A four-way shuttle vehicle and a method for positioning a hollowed-out tray thereof

Abstract

The application provides a four-way shuttle vehicle and a method for positioning a hollow tray of the four-way shuttle vehicle. A plurality of pairs of linear photoelectric sensors are arranged at the edges of the body of the four-way shuttle vehicle, and the interval distance between the light emitting positions in each pair of linear photoelectric sensors is less than the edge width of the tray leg. Thus, the four-way shuttle vehicle can be positioned by the linear photoelectric sensors detecting the distance between the light emitting positions and the edge of the tray leg, so that the four-way shuttle vehicle is opposite the bottom of the goods when lifting the tray, the goods on the tray can be stably lifted, and the goods can be prevented from overturning or being blocked during transportation. The detection mechanism of the application is simple, and the existing linear photoelectric sensor can be directly used by being installed at a specific position of the body to realize detection and positioning, so that the actual position of the hollow tray can be accurately positioned, the four-way shuttle vehicle can be driven to adjust to a proper position, and the tray goods can be properly lifted and transported.

Description

TECHNICAL FIELD

[0001] The present application relates to the field of intelligent warehousing equipment, in particular to a four-way shuttle vehicle and a method for positioning a hollow tray thereof. BACKGROUND

[0002] In the existing warehousing system, a hollow tray is used to carry goods. The bottom plate of the hollow tray has a hollow structure. When a common point-shaped linear photoelectric sensor detects the position of the tray, the light will pass through the hollow structure, resulting in an inaccurate detection of the position of the tray.

[0003] During the warehousing process, the tray is often directly placed at the receiving point of the four-way shuttle vehicle by manual operation. The manual handling operation inevitably causes a front-back deviation in the coordinate position where the tray is placed. Therefore, only relying on the real-time running position of the four-way shuttle vehicle to perform the lifting and handling of the tray will cause a large deviation. The tray often cannot match the coordinate position where the lifting and handling of the four-way shuttle vehicle is performed due to the deviation in the placement position. At this time, the lifting action of the four-way shuttle vehicle will cause the tray to be partially lifted, thereby easily causing the tray to overturn.

[0004] For a fully automatic intelligent warehousing system, even if it has adopted a conveying automatic docking device for tray placement, the control error of the system and the slip generated when the tray stops will still cause the tray to fail to accurately reach the position directly above the expected lifting and loading position of the four-way shuttle vehicle. The front-back position deviation formed between the two will still cause the mobile automatic docking device such as the four-way shuttle vehicle to fail to stably carry the tray goods due to the positioning accuracy problem. The deviation in the goods receiving docking position will cause the tray to be unevenly stressed during the lifting and handling of the device, resulting in unstable center of gravity of the tray, and further causing the goods to overturn or the device to be blocked.

[0005] At this time, the four-way shuttle vehicle directly lifts the goods, which may directly trigger an alarm, resulting in an incorrect implementation of the goods taking. When the four-way shuttle vehicle reaches the edge position of the tray leg through photoelectric detection, even if it can normally lift the goods, due to the deviation in the positioning of the center of gravity of the tray, the photoelectric detection state is still easily changed by the shift of the center of gravity of the tray during the subsequent running process, thereby triggering an alarm for the deviation of the tray position. SUMMARY

[0006] The present application provides a four-way shuttle vehicle and a method for positioning a hollow tray thereof to solve the problems in the prior art. The present application is arranged with a plurality of pairs of linear photoelectric sensors at the edge of the body of the four-way shuttle vehicle. Thus, the present application can realize the recognition and positioning of the edge structure of the tray leg through the photoelectric detection signals in different directions of each pair of linear photoelectric sensors, further accurately position the actual position of the hollow tray, and drive the four-way shuttle vehicle to adjust to the appropriate position to properly implement the lifting and handling of the tray goods. The present application specifically adopts the following technical solutions.

[0007] First, to achieve the above objectives, a four-way shuttle is proposed, wherein several pairs of linear photoelectric sensors are arranged along the edge of the vehicle body, and the linear photoelectric sensors are arranged at least on opposite sides of the four-way shuttle; in each pair of linear photoelectric sensors, the interval between the light emission positions detected by the linear photoelectric sensors is less than the width of the pallet leg edge, and the emission direction of the light detected by the linear photoelectric sensors is set to be parallel to the lifting direction of the cargo lifting frame of the four-way shuttle.

[0008] Optionally, in any of the four-way shuttles described above, in each pair of linear photoelectric sensors, the position of the light emission detected by the linear photoelectric sensor is 1 cm away from the bottom edge of the tray leg; the light emission direction detected by the linear photoelectric sensor is upward and parallel to the longitudinal axis of the tray leg.

[0009] Optionally, in any of the four-way shuttles described above, at least one linear photoelectric sensor is disposed on the front side of the four-way shuttle in the direction of travel toward the fixed point of the target tray, and at least one linear photoelectric sensor is disposed on the rear side of the four-way shuttle in the direction of travel toward the fixed point of the target tray.

[0010] Meanwhile, to achieve the above objectives, this application also provides a method for positioning a hollowed-out pallet for a four-way shuttle as described above, the steps of which include: after the four-way shuttle runs to a fixed point on the shelf corresponding to the target pallet, triggering a linear photoelectric sensor to emit detection light; determining the target offset direction corresponding to the pallet based on the detection light of each pair of linear photoelectric sensors on the pallet legs; triggering the execution of a pallet alignment process corresponding to the target offset direction based on the target offset direction; and lifting and picking up the goods after the detection light of each pair of linear photoelectric sensors is aligned with the pallet legs.

[0011] Optionally, as described in any of the above methods, the step of determining the target offset direction corresponding to the tray based on the detection light of the tray legs by each pair of linear photoelectric sensors specifically includes: when the linear photoelectric sensors on the four-way shuttle body detect the reflection signal of the tray legs while the other linear photoelectric sensors do not detect the reflection signal of the tray legs, the target offset direction is determined to be from the linear photoelectric sensors that have not detected the reflection signal of the tray legs to the linear photoelectric sensors that have detected the reflection signal of the tray legs.

[0012] Optionally, as described in any of the above methods, the process of triggering the pallet alignment process corresponding to the target offset direction includes: driving the four-way shuttle to run in the target offset direction until all linear photoelectric sensors on one side of the four-way shuttle corresponding to the target offset direction detect the reflection signal of the pallet leg, triggering the recording of the detection position of the pallet leg edge; driving the four-way shuttle to continue running along the target offset direction until the detection positions of all linear photoelectric sensors are equidistant from the pallet leg edge.

[0013] Optionally, as described in any of the above methods, if all the linear photoelectric sensors on the side of the four-way shuttle corresponding to the target offset direction fail to detect the reflected signal of the tray leg within a preset offset range during the process of driving the four-way shuttle to move in the target offset direction, it is determined that the four-way shuttle is running out of range and an error is triggered.

[0014] Optionally, as described in any of the above methods, when all linear photoelectric sensors detect the reflected signal of the tray leg, triggering the recording of the detection position of the tray leg edge, and then continuing to drive the four-way shuttle along the target offset direction, if the four-way shuttle cannot make the detection positions of all linear photoelectric sensors equal to the distance from the tray leg edge within the preset offset range, then it is determined that the four-way shuttle is running out of range and an error is triggered.

[0015] Optionally, as described in any of the above methods, the preset offset range is: a range of 10cm before and after the starting position of the four-way shuttle when the alignment process is triggered. Beneficial effects

[0016] The four-way shuttle and its positioning method for the perforated pallet provided in this application involve arranging several pairs of linear photoelectric sensors along the edge of the shuttle's body. The distance between the light emission positions detected by each pair of linear photoelectric sensors is less than the width of the pallet leg edge. Therefore, this application can position the four-way shuttle by detecting the distance of the light relative to the pallet leg edge using the linear photoelectric sensors. This ensures that when lifting the pallet, the four-way shuttle is directly facing the bottom of the goods, maintaining the stable lifting of the goods on the pallet and preventing tipping or jamming during transportation. The detection mechanism of this application is simple, directly utilizing existing linear photoelectric sensors, which are installed at specific locations on the vehicle body to achieve detection and positioning, thereby accurately locating the actual position of the perforated pallet and driving the four-way shuttle to adjust to the appropriate position, effectively lifting and transporting the palletized goods.

[0017] Other features and advantages of this application will be set forth in the following description, and will be apparent in part from the description, or may be learned by practicing this application. Attached Figure Description

[0018] The accompanying drawings are provided to further illustrate the present application and form part of the specification. Together with the embodiments of the present application, they serve to explain the present application but do not constitute a limitation thereof. In the drawings:

[0019] Figure 1 This is a top view of the four-way shuttle structure of this application;

[0020] Figure 2 This is a side view of the four-way shuttle vehicle after aligning with the position of the hollowed-out tray in this application;

[0021] Figure 3 This is a schematic diagram of the positioning detection position of the hollowed-out tray detected by the linear photoelectric sensor group in the four-way shuttle of this application;

[0022] Figure 4 This is a schematic diagram of the overall steps of the method for positioning the hollowed-out tray provided in this application;

[0023] Figure 5 This is a flowchart illustrating the process of determining the tray position in the method of this application;

[0024] Figure 6 This is a flowchart illustrating the process of locating the tray position in the method described in this application.

[0025] In the diagram, 1 represents a fixed point; 2 represents the target pallet; 3 represents a four-way shuttle; and 4 represents the pallet leg. Implementation

[0026] To make the objectives and technical solutions of the embodiments of this application clearer, the technical solutions of the embodiments of this application will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some, not all, of the embodiments of this application. All other embodiments obtained by those skilled in the art based on the described embodiments of this application without creative effort are within the scope of protection of this application.

[0027] Those skilled in the art will understand that, unless otherwise defined, all terms used herein (including technical and scientific terms) have the same meaning as commonly understood by one of ordinary skill in the art to which this application pertains. It should also be understood that terms such as those defined in general dictionaries should be understood to have the same meaning as in the context of the prior art, and should not be interpreted in an idealized or overly formal sense unless defined as herein.

[0028] The meaning of "and / or" as used in this application includes situations where each exists alone or both exist simultaneously.

[0029] The terms "inside" and "outside" as used in this application refer to directions pointing inwards from the four-way shuttle vehicle itself, with "inside" being the direction pointing outwards and "outside" being the direction pointing inwards; rather than being a specific limitation on the device mechanism of this application.

[0030] The terms "left" and "right" as used in this application refer to the user's left side and right side when facing the direction of travel of the four-way shuttle, and do not constitute a specific limitation on the device mechanism of this application.

[0031] The term "connection" as used in this application can mean a direct connection between components or an indirect connection between components through other components.

[0032] The terms "up" and "down" as used in this application refer to the direction from which the track system points to the pallet on top of the cargo lifting frame when the user is facing the direction of travel of the four-way shuttle, and vice versa, rather than a specific limitation on the device mechanism of this application.

[0033] Figure 1 According to this application, a four-way shuttle is provided with a plurality of pairs of linear photoelectric sensors arranged at the edge of the vehicle body, wherein the linear photoelectric sensors are arranged at least on opposite sides of the four-way shuttle to monitor the positional relationship between the two sides of the vehicle body and the target tray through photoelectric signals.

[0034] In each pair of linear photoelectric sensors on each side of the vehicle body, the interval between the light emission positions detected by the linear photoelectric sensors can be referenced. Figure 2 The settings shown are smaller than the width of the pallet leg edge, and the emission direction of the light detected by the linear photoelectric sensor is set to be parallel to the lifting direction of the four-way shuttle cargo lifting frame.

[0035] Therefore, when the four-way shuttle reaches the target tray, it can... Figure 2 The method shown utilizes the reflected signals from the pallet legs of linear photoelectric sensors to calibrate the actual position of the pallet: Since the interval between the emission positions of the light emitted by the linear photoelectric sensors is smaller than the width of the pallet leg edge, when the light emitted by each linear photoelectric sensor is reflected by the pallet leg, causing its detection signal to be marked as "1", it can be determined that the linear photoelectric sensor has reached the bottom of the pallet leg. At this time, by calculating and recording the distance that the four-way shuttle continues to travel from the edge of the pallet leg to the middle of the pallet leg, the distance between the linear photoelectric sensors and the width of the pallet leg can be compared to ensure that the detection light of the four-way shuttle can be stably positioned at the center of the pallet leg, thereby ensuring that the goods pallet can be stably lifted and the handling can be stably achieved.

[0036] Considering that there is a certain calculation error when converting the rotation data of the four-way shuttle's driving wheels into the real-time position of the four-way shuttle after detecting the edge position of the pallet leg by the linear photoelectric sensor, in this application, based on the width of the pallet leg, a detection distance of 1cm is reserved between the light emission position detected by the linear photoelectric sensor and the bottom edge of the pallet leg, so as to reduce the detection error of the real-time position of the four-way shuttle.

[0037] To avoid angular deviation between the detected photoelectric signal and the position of the tray leg edge, this application generally uses a linear photoelectric sensor to detect light emission direction that is upward and parallel to the longitudinal axis of the tray leg.

[0038] Figure 3 This application illustrates several scenarios where the four-way shuttle aligns with a target pallet for pickup. The four-way shuttle operates on a crisscrossing track system. Pallets can be placed at specific locations on the track system by a forklift, lifting device, or manually, i.e., fixed point 1 marked in the figure. During the process of the four-way shuttle retrieving goods from the pallet along the track, its stopping position is determined by a coordinate marker or RFID tag within the rack. If the forklift or other equipment deviates from the position of the coordinate marker or RFID tag when placing the pallet, a positioning deviation will occur when the four-way shuttle retrieves the goods based on the coordinate marker or RFID tag, causing the pallet's position relative to the shuttle to shift vertically. Figure 3 (as shown in the direction) shifts. This means that even though the four-way shuttle can still lift and raise the pallet, after retrieval, the pallet will not be securely positioned at the shuttle's center of gravity; the pallet's center of gravity relative to the shuttle's center of gravity will shift vertically (up or down). Figure 3 (As shown in the direction) offset. At this point, when the four-way shuttle needs to switch to the left or right track to move goods, the left and right sides of the goods will collide with the rack due to the positional deviation between the goods and the four-way shuttle. This can easily cause goods to tip over or the four-way shuttle to malfunction, requiring manual adjustment, or the four-way shuttle needs to be driven to its normal positioning point to find the pallet position for adjustment.

[0039] The deviation between the actual position of the aforementioned cargo pallet and the fixed point corresponding to the target pallet can be automatically corrected through the steps outlined in this application. This ensures that the four-way shuttle can still correctly operate under the pallet even when the pallet's position deviates, thereby reliably lifting the goods for safe transport within the rack. The steps are as follows: Figure 4 Set to:

[0040] After the four-way shuttle 3 runs to the fixed point 1 on the shelf corresponding to the target pallet, it triggers the linear photoelectric sensors Q1, Q2, Q3, Q4, etc. to emit detection light respectively;

[0041] Based on the detection light of each pair of linear photoelectric sensors on the tray legs, it is determined whether the corresponding linear photoelectric sensor has reached the bottom of the tray legs, and then the target offset direction corresponding to the tray is determined by the detection status between the linear photoelectric sensors.

[0042] The pallet alignment process corresponding to the target offset direction is triggered based on the target offset direction;

[0043] After the detection beams of each pair of linear photoelectric sensors are aligned with the pallet legs, the pallet is lifted to retrieve the goods.

[0044] Specifically, since the retrieval of pallets by the four-way shuttle in the smart warehouse only occurs on a track in a fixed direction, this application can directly set linear photoelectric sensors on the left and right sides of the four-way shuttle along the direction of the goods retrieval track. Each side can be equipped with a pair of linear photoelectric sensors with a spacing slightly smaller than the width of the pallet legs. Therefore, after the four-way shuttle 3 runs to the fixed point 1 on the shelf corresponding to the target pallet, it triggers the linear photoelectric sensor to emit detection light. When the linear photoelectric sensor on the body of the four-way shuttle detects the reflection signal of the pallet leg while the other linear photoelectric sensors do not detect the reflection signal of the pallet leg, it is determined that the target offset direction is from the linear photoelectric sensor that did not detect the reflection signal of the pallet leg to the linear photoelectric sensor that did detect the reflection signal of the pallet leg. Then, according to the target offset direction, the four-way shuttle is further driven to run in the target offset direction until all the linear photoelectric sensors on the side of the four-way shuttle corresponding to the target offset direction have detected the reflection signal of the pallet leg. At this time, the detection position of the pallet leg edge is recorded. At the same time, the four-way shuttle is further driven to continue running in the target offset direction until the detection position of all linear photoelectric sensors is equidistant from the pallet leg edge. When it is confirmed that the detection light of each pair of linear photoelectric sensors is aligned with the pallet leg, the operation of the four-way shuttle is stopped, and the lifting and picking action is performed.

[0045] The above driving steps can be broken down into: Figure 5 , Figure 6 The images show the situations where the bottom of the pallet is cheaper and the top of the pallet is cheaper, respectively.

[0046] Reference Figure 3 In the first row, under normal procedures, the pallet moves towards the positioning position of the four-way shuttle. When the pallet itself is already aligned with the positioning position of the four-way shuttle, that is, at fixed point 1, the four-way shuttle can align the pallet and lift it to retrieve the goods according to the following steps:

[0047] Step a1: Drive the four-way shuttle to move to the four-way shuttle positioning position;

[0048] Step a2: The four-way shuttle is accurately moved to the four-way shuttle positioning position;

[0049] Step a3: Trigger the photoelectric sensors Q1 / Q2 / Q3 / Q4 of the four-way shuttle to emit photoelectric detection signals. When it is determined from the reflected signals that each photoelectric sensor can detect the middle leg of the pallet, lift the vehicle to retrieve the goods.

[0050] Reference Figure 3 In the middle row, when the pallet itself is positioned slightly above the four-way shuttle's location as shown in the diagram, the four-way shuttle can reach the pallet and lift it to retrieve the goods by following these steps:

[0051] Step b1: The four-way shuttle moves to the fixed point 1 corresponding to the pallet. At this time, the four-way shuttle is located slightly below the pallet.

[0052] Step b2: The four-way shuttle triggers each linear photoelectric sensor Q1 / Q2 / Q3 / Q4 to emit photoelectric detection signals, and then judges based on their reflected signals: the linear photoelectric sensor Q1 / Q2 located on the front side of the vehicle's running direction can detect the pallet leg, while the Q3 / Q4 located on the rear side of the vehicle's running direction cannot detect it, the pallet is offset, and the pallet search is started.

[0053] Step b3: The four-way shuttle continues to move in its original direction, moving upwards to locate the pallet. Based on the detection signals from each linear photoelectric sensor (Q1 / Q2 / Q3 / Q4), it is determined that the pallet edge has been found when the middle leg of the pallet is detected. At this point, the four-way shuttle continues to move a distance x in its original direction based on this positioning position, then stops, triggering the lifting and retrieval of the pallet. The distance x is generally set to no more than (pallet leg width - distance between adjacent linear photoelectric sensors) * 1 / 2. This ensures that the four-way shuttle runs precisely to the position where the linear photoelectric sensor aligns with the middle of the pallet leg, maximizing the alignment of the four-way shuttle with the pallet directly below it during the lifting operation.

[0054] Reference Figure 3 At the bottom, when the pallet itself is positioned slightly lower than the four-way shuttle's location as shown in the diagram, the four-way shuttle can locate the pallet and lift it to retrieve the goods by following these steps:

[0055] Step c1: The four-way shuttle moves to the fixed point 1 corresponding to the pallet. At this time, the four-way shuttle is located slightly above the pallet.

[0056] In step c2, the four-way shuttle triggers each linear photoelectric sensor Q1 / Q2 / Q3 / Q4 to emit photoelectric detection signals, and then judges based on their reflected signals: the linear photoelectric sensor Q3 / Q4 located on the rear side of the vehicle's running direction can detect the pallet leg, while the Q1 / Q2 located on the front side of the vehicle's running direction cannot detect it, the pallet is offset, and the pallet search is started.

[0057] In step c3, the four-way shuttle continues its return along its original direction of travel, moving downwards to locate the pallet. Based on the detection signals from each linear photoelectric sensor, it is determined that the pallet edge has been found when Q1 / Q2 / Q3 / Q4 all detect the middle leg of the pallet. At this point, the four-way shuttle continues to travel a distance x along the pallet-finding direction until it stops, triggering the lifting and retrieval of the pallet. The distance x is generally set to no more than (pallet leg width - distance between adjacent linear photoelectric sensors) * 1 / 2. This ensures that the four-way shuttle travels precisely to the position where the linear photoelectric sensors align with the middle of the pallet leg, maximizing the alignment of the four-way shuttle directly beneath the pallet during the lifting operation.

[0058] In the above process, refer to Figure 6 As shown in the intermediate process, if, during the process of starting the pallet-finding process after determining that the pallet has shifted, all the linear photoelectric sensors on the side of the four-way shuttle corresponding to the target shift direction are within the preset shift range, for example, within a 10cm range before and after the position of the four-way shuttle when the alignment process is triggered, and they still cannot detect the reflection signal of the pallet leg, then it is determined that the four-way shuttle is running out of range and an error is triggered.

[0059] Similarly, as each linear photoelectric sensor Q1 / Q2 / Q3 / Q4 detects the middle leg of the tray, determines that the tray edge has been found, and continues to drive the four-way shuttle a distance x based on this positioning position, the distance x traveled by the four-way shuttle can also be determined in real time by detecting the distance from the detection position of each linear photoelectric sensor to the edge of the tray leg. In this method, if the four-way shuttle cannot make the detection positions of all linear photoelectric sensors equal to the edge of the tray leg within a preset offset range, for example, within a 10cm range before and after the starting position of the four-way shuttle when the alignment process is triggered, then it is determined that the four-way shuttle is running out of range, triggering an error.

[0060] The above are merely embodiments of this application, and their descriptions are quite specific and detailed, but they should not be construed as limiting the scope of this patent application. It should be noted that those skilled in the art can make various modifications and improvements without departing from the concept of this application, and these all fall within the protection scope of this application.

Claims

1. A four-way shuttle vehicle, characterized in that, This is used to lift and transport goods on a hollow pallet, wherein the hollow pallet has a hollow structure on its bottom plate; The four-way shuttle has several pairs of linear photoelectric sensors arranged along its body edge. The linear photoelectric sensors are arranged at least on opposite sides of the four-way shuttle. The four-way shuttle uses photoelectric detection signals from different directions in each pair of linear photoelectric sensors to identify and locate the edge structure of the tray legs, thereby accurately locating the actual position of the hollow tray and driving the four-way shuttle to adjust to the appropriate position. In each pair of linear photoelectric sensors, the interval between the light emission positions detected by the linear photoelectric sensors is less than the width of the edge of the hollow pallet leg, and the emission direction of the light detected by the linear photoelectric sensors is set to be parallel to the lifting direction of the cargo lifting frame of the four-way shuttle. The linear photoelectric sensors are installed on the left and right sides of the four-way shuttle along the direction of the cargo retrieval track. Each side has a pair of linear photoelectric sensors, and the spacing between the pairs of linear photoelectric sensors is set to be less than the width of the hollowed-out pallet legs. After the four-way shuttle reaches the fixed point on the shelf corresponding to the target perforated pallet, the linear photoelectric sensor is triggered to emit detection light. When the linear photoelectric sensor on the four-way shuttle body detects the reflection signal of the perforated pallet leg, while the other linear photoelectric sensors do not detect the reflection signal, the target offset direction is determined to be from the linear photoelectric sensor that did not detect the reflection signal of the perforated pallet leg to the linear photoelectric sensor that did detect the reflection signal of the perforated pallet leg. Then, the four-way shuttle is further driven to move in the target offset direction until all the linear photoelectric sensors on the side of the four-way shuttle corresponding to the target offset direction have detected the reflection signal of the perforated pallet leg. At this time, the detection position of the edge of the perforated pallet leg is recorded. At the same time, the four-way shuttle is further driven to continue moving in the target offset direction until the detection position of all linear photoelectric sensors is equidistant from the edge of the perforated pallet leg. When it is confirmed that the detection light of each pair of linear photoelectric sensors is aligned with the perforated pallet leg, the driving of the four-way shuttle is stopped, and the lifting and picking action is performed.

2. The four-way shuttle as described in claim 1, characterized in that, In each pair of linear photoelectric sensors, a 1cm detection distance is reserved between the position of the light emission detected by the linear photoelectric sensor and the bottom edge of the hollow tray leg; The linear photoelectric sensor detects that the emitted light is upward and parallel to the longitudinal axis of the hollowed-out tray leg.

3. The four-way shuttle as described in claim 1, characterized in that, At least one linear photoelectric sensor is installed on the front side of the four-way shuttle in the direction of travel toward the fixed point of the target hollow tray, and at least one linear photoelectric sensor is installed on the rear side of the four-way shuttle in the direction of travel toward the fixed point of the target hollow tray.

4. A method for positioning a perforated tray, characterized in that, For the four-way shuttle vehicle according to any one of claims 1-3, the method for positioning the perforated tray includes the following steps: After the four-way shuttle reaches the fixed point on the shelf corresponding to the target hollowed-out pallet, it triggers the linear photoelectric sensor to emit detection light; The target offset direction corresponding to the hollowed-out tray is determined based on the detection light of each pair of linear photoelectric sensors on the hollowed-out tray legs; The process of aligning the hollowed-out pallets corresponding to the target offset direction is triggered based on the target offset direction; After the detection beams of each pair of linear photoelectric sensors are aligned with the hollowed-out pallet legs, the pallet is lifted to retrieve the goods.

5. The method for positioning a perforated tray as described in claim 4, characterized in that, The steps for determining the target offset direction corresponding to the hollowed-out tray based on the detection light rays of each pair of linear photoelectric sensors on the hollowed-out tray legs specifically include: When the linear photoelectric sensor on the body of the four-way shuttle detects the reflection signal of the hollowed-out tray leg while the other linear photoelectric sensors do not detect the reflection signal of the hollowed-out tray leg, the target offset direction is determined to be from the linear photoelectric sensor that did not detect the reflection signal of the hollowed-out tray leg to the linear photoelectric sensor that has detected the reflection signal of the hollowed-out tray leg.

6. The method for positioning a perforated tray as described in claim 4, characterized in that, The process of aligning the hollowed-out pallets according to the target offset direction is triggered, including: Drive the four-way shuttle to move in the direction of the target offset until all the linear photoelectric sensors on the side of the four-way shuttle corresponding to the target offset direction detect the reflected signal of the hollow tray leg, triggering the recording of the detection position of the edge of the hollow tray leg; The four-way shuttle continues to move along the target offset direction until all the detection positions of the linear photoelectric sensors are equidistant from the edge of the hollowed-out tray leg, at which point it stops.

7. The method for positioning a perforated tray as described in claim 6, characterized in that, If, during the process of driving the four-way shuttle to move in the direction of the target offset, all the linear photoelectric sensors on the side of the four-way shuttle corresponding to the target offset direction cannot detect the reflected signal of the hollow tray leg within the preset offset range, it is determined that the four-way shuttle is running out of range and an error is triggered.

8. The method for positioning a perforated tray as described in claim 7, characterized in that, When all linear photoelectric sensors detect the reflected signal from the hollowed-out tray leg, the detection position of the edge of the hollowed-out tray leg is recorded. During the process of driving the four-way shuttle to continue running along the target offset direction, if the four-way shuttle cannot make the detection position of all linear photoelectric sensors equal to the distance from the edge of the hollowed-out tray leg within the preset offset range, it is determined that the four-way shuttle is running out of range and an error is triggered.

9. The method for positioning a perforated tray as described in claim 7, characterized in that, The preset offset range is 10cm before and after the position of the four-way shuttle when the alignment process is triggered.

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