Overhead transport vehicle system and method for correcting angle of holding unit

Abstract

This overhead transport vehicle system comprises: a holding unit that holds an article; a lifting device that lifts and lowers the holding unit; and a correction mechanism that is controlled by a controller and corrects the angle of the holding unit. The overhead transport vehicle system comprises one angle measurement device that measures the angle of the holding unit with respect to a horizontal plane at each of a plurality of height levels within a lifting range of the holding unit. The controller stores measurement results of a plurality of angles obtained by the angle measurement device, and controls the correction mechanism on the basis of the measurement results of the angles at each of the height levels.

Description

Ceiling Transfer Cart System and Angle Correction Method for Holding Unit

[0001] The present disclosure relates to a ceiling transfer cart system and an angle correction method for a holding unit.

[0002] Regarding the angle adjustment of the holding unit in the ceiling transfer cart system, studies have been made as described in, for example, Patent Document 1. Patent Document 1 discloses a ceiling transfer cart system including a gripper unit that holds an article, a lifting device that raises and lowers the gripper unit, and a correction mechanism that is controlled by a controller and corrects the angle of the gripper unit. This system includes a measurement unit and a measured unit for measuring the state of the ceiling transfer cart, and automatically corrects (adjusts) the horizontal position, horizontal angle, and inclination of the holding unit by these. Also, the state of the ceiling transfer cart is periodically acquired using a maintenance stand.

[0003] International Publication No. 2022 / 107448

[0004] In the above-described conventional system, the maintenance stand has first and second mounting tables on which the measurement units are respectively placed. The second mounting table is provided at a relatively higher position than the first mounting table. In this system, a mounting table is required for each height level where measurement and correction are necessary, and sensors, actuators, etc. are required for each mounting table, so the configuration becomes complicated. There is a need for a technology to easily correct the angle of the holding unit at a plurality of height levels of the gripper unit (holding unit).

[0005] The present disclosure describes a ceiling transfer cart system and an angle correction method for a holding unit that can easily correct the angle of the holding unit at a plurality of height levels.

[0006] [1] One aspect of the present disclosure is an overhead transport vehicle system comprising a holding unit for holding articles, a lifting device for raising and lowering the holding unit, and a correction mechanism controlled by a controller for correcting the angle of the holding unit, wherein the system includes one angle measuring device for measuring the angle of the holding unit with respect to the horizontal plane at each of a plurality of height levels within the lifting range of the holding unit, and the controller stores the measurement results of the plurality of angles obtained by the angle measuring device and controls the correction mechanism based on the measurement results of the angles at each of the height levels.

[0007] In the overhead transport system of [1], the angle of the holding unit with respect to the horizontal plane at each of the multiple height levels is measured by a single angle measuring device. Therefore, complexity of the configuration is prevented. In addition, calibration of the angle measuring device only needs to be done for one unit, and maintaining measurement accuracy is easy.

[0008] [2] In the overhead transport vehicle system described in [1] above, the angle measuring device may include a measuring position below the lifting range of the holding unit, or at least three laser distance sensors provided on the holding unit. By using at least three laser distance sensors, the angle of the holding unit with respect to the horizontal plane at each of the multiple height levels can be easily measured.

[0009] [3] In the overhead transport vehicle system described in [1] or [2] above, the controller may stop the lifting device at each height level, control the correction mechanism to correct the angle of the holding unit, and then determine whether the angle measurement result obtained again by the angle measuring device at the height level where the device is stopped falls within the allowable range. In this case, depending on the determination result, it can be decided whether or not to move to the next height level. Measurement and verification at multiple height levels can be carried out quickly.

[0010] [4] In the overhead transport vehicle system described in [3] above, the controller may, when it determines that the angle measurement result obtained again by the angle measuring device is within the allowable range, control the lifting device to move the holding unit to another height level and control the correction mechanism based on the angle measurement result at that other height level. In this case, the angle of the holding unit at each height level can be corrected more accurately.

[0011] [5] In any one of the overhead transport vehicle systems described in [1] to [4] above, the controller stores the angle measurement results and the angle correction history by the correction mechanism for each overhead transport vehicle, and the measurement results and correction history can be displayed on the display unit for each overhead transport vehicle. In this case, the administrator (operator, etc.) can easily check the measurement results and correction history for each overhead transport vehicle.

[0012] [6] In another aspect of the present disclosure, a method for correcting the angle of a holding unit in an overhead transport vehicle system is provided, comprising: a holding unit for holding articles; a lifting device for raising and lowering the holding unit; and a correction mechanism controlled by a controller for correcting the angle of the holding unit. In the method for correcting the angle of a holding unit, the angle of the holding unit with respect to the horizontal plane at each of a plurality of height levels within the lifting range of the holding unit is measured by a single angle measuring device, the measurement results of the plurality of angles obtained by the angle measuring device are stored, and the angle of the holding unit is corrected based on the measurement results of the angles at each height level.

[0013] According to the angle correction method for the holding unit in [6], the angle of the holding unit with respect to the horizontal plane at each of the multiple height levels is measured by a single angle measuring device. This prevents the configuration from becoming complex. Furthermore, calibration and other adjustment work on the angle measuring device can be performed with just one device, making it easy to maintain measurement accuracy.

[0014] According to this disclosure, the angle of the holding unit can be easily corrected at multiple height levels.

[0015] Figure 1 is a diagram showing an example of an overhead transport vehicle and an angle measuring device in an overhead transport vehicle system according to one embodiment of the present disclosure. Figure 2 is a front view of the lifting device. Figure 3 is a perspective view of the angle measuring device in Figure 1. Figure 4 is a perspective view of the measuring unit and the unit to be measured in the angle measuring device. Figure 5 is a schematic diagram showing the measurement targets of each distance sensor when the measuring unit measures the unit to be measured. Figure 6 is a block diagram showing the functional configuration of the overhead transport vehicle system. Figure 7 is a sequence diagram showing the angle correction method of the holding unit in the overhead transport vehicle system. Figure 8 is a diagram showing the state in which angle measurement and correction are being performed at the lowest position (first height level). Figure 9 is a diagram showing the state in which angle measurement and correction are being performed at an intermediate position (second height level). Figure 10 is a diagram showing an example of the configuration of an overhead transport vehicle system according to another embodiment of the present disclosure. Figure 11 is a diagram showing an example of the display of measurement results and correction history on the display unit of the angle measuring device.

[0016] Embodiments of this disclosure will be described below with reference to the drawings. In the description of the drawings, the same elements will be denoted by the same reference numerals, and redundant descriptions will be omitted.

[0017] Referring to Figure 1, the overall configuration of the overhead transport system S of this embodiment will be described. As shown in Figure 1, the overhead transport system S is applied, for example, to a cleanroom (semiconductor factory) where semiconductor devices are manufactured. The overhead transport system S comprises a track 200 laid near the ceiling of a building that constitutes a cleanroom, etc., and a plurality of overhead transport vehicles 1 that travel along the track 200. The number of overhead transport vehicles 1 is appropriately determined according to the required transport capacity, etc.

[0018] The track 200 is suspended from the ceiling, for example. The track 200 is a predetermined one-way route for the overhead transport vehicle 1 to travel on. The track 200 passes over, for example, a number of ports (not shown). The layout of the track 200 may be appropriately determined according to the arrangement of the processing equipment (not shown) in the cleanroom. Each port is installed, for example, on the floor surface F at the horizontal end of the processing equipment. The arrangement of the ports may also be appropriately determined. At least one port may be positioned so as not to overlap the track 200 in a plan view.

[0019] In the overhead transport vehicle system S, each overhead transport vehicle 1 travels along a track 200. Each overhead transport vehicle 1 transports goods (not shown). The goods are, for example, reticle pods that house reticles. Each overhead transport vehicle 1 transfers goods between ports. The overhead transport vehicle system S may also be equipped with storage shelves (not shown) suspended from the ceiling, or with stockers (not shown) installed on the floor surface F.

[0020] In the overhead transport vehicle system S of this embodiment, for example, in each of the multiple overhead transport vehicles 1, a teaching mode is performed to measure the angle (or inclination) of the holding unit 7 with respect to the horizontal plane, and to correct the angle. The "teaching mode" can also be called the "maintenance mode". The overhead transport vehicle 1 is capable of holding and transporting articles, and is also capable of holding and raising / lowering the unit to be measured 90, which is prepared for the above measurement and correction. With the unit to be measured 90 in its possession, the overhead transport vehicle 1 receives a movement instruction from a portable device 400 operated by an operator, and performs a predetermined angle measurement and angle correction operation in cooperation with the load port device 300.

[0021] Next, the configuration of the overhead transport vehicle 1 will be described. Figure 1 shows the overhead transport vehicle 1 holding the unit to be measured 90. Since the configuration for holding an item and the configuration for holding the unit to be measured 90 are the same in the overhead transport vehicle 1, the following explanation will focus on the case where the unit to be measured 90 is held and raised and lowered. The explanation of the case where an item is held and transported will be omitted.

[0022] The overhead transport vehicle 1 comprises a frame unit 2, a travel unit 3, a lateral unit 4, a lifting drive unit (lifting device) 6, and a holding unit 7. The frame unit 2 includes frames provided on the front and rear sides in the extending direction (travel direction) of the track 200. The travel unit 3 travels along the track 200 by receiving power non-contactually from, for example, high-frequency current lines laid along the track 200. As the drive method for the travel unit 3, an electric motor drive method may be adopted, a linear motor drive method may be adopted, or other known drive methods may be adopted. The lateral unit 4 moves the lifting drive unit 6 and the holding unit 7 laterally (to the side in the travel direction of the overhead transport vehicle 1).

[0023] The lifting drive unit 6 raises and lowers the holding unit 7. The lifting drive unit 6 raises and lowers the holding unit 7 by, for example, winding or unwinding three belts B. The holding unit 7 holds the unit to be measured 90 in a specified orientation. The holding unit 7 has, for example, a pair of grippers 8, 8. The pair of grippers 8, 8 are opened and closed by a drive motor and a link mechanism to grip the unit to be measured 90 or to release the grip of the unit to be measured 90.

[0024] The overhead transport vehicle 1 may have known configurations other than those described above. A rotation unit may be provided between the lateral unit 4 and the lifting drive unit 6 to rotate the lifting drive unit 6 around a central axis (rotation axis) along the Z direction. Another rotation unit may be provided between the lifting drive unit 6 and the holding unit 7 to rotate the holding unit 7 around a central axis (rotation axis) along the Z direction.

[0025] The overhead transport vehicle 1 has a transport vehicle controller 9. The transport vehicle controller 9 is located, for example, within the frame unit 2. The transport vehicle controller 9 is a controller that controls each part of the overhead transport vehicle 1. The transport vehicle controller 9 controls the travel unit 3, the lateral unit 4, the lifting drive unit 6, and the holding unit 7. The transport vehicle controller 9 is an electronic control unit composed of a processor such as a CPU (Central Processing Unit), ROM (Read-only memory), and RAM (Random Access Memory).

[0026] Communication units 210 are provided at appropriate locations on the side of the track 200. The communication units 210 can communicate via optical communication with the transport vehicle controller 9 of the overhead transport vehicle 1, and can also communicate with the port controller 310 of the load port device 300, which will be described later, via a communication line 211.

[0027] Furthermore, the overhead transport vehicle 1 has a communication display unit 15 provided on one side of the frame unit 2 (for example, the front or rear frame). The communication display unit 15 is capable of optical communication with a portable device 400 held by the operator. The portable device 400 is, for example, a terminal capable of one-way communication using infrared (communication toward the overhead transport vehicle 1). The portable device 400 may also be a tablet remote control or the like capable of two-way communication. The communication display unit 15 includes an optical display interface 16 with excellent display capabilities so that it can be seen by the operator even on the overhead transport vehicle 1 located directly below the track 200. The optical display interface 16 displays the mode status of the overhead transport vehicle 1 by color and flashing cycle, and reacts to the reception of a remote control signal by flashing.

[0028] The overhead transport vehicle system S includes a load port device (angle measuring device) 300 that measures the angle of the holding unit 7 of the overhead transport vehicle 1 at each of several different height levels. For example, only one load port device 300 is provided in the overhead transport vehicle system S. The load port device 300 is located below the track 200. As shown in Figure 3, the load port device 300 has a housing 301 installed on the floor, a measuring unit 80 placed on the upper surface 302 of the housing 301, and a cover 304 provided on the housing 301 that surrounds the sides of the measuring unit 80. The load port device 300 further includes a port controller 310 provided inside the housing 301 and a display unit 303 that displays various information related to the measurement and correction of the angle of the holding unit 7. The port controller 310 is an electronic control unit composed of a processor such as a CPU, ROM and RAM, etc. The port controller 310 may also be a PLC (Programmable Logic Controller). In Figure 3, the unit to be measured 90 is shown being held by the holding unit 7, but the holding unit 7 and the gripper 8 are not shown.

[0029] Next, with reference to Figure 2, the configuration of the lifting drive unit 6, which includes two linear motion mechanisms (correction mechanisms) 67 for correcting the angle of the holding unit 7, will be described. As shown in Figure 2, the lifting drive unit 6 includes a base (main body) 61, a support part 62, a plurality of (for example, three) winding drums 63, a drive motor (winding drive unit) 63A, a first idler roller (guide roller) 65A, a second idler roller (guide roller) 65B, a third idler roller (guide roller) 64, a linear motion mechanism (position adjustment unit) 67, a swinging member 68, and three (or more) belts B.

[0030] The base 61 supports the winding drum 63, the first idler roller 65A, and the third idler roller 64 via the support portion 62. The support portion 62 rotatably supports the three winding drums 63. The three winding drums 63 are arranged in the front-rear direction and each of the three belts B is wound up or unwound by drive motor 63A. The support portion 62 pivotably supports the first idler roller 65A and one end 68A of the oscillating member 68.

[0031] Each winding drum 63 is mounted to the base 61 via a support 62 so that it can rotate. A drive motor 63A is the drive source for rotating each winding drum 63 and is fixed to the base 61. The three winding drums 63 are driven by a single drive motor 63A by being mounted on a common pivot shaft (not shown) or by being connected by an interlocking mechanism (not shown).

[0032] One end of each belt B is connected to the holding unit 7, and the other end of each belt B is connected to each winding drum 63. In this embodiment, the three belts B are arranged to suspend the three points of the holding unit 7.

[0033] The first idler roller 65A and the second idler roller 65B guide the movement of, for example, two belts B. The first idler roller 65A is provided on the support portion 62 and does not move relative to the base 61. The second idler roller 65B moves relative to the base 61.

[0034] The linear motion mechanism 67 mainly comprises a drive motor 67A, a screw shaft 67B, and a ball nut 67C, and is a known mechanism that converts the rotational motion of the drive motor 67A into linear motion. The linear motion mechanism 67 is fixed to the base 61 via a bracket 66. The ball nut 67C moves along the screw shaft 67B when driven by the drive motor 67A, and the other end 68B of the oscillating member 68 is pivotably connected to it. The linear motion mechanism 67 moves the position of the second idler roller 65B so that the connection portion of the belt B to the holding unit 7 (one end of the belt B) moves in the vertical direction. Alternatively, the oscillating member 68 may be changed to a vertically movable member cantilevered by the linear motion mechanism 67, and the position of the second idler roller 65B may be moved linearly by moving this member up and down.

[0035] In this embodiment, the overhead transport vehicle 1 can adjust the angle (tilt) of the holding unit 7 with respect to the horizontal plane by operating both or one of the two linear motion mechanisms 67. Alternatively, another known correction mechanism for correcting the angle of the holding unit 7 may be used instead of the linear motion mechanisms 67 described above.

[0036] Here, each of the overhead transport vehicles 1 can measure, at a desired timing, how much each holding unit 7 is tilted at each of the multiple different height levels (the angle at each of the multiple height levels), and if the angle exceeds the allowable value, it can perform correction by the linear motion mechanism 67 at each height level.

[0037] The measurement unit 80 and the unit to be measured 90 will be described in detail. As shown in Figures 4 and 5, the measurement unit 80 and the unit to be measured 90 are units (or jigs) for acquiring the state of the overhead transport vehicle 1 without human intervention. Figure 4 is a perspective view of the measurement unit 80 and the unit to be measured 90, and Figure 5 is a schematic diagram showing the measurement targets of each distance sensor 83X1, 83Y1, 83Y2, 83Z1, 83Z2, and 83Z3 when the measurement unit 80 measures the unit to be measured 90. The solid and dashed arrows shown in Figures 4 and 5 indicate the laser output direction of each distance sensor 83X1, 83Y1, 83Y2, 83Z1, 83Z2, and 83Z3.

[0038] In the overhead transport vehicle system S of this embodiment, when acquiring the state of the overhead transport vehicle 1, the unit to be measured 90 is mounted on the overhead transport vehicle 1, and the measurement unit 80 is mounted on the load port device 300. That is, the unit to be measured 90 is used by being gripped by a pair of grippers 8, 8, and the measurement unit 80 is used by being placed on the upper surface 302 of the load port device 300. The overhead transport vehicle 1 stops at a predetermined position on the track 200, the holding unit 7 is lowered by a predetermined distance, and the state of the overhead transport vehicle 1 is acquired when the unit to be measured 90 is above the load port device 300 and separated from the measurement unit 80.

[0039] As shown in Figures 4 and 6, the measuring unit 80 comprises a main body 81, a plurality of distance sensors 83X1, 83Y1, 83Y2, 83Z1, 83Z2, and 83Z3, a mounting portion 84, a support portion 85, and a guide portion 86. The main body 81 is a flat plate-shaped member that supports the mounting portion 84 and the guide portion 86. The main body 81 is mounted, for example, on the upper surface 302 of the load port device 300 in a horizontal position (see Figure 3). Although not shown, the main body 81 is equipped with a unit controller that performs various electrical processing in the measuring unit 80.

[0040] Each of the distance sensors 83X1, 83Y1, 83Y2, 83Z1, 83Z2, and 83Z3 is, for example, a laser distance sensor and is mounted on the mounting part 84. Distance sensor 83X1 measures the distance to an object by emitting laser light inward from the main body 81 along the X-axis. Distance sensors 83Y1 and 83Y2 measure the distance to an object by emitting laser light inward from the main body 81 along the Y-axis. Distance sensors 83Z1, 83Z2, and 83Z3 measure the distance to an object by emitting laser light upward from the Z-axis.

[0041] The distance sensors 83Z1, 83Z2, and 83Z3 are mounted on the upper surface 302 of the load port device 300, which is a measurement position below the lifting range of the holding unit 7. The main body portion 81 attached to the upper surface 302 has a plurality of openings 87 (or notches) formed therein, for example, corresponding to the number of distance sensors 83Z1, 83Z2, and 83Z3. The top plate 85a of the support portion 85 also has a notch or opening 85b formed therein. The laser beam emission portion of each of the distance sensors 83Z1, 83Z2, and 83Z3 faces the opening 87. The laser beam emitted from the distance sensors 83Z1, 83Z2, and 83Z3 travels upward through the opening 87 and the notch or opening 85b. The distance sensors 83Z1, 83Z2, and 83Z3 are positioned lower than, for example, the upper surface 302 of the load port device 300, but the measurement unit 80 ensures that the path of each laser beam moving in the Z direction is secured. In particular, in this embodiment, the lifting range of the holding unit 7 (see height or total stroke H shown in Figure 8) is long, approximately 6 m or more and less than 10 m. Laser distance sensors having a predetermined or higher measurement accuracy are used as the distance sensors 83Z1, 83Z2, and 83Z3.

[0042] The attachment portion 84 is a portion to which the distance sensors 83X1, 83Y1, 83Y2, 83Z1, 83Z2, and 83Z3 are attached, and is erected on the main body portion 81. The support portion 85 is a portion that supports the measurement unit 90, and is erected on the main body portion 81. The guide portion 86 is a portion that guides the measurement unit 90 to be positioned at a predetermined position when the measurement unit 90 is supported by the support portion 85. The guide portion 86 is erected on the main body portion 81.

[0043] The measurement unit 90 includes a flange 91, a base plate 92, a plurality of target plates 93, 94, and 95, and legs 97. The flange 91 is a portion provided to be grippable by the gripper 8. The base plate 92 is connected to the flange 91, and a plurality of target plates 93, 94, and 95 are erected thereon. The base plate 92 and the plurality of target plates 93, 94, and 95 are portions that form a measurement target surface by the distance sensors 83X1, 83Y1, 83Y2, 83Z1, 83Z2, and 83Z3.

[0044] Each of the target plates 93, 94, and 95 is fixed at a predetermined position on the base plate 92. The surface 93a of the target plate 93 facing the distance sensor 83X1 is a surface perpendicular to the X-axis direction, and has a predetermined positional relationship with the reference position of the load port device 300 (the center position of the upper surface 302 which is the placement surface). The surface 94a of the target plate 94 facing the distance sensor 83Y1 and the surface 95a of the target plate 95 facing the distance sensor 83Y2 are surfaces perpendicular to the Y-axis direction, and have a predetermined positional relationship with the reference position of the load port device 300. The legs 97 are provided at the lower portions of the target plates 93, 94, and 95 respectively, and contact the main body portion 81 of the measurement unit 80 when the measurement unit 80 supports the measurement unit 90.

[0045] As a result, the unit controller 82 of the measurement unit 80 can acquire the measured distances from each distance sensor. Based on each measured distance, the unit controller can calculate the actual position (X coordinate, Y coordinate, Z coordinate) of the gripper 8 with respect to the reference position of the load port device 300 as the origin, and can calculate the angle (tilt) of the holding unit 7 with respect to the horizontal plane using distance sensors 83Z1, 83Z2, and 83Z3.

[0046] As shown in Figure 6, the overhead transport vehicle 1 includes the linear motion mechanism 67 described above, a storage unit 11 for storing information related to measurement results and correction results, a direct communication unit 12 for communicating with the port controller 310, and the communication display unit 15. The load port device 300 includes a port communication unit 312 for communicating with the direct communication unit 12, the various distance sensors described above, and a display unit 303. The angle of the holding unit 7 may be calculated by the unit controller of the measurement unit 80, or by the port controller 310 of the load port device 300. In the following description, we will explain the case in which the port controller 310 of the load port device 300 calculates the angle of the holding unit 7.

[0047] Next, with reference to Figures 7 to 9, the angle correction method for the holding unit 7 by the transport controller 9 and the port controller 310 will be described. In a series of control operations, the transport controller 9 and the port controller 310 communicate with each other and perform angle measurement and angle correction in cooperation (synchronized timing). Angle correction is performed by changing or adjusting the set values ​​of the operating amount of the linear motion mechanism 67. During the following teaching operations and measurements, the transport controller 9 controls the lifting drive unit 6 and the holding unit 7 so that the holding unit 7 grips the unit to be measured 90 (on the load port device 300). When not performing teaching operations or measurements, the unit to be measured 90 is placed (returned) on the load port device 300.

[0048] First, the carrier controller 9 positions the ceiling carrier 1 and performs a rough teaching operation (step S11). For example, at a position slightly higher than the lowest position LL shown in FIG. 1 (the position where the belt B is wound up), the carrier controller 9 performs a rough teaching operation. At this time, the rough angle teaching operation is also performed by the portable device 400 or other remote control. This teaching operation may be performed by the operation monitor on the display unit 303 of the load port device 300. Subsequently, the carrier controller 9 shifts to the machine difference measurement mode at the lowest position LL through the operation of the remote control (step S12). At the same time, the port controller 310 receives a measurement start operation through the operation of the remote control (step S21). On the other hand, the carrier controller 9 lowers the holding unit 7 (step S13). The carrier controller 9 stops the holding unit 7 at the lowest position LL.

[0049] The port controller 310 measures the machine difference and inclination of the ceiling carrier 1 at the lowest position LL (step S22). Here, the "machine difference" is the actual position of the gripper 8 (individual differences in the X coordinate, Y coordinate, and Z coordinate) with the reference position of the load port device 300 in the ceiling carrier 1 as the origin. The "inclination" is the angle (inclination) of the holding unit 7 with respect to the horizontal plane in the ceiling carrier 1 and at the lowest position LL. The port controller 310 feeds back various information related to the stroke amount (that is, in this case, the lowest position LL), inclination, and machine difference to the carrier controller 9 (step S23). The information related to the inclination corresponds to the "measurement result of the angle". The carrier controller 9 places the measurement unit 90 on the main body 81 of the load port device 300 (see FIG. 4) and corrects the inclination and machine difference by the linear motion mechanism 67 (step S14). In this step S14, since the horizontal measurement sensors (distance sensors 83X1, 83Y1, 83Y2) also detect the measurement unit 90, correction of the horizontal axes (X axis, Y axis, and θ axis) is also possible. The port controller 310 measures the machine difference and inclination of the ceiling carrier 1 again at the lowest position LL, similar to step S22 (step S24).

[0050] The port controller 310 then determines whether the measurement results of the machine error and tilt obtained in step S24 fall within the respective allowable values ​​that have been stored in advance (step S25). If it is determined that the measurement results of the machine error and tilt do not fall within the respective allowable values, the port controller 310 and the transport vehicle controller 9 may repeat the processes in steps S14, S24, and S25. If it is determined that the measurement results of the machine error and tilt fall within the respective allowable values, the port controller 310 instructs the transport vehicle controller 9 to move the holding unit 7 to the next stroke (i.e., height level) (step S26).

[0051] Then, as shown in Figure 9, the transport controller 9 moves the holding unit 7 to the intermediate position LM, which is the next stroke (i.e., height level), and stops it (step S15). The transport controller 9 corrects the stroke amount and the tilt amount (step S16). The transport controller 9 estimates the amount the holding unit 7 is extended based on the rotational speed of the drive motor 63A. When the transport controller 9 grasps the actual amount of extension using external vertical (Z-direction) measurement sensors (distance sensors 83Z1, 83Z2, 83Z3), it recognizes the difference between the estimated amount and the actual amount of extension, and uses that difference to correct the stroke amount and tilt amount using the drive motor 63A and the linear motion mechanism 67. When the holding unit 7 is at the intermediate position LM, the unit to be measured 90 is at a high position and is far from the measurement unit 80 (load port device 300) in the Z direction, so the horizontal measurement sensors cannot be used. The transport vehicle controller 9 uses the estimated values ​​that it calculates and stores internally, along with the measurement results in the Z direction from an external sensor, to perform the above correction in step S16 at the intermediate position LM.

[0052] Following the measurement and correction process in step S16, a remeasurement is performed at the intermediate position LM, and a determination is made as in steps S24 and S25, to determine whether the value falls within the acceptable range.

[0053] The port controller 310 stores how many points within the lifting range (height or total stroke H shown in Figure 8) of the holding unit 7 in the overhead transport vehicle 1 should perform steps S26, S15, S16, and the re-measurement and tolerance value determination described above. The port controller 310 determines whether these processes have been performed for all strokes (height levels) and makes a termination determination based on this determination (step S27). If the port controller 310 determines that termination is possible, it saves all measurement data to the storage unit 11 (step S28).

[0054] Through the above series of processes, the machine error at the lowest position LL is measured and corrected, the angle at the lowest position LL is measured and corrected, and the angle at each of the multiple intermediate positions LM is measured and corrected. An angle correction value corresponding to each stroke (height level) is generated and stored by the transport vehicle controller 9. The number of height level points to be measured in each overhead transport vehicle 1 varies depending on the total stroke H, but is, for example, between 3 and 10 points.

[0055] According to the overhead transport vehicle system S and angle correction method of this embodiment, the angle of the holding unit 7 with respect to the horizontal plane at each of the multiple height levels is measured by a single load port device 300. Therefore, complexity of the configuration is prevented. Since common sensors (distance sensors 83Z1, 83Z2, 83Z3, etc.) are used for measurements at multiple height levels, calibration and other adjustment work can be performed with a single device, and maintaining measurement accuracy is easy.

[0056] The load port device 300 includes at least three laser distance sensors (distance sensors 83Z1, 83Z2, 83Z3) located at measurement positions below the lifting range of the holding unit 7. By using at least three laser distance sensors (distance sensors 83Z1, 83Z2, 83Z3), the angle of the holding unit 7 with respect to the horizontal plane at each of the multiple height levels can be easily measured.

[0057] The transport vehicle controller 9 stops the lifting drive unit 6 at each height level, controls the linear motion mechanism 67 to correct the angle of the holding unit 7, and then determines whether the angle measurement result obtained again by the load port device 300 at the height level where the vehicle is stopped falls within an acceptable range. Based on this determination, it is possible to decide whether or not to move to the next height level. Measurement and verification at multiple height levels can be carried out quickly.

[0058] In the overhead transport vehicle system S described above, the transport vehicle controller 9 may, when it determines that the angle measurement result obtained again by the angle measuring device (load port device 300) is within an acceptable range, control the lifting drive unit 6 to move the holding unit 7 to another height level, and control the linear motion mechanism 67 based on the angle measurement result at that other height level. In this case, the angle of the holding unit 7 at each height level can be corrected more accurately.

[0059] In the overhead transport system S described above, the item is a reticle pod that houses a reticle, and the lifting range of the holding unit 7 is at least 6 m. In the holding unit 7 that holds the reticle pod, the lifting range (i.e., the overall stroke H) tends to be long. Even when the lifting range is 6 m or more, the angle of the holding unit 7 can be appropriately corrected by measuring the angle at, for example, three or more height levels and making corrections as necessary.

[0060] Although embodiments of the present disclosure have been described above, the present invention is not limited to the above embodiments. For example, the system configuration is not limited to the configuration shown in Figure 1. For example, as shown in Figure 10, the load port device 300 and the transport vehicle controller 9 may perform angle measurement and correction via the maintenance controller 100 and the higher-level controller 5. In this case, the timing of the angle measurement and angle correction operations is appropriately determined (scheduled) by the maintenance controller 100. The higher-level controller 5 then places the overhead transport vehicles 1 on the load port device 300 according to the schedule. The load port device 300 feeds the measurement results back to the overhead transport vehicles 1. Each overhead transport vehicle 1 rewrites its machine error and returns to operation. If it is determined that the machine error is too large, the abnormality is reported at the time of feedback.

[0061] Simultaneously with the above, machine difference data and angle data are notified to the maintenance controller 100. The maintenance controller 100 stores the received machine difference data and angle data in the data server 600. This data is displayed and visualized on the display unit of the maintenance viewer 500. Depending on the degree of change in the data (for example, if the degree of change is too large), an abnormality may be notified.

[0062] Figure 11 shows an example of the display on the maintenance viewer 500. For example, the maintenance controller 100 and the data server 600 store the angle measurement results and the angle correction history by the linear motion mechanism 67 for each height level for each overhead transport vehicle 1, and the measurement results and correction history can be displayed on the display unit 510 of the maintenance viewer 500 for each overhead transport vehicle 1. For example, the angle screen 520 of the display unit 510 displays a unique number that identifies the overhead transport vehicle 1, along with the corresponding machine error data and angle data, along with the date. The history screen 530 of the display unit 510 also displays a graph of the unique number that identifies the overhead transport vehicle 1 and the corresponding measurement history (and / or correction history). The horizontal axis of the graph may be the date. This allows administrators (operators, etc.) to easily check the measurement results and correction history for each overhead transport vehicle 1.

[0063] The angle measuring device is not limited to the load port device 300, and may be suspended in the air, such as a storage device (buffer) suspended from the ceiling or a track.

[0064] The load port device 300 may include at least three laser distance sensors provided on the holding unit 7 and directed downward. In this case, the laser distance sensors irradiate laser light toward a predetermined horizontal plane below (for example, the mounting surface of the load port).

[0065] Another angle measuring device equipped with sensors other than a laser distance sensor may be provided.

[0066] The item may be a Front Opening Unified Pod (FOUP) containing multiple wafers.

[0067] 1...Overhead transport vehicle, 6...Lifting drive unit (lifting device), 7...Holding unit, 9...Transport vehicle controller, 67...Linear motion mechanism (correction mechanism), 300...Load port device (angle measuring device), 310...Port controller, 83Z1, 83Z2, 83Z3...Distance sensors (laser distance sensors), S...Overhead transport vehicle system.

Claims

1. An overhead transport vehicle system comprising: a holding unit for holding articles; a lifting device for raising and lowering the holding unit; and a correction mechanism controlled by a controller for correcting the angle of the holding unit, wherein the system includes one angle measuring device for measuring the angle of the holding unit with respect to the horizontal plane at each of a plurality of height levels within the lifting range of the holding unit, and the controller stores the measurement results of the plurality of angles obtained by the angle measuring device and controls the correction mechanism based on the measurement results of the angles at each of the height levels.

2. The overhead transport vehicle system according to claim 1, wherein the angle measuring device includes a measuring position below the lifting range of the holding unit, or at least three laser distance sensors provided on the holding unit.

3. The overhead transport vehicle system according to claim 1 or 2, wherein the controller stops the lifting device at each of the height levels, controls the correction mechanism to correct the angle of the holding unit, and then determines whether the angle measurement result obtained again by the angle measuring device at the height level where the device is stopped falls within an acceptable range.

4. The overhead transport vehicle system according to claim 3, wherein the controller, when it determines that the angle measurement result obtained again by the angle measuring device is within an acceptable range, controls the lifting device to move the holding unit to another height level, and controls the correction mechanism based on the angle measurement result at that other height level.

5. The overhead transport vehicle system according to claim 1 or 2, wherein the controller stores the measurement results of the angle at each of the height levels and the correction history of the angle by the correction mechanism for each overhead transport vehicle, and the measurement results and the correction history can be displayed on a display unit for each overhead transport vehicle.

6. An angle correction method for an overhead transport vehicle system comprising a holding unit for holding articles, a lifting device for raising and lowering the holding unit, and a correction mechanism controlled by a controller for correcting the angle of the holding unit, the method comprising: measuring the angle of the holding unit with respect to the horizontal plane at each of a plurality of height levels within the lifting range of the holding unit using one angle measuring device; storing the measurement results of the plurality of angles obtained by the angle measuring device; and correcting the angle of the holding unit based on the measurement results of the angles at each of the height levels.

Images