Method for recognizing location of transport vehicle for automated overhead hoist transport system

Abstract

To provide a method for recognizing a location of a transport vehicle for an automated overhead hoist transport system that can acquire accurate location information of the transport vehicle in real time.SOLUTION: A method for recognizing a location of a transport vehicle for an automated overhead hoist transport system comprises: an image acquiring step of acquiring a first image acquired by imaging, by an imaging unit, a rail immediately before the transport vehicle starts traveling, and a second image acquired by imaging the rail at a current location of the transport vehicle that is traveling; a feature point setting step of setting, as a feature point, an arbitrary pattern in the first image; and a location information calculating step of calculating current location information of the transport vehicle based on the location information acquired in a reference location information acquiring step, and based on a movement amount depending on a movement displacement of a feature point which is detected by comparing the first image with the second image.SELECTED DRAWING: Figure 2

Description

Technical Field

[0001] The present invention relates to a method for recognizing the position of a carrier vehicle in a ceiling-type automatic transport system. More specifically, it relates to a method for recognizing the position of a carrier vehicle in a ceiling-type automatic transport system that does not require high-altitude work, can reduce working time and required costs, can accurately and quickly recognize the current position of the carrier vehicle during line operation, and can precisely grasp the fault diagnosis position.

Background Art

[0002] Generally, in semiconductor and OLED production lines, OHT (Overhead Hoist Transport) is widely used as a carrier vehicle for transporting various transfer objects such as wafers. The OHT moves along a rail installed on the ceiling of the production line to the destination according to a transfer command, and transfers the object through a handoff (the operation of transferring the logistics from one of the OHT and the production equipment to the other).

[0003] Normally, in a production line, where there are a large number of production equipments, a corresponding number of OHTs (hereinafter referred to as "carrier vehicles") repeatedly perform the handoff process while moving along the rail. Generally, in order to perform a stable handoff operation, after the carrier vehicle stops at the working position on the rail, the handoff operation is performed. At this time, in order to perform a smooth and accurate handoff operation between the carrier vehicle and the target equipment, it is necessary for the carrier vehicle to stop accurately at the working position. Therefore, conventionally, a position display part such as a QR code (registered trademark), barcode, tag, etc. is provided at the working position of the rail, a display part reader is installed on the carrier vehicle, and the carrier vehicle is stopped by recognizing the position display part.

[0004] Here, although it varies depending on the scale of the factory and the number of equipment, generally, thousands to tens of thousands or more position display parts must be provided at determined positions on the production line. However, it takes a lot of time to design the positions of the position display parts during the process design. When the position of the position display part needs to be changed due to process layout changes, equipment position changes, etc., it also takes a considerable amount of time to remove and reinstall the existing position display parts, which has a problem of affecting the production efficiency of the production line.

[0005] Not only that, the height of the ceiling where the rails are installed is usually 3m or more, and since the reinstallation work of the above-mentioned position display parts is also carried out at a high position, there is a problem that a lot of costs are additionally incurred to ensure the safety of the operators.

[0006] On the other hand, in the semiconductor line site that emphasizes work efficiency, attempts to pre-diagnose failures and prevent accidents are increasing. As part of this, various devices (vibration sensors, noise sensors, cameras, etc.) are installed on the transport cart, and failure analysis data is collected while moving. However, since the position information between the position display parts during line operation, that is, the current position information of the transport cart in the area between adjacent nodes, cannot be accurately recognized, even if failure diagnosis is performed using the collected data, it is difficult to precisely confirm the failure position.

[0007] A method of determining the current position of the transport cart using an acceleration sensor has also been proposed, but basically, the acceleration sensor has a lot of noise and a large position error, and it is difficult to apply it to an OHT system that requires an accuracy of several millimeters or less, such as a semiconductor production line.

Prior Art Documents

Patent Documents

[0008]

Patent Document 1

Patent Document 2

Summary of the Invention

Problems to be Solved by the Invention

[0009] The present invention has been made to solve the above-described problems. The object of the present invention is to obtain accurate position information of a transport cart in real time, and by determining a working position through it, a position display unit can be installed in the same manner for each semiconductor factory at the time of process design, significantly reducing the process design time and the required cost. Even if the working environment is changed, such as a change in the layout of the process or a change in the position of the equipment, it is not necessary to reinstall the position display unit, and no high-altitude work is required for the reinstallation work of the position display unit. Therefore, the working time and the required cost can be greatly reduced, post-management can be improved epochally, and the efficiency of logistics transportation can be greatly improved. An object of the present invention is to provide a method for recognizing the position of a transport cart of a ceiling-type automatic transport system.

[0010] Another object of the present invention is to transmit an abnormal occurrence or an abnormal sign, such as damage, breakage, or deformation of a rail during the travel of a transport cart, together with an abnormal sign signal to a preset terminal as an abnormal sign occurrence position, and detect the abnormal state of the rail in real time. An object of the present invention is to provide a method for recognizing the position of a transport cart of a ceiling-type automatic transport system.

Means for Solving the Problems

[0011] The method for recognizing the position of a carrier cart in a ceiling-type automatic conveying system according to the present invention includes a rail installed along a preset path on the ceiling of a work site, a plurality of position display units attached at preset intervals on one side of the rail, a carrier cart installed to be able to travel along the rail, and an imaging unit installed on one side of the carrier cart to image one side of the rail corresponding to the carrier cart and the position display unit in the rail to obtain an image. In the method for recognizing the position of a carrier cart for a ceiling-type automatic conveying system, an image acquisition step of acquiring a first image of one side of the rail captured by the imaging unit immediately before the carrier cart travels and a second image of one side of the rail at the current position of the traveled carrier cart; a reference position information acquisition step of acquiring position information corresponding to the detected position display unit from pre-stored position data when the position display unit in the first image is detected; a feature point setting step of setting an arbitrary pattern in the first image as a feature point; and a position information calculation step of calculating the current position information of the carrier cart based on the position information acquired in the reference position information acquisition step and the amount of movement due to the displacement of the feature point detected by comparing the first image, the second image, and the feature point.

[0012] The position information calculation step preferably includes a movement displacement detection step of comparing the first image and the second image to detect the movement displacement of the feature point, a pixel number measurement step of measuring the number of pixels on the X-axis and Y-axis from the position of the feature point on the first image to the position of the feature point on the second image due to the detected movement displacement of the feature point, a movement amount calculation step of calculating the movement amount of the carrier cart based on the measured number of pixels on the X-axis and Y-axis, and a position information acquisition step of obtaining the current position information of the carrier cart by adding the calculated movement amount of the carrier cart to the position information acquired in the reference position information acquisition step.

[0013] The position information calculation stage further includes an interval calculation stage for calculating the distance between the position display units using the current position information of the transport cart, and a correction value calculation stage for comparing the distance between the position display units calculated in the interval calculation stage with the actual distance between the position display units stored in advance, and calculating a correction value for the movement amount of the transport cart based on the difference value. After the correction value is calculated, when the movement amount calculation stage is performed, the calculated correction value can be reflected in the movement amount of the transport cart.

[0014] Another method for recognizing the position of a carrier vehicle in a ceiling-type automatic conveying system according to the present invention is installed along a preset path on the ceiling of a work site, and a first horizontal line and a second horizontal line are displayed parallel to each other along the length direction at the upper and lower parts. A rail with a position recognition line connecting the first horizontal line and the second horizontal line diagonally is displayed, a plurality of position display parts are attached at preset intervals on one side of the rail, a carrier vehicle is installed to be able to travel along the rail, and an imaging part is installed on one side of the carrier vehicle to detect the position display part and perform line scanning on one side of the rail corresponding to the carrier vehicle in the rail to obtain an image. In the method for recognizing the position of a carrier vehicle for a ceiling-type automatic conveying system, it includes an image acquisition step of acquiring an image by performing line scanning on one side of the rail at the current position of the carrier vehicle, a reference position information acquisition step of acquiring position information corresponding to the position display part detected by the imaging part using pre-saved position data when the position display part is detected by the imaging part, and a position information calculation step of acquiring the current position information of the carrier vehicle based on the position information of the position display part acquired in the reference position information acquisition step and the movement amount of the carrier vehicle calculated by analyzing the image. The position information calculation step includes an intersection detection step of detecting intersections P1, P2, and P3 where the scanning line of the vertical imaging part in the image intersects the first and second horizontal lines and the position recognition line respectively, a movement amount calculation step of setting any one of the heights from P2 to P3 or from P3 to P1 as h and substituting this into the following [mathematical formula] to calculate the actual movement amount (M'') of the carrier vehicle, and a position information acquisition step of adding the actual movement amount of the carrier vehicle calculated to the position information of the position display part acquired in the reference position information acquisition step to obtain the current position information of the carrier vehicle. It is characterized by including the above steps. (Here, D is the X-axis distance between the first point where the position recognition line intersects the first horizontal line and the second point where the position recognition line intersects the second horizontal line, and H is the interval between the first and second horizontal lines.)

[0015]

Number

[0016] When the movement displacement of the feature points detected in the movement displacement detection stage deviates from a preset reference range, it is determined as a sign of abnormality, and an abnormality sign detection stage may be further included, which transmits the current position information of the carrier cart together with the abnormality sign signal to a preset target terminal device.

[0017] When the position display unit is detected in the reference position information acquisition stage, it is preferable to further include an initialization stage for initializing the movement amount of the carrier cart.

Advantages of the Invention

[0018] According to the present invention, by acquiring the accurate position information of the carrier cart in real time and determining the working position through it, the position display unit can be installed in the same way for each semiconductor factory during the process design, which can not only greatly reduce the process design time and the required cost, but also, even if the working environment is changed, such as the layout change of the process or the position change of the equipment, there is no need to reinstall the position display unit, and there is no need for high-altitude work due to the reinstallation work of the position display unit, and the working time and required cost can also be greatly reduced, which can epoch-makingly improve the after-sales management and greatly improve the efficiency of logistics transportation. In addition, when an abnormality occurs or a sign of abnormality appears during the running of the carrier cart, such as damage, breakage or deformation of the rail, the present invention can transmit it together with the abnormality sign signal to a preset terminal device at the position where the abnormality sign occurs to detect the abnormal state of the rail in real time.

Brief Description of the Drawings

[0019]

Figure 1

Figure 2

Figure 3

Figure 4

Figure 5

Figure 6

Figure 7

Mode for Carrying Out the Invention

[0020] Hereinafter, with reference to the accompanying drawings, a preferred embodiment of the present invention will be described in detail.

[0021] FIG. 1 is a drawing schematically illustrating a ceiling-type automatic conveyance system according to an embodiment of the present invention. Prior to describing a method for recognizing the position of a carrier vehicle in a ceiling-type automatic conveyance system according to an embodiment of the present invention, the basic structure of the ceiling-type automatic conveyance system (1) according to this embodiment relates to a logistics conveyance device that transfers logistics by performing a handoff with specific equipment at a work site, and includes a rail (10) installed along a preset path on the ceiling of the work site, a position display unit (B) attached at preset intervals along the rail (10), a carrier vehicle (20) traveling along the rail (10), an imaging unit (30) installed on one side of the carrier vehicle (20), and an analysis unit (40) that analyzes an image to recognize the current position of the carrier vehicle (20).

[0022] As the position display unit (B), a barcode, an RF tag, a QR code (registered trademark), or the like can be used. Each attached position display unit (B) stores a unique identification number, and the position information based on the identification number is stored in advance in the carrier vehicle or an external server. And the imaging unit (30) according to this embodiment is installed on one side of the transport cart (20) and travels together with the transport cart (20), and plays a role of imaging one side of the rail (10) during the traveling process of the transport cart (20) and obtaining an image thereof. Such an imaging unit (30) uses a code reader, an optical sensor, an image sensor, etc. Among these, it is composed of two types of equipment such as a code reader and an optical sensor. The analysis unit (40) analyzes the image acquired by the imaging unit (30) to recognize the current position of the transport cart (20). The following describes the method for recognizing the position of the transport cart of the ceiling-type automatic transport system described above.

[0023] FIG. 2 is a sequence diagram sequentially illustrating the method for recognizing the position of the transport cart of the ceiling-type automatic transport system according to an embodiment of the present invention, FIG. 3 is a drawing schematically illustrating the principle of detecting the moving direction according to an embodiment of the present invention, and FIG. 4 is a drawing schematically illustrating the principle of measuring the number of pixels according to an embodiment of the present invention.

[0024] As shown in FIG. 2, the method for recognizing the position of the transport cart of the ceiling-type automatic transport system according to an embodiment of the present invention includes an image acquisition stage (S10), a reference position information acquisition stage (S20), a feature point setting stage (S30), and a movement displacement detection stage and a position information calculation stage (S40).

[0025] Image Acquisition (S10) The imaging unit (30) is installed on one side of the transport cart (20) and plays a role of imaging one side corresponding to the transport cart (20) among one sides of the rail (10), but images the rail (10) immediately before the transport cart (20) travels along the rail (10) to obtain a first image. Thereafter, during the process of the transport cart (20) traveling along the rail (10), the rail (10) is also imaged to obtain a second image, and a large number of images obtained in this way are transmitted to the analysis unit (40).

[0026] Reference Position Information Acquisition (S20) Before analyzing the position information of the transport cart (20), the analysis unit (40) determines whether the position display unit (B) in the first image is detected. When attempting to calculate the current real-time position of the transport cart (20), for obtaining reference position information, if the position display unit in the first image is detected, the unique identification number is deciphered, and among the position data pre-stored in the transport cart or the server, the position information corresponding to the deciphered identification number is obtained, and the reference position is set.

[0027] Feature point setting (S30) Also, in the image transmitted from the imaging unit (30), the analysis unit sets a specific area or a specific position in the first image as a feature point (T). In this embodiment, as shown in FIG. 3, for the sake of convenience of explanation, one certain pixel is illustrated as the feature point (T), but the present invention is not necessarily limited thereto, and a specific pattern can also be set as the feature point (T).

[0028] Position information calculation (S40) After setting the feature points, the analysis unit (40) calculates the position information of the transport cart (20). The position information calculation step (S40) according to this embodiment includes a movement displacement detection step (S41), a pixel number measurement step (S42), a movement amount calculation step (S43), and a position information acquisition step (S44). First, in the movement displacement detection step (S41), as shown in FIG. 3, the positions of the feature points on the first image and the second image are compared to detect the movement direction of the feature point (T). If the movement direction of the feature point (T) is detected, in the pixel number measurement step (S42), as shown in FIG. 4, from the initial position of the feature point (T) to the current position of the moved feature point (T), that is, between the position of the feature point (T) on the first image and the position of the feature point on the second image, the number of pixels in the X and Y axes (Δx, Δy) is measured.

[0029] Next, the measured number of pixels in the X and Y axes is substituted into the following formula 1 set in advance to calculate the actual movement amount of the transport cart (20).

Equation

[0030] In this way, once the actual movement amount of the carrier cart (20) is calculated, the current position information of the carrier cart (20) is obtained by adding up the actual movement amount of the carrier cart (20) calculated to the reference position acquired through the position display unit (B) above. (S44)

[0031] On the other hand, in the position information calculation step (S40) according to this embodiment, an interval calculation step (S45) for calculating the distance between the position display unit (B) and the position display unit (B) using the current position information of the carrier cart (20), and the actual distance between the position display units (B) and (B) saved in advance are compared with the measured distance between the position display units (B) and (B) calculated above, and a correction value calculation step (S46) for calculating a correction value for the movement amount of the carrier cart (20) based on the value of the difference is further included.

[0032] That is, in this embodiment, by reflecting the correction value obtained in the correction value calculation step (S46) through the interval calculation step (S45) in the movement amount calculated in the next movement amount calculation step (S43) of the carrier cart (20), errors due to various environmental factors such as the installation angle of the actual imaging unit (30) being displaced are periodically corrected to more accurately grasp the position information of the carrier cart (20).

[0033] On the other hand, in the present invention, when the movement displacement of the feature point detected in the movement displacement detection step (S41) deviates from a preset reference range, that is, when it shows vibrations exceeding the reference value or discontinuous / abnormal rotation angles, it is determined as an abnormal symptom such as a crack, break, or deformation of the rail (10), and an abnormal symptom signal is generated. At the same time, after obtaining the current position information of the carrier cart (20) in the above-described manner, it is transmitted to a preset target terminal, thereby having an additional feature of being able to monitor the abnormal symptoms and abnormal states of the rail (10) in real time.

[0034] FIG. 5 is a sequence diagram sequentially illustrating a method for recognizing the position of a carriage in a ceiling-type automatic conveying system according to another embodiment of the present invention, FIG. 6 is a drawing illustrating one side of a rail on which a first and a second horizontal lines and a position recognition line are displayed according to another embodiment of the present invention, and FIG. 7 is a drawing illustrating intersections P1, P2, and P3 according to an embodiment of the present invention.

[0035] In the embodiments of FIGS. 5 to 7, the accuracy is improved and the calculation speed is increased to obtain position information more quickly. In this embodiment, different from the previous embodiment, a line scan camera and a barcode reader are both used in the imaging unit (30). As shown in FIG. 6, on the rail (10), a first horizontal line (L1) and a second horizontal line (L2) are displayed parallel to each other along the length direction at the upper and lower parts, and a position recognition line (L3) connecting the first horizontal line (L1) and the second horizontal line (L2) diagonally is displayed.

[0036] The method for recognizing the position of a carriage in a ceiling-type automatic conveying system according to another embodiment of the present invention includes, as shown in FIG. 5, an image acquisition step (S10'), a reference position information acquisition step (S20'), and a position information calculation step (S30'). In the image acquisition step (S10'), the imaging unit (30) acquires an image obtained by line-scanning one side of the rail (10) at the current position of the carriage (20). At this time, as described above, since a line scan camera is used in the imaging unit (30), an image in a form corresponding to the scan line of the imaging unit (30), that is, a vertically-shaped image is acquired.

[0037] In the reference position information acquisition stage (S20’), when detecting the position display part (B) with a barcode reader provided together with the line scan camera, it decodes the unique identification number, and among the position data pre-stored in the transport cart or the server, acquires the position information corresponding to the decoded identification number, sets the reference position, and initializes the movement amount of the already calculated transport cart (20). In this way, every time each position display part (B) is detected, the movement amount of the transport cart (20) is initialized, and by recalculating the movement amount of the transport cart (20) based on the position information from the pre-stored position display part (B), it prevents the accumulation of the movement amount error of the transport cart (20), and further calculates a more accurate movement amount of the transport cart (20).

[0038] On the other hand, in this embodiment, it is described that, together with the line scan camera, a separate barcode reader is provided and the position display part is detected through the barcode reader. However, the present invention is not necessarily limited to this. The barcode reader can be omitted, and the position display part can also be detected by accumulating the vertical linear images acquired by the line scan camera.

[0039] In the position information calculation stage (S30’) of this embodiment, different from the previous embodiment, it consists of an intersection detection stage (S31’), a movement amount calculation stage (S32’), and a position information acquisition stage (S33’). As shown in FIG. 7, the intersection detection stage (S31’) detects the intersections P1, P2, P3 where the image acquired in the image acquisition stage (S10’), that is, the scan line of the imaging unit (30), intersects with the first and second horizontal lines (L1, L2) and the position recognition line (L3) respectively.

[0040] In the movement amount calculation stage (S32’) of this embodiment, by detecting the position of P3, which is a feature point, using only the information of the intersections P1, P2, P3, the current position of the transport cart (20) is recognized. This will be described below. First, among each intersection detected in the intersection detection stage, the actual height values (h) of P2 and P3 are calculated. The actual height values (h) of P2 and P3 can be calculated by the following formula.

[0041] [Number] (Here, x is the number of pixels between P1 and P2, y is the number of pixels between P2 and P3, and H is the distance between the first horizontal line (L1) and the second horizontal line (L2).)

[0042] At this time, starting from the value of the distance (H) between the first and second horizontal lines (L1, L2), the value of the X-axis distance (D) between the first point where the position recognition line (L3) intersects the first horizontal line (L1) and the second point where the position recognition line (L3) intersects the second horizontal line (L2) is a fixed value fixed at the time when the first and second horizontal lines (L1, L2) and the position recognition line (L3) are displayed on the rail (10). Therefore, this value is saved in advance. In this way, if the value (h) of the actual height between P2 and P3 is calculated, it is substituted into the following [Equation 3] to calculate the actual movement amount (M'') of the carriage (20).

[0043] [Number] (Here, D is the X-axis distance between the first point where the position recognition line (L3) intersects the first horizontal line (L1) and the second point where the position recognition line (L3) intersects the second horizontal line (L2), and H is the distance between the first and second horizontal lines (L1, L2).)

[0044] Finally, in the position information acquisition step (S33'), the actual movement amount (M'') of the carriage (20) is added to the position information acquired in the reference position information acquisition step (S20') to acquire the current position information of the carriage (20). Although the present invention has been described in connection with preferred embodiments, various modifications and variations can be made without departing from the gist and scope of the invention. Therefore, the appended claims cover modifications and variations belonging to the present invention. [Explanation of Reference Numerals]

[0045] 10 Rail 20 Carriage 30 Imaging unit 40 Analysis unit L1 First horizontal line L2 Second horizontal line L3 Position recognition line B Position display section

Claims

1. A method for recognizing the position of a transport vehicle for a ceiling-mounted automatic transport system, comprising: a rail installed along a preset route on a ceiling of a work site; a number of position display units attached at preset intervals to one side of the rail; a transport vehicle installed to be able to run along the rail; and an imaging unit installed on one side of the transport vehicle for imaging the rail, the side of the rail corresponding to the transport vehicle, and the position display unit to obtain an image, an image acquiring step of acquiring a first image by the imaging unit of one side of the rail immediately before the transport vehicle runs, and a second image by the imaging unit of one side of the rail at a current position of the transport vehicle that has run; acquiring a reference position information of acquiring position information corresponding to the detected position display unit from pre-stored position data when the position display unit is detected in the first image; a feature point setting step of setting an arbitrary pattern in the first image as a feature point; a position information calculation step of calculating current position information of the transport vehicle based on the position information acquired in the reference position information acquisition step and a movement amount due to a movement displacement of a feature point detected by comparing the first image with the second image; 13. A method for recognizing the position of a transport vehicle in a ceiling-mounted automatic transport system, comprising:

2. The position information calculation step a displacement detection step of detecting a displacement of the feature point by comparing the first image with the second image; measuring the number of pixels in the X-axis and Y-axis directions from the position of the feature point on the first image to the position of the feature point on the second image according to the movement of the detected feature point; a movement amount calculation step of calculating a movement amount of the transporting carriage based on the measured number of pixels in the X-axis and Y-axis; a position information acquisition step of acquiring current position information of the transporting vehicle by adding the calculated movement amount of the transporting vehicle to the position information acquired in the reference position information acquisition step; 2. The method for recognizing the position of a transporting carriage in a ceiling-mounted automatic transport system according to claim 1, further comprising:

3. The position information calculation step A distance calculation step of calculating a distance between the position display units by using current position information of the transport vehicle; and The method further includes a correction value calculation step of comparing a distance between the position display units calculated in the distance calculation step with an actual distance between the position display units stored in advance, and calculating a correction value for a movement amount of the transporting vehicle based on the difference, 3. The method for recognizing a position of a transporting vehicle in a ceiling-mounted automatic transport system according to claim 2, wherein when the movement amount calculation step is performed after the correction value is calculated, the correction value is reflected in the calculated movement amount of the transporting vehicle.

4. 1. A method for recognizing the position of a transporting platform for a ceiling-type automatic transport system, comprising: a rail installed on a ceiling of a work site along a preset path, with first and second horizontal lines parallel to each other at upper and lower parts along a length direction, and with a position recognition line diagonally connecting the first and second horizontal lines; position display units installed at preset intervals on one side of the rail; a transporting platform installed to be able to travel along the rail; and an imaging unit installed on one side of the transporting platform to detect the position display units and to line-scan one side of the rail corresponding to the transporting platform within the rail to obtain an image, an image acquiring step of acquiring an image by line scanning one side of the rail at a current position of the transport vehicle; acquiring reference position information for acquiring position information corresponding to the detected position display unit from prestored position data when the position display unit is detected by the imaging unit; and acquiring current position information of the transport vehicle based on the position information of the position display unit acquired in the reference position information acquisition step and the movement amount of the transport vehicle calculated by analyzing the image, The position information calculation step includes: detecting intersections P1, P2, and P3 at which vertical scan lines of the imaging unit intersect with the first and second horizontal lines and the position recognition line in the image; a movement amount calculation step of setting either one of the height from P2 to P3 or the height from P3 to P1 as h and substituting it into the following [Equation] to calculate an actual movement amount (M'') of the transporting cart; a position information acquisition step of acquiring current position information of the transporting cart by adding an actual movement amount of the transporting cart calculated to the position information of the position display unit acquired in the reference position information acquisition step. [0010] (where D is the X-axis distance between a first point where the position recognition line intersects with a first horizontal line and a second point where the position recognition line intersects with a second horizontal line, and H is the distance between the first and second horizontal lines.)

5. 3. The method of claim 2, further comprising an abnormality sign detection step of determining that the movement displacement of the feature point detected in the movement displacement detection step is outside a predetermined reference range as an abnormality sign and transmitting current position information of the transport vehicle together with an abnormality sign signal to a predetermined target terminal.

6. 5. The method for recognizing the position of a transporting cart in a ceiling-mounted automatic transport system according to claim 1, further comprising an initialization step of initializing a movement amount of the transporting cart when the position display unit is detected in the reference position information acquisition step.

Images