Overhead transport vehicle and method for determining irradiation direction of sensor

Abstract

The invention relates to an overhead transport vehicle and a method for determining the irradiation direction of a sensor. The overhead transport vehicle is provided with a main body part, a lifting platform, a lifting driving part, a sensor, an irradiation direction changing mechanism and a control part. A reflecting plate is arranged on the lifting platform. The control unit is capable of executing teaching processing for acquiring the irradiation direction data and irradiation direction changing processing for changing the irradiation direction by the irradiation direction changing mechanism. The teaching process includes: a first process of irradiating detection light from the sensor and detecting whether reflected light reflected by the reflecting plate is received by the sensor; a second process in which the irradiation direction is changed by the irradiation direction changing mechanism, and the first process is performed a plurality of times so as to detect reflected light on one end side and the other end side of the reflecting plate; and a third process for obtaining irradiation direction data on the basis of the irradiation direction when the reflected light is detected by the second process.

Description

Technical Field

[0001] One aspect of the present invention relates to an overhead travelling vehicle and a method for determining an illumination direction of a sensor. Background Art

[0002] For example, Patent Document 1 describes an overhead transport vehicle comprising a main body, a lift platform capable of being raised and lowered relative to the main body, a lift drive unit for raising and lowering the lift platform, and a sensor (a sway detection sensor) disposed on the lift drive unit and emitting detection light. In this overhead transport vehicle, the sensor emits detection light downward, and the sensor receives reflected light (hereinafter referred to as "reflected light") from a reflector disposed on the lift platform.

[0003] Patent Document 1: Japanese Patent No. 6617832

[0004] In an overhead transport vehicle, if the lift drive unit tilts for some reason, the tilt can cause the detection light to leave the lift platform's reflector, potentially preventing the sensor from receiving the reflected light. In this case, for example, even if the lift platform is not actually shaking or is shaking within the permitted range, the sensor may mistakenly detect the platform's shaking. Regarding this point, in the overhead transport vehicle described above, an actuator is used to change the sensor's posture to reduce the influence of the lift drive unit's tilt on the lift platform's shaking detection. However, if the lift drive unit's tilt differs from the assumed value, it cannot be properly corrected, leaving room for improvement. Summary of the Invention

[0005] An object of one aspect of the present invention is to provide an overhead travelling vehicle that accurately corrects the irradiation direction of detection light relative to an unexpected tilt of a sensor and prevents erroneous detection.

[0006] (1) An overhead transport vehicle according to one aspect of the present invention comprises: a main body; a lifting platform capable of being raised and lowered relative to the main body; a lifting drive unit that raises and lowers the lifting platform; a sensor provided in the lifting drive unit for irradiating detection light toward a point below and receiving reflected light of the detection light; an irradiation direction changing mechanism capable of changing the irradiation direction of the detection light irradiated by the sensor; and a control unit that controls at least the operation of the sensor and the irradiation direction changing mechanism, wherein a reflecting plate capable of reflecting the detection light of the sensor is provided on the lifting platform, and the control unit is capable of performing the following processing: a teaching processing for obtaining irradiation direction data related to the irradiation direction; and an irradiation direction changing processing for changing the irradiation direction by the irradiation direction changing mechanism based on the irradiation direction data obtained by the teaching processing, the teaching processing including: a first processing for irradiating detection light from the sensor and detecting whether the sensor receives reflected light reflected by the reflecting plate; a second processing for changing the irradiation direction by the irradiation direction changing mechanism, and performing the first processing multiple times so that reflected light is detected at least once on each of one end side and the other end side of the reflecting plate; and a third processing for obtaining irradiation direction data based on the irradiation direction when the reflected light is detected by the second processing.

[0007] With this overhead travelling vehicle, even a sensor designed to detect a single point can obtain irradiation direction data based on reflected light from two or more points. Therefore, regardless of whether the lift drive unit is tilted, the sensor angle can be corrected to direct the detection light toward a position close to the center of the reflector. Consequently, even if the lift drive unit's tilt differs from the assumed tilt, false detections of platform wobbles can be reduced.

[0008] (2) In the overhead transport vehicle described in (1) above, the second processing may be such that the detected light traces a straight line with the outside of the reflector being the irradiation start position and the irradiation end position, and the irradiation direction changing mechanism changes the irradiation direction, and the first processing is performed at a constant interval. The third processing may also be such that, based on the result of the second processing, the center position of the irradiation direction when the reflected light is first detected and the irradiation direction when the reflected light is last detected is set as the irradiation direction data. In this case, a position closer to the center of the reflector can be obtained as the irradiation direction data, and false detections can be further reduced.

[0009] (3) In the overhead transport vehicle described in (1) or (2) above, the irradiation direction changing mechanism may include an actuator capable of changing the angle of the sensor relative to the lifting drive unit. In this case, the actuator can freely change the irradiation direction of the detection light irradiated by the sensor (hereinafter referred to as "irradiation direction"), so that the irradiation direction data can be accurately reproduced.

[0010] (4) In the overhead transport vehicle described in (3) above, the actuator may be a servo motor. In this case, the servo motor can be used to adjust the angle of the irradiation direction more finely, and the detection light can be irradiated toward the center of the reflector more reliably.

[0011] (5) The overhead transport vehicle described in any one of (1) to (4) above may also include a lateral extension mechanism that moves the elevating drive unit laterally relative to the main body, wherein the teaching process may be performed while the elevating drive unit is moved laterally by the lateral extension mechanism, and the irradiation direction change process may be performed while the elevating drive unit is moved or has been moved laterally by the lateral extension mechanism. Thus, the irradiation direction can be changed when the elevating drive unit is moved by the lateral extension mechanism.

[0012] (6) The overhead transport vehicle described in any one of (1) to (4) above may also include a lateral extension mechanism that moves the lifting drive unit laterally relative to the main body, the teaching process may also be performed in each state where the lifting drive unit is moved laterally by a first to Nth movement amount (N is an integer greater than or equal to 2) by the lateral extension mechanism, and the irradiation direction changing process may also be performed based on the irradiation direction data corresponding to any one of the first to Nth movement amounts when the lifting drive unit is moved laterally or by any one of the first to Nth movement amounts by the lateral extension mechanism, and the irradiation direction is changed by the irradiation direction changing mechanism. Thus, the irradiation direction can be changed according to the amount of movement of the lifting drive unit laterally by the lateral extension mechanism.

[0013] (7) The overhead transport vehicle described in any one of (1) to (6) above may be a transport vehicle capable of transferring articles to a plurality of loading sections, the teaching process may be performed in each case of transferring articles to the plurality of loading sections, and the irradiation direction changing process may be performed by changing the irradiation direction by the irradiation direction changing mechanism based on the irradiation direction data corresponding to any of the plurality of loading sections when an article is transferred to any of the plurality of loading sections. Thus, the irradiation direction can be changed according to the loading section to which the article is transferred.

[0014] (8) An aspect of the present invention is a method for determining the irradiation direction of a sensor, in an overhead transport vehicle having a main body, a lifting platform capable of being raised and lowered relative to the main body, a lifting drive unit for raising and lowering the lifting platform, and a sensor provided in the lifting drive unit and detecting the shaking of the lifting platform, the method comprising the following steps: a first step of irradiating the detection light from the sensor and detecting whether the sensor receives reflected light reflected from a reflective plate arranged on the lifting platform; a second step of changing the irradiation direction by an irradiation direction changing mechanism and performing the first step multiple times so that the reflected light is detected at least once on each of one end side and the other end side of the reflective plate; and a third step of obtaining irradiation direction data related to the irradiation direction based on the irradiation direction when the reflected light is detected by the second step.

[0015] This sensor's illumination direction determination method allows even a sensor designed to detect a single point to obtain illumination direction data based on reflected light from two or more points. Therefore, regardless of whether the lift drive unit is tilted, the sensor angle can be corrected to direct the detection light toward a position close to the center of the reflector. Consequently, even if the lift drive unit's tilt differs from the assumed tilt, false detections of platform movement can be reduced.

[0016] According to one aspect of the present invention, the irradiation direction of the detection light can be accurately corrected with respect to an unexpected tilt of the sensor, and erroneous detection can be prevented. BRIEF DESCRIPTION OF THE DRAWINGS

[0017] Figure 1 It is a side view of the overhead travelling vehicle showing one embodiment.

[0018] Figure 2 Yes Figure 1 Front view of the overhead conveyor truck.

[0019] Figure 3 It is a side view showing the shake detection sensor.

[0020] Figure 4 (a) is a front view illustrating the change of the irradiation direction by the servo motor. Figure 4 (b) is a front view illustrating the change of the irradiation direction by the servo motor. Figure 4 (c) is a front view illustrating the change of the irradiation direction by the servo motor. Figure 4 (d) is a front view illustrating the change of the irradiation direction by the servo motor. Figure 4 (e) is a front view illustrating the change of the irradiation direction by the servo motor. Figure 4 (f) is a front view illustrating the change of the irradiation direction by the servo motor. Figure 4(g) is a front view illustrating the change of the irradiation direction by the servo motor.

[0021] Figure 5 (a) is a front view illustrating the teaching process. Figure 5 (b) is an explanation Figure 5 (a) Continuation of the front view. Figure 5 (c) is a description Figure 5 (b) Subsequent main view.

[0022] Figure 6 (a) is a description Figure 5 (c) Subsequent main view. Figure 6 (b) is an explanation Figure 6 (a) Subsequent main view.

[0023] Figure 7 (a) is a front view showing an example of transferring articles by an overhead travelling vehicle. Figure 7 (b) is a front view showing another example of transferring articles by an overhead travelling vehicle.

[0024] Figure 8 This is a diagram showing a data table including irradiation direction data for each of a plurality of lateral shift amounts.

[0025] Figure 9 This is a diagram showing a data table including irradiation direction data for each of a plurality of load ports.

[0026] Figure 10 It is a side view of a fluctuation detection sensor showing a modified example. DETAILED DESCRIPTION

[0027] Hereinafter, the embodiments will be described in detail with reference to the accompanying drawings. In the description of the drawings, the same or corresponding components are denoted by the same reference numerals, and redundant descriptions will be omitted.

[0028] like Figure 1 As shown, an overhead transport vehicle 1 of the embodiment travels along a track 20 installed near the ceiling of a clean room for manufacturing semiconductor equipment. The track 20 forms the travel path of the overhead transport vehicle 1. The overhead transport vehicle 1 is a transport vehicle capable of transporting an article 200 and transferring the article 200 to a loading port 300. The article 200 is, for example, a FOUP (Front Opening Unified Pod) that stores a plurality of semiconductor wafers. The loading port 300 is, for example, a loading portion provided in a processing device that performs various processes on the semiconductor wafers. The article 200 and the loading port 300 are not particularly limited.

[0029] In the following description, the terms "up" and "down" correspond to the vertically upper and lower directions, respectively. The term "front" corresponds to the front side in the travel direction of the overhead transport vehicle 1, and the term "rear" corresponds to the rear side in the travel direction of the overhead transport vehicle 1. The X direction corresponds to the front-to-back direction, the Z direction corresponds to the up-to-down direction, and the X direction corresponds to the left-to-right direction (a direction perpendicular to both the front-to-back direction and the up-to-down direction).

[0030] The overhead transport vehicle 1 includes a frame unit 2, a travel unit 3, a traverse unit 4, a theta unit 5, a lift drive unit 6, a lift platform 7, and a transport vehicle controller 8. The frame unit 2 includes a center frame 15, a front frame 16, and a rear frame 17. The frame unit 2 constitutes a main body. The front frame 16 extends downward from the front end of the center frame 15. The rear frame 17 extends downward from the rear end of the center frame 15.

[0031] The travel unit 3 is arranged on the upper side of the center frame 15. The travel unit 3 travels along the track 20 by, for example, receiving power in a non-contact manner from a high-frequency current line laid along the track 20. The transverse unit 4 is arranged on the lower side of the center frame 15. The transverse unit 4 moves the θ unit 5, the lifting drive unit 6, and the lifting platform 7 relative to the frame unit 2 in the Y direction (laterally and transversely in the travel direction of the overhead transport vehicle 1). The transverse unit 4 constitutes a transverse extension mechanism. The θ unit 5 is arranged on the lower side of the transverse unit 4. The θ unit 5 rotates the lifting drive unit 6 and the lifting platform 7 in a horizontal plane.

[0032] The lifting drive unit 6 is disposed below the θ unit 5. The lifting drive unit 6 raises and lowers the lifting platform 7 in the Z direction by unwinding and reeling in a plurality of suspension components B, such as belts, connected to the lifting platform 7. The suspension components B are flexible. The lifting drive unit 6 constitutes a lifting drive unit. The lifting platform 7 is disposed below the lifting drive unit 6. The lifting platform 7 is configured to be able to be raised and lowered relative to the frame unit 2 by the lifting drive unit 6. The lifting platform 7 has a holding portion 12, such as a pair of clamps, that can be opened and closed in the horizontal direction. The lifting platform 7 holds the flange 201 of the article 200 using the pair of holding portions 12.

[0033] The transport vehicle controller 8 is configured on the center frame 15. The transport vehicle controller 8 is an electronic control unit composed of a CPU (Central Processing Unit), a ROM (Read only memory), and a RAM (Random access memory). The transport vehicle controller 8 is a control unit that controls various parts of the overhead transport vehicle 1. The transport vehicle controller 8 can be composed of multiple electronic control units. When composed of multiple electronic control units, they can also be connected via a communication network such as the Internet or an intranet, thereby logically forming a unit. The transport vehicle controller 8 can also be configured on the front frame 16, etc.

[0034] The overhead transport vehicle 1 constructed as described above operates as follows as an example. When an article 200 is transferred from the loading port 300 to the overhead transport vehicle 1, the overhead transport vehicle 1 without holding the article 200 stops at a predetermined position above the loading port 300. When the position of the lifting platform 7 lowered at the stop position deviates from the specified position for the loading port 300 (the article 200 loaded on the loading port 300), the horizontal position and horizontal angle of the lifting platform 7 are adjusted by driving the lateral unit 4 and the θ unit 5. Then, the lifting drive unit 6 lowers the lifting platform 7, and the holding portion 12 of the lifting platform 7 holds the flange 201 of the article 200 loaded on the loading port 300. Then, the lifting drive unit 6 raises the lifting platform 7 to the rising end and arranges the article 200 between the front frame 16 and the rear frame 17. Then, the overhead transport vehicle 1 holding the article 200 starts to move.

[0035] On the other hand, when transferring the article 200 from the overhead transport vehicle 1 to the loading port 300, the overhead transport vehicle 1 holding the article 200 stops at a predetermined position above the loading port 300. When the position of the lifting platform 7 (article 200) that has been lowered at the stopped position deviates from the specified position relative to the loading port 300, the horizontal position and horizontal angle of the lifting platform 7 are adjusted by driving the lateral unit 4 and the θ unit 5. Next, the lifting drive unit 6 lowers the lifting platform 7, places the article 200 on the loading port 300, and causes the holding portion 12 of the lifting platform 7 to release the flange 201 of the article 200. Next, the lifting drive unit 6 raises the lifting platform 7 to the rising end. Next, the overhead transport vehicle 1 that does not hold the article 200 starts to travel.

[0036] like Figure 1 、 Figure 2 as well as Figure 3As shown, the overhead transport vehicle 1 includes a shaking detection sensor 10, a reflector 11, a servo motor 30, and a servo motor controller 32. The shaking detection sensor 10 is a sensor provided in the lifting drive unit 6. The shaking detection sensor 10 is not particularly limited, but is, for example, a laser rangefinder. The shaking detection sensor 10 irradiates detection light A toward a point below and receives reflected light A0 of the detection light A. Specifically, the shaking detection sensor 10 irradiates detection light A such as laser (light) toward the reflector 11 below and detects reflected light A0 which is return light when the detection light A is reflected by the reflector 11. The shaking detection sensor 10 is connected to the transport vehicle controller 8.

[0037] The reflector 11 is provided on the lifting platform 7. As an example, the reflector 11 is provided in the center of the upper portion of the lifting platform 7. The reflector 11 is capable of reflecting the detection light A of the shaking detection sensor 10. The reflector 11 is arranged with its reflective surface facing upward, and is capable of reflecting the detection light A from above upward. When the lifting drive unit 6 is in a horizontal state, the reflector 11 is arranged directly below the shaking detection sensor 10. There is no particular limitation on the reflector 11, and various reflectors can be used.

[0038] In the overhead transport vehicle 1, when the lift platform 7 is not shaking, the shaking detection sensor 10 receives the return light from the reflector 11, thereby being able to detect that there is no shaking of the lift platform 7. On the other hand, in the overhead transport vehicle 1, when the lift platform 7 is shaking, for example, the laser L from the shaking detection sensor 10 is not projected onto (does not hit) the reflector 11, and the shaking detection sensor 10 does not receive the reflected light A0 from the reflector 11. Thus, it is possible to detect that there is shaking of the lift platform 7. The shaking of the lift platform 7 corresponds to the movement (swing) of the vibrator having the lifting drive unit 6 as a fulcrum and the suspension component B as an arm.

[0039] The servo motor 30 constitutes an irradiation direction changing mechanism capable of changing the irradiation direction (orientation) of the detection light A irradiated by the sway detection sensor 10. The servo motor 30 is an actuator capable of changing the angle of the sway detection sensor 10 relative to the lifting drive unit 6. The servo motor 30 is provided in the lifting drive unit 6. The servo motor 30 has a rotating shaft 30X with the X direction as the axial direction. The rotating shaft 30X is connected to the sway detection sensor 10. Thus, the servo motor 30 supports the sway detection sensor 10 so as to be rotatable in the rotation direction around the X direction. As a result, by driving the servo motor 30, the irradiation direction of the detection light A from the sway detection sensor 10 is changed (rotated around the X direction) in a manner of moving along the Y direction. The servo motor 30 is not particularly limited, and various well-known servo motors can be used. For example, the servo motor 30 is a small servo motor.

[0040] The servo motor 30 outputs the rotation angle of the rotation shaft 30X to the servo motor controller 32. The servo motor 30 has, for example, an encoder with sufficient resolution and can steplessly change the irradiation direction of the detection light A. In other words, the servo motor 30 does not change the irradiation direction of the detection light A between a limited number of directions, but can freely change the irradiation direction of the detection light A to a desired direction within an arbitrary range. For example, Figure 4 (a)~ Figure 4 As shown in (g), the servo motor 30 can freely change the posture of the shake detection sensor 10 itself in the rotation direction around the X direction, and can freely change the irradiation direction of the detection light A from the shake detection sensor 10 in the Y direction, so the irradiation direction data can be accurately reproduced.

[0041] Furthermore, the irradiation direction of the detection light A may be, for example, a relative direction relative to the lifting drive unit 6, with one side of the circumference around the X-axis being positive and the other side of the circumference around the X-axis being negative. The irradiation direction of the detection light A may not be a direction in the absolute coordinate system. For example, when the inclination of the lifting drive unit 6 relative to the horizontal plane is 0°, the irradiation direction of the detection light A may be a direction with the downward direction of the extension direction being 0°.

[0042] The servo motor controller 32 is an electronic control unit composed of a CPU, ROM, and RAM. The servo motor controller 32 controls the operation of the servo motor 30 based on control instructions from the transport vehicle controller 8, for example. The servo motor controller 32 is capable of transforming the output (PWM (Pulse Width Modulation) output) from the servo motor 30.

[0043] In this embodiment, the transport vehicle controller 8 is capable of executing the following processes: a teaching process for acquiring irradiation direction data related to the irradiation direction of the detection light A from the sway detection sensor 10 (hereinafter referred to as the "irradiation direction"); and an irradiation direction changing process for changing the irradiation direction via the servo motor 30 based on the irradiation direction data acquired through the teaching process. The teaching process and the irradiation direction changing process are executed while the lifting drive unit 6 is being moved laterally by the traverse unit 4.

[0044] The teaching process is performed at least at any one time, such as when the overhead travelling truck 1 is shipped from the factory, during maintenance, before actual operation, and after actual operation. The teaching process includes: a first process (first step) of irradiating detection light A from the shaking detection sensor 10 to detect whether the shaking detection sensor 10 receives reflected light A0 reflected by the reflector 11; a second process (second step) of changing the irradiation direction by the servo motor 30 and performing the first process multiple times so that the reflected light A0 is detected at least once on each of one end side and the other end side of the reflector 11; and a third process (third step) of obtaining irradiation direction data based on the irradiation direction when the reflected light A0 is detected by the second process.

[0045] In the second process, the irradiation direction is changed by the servo motor 30 so that the detection light A draws a straight line with the outside of the reflector 11 as the irradiation start position and the irradiation end position, and the first process is performed at constant intervals. In the second process, the irradiation direction is not changed by scanning the detection light A, but by the action of the servo motor 30, the irradiation direction is changed along with the change in the posture of the shake detection sensor 10. In the second process, the irradiation direction can also be changed by the servo motor 30, for example, every 0.1°. The scale width of the angle of change in the irradiation direction is not particularly limited. In the third process, based on the result of the second process, the irradiation direction when the reflected light A0 is first detected and the center position of the above-mentioned irradiation direction when the reflected light A0 is finally detected are set as irradiation direction data. The irradiation direction data can be defined by the irradiation direction, by the drive amount (rotation angle) of the servo motor 30, or by other parameters.

[0046] As an example, in the teaching process, when the lifting drive unit 6 is moved to the side by the traverse unit 4, Figure 5 As shown in (a), first, the irradiation direction is set to an arbitrary direction by the servo motor 30. The detection light A is irradiated from the shaking detection sensor 10, and it is detected whether the reflected light A0 reflected by the reflector 11 is received by the shaking detection sensor 10 (first processing). Here, the detection light A is not irradiated to the reflector 11 of the lifting platform 7, and the reflected light A0 is not received by the shaking detection sensor 10. The position of the detection light A at this time is the irradiation start position outside the reflector 11. The height position of the lifting platform 7 in the teaching process can also be, for example, the descending position when the article 200 is transferred to the loading port 300 serving as a reference (the position corresponding to the loading port 300), for example, it can also be the lowest position within the lifting range of the lifting platform 7.

[0047] Then, if Figure 5As shown in (b), after the irradiation direction is changed by the servo motor 30, the first process is executed again. Here, the detection light A is irradiated to the reflector 11, and the reflected light A0 is received by the shake detection sensor 10. In this way, in a state where the shake detection sensor 10 does not receive the reflected light A0, after the irradiation direction is changed by the servo motor 30, when the shake detection sensor 10 receives the reflected light A0, the changed irradiation direction (i.e., Figure 5 (b) The information regarding one end of the reflector 11 corresponds to information regarding the position from an area that did not receive reflected light A0 to an area that received reflected light A0. In this case, the end only needs to be located inward of the outer periphery (end) of the reflector 11 (hereinafter, the same shall apply).

[0048] Then, if Figure 5 As shown in (c), after the irradiation direction is further changed by the servo motor 30, the first process is executed again. Here, the detection light A continues to be irradiated to the reflection plate 11, and the reflected light A0 is received by the shaking detection sensor 10. Figure 6 As shown in (a), after the irradiation direction is further changed by the servo motor 30, the first process is executed again. Here, the detection light A continues to be irradiated to the reflection plate 11, and the reflected light A0 is received by the fluctuation detection sensor 10.

[0049] Then, if Figure 6 As shown in (b), after the irradiation direction is further changed by the servo motor 30, the first process is executed again. Here, the detection light A is not irradiated to the reflector 11, and the reflected light A0 is not received by the shake detection sensor 10. In this way, in a state where the reflected light A0 is not received by the shake detection sensor 10, after the irradiation direction is changed by the servo motor 30, when the reflected light A0 is no longer received by the shake detection sensor 10, the irradiation direction before the change (i.e., Figure 6 (a)). The position of the detection light A at this time is the irradiation end position outside the reflector 11. The information about the other end of the reflector 11 corresponds to the information about the position from the area receiving the reflected light A0 to the area not receiving the reflected light A0.

[0050] Next, based on the result of the second process, the center position of the irradiation direction when the reflected light A0 is first detected and the irradiation direction when the reflected light A0 is last detected is set as the irradiation direction data (third process). Specifically, in the third process, the irradiation direction toward one end of the reflector 11 (refer to Figure 5 (b)) is set as θA, and the irradiation direction of the other end of the reflector 11 (refer to Figure 6(a)) is set to θB, the irradiation direction (= (θA + θB) / 2) toward the center position of the reflector 11 is obtained as the irradiation direction data. In other words, based on the position from the area where the reflected light A0 is not received to the area where the reflected light A0 is received, and the position from the area where the reflected light A0 is received to the area where the reflected light A0 is not received, the irradiation direction is determined as the irradiation direction data in such a manner that the detection light A is irradiated toward the center position of the reflector 11 (the middle position between the detected one end and the other end). That is, based on the result of the second processing, the center position of the irradiation direction when the reflected light A0 is first detected (one end) and the irradiation direction when the reflected light A0 is last detected (the other end) is set as the irradiation direction data. In addition, the obtained irradiation direction data is stored in the transport vehicle controller 8.

[0051] For example, Figure 7 As shown in (a), the overhead transport vehicle 1 of this embodiment, without the lift drive unit 6 being moved laterally by the lateral unit 4, uses the servo motor 30 to set the illumination direction as the reference direction, and transfers the above-mentioned article 200. The reference direction is the illumination direction when the detection light A from the vibration detection sensor 10 is illuminated toward the center position of the reflector 11 when the lift drive unit 6 is tilted at 0° relative to the horizontal plane. The reference direction corresponds to, for example, an illumination direction of 0°.

[0052] On the other hand, for example, Figure 7 As shown in (b), while the lift drive unit 6 is being moved sideways by the traverse unit 4, the irradiation direction change process is executed. Based on the irradiation direction data acquired through the teaching process, the servo motor 30 changes the irradiation direction to transfer the article 200. Thus, even if the movement axis of the traverse unit 4 is bent and the lift drive unit 6 tilts after the sideways movement, the detection light A from the vibration detection sensor 10 is directed toward the reflector 11 in accordance with this tilt. The irradiation direction change process can also be executed at any time, at the beginning, during, or after the movement of the lift drive unit 6.

[0053] In this embodiment, the teaching process and the irradiation direction change process are executed in a state where the lifting drive unit 6 is moved sideways by the traverse unit 4. However, the teaching process and the irradiation direction change process may be executed in other states. The teaching process and the irradiation direction change process may also be executed in other states where the lifting drive unit 6 may be tilted.

[0054] As described above, according to the overhead travelling vehicle 1, even a sway detection sensor 10 designed to detect a single point can obtain irradiation direction data based on reflected light A0 from two or more points. Therefore, regardless of whether the lifting drive unit 6 is tilted, the sensor angle can be corrected by irradiating the detection light A toward a position close to the center of the reflector 11. Therefore, even when the tilt of the lifting drive unit 6 differs from the assumed tilt, false detection of sway of the lifting platform 7 can be reduced. Furthermore, for example, the allowable amount of sway can be controlled by the size of the reflector 11. Furthermore, for example, requirements for lateral transfer and long-distance downward transfer can be met.

[0055] In the overhead travelling vehicle 1, the irradiation direction is varied in the Y direction by the servo motor 30 at constant intervals, using detection light A to draw a straight line with the outside of the reflector 11 as the irradiation start and end positions. The irradiation direction data is defined as the center position between the irradiation direction when the reflected light A0 is first detected (at one end) and the irradiation direction when the reflected light A0 is last detected (at the other end). In this case, the irradiation direction data can be obtained as a position closer to the center of the reflector 11, further reducing false detections.

[0056] In the overhead travelling vehicle 1, the servo motor 30 can change the angle of the shake detection sensor 10 relative to the lifting drive unit 6. In this case, the servo motor 30 can freely change the illumination direction, thereby accurately reproducing the illumination direction data. The servo motor 30 can finely adjust the illumination direction (capable of precise angle correction), and the detection light A can be reliably emitted toward the center of the reflector 11.

[0057] In the overhead travelling vehicle 1, the teaching process is executed while the lifting drive unit 6 is moved sideways by the traverse unit 4, and the irradiation direction changing process is executed while the lifting drive unit 6 is moved sideways by the traverse unit 4. Thus, the irradiation direction can be changed while the lifting drive unit 6 is moved by the traverse unit 4.

[0058] The irradiation direction determination method includes the following steps: first, irradiating detection light from the shake detection sensor 10 to detect whether the shake detection sensor 10 receives reflected light A0 from the reflector 11 disposed on the lifting platform 7; second, changing the irradiation direction using the servo motor 30 and performing the first step multiple times so that the reflected light A0 is detected at least once at each of one end and the other end of the reflector 11; and third, determining irradiation direction data based on the irradiation direction when the reflected light A0 is detected in the second step. This irradiation direction determination method accurately corrects the irradiation direction of the detection light A to account for unintended tilt of the shake detection sensor 10, preventing false detections. This improves the accuracy of shake detection on the lifting platform 7.

[0059] Although the embodiment has been described above, one aspect of the present invention is not limited to the above embodiment, and various modifications can be made without departing from the spirit of one aspect of the present invention.

[0060] In the above embodiment, the teaching process may be performed in each state where the lifting drive unit 6 is moved sideways by the first to Nth movement amounts (N is an integer greater than 2) by the lateral unit 4. In this case, for example, Figure 8 As shown, a data table (teaching data) including irradiation direction data for each of a plurality of lateral shift amounts may be acquired. Figure 8 The α in is the reference direction. Figure 8 In the data table, the lateral movement amount is set to 25% scale, but the scale width is not particularly limited and may be, for example, 1%, 2%, 4%, 5%, or 10%. Based on the execution of such teaching processing, in the irradiation direction change processing, even if the lateral unit 4 or the lifting drive unit 6 is moved laterally by any of the first to Nth movement amounts, the irradiation direction can be changed by the servo motor 30 based on the irradiation direction data corresponding to any of the first to Nth movement amounts in the data table.

[0061] In this case, the irradiation direction can be changed based on the amount of lateral movement of the lifting drive unit 6 by the traverse unit 4. This allows for more precise use of the irradiation direction. Furthermore, the irradiation direction data can be set as a variable parameter, for example, with the amount of movement of the lifting drive unit 6 as a variable, centered around a reference angle.

[0062] In the above embodiment, the teaching process may be performed in each case where the article 200 is transferred to a plurality of load ports 300. In this case, for example, Figure 9 As shown in FIG. 1 , a data table including irradiation direction data for each of the plurality of load ports 300 can also be obtained. Figure 9In the data table, the number of load ports 300 is not particularly limited. By executing such a teaching process, when the article 200 is transferred to any of the multiple load ports 300, the irradiation direction can be changed by the servo motor 30 based on the irradiation direction data corresponding to any of the multiple load ports 300 in the data table.

[0063] In this case, the irradiation direction can be changed depending on the load port 300 to which the article 200 is transferred. This allows for more precise selection of irradiation directions. It also enables teaching based on the transfer destination. Furthermore, even if the lift drive unit 6 tilts due to, for example, the track 20 tilting in the left-right direction, the detection light A can still capture the center of the reflector 11. This also allows for transfers that do not involve lateral movement of the lift drive unit 6.

[0064] In addition, regardless of whether the traverse unit 4 moves the lifting drive unit 6, the teaching process and the irradiation direction change process can be performed on each of the plurality of loading ports 300. Alternatively, the teaching process and the irradiation direction change process can be obtained separately depending on whether the traverse unit 4 moves the lifting drive unit 6. Figure 9 In this case, the irradiation direction data corresponding to each load port 300 and corresponding to the presence or absence of lateral movement can be used to change the irradiation direction by the servo motor 30. Alternatively, the irradiation direction data can be obtained separately based on each of the multiple lateral movement amounts performed by the lateral unit 4. Figure 9 The irradiation direction data corresponding to each load port 300 in the irradiation direction data is stored. In this case, the irradiation direction can be changed by the servo motor 30 based on the irradiation direction data corresponding to each load port 300 and corresponding to multiple lateral movement amounts. In the teaching process performed on each of the multiple load ports 300, the height position of the lifting platform 7 may be the lowered position (the position corresponding to each load port 300) when transferring the article 200 to each load port 300.

[0065] In the above embodiment, if Figure 10 As shown, the irradiation direction changing mechanism may further include a servo motor 130 that rotates the servo motor 30 in the rotation direction around the Y axis. In this case, the irradiation direction can be moved in the Y direction by the servo motor 30, and the irradiation direction can be moved in the X direction by the servo motor 130.

[0066] In the above embodiment, the irradiation direction changing mechanism is not limited to the servo motor 30 and may also be another mechanism. Various known actuators may be employed as the irradiation direction changing mechanism. For example, a stepping motor may be used as the irradiation direction changing mechanism. When using a stepping motor, an absolute sensor may be provided, or a claw, etc., may be used for origin restoration.

[0067] In the above embodiment, the shaking of the lift platform 7 is detected by the shaking detection sensor 10. However, the sensor according to one aspect of the present invention is not particularly limited to the shaking detection sensor 10. The sensor according to one aspect of the present invention may be, for example, a so-called overhead sensor that emits directional detection light toward the vicinity of the lift platform 7's descent destination in order to detect foreign objects (obstacles) at the lift platform 7's descent destination.

[0068] The structures of the above-mentioned embodiments and modifications are not limited to the above-mentioned materials and shapes, and various materials and shapes can be applied. The structures of the above-mentioned embodiments or modifications can be arbitrarily applied to the structures of other embodiments or modifications. Within the scope of not departing from the purpose of one embodiment of the present invention, part of the structures of the above-mentioned embodiments or modifications can be appropriately omitted.

[0069] Description of Reference Signs

[0070] 1…Overhead transport vehicle, 2…Frame unit (main body), 4…Horizontal unit (Horizontal extension mechanism), 6…Lifting drive unit (Lifting drive unit), 7…Lifting platform, 8…Transport vehicle controller (Control unit), 10…Shake detection sensor (Sensor), 11…Reflecting plate, 30, 130…Servo motor (Irradiation direction changing mechanism, actuator), 200…Article, 300…Loading port (Loading unit), A…Detection light, A0…Reflected light.

Claims

1. An overhead transport vehicle comprising: Main body; a lifting platform capable of rising and falling relative to the main body; A lifting drive unit, which makes the lifting platform rise and fall; a sensor disposed on the lifting drive portion, irradiating a detection light toward a point below and receiving reflected light of the detection light; an irradiation direction changing mechanism capable of changing the irradiation direction of the detection light irradiated by the sensor; and a control unit that controls at least the operation of the sensor and the irradiation direction changing mechanism; A reflector capable of reflecting the detection light of the sensor is disposed on the lifting platform. The control unit can perform the following processing: Teaching processing to obtain irradiation direction data related to the irradiation direction; and an irradiation direction changing process, in which the irradiation direction is changed by the irradiation direction changing mechanism based on the irradiation direction data acquired by the teaching process; The above teaching process includes: In a first process, the sensor is irradiated with the detection light, and the reflected light reflected by the reflector is detected by the sensor. a second process of changing the irradiation direction by the irradiation direction changing mechanism and performing the first process a plurality of times so that the reflected light is detected at least once each at one end side and the other end side of the reflector; and The third process is to obtain the irradiation direction data based on the irradiation direction when the reflected light is detected in the second process.

2. The overhead transport vehicle according to claim 1, wherein: The second process is to change the irradiation direction by the irradiation direction changing mechanism so that the detection light draws a straight line with the outside of the reflector being the irradiation start position and the irradiation end position, and to perform the first process at a constant interval. The third process sets, based on the result of the second process, a center position between the irradiation direction when the reflected light is first detected and the irradiation direction when the reflected light is last detected as the irradiation direction data.

3. The overhead transport vehicle according to claim 1 or 2, wherein: The irradiation direction changing mechanism includes an actuator capable of changing an angle of the sensor relative to the lifting drive unit.

4. The overhead transport vehicle according to claim 3, wherein: The actuator is a servo motor.

5. The overhead transport vehicle according to claim 1 or 2, comprising: A lateral extension mechanism that moves the lifting drive unit laterally relative to the main body. The teaching process is performed in a state where the lifting drive unit is moved sideways by the lateral extension mechanism. The irradiation direction changing process is performed when the lifting drive unit is moved or has been moved sideways by the lateral extension mechanism.

6. The overhead transport vehicle according to claim 1 or 2, comprising: A lateral extension mechanism that moves the lifting drive unit laterally relative to the main body. The teaching process is performed in each state where the lifting drive unit is moved laterally by the lateral extension mechanism by a first to an Nth movement amount, where N is an integer greater than or equal to 2. The above-mentioned irradiation direction changing process is based on the above-mentioned irradiation direction data corresponding to any one of the above-mentioned first to N-th movement amounts when the above-mentioned lifting drive part is moved sideways or moved by the above-mentioned lateral extension mechanism, and the above-mentioned irradiation direction is changed by the above-mentioned irradiation direction changing mechanism.

7. The overhead transport vehicle according to claim 1 or 2, wherein: The overhead transport vehicle is a transport vehicle capable of transferring articles to a plurality of loading portions. The teaching process is performed in each case of transferring the article to the plurality of placement sections. The irradiation direction changing process changes the irradiation direction by the irradiation direction changing mechanism based on the irradiation direction data corresponding to any of the plurality of placement sections when the article is transferred to any of the plurality of placement sections.

8. A method for determining the illumination direction of a sensor, comprising determining the illumination direction of detection light emitted by the sensor in an overhead transport vehicle comprising a main body, a lift table capable of being raised and lowered relative to the main body, a lift drive unit for raising and lowering the lift table, and a sensor provided in the lift drive unit for detecting sway of the lift table, the method comprising the following steps: In the first step, the sensor emits the detection light and detects whether the sensor receives the reflected light reflected by the reflector disposed on the lifting platform. In a second step, the irradiation direction is changed by an irradiation direction changing mechanism, and the first step is repeated multiple times so that reflected light is detected at least once at each of one end side and the other end side of the reflector; as well as In the third step, irradiation direction data related to the irradiation direction is obtained based on the irradiation direction when the reflected light is detected in the second step.

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