Robot arm control device

Abstract

To provide a robot arm control device capable of simplifying processing related to taking out a workpiece.SOLUTION: A robot arm 20 can grip two workpieces 50. An operation control part 32 forces the robot arm to perform the following: taking out two workpieces 50 from a pallet 40 when the set number of inputs, which is the number of inputs set by an input number setting part 31, is two; executing a first operation control to input the workpieces 50 taken out into a container 60; taking out the two workpieces 50 from the pallet 40 when the set number of inputs is one and when the temporary placement number, which is the number of workpieces 50 temporarily placed on a temporary placement table 80, is zero; temporarily placing one from among the workpieces 50 taken out on the temporary placement table and executing a second operation control to input the one from among the workpieces 50 taken out into the container 60; taking out one workpiece 50 from the temporary placement table 80 when the set number of inputs is n-m and when the temporary placement number is one; and executing a third operation control to input the workpieces 50 taken out into the container 60.SELECTED DRAWING: Figure 1

Description

Technical Field

[0001] The present invention relates to a control device for a robot arm.

Background Art

[0002] As disclosed in Patent Document 1, at production sites, there are apparatuses that perform pick-and-place operations in which a robot arm grips and takes out workpieces stored on a pallet, and loads the taken-out workpieces into a predetermined loading location. In this case, from the viewpoint of shortening the operation time, it is desirable not to perform the operation by taking out one workpiece from the pallet each time, but to perform the operation by taking out a plurality of workpieces from the pallet at once.

[0003] Accordingly, conventionally, a configuration has been considered in which a hand having a plurality of gripping portions capable of gripping workpieces is used as the hand of the robot arm to grip and take out a plurality of workpieces at once. For example, according to the configuration of gripping and taking out two workpieces at once, the operation time can be approximately halved compared to a configuration of gripping and taking out one workpiece each time.

Prior Art Documents

Patent Documents

[0004]

Patent Document 1

Summary of the Invention

Problem to be Solved by the Invention

[0005] When dealing with high-mix, low-volume production, the input quantity—the number of workpieces placed in the input area—will not be constant but will fluctuate. For example, a production system might be designed where a robot arm can pick up two workpieces at once, and the input quantity varies between 0 and 2. In such a system, it is common practice to adjust the retrieve quantity—the number of workpieces picked up from the pallet—to match the input quantity. That is, if the input quantity is 1, the retrieve quantity is also 1; if the input quantity is 2, the retrieve quantity is also 2, and so on.

[0006] As shown in the above configuration, making the number of acquired items variable may complicate the pattern calculation for acquiring workpieces in the control device that controls the robot arm. For example, depending on the workpiece acquisition status, it is possible that even if the input quantity is two, only one workpiece may remain in the pallet, in which case acquisition becomes impossible. In this case, a decision must be made as to whether to discard the entire pallet or replace it with the next pallet, thus complicating the handling of pallets. For these reasons, with conventional technology, when considering the handling of high-mix, low-volume production, it is not only impossible to shorten the working time, but it may even lead to a longer working time.

[0007] To resolve this problem, the following solution can be considered. That is, pallets may be stacked in multiple layers. In such a case, if the number of items to be loaded is two, but only one workpiece remains in a given pallet, it is conceivable to simultaneously retrieve the workpiece contained in another stacked pallet. However, simultaneously retrieving workpieces from pallets at different levels introduces another problem: the handling mechanism becomes more complex, requiring variable stroke extension to accommodate workpieces at different levels. The present invention has been made in view of the above circumstances, and its object is to provide a control device for a robot arm that can simplify the process related to workpiece removal. [Means for solving the problem]

[0008] The robot arm control device described in claim 1 controls a robot arm that performs the task of picking up workpieces stored on a pallet and placing them in a loading location, and comprises a loading number setting unit and an operation control unit. The robot arm is capable of gripping N workpieces, which are an integer of 2 or more. The loading location is capable of loading a maximum of N workpieces. In this case, separate from the loading location, there is a temporary storage location where at least N-1 workpieces can be temporarily placed. The maximum number of workpieces stored on the pallet is an integer multiple of N.

[0009] The input quantity setting unit sets the input quantity, which is the number of workpieces to be placed in the input location, based on an input quantity command provided from an external source. The motion control unit controls the movement of the robot arm to remove the workpieces from the pallet and place the removed workpieces in the input location. The motion control unit executes one of the first motion control, second motion control, or third motion control according to the input quantity set by the input quantity setting unit and the temporary placement quantity, which is the number of workpieces temporarily placed in the temporary placement location. In this case, M is an integer between 1 and N-1.

[0010] Specifically, if the input quantity setting unit sets the input quantity to N, the operation control unit executes a first operation control to take N workpieces from the pallet and put the taken workpieces into the input location. Furthermore, if the input quantity setting unit sets the input quantity to NM and the number of workpieces temporarily placed in the temporary storage location is less than NM, the operation control unit executes a second operation control to take N workpieces from the pallet, temporarily place M of the taken workpieces in the temporary storage location, and put NM of the taken workpieces into the input location.In addition, if the input quantity setting unit sets the input quantity to NM and the number of workpieces temporarily placed is NM or more, the operation control unit executes a third operation control to take NM of the workpieces from the temporary storage location and put the taken workpieces into the input location.

[0011] In this way, regardless of whether the number of input items is N or NM, that is, regardless of the number of input items, the number of workpieces removed from the pallet in one operation will be fixed at N. Thus, with the above configuration and control, since N workpieces are removed from the pallet in one operation, the work time can be shortened compared to removing one workpiece at a time from the pallet. In addition, in this case, since the removal pattern is fixed to remove N workpieces each time, it is possible to simplify the processing related to workpiece removal.

[0012] In the above configuration and control, when the number of inputs is N, that is, when the number of workpieces removed matches the number of inputs, the removed workpieces are placed directly into the input location, similar to the conventional technology. However, in the above configuration and control, when the number of inputs is less than N, that is, when the number of inputs is NM, the number of workpieces removed does not match the number of inputs, so the removed workpieces cannot be placed directly into the input location, similar to the conventional technology. Therefore, in the above configuration and control, when the number of inputs is NM, M of the removed workpieces are temporarily placed in a temporary storage location to adjust the number of inputs to the desired number.

[0013] As described above, the workpieces temporarily placed in the temporary storage area are utilized in the following way. That is, in the above configuration and control, if the number of inputs is NM and the number of workpieces temporarily placed in the temporary storage area is NM or more, then instead of a pallet, NM workpieces are taken out from the temporary storage area and these taken workpieces are placed in the input area.

[0014] Furthermore, in this case, the maximum number of workpieces that can be stored on the pallet is an integer multiple of N, and N workpieces are removed in each operation. Therefore, regardless of the number of workpieces initially loaded, the number of remaining workpieces on the pallet can always be reduced to zero by performing a predetermined number of operations. Thus, with the above configuration and control, the situation in which fewer workpieces than the initial load remain on the pallet never occurs, thus avoiding complexity in pallet processing. In this way, the above configuration and control provides the excellent effect of shortening the work time for the pick-and-place operation—that is, the process of removing workpieces from the pallet and placing them in the loading area—while simplifying the processing related to workpiece removal.

[0015] In the above configuration, the input location is generally set to a predetermined location after considering subsequent processes, and the input area for each workpiece may be partitioned in a grid-like manner. Therefore, when inputting a workpiece to the input location, if the hand is gripping extra workpieces other than the workpiece to be input, these extra workpieces may come into contact with workpieces already placed in the input location or partitions in the input location, which may result in the workpiece being displaced or damaged. Therefore, in the control device for the robot arm described in claim 2, the motion control unit, in the second motion control, temporarily places M of the workpieces in the temporary placement location, and then inputs NM of the workpieces to the input location.

[0016] In this way, when placing workpieces into the input area, the extra M workpieces out of the N workpieces taken from the pallet are already temporarily placed in a temporary storage area, and the hand is holding only the NM workpieces that are to be placed. Therefore, according to the above control, when placing workpieces into the input area, the risk of the extra workpieces coming into contact with workpieces already placed in the input area or partitions in the input area, causing the workpieces to shift position or be damaged, can be reduced.

[0017] Furthermore, the temporary placement area can be arranged more freely than the input area, and the input area for each workpiece can be a relatively large area without partitions. Therefore, with the above control, when temporarily placing M workpieces, although the hand is also holding workpieces other than those being temporarily placed, the possibility of a workpiece coming into contact with already temporarily placed workpieces can be kept sufficiently low by devising the arrangement of the temporary placement area and making the input area for each workpiece sufficiently large relative to the size of the workpiece.

[0018] In the control device for the robot arm described in claim 3, the motion control unit, in the second motion control, loads NM of the workpieces into the loading location, and then temporarily places M of the workpieces in the temporary storage location. In other words, in this case, the operation of loading the workpieces into the loading location is performed before the operation of temporarily placing the workpieces in the temporary storage location. This allows for adjustment of the number of workpieces loaded by temporary placement without prolonging the work time required for taking the workpieces stored on the pallet and loading them into the loading location, in other words, while maintaining good productivity efficiency.

[0019] In the control device for the robot arm described in claim 4, a plurality of temporary storage locations are provided. In this case, each of the plurality of temporary storage locations is located on the path from the pallet to the loading location and is located at a different position from one another. With this configuration, when the second operation control is executed, it becomes possible to use the temporary storage location from among the plurality of temporary storage locations that provides the shortest path from the pallet through the temporary storage location to the loading location, and as a result, the work time, including the temporary storage operation, can be minimized. [Brief explanation of the drawing]

[0020] [Figure 1] A schematic diagram showing the configuration of the production system according to the first embodiment. [Figure 2] This figure shows an example of a specific configuration of the robot arm according to the first embodiment. [Figure 3] This diagram schematically shows the process related to pick-and-place operations performed by the controller according to the first embodiment. [Figure 4] A diagram illustrating an example of specific operation when the first operation control according to the first embodiment is executed. [Figure 5] A diagram illustrating an example of specific operation when the second operation control according to the first embodiment is executed. [Figure 6]Diagram for explaining an example of a specific operation when the third operation control according to the first embodiment is executed [Figure 7] Diagram for explaining an example of a specific operation when the first operation control according to the second embodiment is executed [Figure 8] Diagram for explaining an example of a specific operation when the second operation control according to the second embodiment is executed [Figure 9] Diagram 1 for explaining an example of a specific operation when the third operation control according to the second embodiment is executed [Figure 10] Diagram 2 for explaining an example of a specific operation when the third operation control according to the second embodiment is executed [Figure 11] Diagram schematically showing the content of processing related to pick-and-place operations executed by the controller according to the second embodiment [Figure 12] Diagram for explaining a modified example in which a plurality of temporary placement tables according to the second embodiment are provided [Figure 13] Diagram for explaining a modified example in which the shape of the temporary placement table according to the second embodiment is changed [Figure 14] Diagram for explaining a modified example in which the number of workpieces that can be placed on the temporary placement table according to the second embodiment is changed [Mode for Carrying Out the Invention]

[0021] Hereinafter, a plurality of embodiments will be described with reference to the drawings. Note that substantially the same components in each embodiment are denoted by the same reference numerals, and descriptions thereof are omitted. (First Embodiment) Hereinafter, the first embodiment will be described with reference to Figures 1 to 6.

[0022] As shown in Figure 1, the production system 10 of this embodiment consists of a robot arm 20, a controller 30, and the like. The production system 10 includes a process in which the robot arm 20 picks up the workpieces 50 contained in the pallet 40 and places them in the container 60 in an aligned state, that is, a transfer process from the pallet 40 to the container 60. The container 60 is an example of a place to put the workpieces 50. Note that in Figure 1 and other figures, only some workpieces are labeled with reference numerals, and the reference numerals for other workpieces are omitted.

[0023] As shown in Figure 2, the robot arm 20 is configured as a horizontal articulated robot having, for example, a four-axis arm. A hand 70 is attached to the tip of the robot arm 20. The hand 70 has two gripping parts 71 and 72 that can grasp a workpiece 50. The gripping parts 71 and 72 are equipped with a suction mechanism for adsorbing and holding the workpiece 50. Thus, in this embodiment, the robot arm 20 is capable of grasping two workpieces 50.

[0024] The robot arm 20 performs a pick-and-place operation, taking the workpiece 50 stored on the pallet 40 and placing it into the container 60. Specifically, the robot arm 20 rotates its arm so that its tip is above the pallet 40, then lowers the hand 70 attached to the end of the arm, grasps the workpiece 50 with the hand 70, and lifts it up. The robot arm 20 rotates its arm so that its tip is above the container 60, then lowers the hand 70, releases the workpiece 50 from the hand 70, and places it in a predetermined position within the container 60.

[0025] In this embodiment, the workpiece 50 is, for example, confectionery, and the container 60 is, for example, a confectionery box for assorting multiple types of confectionery. As shown in Figure 1, the container 60 is divided into a grid-like structure, and can hold a maximum of two workpieces 50, which is the same number as the number of workpieces 50 that the hand 70 can grasp. The number of workpieces 50 to be placed in the container 60 is variable, ranging from 0 to 2. In this case, separate from the container 60 which is the place to place the workpieces, there is a temporary storage table 80 on which at least one workpiece 50 can be temporarily placed, which is the number of workpieces 50 that the hand 70 can grasp minus "1". The temporary storage table 80 is an example of a temporary storage location.

[0026] Pallet 40 is a container that forms a rectangular shape in plan view. Pallet 40 contains 16 workpieces 50 arranged in 4 rows and 4 columns. In other words, the maximum number of workpieces 50 that can be stored in pallet 40 is 16, which is an integer multiple of 2, the number of workpieces 50 that the hand 70 can grasp.

[0027] The controller 30 functions as a control device for the robot arm and controls the robot arm 20 by executing a computer program in a control means consisting of a computer (not shown) with a CPU, ROM, and RAM. Specifically, the controller 30 is equipped with a drive unit consisting of an inverter circuit and drives each motor based on the rotational position of the motor detected by encoders provided corresponding to the motors that drive each axis of the robot arm 20, for example, by feedback control. The controller 30 controls the robot arm 20 so that each axis of the robot arm 20 automatically performs predetermined movements by executing a preset operation program.

[0028] The controller 30 includes functional blocks such as an input quantity setting unit 31 and an operation control unit 32. Each of these functional blocks is implemented by the CPU of the controller 30 executing a computer program stored in ROM or the like to perform processing corresponding to the computer program; in other words, it is implemented by software. However, it is also possible to configure the controller 30 so that at least a portion of each functional block is implemented by hardware.

[0029] The input quantity setting unit 31 sets the input quantity, which is the number of workpieces 50 to be placed into the container 60, based on an input quantity command provided from an external source. The user can set the input quantity to any number between 1 and 2 by providing an input quantity command to the controller 30 to specify the desired input quantity. The operation control unit 32 controls the movement of the robot arm 20 to remove the workpieces 50 from the pallet 40 and to place the removed workpieces 50 into the container 60.

[0030] The operation control unit 32 executes one of the first, second, or third operation controls according to the set input number, which is the number of inputs set by the input number setting unit 31, and the temporary placement number, which is the number of workpieces 50 temporarily placed on the temporary placement table 80. That is, if the set input number is 2, the operation control unit 32 executes the first operation control, which involves taking 2 workpieces 50 from the pallet 40 and putting those taken workpieces 50 into the container 60.

[0031] Furthermore, if the set number of items to be loaded is 1 and the number of items to be temporarily placed is less than 1, that is, if the number of items to be temporarily placed is 0, the operation control unit 32 performs a second operation control in which it takes out 2 workpieces 50 from the pallet 40, temporarily places one of the 2 workpieces 50 taken out on the temporary placement stand 80, and puts the other of the 2 workpieces 50 taken out into the container 60.

[0032] Furthermore, if the set number of items to be loaded is 1 and the number of items to be temporarily placed is 1 or more, the operation control unit 32 performs a third operation control to remove one workpiece 50 from the temporary placement table 80 and load the removed workpiece 50 into the container 60. In this case, the operation control unit 32 is configured in the second operation control to temporarily place one workpiece 50 on the temporary placement table 80 before loading the workpiece 50 into the container 60.

[0033] The controller 30 repeatedly executes the processing shown in Figure 3, thereby realizing the first, second, and third operation control described above. First, in step S101, it is determined whether or not there is a workpiece 50 on the pallet 40. If there is no workpiece 50 on the pallet 40, the result in step S101 is "NO", and this process ends. On the other hand, if there is a workpiece 50 on the pallet 40, the result in step S101 is "YES", and the process proceeds to step S102.

[0034] In step S102, it is determined whether the set input quantity is 1 or not. If the set input quantity is 2, the result in step S102 is "NO", and the process proceeds to step S103. In step S103, 2 workpieces 50 are taken from pallet 40. After step S103 is executed, the process proceeds to step S104, where the 2 workpieces 50 taken in step S103 are placed into container 60. These steps S103 and S104 correspond to the first operation control. After step S104 is executed, this process is completed.

[0035] On the other hand, if the set number of items to be placed is 1, the result in step S102 is "YES", and the process proceeds to step S105. In step S105, it is determined whether the number of items to be temporarily placed is 0 or not. If the number of items to be temporarily placed is 1, the result in step S105 is "NO", and the process proceeds to step S106. In step S106, one workpiece 50 is taken from the temporary placement table 80. After step S106 is executed, the process proceeds to step S107, and the one workpiece 50 taken in step S106 is placed into the container 60. Steps S106 and S107 correspond to the third operation control. After step S107 is executed, this process is completed.

[0036] On the other hand, if the number of temporarily placed items is 0, the response in step S105 is "YES", and the process proceeds to step S108. In step S108, two workpieces 50 are taken from the pallet 40. After step S108 is completed, the process proceeds to step S109, where one of the two workpieces 50 taken in step S108 is placed on the temporary placement table 80 for temporary placement. After step S109 is completed, the process proceeds to step S110, where one of the two workpieces 50 taken in step S108 is placed on the container 60. These steps S108 to S110 correspond to the second operation control. After step S110 is completed, this process is finished.

[0037] Next, a specific example of the operation of the pick-and-place operation performed by the robot arm 20 with the above configuration will be described with reference to Figures 4 to 6. Note that in Figures 4 to 6, the robot arm 20 is not shown, and only the hand 70 attached to the end of the arm is shown.

[0038] [1] Operation when the first motion control is executed As shown in Figure 4(a), when the set input quantity is 2, the robot arm 20 uses the hand 70 to pick up 2 workpieces 50 from the pallet 40. Then, as shown in Figure 4(b), the robot arm 20 places the 2 picked-up workpieces 50 into the container 60. [2] Operation when the second operation control is executed

[0039] As shown in Figure 5(a), when the set input quantity is 1 and the number of temporarily placed items is 0, the robot arm 20 uses the hand 70 to pick up 2 workpieces 50 from the pallet 40. Then, as shown in Figure 5(b), the robot arm 20 temporarily places one of the two workpieces 50 that it picked up on the temporary placement table 80. Subsequently, as shown in Figure 5(c), the robot arm 20 places one of the two workpieces 50 that it picked up into the container 60. [3] Operation when the third control is executed

[0040] As shown in Figure 6(a), when the set input quantity is 1 and the temporary placement quantity is 1, the robot arm 20 uses the hand 70 to pick up one workpiece 50 from the temporary placement table 80. Then, as shown in Figure 6(b), the robot arm 20 places the picked-up workpiece 50 into the container 60.

[0041] According to the embodiment described above, the following effects can be obtained. The robot arm 20 is equipped with a hand 70 that can grasp two workpieces 50, and the container 60 is designed to hold a maximum of two workpieces, the same number as the number of workpieces 50 that the hand 70 can grasp. In this case, separate from the container 60, there is a temporary storage table 80 on which at least one workpiece 50 can be temporarily placed, which is the number of workpieces 50 that the hand 70 can grasp minus "1".

[0042] In the above configuration, the operation control unit 32 executes one of the first operation control, second operation control, or third operation control according to the set input number, which is the number of inputs set by the input number setting unit 31, and the temporary placement number, which is the number of workpieces 50 temporarily placed on the temporary placement stand 80. That is, if the set input number is 2, the operation control unit 32 executes the first operation control, which involves taking 2 workpieces 50 from the pallet 40 and putting those taken workpieces 50 into the container 60.

[0043] Furthermore, if the set input quantity is 1 and the number of temporarily placed items is less than 1, the operation control unit 32 performs a second operation control in which it takes out 2 workpieces 50 from the pallet 40, temporarily places one of the taken workpieces 50 on the temporary placement table 80, and puts one of the taken workpieces 50 into the container 60. In addition, if the set input quantity is 1 and the number of temporarily placed items is 1 or more, the operation control unit 32 performs a third operation control in which it takes out 1 workpiece 50 from the temporary placement table 80 and puts the taken workpieces 50 into the container 60.

[0044] In this way, regardless of whether the input quantity is two or one, that is, regardless of the number of input items, the number of workpieces 50 removed from the pallet 40 in one operation will be fixed at two. Thus, with the above configuration and control, since two workpieces are removed from the pallet 40 in one operation, the work time can be reduced to approximately half compared to removing one workpiece at a time from the pallet. Furthermore, in this case, since the removal pattern is fixed to remove two workpieces 50 each time, it is possible to simplify the processing in the controller 30 related to the removal of workpieces 50.

[0045] In the above configuration and control, when the number of inputs is 2, that is, when the number of workpieces 50 removed matches the number of inputs, the removed workpieces 50 are placed directly into the container 60, as in the conventional technology. However, in the above configuration and control, when the number of inputs is less than 2, that is, when the number of inputs is 1, the number of workpieces 50 removed does not match the number of inputs, so the removed workpieces 50 cannot be placed directly into the container 60, as in the conventional technology. Therefore, in the above configuration and control, when the number of inputs is 1, one of the removed workpieces 50 is temporarily placed on the temporary storage table 80 to adjust the number of inputs to the desired number.

[0046] As described above, the workpieces 50 temporarily placed on the temporary storage table 80 are used in the following way. That is, in the above configuration and control, if the number of inputs is 1 and the number of temporary placements, which is the number of workpieces 50 temporarily placed on the temporary storage table 80, is 1 or more, one workpiece 50 is taken out from the temporary storage table 80 instead of the pallet 40, and these taken-out workpieces 50 are put into the container 60.

[0047] Furthermore, in this case, the maximum number of workpieces 50 that can be stored in the pallet 40 is 16, which is an integer multiple of 2, the number of workpieces 50 that the hand 70 can grasp. Also, since 2 workpieces are removed in each operation, regardless of the number of workpieces initially loaded, the number of remaining workpieces 50 in the pallet 40 can always be reduced to zero by performing a predetermined number of operations. Therefore, with the above configuration and control, a situation will never occur where fewer workpieces 50 than the number loaded remain in the pallet 40, thus avoiding complexity in the processing of the pallet 40. Thus, this embodiment provides the excellent effect of shortening the working time for the pick-and-place operation, which involves removing workpieces 50 from the pallet 40 and placing them into the container 60, while simplifying the processing related to the removal of workpieces 50.

[0048] In the above configuration, the container 60 is generally placed in a predetermined location, taking into consideration subsequent processes. In this case, the container 60 is divided into grid-like sections for each workpiece 50 to be loaded. Therefore, when loading a workpiece 50 into the container 60, if the hand 70 is holding any extra workpieces 50 other than the one to be loaded, these extra workpieces 50 may come into contact with workpieces already placed in the container 60, or with the partitions of the container 60. As a result, the workpieces 50 may be displaced or damaged. Therefore, in this case, the operation control unit 32, in the second operation control, temporarily places one workpiece 50 on the temporary placement table 80 before loading one workpiece 50 into the container 60.

[0049] In this way, when loading the workpiece 50 into the container 60, the extra workpiece 50 taken from the pallet 40 is already temporarily placed on the temporary storage stand 80, and the hand 70 is holding only the one workpiece 50 that is to be loaded. Therefore, according to the above control, when loading the workpiece 50 into the container 60, the risk of the extra workpiece 50 coming into contact with workpieces 50 already placed in the container 60, the partitions of the container 60, etc., causing the workpiece 50 to shift position or be damaged can be reduced.

[0050] Furthermore, the temporary placement platform 80 can be arranged more freely than the container 60, and the input area for each workpiece 50 can be made relatively large without partitions. Therefore, with the above control, when one workpiece 50 is temporarily placed, the hand 70 is also holding other workpieces 50 besides the one being temporarily placed. However, by devising the arrangement of the temporary placement platform 80 and making the input area for each workpiece 50 sufficiently large relative to the size of the workpiece 50, the possibility of the workpiece 50 coming into contact with already temporarily placed workpieces 50 can be kept to a minimum.

[0051] (Second Embodiment) The second embodiment will be described below with reference to Figures 7 to 14. The robot arm 20 is not limited to being able to grip two workpieces 50; it is acceptable for it to be able to grip three or more workpieces 50, or any number of N workpieces 50 that is an integer of 2 or more.

[0052] Therefore, in this embodiment, the configuration and control of each part will be described when the number of workpieces 50 that the robot arm 20 can grip is generalized to N. As shown in Figures 7 to 10, the hand 70 attached to the tip of the robot arm 20 is equipped with N gripping parts, each having a similar configuration to the gripping parts 71, 72, etc., that can grip the workpieces 50.

[0053] In this case, the container 60 can hold a maximum of N workpieces 50. The number of workpieces 50 placed in the container 60 is variable, ranging from 0 to N. The temporary storage table 80 can temporarily hold at least N-1 workpieces 50. In this case, the temporary storage table 80 is shaped to accommodate N-1 workpieces 50 in a single row. In this case, the pallet 40 contains workpieces 50 arranged in a matrix, in a number that is an integer multiple of N. In other words, in this case, the maximum number of workpieces 50 that can be stored in the pallet 40 is an integer multiple of N.

[0054] The operation control unit 32 executes a first operation control when the set input quantity is N, which involves taking N workpieces 50 from the pallet 40 and placing those workpieces 50 into the container 60. Furthermore, when the set input quantity is NM and the number of temporary placements is less than NM, the operation control unit 32 executes a second operation control when the set input quantity is NM and the number of temporary placements is less than NM, which involves taking N workpieces 50 from the pallet 40, temporarily placing M of those N workpieces 50 on the temporary placement stand 80, and placing NM of those N workpieces 50 into the container 60. Here, M is an integer between 1 and N-1.

[0055] Furthermore, if the set number of items to be loaded is NM and the number of items to be temporarily placed is NM or more, the operation control unit 32 performs a third operation control to remove NM items of workpieces 50 from the temporary placement table 80 and load the removed NM items of workpieces 50 into the container 60. In this case, the operation control unit 32 is configured in the second operation control to temporarily place M items of workpieces 50 on the temporary placement table 80, and then load NM items of workpieces 50 into the container 60.

[0056] The controller 30 repeatedly executes the processing shown in Figure 11, thereby realizing the first, second, and third operation control described above. First, in step S201, it is determined whether or not there is a workpiece 50 on the pallet 40. If there is no workpiece 50 on the pallet 40, the result in step S201 is "NO", and this process ends. On the other hand, if there is a workpiece 50 on the pallet 40, the result in step S201 is "YES", and the process proceeds to step S202.

[0057] In step S202, it is determined whether the set input quantity is N-1 or less. If the set input quantity is N, the result in step S202 is "NO", and the process proceeds to step S203. In step S203, N workpieces 50 are obtained from pallet 40. After step S203 is executed, the process proceeds to step S204, where the N workpieces 50 obtained in step S203 are placed into container 60. Steps S203 and S204 correspond to the first operation control. After step S204 is executed, this process is completed.

[0058] On the other hand, if the set number of items to be placed is N-1 or less, the result in step S202 is "YES", and the process proceeds to step S205. In step S205, it is determined whether the number of items to be temporarily placed is less than NM. If the number of items to be temporarily placed is NM or greater, the result in step S205 is "NO", and the process proceeds to step S206. In step S206, NM items of workpieces 50 are taken from the temporary placement table 80. After step S206 is completed, the process proceeds to step S207, where the NM items of workpieces 50 taken in step S206 are placed into the container 60. Steps S206 and S207 correspond to the third operation control. After step S207 is completed, this process is finished.

[0059] On the other hand, if the number of temporarily placed items is less than NM, the response in step S205 is "YES", and the process proceeds to step S208. In step S208, N workpieces 50 are taken from pallet 40. After step S208 is completed, the process proceeds to step S209, where M of the N workpieces 50 taken in step S208 are placed on the temporary placement table 80 for temporary placement. After step S209 is completed, the process proceeds to step S210, where NM of the N workpieces 50 taken in step S208 are placed in container 60. Steps S208 to S210 correspond to the second operation control. After step S210 is completed, this process is finished.

[0060] Next, an example of a specific operation related to pick-and-place work performed by the robot arm 20 with the above configuration will be described with reference to Figures 7 to 10. Note that in Figures 7 to 10, the robot arm 20 is not shown, and only the hand 70 attached to the end of the arm is shown.

[0061] [1] Operation when the first motion control is executed As shown in Figure 7(a), when the set number of items to be loaded is N, the robot arm 20 uses the hand 70 to pick up N workpieces 50 from the pallet 40. Then, as shown in Figure 7(b), the robot arm 20 loads the N workpieces 50 that it has picked up into the container 60.

[0062] [2] Operation when the second operation control is executed As shown in Figure 8(a), when the set input quantity is NM and the number of temporarily placed items is less than NM, the robot arm 20 uses the hand 70 to pick up N workpieces 50 from the pallet 40. In this case, if the number of temporarily placed items at this point is L, the following relationship (1) holds. Note that L is 0 or a positive integer. NM>L …(1)

[0063] Subsequently, as shown in Figure 8(b), the robot arm 20 temporarily places M of the N workpieces 50 that it has removed onto the temporary storage table 80. Then, as shown in Figure 8(c), the robot arm 20 places NM of the N workpieces 50 that it has removed into the container 60.

[0064] [3] Operation when the third control is executed As shown in Figure 9(a), when the set input quantity is NM and the number of temporary placements L is NM, the robot arm 20 uses the hand 70 to pick up NM workpieces 50 from the temporary placement table 80. In this case, if the number of temporary placements at this point is L, the following relationship (2) holds. NM = L …(2)

[0065] Subsequently, as shown in Figure 9(b), the robot arm 20 places the extracted NM workpieces 50 into the container 60. As a result, the number of workpieces 50 temporarily placed on the temporary placement table 80 becomes 0.

[0066] Furthermore, as shown in Figure 10(a), if the set input quantity is NM and the number of temporary placements L is greater than NM, the robot arm 20 uses the hand 70 to pick up NM workpieces 50 from the temporary placement table 80. In this case, if the number of temporary placements at this point is L, the following relationship (3) holds. NM <L …(3)

[0067] Subsequently, as shown in Figure 10(b), the robot arm 20 places the extracted NM workpieces 50 into the container 60. As a result, the number of workpieces 50 temporarily placed on the temporary placement table 80 becomes "L-(NM)".

[0068] According to the embodiment described above, the following effects can be obtained. The robot arm 20 is equipped with a hand 70 that can grasp N workpieces 50, and the container 60 is designed to hold up to N workpieces. In this case, separate from the container 60, there is a temporary storage table 80 that can temporarily hold at least N-1 workpieces 50.

[0069] In the above configuration, the operation control unit 32 executes one of the first operation control, second operation control, or third operation control according to the set input number, which is the number of inputs set by the input number setting unit 31, and the temporary placement number, which is the number of workpieces 50 temporarily placed on the temporary placement table 80. That is, if the set input number is N, the operation control unit 32 executes the first operation control, which involves taking N workpieces 50 from the pallet 40 and putting the taken workpieces 50 into the container 60.

[0070] Furthermore, if the set input quantity is NM and the number of temporarily placed items is less than NM, the operation control unit 32 performs a second operation control in which it takes N workpieces 50 from the pallet 40, temporarily places M of the taken workpieces 50 on the temporary placement table 80, and puts NM of the taken workpieces 50 into the container 60. In addition, if the set input quantity is NM and the number of temporarily placed items is NM or more, the operation control unit 32 performs a third operation control in which it takes NM workpieces 50 from the temporary placement table 80 and puts the taken workpieces 50 into the container 60.

[0071] In this way, regardless of whether the number of inputs is N or NM, that is, regardless of the number of inputs, the number of workpieces 50 taken out of the pallet 40 in one operation will be fixed at N. Thus, with the above configuration and control, since N workpieces are taken out of the pallet 40 in one operation, the work time can be reduced to approximately 1 / N compared to the case where one workpiece is taken out of the pallet each time. Furthermore, in this case, since the pattern of taking out N workpieces 50 is fixed to be taken out each time, it is possible to simplify the processing in the controller 30 related to the taking out of the workpieces 50.

[0072] In the above configuration and control, when the number of inputs is N, that is, when the number of workpieces 50 removed matches the number of inputs, the removed workpieces 50 are placed directly into the container 60, as in the conventional technology. However, in the above configuration and control, when the number of inputs is less than N, that is, when the number of inputs is NM, the number of workpieces 50 removed does not match the number of inputs, so the removed workpieces 50 cannot be placed directly into the container 60, as in the conventional technology. Therefore, in the above configuration and control, when the number of inputs is NM, the number of inputs is adjusted to the desired number by temporarily placing M workpieces 50 out of the removed workpieces 50 on the temporary storage table 80.

[0073] As described above, the workpieces 50 temporarily placed on the temporary storage table 80 are used in the following way. That is, in the above configuration and control, if the number of inputs is NM and the number of temporary placements, which is the number of workpieces 50 temporarily placed on the temporary storage table 80, is NM or more, then NM workpieces 50 are taken out from the temporary storage table 80 instead of the pallet 40, and these taken out workpieces 50 are put into the container 60.

[0074] Furthermore, in this case, the maximum number of workpieces 50 that can be stored in the pallet 40 is an integer multiple of N, and N workpieces are removed in each operation. Therefore, regardless of the number of workpieces initially loaded, the number of remaining workpieces 50 in the pallet 40 can always be reduced to zero by performing a predetermined number of operations. Thus, with the above configuration and control, a situation will never occur where fewer workpieces 50 than the initial load remain in the pallet 40, thus avoiding complexity in the processing of the pallet 40. In this way, this embodiment offers the excellent effect of shortening the working time for the pick-and-place operation—that is, the operation of removing workpieces 50 from the pallet 40 and placing them into the container 60—while simplifying the processing related to workpiece removal.

[0075] In the above configuration, the container 60 is generally placed in a predetermined location, taking into consideration subsequent processes. In this case, the container 60 is divided into grid-like sections for each workpiece 50 to be loaded. Therefore, when loading workpieces 50 into the container 60, if the hand 70 is holding any extra workpieces 50 other than the workpiece 50 to be loaded, these extra workpieces 50 may come into contact with workpieces already placed in the container 60, or with the partitions of the container 60. As a result, the workpieces 50 may be displaced or damaged. Therefore, in this case, the operation control unit 32, in the second operation control, temporarily places M workpieces 50 on the temporary storage table 80, and then loads NM workpieces 50 into the container 60.

[0076] In this way, when loading the workpieces 50 into the container 60, the extra M workpieces 50 out of the N workpieces 50 taken from the pallet 40 are already temporarily placed on the temporary storage table 80, and the hand 70 is holding only the NM workpieces 50 that are to be loaded. Therefore, according to the above control, when loading the workpieces 50 into the container 60, the risk of the extra workpieces 50 coming into contact with workpieces 50 already placed in the container 60, the partitions of the container 60, etc., causing the workpieces 50 to shift position or be damaged can be reduced.

[0077] Furthermore, the temporary placement platform 80 can be arranged more freely than the container 60, and the input area for each workpiece 50 can be made relatively large without partitions. Therefore, with the above control, when temporarily placing M workpieces 50, although the hand 70 is also holding workpieces 50 other than the workpiece 50 being temporarily placed, the possibility of a workpiece 50 coming into contact with already temporarily placed workpieces 50 can be kept sufficiently low by devising the arrangement of the temporary placement platform 80 or by making the input area for each workpiece 50 sufficiently large relative to the size of the workpiece 50.

[0078] <Variations related to the second motion control> In this embodiment, the operation control unit 32 temporarily places M workpieces 50 on the temporary storage table 80 in the second operation control, and then places NM workpieces 50 into the container 60. However, this can be modified as follows. That is, in the second operation control, the operation control unit 32 may place NM workpieces 50 into the container 60, and then temporarily place M workpieces 50 on the temporary storage table 80. This modification can be specifically achieved by changing the execution order of steps S209 and S210 in Figure 11.

[0079] In other words, in this case, the intended action of placing the workpiece 50 into the container 60 is performed prior to the action of temporarily placing the workpiece 50 on the temporary placement stand 80. This way, the number of workpieces to be placed can be adjusted by temporary placement without prolonging the work time required to take the workpiece 50 from the pallet 40 and place it into the container 60, in other words, while maintaining good productivity efficiency.

[0080] <Changes regarding temporary storage locations> In this embodiment, only one temporary storage stand 80, which is an example of a temporary storage location, was provided. However, this can be modified as follows: Multiple temporary storage stands 80 may be provided. In this case, as shown in Figure 12, each of the multiple temporary storage stands 80 will be located on the path from the pallet 40 to the container 60 and at different locations from each other.

[0081] With this configuration, when the second operation control is executed, it becomes possible to use the temporary storage table 80 that provides the shortest path from the pallet 40 to the container 60 via the temporary storage table 80. Specifically, when a workpiece 50 stored on the upper side of the pallet 40 in Figure 12 is removed, the upper temporary storage table 80 is used, and when a workpiece 50 stored on the lower side of the pallet 40 in Figure 12 is removed, the lower temporary storage table 80 is used, thereby making the path from the pallet 40 to the container 60 via the temporary storage table 80 the shortest possible. According to the above modification, the effect is obtained in that the work time, including the temporary storage operation, can be minimized.

[0082] Furthermore, in this embodiment, the temporary storage table 80, which is an example of a temporary storage location, was shaped to allow N-1 workpieces 50 to be arranged in a row, but its shape can be changed as appropriate. For example, the temporary storage table 80 may have an irregular shape as shown in Figure 13. Also, the temporary storage table 80 only needs to be able to temporarily store at least N-1 workpieces 50, and for example, it may be configured to accommodate N workpieces 50 as shown in Figure 14.

[0083] (Other embodiments) It should be noted that the present invention is not limited to the embodiments described above and shown in the drawings, and can be arbitrarily modified, combined, or expanded without departing from its essence. The numerical values ​​and other figures shown in each of the above embodiments are illustrative examples and are not limiting.

[0084] The gripping parts 71 and 72 of the hand 70 are not limited to those equipped with a suction mechanism for adsorbing and holding the workpiece 50; various types can be used, such as those equipped with a chuck for gripping and holding the workpiece 50.

[0085] The present invention is not limited to a controller 30 for a robot arm 20 applied to a production system 10, but can be applied to robot arm control devices in general that control a robot arm that performs the task of picking up workpieces stored on a pallet and placing them in a loading location. [Explanation of Symbols]

[0086] 10...Production system, 20...Robot arm, 30...Controller, 31...Input quantity setting unit, 32...Motion control unit, 40...Pallet, 50...Workpiece, 60...Container, 70...Hand, 80...Temporary storage stand.

Claims

1. A control device for a robot arm that controls a robot arm that performs the task of taking out workpieces stored on a pallet and placing them in a loading location, The robot arm is capable of gripping N workpieces, which are an integer greater than or equal to 2. The aforementioned input location is capable of inputting a maximum of N of the aforementioned workpieces. A temporary storage area is provided, separate from the aforementioned input area, where at least N-1 of the workpieces can be temporarily placed. The maximum number of workpieces that can be stored on the pallet is an integer multiple of N. An input quantity setting unit sets the input quantity, which is the number of workpieces to be placed in the input location, based on an input quantity command given from an external source. An motion control unit controls the movement of the robot arm to remove the workpiece from the pallet and to place the removed workpiece into the input location. Equipped with, The aforementioned operation control unit, Let M be an integer between 1 and N-1, If the number of items to be loaded, as set by the loading quantity setting unit, is N, then the first operation control is executed to take N items of workpieces from the pallet and load the removed workpieces into the loading location. If the number of works to be put in set by the input quantity setting unit is N-M, and the number of works temporarily placed in the temporary storage location is less than N-M, then a second operation control is executed to take N works from the pallet, temporarily place M of those works in the temporary storage location, and put N-M of those works into the input location. A control device for a robot arm that, when the number of works to be put in set by the input number setting unit is N-M and the number of works to be temporarily placed is N-M or more, performs a third operation control to take N-M works from the temporary placement location and put the taken works into the input location.

2. The control device for a robot arm according to claim 1, wherein the motion control unit, in the second motion control, temporarily places M of the workpieces in the temporary storage location, and then loads N-M of the workpieces into the loading location.

3. The control device for a robot arm according to claim 1, wherein the motion control unit, in the second motion control, loads N-M workpieces into the loading location and then temporarily places M workpieces in the temporary storage location.

4. Multiple temporary storage locations are provided. The control device for a robot arm according to any one of claims 1 to 3, wherein each of the plurality of temporary storage locations is located on a path from the pallet to the input location and is provided at a different location from one another.

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