System, system control method, apparatus, apparatus control method, article manufacturing method, control program, and recording medium

Abstract

To reduce energy consumption.SOLUTION: A system that holds an object includes a holding-force generation source and a control apparatus. The control apparatus acquires a control value of the holding-force generation source for holding the object on the basis of the control value of the holding-force generation source in a case where information related to a position of the object has changed, by changing an output of the holding-force generation source.SELECTED DRAWING: Figure 2

Description

[Technical Field]

[0001] The present invention relates to a system and an apparatus. [Background technology]

[0002] In production lines for processing industrial products and autonomous mobile manipulators for pick-and-place operations, vacuum suction, electromagnets, and other mechanisms are used to hold and transport workpieces. Workpiece-holding devices primarily consist of a holding force source that generates a holding force, a holding unit that holds the workpiece, and a transport unit that transports the workpiece. Generally, the holding force is set to a value that allows for a margin of error so that a wide variety of workpieces of different weights can be held and even if there are variations in the holding force due to the material and characteristics of the workpieces or the aging deterioration of the holding unit. In other words, the holding force generated by the holding force source is set higher than necessary to hold the workpiece. However, for example, with lightweight workpieces, an excessively high holding force can be generated, resulting in wasted power consumption by the holding force source. Patent Document 1 proposes a workpiece transport device that includes a mechanism for measuring the deformation of the elastic pad that serves as the workpiece holding unit using a displacement meter or other device. When a workpiece is held at a preset holding force, the device increases the holding force if the deformation of the elastic pad exceeds a specified range. In Patent Document 1, the workpiece is held by suction using an elastic pad, but the preset holding force (initial holding force) is set to a lower value than that of general workpiece holding devices, thereby reducing wasted power consumption. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Japanese Patent Publication No. 2020-185636 Summary of the Invention [Problem to be solved by the invention]

[0004] However, the technology described in Patent Document 1 has the following problems. In Patent Document 1, the holding force is set lower than that of a typical workpiece holding device. As a result, when a workpiece is held at the set holding force, the elastic pad stretches more than usual due to the workpiece's own weight, making the holding state unstable and making the workpiece more likely to fall. Therefore, the amount of stretch of the elastic pad is measured using a displacement meter, and if it exceeds a predetermined threshold, the holding force is deemed insufficient. The holding force setting is then adjusted for each workpiece until the amount of stretch falls below the threshold, i.e., until the minimum holding force required to hold the workpiece is reached. However, for light workpieces, for example, even if the holding force is set lower than that of a typical workpiece holding device, the amount of stretch of the elastic pad may not reach the threshold. In this case, the holding force may be set higher than necessary, leaving room for further reduction in power consumption (energy consumption). [Means for solving the problem]

[0005] The present invention employs a system for holding an object, comprising a holding force generating source and a control device, wherein the control device changes the output from the holding force generating source, thereby obtaining a control value for the holding force generating source when holding the object based on the control value of the holding force generating source when information regarding the position of the object changes. [Effects of the Invention]

[0006] According to the present invention, it is possible to reduce energy consumption. [Brief explanation of the drawings]

[0007] [Figure 1] 1 is a schematic diagram of a system 1000 according to an embodiment. [Figure 2] 3 is a control flowchart according to the embodiment. [Figure 3]10 is a graph showing the holding force of the workpiece W, the position of the workpiece W, and the deformation amount of the suction pad 11 in time series in the embodiment. [Figure 4] 10 is a diagram showing the balance of forces around the workpiece W when setting the holding force for the workpiece W in the embodiment. FIG. [Figure 5] 1 is a schematic diagram of a system 1000 according to an embodiment. [Figure 6] 1 is a schematic diagram of a system 1000 according to an embodiment. [Figure 7] 1 is a schematic diagram of a system 1000 according to an embodiment. DETAILED DESCRIPTION OF THE INVENTION

[0008] Hereinafter, a description will be given of an embodiment of the present invention with reference to the accompanying drawings. The embodiment shown below is merely an example, and those skilled in the art can appropriately modify the detailed configuration, for example, without departing from the spirit of the present invention. Furthermore, the numerical values ​​used in the present embodiment are for reference only and do not limit the present invention. In the following drawings, the arrows X, Y, and Z in the figures indicate the coordinate system of the entire system. Generally, an XYZ three-dimensional coordinate system indicates the world coordinate system of the entire installation environment. In addition, a local coordinate system may be used as appropriate for control purposes, etc.

[0009] (First embodiment) FIG. 1 is a schematic diagram showing a system 1000 according to this embodiment. FIG. 1(a) shows a schematic configuration of the system 1000. FIG. 1(b) shows the flexible range of the suction pad 11. As shown in FIG. 1(a), the system 1000 includes a workpiece holding device 100, a vacuum pressure source 21, and a control device 20. The workpiece holding device 100 is a transport device for transporting the workpiece to the next process. The workpiece holding device 100 includes a workpiece table 10 on which the workpiece is mounted, a suction pad 11 for holding the workpiece, suction holes 13 connected to the suction pad 11, and a transport hand 12 on which the suction pad 11 is mounted. The transport hand 12 is equipped with a displacement sensor 22 capable of measuring information regarding the positions of the transport hand 12 and the workpiece W, and a transport stage 14 for transporting the suction pad 11 in the Z, X, and Y directions.

[0010] The system 1000 also includes a vacuum pressure source 21, such as a vacuum pump or ejector, that generates a suction force in the suction holes 13. The system 1000 also includes an air pressure pipe 15 that connects the transfer stage 14 and the vacuum pressure source 21, and a control device 20 that acquires displacement data from a displacement sensor 22 and controls the output of the vacuum pressure source 21 and the position of the transfer stage 14. As shown in FIG. 1(b), the suction pad 11 is made of an elastic material such as rubber, and has flexibility ranging from its natural length without deflection (right diagram in FIG. 1(b)) to a position where it can no longer bend (left diagram in FIG. 1(b)). This range is therefore referred to as the flexibility range 30 of the suction pad.

[0011] The computer that constitutes the control device 20 has a CPU (Central Processing Unit), ROM (Read Only Memory), and RAM (Random Access Memory). It also includes a communication interface (hereinafter referred to as "I / F") and other components. The CPU, which is a processor, is an example of a control unit. The ROM stores a program. The program causes the computer, i.e., the CPU, to output commands for controlling the transfer stage 14 and the vacuum pressure source 21. The RAM is used to temporarily store programs for controlling the entire system, data such as the execution timing of tasks for each control target, and control commands.

[0012] The CPU acquires data transmitted from the transfer stage 14, the vacuum pressure source 21, and the displacement sensor 22 by receiving it via the I / F. Furthermore, the CPU can transmit commands as control target values ​​via the I / F to the control devices that control each control object based on programs and data input by the user. While the present embodiment describes an example in which the control device 20 directly controls the transfer stage 14 and the vacuum pressure source 21, this is not limiting. For example, the transfer stage 14 and the vacuum pressure source 21 may each be equipped with a control device configured by a computer including a microprocessor, and the control device 20 may output commands to each control device, with the actual control being performed by the equipped control device. In other words, at least one control device may be used to control the system 1000. Communication between the control device 20 and other control objects and control devices may be wired or wireless.

[0013] In this embodiment, the program is recorded in a ROM, but this is not limiting. The program may be recorded on any non-transitory recording medium that is readable by a computer. Examples of recording media that can be used to supply the program to a computer include flexible disks, hard disks, optical disks, magneto-optical disks, magnetic tapes, and non-volatile memories.

[0014] Next, the outline of the operation of the system 1000 will be described. The workpiece W is supplied by various supply devices and placed on the workpiece table 10. The supply devices may be belt conveyors or AGVs (Automated Guided Vehicles). Next, the suction pad 11 is brought close to the workpiece W placed on the workpiece table 10 by the transport stage 14, and abuts against the workpiece W, forming an airtight space between the tip of the suction pad 11 and the workpiece W. Next, vacuum pressure is generated by the vacuum pressure source 21, and the air in the airtight space formed between the tip of the suction pad 11 and the workpiece W is sucked into a vacuum state via the air pressure pipe 15 and the suction hole 13. This generates a holding force that pulls the workpiece W toward the suction pad 11, and the workpiece W is held by the suction pad 11. Then, while maintaining this state, the workpiece W is transported to the next process by the transport stage 14.

[0015] In this way, by placing the workpiece W in a different location and transporting it, it is possible to play a part in the manufacture of an article. Also, a workpiece to be assembled, which is different from the workpiece W, may be placed in a location different from the work table, and the workpiece W may be moved by the suction pad 11 and brought into contact with the workpiece to be assembled, thereby manufacturing an article.

[0016] Next, a method for setting the holding force of the workpiece W in this embodiment will be described. FIG. 2 is a control flowchart in this embodiment. The control flow shown in FIG. 2 is executed by the CPUs of each control device working together through communication. FIG. 3 is a time-series graph showing the holding force setting method. Graph (a) shows the state of the holding force applied to the workpiece W, and graph (b) shows the position of the workpiece W and the deformation of the pad. Also, FIG. 4 shows the balance of forces around the workpiece W when setting the holding force.

[0017] 2, when the operation to set the holding force is started, first in step S1, the control device 20 sets the output of the vacuum pressure source 21, such as a vacuum pump or ejector, to 0 (or a value that can be substantially regarded as 0), and sets the suction pressure to 0 (or a value that can be substantially regarded as 0). This state corresponds to the initial state G1 in FIG. 3 and the initial state P1 (FIG. 4(a)) in FIG. 4, where the suction pad 11 is not in contact with the workpiece W. In this state, the workpiece W is mounted on the workpiece table 10, and therefore the workpiece W is subjected to its own weight mg and a reaction force N from the workpiece table 10.

[0018] Next, in step S2, the control device 20 moves the transfer stage 14 to suction coordinates (X0, Y0, Z0) to bring the suction pad 11 into contact with the workpiece W. This corresponds to the suction pad 11 lowered state G2 in FIG. 3 and to the suction pad 11 lowered state P2 (FIG. 4(b)) in FIG. 4. The suction coordinates X0 and Y0 are set in advance in the control device 20, and are positioned so that the edge of the tip of the suction pad 11 comes into contact with the workpiece W all around, creating an airtight space between the tip of the suction pad 11 and the workpiece W. Z0 is set in advance in the control device 20, and the transfer stage 14 is moved to Z0, so that the amount of deflection of the suction pad 11 when pressed against the workpiece W does not exceed the suction pad's flexible range 30. In addition, the mounting position of the displacement sensor 22 on the transport hand 12 is set in advance so that the probe of the displacement sensor 22 mounted on the transport hand 12 contacts the workpiece W within the measurement range of the displacement sensor 22 at Z0.

[0019] Next, in step S3, the control device 20 starts measurement by the displacement sensor 22, and measures information relating to the position of the workpiece W.

[0020] Next, in step S4, the control device 20 changes the control value of the vacuum pressure source 21, increasing the output of the vacuum pressure source 21 by Δ (delta), thereby increasing the vacuum pressure generated by the vacuum pressure source 21. This state corresponds to the holding force increasing state G3 in FIG. 3 and to the holding force increasing state P3 (FIG. 4(c)) in FIG. 4. Δ is a fixed amount of change for each stage, which is set in advance in the control device 20 and is set to a small amount, such as 1 / 100 or 1 / 50 of the rated output T of the vacuum pump. The holding force pA generated by the vacuum pressure is set to be sufficiently small compared to the weight of the workpiece W.

[0021] Based on this output setting, in step S5, the control device 20 determines whether or not displacement has occurred in the displacement sensor 22. If displacement has occurred in the displacement sensor 22 (details of the state in which displacement has occurred in the displacement sensor 22 will be described later), step S5: YES is used to proceed to the next step. If displacement has not occurred, step S5: NO is used to return to the state immediately before step S4, and the output of the vacuum pressure source 21 is switched to one that is further increased by Δ. In this way, it is confirmed whether or not displacement has occurred in the workpiece W, and step S4 is executed to increase the output of the vacuum pressure source 21 until displacement occurs. If the output of the vacuum pressure source 21 is increased and the resulting holding force pA due to the vacuum pressure exceeds the sum of the weight mg of the workpiece W and the force pressing by the suction pad 11 (elastic force kΔz), the workpiece W is pulled toward the suction pad 11. Then, the workpiece W is separated from the workpiece table 10. Therefore, displacement is detected by the displacement sensor 22, and the process proceeds to step S6. This state corresponds to the workpiece W floating state G4 in FIG. 3 and the workpiece W floating state P4 (FIG. 4(d)) in FIG.

[0022] The balance of forces around the workpiece W at this time will be explained in detail using Figure 4. The mass of the workpiece W is m, the acceleration of gravity is g, the elastic coefficient of the suction pad 11 is k, the amount by which the suction pad 11 is deflected from its natural length is Δz, the suction pressure at the tip of the suction pad is p, the cross-sectional area of ​​the suction pad 11 is A (not shown), and the reaction force that the workpiece W receives from the workpiece table 10 is N. The force that the workpiece W receives from the probe of the displacement sensor 22 is small and will be ignored.

[0023] 4(b), when the suction pad 11 is in the lowered state P2, two forces act downward on the workpiece W: the weight mg of the workpiece and the elastic force kΔz caused by the contact of the suction pad 11. Therefore, the following relationship holds: (Number 1) N=mg+kΔz (1)

[0024] 4(c), the suction pad 11 applies a force equal to the suction pressure p × pad cross-sectional area A to pull in the workpiece W upward, but this force does not exceed the downward force acting on the workpiece, which is its own weight mg and the elastic force kΔz. Therefore, the following relationship holds, and the workpiece W remains placed on the workpiece table 10 and does not float up. (Number 2) pA+N=mg+kΔz (2)

[0025] From this state, the output of the vacuum pressure source 21 is increased, and when the following relationship is met, the workpiece W floats, resulting in a workpiece W floating state P4 in FIG. 4(d). (Number 3) pA>mg+kΔz (3)

[0026] Returning to FIG. 2, in step S6, a control value corresponding to the output of the vacuum pressure source 21 when displacement of the workpiece W is detected in step S5 is acquired as a control value for transporting the workpiece W. This completes the operation for setting the holding force of the workpiece W. While maintaining this output, the workpiece W is transported to the next process by the transport stage 14. Note that instead of acquiring a control value, the output of the vacuum pressure source 21 may be acquired and set. Any format may be used as long as the value can be executed to output the vacuum pressure source 21 when displacement of the workpiece W is detected.

[0027] According to this embodiment, the holding force for the workpiece is set by directly changing the output from the vacuum pressure source, which generates the holding force, and is set based on the timing at which the workpiece is lifted. This makes it possible to set the minimum necessary holding force regardless of the weight of the workpiece, the air permeability of the workpiece, or the amount of air leakage from the suction pad 11. Therefore, the output of the vacuum pressure source 21 can be adjusted to the minimum necessary state, reducing power consumption and enabling energy conservation.

[0028] (Second embodiment) Next, a second embodiment of the present invention will be described in detail. In the above embodiment, the transport hand 12 and the suction pad 11 are moved by the transport stage 14, but this is not limited to this. For example, they may be moved by a robot. In the following, the same reference numerals will be used for components that are the same as or equivalent to those in the first embodiment, and their description will be omitted or simplified. The following description will focus on the differences from the first embodiment.

[0029] Fig. 5 is a diagram that schematically illustrates a system 1000 according to this embodiment. In Fig. 5, the system 1000 includes a robot device 600 and a control device 400 that controls the robot device 600 and a vacuum pressure source 21. An input device 700 can be connected to the control device 400. In Fig. 5, the vacuum pressure source 21, the control device 400, and the input device 700 are shown as blocks.

[0030] The input device 700 may be an operating device such as a teaching pendant, or may be another computer device capable of editing a robot program, such as a PC (Personal Computer) or a server. The input device 700 can be connected to the control device 400 via a wired or wireless communication connection means, and has a user interface function, such as accepting operations of the robot device 600 by a user and displaying the status of the robot device 600.

[0031] The control device 400 is configured by a computer including a microprocessor and the like, and is capable of controlling the robot device 600. As shown in FIG. 1, the computer that constitutes the control device 400 has a CPU, ROM, and RAM. It also includes a communication interface (hereinafter referred to as "I / F") and the like. The CPU, which is a processor, is an example of a control unit.

[0032] The ROM stores a program. The program causes a computer, i.e., a CPU, to execute a method for controlling the robot arm 500 or a method for controlling the vacuum pressure source 21. The RAM is used to temporarily store data such as teaching data input from the input device 700 and control commands. The CPU acquires teaching data transmitted from the input device 700 and data from various sensors mounted on the robot device 600 by receiving the teaching data via the I / F. The CPU can also generate trajectories for each axis of the robot device 600 based on the teaching data and transmit commands as control target values ​​to the robot device 600 via the I / F.

[0033] In this embodiment, the program is recorded in a ROM, but this is not limiting. The program may be recorded on any non-transitory recording medium that is readable by a computer. Examples of recording media that can be used to supply the program to a computer include flexible disks, hard disks, optical disks, magneto-optical disks, magnetic tapes, and non-volatile memories.

[0034] The robot device 600 includes a robot arm 500 and a transport hand 12 disposed on the robot arm 500. The transport hand 12 is attached to a predetermined portion of the robot arm 500, for example, to the tip of the robot arm 500. In FIG. 5 , the transport hand 12 is attached to a link 526. The transport hand 12 has a suction pad 11 capable of holding a workpiece W as an object to be held. The suction pad 11 is connected to a vacuum pressure source 21 via an air pressure pipe 15 and an suction hole 13. The suction pad 11 and the transport hand 12 are connected via the suction hole 13. The interior of the robot arm 500 is connected via the air pressure pipe 15.

[0035] The robot arm 500 is, for example, a vertically articulated robot arm. The robot arm 500 has a link 520, which is a base portion fixed to a workbench or a surface plate, and multiple links 521, 522, 523, 524, 525, and 526 that transmit displacement and force. The multiple links 520 to 526 are connected by multiple joints J1, J2, J3, J4, J5, and J6. This allows each of the links 521 to 526 to turn or rotate at each of the joints J1 to J6.

[0036] Each joint of the robot arm 500 is provided with a motor as a drive source for driving each of these, a reducer, and an encoder as position detection means for detecting the rotation angle of the motor. The encoders may be installed at any position and output method. Control commands are output to each motor based on values ​​from these encoders. By driving each motor, the robot arm 500 can be placed in various postures, the transport hand 12 can be positioned in various positions and postures, and the fingers can be driven to perform work on the workpiece W. Each joint of the robot arm 500 may be provided with a sensor capable of detecting force information.

[0037] With the above configuration, the robot arm 500 can move the transport hand 12 to any position and perform a desired task. For example, the robot arm 500 and the transport hand 12 can move the workpiece W and assemble it by bringing it into contact with another workpiece that is to be assembled. In this way, an article can be manufactured by assembling the workpiece W with another workpiece as a finished product.

[0038] The setting of the holding force for the workpiece W is the same as in the first embodiment. By moving the transport hand 12 with the robot arm 500, the control shown in Figures 2 and 4 can be executed, and the holding force for the workpiece W can be set based on the timing at which the workpiece W floats up.

[0039] According to the present embodiment, the holding force for the workpiece is set by directly changing the output from the vacuum pressure source, which generates the holding force, and is set based on the timing at which the workpiece is lifted. This makes it possible to set the minimum necessary holding force regardless of the weight of the workpiece, the air permeability of the workpiece, or the amount of air leakage from the suction pad 11. Therefore, the output of the vacuum pressure source 21 can be adjusted to the minimum necessary state, reducing power consumption and enabling energy conservation. Furthermore, the various embodiments and modifications described above may be combined and implemented.

[0040] (Third embodiment) Next, a third embodiment of the present invention will be described in detail. In the above-described embodiment, the workpiece W is held by the vacuum pressure source 21 and the suction pad 11, but this is not limited to this. For example, an electromagnetic force source may be used as the holding force generating source. In the following, the same reference numerals will be used for the same or corresponding components as in the above-described embodiment, and their description will be omitted or simplified. The following description will focus on the differences from the first embodiment.

[0041] FIG. 6 is a diagram illustrating a schematic diagram of a system 1000 according to this embodiment. The system differs from the above-described embodiment in that it includes an electromagnetic force source 31, an electromagnet 33, and wiring 32 electrically connecting the electromagnetic force source 31 and the electromagnet 33, and the workpiece W is a magnetic body. The electromagnetic force source 31 is connected to a control device 20, which controls the electromagnetic force source 31 to change the magnetic force of the electromagnet 33, thereby changing the magnetic force holding the workpiece W. The holding force for the workpiece W is set in the same manner as in the first embodiment. The control shown in FIGS. 2 and 4 is executed to move the transport hand 12 and the electromagnet 33 using the transport stage 14, and the holding force for the workpiece W can be set based on the timing at which the workpiece W is levitated.

[0042] According to the present embodiment, the holding force for the workpiece is set by directly changing the output from the electromagnetic force source, which generates the holding force, and is set based on the timing at which the workpiece is lifted. This makes it possible to set the minimum necessary holding force. Therefore, the output of the electromagnetic force source 31 can be adjusted to the minimum necessary state, reducing power consumption and enabling energy conservation. Furthermore, the various embodiments and modifications described above may be combined and implemented.

[0043] (Fourth embodiment) Next, a fourth embodiment of the present invention will be described in detail. In this embodiment, an electrostatic force source may be used as the holding force source. In the following, the same reference numerals will be used for the same or corresponding components as those in the above-described embodiments, and their description will be omitted or simplified. The following description will focus on the differences from the first embodiment.

[0044] FIG. 7 is a schematic diagram of a system 1000 according to this embodiment. This system differs from the previous embodiment in that it includes an electrostatic force source 41, a static electricity generator 43, and wiring 42 electrically connecting the electrostatic force source 41 and the static electricity generator 43. The workpiece W is lightweight enough to be held by static electricity, such as paper. The electrostatic force source 41 is connected to a control device 20, which controls the electrostatic force source 41 to change the electrostatic force generated by the static electricity generator 43, thereby changing the holding force of the workpiece W due to the electrostatic force. The holding force for the workpiece W is set in the same manner as in the first embodiment. The transfer stage 14 moves the transfer hand 12 and the static electricity generator 43, and the control shown in FIGS. 2 and 4 is executed, allowing the holding force for the workpiece W to be set based on the timing at which the workpiece W is lifted.

[0045] According to the present embodiment, the holding force for the workpiece is set by directly changing the output from the electrostatic force source, which generates the holding force, and is set based on the timing at which the workpiece is lifted. This makes it possible to set the minimum necessary holding force. Therefore, the output of the electrostatic force source 41 can be adjusted to the minimum necessary state, reducing power consumption and enabling energy conservation. Furthermore, the various embodiments and modified examples described above may be combined and implemented.

[0046] (Other embodiments) The processing procedures of the above-described embodiments are specifically executed by the CPUs of the respective control devices. Therefore, it is also possible to configure the system to read and execute a software control program capable of executing the above-described functions from a recording medium. In this case, the control program itself read from the recording medium will realize the functions of the above-described embodiments, and the control program itself and the recording medium on which the control program is recorded constitute the present invention.

[0047] In addition, in each embodiment, the computer-readable recording medium is a ROM, a RAM, or a flash ROM, and the program is stored in the ROM, the RAM, or the flash ROM. However, the present invention is not limited to this embodiment. The program for implementing the present invention may be recorded on any computer-readable recording medium, such as an SSD (Solid State Drive).

[0048] Furthermore, the workpiece W may have any shape as long as it has a surface that can be held by the suction pad 11, electromagnet 33, and static electricity generator 43. The workpiece W is held during transport by the holding force generated by each holding unit, but this does not limit the shape of the workpiece during transport. Appropriate selection can be made depending on the size, shape, and material of the workpiece. For example, a method such as electromagnetic chuck holding can also be selected. In this case, for example, the shape of the workpiece on the suction pad 11 side is not limited to a surface, and is not limited as long as it can be held by each selected method.

[0049] Furthermore, in each embodiment, the displacement sensor 22 is a contact-type sensor that is mounted on the transport hand 12 and that makes contact with the workpiece W to measure, but this does not limit the form in which information regarding the position of the workpiece is measured. As long as it is possible to detect a change in the position of the workpiece W, the location to be measured does not have to be the workpiece W itself; for example, the displacement of the rubber portion of the suction pad 11 that is in contact with the workpiece W may be measured. Furthermore, the sensor does not have to be a contact-type sensor, and a non-contact sensor such as a laser displacement meter, a capacitance displacement meter, or an eddy current displacement meter may also be used. Furthermore, the displacement sensor 22 may also be mounted on the workpiece table 10 instead of the transport hand 12.

[0050] Furthermore, information regarding the position of the workpiece W can be detected from information other than displacement. For example, the workpiece W and the workpiece table 10 on which the workpiece W is placed can be made of conductive materials, the electrical resistance between the workpiece table 10 and the workpiece W can be measured, and a change in the electrical resistance can be detected when the position of the workpiece W changes. Alternatively, a weighing scale can be built into the workpiece table 10 to measure the weight of the workpiece W, and a change in the weight data measured by the weighing scale can be detected when the position of the workpiece W changes.

[0051] In addition, in each embodiment, when setting the holding force for the workpiece W, the output of the holding force generating source is initially reduced to 0, but the initial holding force should be weak enough against the weight of the workpiece so that the workpiece does not float, so it is acceptable to set the output to be greater than 0.

[0052] In addition, in each embodiment, when setting the holding force of the workpiece W, the output of the holding force generating source is increased in stages by Δ, but since it is only necessary to detect the displacement when the workpiece W floats, the output may also be increased continuously.

[0053] Furthermore, in each embodiment, the holding force for the workpiece W is set to the holding force immediately after the workpiece W is lifted, but this is not limited to this. For example, to reduce concerns about the workpiece W falling due to inertial force caused by acceleration during subsequent transport or shifting of the holding position, the holding force may be set by adding or multiplying a predetermined amount so that an extra holding force capable of withstanding these is added.

[0054] In addition, in the various embodiments described above, the robot arm 500 has been described as a multi-joint robot arm having multiple joints, but the number of joints is not limited to this. Although a vertical multi-axis configuration has been shown as the type of robot arm, a configuration equivalent to the above can also be implemented with different types of joints, such as a horizontal multi-joint type, a parallel link type, or an Cartesian robot.

[0055] Furthermore, the various embodiments described above can be applied to machines that can automatically perform movements such as extension and contraction, bending and stretching, up and down movement, left and right movement, or rotation, or a combination of these movements, based on information stored in a memory device provided in the control device.

[0056] The present invention is not limited to the above-described embodiments, and many modifications are possible within the technical concept of the present invention. Furthermore, the effects described in the embodiments of the present invention are merely a list of the most preferable effects resulting from the present invention, and the effects of the present invention are not limited to those described in the embodiments of the present invention. Furthermore, the above-described various embodiments and modifications may be combined and implemented.

[0057] The disclosure of this embodiment also includes the following configurations and methods.

[0058] (Item 1) 1. A system for holding an object, comprising: A holding force source; a control device; the control device acquires a control value of the holding force generation source when holding the object based on a control value of the holding force generation source when information about the position of the object has changed by changing an output from the holding force generation source; A system characterized by:

[0059] (Item 2) In the system according to item 1, the control device acquires, based on the timing at which the object is floated, the control value of the holding force generation source when holding the object. A system characterized by:

[0060] (Item 3) In the system according to item 1 or 2, a holding portion that comes into contact with the object, the control device causes the holding force generation source to generate a holding force while the holding unit is in contact with the object, thereby changing information about the position of the object; A system characterized by:

[0061] (Item 4) In the system according to item 3, the control device brings the holding unit into contact with the object when the holding force generated by the holding force generation source is 0 or a value that can be regarded as 0. A system characterized by:

[0062] (Item 5) In the system according to item 3 or 4, The holding portion is a suction pad. A system characterized by:

[0063] (Item 6) In the system according to item 5, When the control device brings the suction pad into contact with the object, the amount of deflection of the suction pad is set within a flexible range of the suction pad. A system characterized by:

[0064] (Item 7) In the system according to any one of items 1 to 6, the control device changes the information about the position of the object by changing the holding force generated by the holding force generation source stepwise or continuously; A system characterized by:

[0065] (Item 8) In the system according to any one of items 1 to 7, When the control device changes the holding force generated by the holding force generation source in a stepwise manner, the amount of change in the holding force in one step is set to a holding force that does not change information about the position of the object. A system characterized by:

[0066] (Item 9) In the system according to any one of items 1 to 8, a displacement sensor for acquiring information about the position of the object; The displacement sensor is at least one of a contact sensor that brings a probe into contact with the object, a sensor that measures the displacement of a holder that holds the object, a laser displacement meter, a capacitance displacement meter, an eddy current displacement meter, a sensor that acquires an electrical resistance value between the object and a table on which the object is placed, and a sensor that acquires the weight of the object. A system characterized by:

[0067] (Item 10) In the system according to item 9, a table on which the object is placed, The displacement sensor is provided on the holder or the base. A system characterized by:

[0068] (Item 11) In the system according to any one of items 1 to 10, the control device acquires a value obtained by adding or multiplying a predetermined value to the control value of the holding force generation source when the information regarding the position of the object has changed, as the control value of the holding force generation source when holding the object; A system characterized by:

[0069] (Item 12) In the system according to any one of items 1 to 11, a holding portion for holding the object, The holding unit is moved by a transfer stage or a robot. A system characterized by:

[0070] (Item 13) In the system according to any one of items 1 to 11, The holding force generating source is at least one of a vacuum pressure source, an electromagnetic force source, and an electrostatic force source. A system characterized by:

[0071] (Item 14) A method for controlling a system for holding an object, the system comprising: a holding force generating source; and a control device; the control device acquires a control value of the holding force generation source when holding the object based on a control value of the holding force generation source when information about the position of the object has changed by changing an output from the holding force generation source; A control method comprising:

[0072] (Item 15) A device for holding an object, the device comprising: a control unit; the control unit acquires a control value of the holding force generation source when holding the object based on a control value of the holding force generation source when information about the position of the object has changed by changing an output from the holding force generation source. An apparatus characterized in that

[0073] (Item 16) 1. A method of controlling an apparatus for holding an object, the apparatus comprising: the control unit acquires a control value of the holding force generation source when holding the object based on a control value of the holding force generation source when information about the position of the object has changed by changing an output from the holding force generation source. A control method comprising:

[0074] (Item 17) A method for manufacturing an article, comprising manufacturing the article using the system according to any one of items 1 to 13 or the apparatus according to item 15.

[0075] (Item 18) 18. A control program that can execute the control method according to item 15 or 17 by a computer.

[0076] (Item 19) Item 19. A computer-readable recording medium storing the control program according to item 18. [Explanation of symbols]

[0077] 10 Work table 11 Suction pad 12 Transport hand 13 Adsorption hole 14 Transfer stage 15 Pneumatic piping 20,400 control device 21 Vacuum pressure source 22 Displacement Sensor 30 Adsorption pad flexibility range 31 Electromagnetic power source 32, 42 Wiring 30 Electromagnet 41 Electrostatic Power Source 43 Static electricity generating part 100 Work holding device 500 Robot Arm 520, 521, 522, 523, 524, 525, 526 Links 600 Robotic Devices 700 Input Device double work J1, J2, J3, J4, J5, J6 joints

Claims

1. 1. A system for holding an object, comprising: A holding force source; a control device; the control device acquires a control value of the holding force generation source when holding the object based on a control value of the holding force generation source when information about the position of the object has changed by changing an output from the holding force generation source; A system characterized by:

2. 10. The system of claim 1, the control device acquires, based on the timing at which the object is floated, the control value of the holding force generation source when holding the object. A system characterized by:

3. 10. The system of claim 1, a holding portion that comes into contact with the object, the control device causes the holding force generation source to generate a holding force while the holding unit is in contact with the object, thereby changing information about the position of the object; A system characterized by:

4. 4. The system of claim 3, the control device brings the holding unit into contact with the object when the holding force generated by the holding force generation source is 0 or a value that can be regarded as 0. A system characterized by:

5. 4. The system of claim 3, The holding portion is a suction pad. A system characterized by:

6. 6. The system of claim 5, When the control device brings the suction pad into contact with the object, the amount of deflection of the suction pad is set within a flexible range of the suction pad. A system characterized by:

7. 10. The system of claim 1, the control device changes the information about the position of the object by changing the holding force generated by the holding force generation source stepwise or continuously; A system characterized by:

8. 10. The system of claim 1, When the control device changes the holding force generated by the holding force generation source in a stepwise manner, the amount of change in the holding force in one step is set to a holding force that does not change information about the position of the object. A system characterized by:

9. 10. The system of claim 1, a displacement sensor for acquiring information about the position of the object; The displacement sensor is at least one of a contact sensor that brings a probe into contact with the object, a sensor that measures the displacement of a holder that holds the object, a laser displacement meter, a capacitance displacement meter, an eddy current displacement meter, a sensor that acquires an electrical resistance value between the object and a table on which the object is placed, and a sensor that acquires the weight of the object. A system characterized by:

10. 10. The system of claim 9, a table on which the object is placed, The displacement sensor is provided on the holder or the base. A system characterized by:

11. 10. The system of claim 1, the control device acquires a value obtained by adding or multiplying a predetermined value to the control value of the holding force generation source when the information regarding the position of the object has changed, as the control value of the holding force generation source when holding the object; A system characterized by:

12. 10. The system of claim 1, a holding portion for holding the object, The holding unit is moved by a transfer stage or a robot. A system characterized by:

13. 10. The system of claim 1, the holding force generating source is at least one of a vacuum pressure source, an electromagnetic force source, and an electrostatic force source; A system characterized by:

14. A method for controlling a system for holding an object, the system comprising: a holding force generating source; and a control device; the control device acquires a control value of the holding force generation source when holding the object based on a control value of the holding force generation source when information about the position of the object has changed by changing an output from the holding force generation source; A control method comprising:

15. A device for holding an object, the device comprising: a control unit; the control unit acquires a control value of the holding force generation source when holding the object based on a control value of the holding force generation source when information about the position of the object has changed by changing an output from the holding force generation source. An apparatus characterized in that

16. 1. A method of controlling an apparatus for holding an object, the apparatus comprising: the control unit acquires a control value of the holding force generation source when holding the object based on a control value of the holding force generation source when information about the position of the object has changed by changing an output from the holding force generation source. A control method comprising:

17. A method for manufacturing an article, comprising manufacturing the article using the system according to any one of claims 1 to 13 or the apparatus according to claim 15.

18. A control program that enables a computer to execute the control method according to claim 15 or 16.

19. A computer-readable recording medium storing the control program according to claim 18.

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