Actuator system

Abstract

This technology provides a way to miniaturize actuators while suppressing increases in cycle time. [Solution] The actuator system comprises an actuator having a shaft, a drive unit for moving the shaft axially, a first sensor for detecting that the tip of the shaft is in contact with a workpiece, and a first control unit; and a pneumatic unit having a switching unit for switching the supply and stopping of negative pressure to the hollow portion of the shaft, a second sensor for detecting that a workpiece is attracted to the tip of the shaft, and a second control unit. The first control unit of the actuator acquires the sensing result of the second sensor by communicating with the second control unit of the pneumatic unit via serial communication. The first control unit of the actuator also controls the switching unit by communicating with the second control unit of the pneumatic unit via serial communication.

Description

Technical Field

[0001] The present invention relates to an actuator system.

Background Art

[0002] As an actuator for picking up and placing a workpiece, there is known one that makes the tip of a hollow shaft contact the workpiece by axially displacing the hollow shaft, and sucks the workpiece to the tip of the shaft by applying negative pressure inside the shaft (see, for example, Patent Document 1).

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0004] In an actuator as in the above prior art, it is conceivable to miniaturize the actuator by configuring pneumatic components including a device for switching the pressure at the tip of the shaft and a device for detecting the pressure at the tip of the shaft as a separate body independent of the actuator.

[0005] When the pneumatic components are configured as a separate body independent of the actuator, the actuator and the pneumatic components are connected to an external control device (for example, a PLC (Programmable Logic Controller), etc.) One might consider configuring the system to be controlled by a pneumatic component. However, in such a configuration, the sensing results of the pneumatic component are transmitted from the pneumatic component to an external control device, the external control device calculates the control value of the actuator according to the sensing results received from the pneumatic component, the calculated control value is transmitted from the external control device to the actuator, and the actuator acts on the shaft according to the control value received from the external control device. Thus, when an external control device is interposed between the actuator and the pneumatic component, the time lag between the sensing results of the pneumatic system and the operation of the actuator becomes large. As a result, the cycle time when workpiece pickup and / or placement are performed may become longer.

[0006] This invention has been made in view of the various problems described above, and its purpose is to provide a technology that can miniaturize actuators while suppressing an increase in cycle time. [Means for solving the problem]

[0007] The actuator system according to the present invention is An actuator comprising a shaft having a hollow portion at its tip, a drive unit for moving the shaft axially, a first sensor for detecting that the tip of the shaft is in contact with a workpiece, and a first control unit, A pneumatic unit having a switching unit for switching between supplying and stopping negative pressure to the hollow portion of the shaft, a second sensor provided in the passage through which air drawn out from the hollow portion flows when negative pressure is supplied to the hollow portion of the shaft, for detecting that a workpiece is adsorbed to the tip of the shaft, and a second control unit, Equipped with, The first control unit, To obtain the sensing results of the first sensor, Controlling the aforementioned drive unit, By communicating with the second control unit via serial communication, the sensing results of the second sensor are acquired, and The switching unit is controlled by communicating with the second control unit via serial communication. It is configured to execute. [Effects of the Invention]

[0008] According to the present invention, it is possible to provide a technology that enables miniaturization of the actuator while suppressing an increase in cycle time. [Brief explanation of the drawing]

[0009] [Figure 1] This figure shows a schematic configuration of an example of a system to which the present invention is applied. [Figure 2] This figure shows an example of the actuator configuration in the embodiment. [Figure 3] This figure shows an example of the configuration of a pneumatic unit in an embodiment. [Figure 4] This is a schematic block diagram showing an example of the configuration of the controller, head circuit, and control circuit in the embodiment. [Figure 5] This figure illustrates an example of the operation of an FF circuit in a pneumatic unit according to an embodiment. [Figure 6] This is a sequence diagram showing the flow of data transmitted and received between each component of the system, and the processing flow performed by each component, when a workpiece pickup process is performed in the system according to the embodiment. [Figure 7] This sequence diagram shows the flow of data transmitted and received between the controller, actuator, and pneumatic unit, and the processing flow performed by each of these devices, when the actuator is restarted in the system of this embodiment. [Modes for carrying out the invention]

[0010] The actuator system according to the present invention comprises an actuator and a pneumatic unit. The actuator includes a shaft having a hollow portion at its tip, a drive unit for moving the shaft axially, a first sensor for detecting that the tip of the shaft is in contact with a workpiece, and a first control unit. The pneumatic unit includes a switching unit for switching the supply and cessation of negative pressure to the hollow portion of the shaft of the actuator, a second sensor provided in the air passage through which air drawn out of the hollow portion flows when negative pressure is supplied to the hollow portion of the shaft of the actuator, for detecting that a workpiece is adsorbed to the tip of the shaft, and a second control unit. The first control unit is configured to acquire the sensing result of the first sensor, control the drive unit, acquire the sensing result of the second sensor by communicating with the second control unit via serial communication, and control the switching unit by communicating with the second control unit via serial communication.

[0011] According to the actuator system of the present invention, the actuator and the pneumatic unit can be configured as separate components, thereby enabling miniaturization of the actuator. Furthermore, the first control unit can acquire the sensing results of the first sensor and control the drive unit without the need for an external control device. In addition, the first control unit can acquire the sensing results of the second sensor and control the switching unit without the need for an external control device. Therefore, when the actuator and the pneumatic unit are configured as separate components, it is possible to suppress the increase in the time lag between the sensing results of the first sensor and / or the second sensor being reflected in the operation of the drive unit and / or the switching unit.

[0012] In the actuator system according to the present invention, when a workpiece pickup request occurs... When this happens, the first control unit may be configured to perform the following processes. (1) Control the drive unit to move the shaft downward in the axial direction. (2) Determine whether the tip of the shaft has contacted the workpiece based on the sensing result of the first sensor (3) Control the drive unit to stop the downward movement of the shaft in the axial direction in response to the determination that the tip of the shaft has contacted the workpiece (4) Transmit a command for supplying negative pressure to the hollow portion of the shaft to the second control unit through serial communication (5) Receive the sensing result of the second sensor from the second control unit through serial communication (6) Determine whether the workpiece is adsorbed to the tip of the shaft according to the sensing result of the second sensor (7) Control the drive unit to move the shaft upward in the axial direction in response to the determination that the workpiece is adsorbed to the tip of the shaft

[0013] When the first control unit is configured as described above, even if the actuator and the pneumatic unit are configured separately, an increase in the tact time when picking up the workpiece can be suppressed.

[0014] The actuator system according to the present invention may further include a power switch that switches on and off the power supply to the actuator. Thereby, it is possible to turn off only the power supply to the actuator without turning off the power supply to the pneumatic unit. As an example, when it is necessary to stop the actuator during the picking up of the workpiece, by switching the power switch from on to off, it is possible to turn off only the power supply to the actuator. Thereby, even if the power supply to the actuator is turned off while the workpiece is adsorbed to the tip of the shaft, the supply of negative pressure from the pneumatic unit to the hollow portion of the shaft can be continued. Therefore, even if the power supply to the actuator is turned off, it is possible to prevent the workpiece from falling from the tip of the shaft.

[0015] In the actuator system according to the present invention, the first control unit may be configured to send a reset signal to the second control unit in response to the power switch being switched from off to on. The reset signal here may, in one example, be a signal to restart the second control unit.

[0016] However, while the second control unit is being reset, the control signal from the second control unit to the switching unit is interrupted, which may cause the switching unit to stop supplying negative pressure to the hollow part of the shaft. In other words, if it becomes necessary to stop the actuator while workpiece pickup is in progress, the power supply to the actuator will be temporarily stopped, and then when the power supply to the actuator is resumed, a reset signal will be sent from the first control unit to the second control unit. At that time, if the workpiece is attached to the tip of the shaft, the interruption of the control signal from the second control unit to the switching unit may cause the switching unit to stop supplying negative pressure to the hollow part of the shaft, potentially causing the workpiece to fall from the tip of the shaft.

[0017] In contrast, in the actuator system according to the present invention, the pneumatic unit may be equipped with a maintenance unit for maintaining the state of the switching unit when the second control unit is reset, in the state it was in before the second control unit was reset. This makes it possible for the switching unit to continue supplying negative pressure to the hollow part of the shaft even if a reset signal is transmitted from the first control unit to the second control unit while a workpiece is attached to the tip of the shaft. As a result, the workpiece that is held in place by suction at the tip of the shaft is prevented from falling. The retention unit may, in one example, be configured to include a flip-flop circuit.

[0018] Furthermore, in a configuration where the second control unit includes the maintenance unit described above, if the second control unit is reset, the first control unit may not be able to ascertain the state of the switching unit. Therefore, in the actuator system according to the present invention, the second control unit may be further configured to transmit a status signal including information indicating the state of the switching unit to the first control unit in response to receiving a reset signal transmitted from the first control unit. This allows the first control unit to ascertain the state of the switching unit.

[0019] The following describes specific embodiments of the present invention with reference to the drawings. Unless otherwise specified, the dimensions, materials, shapes, relative arrangements, etc., of the components described in these embodiments are not intended to limit the technical scope of the invention to those specific components.

[0020] <Embodiment> (System Overview) Figure 1 is a schematic diagram showing an example of a system S1 to which the present invention is applied. In Figure 1, system S1 includes an actuator 1 for picking up and placing a workpiece W, a pneumatic unit 2 that supplies negative pressure for attracting the workpiece W and positive pressure for detaching the workpiece W to the actuator 1, a controller 3 for controlling the actuator 1, a power supply 4 for supplying power to the actuator 1, the pneumatic unit 2, and the controller 3, and a PLC 7 for controlling the controller 3. System S1 may also include a moving device for moving the actuator 1 between a predetermined pickup position and a predetermined place position.

[0021] In the system S1 of this embodiment, when the operator starts the controller 3, the controller 3 supplies power from the power supply 4 to the actuator 1, thereby starting the actuator 1. Power supply to the pneumatic unit 2 may be performed manually or by the PLC 7.

[0022] With actuator 1, pneumatic unit 2, and controller 3 running, when a pickup request signal for workpiece W is sent from PLC 7 to controller 3, controller 3 sends the pickup program stored in controller 3 to actuator 1. Upon receiving the pickup program sent from controller 3, actuator 1 executes the pickup program to perform the workpiece W pickup process. Once actuator 1 has finished performing the workpiece W pickup process, controller 3 sends a pickup completion signal to PLC 7.

[0023] When actuator 1 is picking up workpiece W, and a place request signal for workpiece W is sent from PLC 7 to controller 3, controller 3 sends the place program held in controller 3 to actuator 1. Upon receiving the place program sent from controller 3, actuator 1 executes the place program to perform the place processing of workpiece W. When actuator 1 has finished performing the place processing of workpiece W, controller 3 sends a place completion signal to PLC 7.

[0024] According to the system S1 of this embodiment, a workpiece W placed in a predetermined location can be transported to another location.

[0025] (Actuator 1) Figure 2 shows an example of the configuration of the actuator 1 in this embodiment. The actuator 1 has an outer housing 10. A lid is attached to the housing 10, but Figure 2 shows the state with the lid removed. A part of the shaft 11 is housed inside the housing 10. The tip 11A side of the shaft 11 is formed to be hollow. The material used for the shaft 11 and the housing 10 can be, for example, metal (e.g., aluminum), but resin or the like can also be used.

[0026] In the following explanation, an XYZ Cartesian coordinate system will be established, and the position of each component will be described while referring to this XYZ Cartesian coordinate system. The direction of the long side of the largest surface of the housing 10, which is the direction of the central axis CA1 of the shaft 11, will be defined as the Z-axis direction, the direction of the short side of the largest surface of the housing 10 will be defined as the X-axis direction, and the direction perpendicular to the largest surface of the housing 10 will be defined as the Y-axis direction. The Z-axis direction is also the vertical direction. In the following, the upper side in the Z-axis direction in Figure 2 will be defined as the upper side of the actuator 1, and the lower side in the Z-axis direction in Figure 2 will be defined as the lower side of the actuator 1. Also, the right side in the X-axis direction in Figure 2 will be defined as the right side of the actuator 1, and the left side in the X-axis direction in Figure 2 will be defined as the left side of the actuator 1. Furthermore, the front side in the Y-axis direction in Figure 2 will be defined as the front side of the actuator 1, and the back side in the Y-axis direction in Figure 2 will be defined as the back side of the actuator 1.

[0027] In the example shown in Figure 2, the housing 10 has an opening in one of its surfaces perpendicular to the Y-axis direction (the front surface in Figure 2), and this opening is closed by a cover when in use. Note that Figure 2 shows the shaft 11 in the uppermost position (upper limit) along the Z-axis.

[0028] The housing 10 houses a rotary motor 12 that rotates the shaft 11 around its central axis CA1, a linear motor 13 that moves the shaft 11 in a direction along its central axis CA1 (i.e., the Z-axis direction) relative to the housing 10, and a pressure supply unit 15 for generating positive or negative pressure on the shaft 11. A through hole 1011 is formed in the lower end surface 101 of the housing 10 in the Z-axis direction, allowing the pressure supply unit 15 to pass through in the Z-axis direction. The lower tip 11A of the shaft 11 in the Z-axis direction protrudes downward from the pressure supply unit 15 in the Z-axis direction. The shaft 11 moves in the Z-axis direction by the linear motor 13 and rotates around the central axis CA1 by the rotary motor 12.

[0029] The base end 11B of the shaft 11, which is the end opposite to the tip 11A (the upper end in the Z-axis direction), is housed in the housing 10 and connected to the output shaft 121 of the rotary motor 12. This rotary motor 12 rotatably supports the shaft 11. The central axis of the output shaft 121 of the rotary motor 12 coincides with the central axis CA1 of the shaft 11. In addition to the output shaft 121, the rotary motor 12 includes a stator 122, a rotor 123 that rotates inside the stator 122, and a rotary encoder 124 that detects the rotation angle of the output shaft 121. As the rotor 123 rotates relative to the stator 122, the output shaft 121 and the shaft 11 also rotate in conjunction with the stator 122. The stator 122 is fixed to the motor housing 1200.

[0030] The linear motor 13 has a stator 131 fixed to the housing 10 and a movable element 132 that moves in the Z-axis direction relative to the stator 131. The stator 131 is provided with multiple coils, and the movable element 132 is provided with multiple permanent magnets. The coils are arranged at a predetermined pitch in the Z-axis direction, and multiple sets of three coils, each consisting of U, V, and W phases, are provided. In this embodiment, a moving magnetic field that moves linearly is generated by passing a three-phase armature current through these U, V, and W phase coils, causing the movable element 132 to move linearly in the Z-axis direction relative to the stator 131. The linear motor 13 is provided with a linear encoder 138 that detects the relative position of the movable element 132 with respect to the stator 131. Alternatively, the stator 131 can be provided with permanent magnets, and the movable element 132 can be provided with multiple coils. Motor 13 is an example of a "drive unit" according to the present invention.

[0031] The movable element 132 of the linear motor 13 and the stator 122 of the rotary motor 12 are connected via a linear guide device 134. The linear guide device 134 is movable in conjunction with the movement of the movable element 132 of the linear motor 13. The linear guide device 134 has a rail 1341 fixed to the housing 10 and two slider blocks 1342 assembled to the rail 1341. The rail 1341 extends in the Z-axis direction, and the slider blocks 1342 are configured to move along the rail 1341 in the Z-axis direction. Hereinafter, the slider block 1342 located on the upper side in the Z-axis direction will be referred to as the upper slider block 13421, and the slider block 1342 located on the lower side in the Z-axis direction will be referred to as the lower slider block 13422. However, when the two slider blocks 1342 are not distinguished, they will simply be referred to as slider block 1342.

[0032] One end of the upper connecting member 1351 is connected to the upper end of the upper slider block 13421. The other end of the upper connecting member 1351 is connected to the upper end of the movable element 132 of the linear motor 13. One end of the lower connecting member 1352 is connected to the lower end of the lower slider block 13422. The other end of the lower connecting member 1352 is connected to the lower end of the movable element 132 of the linear motor 13. The slider block 1342 and the movable element 132 of the linear motor 13 are connected via the upper connecting member 1351 and the lower connecting member 1352, so that the slider block 1342 moves in conjunction with the movement of the movable element 132 of the linear motor 13.

[0033] One end of the upper arm 1361 is connected to the lower end of the upper slider block 13421. The other end of the upper arm 1361 is connected to the motor housing 1200. One end of the lower arm 1362 is connected to the upper end of the lower slider block 13422. The other end of the lower arm 1362 is connected to the motor housing 1200. In the following, when the upper arm 1361 and the lower arm 1362 are not distinguished, they will be collectively referred to as the connecting arm 136. The slider block 1342 and the stator 122 of the rotary motor 12 are connected via the connecting arm 136 and the motor housing 1200, so that the stator 122 of the rotary motor 12 moves along with the movement of the slider block 1342.

[0034] The connecting arm 136 has a square cross-section and is positioned in the X-axis direction. A strain gauge 137 is fixed to the upper surface of the connecting arm 136 facing upward in the Z-axis direction. Hereinafter, the strain gauge 137 fixed to the upper arm 1361 will be referred to as the upper strain gauge 1371, and the strain gauge 137 fixed to the lower arm 1362 will be referred to as the lower strain gauge 1372. However, when the upper strain gauge 1371 and the lower strain gauge 1372 are not distinguished, they will simply be referred to as strain gauge 137. In the example shown in Figure 2, two strain gauges 137 are provided on the upper surface of the connecting arm 136 facing upward in the Z-axis direction, but instead, they may be provided on the lower surface of the connecting arm 136 facing downward in the Z-axis direction. The strain gauge 137 in this embodiment is an example of the "first sensor" according to the present invention.

[0035] The actuator 1 further includes an air passage 160. The air passage 160 is a passage through which air flows to generate positive and negative pressure at the tip 11A of the shaft 11. That is, when picking up a workpiece W, negative pressure can be generated at the tip 11A of the shaft 11 by drawing air from inside the shaft 11 through the air passage 160. This causes the workpiece W to be attracted to the tip 11A of the shaft 11. Also, by sending air into the shaft 11 through the air passage 160, positive pressure can be generated at the tip 11A of the shaft 11. This causes the workpiece W, which was adsorbed to the tip 11A of the shaft 11, to quickly detach from the tip 11A. Note that other gases may be used, not just air, as long as positive and negative pressure can be generated at the tip 11A of the shaft 11.

[0036] The air passage 160 includes a first connector 161, a first tube 162, a second connector 163, a second tube 164, a third connector 165, a third tube 166, a fourth connector 167, and an external connector 168. One end of the first connector 161 is fixed to the through hole 1501 of the pressure supply unit 15, for example, by a screw structure. One end of the first tube 162 is connected to the other end of the first connector 161. The other end of the first tube 162 is connected to one end of the second connector 163. The second connector 163 is fixed to the lower end surface of the lower connecting member 1352.

[0037] Furthermore, one end of the second tube 164 is connected to the other end of the second connector 163. The other end of the second tube 164 is connected to one end of the third connector 165. The second tube 164 is an elastically deformable tube. The second tube 164 may be formed from, for example, a synthetic resin.

[0038] The third connector 165 is fixed to the housing 10. One end of the third tube 166 is connected to the other end of the third connector 165. The third tube 166 is provided adjacent to the linear motor 13, parallel to the movable element 132 of the linear motor 13. The third tube 166 is positioned on the opposite side from the shaft 11 when viewed from the linear motor 13. The other end of the third tube 166 is connected to one end of the fourth connector 167. The other end of the fourth connector 167 is connected to an external connector 168 provided on the upper end surface 102 of the housing 10 in the Z-axis direction. The external connector 168 is configured to penetrate the upper end surface 102 of the housing 10 in the Z-axis direction. The external connector 168 is connected to the pneumatic unit 2 via an air hose or the like. An air vent connector 169 is provided next to the external connector 168. The air vent connector 169 penetrates the upper end surface 102 of the housing 10 in the Z-axis direction, and connects the inside and outside of the housing 10. A suction pump is connected to the air vent connector 169 via an air hose or the like, and the pump sucks air out of the housing 10 through the air vent connector 169, thereby cooling the inside of the housing 10.

[0039] Furthermore, the third tube 166 may be made of a metal with high thermal conductivity to facilitate heat dissipation from the stator 131 of the linear motor 13. This would allow the heat generated by the linear motor 13 to be more easily transferred to the air inside the third tube 166, increasing the amount of heat discharged to the outside along with the air. In addition, since the third tube 166 is positioned on the opposite side from the shaft 11 when viewed from the linear motor 13, it does not interfere with the operation of the components that move the shaft 11 in the Z-axis direction.

[0040] The upper end surface 102 of the housing 10 in the Z-axis direction is provided with a connector 141 for connecting a cable leading to the pneumatic unit 2 and a connector 142 for connecting a cable leading to the controller 3. In this embodiment, the cable connected to connector 141 is a CAN (Controller Area Network) standard cable between the actuator 1 and the pneumatic unit 2. It is configured to include communication lines for serial communication. In this embodiment, the cable connected to the connector 142 is configured to include communication lines for communication between the actuator 1 and the controller 3, and wires for supplying power from the power supply 4 to the actuator 1 via the controller 3.

[0041] The housing 10 of this embodiment houses the head circuit 17. Communication lines and electric wires drawn into the housing 10 from connectors 141 and 142 are connected to the head circuit 17. Furthermore, a rotary motor 12, a linear motor 13, a rotary encoder 124, a strain gauge 137, and a linear encoder 138 are electrically connected to the head circuit 17. As a result, the head circuit 17 can electrically control the rotary motor 12 and the linear motor 13 according to the sensing results of the rotary encoder 124, the strain gauge 137, and the linear encoder 138. The linear motor 13 is connected to the head circuit 17 via a flexible cable 1701. One end of the flexible cable 1701 is fixed to the head circuit 17, and the other end is fixed to the upper slider block 13421. The head circuit 17 in this embodiment is an example of the "first control unit" according to the present invention.

[0042] The pressure supply unit 15 has a cylindrical section 151 and two collars 152. The upper end of the cylindrical section 151 is formed in a flange shape and is fixed to the lower end of the motor housing 1200. A through hole 1511 is formed in the cylindrical section 151 through which the shaft 11 is inserted. The through hole 1511 is formed to penetrate the cylindrical section 151 in the Z-axis direction. The diameter of the through hole 1511 is larger than the outer diameter of the shaft 11. Therefore, a gap is formed between the inner surface of the through hole 1511 and the outer surface of the shaft 11. Enlarged diameter sections 1512 are provided at both ends of the through hole 1511, with the diameter of the hole being enlarged. The collars 152 are fitted into the two enlarged diameter sections 1512, respectively. The collars 152 are formed in a cylindrical shape, and the inner diameter of the collars 152 is slightly larger than the outer diameter of the shaft 11. In the following, the upper collar 152 in the Z-axis direction will be referred to as the first collar 1521, and the lower collar 152 in the Z-axis direction will be referred to as the second collar 1522. However, when the first collar 1521 and the second collar 1522 are not distinguished, they will simply be referred to as collar 152. The material of the collar 152 can be, for example, metal or resin. The inner diameter of the collar 152 and the outer diameter of the shaft 11 are adjusted so that the shaft 11 can rotate around the central axis CA1 inside the collar 152. In addition, the gap between the collar 152 and the shaft 11 is formed so that air flow is suppressed as much as possible. For this reason, the shaft 11, the through hole 1511, and the collar 152 are formed such that the gap between the inner surface of the collar 152 and the outer surface of the shaft 11 is smaller than the gap between the inner surface of the through hole 1511 near the center of the cylindrical portion 151 and the outer surface of the shaft 11.

[0043] As described above, a gap is provided between the inner surface of the through hole 1511 and the outer surface of the shaft 11. As a result, an internal space 1500 is formed inside the cylindrical portion 151, which is enclosed by the inner surface of the through hole 1511, the outer surface of the shaft 11, the lower end surface of the first collar 1521, and the upper end surface of the second collar 1522. In addition, a through hole 1501 is formed in the pressure supply portion 15, which connects the first connector 161 and the internal space 1500 and serves as an air passage.

[0044] A hollow section 111 is formed at the tip 11A of the shaft 11, such that the shaft 11 is hollow. One end of the hollow section 111 is formed to open at the tip 11A. A communication hole 112 is formed at the other end of the hollow section 111, connecting the internal space 1500 and the hollow section 111 in the X-axis direction. Therefore, the tip 11A of the shaft 11 and the first connector 161 are connected via the hollow section 111, the communication hole 112, the internal space 1500, and the through hole 1501. The communication hole 112 may also be formed in the Y-axis direction in addition to the X-axis direction.

[0045] With this configuration, when the linear motor 13 is driven to move the shaft 11 in the Z-axis direction, the pressure supply unit 15 also moves along with it, so that the communication hole 112 can always connect the internal space 1500 and the hollow section 111. Also, when the rotary motor 12 is driven to rotate the shaft 11 around the central axis CA1, the communication hole 112 can always connect the internal space 1500 and the hollow section 111, regardless of the angle of rotation of the shaft 11 around the central axis CA1. Therefore, no matter what state the shaft 11 is in, the communication between the hollow section 111 and the internal space 1500 is maintained, so that the hollow section 111 is always connected to the first connector 161.

[0046] Furthermore, regardless of the position of the shaft 11, when the pneumatic unit 2 draws in air through the external connector 168, air in the hollow section 111 is drawn in through the air passage 160, the through hole 1501, the internal space 1500, and the communication hole 112. As a result, the shaft 1 A negative pressure can be generated in the hollow portion 111 of the shaft 11. That is, a negative pressure can be generated at the tip portion 11A of the shaft 11. This allows the workpiece W to be attracted to the tip portion 11A of the shaft 11.

[0047] As mentioned above, a gap is also formed between the inner surface of the collar 152 and the outer surface of the shaft 11. However, this gap is smaller than the gap that forms the internal space 1500 (i.e., the gap formed between the inner surface of the through hole 1511 and the outer surface of the shaft 11). Therefore, even if air in the internal space 1500 is drawn in from the air passage 160, the flow of air between the inner surface of the collar 152 and the outer surface of the shaft 11 can be suppressed. This makes it possible to generate negative pressure at the tip 11A of the shaft 11, which is sufficient to pick up the workpiece W. In addition, regardless of the position of the shaft 11, supplying positive pressure to the external connector 168 can generate positive pressure in the hollow section 111. That is, positive pressure can be generated at the tip 11A of the shaft 11. This makes it possible to quickly detach the workpiece W that is adsorbed to the tip 11A of the shaft 11 from the tip 11A.

[0048] (Pneumatic unit 2) Figure 3 shows an example of the configuration of the pneumatic unit 2 in this embodiment. The pneumatic unit 2 in this embodiment is a unit for generating positive and negative pressure at the tip 11A (hollow portion 111) of the shaft 11 of the actuator 1, and is constructed separately from the actuator 1. The pneumatic unit 2 has an outer housing 20. A lid is attached to the housing 20, but Figure 3 shows it with the lid removed. The material of the housing 20 can be, for example, metal (e.g., aluminum), but resin or the like can also be used. In the description of the pneumatic unit 2, the vertical direction in Figure 3 is defined as the Z-axis direction, the left-right direction in Figure 3 is defined as the X-axis direction, and the depth direction in Figure 3 is defined as the Y-axis direction.

[0049] A block 28 is housed inside the housing 20. The block 28 is a solid component made of metal or resin. A negative pressure solenoid valve 24, a positive pressure solenoid valve 25, a pressure sensor 26, and a flow sensor 27 are fixed to the block 28.

[0050] A negative pressure passage 21 (dotted line in Figure 3) is formed in the block 28 and the negative pressure solenoid valve 24. The negative pressure passage 21 is composed of holes provided in the block 28 and the negative pressure solenoid valve 24. Note that the portion of the negative pressure passage 21 that is composed of holes in the block 28 may be composed of a tube instead of the holes.

[0051] A positive pressure passage 22 (dotted line in Figure 3) is formed in the block 28 and the positive pressure solenoid valve 25. The positive pressure passage 22 is composed of holes provided in the block 28 and the positive pressure solenoid valve 25. The portion of the positive pressure passage 22 that is composed of holes provided in the block 28 may be composed of a tube instead of the holes.

[0052] A common passage 23 (a dashed line in Figure 3) is formed between block 28 and the flow sensor 27. The common passage 23 is composed of holes provided in block 28 and the flow sensor 27. The portion of the common passage 23 that is composed of holes provided in block 28 may be composed of a tube instead of a hole. One end of a branch passage 23a is connected to the common passage 23. The other end of the branch passage 23a is connected to (communicates with) the pressure sensor 26. The branch passage 23a may be composed of a hole provided in block 28, or it may be composed of a tube.

[0053] One end of the negative pressure passage 21 is configured to communicate with a negative pressure connector 211. The negative pressure connector 211 penetrates the upper end surface 201 in the Z-axis direction of the housing 20, and an air hose connected to an external pump for drawing in air is connected to it. The other end of the negative pressure passage 21 is shared It is configured to communicate with one end of passage 23.

[0054] One end of the positive pressure passage 22 is configured to communicate with a positive pressure connector 221. The positive pressure connector 221 penetrates the upper end surface 201 of the housing 20 in the Z-axis direction, and an air hose connected to an external pump for discharging air is connected to it. The other end of the positive pressure passage 22 is configured to communicate with the connection between the other end of the negative pressure passage 21 and one end of the common passage 23. That is, the other ends of the negative pressure passage 21 and the positive pressure passage 22 merge and communicate with one end of the common passage 23.

[0055] The other end of the shared passageway 23 is configured to be connected to an external connector 232 via a connector 231. The external connector 232 penetrates the upper end surface 201 of the housing 20 in the Z-axis direction and is connected to an external connector 168 of the actuator 1 via an air hose or the like.

[0056] The negative pressure solenoid valve 24 is configured to switch between continuity and blockage of the negative pressure passage 21 by opening and closing a valve mechanism located in the middle of the negative pressure passage 21. The positive pressure solenoid valve 25 is configured to switch between continuity and blockage of the positive pressure passage 22 by opening and closing a valve mechanism located in the middle of the positive pressure passage 22. The negative pressure solenoid valve 24 and the positive pressure solenoid valve 25 in this embodiment are examples of the "switching unit" according to the present invention.

[0057] The pressure sensor 26 is configured to sense the pressure in the branch passage 23a. Since the branch passage 23a is connected to the common passage 23, the pressure sensed by the pressure sensor 26 can also be said to be the pressure in the common passage 23. Furthermore, in this embodiment, since the common passage 23 is connected to the hollow portion 111 of the shaft 11 of the actuator 1 via the connector 231, the external connector 232, and the air hose, the pressure sensed by the pressure sensor 26 can also be said to be the pressure in the hollow portion 111.

[0058] The flow sensor 27 is configured to sense the flow rate of air flowing through the shared passage 23. In this embodiment, since the shared passage 23 is connected to the hollow portion 111 of the shaft 11 of the actuator 1 via the connector 231, the external connector 232, and the air hose, the flow rate sensed by the flow sensor 27 can also be described as the flow rate of air flowing through the hollow portion 111.

[0059] The pressure sensor 26 and flow sensor 27 in this embodiment are examples of the "second sensor" according to the present invention. Note that only one of the pressure sensor 26 and flow sensor 27 may be placed in the common passage 23. In that case, the one sensor placed in the common passage 23 corresponds to the "second sensor" according to the present invention.

[0060] The upper end surface 201 of the housing 20 in the Z-axis direction is provided with a connector 271 for connecting a cable leading to the power supply 4 and a connector 272 for connecting a cable leading to the actuator 1. In this embodiment, the cable connected to connector 271 includes a wire for supplying power from the power supply 4 to the pneumatic unit 2. In this embodiment, the cable connected to connector 272 includes a communication line for performing CAN standard serial communication between the actuator 1 and the pneumatic unit 2.

[0061] In this embodiment, the housing 20 houses the control circuit 29. Communication lines and electric wires drawn into the housing 20 from connectors 271 and 272 are connected to the control circuit 29. Furthermore, a negative pressure solenoid valve 24, a positive pressure solenoid valve 25, a pressure sensor 26, and a flow sensor 27 are electrically connected to the control circuit 29. As a result, the control circuit 29 can acquire sensing results from the pressure sensor 26 and the flow sensor 27, and can control the negative pressure solenoid valve 24 and the positive pressure solenoid valve 25. Route 29 is an example of the "second control unit" according to the present invention.

[0062] (Block configuration of system S1) Figure 4 shows an example of the block configuration of system S1 in this embodiment. First, the block configuration of PLC7 will be described. In this embodiment, PLC7 is configured as a computer including a processor, main memory, and auxiliary memory. As shown in Figure 4, such PLC7 is configured to include a control unit 71, a storage unit 72, and a communication interface 73.

[0063] The control unit 71 implements various functions, as described later, by executing a dedicated program stored in the memory unit 72. As an example, the control unit 71 includes a hardware processor such as a CPU (Central Processing Unit) or DSP (Digital Signal Processor). The control unit 71 may further include RAM (Random Access Memory), ROM (Read Only Memory), and cache memory, etc.

[0064] The memory unit 72 is configured to include an auxiliary storage device and stores various types of information. The memory unit 72 may also be a memory area constructed within the auxiliary storage device. The information stored in the memory unit 72 includes the OS, dedicated programs related to the pickup and placement processes of the workpiece W, and data used by these programs.

[0065] The communication interface 73 includes a communication interface for connecting the PLC7 to a network. The network may be a LAN (Local Area Network) or a WAN (Wide Area Network). In this embodiment, the communication interface 73 is a network It communicates with the controller 3 through this interface. If the system S1 in this embodiment includes the aforementioned moving device (a device for moving the actuator 1 between a predetermined pickup position and a predetermined place position), the communication I / F 73 may be configured to communicate with the moving device as well through the network.

[0066] In the PLC7 configured as described above, when the actuator 1 is in a predetermined pickup position (for example, a position where the tip 11A of the shaft 11 of the actuator 1 is directly above the workpiece W), the control unit 71 transmits a pickup request signal to the controller 3 via the communication interface 73. Subsequently, when the communication interface 73 receives the pickup completion signal transmitted from the controller 3 (described later), the control unit 71 transmits a place request signal to the controller 3 via the communication interface while the actuator 1 is in a predetermined place position (for example, a position where the tip 11A of the shaft 11 of the actuator 1 is directly above the place where the workpiece W should be placed).

[0067] Next, the block configuration of controller 3 will be described. Controller 3 is configured as a computer including a processor, main memory, and auxiliary memory. As shown in Figure 4, such controller 3 is configured to include a control unit 31, a storage unit 32, a communication interface 33, an input / output unit 34, and a power switch 35.

[0068] The configuration of the control unit 31 and memory unit 32 of the controller 3 is the same as that of the control unit 71 and memory unit 72 of the PLC 7, so their explanation is omitted. However, the memory unit 32 of the controller 3 includes a program to be executed by the control unit 31 and the data used by that program, as well as a program to be executed by the actuator 1. The program to be executed by the actuator 1 includes a pickup program that defines the processing flow when picking up the workpiece W, and a placement program that defines the processing flow when placing the workpiece W.

[0069] The controller 3's communication interface 33 includes a communication interface for connecting the controller 3 to a network, and a communication interface for connecting the controller 3 to the actuator 1 via serial communication. In this embodiment, the communication interface 33 communicates with the PLC 7 via the network and with the actuator 1 via serial communication. In this embodiment, the communication interface 33 is configured to communicate with the actuator 1 via serial communication conforming to the RS-485 standard.

[0070] The input / output unit 34 accepts input operations performed by the operator while simultaneously presenting information to the user. The input / output unit 34 may, in one example, include a keyboard, mouse, and display.

[0071] The power switch 35 is a switch circuit for switching the power supply from the power source 4 to the actuator 1 on and off. The power switch 35 in this embodiment is an example of a "power switch" according to the present invention.

[0072] In the controller 3 configured as described above, when the communication interface 33 receives a pickup request signal transmitted from the PLC 7, the control unit 31 transmits the pickup program stored in the memory unit 32 to the actuator 1 via the communication interface 33. Subsequently, when the communication interface 33 receives the pickup completion notification transmitted from the actuator 1 (described later), the control unit 31 transmits a pickup completion signal, which indicates that the workpiece W pickup process by the actuator 1 has been completed, to the PLC 7 via the communication interface.

[0073] Furthermore, in the controller 3 configured as described above, when the communication interface 33 receives a place request signal transmitted from the PLC 7, the control unit 31 transmits the place program stored in the memory unit 32 to the actuator 1 via the communication interface 33. Subsequently, when the communication interface 33 receives the place completion notification transmitted from the actuator 1 (described later), the control unit 31 transmits a place completion signal, which indicates that the actuator 1 has completed the place processing of the workpiece W, to the PLC 7 via the communication interface.

[0074] Next, the block configuration of actuator 1 will be described. As shown in Figure 4, actuator 1 in this embodiment is composed of a rotary motor 12, a linear motor 13, a rotary encoder 124, a strain gauge 137, a linear encoder 138, and a head circuit 17. The rotary motor 12, linear motor 13, rotary encoder 124, strain gauge 137, linear encoder 138, and head circuit 17 are electrically connected by a bus or the like.

[0075] The head circuit 17 is configured as a microcomputer including a processor, main memory, and auxiliary memory. As shown in Figure 4, such a head circuit 17 has a control unit 171, a storage unit 172, and a communication interface 173.

[0076] The control unit 171 implements various functions, as described later, by executing programs (pickup program, place program) provided by the controller 3. The control unit 171, like the control unit 31 of the controller 3 and the control unit 71 of the PLC 7, is composed of a hardware processor such as a CPU or DSP, RAM, ROM, and cache memory.

[0077] The memory unit 172 is configured to include an auxiliary storage device and stores various types of information. The information stored in the memory unit 172 includes data used by the control unit 171 when executing the pickup program and the placement program.

[0078] The communication interface 173 is a communication interface for serial communication with the pneumatic unit 2 and the controller 3. In this embodiment, the communication interface 173 is configured to communicate with the controller 3 via RS-485 serial communication and with the pneumatic unit 2 via CAN serial communication.

[0079] In the head circuit 17 configured as described above, when the communication interface 173 receives the pickup program transmitted from the controller 3, the control unit 171 loads the program into the RAM's work area and executes it, thereby performing the pickup process of the workpiece W. When the pickup process of the workpiece W is completed, the control unit 171 sends a pickup completion notification, which indicates that the pickup process of the workpiece W has been completed, to the controller 3 via the communication interface 173. Details of the pickup process will be described later.

[0080] Furthermore, in the head circuit 17 configured as described above, when the communication interface 173 receives the placement program transmitted from the controller 3, the control unit 171 loads the program into the RAM's work area and executes it, and performs the placement process of the workpiece W through the execution of the program. When the placement process of the workpiece W is completed, the control unit 171 sends a placement completion notification, which is a notification indicating that the placement process of the workpiece W has been completed, to the controller 3 via the communication interface 173.

[0081] Furthermore, in the head circuit 17 configured as described above, the control unit 171 transmits a reset signal to the pneumatic unit 2 in response to the power supply from the power source 4 being switched from off to on. In one example, the reset signal may also be a signal to restart the control circuit 29 of the pneumatic unit 2. Such a reset signal is transmitted from the actuator 1 to the pneumatic unit 2 via a dedicated control signal line.

[0082] Next, the block configuration of the pneumatic unit 2 will be described. As shown in Figure 4, the pneumatic unit 2 of this embodiment is composed of a negative pressure solenoid valve 24, a positive pressure solenoid valve 25, a pressure sensor 26, a flow sensor 27, a control circuit 29, and an FF circuit 294. The pressure sensor 26, the flow sensor 27, the control circuit 29, and the FF circuit 294 are electrically connected by a bus or the like.

[0083] The control circuit 29 is configured as a microcomputer including a processor, main memory, and auxiliary memory. As shown in Figure 4, such a control circuit 29 has a control unit 291, a storage unit 292, and a communication interface 293.

[0084] The control unit 291 implements various functions, as described later, by executing programs stored in the memory unit 292. The control unit 291, like the control unit 171 of the head circuit 17, is configured to include a hardware processor such as a CPU or DSP, RAM, ROM, and cache memory.

[0085] The memory unit 292 is configured to include an auxiliary storage device and stores various types of information. The information stored in the memory unit 292 includes programs executed by the control unit 291, and data used when executing those programs.

[0086] Communication I / F293 is a communication interface for serial communication with actuator 1. In this embodiment, communication I / F293 is configured to communicate with actuator 1 via CAN standard serial communication.

[0087] Furthermore, the FF circuit 294 includes a negative pressure FF circuit 2941 positioned between the control unit 291 and the negative pressure solenoid valve 24, and a positive pressure FF circuit 2942 positioned between the control unit 291 and the positive pressure solenoid valve 25. In one example, the negative pressure FF circuit 2941 and the positive pressure FF circuit 2942 may be composed of D-type flip-flop circuits. In the following, if the negative pressure FF circuit 2941 and the positive pressure FF circuit 2942 are not distinguished, they will simply be referred to as FF circuit 294. Details of the FF circuit 294 will be described later.

[0088] In the pneumatic unit 2 configured as described above, the control unit 291 of the control circuit 29 acquires the sensing results of the pressure sensor 26 and the flow sensor 27 at a predetermined period (for example, several hundred microseconds to several milliseconds), and transmits the acquired sensing results to the actuator 1 via the communication I / F 293.

[0089] Furthermore, in the pneumatic unit 2 configured as described above, when the communication I / F 293 of the control circuit 29 receives a command transmitted from the actuator 1 (head circuit 17), the control unit 291 controls the negative pressure solenoid valve 24 and / or the positive pressure solenoid valve 25 in accordance with the command. For example, when the actuator 1 is performing a pickup process, if a command to open the negative pressure solenoid valve 24 is transmitted from the actuator 1 to the pneumatic unit 2, the control unit 291 sends a signal to open the negative pressure solenoid valve 24 via the negative pressure FF circuit 2941. Furthermore, when actuator 1 is performing a place process, if a command to close the negative pressure solenoid valve 24 and open the positive pressure solenoid valve 25 is transmitted from actuator 1 to the pneumatic unit 2, control unit 291 sends a signal to the negative pressure solenoid valve 24 via the negative pressure FF circuit 2941 to close the negative pressure solenoid valve 24, and sends a signal to the positive pressure solenoid valve 25 via the positive pressure FF circuit 2942 to open the positive pressure solenoid valve 25.

[0090] Here, the operation of the FF circuit 294 will be explained based on Figure 5. Figure 5 is a diagram illustrating an example of the operation of the FF circuit 294. The FF circuit 294 illustrated in Figure 5 is a D-type flip-flop circuit having an asynchronous clear terminal (CLR terminal), but any flip-flop circuit other than a D-type flip-flop circuit may be used as long as it can maintain the state immediately before the pneumatic unit 2 receives the reset signal. In this embodiment, the negative pressure solenoid valve 24 and the positive pressure solenoid valve 25 are configured such that when the signal value output from the output terminal (Q terminal) of the FF circuit 294 is "Low", the negative pressure solenoid valve 24 and the positive pressure solenoid valve 25 are closed, and when the signal value output from the Q terminal of the FF circuit 294 is "High", the negative pressure solenoid valve 24 and the positive pressure solenoid valve 25 are opened.

[0091] First, to open the negative pressure solenoid valve 24 (or positive pressure solenoid valve 25), as shown in (5-1) in Figure 5, the control unit 291 of the control circuit 29 inputs "Low" to the CLR terminal and "High" to the D terminal of the FF circuit 294. In this case, the FF circuit 294 reads the signal value ("High") input to the D terminal at the timing when the clock signal input to the CLK terminal rises from "Low" to "High", stores the read signal value ("High") within the FF circuit 294, and outputs it from the Q terminal. This opens the negative pressure solenoid valve 24 (or positive pressure solenoid valve 25). The signal value ("High") stored in the FF circuit 294 is held until the signal value input to the D terminal becomes "Low" at the timing when the CLK signal input to the CLK terminal rises from "Low" to "High". Alternatively, the signal value ("High") stored in the FF circuit 294 is held until the signal value input to the CLR terminal becomes "High".

[0092] Furthermore, when closing the negative pressure solenoid valve 24 (or positive pressure solenoid valve 25), as shown in (5-2) in Figure 5, the control unit 291 of the control circuit 29 inputs "Low" to the CLR terminal and "Low" to the D terminal of the FF circuit 294. In this case, the FF circuit 294 is closed at the timing when the CLK signal input to the CLK terminal rises from "Low" to "High". The signal value ("Low") input to the D terminal is read, and the read signal value ("High") is stored in the FF circuit 294 and output from the Q terminal. This closes the negative pressure solenoid valve 24 (or positive pressure solenoid valve 25). The signal value ("Low") stored in the FF circuit 294 is held until the signal input to the D terminal becomes "High" at the timing when the CLK signal input to the CLK terminal rises from "Low" to "High".

[0093] Furthermore, if the pneumatic unit 2's communication I / F 293 receives a reset signal transmitted from actuator 1, the control circuit 29 is restarted. During the restart of the control circuit 29, input from the control unit 291 to the CLR terminal and D terminal of the FF circuit 294 is stopped. In this case, the FF circuit 294 outputs the signal value it had stored immediately before the control circuit 29 was restarted from the Q terminal. Here, if the signal value stored in the FF circuit 294 immediately before the control circuit 29 was restarted was "High", the signal value output from the Q terminal of the FF circuit 294 during the restart of the control circuit 29 will be "High". As a result, even if the control circuit 29 is restarted while the negative pressure solenoid valve 24 or the positive pressure solenoid valve 25 is open, the open state of the negative pressure solenoid valve 24 or the positive pressure solenoid valve 25 can be maintained. Also, if the signal value stored in the FF circuit 294 immediately before the control circuit 29 was restarted was "Low", the signal value output from the Q terminal of the FF circuit 294 during the restart of the control circuit 29 will be "Low". As a result, even if the control circuit 29 is restarted while the negative pressure solenoid valve 24 or the positive pressure solenoid valve 25 is closed, the closed state of the negative pressure solenoid valve 24 or the positive pressure solenoid valve 25 can be maintained. In this embodiment, the "maintenance unit" according to the present invention is realized by the FF circuit 294 performing the operation shown in (5-3) in Figure 5.

[0094] (System operation) The operation of system S1 according to this embodiment will be described with reference to Figures 6 and 7. Figure 6 is a sequence diagram showing the flow of data transmitted and received between each component of system S1 and the processing flow performed by each component when workpiece W is picked up. Figure 7 is a sequence diagram showing the flow of data transmitted and received between controller 3, actuator 1, and pneumatic unit 2 and the processing flow performed by each of these devices when actuator 1 is restarted (power supply to actuator 1 is turned off and then turned on again).

[0095] When the workpiece W is to be picked up, as shown in Figure 6, the control unit 71 of the PLC 7 sends a pickup request signal to the controller 3 via the communication I / F 73, depending on the position of the actuator 1 at a predetermined pickup position (S101).

[0096] When a pickup request signal transmitted from PLC7 is received by the communication interface 33 of controller 3, the control unit 31 of controller 3 extracts the pickup program stored in the memory unit 32 and transmits the extracted pickup program to actuator 1 via the communication interface 33 (S102).

[0097] When the pickup program transmitted from the controller 3 is received by the communication I / F 173 of the actuator 1, the control unit 171 of the actuator 1 loads the pickup program into the RAM's work area and executes it to perform the pickup process of the workpiece W (S103-S112).

[0098] In the pickup process, first, the control unit 171 of the actuator 1 controls the linear motor 13 to start the downward movement (descent) of the shaft 11 in the Z-axis direction (S103). At this point, both the negative pressure solenoid valve 24 and the positive pressure solenoid valve 25 are assumed to be closed.

[0099] The control unit 171 of the actuator 1 determines whether the tip 11A of the shaft 11 has come into contact with the workpiece W (S104). The determination of whether or not the tip 11A of the shaft 11 has come into contact with the workpiece W is made based on the sensing result of the strain gauge 137. When the shaft 11 is descending downward in the Z-axis direction, if the tip 11A of the shaft 11 comes into contact with the workpiece W, the tip 11A is pressed against the workpiece W, and as a reaction, a load is applied from the workpiece W to the shaft 11. This load acts in a direction that generates strain on the connecting arm 136. In other words, when a load is applied from the workpiece W to the shaft 11, strain is generated in the connecting arm 136. The strain in the connecting arm 136 is detected by the strain gauge 137. The strain detected by the strain gauge 137 is correlated with the load that the shaft 11 receives from the workpiece W. Therefore, based on the sensing results of the strain gauge 137, the load acting from the workpiece W to the shaft 11 can be detected. When the load acting from the workpiece W to the shaft 11 exceeds a predetermined load, it can be determined that the tip 11A of the shaft 11 has come into contact with the workpiece W. The predetermined load is the threshold at which it is determined that the tip 11A of the shaft 11 has come into contact with the workpiece W. The predetermined load at that time may be set to a load that allows for more reliable pickup of the workpiece W while suppressing damage to the workpiece W. Furthermore, the predetermined load may be changed depending on the type of workpiece W.

[0100] If it is determined that the tip 11A of the shaft 11 has come into contact with the workpiece W, the control unit 171 of the actuator 1 controls the linear motor 13 to stop the downward movement of the shaft 11 in the Z-axis direction (S105).

[0101] When the downward descent of the shaft 11 in the Z-axis direction is stopped, the control unit 171 of the actuator 1 sends a command to the pneumatic unit 2 via the communication I / F 173 to open the negative pressure solenoid valve 24 (S106).

[0102] When a command transmitted from actuator 1 (a command to open the negative pressure solenoid valve 24) is received by the communication I / F 293 of the pneumatic unit 2, the control unit 291 of the pneumatic unit 2 sends a signal to open the negative pressure solenoid valve 24 to the negative pressure solenoid valve 24 via the negative pressure FF circuit 2941 (S107). In one example, as shown in (5-1) in Figure 5, the control unit 291 inputs "Low" to the CLR terminal of the negative pressure FF circuit 2941 and "High" to the D terminal of the negative pressure FF circuit 2941. In this case, the negative pressure FF circuit 2941 reads the signal value ("High") input to the D terminal at the timing when the CLK signal input to the CLK terminal rises from "Low" to "High", stores the read signal value ("High") in the negative pressure FF circuit 2941, and outputs it from the Q terminal. As a result, in the pneumatic unit 2, the negative pressure solenoid valve 24 opens and the positive pressure solenoid valve 25 closes. Consequently, the negative pressure passage 21 and the common passage 23 become electrically connected in the pneumatic unit 2, drawing air from the hollow portion 111 of the shaft 11 in the actuator 1 into the negative pressure passage 21 of the pneumatic unit 2, generating negative pressure at the hollow portion 111 (tip portion 11A) of the shaft 11. This creates a force at the tip portion 11A of the shaft 11 of the actuator 1 that attracts the workpiece W.

[0103] In this embodiment, since the head circuit 17 of the actuator 1 and the control circuit 29 of the pneumatic unit 2 are connected via CAN standard serial communication, the time lag from the moment it is determined that the tip 11A of the shaft 11 has come into contact with the workpiece W to the moment the negative pressure solenoid valve 24 begins to open can be shortened as much as possible.

[0104] The control unit 291 of the pneumatic unit 2 transmits the sensing results of the pressure sensor 26 and the flow rate sensor 27 to the actuator 1 via the communication I / F 293 (S108). In this embodiment, the sensing results of the pressure sensor 26 and the flow rate sensor 27 are transmitted to the actuator 1. The transmission is performed repeatedly at predetermined intervals. Such processing may be performed continuously, or only during a period specified by actuator 1 (for example, the execution period for pickup and place processing).

[0105] The control unit 171 of the actuator 1 determines whether the workpiece W is properly attracted to the tip 11A of the shaft 11, based on the sensing results transmitted from the pneumatic unit 2. For example, the control unit 171 may determine that the workpiece W is properly attracted to the tip 11A of the shaft 11, provided that the flow rate detected by the flow rate sensor 27 has decreased to a predetermined flow rate or less, and / or the pressure detected by the pressure sensor 26 has decreased to a predetermined pressure or less. The predetermined flow rate is the flow rate at which, if the flow rate detected by the flow rate sensor 27 has decreased to a predetermined flow rate or less, it can be determined that a negative pressure sufficient to properly attract the workpiece W is generated at the tip 11A of the shaft 11. The predetermined pressure is the pressure at which, if the pressure detected by the pressure sensor 26 is at or below the predetermined pressure, it can be determined that a negative pressure sufficient to properly attract the workpiece W is generated at the tip 11A of the shaft 11. If it is determined that the workpiece W is not properly attached to the tip 11A of the shaft 11 (S109), the determination process is repeatedly executed each time the communication I / F 173 receives the sensing result transmitted from the pneumatic unit 2.

[0106] When it is determined that the workpiece W is properly attracted to the tip 11A of the shaft 11 (S110), the control unit 171 of the actuator 1 controls the linear motor 13 to start moving (raising) the shaft 11 upward in the Z-axis direction (S111). In this case, the workpiece W, while still attracted to the tip 11A of the shaft 11, rises upward in the Z-axis direction along with the shaft 11. This completes the pickup of the workpiece W. At this time, the control unit 171 of the actuator 1 may also control the rotary motor 12 to rotate the shaft 11, thereby changing the orientation of the workpiece W that is attracted to the tip 11A of the shaft 11.

[0107] In this embodiment, since the head circuit 17 of the actuator 1 and the control circuit 29 of the pneumatic unit 2 are connected via CAN serial communication, the time lag from the point when the flow rate detected by the flow sensor 27 decreases to below a predetermined flow rate (when the pressure detected by the pressure sensor 26 decreases to below a predetermined pressure) to the point when the linear motor 13 begins to raise the shaft 11 upward in the Z-axis direction can be shortened as much as possible.

[0108] When the pickup of workpiece W is complete, the control unit 171 of actuator 1 sends a notification (pickup completion notification) indicating that the pickup of workpiece W is complete to controller 3 via communication I / F 173 (S112).

[0109] When the controller 3 receives the pickup completion notification transmitted from actuator 1 via the controller 3's communication interface 33, the controller 3's control unit 31 transmits a pickup completion signal to the PLC 7 via the communication interface 33 (S113).

[0110] When the PLC7's communication interface 73 receives the pickup completion signal transmitted from the controller 3, the PLC7's control unit 71 controls the aforementioned moving device to move the actuator 1 to a predetermined position. Once the actuator 1 has moved to the predetermined position, the workpiece W is placed.

[0111] When the workpiece W is to be placed, the control unit 71 of the PLC 7 should send a place signal to the controller 3 instead of a pickup request signal. In response, the control unit 31 of the controller 3 should send a place program to the actuator 1 instead of a pickup program. The control unit 171 of the actuator 1 moves the shaft 11 downwards in the Z-axis direction, and the workpiece W that is attracted to the tip 11A of the shaft 11 The workpiece W should be grounded. At that time, the control unit 171 of the actuator 1 should determine, based on the sensing result of the strain gauge 137, that the workpiece W, which is attached to the tip 11A of the shaft 11, has been grounded. The control unit 171 of the actuator 1 should then send a command to the pneumatic unit 2 via the communication I / F 173 to close the negative pressure solenoid valve 24 and open the positive pressure solenoid valve 25. The control unit 291 of the pneumatic unit 2 should send a signal to the negative pressure FF circuit 2941 to close the negative pressure solenoid valve 24 and a signal to the positive pressure FF circuit 2942 to open the positive pressure solenoid valve 25. The control unit 171 of the actuator 1 should also determine, based on the sensing result transmitted from the pneumatic unit 2, whether the workpiece W can be detached from the tip 11A of the shaft 11. Then, the control unit 171 of the actuator 1 determines that the workpiece W can be detached from the tip 11A of the shaft 11 and moves the shaft 11 upward in the Z-axis direction. Once the placement of the workpiece W is complete, the control unit 171 of the actuator 1 sends a placement completion notification to the controller 3, and in response, the control unit 31 of the controller 3 sends a placement completion signal to the PLC 7.

[0112] When the workpiece W is placed in the manner described above, the time lag from the moment it is determined that the workpiece W, which is attached to the tip 11A of the shaft 11, has made contact with the ground, to the moment when the negative pressure solenoid valve 24 begins to close and the positive pressure solenoid valve 25 begins to open can be shortened as much as possible. Furthermore, the time lag from the moment it is determined that the workpiece W, which is attached to the tip 11A of the shaft 11, can be detached, to the moment when the linear motor 13 begins to raise the shaft 11 upward in the Z-axis direction can be shortened as much as possible.

[0113] Here, it is conceivable that it may become necessary to emergency stop the actuator 1 while the workpiece W is being picked up or placed. In such a case, the operator can simply input an operation to turn off the power supply to the actuator 1 into the input / output unit 34 of the controller 3. When an operation to turn off the power supply to the actuator 1 is input into the input / output unit 34 of the controller 3, the control unit 31 of the controller 3 switches the power switch 35 from on to off. This stops the power supply from the power supply 4 to the actuator 1 via the controller 3. At that time, the power supply to the pneumatic unit 2 continues, so even if the workpiece W is attached to the tip 11A of the shaft 11, the open state of the negative pressure solenoid valve 24 can be maintained. As a result, it is possible to prevent the workpiece W attached to the tip 11A of the shaft 11 from falling.

[0114] If the actuator 1 is to be restarted after being stopped in an emergency as described above, the operator simply needs to input an operation to turn on the power supply to the actuator 1 into the input / output unit 34 of the controller 3. In that case, as shown in Figure 7, the control unit 31 of the controller 3 receives the operation from the operator through the input / output unit 34 (S301). The control unit 31 of the controller 3 then restarts the power supply from the power source 4 to the actuator 1 by switching the power switch 35 from off to on (S302).

[0115] When power supply from power source 4 to actuator 1 is resumed, the control unit 171 of actuator 1 executes a startup process (S303). The startup process may include, for example, a process to set the position of shaft 11 in the Z-axis direction to the uppermost position (upper limit), and a process to set the rotation angle of shaft 11 to a predetermined rotation angle. Note that the startup process is not limited to the example described above and can be changed depending on the embodiment. After completing the startup process described above, the control unit 171 of actuator 1 sends a reset signal to the pneumatic unit 2 via the communication I / F 173 (step S304).

[0116] A reset signal transmitted from actuator 1 is sent to the communication I / F293 of pneumatic unit 2. Therefore, upon receiving the signal, the control unit 291 of the pneumatic unit 2 executes a reset process for the pneumatic unit 2 (S305). During the reset process, the control circuit 29 is restarted.

[0117] During the execution of the reset process described above (while the control circuit 29 is restarting), the input of signals from the control unit 291 to the FF circuit 294 (signal input to the CLR terminal and the D terminal) is stopped. In this case, as shown in (5-3) in Figure 5 above, the FF circuit 294 outputs the signal value that it had stored in the FF circuit 294 immediately before the control circuit 29 was restarted from the Q terminal. That is, the signal value output from the Q terminal of the FF circuit 294 during the restart of the control circuit 29 is maintained at the same value as the signal value that was output from the Q terminal immediately before the control circuit 29 was restarted. As a result, the state of the negative pressure solenoid valve 24 and the positive pressure solenoid valve 25 during the reset process can be maintained at the same state as the state immediately before the reset process was executed. Therefore, even if the reset process of the pneumatic unit 2 is executed while the workpiece W is attached to the tip portion 11A of the shaft 11, the pneumatic unit 2 can continue to supply negative pressure to the hollow portion 111 of the shaft 11. In other words, even if the pneumatic unit 2 is reset while the workpiece W is attached to the tip 11A of the shaft 11, negative pressure can continue to be generated at the tip 11A of the shaft 11. As a result, even if the pneumatic unit 2 is reset while the workpiece W is attached to the tip 11A of the shaft 11, it is possible to prevent the workpiece W from falling from the tip 11A of the shaft 11.

[0118] Once the above-described reset process is completed (the control circuit 29 has restarted), the control unit 291 of the control circuit 29 determines the state of the negative pressure solenoid valve 24 and the positive pressure solenoid valve 25 by acquiring the signal values ​​output from the Q terminals of the negative pressure FF circuit 2941 and the positive pressure FF circuit 2942 (S306). Here, if the signal value output from the Q terminal of the negative pressure FF circuit 2941 is "Low", it is determined that the negative pressure solenoid valve 24 is in the closed state, and if the signal value output from the Q terminal of the negative pressure FF circuit 2941 is "High", it is determined that the negative pressure solenoid valve 24 is in the open state. Similarly, if the signal value output from the Q terminal of the positive pressure FF circuit 2942 is "Low", it is determined that the positive pressure solenoid valve 25 is in the closed state, and if the signal value output from the Q terminal of the positive pressure FF circuit 2942 is "High", it is determined that the positive pressure solenoid valve 25 is in the open state.

[0119] Once the control unit 291 of the pneumatic unit 2 has finished determining the status of the negative pressure solenoid valve 24 and the positive pressure solenoid valve 25, it transmits a status signal to the actuator 1 via the communication I / F 293 (S307). The status signal may, in one example, include information such as the status of the negative pressure solenoid valve 24, the status of the positive pressure solenoid valve 25, the sensing result of the pressure sensor 26, and the sensing result of the flow sensor 27.

[0120] When a status signal transmitted from the pneumatic unit 2 is received by the communication I / F 173 of the actuator 1, the control unit 171 of the actuator 1 transmits the status signal to the controller 3 via the communication I / F 173 (S308). The status signal at this time includes information indicating the state of the pneumatic unit 2 (state of the negative pressure solenoid valve 24, state of the positive pressure solenoid valve 25, sensing results of the pressure sensor 26, and sensing results of the flow sensor 27, etc.), as well as information indicating the state of the actuator 1 (position of the shaft 11 in the Z-axis direction, and rotation angle of the shaft 11, etc.). As a result, the controller 3 can understand the respective states of the actuator 1 and the pneumatic unit 2 at the time the actuator 1 is restarted. Consequently, the controller 3 can appropriately restart the pickup process or the place process.

[0121] (Effects of the configuration according to this embodiment) As explained above, in the system S1 of this embodiment, the actuator 1 and the pneumatic unit 2 are configured as separate components, allowing the actuator 1 to be miniaturized. Furthermore, In the system S1 of this embodiment, the head circuit 17 of the actuator 1 and the control circuit 29 of the pneumatic unit 2 are connected by CAN standard serial communication, so that various time lags, such as those exemplified in (T1)-(T4) below, can be shortened as much as possible. (T1) Time lag from the moment it is determined that the tip 11A of the shaft 11 has come into contact with the workpiece W during the pickup process until the moment the negative pressure solenoid valve 24 begins to open. (T2) Time lag in the pickup process from the point when the flow rate detected by the flow sensor 27 decreases to below a predetermined flow rate (the pressure detected by the pressure sensor 26 decreases to below a predetermined pressure) until the point when the linear motor 13 begins to raise the shaft 11 upwards in the Z-axis direction. (T3) Time lag in the placing process from the moment it is determined that the workpiece W, which is attached to the tip 11A of the shaft 11, has made contact with the ground, to the moment when the negative pressure solenoid valve 24 starts closing and the positive pressure solenoid valve 25 starts opening. (T4) Time lag in the placing process from the moment the pressure detected by the pressure sensor 26 returns to the positive pressure side until the moment the linear motor 13 begins to raise the shaft 11 upward in the Z-axis direction.

[0122] Furthermore, in system S1 of this embodiment, it is possible to switch only the power supply to actuator 1 on and off, among actuator 1 and pneumatic unit 2. Therefore, if it becomes necessary to stop the operation of actuator 1 in the middle of a pickup or placing process, the power supply to actuator 1 can be turned off while the power supply to pneumatic unit 2 remains on. As a result, even if the power supply to actuator 1 is turned off while the workpiece W is attached to the tip 11A of shaft 11, the supply of negative pressure from pneumatic unit 2 to the hollow portion 111 of shaft 11 can be continued. Consequently, it is possible to prevent the workpiece W attached to the tip 11A of shaft 11 from falling.

[0123] Furthermore, in system S1 of this embodiment, by incorporating the FF circuit 294 into the pneumatic unit 2, the state of the negative pressure solenoid valve 24 and the positive pressure solenoid valve 25 when the reset process of the control circuit 29 of the pneumatic unit 2 is executed can be maintained in the same state as the state immediately before the reset process was executed. As a result, even if the reset process of the control circuit 29 is executed while the workpiece W is attached to the tip 11A of the shaft 11, the supply of negative pressure from the pneumatic unit 2 to the hollow portion 111 of the shaft 11 can be continued, and negative pressure can be continuously generated at the tip 11A of the shaft 11. As a result, it is possible to prevent the workpiece W attached to the tip 11A of the shaft 11 from falling.

[0124] Furthermore, in the system S1 of this embodiment, when the reset process of the control circuit 29 of the pneumatic unit 2 is executed, a status signal including the state of the negative pressure solenoid valve 24 and the state of the positive pressure solenoid valve 25 is transmitted from the pneumatic unit 2 to the actuator 1. As a result, the actuator 1 can accurately grasp the state of the negative pressure solenoid valve 24 and the positive pressure solenoid valve 25 after the reset process has been executed.

[0125] Therefore, according to system S1 in this embodiment, it is possible to miniaturize the actuator 1 while suppressing an increase in cycle time in the pickup process and the place process. [Explanation of symbols]

[0126] 1...Actuator, 11...Shaft, 11A...Tip section, 111...Hollow section, 13...Linear motor, 137...Strain gauge, 17...Head circuit, 171...Control section, 172...Memory section, 173...Communication I / F, 2...Pneumatic unit, 21...Negative pressure passage, 22...Positive pressure passage, 23...Common passage, 23a...Branch passage 24...Solenoid valve for negative pressure, 25...Solenoid valve for positive pressure, 26...Pressure sensor, 27...Flow sensor, 29...Control circuit, 291...Control unit, 292...Memory unit, 293...Communication I / F, 294...FF circuit, 2941...FF circuit for negative pressure, 2942...FF circuit for positive pressure, 3...Controller, 31...Control unit, 35...Power switch, 4...Power supply, 7...PLC, W...Workpiece

Claims

1. An actuator having a shaft with a hollow portion at its tip, a drive unit for moving the shaft in the axial direction, a first sensor for detecting that the tip of the shaft is in contact with a workpiece, and a first control unit, A pneumatic unit having a switching unit for switching the supply and cessation of negative pressure to the hollow portion of the shaft, a second sensor provided in the passage through which air drawn out from the hollow portion flows when negative pressure is supplied to the hollow portion of the shaft, for detecting that the workpiece is adsorbed to the tip of the shaft, and a second control unit, Equipped with, The first control unit, To obtain the sensing results of the first sensor, Controlling the aforementioned drive unit, By communicating with the second control unit via serial communication, the sensing results of the second sensor are acquired, and The switching unit is controlled by communicating with the second control unit via serial communication. Configured to perform, Actuator system.

2. The first control unit, when a request to pick up the workpiece occurs, Controlling the drive unit to move the shaft downward in the axial direction, Based on the sensing result of the first sensor, it is determined whether the tip of the shaft has come into contact with the workpiece. In response to the determination that the tip of the shaft has come into contact with the workpiece, the drive unit is controlled to stop the downward axial movement of the shaft, A command to supply negative pressure to the hollow portion of the shaft is transmitted to the second control unit via serial communication, The sensing result of the second sensor is received from the second control unit via serial communication. In accordance with the sensing result of the second sensor, it is determined whether the workpiece is attached to the tip of the shaft, In response to the determination that the workpiece is attracted to the tip of the shaft, the drive unit is controlled to move the shaft axially upward, Execute The actuator system according to claim 1.

3. A power switch that switches the power supply to the actuator on and off. It also has, The actuator system according to claim 1 or 2.

4. The first control unit is configured to transmit a reset signal to the second control unit in response to the power switch being switched from off to on, The pneumatic unit includes a maintenance unit for maintaining the state of the switching unit when the second control unit is reset, the state it was in before the second control unit was reset. The actuator system according to claim 3.

5. The second control unit, upon receiving the reset signal, further transmits a status signal to the first control unit, which includes information indicating the state of the switching unit. Composed, The actuator system according to claim 4.

6. The maintenance unit is configured to include a flip-flop circuit. The actuator system according to claim 4.

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