Robotic system and robot

Abstract

A robot system has: a chuck that attracts an electrically conductive workpiece using a fluid effect; at least three electrodes that are provided to the chuck; and an electrical property measurer that measures an electrical property of an electrical circuit formed by contact of any two of the electrodes with the workpiece.

Description

TECHNICAL FIELD

[0001] The present application relates to a robot technology, and more particularly, to a robot system and a robot capable of performing workpiece take-out detection with few restrictions. BACKGROUND

[0002] As a robot for pick and place, various robots such as a multi-finger gripping type, an electromagnetic suction type, a vacuum suction type, and a Bernoulli type are known. In the case where such a robot is used to take out a sheet-like, air-permeable workpiece such as a web, the multi-finger gripping type robot can not be able to take out the workpiece because the workpiece has no wall thickness. For the electromagnetic suction type robot, the workpiece is limited to a magnetic body. For the vacuum suction type robot, the vacuum pressure between the robot and the workpiece can not be maintained due to air leakage, and thus the workpiece can not be sucked. Thus, in the case of such a sheet-like, air-permeable workpiece, the Bernoulli type robot that sucks the workpiece using negative pressure generated by ejecting compressed air is generally used. As a technology related to such a robot, the following described contents are known.

[0003] In Patent Literature 1, a device for taking out / holding an air-permeable workpiece is described, which sucks and takes out an air-permeable workpiece in a non-contact manner using suction force generated by ejecting compressed air from a compressed air ejecting nozzle, and holds the taken-out air-permeable workpiece by vacuum suction of a vacuum suction nozzle, whereby a plurality of stacked air-permeable workpieces can be taken out one by one and the air-permeable workpiece can be reliably held by vacuum suction.

[0004] In Patent Literature 2, the following is described: in a separating device that makes a stack of sheet-like magnetic materials float and separate in an electromagnetic suction manner, a vortex type thickness detection mechanism is provided, which is configured adjacent to one side end surface of the sheet-like magnetic material with an excitation coil for generating a high frequency magnetic field, and is configured adjacent to the other side end surface facing the sheet-like magnetic material with a detection coil for detecting impedance of the sheet-like magnetic material.

[0005] In Patent Literature 3, the following is described: in an antistatic method for a photomask, in order to monitor and detect a situation where two conductive pins are punched into the photomask and reach a conductive film using a resistance meter, a resistance detection pin connected to the resistance meter is provided in parallel to a suction plate, and when the conductive pin is suctioned to the suction plate, the resistance detection pin is electrically contacted with the conductive pin.

[0006] PRIOR ART DOCUMENTS

[0007] PATENT LITERATURE

[0008] Patent Literature 1: Japanese Patent Application Laid-Open No. 2003-54774

[0009] Patent Literature 2: Japanese Patent Application Laid-Open No. 2010-254438

[0010] Patent Literature 3: Japanese Patent Application Laid-Open No. H11-67647 SUMMARY

[0011] PROBLEMS TO BE SOLVED BY THE INVENTION

[0012] When a workpiece is taken out by a robot, there are cases where the workpiece cannot be taken out, cases where the workpiece can be taken out but a plurality of workpieces are taken out, cases where the workpiece can be taken out but a holding state is poor, and the like. In such a workpiece taking-out detection (detection of the number of taken-out workpieces, detection of a holding state, and the like), an electromagnetic induction type sensor, an image recognition sensor, and the like can be used, but there are problems as described later, and sometimes application cannot be made.

[0013] An electromagnetic induction type contact sensor generates a magnetic field to magnetize a workpiece, and takes out the workpiece by measuring a magnetic flux of a magnetic field generated by the workpiece, but the workpiece is limited to a magnetic body. In addition, it is suitable for a workpiece having a flat surface with good adhesiveness to the sensor, but it cannot accurately measure a workpiece having poor adhesiveness such as a workpiece having a wrinkle or a workpiece having a concave-convex. In addition, with regard to a double head type electromagnetic induction type non-contact sensor, a workpiece is inserted between an N pole and an S pole of a magnet to generate an eddy current in the workpiece, and a magnetic flux of a magnetic field generated by the eddy current is measured, but the workpiece is limited to a flat plate workpiece.

[0014] On the other hand, with regard to an image recognition sensor such as a camera, it is necessary to switch parameters for image recognition and error determination depending on the shape of a workpiece and the environment around the workpiece, and thus it becomes troublesome. In addition, in the case of a flat workpiece, if the workpieces are in close contact with each other in a state where the outer shapes thereof are identical, it is sometimes difficult to determine whether it is one workpiece or a plurality of workpieces. Furthermore, the image recognition sensor makes the entire system expensive, and makes the robot system high-cost.

[0015] Therefore, a robot technology capable of implementing a workpiece taking-out detection with less limitation is sought.

[0016] SOLUTION TO THE PROBLEM

[0017] One embodiment of the present disclosure provides a robot system including: a chuck that attracts an electrically conductive workpiece using a fluid effect; at least three electrodes provided to the chuck; and an electrical property measurer that measures an electrical property of an electrical circuit formed by contact of any two of the electrodes with the workpiece.

[0018] Another aspect of the present disclosure provides a robot hand including: a chuck that attracts an electrically conductive workpiece using a fluid effect; and an electrode that protrudes from an attracting surface of the chuck and is capable of floating in accordance with contact with the workpiece.

[0019] Another aspect of the present disclosure provides a robot hand including: a chuck that attracts an electrically conductive workpiece using a fluid effect; at least three electrodes that are provided to the chuck; and a rotary contact that is capable of switching a contact point to any two of the electrodes.

[0020] Effects of Invention

[0021] According to one aspect of the present disclosure, the robot hand includes at least three electrodes, thereby enabling detection of a holding state of the workpiece. In addition, an electrical characteristic of an electrical circuit formed by contact of any two electrodes with the workpiece is measured, thereby also enabling detection of the number of workpieces taken out. Since the workpieces are detected by measuring the electrical characteristic, the workpieces are not limited to magnetic bodies, but are electrically conductive bodies. Furthermore, even if the workpieces are in close contact with each other in a state in which the shapes thereof are identical, detection of the workpieces taken out can be performed. Thus, detection of the workpieces taken out (detection of the number of workpieces taken out, detection of the holding state, and the like) can be performed with less restriction.

[0022] According to another aspect of the present disclosure, the electrode protrudes from the chuck, thereby enabling detection of the workpieces taken out even in a Bernoulli-type robot hand that holds the workpieces in a non-contact manner. In addition, even in a workpiece having poor adhesion such as a workpiece having a wrinkle or a workpiece having unevenness, since the electrode is capable of floating in accordance with the shape of the workpiece, detection of the workpieces taken out can be performed with less restriction.

[0023] According to another aspect of the present disclosure, since the rotary contact is capable of switching the contact point to any two electrodes, even if the number of electrodes increases, an electrical characteristic value between any electrodes can be measured using only one electrical characteristic measurer. Furthermore, detection of the workpieces taken out can be performed with less restriction. BRIEF DESCRIPTION OF DRAWINGS

[0024] Figure 1 FIG. 1 is a perspective view showing a robot hand system and a robot hand according to one embodiment.

[0025] Figure 2A FIG. 4 is a bottom view showing a bottom surface of a chuck according to one embodiment.

[0026] Figure 2B FIG. 6 is a partial cross-sectional view showing a cross section of the chuck according to one embodiment.

[0027] Figure 3A FIG. 8 is a partial cross-sectional view showing a cross section of a chuck including face-to-face electrodes. FIG. 9 is a partial cross-sectional view showing a cross section of a chuck including face-to-face electrodes.

[0028] Figure 3B is a partial sectional view showing a cross section of a chuck provided with a protruding and floatable electrode.

[0029] Figure 4 is a block diagram showing an example of a control structure of a robot system.

[0030] Figure 5 is a block diagram showing an example of an electric circuit in a case where the electrode is three.

[0031] Figure 6 is a flowchart showing an example of an operation of a robot system.

[0032] Figure 7 is a block diagram showing an example of an electric circuit in a case where the electrode is four.

[0033] Figure 8 is a top view showing an example of a structure of a rotary contact in a case where the electrode is three.

[0034] Figure 9 is a top view showing an example of an operation of a rotary contact in a case where the electrode is three.

[0035] Figure 10 is a top view showing an example of a structure of a rotary contact in a case where the electrode is four.

[0036] Figure 11 is a top view showing an example of an operation of a rotary contact in a case where the electrode is four. DETAILED DESCRIPTION

[0037] Embodiments of the present disclosure will be described below in detail with reference to the accompanying drawings. In the drawings, the same or similar components are denoted by the same or similar reference numerals. In addition, the embodiments described below do not limit the technical scope of the invention described in the claims or the meanings of terms.

[0038] Figure 1The robotic arm system 1 of this embodiment is shown. The robotic arm system 1 includes a robotic arm 10 for removing a workpiece W and a conveying device 20 for conveying the removed workpiece W to a predetermined position. The workpiece W can be a conductive workpiece, such as a breathable workpiece like a metal mesh, or a non-breathable workpiece like a conductive film for a touch panel. The workpiece W can be a sheet-like workpiece without wall thickness, but if it is a relatively lightweight workpiece, it can also be a workpiece with wall thickness. The workpiece W is stacked on the mounting device 50, but stacking is not necessary. The mounting device 50 can be a fixed workpiece storage container, or it can be a movable mounting device such as a conveyor, shuttle, or unmanned transport vehicle. The robotic arm 10 is a Bernoulli-type robotic arm that uses the Bernoulli effect to attract the workpiece W, but it can also be a vacuum suction type robotic arm. The robotic arm 10 includes a palm portion 11 mounted on the end of the conveying device 20 and a suction cup 12 fixed to the palm portion 11 and using a fluid effect to attract the workpiece W. The robotic arm 10 also includes an electrical characteristic measuring device 16 and at least three electrodes 13 disposed on the suction cup 12 (see reference). Figure 2A and Figure 2B The electrical characteristic measuring device 16 measures the electrical characteristics of the electrical circuit formed by the contact of any two of the electrodes 13 with the workpiece W. The conveying device 20 is an industrial robot such as a multi-joint robot or a parallel link robot, but it can also be a conveying device such as a loader, shuttle, or unmanned transport vehicle.

[0039] Figure 2A The bottom surface of suction cup 12 is shown. Figure 2B Show Figure 2A The suction cup 12 has an AA-line cross-section. In the case of a Bernoulli-type manipulator, the suction cup 12 can be a non-contact suction cup equipped with a nozzle 12a that ejects fluids such as compressed air. In the case of a vacuum suction manipulator, the suction cup 12 can be an suction cup equipped with a nozzle for generating vacuum pressure between itself and the workpiece. In the Bernoulli-type case, a plurality of nozzle holes 12b are evenly spaced on the side circumferential surface of the nozzle 12a. Fluids such as compressed air are ejected from the nozzle holes 12b in the outward circumferential direction to create a negative pressure area below the nozzle 12a that is lower than atmospheric pressure. As a result, the suction cup 12 attracts the workpiece in a non-contact manner.

[0040] Electrode 13 is connected to electrical characteristic measuring instrument 16 via wire 14 (see reference). Figure 1 The electrodes 13 are connected separately. The electrical characteristic measuring device 16 measures the electrical characteristics of the electrical circuit formed by the contact between any two electrodes 13 and the workpiece. The electrical characteristics can be, for example, resistance, but also conductivity, current, etc. By measuring the electrical characteristics, the number of workpieces removed can be detected. For example, when removing one sheet... Figure 1In the case of the metal mesh workpiece shown, the resistance is approximately 0.8Ω; when two sheets are removed together, the resistance is approximately 0.4Ω; and when three sheets are removed together, the resistance is approximately 0.3Ω. That is, the more sheets there are, the lower the resistance (or the higher the conductivity or current), thus enabling the detection of the number of workpieces removed.

[0041] Electrodes 13 can be arranged at equal intervals along the circumference of the suction cup 12, particularly along the outer circumference of the nozzle 12a. By having at least three electrodes 13, it is possible to detect whether the workpiece is held properly. For example, if the workpiece can be detected in any combination of electrodes 13, it can be determined that the workpiece is held properly; if the workpiece can be detected in some combinations of electrodes 13, it can be determined that the workpiece is held improperly; and if the workpiece cannot be detected in any combination of electrodes 13, it can be determined that the workpiece has not been removed. Since workpiece removal detection (detection of the number of removals, detection of holding status, etc.) can be performed by measuring electrical characteristics in this way, the workpiece is not limited to a magnetic material and can be a conductive material. Furthermore, workpiece removal detection can be performed even when the workpieces are pressed together in a state where their shapes are identical. Therefore, workpiece removal detection can be implemented with fewer limitations.

[0042] The robot arm 10 may also include a position displacement suppression pad 15 to suppress positional displacement of the workpiece when it is attracted. The position displacement suppression pad 15 may be formed of a soft material such as soft rubber or sponge, and has a surface roughness or a high coefficient of friction that prevents relative movement of the workpiece. The surface 15a of the position displacement suppression pad 15 preferably protrudes from the attraction surface 12c of the suction cup 12. Thus, lateral displacement of the workpiece relative to the suction cup 12 can be suppressed without damaging the workpiece.

[0043] The tip of electrode 13 can protrude at least from the suction surface 12c of suction cup 12, or, if position offset suppression pad 15 is provided, from the surface 15a of position offset suppression pad 15. Thus, even a Bernoulli-type robot that holds a workpiece in a non-contact manner can perform workpiece removal detection. Furthermore, in the case of a vacuum suction robot that holds a workpiece by adsorption, the tip of electrode 13 can be positioned so that it aligns with the suction surface 12c of suction cup 12 or the surface 15a of position offset suppression pad 15.

[0044] Furthermore, it is preferable that the electrode 13 can float upon contact with the workpiece. For example, an electrode cylinder 13a can be prepared to store the electrode 13, a spring 13b can be arranged in the electrode cylinder 13a and force can be applied to the electrode 13 by the spring 13b, and the electrode cylinder 13a can be locked to the side wall of the suction cup 12 by the locking member 13c, so that the electrode 13 protrudes from the suction surface 12c of the suction cup 12 or the surface 15a of the position displacement suppression pad 15. Thus, upon contact between the electrode 13 and the workpiece, the electrode 13 is retracted into the suction cup 12 while being forceped by the spring 13b (i.e., floated), thereby bringing the workpiece into contact with both the electrode 13 and the position displacement suppression pad 15. For workpieces with poor fit, such as those with wrinkles or unevenness, the electrode 13 can float according to the shape of the workpiece, thus allowing for workpiece removal detection with fewer restrictions.

[0045] Figure 3A A partial cross-section of the suction cup 12 with face-to-face electrodes 13 is shown. Figure 3B A partial cross-section of a suction cup 12 with protruding and buoyant electrodes 13 is shown. (Example) Figure 3A As shown, regarding the electrode 13, which is positioned in a manner consistent with the suction surface 12c of the suction cup 12 or the surface 15a of the position offset suppression pad, the electrode 13 sometimes does not contact the workpiece W, which has wrinkles. In this case, it is impossible to perform workpiece W removal detection. On the other hand, as Figure 3B As shown, regarding the electrode 13, which protrudes from the suction surface 12c of the suction cup 12 or the surface 15a of the position offset suppression pad and can float in the direction of the arrow, even for workpieces W with poor fit such as wrinkles or unevenness, the electrode 13 can float according to the shape of the workpiece, thus enabling the detection of workpiece removal.

[0046] Figure 4 An example of the control structure of the robotic arm system 1 is shown. The robotic arm system 1 also includes a control device 30 for controlling the robotic arm 10 and the conveying device 20. The control device 30 is a computer device equipped with a processor or semiconductor integrated circuit such as a CPU (central processing unit), FPGA (field-programmable gate array), or ASIC (application-specific integrated circuit). The control device 30 includes: a determination unit 31, which determines the removal detection of the workpiece (detection of the number of removals, detection of the holding state, etc.) based on electrical characteristics; a fluid control unit 33, which controls the fluid adjustment device 17 based on the determination result of the determination unit 31; and a conveying control unit 32, which controls the conveying device 20 based on the determination result of the determination unit 31.

[0047] For example, the determination unit 31 can determine the number of workpieces to be removed by comparing the measured value of the electrical characteristics between any two electrodes 13 with the reference value, and determine whether the workpiece is in good condition by combining the comparison of the measured value of the electrical characteristics between any two electrodes 13 with the reference value. Figure 5 An example of an electrical circuit with three electrodes is shown. In this example, the robot arm 10 is equipped with three electrical characteristic measuring devices: a first electrical characteristic measuring device 16 measures the electrical characteristic value between electrodes AB (first characteristic value), a second electrical characteristic measuring device 16 measures the electrical characteristic value between electrodes BC (second characteristic value), and a third electrical characteristic measuring device 16 measures the electrical characteristic value between electrodes CA (third characteristic value). Furthermore, it should be noted that... Figure 5 In the diagram, thick solid lines represent wires on the positive side, and thin solid lines represent wires on the negative side. The first to third characteristic values ​​are appropriately read and used by the control device 30 (determination unit 31). For example, the determination unit 31 can use the first to third characteristic values ​​to determine the number of workpieces removed and whether the workpiece holding state is good, according to the logic determination formula shown in the table below.

[0048] [Table 1]

[0049]

[0050] Refer again Figure 4 The fluid control unit 33 can issue an adjustment command for the fluid pressure or flow rate to the fluid adjustment device 17 based on the number of workpieces removed detected by the determination unit 31. The fluid adjustment device 17 can be, for example, a solenoid valve capable of adjusting the fluid pressure or flow rate, and can be mounted on an air pipe connected to the suction cup. The fluid adjustment device 17 adjusts the fluid pressure or flow rate based on the adjustment command from the fluid control unit 33. For example, the fluid adjustment device 17 can decrease the fluid pressure or flow rate when multiple removals are detected, and increase the fluid pressure or flow rate when zero removals are detected. The fluid adjustment device 17 can repeatedly adjust the flow pressure or flow rate until only one workpiece remains.

[0051] The transport control unit 32 can issue an adjustment command for the transport speed of the workpiece to the transport device 20 based on whether the workpiece holding state is good, as detected by the determination unit 31. The transport device 20 adjusts the transport speed of the workpiece based on the adjustment command from the transport control unit 32. For example, the transport device 20 may decrease the transport speed of the workpiece when a poor holding state is detected, and increase the transport speed of the workpiece when a good holding state is detected.

[0052] Figure 6An example of the operation of the robotic arm system is shown. First, as a preparation, according to the type of each workpiece, (1) the reference characteristic value of the electrical circuit formed by the contact of any two electrodes 13 with a workpiece is measured and set in the control device 30 (determination unit 31), and (2) the reference flow pressure or reference flow rate required to attract a workpiece is measured and set in the control device 30 (determination unit 31).

[0053] In step S10, the operator inputs the workpiece type number into the control device 30, whereby the control device 30 reads the preset reference characteristic value and the reference flow pressure or reference flow rate. In step S11, the control device 30 moves the conveying device 20 above the workpiece. In step S12, the control device 30 lowers the conveying device 20 and moves it to the workpiece removal position. In step S13, the control device 30 adjusts the fluid adjustment device 17 to the reference flow pressure or reference flow rate corresponding to the workpiece type number and generates a suction force.

[0054] In step S14, the control device 30 determines the number of workpieces removed based on the electrical characteristics between any two electrodes 13. If zero workpieces are detected removed in step S14, the process proceeds to step S15, where the fluid adjustment device 17 increases the fluid pressure or flow rate to enhance the attraction of the workpieces. If multiple workpieces are detected removed in step S14, the process proceeds to step S16, where the fluid adjustment device 17 decreases the fluid pressure or flow rate to reduce the attraction of the workpieces. Then, the process returns to step S14, and the control device 30 again determines the number of workpieces removed based on the electrical characteristics between any two electrodes 13. Steps S14 to S16 are repeated until one workpiece is removed.

[0055] If one item is detected to have been removed in step S14, the process proceeds to step S17, where the control device 30 determines whether the workpiece's holding state is good based on the combination of electrical characteristics between any two electrodes 13. If a poor holding state is detected in step S17, the process proceeds to step S18, where the conveying device 20 reduces the workpiece's conveying speed to prevent it from being shaken off during conveying. If a good holding state is detected in step S17, the process proceeds to step S19, where the conveying device 20 increases the workpiece's conveying speed to convey the workpiece at high speed. Then, in step S20, the conveying device 20 conveys the workpiece to a predetermined position. Furthermore, the determination of the number of items removed in step S14 and the determination of the holding state's good state in step S17 can be performed simultaneously.

[0056] Figure 7An example of an electrical circuit with four electrodes is shown. In this example, the robot arm 10 is equipped with four electrical characteristic measuring devices: the first electrical characteristic measuring device 16 measures a first characteristic value between electrodes AD, the second electrical characteristic measuring device 16 measures a second characteristic value between electrodes DC, the third electrical characteristic measuring device 16 measures a third characteristic value between electrodes AC, the fourth electrical characteristic measuring device 16 measures a fourth characteristic value between electrodes AB, the fifth electrical characteristic measuring device 16 measures a fifth characteristic value between electrodes DB, and the sixth electrical characteristic measuring device 16 measures a sixth characteristic value between electrodes CB. Furthermore, it should be noted that... Figure 7 In the diagram, thick solid lines represent wires on the positive side, and thin solid lines represent wires on the negative side. The first to sixth characteristic values ​​are appropriately read and used by the control device 30 (determination unit 31). In such an electrical circuit structure, the more electrodes there are, the larger the number of electrical characteristic measuring devices becomes. Therefore, it is desirable for the robot arm 10 to be a structure capable of instantaneously switching contacts to any two electrodes so that electrical characteristic values ​​can be measured using a single electrical characteristic measuring device (e.g., a rotary contact described later).

[0057] Figure 8 An example of the structure of the rotary contact 40 with three electrodes 13 is shown. The rotary contact 40 has multiple terminals 40a, 40b with a predetermined center angle depending on the arrangement of the electrodes 13. For example, when three electrodes 13 are arranged at equal intervals along the circumference of the chuck 12, the rotary contact 40 may have two terminals 40a, 40b with a center angle of 120°. Furthermore, it should be noted that... Figure 8 In the diagram, the black arrow indicates terminal 40a on the positive side, and the gray arrow indicates terminal 40b on the negative side. The rotating contact 40 is configured such that its rotation angle is controlled, for example, by a drive source (not shown) such as a motor, and the contact is instantaneously switched to any two electrodes 13. Furthermore, the drive source can be controlled by the control device 30.

[0058] Figure 9 An example of the operation of the rotary contact 40 when there are three electrodes 13 is shown. For example, in the initial state, the rotary contact 40 is pre-positioned at a rotation angle that does not contact any of the electrodes 13. When the suction cup 12 attracts the workpiece, the contacts of the rotary contact 40 are switched between electrodes AB to measure the electrical characteristic value (first characteristic value), then the contacts of the rotary contact 40 are switched between electrodes BC to measure the electrical characteristic value (second characteristic value), and then the contacts of the rotary contact 40 are switched between electrodes CA to measure the electrical characteristic value (third characteristic value). Since the rotary contact 40 can switch the contacts to any two electrodes 13 in this way, even if the number of electrodes 13 increases, only one electrical characteristic measuring instrument 16 can be used to measure three characteristic values ​​(first characteristic value to third characteristic value). Furthermore, workpiece removal detection can be performed with fewer restrictions.

[0059] Figure 10 An example of the structure of the rotary contact 40 with four electrodes 13 is shown. For example, when four electrodes 13 are arranged at equal intervals along the circumference of the chuck 12, the rotary contact 40 may have two terminals 41a, 41b with a central angle of 90° and two terminals 42a, 42b with a central angle of 180°. Furthermore, it should be noted that... Figure 10 In the diagram, black arrows indicate terminals 41a and 41b on the positive side, and gray arrows indicate terminals 42a and 42b on the negative side. The rotating contact 40 is controlled by a drive source (not shown) such as a motor to rotate its angle, and instantaneously switches the contacts to any two electrodes 13. Furthermore, the drive source can be controlled by a control device 30.

[0060] Figure 11 An example of the operation of the rotating contact 40 is shown when there are four electrodes 13. For example, in the initial state, the rotating contact 40 is pre-positioned at a rotation angle that does not contact any of the electrodes 13. When the suction cup 12 attracts the workpiece, the contacts of the rotating contact 40 are switched to the area between electrodes BC to measure the electrical characteristic value (sixth characteristic value). Then, the contacts of the rotating contact 40 are switched to the area between electrodes BD to measure the electrical characteristic value (fifth characteristic value). Next, the contacts of the rotating contact 40 are switched to the area between electrodes CD to measure the electrical characteristic value (second characteristic value). Then, the contacts of the rotating contact 40 are switched to the area between electrodes CA to measure the electrical characteristic value (third characteristic value). Next, the contacts of the rotating contact 40 are switched to the area between electrodes DA to measure the electrical characteristic value (first characteristic value). Next, the contacts of the rotating contact 40 are switched to the area between electrodes BD to measure the electrical characteristic value (fifth characteristic value). Then, the contacts of the rotating contact 40 are switched to the area between electrodes AB to measure the electrical characteristic value (fourth characteristic value). Finally, the contacts of the rotating contact 40 are switched to the area between electrodes AC to measure the electrical characteristic value (third characteristic value). Furthermore, in this example, the fifth and third characteristic values ​​are repeatedly measured, but the rotation angle of the rotary contact 40 can be controlled in a non-repetitive manner. Since the rotary contact 40 can switch the contact point to any two electrodes 13 in this way, even if the number of electrodes 13 increases, six characteristic values ​​(the first to sixth characteristic values) can be measured using only one electrical characteristic measuring instrument 16. Therefore, workpiece removal detection can be implemented with fewer restrictions.

[0061] According to the above embodiment, the robot arm 10 has at least three electrodes 13, thereby enabling the detection of the workpiece's holding state. Furthermore, by measuring the electrical characteristics of the electrical circuit formed through the contact of any two electrodes 13 with the workpiece, the number of workpieces removed can also be detected. Since workpiece removal is detected by measuring electrical characteristics, the workpiece is not limited to a magnetic material; it can be any conductive material. Moreover, workpiece removal detection can be performed even when the workpieces are pressed together in a state where their shapes are identical. Therefore, workpiece removal detection (detection of the number of removals, detection of the holding state, etc.) can be implemented with fewer limitations.

[0062] Furthermore, the electrode 13 protrudes from the suction cup 12, thus enabling the removal and detection of workpieces even with a Bernoulli-style manipulator that holds the workpiece in a non-contact manner. Additionally, even for workpieces with poor fit, such as those with wrinkles or unevenness, the electrode 13 can float according to the shape of the workpiece, allowing for removal and detection with minimal restrictions.

[0063] Furthermore, since the rotating contact 40 can switch the contact point to any two electrodes 13, even if the number of electrodes 13 increases, the electrical characteristic value between any two electrodes can be measured using only one electrical characteristic measuring instrument 16. Consequently, workpiece removal detection can be performed with fewer restrictions.

[0064] Furthermore, the program executed by the aforementioned processor, and the program for executing the aforementioned flowchart, can be provided either by recording on a computer-readable non-transitory recording medium, such as a CD-ROM, or by distributing and providing it via wired or wireless means from a server device on a WAN (wide area network) or LAN (local area network).

[0065] Various embodiments have been described in this specification, but it is to be understood that the invention is not limited to the embodiments described above, and various modifications can be made within the scope of the claims.

[0066] Explanation of reference numerals in the attached figures

[0067] 1: Robotic arm system; 10: Robotic arm; 11: Palm; 12: Suction cup; 12a: Nozzle; 12b: Nozzle orifice; 12c: Suction surface; 13: Electrode; 13a: Electrode cylinder; 13b: Spring; 13c: Locking component; 14: Wire; 15: Position offset suppression pad; 15a: Surface; 16: Electrical characteristic measuring device; 17: Fluid adjustment device; 20: Conveying device; 30: Control device; 31: Judgment unit; 32: Conveying control unit; 40: Rotary contact; 40a, 40b: Terminal; 41a, 41b: Terminal; 42a, 42b: Terminal; 50: Loading device; W: Workpiece.

Claims

1. A robot system comprising: a chuck that attracts an electroconductive workpiece using a fluid effect; at least three electrodes provided to the chuck; an electrical property measurer that measures an electrical property of an electrical circuit formed by contact of any two of the electrodes with the workpiece; and a determiner that determines whether a holding state of the workpiece is good based on a combination of the electrical properties, wherein the at least three electrodes are arranged at equal intervals in a circumferential direction of the chuck.

2. A robot system comprising: a chuck that attracts an electroconductive workpiece using a fluid effect; at least three electrodes provided to the chuck; an electrical property measurer that measures an electrical property of an electrical circuit formed by contact of any two of the electrodes with the workpiece; and a determiner that determines both a number of the workpieces taken out and whether a holding state of the workpiece is good based on the electrical property, wherein the at least three electrodes are arranged at equal intervals in a circumferential direction of the chuck.

3. The robot system according to claim 2, further comprising a fluid adjuster that adjusts a flow pressure or a flow rate of the fluid according to the number of the workpieces taken out.

4. The robot system according to claim 3, wherein the fluid adjuster repeatedly performs the adjustment of the flow pressure or the flow rate until the workpiece is one.

5. The robot system according to claim 1 or 2, further comprising a conveyer that adjusts a conveyance speed of the workpiece according to whether the holding state of the workpiece is good. wherein 6. The robot system according to claim 1 or 2, wherein the workpiece is a gas-permeable workpiece, and the chuck is a non-contact chuck provided with a nozzle for ejecting the fluid.

7. A robot comprising: a chuck that attracts an electroconductive workpiece using a fluid effect; at least three electrodes provided to the chuck; and a rotary contact that can switch a contact point to any two of the electrodes, wherein the at least three electrodes are arranged at equal intervals in a circumferential direction of the chuck, and the rotary contact is provided with a plurality of terminals having a prescribed central angle according to the arrangement of the electrodes.

8. The robot according to claim 7, wherein the workpiece is a gas-permeable workpiece, and the chuck is a non-contact chuck provided with a nozzle for ejecting the fluid. ​ ​ ​ wherein, ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ wherein ​ ​ ​

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