Ceiling transporter

Abstract

This overhead conveying vehicle comprises a traveling unit that travels along a traveling rail; a hoisting unit provided on the traveling unit; a gripper unit that is hoisted by the hoisting unit and grasps items; an accelerometer provided on the gripper unit; and a control device that recognizes the hoisting operation state of the gripper unit and determines whether or not there is malfunction at the gripper unit on the basis of the hoisting operation state and the detection result of the accelerometer.

Description

Technical Field

[0001] The present disclosure relates to an overhead transporter.

Background Art

[0002] An overhead transporter that travels along a running rail and transports a container is known. The overhead transporter described in Patent Document 1 includes a traveling unit that travels along a running rail, a lifting unit provided on the traveling unit, and a holding unit that is lifted by the lifting unit and holds a flange portion of the container. The holding unit is provided with a center cone as a positioning portion that fits into a recess formed in the flange portion. The center cone is vertically movable with respect to the holding unit, and a relative upward movement of the center cone with respect to the holding unit is detected by a detection unit. The control unit recognizes that the holding unit has reached a height position at which a gripping operation should be performed based on the relative upward movement (or upward amount) of the center cone. The control unit stops the downward movement of the holding unit at that height position and causes the holding unit to execute a gripping operation.

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0004] Incidentally, for example, there is a possibility that the container is not placed at an appropriate position on the placement surface. As shown in Fig. 9(a), if the position of the container 90 is displaced with respect to the descending gripper unit (holding portion) 6, the center cone 8 may not fit into the recess 91a and may contact other parts of the flange portion 91 (see Fig. 9(b)). Even in such a case, a relative upward movement of the center cone 8 with respect to the gripper unit 6 may be detected, and there is a possibility that the gripping operation may be started (see Fig. 9(c)). In this case, the claw member 6a of the gripper unit 6 does not enter below the flange portion 91. Therefore, various errors may occur before the gripper unit 6 rises, but it is desirable to be able to detect such an abnormality in the gripper unit 6 before starting the gripping operation.

[0005] The present disclosure describes an overhead carrier that can reliably detect an abnormality such as at the start of a gripping operation in a gripper unit.

Means for Solving the Problems

[0006] An overhead carrier according to an aspect of the present disclosure includes a traveling unit that travels along a traveling rail, a lifting unit provided in the traveling unit, a gripper unit that is lifted by the lifting unit and grips an article, an accelerometer mounted on the gripper unit, and a control device that recognizes the lifting operation state of the gripper unit and determines the presence or absence of an abnormality in the gripper unit based on the lifting operation state and the detection result of the accelerometer.

[0007] According to this overhead carrier, the accelerometer detects an acceleration or the like generated in the gripper unit. The control device determines the presence or absence of an abnormality in the gripper unit based on the lifting operation state of the gripper unit and the detection result of the accelerometer. If only the detection result of the accelerometer is used, there is a possibility that an abnormality may be determined to have occurred even though the gripper unit is operating normally. However, by taking into account the lifting operation state of the gripper unit, the presence or absence of an abnormality in the gripper unit can be reliably detected.

[0008] The control device may determine whether there is an abnormality in the gripper unit based on whether the detected value of the accelerometer in the state where the gripper unit has stopped at the gripping position exceeds a preset first set value. In this case, it is possible to reliably detect whether there is a problem even if the gripping operation is started. For example, when the gripper unit attempts to grip an article, it is possible to prevent an excessive impact from being applied to the article.

[0009] The control device may determine whether there is an abnormality in the gripper unit based on whether the detected value of the accelerometer during the lifting and lowering operation of the gripper unit exceeds a preset second set value. In this case, it is possible to reliably detect whether there is a problem even if the lifting and lowering operation is continued. For example, when the gripper unit rises or falls, it is possible to prevent an excessive impact from being applied to the article.

[0010] The accelerometer may be capable of detecting at least the acceleration of the gripper unit in the vertical direction. In this case, it is possible to detect vertical shaking or impact in the gripper unit.

[0011] The accelerometer may be capable of detecting the acceleration of the gripper unit in a first horizontal direction and a second horizontal direction that are orthogonal to each other in the vertical direction and also orthogonal to each other. In this case, it is also possible to detect horizontal shaking or impact in the gripper unit. In the stopped state of the gripper unit, it is also possible to detect the inclination of the gripper unit.

Advantages of the Invention

[0012] According to the ceiling transporter of the present disclosure, it is possible to reliably detect an abnormality in the gripper unit.

Brief Description of the Drawings

[0013]

Figure 1

Figure 2

Figure 3

Figure 4

Figure 5

Figure 6

Figure 7

Figure 8

Figure 9

Embodiments for Carrying Out the Invention

[0014] Hereinafter, embodiments of the present disclosure will be described with reference to the drawings. In the description of the drawings, the same reference numerals are assigned to the same elements, and redundant descriptions are omitted.

[0015] As shown in FIG. 1, the ceiling transfer vehicle 1 travels along a traveling rail 101 laid near the ceiling of a clean room where semiconductor devices are manufactured. The ceiling transfer vehicle 1 transfers a FOUP (article) 90, which is a container in which a plurality of semiconductor wafers are accommodated. The ceiling transfer vehicle 1 transfers the FOUP 90 to a load port (transfer destination) 102 provided in a processing apparatus that performs various processes on the semiconductor wafers. That is, the ceiling transfer vehicle 1 retrieves the FOUP 90 disposed on the placement surface 102a of the load port 102, or disposes the FOUP 90 on the placement surface 102a of the load port 102.

[0016] The ceiling transfer vehicle 1 includes a traveling unit 2, a lateral feed unit 3, a rotating unit 4, a lifting unit 5, a gripper unit 6, and a control device 7. The traveling unit 2 travels along the traveling rail 101, for example, by receiving power supply without contact from a high-frequency current line laid along the traveling rail 101. The lateral feed unit 3 moves the rotating unit 4, the lifting unit 5, and the gripper unit 6 in a lateral direction with respect to the direction in which the traveling rail 101 extends. The rotating unit 4 rotates the lifting unit 5 and the gripper unit 6 in a horizontal plane. The lifting unit 5 has a plurality of belts (suspension members) 5a, and the gripper unit 6 is attached to the lower end of the belt 5a. The lifting unit 5 raises and lowers the gripper unit 6 by feeding out or winding up the plurality of belts (suspension members) 5a. The gripper unit 6 grips the flange portion 91 of the FOUP 90 by closing a pair of claw members 6a. The gripper unit 6 releases the gripping state of the flange portion 91 by opening the pair of claw members 6a. The control device 7 is an electronic control unit composed of a CPU (processor), a ROM, a RAM, etc. The control device 7 controls the operations of each part of the ceiling transfer vehicle 1.

[0017] In FIG. 1, the XYZ axes are also shown. The Y direction in the figure is the traveling direction of the ceiling transfer vehicle 1, and the X direction in the figure is the lateral movement direction in which the gripper unit 6 etc. are moved by the lateral feed unit 3. The Z direction in the figure is the vertical direction. The ceiling transfer vehicle 1 lowers the gripper unit 6 along the Z direction and raises the gripper unit 6 along the Z direction. The traveling direction (Y direction; the first horizontal direction) of the ceiling transfer vehicle 1 and the lateral movement direction (X direction; the second horizontal direction) by the lateral feed unit 3 are each orthogonal to the vertical direction (Z direction) and orthogonal to each other. In FIGS. 3, 5, and 7 referred to in the following description, the XYZ axes are also shown in the same way.

[0018] The ceiling transfer vehicle 1 further includes, for example, a center cone (positioning portion) 8, a dog 10, and a flange detection unit 20. A recess 91a that is open upward is formed at the center of the flange portion 91 of the FOUP 90. The center cone 8 is a member that fits into the recess 91a of the flange portion 91 for positioning the gripper unit 6 with respect to the FOUP 90. The center cone 8, the dog 10, and the flange detection unit 20 are provided on the gripper unit 6. The center cone 8, the dog 10, and the flange detection unit 20 are attached to a base portion (not shown) of the gripper unit 6. The center cone 8 is biased downward by a spring (not shown) attached to the base portion and is vertically movable with respect to the gripper unit 6.

[0019] When picking up the FOUP 90 placed on the load port 102, the control device 7 controls the gripper unit 6 to descend, and the center cone 8 fits into the recess 91a of the flange portion 91. When the gripper unit 6 further descends due to its own weight, the center cone 8 relatively ascends with respect to the gripper unit 6. The control device 7 recognizes that the gripper unit 6 has reached the gripping position P1 (see FIG. 3) by means of a photointerrupter composed of a light projecting portion and a light receiving portion of the flange detection unit 20 and a light shielding plate portion of the dog 10 passing on its optical axis. The control device 7 stops the descent of the gripper unit 6 and closes a pair of claw members 6a on the gripper unit 6. When the claw members 6a close, the claw members 6a enter below the flange portion 91. Thereafter, the control device 7 starts the ascent of the gripper unit 6 by the lifting unit 5. The operation when the gripper unit 6 holding the FOUP 90 places the FOUP 90 on the placement surface 102a of the load port 102, that is, the unloading operation, is opposite to the operation during picking up.

[0020] The recognition of the position of the gripper unit 6 using the center cone 8, the dog 10, and the flange detection unit 20, and the recognition of the gripping state of the FOUP 90 by the gripper unit 6 are realized, for example, by the configuration and method described in the above Patent Document 1 (International Publication No. 2018 / 179931). However, the recognition of the position of the gripper unit 6 and the recognition of the gripping state of the FOUP 90 by the gripper unit 6 may be performed by other known configurations and methods.

[0021] The elevating unit 5 has an elevating motor (not shown). The elevating motor lowers the gripper unit 6 by feeding out the belt 5a and raises the gripper unit 6 by winding up the belt 5a. The elevating motor is driven and controlled by the control device 7. The control device 7 can detect the feeding amount (belt length) of the belt 5a by receiving a signal related to the rotation from the elevating motor. The control device 7 can detect the position (height position) of the gripper unit 6 based on the feeding amount (belt length) of the belt 5a.

[0022] As shown in FIG. 5, the ceiling transfer vehicle 1 includes a shaking detection unit 40 that detects the shaking of the gripper unit 6. The shaking detection unit 40 is attached to, for example, the elevating unit 5. The shaking detection unit 40 has, for example, a light projecting unit and a light receiving unit, and these light projecting unit and light receiving unit are exposed downward. On the other hand, a reflecting plate 41 is attached to the upper surface of the gripper unit 6. With the state where the gripper unit 6 hangs straight down (that is, the state where the belt 5a extends in the vertical direction) as a reference, the shaking detection unit 40 emits light downward and detects the reflected light reflected by the reflecting plate 41, thereby being able to detect that the gripper unit 6 is not shaking. In other words, the shaking detection unit 40 can detect that the gripper unit 6 is shaking by a predetermined amount or more by not detecting the reflected light (being unable to detect the reflected light). The shaking detection unit 40 outputs (transmits) the detection result of the shaking of the gripper unit 6 to the control device 7.

[0023] Next, a configuration for detecting an abnormality in the gripper unit 6 (for example, inclination, shaking, impact, etc. occurring in the gripper unit 6) will be described. An accelerometer 9 (see FIG. 1) is mounted on the gripper unit 6 of the present embodiment. The accelerometer 9 is attached to, for example, the base portion of the gripper unit 6. The accelerometer 9 is a three-axis acceleration sensor capable of detecting acceleration in each of, for example, the Z direction, the X direction, and the Y direction. The type of the accelerometer 9 is not particularly limited. As the accelerometer 9, for example, a capacitive sensor or a piezoresistive sensor may be applied. Note that three uniaxial acceleration sensors capable of detecting acceleration in the Z direction, the X direction, and the Y direction, respectively, may be mounted on the gripper unit 6.

[0024] The control device 7 determines whether there is an abnormality in the gripper unit 6. With reference to FIG. 2, each function of the control device 7 will be described. FIG. 2 is a functional block diagram of the control device 7 in the ceiling transfer cart 1. The control device 7 includes a position acquisition unit 31, a shaking acquisition unit 32, an acceleration acquisition unit 33, a storage unit 34, and an abnormality determination unit 36. Signals output from the lifting motor of the belt 5a and the flange detection unit 20 are input to the position acquisition unit 31, and based on the input signals, the position (height position) of the gripper unit 6 is acquired. By acquiring the position of the gripper unit 6, the position acquisition unit 31 recognizes the lifting operation state of the gripper unit 6. The lifting operation state of the gripper unit 6 includes a state where the gripper unit 6 stops at the gripping position P1 (see FIG. 3), a state where the gripper unit 6 is ascending, and a state where the gripper unit 6 is descending. The position acquisition unit 31 monitors that the gripper unit 6 reaches the deceleration start position P2 (see FIG. 5) when ascending while the gripper unit 6 is ascending. Also, the position acquisition unit 31 monitors that the gripper unit 6 reaches the deceleration start position P3 (see FIG. 7) when descending while the gripper unit 6 is descending. Signals output from the shaking detection unit 40 are input to the shaking acquisition unit 32, and the shaking (shaking amount) of the gripper unit 6 is acquired. The acceleration acquisition unit 33 receives a detection signal output from the accelerometer 9 in the gripper unit 6 and acquires the acceleration generated in the gripper unit 6.

[0025] The abnormality determination unit 36 determines the presence or absence of an abnormality in the gripper unit 6 based on the lifting and lowering operation state of the gripper unit 6 and the detection result of the accelerometer 9. The storage unit 34 stores various threshold values used in the abnormality determination unit 36. More specifically, the storage unit 34 stores a first set value, which is a threshold value for determining the presence or absence of an abnormality in the gripper unit 6 when the gripper unit 6 stops at the gripping position P1 (see FIG. 3). The first set value is, for example, a threshold value related to the acceleration in the Z direction (the inclination with respect to the Z direction) of the gripper unit 6. The storage unit 34 also stores a second set value, which is a threshold value for determining the presence or absence of an abnormality in the gripper unit 6 during the lifting and lowering operation (lifting and lowering state) of the gripper unit 6. The second set value is, for example, a threshold value related to the acceleration in the Z direction of the gripper unit 6. The second set value may be, for example, a threshold value related to the acceleration in the X direction and / or the Y direction of the gripper unit 6.

[0026] The control device 7 further includes a lifting and lowering control unit 37, a gripping control unit 38, and a notification control unit 39. The lifting and lowering control unit 37 controls the lifting and lowering motor of the lifting and lowering unit 5 to lower, stop, or raise the gripper unit 6. The gripping control unit 38 controls the opening and closing of the claw members 6a of the gripper unit 6 when the position acquisition unit 31 recognizes that the gripper unit 6 is located at the gripping position P1. The notification control unit 39 activates a notification device such as an alarm installed in, for example, a host controller when the abnormality determination unit 36 determines that an abnormality has occurred in the gripper unit 6 to issue an error notification.

[0027] Next, with reference to FIG. 3 and subsequent figures, a method for determining the presence or absence of an abnormality in the gripper unit 6 in various lifting operation states of the ceiling transfer vehicle 1 will be described. FIG. 3 is a diagram showing a detection state of the presence or absence of an abnormality in the gripping control of the gripper unit 6. FIG. 4 is a flowchart showing a processing procedure in the gripping control. As shown in FIGS. 3 and 4, the lifting control unit 37 controls the gripper unit 6 in the state of gripping (holding) the FOUP 90 to descend (step S11). Subsequently, the position acquisition unit 31 recognizes that the gripper unit 6 is located at the gripping position P1 based on the signal output from the flange detection unit 20 (step S12). The lifting control unit 37 controls the gripper unit 6 to stop descending (step S13). In the state where the gripper unit 6 has stopped at the gripping position P1, the acceleration acquisition unit 33 acquires the detected value of the acceleration output from the accelerometer 9 (step S14). The abnormality determination unit 36 determines whether or not the detected value in the accelerometer 9 exceeds a preset first set value (step S15).

[0028] When the gripper unit 6 is positioned directly above the FOUP 90 and the center cone 8 is properly fitted into the recess 91a of the flange portion 91, the gripper unit 6 maintains a substantially horizontal posture (see FIG. 3). In such a case, the detected value in the accelerometer 9 is equal to or less than the first set value, and the abnormality determination unit 36 determines that there is no abnormality (step S15; NO). Then, the gripping control unit 38 performs gripping control on the gripper unit 6 to close the claw members 6a and execute a gripping operation (step S16). In the gripping operation, the claw members 6a of the gripper unit 6 enter below the flange portion 91. On the other hand, for example, when a fitting failure as shown in FIG. 9(b) occurs, the detected value in the accelerometer 9 exceeds the first set value, and the abnormality determination unit 36 determines that there is an abnormality (step S15; YES). Then, the notification control unit 39 controls the notification device to issue an error (step S17).

[0029] By the series of controls described above, the gripping control in the gripper unit 6 is executed. When the gripping control cannot be properly performed due to a displacement of the FOUP 90 or the like, the gripper unit 6 tilts, and this is detected by the accelerometer 9. Therefore, an error is reported without executing the gripping operation (that is, without closing the claw member 6a). The first set value is set to a value corresponding to an inclination larger than the maximum inclination of the gripper unit 6 that can occur when the center cone 8 is properly fitted.

[0030] According to the ceiling transporter 1 of the present embodiment, the accelerometer 9 detects the acceleration and the like generated in the gripper unit 6. The control device 7 determines the presence or absence of an abnormality in the gripper unit 6 based on the lifting and lowering operation state of the gripper unit 6 and the detection result of the accelerometer 9. If only the detection result of the accelerometer 9 is used, there is a possibility that an abnormality may be determined even though the gripper unit 6 is operating normally. However, by taking into account the lifting and lowering operation state of the gripper unit 6 (the stop state in the above example), the presence or absence of an abnormality in the gripper unit 6 can be reliably detected.

[0031] The control device 7 determines the presence or absence of an abnormality in the gripper unit 6 based on whether or not the detected value of the accelerometer 9 in the state where the gripper unit 6 has stopped at the gripping position P1 exceeds a preset first set value. Therefore, it is possible to reliably detect whether there is a problem even if the gripping operation is started. For example, when the gripper unit 6 attempts to grip the FOUP 90, it is possible to prevent an excessive impact from being applied to the FOUP 90.

[0032] The accelerometer 9 can detect the acceleration of the gripper unit 6 in the Z direction, X direction, and Y direction. Therefore, the inclination of the gripper unit 6 can be detected in the stopped state of the gripper unit 6.

[0033] Next, with reference to FIGS. 5 and 6, a method for determining the presence or absence of an abnormality in the gripper unit 6 in the raised state will be described. FIG. 5 is a diagram showing a detection state of the presence or absence of an abnormality in the upward control when the gripper unit 6 grasps an object. FIG. 6 is a flowchart showing a processing procedure in the upward control. As shown in FIGS. 5 and 6, the elevating control unit 37 performs upward control on the gripper unit 6 in a state where the FOUP 90 is gripped (held) (step S21). After the start of the upward movement of the gripper unit 6, acquisition and monitoring of the sway by the sway acquisition unit 32 are executed (step S22), and monitoring of impact detection by the acceleration acquisition unit 33 and the abnormality determination unit 36 is started (step S23). While the light transmission and reception between the sway detection unit 40 and the reflector 41 are established, no error is reported by the sway acquisition unit 32. However, even when such sway is within the allowable range, an impact or vibration may be applied to the upward-moving gripper unit 6. When the acceleration acquisition unit 33 acquires the detected value of the acceleration output from the accelerometer 9 in step S23, the abnormality determination unit 36 determines whether the detected value in the accelerometer 9 exceeds a preset second set value (step S24).

[0034] When the abnormality determination unit 36 determines that the detected value in the accelerometer 9 is equal to or less than the second set value (step S24; NO), the upward control of the gripper unit 6 is continued, and the position acquisition unit 31 recognizes that the gripper unit 6 is located at the deceleration start position P2 during upward movement (step S25). This deceleration start position P2 during upward movement may be recognized by a sensor (not shown) that detects that the gripper unit 6 has risen near the elevating unit 5, as indicated by the virtual line in FIG. 5. When the gripper unit 6 reaches the deceleration start position P2 during upward movement, the abnormality determination unit 36 ends the monitoring of impact detection (step S26). Thereafter, the elevating control unit 37 further raises the gripper unit 6 at a decelerated elevating speed, and the gripper unit 6 reaches the origin position (upper end) (step S27).

[0035] When an impact, vibration, or the like is applied to the ascending gripper unit 6, in step S24, the abnormality determination unit 36 determines that the detected value of the accelerometer 9 exceeds the second set value (step S24; YES), and the notification control unit 39 controls the notification device to issue an error (step S28).

[0036] Subsequently, with reference to FIGS. 7 and 8, a method for determining the presence or absence of an abnormality in the gripper unit 6 in the descending state will be described. FIG. 7 is a diagram showing a detection state of the presence or absence of an abnormality in the descending control during unloading of the gripper unit 6. FIG. 8 is a flowchart showing the processing procedure in the descending control. As shown in FIGS. 7 and 8, the elevating control unit 37 controls the gripper unit 6 in the state of gripping (holding) the FOUP 90 to descend (step S31). After the start of the descent of the gripper unit 6, acquisition and monitoring of the sway by the sway acquisition unit 32 are executed (step S32), and monitoring of impact detection by the acceleration acquisition unit 33 and the abnormality determination unit 36 is started (step S33). While the light transmission and reception between the sway detection unit 40 and the reflector 41 are established, no error is reported by the sway acquisition unit 32. However, even when such sway is within the allowable range, an impact, vibration, or the like may be applied to the descending gripper unit 6. When the acceleration acquisition unit 33 acquires the detected value of the acceleration output from the accelerometer 9 in step S33, the abnormality determination unit 36 determines whether the detected value of the accelerometer 9 exceeds a preset second set value (step S34).

[0037] Note that the second set value in the descending control (control during unloading) is the same as the second set value in the above-described ascending control (control during loading), but they may be different. The second set value in the descending control may be smaller than the second set value in the ascending control. The second set value in the descending control may be larger than the second set value in the ascending control. The second set value is set to a value exceeding a predetermined acceleration range of the gripper unit 6 that can occur in the normal ascending control or normal descending control of the gripper unit 6.

[0038] When the abnormality determination unit 36 determines that the detected value of the accelerometer 9 is equal to or less than the second set value (step S34; NO), the lowering control of the gripper unit 6 is continued, and the position acquisition unit 31 recognizes that the gripper unit 6 is located at the deceleration start position P3 during lowering (step S35). This deceleration start position P3 during lowering is the transition start position to auto-teaching or creep control, as indicated by the virtual line in FIG. 7, and is set at a position slightly higher than the gripping position P1 described above. When the gripper unit 6 reaches the deceleration start position P3 during lowering, the abnormality determination unit 36 terminates the monitoring of impact detection (step S36). Thereafter, the lifting and lowering control unit 37 further lowers the gripper unit 6 at a decelerated lowering speed, and the position acquisition unit 31 recognizes that the gripper unit 6 is located at the gripping position P1 (step S37). Then, the gripping control unit 38 performs release control on the gripper unit 6 to open the claw member 6a and release the gripping state by the gripper unit 6 (step S38).

[0039] When an impact, vibration, or the like is applied to the lowering gripper unit 6, in step S34, the abnormality determination unit 36 determines that the detected value of the accelerometer 9 exceeds the second set value (step S34; YES), and the notification control unit 39 controls the notification device to issue an error (step S39).

[0040] According to the ceiling transfer cart 1 of the present embodiment, the accelerometer 9 detects the acceleration and the like generated in the gripper unit 6. The control device 7 determines the presence or absence of an abnormality in the gripper unit 6 based on the lifting and lowering operation state of the gripper unit 6 and the detection result of the accelerometer 9. If only the detection result of the accelerometer 9 is used, there is a possibility that an abnormality may be determined even though the gripper unit 6 is operating normally. However, by taking into account the lifting and lowering operation state of the gripper unit 6 (the ascending state or the descending state in the above example), the presence or absence of an abnormality in the gripper unit 6 can be reliably detected.

[0041] The control device 7 determines whether there is an abnormality in the gripper unit 6 based on whether the detected value of the accelerometer 9 during the lifting operation of the gripper unit 6 exceeds a preset second set value. Therefore, it is possible to reliably detect whether there is a problem even if the lifting operation is continued. For example, when the gripper unit 6 moves up or down, it is possible to prevent an excessive impact from being applied to the FOUP 90, etc.

[0042] The accelerometer 9 can detect the acceleration of the gripper unit 6 in the Z direction, X direction, and Y direction. Therefore, it is also possible to detect horizontal shaking or impact in the gripper unit 6.

[0043] As described above, the embodiments of the present disclosure have been described, but the present invention is not limited to the above embodiments. For example, the configuration of the accelerometer 9 is not limited to the triaxial acceleration sensor in the above embodiment. One single-axis accelerometer capable of detecting the acceleration in the Z direction may be mounted on the gripper unit 6. Even in this case, it is possible to detect an abnormality (such as shaking or impact) that occurs in the Z direction in the gripper unit 6.

[0044] As the flange detection unit 20, a detection unit of a type different from that of the above embodiment may be adopted. The relative upward movement of the center cone 8 with respect to the gripper unit 6 may be detected by a configuration different from that of the flange detection unit 20. Also, as long as it is possible to fit into some recess formed in the flange portion 91 of the FOUP 90, a positioning unit other than the center cone 8 may be applied. The article conveyed by the ceiling carrier 1 may be a container other than the FOUP 90.

[0045] The downward control of the gripper unit 6 described with reference to FIGS. 7 and 8 is not limited to unloading control, and may also be applied when performing auto-teaching.

[0046] The constituent elements of one aspect of the present disclosure are described as follows. [1] A traveling unit that travels along a traveling rail, The lifting part provided on the traveling part, A gripper unit that is lifted by the lifting part and grips an article, An accelerometer mounted on the gripper unit, A control device that recognizes the lifting operation state of the gripper unit and determines the presence or absence of an abnormality in the gripper unit based on the lifting operation state and the detection result of the accelerometer. The overhead transporter is provided with these components. [2] The control device determines the presence or absence of an abnormality in the gripper unit based on whether or not the detected value of the accelerometer in a state where the gripper unit has stopped at the gripping position exceeds a preset first set value. The overhead transporter according to [1]. [3] The control device determines the presence or absence of an abnormality in the gripper unit based on whether or not the detected value of the accelerometer during the lifting operation of the gripper unit exceeds a preset second set value. The overhead transporter according to [1] or [2]. [4] The accelerometer can detect at least the acceleration of the gripper unit in the vertical direction. The overhead transporter according to any one of [1] to [3]. [5] The accelerometer can detect the acceleration of the gripper unit in a first horizontal direction and a second horizontal direction that are orthogonal to each other and orthogonal to the vertical direction respectively. The overhead transporter according to [4].

Explanation of Signs

[0047] 1... Overhead transporter, 2... Traveling part, 5... Lifting part, 6... Gripper unit, 6a... Claw member, 7... Control device, 8... Center cone, 9... Accelerometer, 20... Flange detection part, 36... Abnormality determination part, 37... Lifting control part, 38... Gripping control part, 40... Vibration detection part, 90... FOUP (article), 101... Traveling rail, P1... Gripping position, P2... Deceleration start position during ascent, P3... Deceleration start position during descent.

Claims

1. A traveling unit that travels along a traveling rail, a lifting unit provided on the traveling unit, a gripper unit that is lifted and lowered by the lifting unit and grips an article, an accelerometer mounted on the gripper unit, and a control device that recognizes the lifting operation state of the gripper unit and determines the presence or absence of an abnormality in the gripper unit based on the lifting operation state and the detection result of the accelerometer. The control device determines the presence or absence of the inclination as the abnormality in the gripper unit based on whether or not a detection value of the accelerometer in a state where the gripper unit has stopped at a gripping position exceeds a first set value related to an inclination of the gripper unit with respect to the vertical direction set in advance. The overhead transporter.

2. (Deleted)

3. (Deleted)

4. The overhead transporter according to claim 1, wherein the accelerometer can detect at least an acceleration of the gripper unit in the vertical direction.

5. The overhead transporter according to claim 4, wherein the accelerometer can detect accelerations of the gripper unit in a first horizontal direction and a second horizontal direction that are orthogonal to each other and orthogonal to the vertical direction, respectively.

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