Method for determining the illumination direction of elevated transport vehicles and sensors

Abstract

The elevated transport vehicle of the present invention comprises a main body, a lifting platform, a lifting drive unit, a sensor, an illumination direction changing mechanism, and a control unit. A reflector is disposed on the lifting platform. The control unit can perform: a teaching process, which acquires illumination direction data; and an illumination direction changing process, which changes the illumination direction by means of the illumination direction changing mechanism. The teaching process includes: a first process, which involves irradiating detection light from the sensor and detecting whether the sensor receives reflected light reflected by the reflector; a second process, which changes the illumination direction by means of the illumination direction changing mechanism and performs the first process multiple times to detect reflected light at one end and the other end of the reflector; and a third process, which calculates illumination direction data based on the illumination direction when the reflected light is detected by the second process.

Description

Method for Determining Irradiation Direction of Overhead Conveyor and Sensor One aspect of the present invention relates to a method for determining the irradiation direction of an overhead conveyor and a sensor. For example, Patent Document 1 describes an overhead conveyor that includes: a main body; a lift table that can be lifted relative to the main body; a lift drive unit that lifts the lift table; and a sensor (a sway detection sensor) that is provided in the lift drive unit and irradiates detection light. In such an overhead conveyor, the detection light is irradiated downward from the sensor, and the reflected light of the detection light (hereinafter, also simply referred to as "reflected light") reflected by a reflector provided on the lift table is received by the sensor. [Prior Art Documents] [Patent Documents] Patent Document 1: Japanese Patent No. 6617832 (Problems to be Solved by the Invention) In an overhead conveyor, if the lift drive unit is tilted for some reason, there is a possibility that the detection light is affected by the tilt and deviates from the reflector on the lift table, so that the reflected light cannot be received by the sensor. In this case, for example, even if the lift table does not actually sway, or the sway is within the allowable range, the sway of the lift table may be erroneously detected. In this regard, in the above-mentioned overhead conveyor, although an actuator is used to change the posture of the sensor to reduce the influence of the tilt of the lift drive unit in the detection of the sway of the lift table, when the tilt of the lift drive unit is different from what is expected, it cannot be properly corrected, and there is still room for improvement. An object of one aspect of the present invention is to provide an overhead conveyor that can accurately correct the irradiation direction of the detection light for an unexpectedly tilted sensor, thereby preventing false detection. (Technical Means for Solving the Problem) (1) An elevated transporter according to an aspect of the present invention includes: a main body; a lift table that can be lifted relative to the main body; a lift drive unit that lifts the lift table; a sensor that is provided in the lift drive unit, irradiates detection light toward a point below, and receives the reflected light of the detection light; an irradiation direction changing mechanism that can change the irradiation direction of the detection light irradiated by the sensor; and a control unit that controls at least the operations of the sensor and the irradiation direction changing mechanism; a reflector that can reflect the detection light of the sensor is arranged on the lift table, and the control unit can execute: a teaching process that acquires irradiation direction data regarding the irradiation direction; and an irradiation direction changing process that changes the irradiation direction by the irradiation direction changing mechanism according to the irradiation direction data acquired in the teaching process; the teaching process includes: a first process that irradiates detection light from the sensor and detects whether the sensor receives the reflected light reflected by the reflector; a second process that changes the irradiation direction by the irradiation direction changing mechanism and performs the first process a plurality of times so that the reflected light is detected at least once on each of one end side and the other end side of the reflector; and a third process that obtains the irradiation direction data based on the irradiation direction when the reflected light is detected in the second process. According to this elevated transporter, even for a sensor for detecting one point, irradiation direction data can be obtained based on the reflected light of two or more points. Therefore, regardless of the inclination of the lift drive unit, the sensor angle can be corrected so that the detection light is irradiated toward a position close to the center of the reflector. Therefore, even when the inclination of the lift drive unit is different from what is assumed, it can reduce the false detection of the lift table shaking. (2) In the elevated transporter described in the above (1), it is also possible that the second process changes the irradiation direction by the irradiation direction changing mechanism so that the detection light描绘出a straight line with the outside of the reflector as the irradiation start position and the irradiation end position, and the first process is performed at fixed intervals. The third process takes 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 as the irradiation direction data based on the result of the second process. In this case, it can obtain a position closer to the center of the reflector as the irradiation direction data, thereby further reducing false detection. (3) In the elevated transporter described in the above (1) or (2), the irradiation direction changing mechanism may also include an actuator whose angle relative to the lift drive unit can be changed freely. In this case, since the irradiation direction (hereinafter, also simply referred to as "irradiation direction") of the detection light irradiated by the sensor can be changed freely by the actuator, the irradiation direction data can be accurately reproduced. (4) In the elevated transporter described in the above (3), the actuator may also be a servo motor. In this case, the angle of the irradiation direction can be finely adjusted by the servo motor, so that the detection light can be accurately irradiated toward the center of the reflector. It should be noted that the description "描绘出" in item (4) seems to be an incomplete or incorrect expression in the original text. It may need to be further clarified or corrected in the original Chinese for a more accurate translation. Here, it is tentatively translated as "描绘出" for the purpose of presenting the overall translation content.(5) The overhead transporter described in any one of (1) to (4) above may also be provided with a lateral extension mechanism that enables the lifting drive unit to move laterally relative to the main body unit; the teaching process is executed in a state where the lifting drive unit is moved laterally by the lateral extension mechanism; the irradiation direction change process is executed when the lifting drive unit is moved laterally or has been moved laterally by the lateral extension mechanism. Thereby, it can change the irradiation direction when moving the lifting drive unit by the lateral extension mechanism. (6) The overhead transporter described in any one of (1) to (4) above may also be provided with a lateral extension mechanism that enables the lifting drive unit to move laterally relative to the main body unit; the teaching process is executed in each state where the lifting drive unit has been moved laterally by the lateral extension mechanism by a first to an Nth movement amount (N is an integer of 2 or more); the irradiation direction change process is, when the lifting drive unit is moved laterally or has been moved by any one of the first to the Nth movement amounts by the lateral extension mechanism, based on irradiation direction data corresponding to any one of the first to the Nth movement amounts, the irradiation direction is changed by the irradiation direction change mechanism. Thereby, it can change the irradiation direction according to the movement amount of the lifting drive unit moved laterally by the lateral extension mechanism. (7) The overhead transporter described in any one of (1) to (6) above is a transporter capable of transferring articles to a plurality of placement units, and the teaching process is executed in each case of transferring articles to the plurality of placement units; the irradiation direction change process is, when transferring articles to any one of the plurality of placement units, based on irradiation direction data corresponding to any one of the plurality of placement units, the irradiation direction is changed by the irradiation direction change mechanism. Thereby, it can change the irradiation direction according to the placement unit to which the articles are transferred. (8) A method for determining the irradiation direction of a sensor according to an aspect of the present invention is a method for determining the irradiation direction of detection light irradiated by the sensor in an overhead transporter, and the overhead transporter includes: a main body unit; a lift table that can be lifted relative to the main body unit; a lifting drive unit that lifts the lift table; and a sensor that is provided on the lifting drive unit and detects the sway of the lift table; the method for determining the irradiation direction of the sensor includes: a first step of irradiating detection light from the sensor and detecting whether the sensor receives reflected light reflected by a reflector disposed on the lift table; a second step of changing the irradiation direction by the irradiation direction change mechanism and performing the first step a plurality of times so that reflected light is detected at least once on each of one end side and the other end side of the reflector; and a third step of obtaining irradiation direction data regarding the irradiation direction based on the irradiation direction when the reflected light is detected in the second step. In the method for determining the irradiation direction of the sensor, even for a sensor used to detect one point, irradiation direction data can be obtained based on the reflected light of two or more points. Therefore, regardless of the inclination of the lifting drive unit, the sensor angle can be corrected by irradiating the detection light toward a position closer to the center of the reflection plate. Therefore, even when the inclination of the lifting drive unit is different from what is expected, it can reduce the false detection of the shaking of the lifting table. (Effect compared with the prior art) According to one aspect of the present invention, it can accurately correct the irradiation direction of the detection light for the unexpected inclination of the sensor, thereby preventing false detection. Hereinafter, embodiments will be described in detail with reference to the drawings. In the description of the drawings, the same or equivalent elements are denoted by the same reference numerals, and their repeated description is omitted. As shown in FIG. 1, the overhead transfer vehicle 1 of the embodiment travels along a track 20 laid near the ceiling of a clean room for manufacturing semiconductor devices. The track 20 forms the travel path of the overhead transfer vehicle 1. The overhead transfer vehicle 1 is a transfer vehicle that can transfer an article 200 and transfer the article 200 to and from a loading port 300. The article 200 is, for example, a front opening unified pod (FOUP) that houses a plurality of semiconductor wafers. The loading port 300 is, for example, a placement unit provided on a processing device that performs various processes on semiconductor wafers. The article 200 and the loading port 300 are not particularly limited. In the following description, the terms "upper" and "lower" correspond to the upper and lower directions in the vertical direction, respectively. The term "front" corresponds to the front side in the travel direction of the overhead transfer vehicle 1, and the term "rear" corresponds to the rear side in the travel direction of the overhead transfer vehicle 1. The X direction corresponds to the front-rear direction, the Z direction corresponds to the up-down direction, and the Y direction corresponds to the left-right direction (a direction perpendicular to both the front-rear direction and the up-down direction). The overhead transfer vehicle 1 includes a frame unit 2, a travel unit 3, a lateral unit 4, a θ unit 5, a lifting drive unit 6, a lifting table 7, and a vehicle controller 8. The frame unit 2 has a central frame 15, a front frame 16, and a rear frame 17. The frame unit 2 constitutes the main body part. The front frame 16 extends from the front end of the central frame 15 to the lower side. The rear frame 17 extends from the rear end of the central frame 15 to the lower side. The transfer unit 3 is disposed above the central frame 15. The transfer unit 3 travels along the track 20, for example, by receiving power supply from a high-frequency current line laid along the track 20 in a non-contact manner. The lateral unit 4 is disposed below the central frame 15. The lateral unit 4 moves the θ unit 5, the lifting drive unit 6, and the lifting table 7 relative to the frame unit 2 in the Y direction (the side, the lateral direction of the traveling direction of the overhead carrier 1). The lateral unit 4 constitutes a lateral extension mechanism. The θ unit 5 is disposed below the lateral unit 4. The θ unit 5 rotates the lifting drive unit 6 and the lifting table 7 in the horizontal plane. The lifting drive unit 6 is disposed below the θ unit 5. The lifting drive unit 6 raises and lowers the lifting table 7 along the Z direction by sending out and winding up a plurality of suspension members B such as belts connected to the lifting table 7. The suspension member B has flexibility. The lifting drive unit 6 constitutes a lifting drive portion. The lifting table 7 is disposed below the lifting drive unit 6. The lifting table 7 is provided to be able to be raised and lowered relative to the frame unit 2 by the lifting drive unit 6. The lifting table 7 has a pair of holding portions 12 such as clamps that can be opened and closed in the horizontal direction. The lifting table 7 holds the flange 201 of the article 200 by the pair of holding portions 12. The carrier controller 8 is disposed on the central frame 15. The carrier controller 8 is an electronic control unit composed of a central processing unit (CPU), a read only memory (ROM), a random access memory (RAM), and the like. The carrier controller 8 is a control portion that controls each part of the overhead carrier 1. The carrier controller 8 can be composed of a plurality of electronic control units. In the case of being composed of a plurality of electronic control units, they can be connected via a communication network such as the Internet or an intranet, thereby logically constructing a single unit. The carrier controller 8 can be disposed on the front frame 16 or the like. As an example, the overhead carrier 1 configured as above operates in the following manner. When transferring the article 200 from the loading port 300 to the overhead carrier 1, the overhead carrier 1 that does not hold the article 200 stops at a predetermined position above the loading port 300. When the position of the lifting table 7 that descends to the stop position deviates from a predetermined position relative to the loading port 300 (the article 200 placed on the loading port 300), the horizontal position and the horizontal angle of the lifting table 7 are adjusted by driving the lateral unit 4 and the θ unit 5. Then, the lifting drive unit 6 lowers the lifting table 7, and the holding portion 12 of the lifting table 7 holds the flange 201 of the article 200 placed on the loading port 300. Then, the lifting drive unit 6 raises the lifting table 7 to the upper end, and disposes the article 200 between the front frame 16 and the rear frame 17. Then, the overhead carrier 1 holding the article 200 starts to travel. On the other hand, when transferring the article 200 from the overhead transporter 1 to the loading port 300, the overhead transporter 1 holding the article 200 stops at a predetermined position above the loading port 300. When the position of the lift table 7 (article 200) descending at the stop position deviates from the established position relative to the loading port 300, its horizontal position and horizontal angle of the lift table 7 are adjusted by driving the lateral unit 4 and the θ unit 5. Subsequently, the lift driving unit 6 lowers the lift table 7, places the article 200 on the loading port 300, and the holding portion 12 of the lift table 7 releases the holding of the flange 201 of the article 200. Subsequently, the lift driving unit 6 raises the lift table 7 to the upper end. Subsequently, the overhead transporter 1 not holding the article 200 starts to move. As shown in FIGS. 1, 2, and 3, the overhead transporter 1 includes a sway detection sensor 10, a reflector 11, a servo motor 30, and a servo motor controller 32. The sway detection sensor 10 is a sensor provided in the lift driving unit 6. The sway detection sensor 10 is not particularly limited, and for example, it can be a laser rangefinder. The sway detection sensor 10 irradiates detection light A to a point below, and receives the reflected light A0 of the detection light A. Specifically, the sway detection sensor 10 irradiates the reflector 11 below with detection light A such as laser light (light), and detects the reflected light A0 as the return light when the detection light A is reflected by the reflector 11. The sway detection sensor 10 is connected to the transporter controller 8. The reflector 11 is provided on the lift table 7. As an example, the reflector 11 is provided at the center of the upper part of the lift table 7. The reflector 11 can reflect the detection light A of the sway detection sensor 10. The reflector 11 is arranged with its reflecting surface facing upward, and can reflect the detection light A from above upward. The reflector 11 is arranged directly below the sway detection sensor 10 in a state where the lift driving unit 6 is horizontal. The reflector 11 is not particularly limited, and various reflectors can be used. In the overhead transporter 1, when the lift table 7 does not sway, the sway detection sensor 10 receives the return light from the reflector 11, whereby it can detect that the lift table 7 does not sway. On the other hand, in the overhead transporter 1, when the lift table 7 sways, for example, the laser light L from the sway detection sensor 10 is not projected (not irradiated) onto the reflector 11, and the sway detection sensor 10 does not receive the reflected light A0 from the reflector 11. Thereby, it can detect that the lift table 7 sways. The sway of the lift table 7 corresponds to the movement (swing) of the vibration element with the lift driving unit 6 as the fulcrum and the suspension member B as the arm. The irradiation direction changing mechanism of the servo motor 30 can change the irradiation direction (orientation) of the detection light A irradiated by the shake detection sensor 10. The servo motor 30 is an actuator that can freely change the angle of the shake detection sensor 10 relative to the lifting drive unit 6. The servo motor 30 is provided on 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 shake detection sensor 10. Thereby, the servo motor 30 supports the shake detection sensor 10 so as to be rotatable about the rotation direction around the X direction. As a result, by driving the servo motor 30, it can change the irradiation direction of the detection light A from the shake detection sensor 10 to move along the Y direction (rotate around the X direction). The servo motor 30 is not particularly limited, and various known servo motors can be used. For example, the servo motor 30 can be a small servo motor. The servo motor 30 outputs the rotation angle of the rotating shaft 30X to the servo motor controller 32. The servo motor 30, for example, has an encoder with sufficient resolution, and it can change the irradiation direction of the detection light A steplessly. In other words, the servo motor 30 does not change the irradiation direction of the detection light A between a finite number of directions, but can freely change the irradiation direction of the detection light A to the required direction within an arbitrary range. As shown in FIGS. 4(a) to 4(g) for example, 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 thus freely change the irradiation direction of the detection light A from the shake detection sensor 10 in the Y direction, so that the irradiation direction data can be accurately reproduced. Furthermore, the irradiation direction of the detection light A can be, for example, the relative direction with respect to the lifting drive unit 6, with one side of the circumferential direction around the X axis being positive and the other side of the circumferential direction around the X axis being negative, and this is also possible. The irradiation direction of the detection light A does not have to be the direction in the absolute coordinate system. The irradiation direction of the detection light A is, for example, when the inclination of the lifting drive unit 6 with respect to the horizontal plane is 0°, the direction with the lower side of the extension direction being 0°. The servo motor controller 32 is an electronic control unit composed of a CPU, a ROM, a RAM, etc. The servo motor controller 32 controls the operation of the servo motor 30 according to, for example, a control instruction from the transport vehicle controller 8. The servo motor controller 32 can transform the output (pulse width modulation (PWM) output) from the servo motor 30. In the present embodiment, the transporter controller 8 can execute: a teaching process that acquires irradiation direction data regarding the irradiation direction (hereinafter, also simply referred to as the "irradiation direction") of the detection light A from the shaking detection sensor 10; and an irradiation direction change process that changes the irradiation direction by the servo motor 30 based on the irradiation direction data acquired in the teaching process. The teaching process and the irradiation direction change process are executed in a state where the lifting drive unit 6 is moved laterally by the lateral unit 4. The teaching process is executed, for example, at least at any one time point such as when the overhead transporter 1 ships goods, during maintenance, before actual operation, and after actual operation. The teaching process includes: a first process (first step) that irradiates the detection light A from the shaking detection sensor 10 and detects whether the shaking detection sensor 10 receives the reflected light A0 reflected by the reflector 11; a second process (second step) that changes the irradiation direction by the servo motor 30 and performs the first process a plurality of 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) that obtains the irradiation direction data based on the irradiation direction when the reflected light A0 is detected in the second process. In the second process, the irradiation direction is changed by the servo motor 30 so that the detection light A描绘出描绘出 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 fixed intervals. In the second process, the irradiation direction is not changed by scanning the detection light A, but by the operation of the servo motor 30, and the irradiation direction is changed as the posture of the shaking detection sensor 10 is deformed. In the second process, the irradiation direction can be changed by, for example, 0.1° each time by the servo motor 30. The scale width of the angle in the change of the irradiation direction is not particularly limited. The third process, based on the result of the second process, takes the center position of the irradiation direction when the reflected light A0 is first detected and the above irradiation direction when the reflected light A0 is last detected as the irradiation direction data. The irradiation direction data can be defined by the irradiation direction, can be defined by the drive amount (rotation angle) of the servo motor 30, or can be defined by other parameters. As an example, in the teaching process, when the lifting drive unit 6 is moved laterally by the lateral unit 4, as shown in Fig. 5(a), first, the irradiation direction is set to an arbitrary direction by the servo motor 30. Detection light A is irradiated from the shaking detection sensor 10, and it is detected whether the shaking detection sensor 10 receives the reflected light A0 reflected by the reflector 11 (first process). Here, the detection light A does not irradiate the reflector 11 of the lifting table 7, and the shaking detection sensor 10 does not receive the reflected light A0. At this time, the position of the detection light A is the irradiation start position outside the reflector 11. The height position of the lifting table 7 in the teaching process can be, for example, the descending position when transferring the article 200 toward the loading port 300 as a reference (the position corresponding to the loading port 300), or, for example, the lowest position within the liftable range of the lifting table 7. Subsequently, as shown in Fig. 5(b), after changing the irradiation direction by the servo motor 30, the first process is executed again. Here, the detection light A irradiates the reflector 11, and the shaking detection sensor 10 receives the reflected light A0. Thus, when the shaking detection sensor 10 does not receive the reflected light A0, after changing the irradiation direction by the servo motor 30, when the shaking detection sensor 10 receives the reflected light A0, the changed irradiation direction (i.e., the irradiation direction shown in Fig. 5(b)) is acquired as information regarding one end of the reflector 11. The information regarding one end of the reflector 11 corresponds to the information regarding the position where the area that has not received the reflected light A0 becomes the area that has received the reflected light A0. In this case, the so-called end only needs to be closer to the inside than the outer periphery (end) of the reflector 11 (the same applies hereinafter). Subsequently, as shown in Fig. 5(c), after further changing the irradiation direction by the servo motor 30, the first process is executed again. Here, the detection light A continues to irradiate the reflector 11, and the shaking detection sensor 10 receives the reflected light A0. As shown in Fig. 6(a), after further changing the irradiation direction by the servo motor 30, the first process is executed again. Here, the detection light A continues to irradiate the reflector 11, and the shaking detection sensor 10 receives the reflected light A0. Subsequently, as shown in Fig. 6(b), after further changing the irradiation direction by the servo motor 30, the first process is executed again. Here, the detection light A does not irradiate the reflector 11, and the shaking detection sensor 10 does not receive the reflected light A0. Thus, when the shaking detection sensor 10 receives the reflected light A0, after changing the irradiation direction by the servo motor 30, when the shaking detection sensor 10 does not receive the reflected light A0, the irradiation direction before the change (i.e., the irradiation direction shown in Fig. 6(a)) is acquired as information regarding the other end of the reflector 11. The position of the detection light A at this time is the irradiation end position outside the reflector 11. The information regarding the other end of the reflector 11 corresponds to the information regarding the position where the area that has received the reflected light A0 becomes the area that has not received the reflected light A0. Next, based on the result of the second process, the center position between the irradiation direction when the reflected light A0 is first detected and the irradiation direction when the reflected light A0 is last detected is used as the irradiation direction data (third process). Specifically, in the third process, when the irradiation direction to one end of the reflector 11 (refer to FIG. 5(b)) is set as θA and the irradiation direction to the other end of the reflector 11 (refer to FIG. 6(a)) is set as θB, the irradiation direction to the center position of the reflector 11 (= (θA + θB) / 2) is obtained as the irradiation direction data. In other words, based on the position where the area that has not received the reflected light A0 becomes the area that has received the reflected light A0, and the position where the area that has received the reflected light A0 becomes the area that has not received the reflected light A0, the irradiation direction is determined as the irradiation direction data in such a way that the detection light A is irradiated toward the center position of the reflector 11 (the intermediate position between the detected one end and the other end). That is, based on the result of the second process, the center position between 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 used as the irradiation direction data. And the obtained irradiation direction data is stored in the carrier vehicle controller 8. Regarding the overhead carrier vehicle 1 of this embodiment, as shown in FIG. 7(a) for example, when the lifting drive unit 6 is not moved laterally by the lateral unit 4, the irradiation direction is used as the reference direction by the servo motor 30, and the above-mentioned article 200 is transferred. The reference direction is the irradiation direction when the detection light A from the sway detection sensor 10 irradiates the center position of the reflector 11 when the inclination of the lifting drive unit 6 with respect to the horizontal plane is 0°. The reference direction corresponds to the irradiation direction of 0° for example. On the other hand, as shown in FIG. 7(b) for example, when the lifting drive unit 6 is moved laterally by the lateral unit 4, the irradiation direction change process is executed, and based on the irradiation direction data obtained in the teaching process, the irradiation direction is changed by the servo motor 30, and the above-mentioned article 200 is transferred. Thereby, even if the moving axis of the lateral unit 4 is bent and the lifting drive unit 6 moving laterally is inclined, the detection light A from the sway detection sensor 10 irradiates the reflector 11 corresponding to the inclination. The irradiation direction change process can be executed at any time point when the movement of the lifting drive unit 6 starts, during the movement, or after the movement ends. Furthermore, in this embodiment, the teaching process and the irradiation direction change process are executed when the lifting drive unit 6 is moved laterally by the lateral unit 4, but they can also be executed in other states. The teaching process and the irradiation direction change process can be executed in other states where the lifting drive unit 6 has a possibility of inclination. In summary, according to the overhead transporter 1, even for the sway detection sensor 10 used to detect one point, it is also possible to obtain the irradiation direction data based on the reflected light A0 at two or more points. Therefore, regardless of the inclination of the lifting drive unit 6, the sensor angle can be corrected in such a way that the detection light A is irradiated toward a position closer to the center of the reflector 11. Therefore, even when the inclination of the lifting drive unit 6 is different from what is expected, false detection of the sway of the lifting table 7 can be reduced. Also, for example, it can control the allowable amount of sway according to the size of the reflector 11. Also, for example, it can meet the requirements of lateral transfer and long-distance transfer in the downward direction. In the overhead transporter 1, the irradiation direction is changed in the Y direction by the servo motor 30 so that the detection light A描绘出 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 fixed intervals. 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 finally detected (the other end) is used as the irradiation direction data. In this case, it can obtain a position closer to the center of the reflector 11 as the irradiation direction data, and further reduce false detection. In the overhead transporter 1, the servo motor 30 can freely change the angle of the sway detection sensor 10 relative to the lifting drive unit 6. In this case, since it can freely change the irradiation direction using the servo motor 30, it can accurately reproduce the irradiation direction data. Since the angle of the irradiation direction can be finely adjusted (the angle can be precisely corrected) by the servo motor 30, it can surely irradiate the detection light A toward the center of the reflector 11. In the overhead transporter 1, the teaching process is executed in a state where the lifting drive unit 6 is moved laterally by the lateral unit 4, and the irradiation direction change process is executed when the lifting drive unit 6 is moved laterally by the lateral unit 4. Thereby, it can change the irradiation direction when moving the lifting drive unit 6 using the lateral unit 4. The irradiation direction determination method includes: a first step of irradiating the detection light from the sway detection sensor 10 and detecting whether the sway detection sensor 10 receives the reflected light A0 reflected by the reflector 11 disposed on the lifting table 7; a second step of changing the irradiation direction by the servo motor 30 and performing the first step a plurality of 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 step of obtaining the irradiation direction data based on the irradiation direction when the reflected light A0 is detected in the second step. In this irradiation direction determination method, it can accurately correct the irradiation direction of the detection light A for the unexpected inclination of the sway detection sensor 10, thereby preventing false detection. Therefore, it can improve the accuracy of the sway detection of the lifting table 7. In summary, although the embodiments have been described, the aspects of the present invention are not limited to the above embodiments. Various changes can be made without departing from the gist of the aspects of the present invention. In the above embodiment, the teaching process can be executed in each state where the lifting drive unit 6 is moved laterally by the lateral unit 4 by the first to Nth movement amounts (N is an integer of 2 or more). In this case, for example, as shown in FIG. 8, a data table (teaching data) including irradiation direction data for each of a plurality of lateral movement amounts can be obtained. α in FIG. 8 is the reference direction. In the data table of FIG. 8, the lateral movement amount is set to a 25% scale, but the scale width is not particularly limited and can be, for example, scales such as 1%, 2%, 4%, 5%, 10%. According to the execution of such a teaching process, the irradiation direction change process can be performed by the servo motor 30 according to the irradiation direction data corresponding to any one of the first to Nth movement amounts in the data table when the lateral unit 4 moves the lifting drive unit 6 laterally by any one of the first to Nth movement amounts. In this case, the irradiation direction can be changed according to the movement amount of the lateral unit 4 moving the lifting drive unit 6 laterally. The irradiation direction can be used more precisely and differentiated. Furthermore, the irradiation direction data can be, for example, a variable parameter centered on the reference angle and with the movement amount of the lifting drive unit 6 as a variable. In the above embodiment, the teaching process can be executed in each case of transferring the article 200 to a plurality of loading ports 300. In this case, for example, as shown in FIG. 9, a data table including irradiation direction data for each of a plurality of loading ports 300 can be obtained. In the data table of FIG. 9, the number of the loading ports 300 is not particularly limited. According to the execution of such a teaching process, the irradiation direction change process can be performed by the servo motor 30 according to the irradiation direction data corresponding to any one of the plurality of loading ports 300 in the data table when transferring the article 200 to any one of the plurality of loading ports 300. In this case, the irradiation direction can be changed according to the loading port 300 for transferring the article 200. The irradiation direction can also be used more precisely and differentiated. The teaching process can be carried out in accordance with the transfer destination. Also, for example, even if the lifting drive unit 6 is tilted due to the track 20 being tilted in the left - right direction, the detection light A can still capture the center of the reflector 11. It can also correspond to the transfer without the lateral movement of the lifting drive unit 6. That is, whether or not the lateral unit 4 moves the lifting drive unit 6, it can perform the teaching process and the irradiation direction change process for each of the plurality of loading ports 300. Alternatively, it can separately obtain the irradiation direction data corresponding to each loading port 300 in FIG. 9 according to whether or not the lateral unit 4 moves the lifting drive unit 6. In this case, it can change the irradiation direction by the servo motor 30 according to the irradiation direction data corresponding to each loading port 300 and corresponding to the presence or absence of lateral movement. Also, alternatively, it can separately obtain the irradiation direction data corresponding to each loading port 300 in FIG. 9 according to each of the plurality of lateral movement amounts caused by the lateral unit 4. In this case, it can change the irradiation direction by the servo motor 30 according to the irradiation direction data corresponding to each loading port 300 and corresponding to the plurality of lateral movement amounts. In the teaching process performed for each of the plurality of loading ports 300, the height position of the lifting table 7 can be the descending position (the position corresponding to each loading port 300) when transferring the article 200 toward each loading port 300. In the above embodiment, as shown in FIG. 10, a servo motor 130 that rotates the servo motor 30 in the rotational direction around the Y axis can be further provided as an irradiation direction change mechanism. In this case, it can move the irradiation direction in the Y direction by the servo motor 30 and move the irradiation direction in the X direction by the servo motor 130. In the above embodiment, the irradiation direction change mechanism is not limited to the servo motor 30, and it can also be other mechanisms. As the irradiation direction change mechanism, various known actuators can be adopted. For example, a stepping motor can be used as the irradiation direction change mechanism. When using a stepping motor, an absolute sensor can be provided, and a home return can also be performed using a dog or the like. In the above embodiment, although the shaking of the lifting table 7 is detected by the shaking detection sensor 10, the shaking detection sensor 10 is not particularly limited as the sensor of one aspect of the present invention. The sensor of one aspect of the present invention can be, for example, a so-called downward-looking sensor that irradiates a detection light with directivity near the descending destination of the lifting table 7 to detect a foreign object (obstacle) at the descending destination of the lifting table 7. In each of the above embodiments and modifications, it is not limited to the above materials and shapes, and various materials and shapes can be applied. Each of the components in the above embodiments or modifications can be arbitrarily applied to the components in other embodiments or modifications. A part of each of the components in the above embodiments or modifications can be appropriately omitted without departing from the gist of one aspect of the present invention. 1: Overhead transfer vehicle 2: Frame unit (body part) 3: Travel unit 4: Lateral unit (lateral extension mechanism) 5: θ unit 6: Lifting drive unit (lifting drive part) 7: Lifting platform 8: Transfer vehicle controller (control part) 10: Shaking detection sensor (sensor) 11: Reflector 12: Holding part 15: Central frame 16: Front frame 17: Rear frame 20: Track 30, 130: Servo motor (irradiation direction change mechanism, actuator) 30X: Rotation axis 32: Servo motor controller 200: Article 201: Flange 300: Loading port (placement part) A: Detection light A0: Reflected light B: Suspension member L: Laser light X: Direction Y: Direction Z: Direction FIG. 1 is a side view showing an overhead transfer vehicle according to an embodiment. FIG. 2 is a front view showing the overhead transfer vehicle of FIG. 1. FIG. 3 is a side view showing the shaking detection sensor. FIG. 4(a) is a front view for explaining the change of the irradiation direction by using a servo motor. FIG. 4(b) is a front view for explaining the change of the irradiation direction by using a servo motor. FIG. 4(c) is a front view for explaining the change of the irradiation direction by using a servo motor. FIG. 4(d) is a front view for explaining the change of the irradiation direction by using a servo motor. FIG. 4(e) is a front view for explaining the change of the irradiation direction by using a servo motor. FIG. 4(f) is a front view for explaining the change of the irradiation direction by using a servo motor. FIG. 4(g) is a front view for explaining the change of the irradiation direction by using a servo motor. FIG. 5(a) is a front view for explaining the teaching process. FIG. 5(b) is a front view showing the subsequent of FIG. 5(a). FIG. 5(c) is a front view showing the subsequent of FIG. 5(b). FIG. 6(a) is a front view showing the subsequent of FIG. 5(c). FIG. 6(b) is a front view showing the subsequent of FIG. 6(a). FIG. 7(a) is a front view showing an example of transferring an article by the overhead transfer vehicle. FIG. 7(b) is a front view showing another example of transferring an article by the overhead transfer vehicle. FIG. 8 is a diagram showing a data table including irradiation direction data for each of a plurality of lateral movement amounts. FIG. 9 is a diagram showing a data table including irradiation direction data for each of a plurality of loading ports. FIG. 10 is a side view showing a shaking detection sensor according to a modified example 4: Lateral unit (lateral extension mechanism) 5: θ unit 6: Lifting drive unit (lifting drive part) 10: Shaking detection sensor (sensor) 16: Front frame 17: Rear frame 30: Servo motor (irradiation direction change mechanism, actuator) 30X: Rotation axis 32: Servo motor controller A: Detection light B: Suspension member X: Direction Y: Direction Z: Direction

Claims

1. An overhead conveyor truck comprising: a main body; a lifting platform that is movable relative to the main body; a lifting drive unit that moves the lifting platform up and down; a sensor disposed on the lifting drive unit that illuminates a detection light at a point downwards and receives reflected light from the detection light; an illumination direction changing mechanism that can change the illumination direction of the detection light illuminated by the sensor; and a control unit that controls at least the operation of the sensor and the illumination direction changing mechanism; wherein a reflector that reflects the detection light from the sensor is disposed on the lifting platform, and the control unit can perform: a teaching process that acquires illumination direction data related to the illumination direction; and an illumination direction changing process that changes the illumination direction by means of the illumination direction changing mechanism based on the illumination direction data acquired in the teaching process; wherein the teaching process includes: a first process that illuminates the detection light from the sensor and detects whether the sensor receives the reflected light reflected by the reflector. The second process involves changing the illumination direction using the illumination direction changing mechanism and performing the first process multiple times to detect the reflected light at least once at each end of the reflector. The third process involves determining the illumination direction data based on the illumination direction when the reflected light is detected in the second process. Based on the result of the second process, the third process uses the center position of the illumination direction when the reflected light is first detected and the illumination direction when the reflected light is last detected as the illumination direction data.

2. As in request item 1, the elevated transport vehicle, wherein, The second process described above changes the irradiation direction by means of the irradiation direction changing mechanism, so that the detection light draws a straight line with the outside of the reflector as the irradiation start position and the irradiation end position, and the first process described above is performed at fixed intervals.

3. As in request item 1 or 2, the elevated transport vehicle, wherein, The aforementioned illumination direction changing mechanism includes an actuator that allows for flexible adjustment of the angle between the aforementioned sensor and the aforementioned lifting drive unit.

4. As in request item 3, the elevated transport vehicle, wherein, The aforementioned actuator is a servo motor.

5. For example, the elevated transport vehicle requested in item 1 or 2, wherein, It is equipped with a lateral extension mechanism that moves the lifting drive unit to the side relative to the main body; the teaching process is performed when the lifting drive unit is moved to the side by means of the lateral extension mechanism; the illumination direction change process is performed when the lifting drive unit is moved to the side by means of the lateral extension mechanism or when it has already moved.

6. As in request item 1 or 2, the elevated transport vehicle, wherein, The device includes a lateral extension mechanism that allows the lifting drive unit to move laterally relative to the main body. The teaching process is performed in each state where the lifting drive unit has moved laterally by an amount from the first to the Nth (N is an integer of 2 or more) via the lateral extension mechanism. The illumination direction change process changes the illumination direction by the illumination direction change mechanism based on the illumination direction data corresponding to any of the first to the Nth amounts of movement, when the lifting drive unit has moved laterally via the lateral extension mechanism or has moved by any of the first to the Nth amounts of movement.

7. The overhead conveyor vehicle as described in claim 1 or 2 is a conveyor vehicle capable of transferring items to a plurality of loading units, and the above-mentioned teaching process is performed in each case of transferring the above-mentioned items to a plurality of loading units. The above-mentioned illumination direction change process is performed by the above-mentioned illumination direction change mechanism to change the illumination direction when the above-mentioned items are transferred to any of the plurality of loading units, based on the above-mentioned illumination direction data corresponding to any of the plurality of loading units.

8. A method for determining the illumination direction of a sensor, wherein the method is used in an overhead conveyor to determine the illumination direction of a detection light irradiated by the sensor, the overhead conveyor comprising: a main body; a lifting platform that can be raised and lowered relative to the main body; a lifting drive unit that raises and lowers the lifting platform; and the sensor disposed in the lifting drive unit and detecting the swaying of the lifting platform; the method for determining the illumination direction of the sensor comprises: a first step of irradiating the detection light from the sensor and detecting whether the sensor receives reflected light reflected by a reflector disposed on the lifting platform; a second step of changing the illumination direction by means of an illumination direction changing mechanism and performing the first step a plurality of times, such that at least one reflected light is detected at one end side and the other end side of the reflector; and a third step of determining illumination direction data related to the illumination direction based on the illumination direction when the reflected light is detected in the second step. Based on the result of step 2, step 3 takes the center position of the irradiation direction when the reflected light was first detected and the irradiation direction when the reflected light was last detected as the irradiation direction data.

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