device 20 according to this modified example includes a second sensor 41 in addition to the first sensor 40 described above. The second sensor 41 is configured to detect the arrival of the workpiece 2 at a second position P2, which is a second distance X2 from the downstream end of the conveyor 4 constituting the transport unit 3. The second distance X2 is shorter than the first distance X1 corresponding to the first sensor 40 (i.e., the second sensor 41 is installed at a position closer to the downstream end of the conveyor 4 than the first sensor 40). Like the first sensor 40 described above, the second sensor 41 is an optical sensor that emits measurement light and detects the reflected light, thereby enabling non-contact detection that the leading end 2d of the workpiece 2 transported on the conveyor 4 has reached the second position P2.

[0080] The workpiece gripping device 20 of this modified example also includes a holding pressure adjustment unit 52 for adjusting the holding pressure of the aforementioned guide 38. The guide members 38a, 38b that make up the guide 38 are held against the edge of the conveyor 4 that makes up the transport unit 3 by a predetermined holding mechanism. The holding pressure of the guide members 38a, 38b by the holding mechanism can be adjusted as appropriate by the holding pressure adjustment unit 52. The adjustment of the holding pressure by the holding pressure adjustment unit 52 may be performed manually by an operator, or may be performed automatically by a controller (not shown).

[0081] FIG. 10 is a flowchart showing a meat processing method that can be carried out by a processing device 50 equipped with a workpiece gripping device 20 according to the modified example of FIG. 9, and FIGS. 11A to 11C are explanatory diagrams corresponding to the steps of FIG. 10.

[0082] First, while the workpieces 2 are being transported in the forward direction on the conveyor 4 (step S200), the second sensor 41 determines whether the tip 2d of the specific workpiece 2 has reached the second position P2 (step S201). As shown in Fig. 11A, when the second sensor 41 detects that the tip 2d of the workpiece 2 has reached the second position P2 (step S201: YES), the holding pressure adjustment unit 52 adjusts the holding pressure of the guide 38 to decrease it (step S202).

[0083] After the holding pressure of the guide 38 is adjusted to decrease in this manner, as shown in FIG. 11B , the workpiece 2 is further conveyed downstream on the conveyor 4, with its side surface coming into contact with the guide 38, and is subjected to a pressing load from the guide 38. At this time, the workpiece 2 is subjected to the pressing load by a pair of guide members 38a and 38b arranged on both sides of the conveyor 4, and its posture is adjusted so that the tip 2d of the workpiece 2 is positioned on the center line of the conveyor 4. The pressing load applied by the guide 38 at this time depends on the hardness of the workpiece 2. If the pressing load is excessive, there is a risk of poor conveyance, such as the workpiece 2 climbing up onto the guide 38. For example, if the workpiece 2 is extremely chilled meat, it is harder than moderately chilled meat, and therefore the workpiece 2 is less likely to deform under the pressing load applied by the guide 38 and is more likely to climb up onto the guide 38. However, in this modified example, the holding pressure is reduced in step S202, and the pressing load that the workpiece 2 receives from the guide 38 is adjusted so that it does not become excessive, and the flexibility of the guide 38 absorbs the pressing load, thereby effectively preventing such transport problems.

[0084] Next, the first sensor 40 determines whether the tip 2d of the workpiece 2, which is further conveyed in the forward direction by the conveyor 4, has reached the first position P1 (step S203). As shown in FIG. 11C , when the first sensor 40 detects that the tip 2d of the workpiece 2 has reached the first position P1 (step S203: YES), the holding pressure adjustment unit 52 readjusts the holding pressure of the guide 38 so that the workpiece is again in the appropriate gripping position (step S204). This enables the gripper to grip the workpiece with high precision.

[0085] In this way, by the processing up to step S204, the leading end 2d of the workpiece 2 can be suitably positioned at the gripping position near the downstream end of the conveyor 4. As a result, by performing the processing from step S205 onwards, the workpiece 2 moved to the gripping position can be gripped with high precision by a combination of the rotational movement of the gripper 22 by the turning unit 24 as described above and the movement in the front-to-back and up-and-down directions by the traversing unit and the lifting unit that make up the drive device 30. Note that the processing from step S205 onwards in Fig. 10 is the same as that from step S102 onwards in Fig. 7, and therefore a duplicated description will be omitted here.

[0086] The adjustment of the holding pressure of the guide 38 in step S202 or S204 can be made based on the hardness of the workpiece 2. In particular, since the hardness of the workpiece 2 is closely related to the temperature of the workpiece 2 (for example, the lower the temperature of the workpiece 2, the harder the workpiece 2), the adjustment of the holding pressure may be made based on the temperature of the workpiece 2.

[0087] Thus, according to this modification, compared to the embodiment described above, although the second sensor 41 and holding pressure adjustment unit 52 are required, the guide 38 can accurately position the workpiece 2 at the gripping position by the guide 38 through software control using these configurations without having to change the design of the hardware configuration such as the guide 38. As a result, even if the user of this system handles various types of workpieces 2 (hardness and temperature), such software control can accurately position the workpiece 2 at the gripping position depending on the state of the workpiece 2.

[0088] As described above, according to each of the above embodiments, by controlling the rotating unit 24 and the drive device 30, the angle of the gripper 22 relative to the horizontal plane and its front-to-back, up-to-down position can be adjusted, and with a simple configuration, the workpiece 2 can be gripped with high precision and can be gripped suitably for processing that requires a large amount of force.

[0089] REFERENCE SIGNS LIST 1 meat processing system 2 workpiece 2a bone portion 2b meat portion 2c ankle portion 2d tip portion 3 transport unit 4 conveyor 5 inlet portion 6 preparation area 7 processing station 10 meat processing device 20 workpiece gripping device 22 gripper 22a, 22b claw portion 24 rotation unit 24a first rotation mechanism 24b second rotation mechanism 26, 28 actuator 30 drive device 32 first rail 34 second rail 38 guide 38a, 38b guide member 40 first sensor 41 second sensor 42 third sensor 43 tool 44 support portion 45 robot arm 46 meat separator 47 recess 50 processing device 52 holding pressure adjustment portion

Claims

1. A workpiece gripping device comprising: a gripper for gripping a workpiece transported by a transport unit; a rotation unit for rotating the gripper to adjust the angle of the gripper with respect to a horizontal plane; a drive device including a traverse unit and a lifting unit for moving the gripper and the rotation unit back and forth and up and down; and a controller for controlling the drive device and the rotation unit so that the workpiece is gripped by the gripper at a gripping position on the transport unit.

2. A workpiece gripping device as described in claim 1, further comprising a first sensor for detecting that a tip of the workpiece on the transport unit has reached a first position, and when the first sensor detects that the tip of the workpiece has reached the first position, the controller moves the gripping portion of the workpiece to the gripping position by moving the transport unit back in the opposite direction a predetermined amount.

3. A workpiece holding device as described in claim 1 or 2, further comprising a guide for adjusting the posture of the workpiece transported by the transport unit.

4. A workpiece holding device as described in claim 3, wherein the guide includes a pair of guide members arranged on both sides of the width of the transport unit so that the distance between them decreases toward the downstream side of the transport unit.

5. A work gripping device as described in claim 1, further comprising: a first sensor for detecting that a tip end of the work on the transport unit has reached a first position which is a first distance from the downstream end of the transport unit; a second sensor for detecting that the tip end of the work on the transport unit has reached a second position which is a second distance from the downstream end of the transport unit which is closer than the first distance; a guide for adjusting the posture of the work transported by the transport unit; and a holding pressure adjustment unit for adjusting the holding pressure of the guide, wherein when it is detected by the second sensor that the tip end of the work transported in the forward direction by the transport unit has reached the second position, the controller adjusts the holding pressure of the guide to decrease it using the holding pressure adjustment unit, and then moves the gripping portion of the work to the gripping position by further transporting the work in the forward direction by the transport unit so that the tip end of the work reaches the first position.

6. A workpiece gripping device as described in claim 5, wherein the controller readjusts the holding pressure of the guide by the holding pressure adjustment unit when the first sensor detects that the tip of the workpiece being transported in the forward direction by the transport unit has reached the first position.

7. A workpiece gripping device as described in claim 5, wherein the controller controls the transport unit so that the workpiece is transported in a forward direction against the holding pressure of the guide until the tip of the workpiece reaches the first position from the second position.

8. A workpiece gripping device as described in claim 5, wherein the holding pressure adjustment unit adjusts the holding pressure based on the temperature of the workpiece.

9. A workpiece gripping device as described in claim 5, wherein the guide includes a pair of guide members arranged on both sides of the width of the transport unit so that the distance between them decreases toward the downstream side of the transport unit.

10. A workpiece gripping device as described in claim 1 or 2, further comprising a third sensor for detecting the gripped portion of the workpiece by the gripper when the workpiece gripped by the gripper is rotated into a hanging position by the rotating unit.

11. A workpiece gripping device as described in claim 10, which determines the processing position of the workpiece by comparing the gripping portion detected by the third sensor with image data of the workpiece.

12. The workpiece gripping device according to claim 11, wherein the processing position is a notch for inserting a meat separator extending along a horizontal direction.

13. The workpiece gripping device according to claim 12, wherein the controller controls the drive device to raise and lower the gripper gripping the workpiece with the meat separator inserted into the cutout portion.

14. A workpiece gripping device as described in claim 1 or 2, wherein the rotating unit has: a first rotating mechanism for rotating the gripper around a first axis along the vertical plane; and a second rotating mechanism for rotating the gripper around a second axis intersecting the first axis.

15. A workpiece gripping method comprising: a gripper for gripping a workpiece transported by a transport unit; a rotation unit for rotating the gripper to adjust the angle of the gripper relative to a horizontal plane; and a drive device including a traverse unit and a lifting unit for moving the gripper and the rotation unit back and forth and up and down, wherein the drive device and the rotation unit are controlled so that the workpiece is gripped by the gripper at a gripping position on the transport unit.

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