Express delivery robot with gravity descending layer replenishment function and control method thereof

Abstract

The application discloses a kind of express delivery robot with gravity descending layer replenishment function, including main body shell, perception navigation system, elevator interaction system, chassis walking system, push device, warehouse switch device, cargo detection device and control system.The main body shell is vertically provided with multiple layers of warehouses inside, and each layer of warehouse is divided into multiple independent warehouse units along the horizontal direction.The push device is arranged in the bottommost layer of warehouse unit, and can move bidirectionally along the horizontal direction to push the goods out from any side door.The warehouse switch device is used to open the bottom wall of each layer of warehouse unit.The application simplifies the internal vertical transport mechanism through gravity descending layer replenishment design, reduces cost and failure rate, and realizes compatible interaction with non-intelligent elevator through mechanical arm pressing elevator button, with strong adaptability.

Description

Technical Field

[0001] This invention relates to the field of logistics robot technology, specifically to a courier delivery robot with gravity-assisted de-leveling replenishment function and its control method. Background Technology

[0002] With the rapid development of e-commerce, the demand for last-mile delivery has increased dramatically. Traditional manual delivery methods suffer from low efficiency, high costs, and high labor intensity. In recent years, automated delivery robots have received widespread attention, as they can autonomously navigate to the target floor and the customer's door to complete the transportation and unloading of packages.

[0003] However, existing delivery robots still have the following drawbacks in practical applications: the warehouse structure is simple, usually with only a single layer or a small number of storage locations, making it impossible to efficiently manage multiple parcels within a limited volume. Some logistics robots with multi-layer warehouses use lifting mechanisms to transfer goods between different layers, but these lifting mechanisms occupy a large amount of space, have complex structures, and are costly. Summary of the Invention

[0004] To address the shortcomings of existing technologies, this application provides a delivery robot with gravity-assisted layer-drop replenishment functionality, comprising: The main shell has multiple layers of warehouses arranged vertically inside, and each layer of warehouses is divided into multiple independent warehouse units horizontally. The pushing device, located in the lowest level warehouse, is configured to move bidirectionally in the horizontal direction to push out goods located in the lowest level warehouse unit from either side of the warehouse door. Multiple warehouse switch devices are installed in each warehouse unit except the bottom layer, and are used to open the bottom wall of the corresponding warehouse unit; The cargo detection device is installed in the lowest-level warehouse unit to detect whether there are any goods in the warehouse unit. The chassis running system is used to drive the main body shell to move and steer; A perception and navigation system, mounted on the main body shell, is used for environmental perception and path planning; The control system is electrically connected to the pushing device, the warehouse switching device, the cargo detection device, the chassis walking system, and the sensing and navigation system. The control system is configured such that when the cargo detection device detects that the bottommost cargo unit is empty, the bottom walls of each cargo unit are opened layer by layer from the upper layer adjacent to the bottommost layer, so that the cargo in the upper layer falls to the bottommost layer. The opened bottom walls remain open until there is cargo in the bottommost cargo unit or all the upper cargo units are emptied.

[0005] Furthermore, it also includes a cargo identification device, which is installed at the warehouse door or on the cargo pushing device and is electrically connected to the control system, for reading the identification information of the cargo when the cargo is pushed out.

[0006] Furthermore, the multiple warehouse units are divided into bottom warehouse units and upper warehouse units. The bottom wall of the upper warehouse unit has an openable structure. The pushing device includes a drive motor located below the bottom warehouse unit. The output end of the drive motor is provided with a bidirectional lead screw or synchronous belt. A push plate is provided on the bidirectional lead screw or synchronous belt. A limiting groove is opened on the bottom wall of the bottom warehouse unit. The push plate can move bidirectionally within the range of the limiting groove, and the two sides of the push plate respectively form the bottom warehouse unit.

[0007] Furthermore, the pushing device also includes a push rod and pulleys. The push rod is connected to the top of the push plate, and the pulleys are respectively provided at both ends of the push rod. The pulleys can abut against the corresponding side of the compartment door.

[0008] Furthermore, the cargo compartment switching device is configured as an electromagnetic locking device, and the bottom wall of the upper cargo compartment is connected to the main body shell through the electromagnetic locking device.

[0009] Furthermore, the perception navigation system includes at least one lidar and at least one camera.

[0010] As another aspect of this application, a control method for the aforementioned express delivery robot is also provided, specifically including the following steps: Step S1: Generate a unique code for each express delivery to be delivered and establish a delivery task list. In the delivery task list, the unique code of each express delivery is associated with and stored with the following information: target delivery address, warehouse floor number, and warehouse unit number. Step S2: According to the delivery task list, control the express delivery robot to move to the current target delivery address, and use the cargo detection device to detect whether there are goods in the bottom warehouse unit; Step S3: If there are goods in the bottom warehouse unit, determine whether there is a target express delivery in the delivery task list that is at the bottom warehouse level and whose target delivery address is the current target delivery address; if there is, control the pushing device to push the target express delivery out of the corresponding warehouse door; during the pushing process, read the unique code of the express delivery through the goods identification device, and check whether the target delivery address of the express delivery is the current target delivery address. If so, the delivery is completed; otherwise, the delivery is stopped and an alarm signal is issued. Step S4: After delivery is completed in step S3, the cargo detection device checks again whether the bottom warehouse unit is empty, or if the bottom warehouse unit is detected to be empty in step S2, the layer-by-layer replenishment process is triggered: with the bottom as the first layer, the bottom walls of each warehouse unit are opened layer by layer from the second layer upwards, allowing the goods to fall to the lower layer; the already opened bottom walls remain open, and after each layer is opened, the bottom is checked to see if it is empty. If it is still empty, the next layer is opened until there are goods at the bottom or all the upper layers are cleared. Step S5: Update the warehouse floor number of the dropped package in the delivery task list to the bottom floor, and update its warehouse unit number. Step S6: Repeat steps S3 to S5 until all express deliveries corresponding to the current target delivery address have been delivered. Step S7: According to the delivery task list, control the express delivery robot to move to the next target delivery address, and repeat steps S2 to S6 until all express deliveries in the delivery task list have been delivered.

[0011] Furthermore, the multiple warehouse units are divided into three layers vertically, namely the first layer, the second layer, and the third layer, wherein the first layer is the bottommost warehouse unit; the layer-by-layer replenishment process in step S4 is specifically as follows: First, control the bottom wall of the second-level warehouse unit to open, so that the goods on the second level fall to the first level under the action of gravity. After the bottom wall of the second level is opened, keep it open. Subsequently, the cargo detection device checks whether the first layer is empty. If it is still empty, the bottom wall of the third layer warehouse unit is opened, allowing the cargo on the third layer to fall directly to the first layer warehouse unit under the action of gravity, passing through the already opened second layer warehouse unit. The bottom wall of the third layer remains open after it is opened.

[0012] Furthermore, in step S4, the step of detecting whether the lowest-level warehouse unit is in an empty state includes: The detection value is obtained by a pressure sensor or photoelectric sensor set at the bottom of the lowest storage unit. If the detection value is lower than a preset threshold, the lowest storage unit is determined to be in an empty state.

[0013] Furthermore, in step S2, the step of controlling the express delivery robot to move to the current target delivery address includes: Spatial modeling is performed using LiDAR, environmental perception is achieved using cameras, and the system autonomously plans its path and controls the movement of the chassis walking system. When the delivery robot moves to the elevator entrance of the target building, it also includes an elevator interaction step: the robot recognizes and presses the elevator button by the robotic arm set on the side of the main body shell, and controls the delivery robot to enter the elevator and reach the target floor.

[0014] The advantages of this application are: the provided express delivery robot, through its multi-layer, multi-unit warehouse design, enables the robot to handle multiple delivery tasks at once; the gravity-assisted layer-by-layer replenishment design utilizes gravity to automatically drop upper-layer goods to the bottom delivery position, eliminating the need for a complex vertical lifting mechanism, simplifying the internal structure, reducing manufacturing costs and maintenance failure rates; at the same time, the design of keeping the already opened bottom wall open allows upper-layer goods to fall directly to the bottom layer through the already opened middle layer, avoiding repeated opening and closing operations and improving replenishment efficiency. Attached Figure Description

[0015] Figure 1 A schematic diagram of a structural embodiment of the express delivery robot with gravity-assisted layer-drop replenishment function according to this application; Figure 2 for Figure 1 Another perspective structural diagram; Figure 3 for Figure 2 A schematic diagram showing the connection between the bottom wall of the central warehouse unit and the electromagnetic locking device.

[0016] Figure 4 for Figure 2 Schematic diagram of the central pushing device; Figure 5 for Figure 4 Schematic diagram of a partial structure; Figure 6 This is a flowchart of the express delivery robot control method of this application. Detailed Implementation

[0017] To enable those skilled in the art to better understand the present application, the technical solutions in the embodiments of the present application will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present application, and not all embodiments. Based on the embodiments in the present application, all other embodiments obtained by those of ordinary skill in the art without creative effort should fall within the scope of protection of the present application.

[0018] It should be noted that the terms "first," "second," etc., in the specification, claims, and accompanying drawings of this application are used to distinguish similar objects and are not necessarily used to describe a specific order or sequence. It should be understood that such data can be interchanged where appropriate for the embodiments of this application described herein. Furthermore, the terms "comprising" and "having," and any variations thereof, are intended to cover non-exclusive inclusion; for example, a process, method, system, product, or apparatus that comprises a series of steps or units is not necessarily limited to those steps or units explicitly listed, but may include other steps or units not explicitly listed or inherent to such processes, methods, products, or apparatus.

[0019] In this application, the terms "upper," "lower," "left," "right," "front," "rear," "top," "bottom," "inner," "outer," "middle," "vertical," "horizontal," "lateral," and "longitudinal" indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings. These terms are primarily for the purpose of better describing this application and its embodiments, and are not intended to limit the indicated device, element, or component to having a specific orientation, or to be constructed and operated in a specific orientation.

[0020] Furthermore, in addition to indicating location or positional relationship, some of the aforementioned terms may also have other meanings. For example, the term "above" may also be used in some cases to indicate a certain dependency or connection relationship. Those skilled in the art can understand the specific meaning of these terms in this application based on the specific circumstances.

[0021] Furthermore, the terms "installation," "setup," "equipped with," "connection," "linking," and "socketing" should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral structure; they can refer to a mechanical connection or an electrical connection; they can refer to a direct connection or an indirect connection through an intermediate medium, or an internal connection between two devices, components, or parts. Those skilled in the art can understand the specific meaning of these terms in this application based on the specific circumstances.

[0022] It should be noted that, unless otherwise specified, the embodiments and features described in this application can be combined with each other. This application will now be described in detail with reference to the accompanying drawings and embodiments. Example 1

[0023] See Figures 1-5This embodiment provides a courier delivery robot with gravity-assisted layer-by-layer replenishment function. Specifically, it includes a main body shell 10, which is the basic load-bearing structure of the robot. Inside, there are multiple layers of cargo compartments arranged vertically. In this embodiment, the cargo compartments are divided into three layers, and each layer is divided into four independent cargo compartment units horizontally, for a total of twelve cargo compartment units. Each cargo compartment unit can hold one large item or multiple small items. Of course, the number of layers and the number of units per layer can be adjusted according to actual needs.

[0024] A chassis-mounted walking system 20 is installed beneath the main body shell to drive the robot's movement and steering. In this embodiment, the chassis-mounted walking system is driven by dual steering wheels 21, in conjunction with four balancing auxiliary wheels 22, to achieve zero-radius steering and stable movement. The dual steering wheel drive allows the robot to turn flexibly in narrow corridors and elevators, while the four balancing auxiliary wheels ensure the robot's stability during movement and delivery, preventing tipping due to uneven weight distribution of goods.

[0025] The main body shell is also equipped with a perception and navigation system for environmental perception and path planning. In this embodiment, the perception and navigation system includes a lidar 12 set on the top of the main body shell and multiple cameras 13 set around the main body shell. The lidar is used to perform spatial modeling of the surrounding environment and generate a three-dimensional point cloud map; the cameras are used for environmental perception and to identify key targets such as obstacles, house numbers, and elevator entrances. The lidar and cameras work together to enable the robot to autonomously plan its path and avoid obstacles in real time.

[0026] The delivery robot also includes an elevator interaction system, including a robotic arm 14 mounted on the main body shell 10. The robotic arm 14 is equipped with a touch rod 15. The robotic arm can be a multi-degree-of-freedom articulated robotic arm with at least two rotational degrees of freedom, enabling it to move flexibly in three-dimensional space to press elevator buttons at different heights and positions. At the same time, a miniature camera (not shown in the figure) is also installed on the robotic arm to identify the position of the elevator buttons.

[0027] More specifically, the main shell 10 is divided into two areas by a first vertical partition 11. Each area has three layers of warehouses arranged vertically. The three layers of warehouses are divided into a bottom warehouse (first layer warehouse 102) and an upper warehouse. The upper warehouses are the second layer warehouse 103 and the third layer warehouse 104. The second layer warehouse 103 and the third layer warehouse 104 are each divided into two independent upper warehouse units 1031 by a second vertical partition 105. The bottom wall of each upper warehouse unit is composed of an independent horizontal partition 106.

[0028] Specifically, one side of the horizontal partition 106 of each upper warehouse unit is rotatably connected to the first vertical partition 11 via a hinge 107 and a first crossbeam 108, and the other side is connected to the second crossbeam 109 via a warehouse switch device 16. The two ends of the second crossbeam are connected to the main body shell 10. The warehouse switch device 16 is constructed as an electromagnetic locking device. When the electromagnetic locking device is energized, it generates magnetic force to attract and fix the bottom wall in a closed state. When the power is off, the magnetic force disappears, and the bottom wall opens under its own gravity, allowing the goods to fall.

[0029] In addition, main body doors 17 are provided on both sides of the main body shell 10. When opened, they can be used to place express packages in the twelve warehouse units, and can also be used to manually close the bottom wall of the upper warehouse unit. Unloading doors 18 are provided on both sides of the first warehouse 102. The top of the unloading door 18 is also connected to the main body shell by a hinge, which makes it easy for the pushing device to push the goods out of any door. In order to prevent the door from being opened during the robot's movement, a magnetic suction device (not shown in the figure) is provided at the bottom for fixing.

[0030] In order to push out the goods, a pushing device 30 is provided in the bottom warehouse, i.e. the first warehouse 102. The pushing device 30 includes a pushing motor 31 located below the bottom warehouse unit. A synchronous belt 32 is provided at the output end of the pushing motor 31. A push plate 33 is fixedly installed on the synchronous belt 32. A limiting groove 1021 is opened on the bottom wall of the bottom warehouse unit. The push plate 33 extends upward through the limiting groove into the warehouse unit, and the push plate can move bidirectionally within the range of the limiting groove.

[0031] The push plate forms independent bottom storage units 1022 on both sides. That is, the push plate divides the bottom storage unit into two independent storage areas, corresponding to the unloading doors on both sides. In the initial state, the push plate is located in the middle of the first storage layer, and the bottom storage units on both sides are the same size as the upper storage units above. Of course, the position of the push plate can be adjusted to change the size of the bottom storage units, thereby adapting to the size of different goods and facilitating the placement of large goods.

[0032] When the pusher motor 31 rotates in the forward direction, the synchronous belt drives the pusher plate to move to one side, pushing the goods located on that side of the pusher plate out of the corresponding side's door. When the pusher motor rotates in the reverse direction, the synchronous belt drives the pusher plate to move to the other side, pushing the goods located on the other side of the pusher plate out of the other side's door, thus realizing the bidirectional pusher function. Of course, the bidirectional transmission mechanism can use a bidirectional lead screw instead of the synchronous belt. The bidirectional lead screw is equipped with a lead screw nut connected to the pusher plate. The pusher motor drives the bidirectional lead screw to rotate, and the lead screw nut converts the rotational motion into the linear reciprocating motion of the pusher plate.

[0033] A push rod 34 is provided at the top of the push plate 33. The push rod 34 extends to both sides along the push plate and moves with the push plate. Pulleys 35 are provided at both ends of the push rod 34, and the pulleys 35 can abut against the inner side of the corresponding side of the compartment door. When the push plate moves to one side, the pulley on the same side as the push rod first contacts the inner side of the compartment door on that side. As the push plate continues to move, the pulley rolls on the inner side of the compartment door and pushes the compartment door open. Since the friction between the pulley and the compartment door is rolling, it can effectively prevent the mechanical mechanism from scratching the inner side of the compartment door and extend the service life of the equipment.

[0034] Each bottom-level warehouse unit 1021 is also equipped with a cargo detection device to detect whether there is cargo in the warehouse unit. In this embodiment, the cargo detection device adopts a pressure sensor or photoelectric sensor installed at the bottom of the bottom-level warehouse unit. When the detected value is lower than a preset threshold, the bottom-level warehouse unit is determined to be empty.

[0035] The express delivery robot of this application also includes a control system, which is electrically connected to a pushing device, a warehouse switching device, a cargo detection device, a chassis walking system, a perception and navigation system, and an elevator interaction system. Example 2

[0036] This embodiment provides a control method for the above-mentioned express delivery robot with gravity-assisted layer-drop replenishment function, such as... Figure 6 As shown, the specific steps include: Step S1: Create a delivery task list Before the delivery robot departs, the control system receives delivery task data from the dispatch center. A unique code is generated for each package to be delivered (e.g., a QR code, RFID tag, or barcode can be used to carry this unique code), and a delivery task list is established. In this delivery task list, the unique code for each package is associated with and stores the following information: the target delivery address (including building number, unit number, floor number, room number, etc.), the warehouse floor number (e.g., first, second, or third floor), and the warehouse unit number (e.g., left or right unit within the same floor).

[0037] According to the delivery task list, the operator places each express package into the corresponding warehouse unit in sequence and confirms the loading is completed in the control system. After loading is completed, the control system records the correspondence between the unique code of each express package in the warehouse unit and the warehouse location.

[0038] Step S2: Navigation Movement and Target Positioning The control system, based on the delivery task list and following a preset delivery order (e.g., from floor to floor or according to the order determined by a path optimization algorithm), controls the delivery robot to move to the current target delivery address. Specifically, this includes the following sub-steps: Step S2.1: Environmental Perception and Path Planning A LiDAR scanner mounted on the top of the main body scans the surrounding environment to generate a 3D point cloud map, enabling spatial modeling. Multiple cameras positioned around the main body perceive the environment, identifying obstacles, door numbers, stairwells, and other key targets. The LiDAR and cameras work collaboratively, fusing data from multiple sensors, allowing the robot to autonomously plan its path and avoid obstacles in real time. The control system generates the optimal path from the current location to the target delivery address based on the perceived data and controls the chassis's walking system to move along that path.

[0039] Step S2.2: Elevator Interaction When the delivery robot moves to the elevator entrance of the target building, it triggers the elevator interaction process. The control system identifies the location of the floor buttons on the elevator panel using a camera, and then controls the movement of the robotic arm mounted on the side of the main body. The robotic arm adopts a multi-degree-of-freedom articulated design (with at least two rotational degrees of freedom), and its end effector is equipped with a contact rod. The robotic arm moves flexibly in three-dimensional space, precisely aligning the contact rod with the target floor button and pressing it. After pressing, the control system confirms whether the button has been pressed using a camera; if not, it repeats the pressing operation. After the elevator arrives, the control system controls the robot to enter the elevator and, after reaching the target floor, controls the robot to exit the elevator.

[0040] Step S2.3: Arrive at the target delivery address After reaching the target floor, the robot continues to move along the planned path to the target delivery address (such as the door of a specific room). Upon arrival, it uses a cargo detection device to check whether the ground floor warehouse unit contains goods.

[0041] Step S3: Cargo Inspection and Delivery If there are goods in the bottom warehouse unit, the control system determines whether there is a target express delivery in the delivery task list that is located at the bottom layer (i.e., the first layer) and has the target delivery address as the current target delivery address.

[0042] If a target package is present, the control system controls the pushing device to push the package out of the corresponding side door. Specifically: if the target package is located in the left area of ​​the bottom storage unit, the control system controls the pushing motor to rotate forward, driving the push plate to move to the left, pushing the goods in the left area out of the left door; if the target package is located in the right area of ​​the bottom storage unit, the control system controls the pushing motor to rotate in reverse, driving the push plate to move to the right, pushing the goods in the right area out of the right door. During the movement of the push plate, the push rod at the top of the push plate moves along with it. The pulley at the end of the push rod first abuts against the inside of the corresponding side door. As the push plate continues to move, the pulley rolls inside the door and pushes the door open, thus completing the push of the goods.

[0043] During the goods pushing process, a goods identification device (such as a QR code scanner or RFID reader) installed at the warehouse door or on the pushing device reads the unique code of the package. The control system compares this unique code with the unique code of the package corresponding to the current target delivery address in the delivery task list. If they match, the delivery is confirmed as complete, and the control system records that the package has been delivered; if they do not match, the delivery is stopped and an alarm signal is issued (such as through an audible and visual alarm or by sending an alarm message to the dispatch center) to prevent misdelivery of packages.

[0044] Step S4: Layer-by-layer replenishment process After delivery is completed in step S3, the control system checks again whether the bottom-level warehouse unit is empty using the cargo detection device. If it is empty, the layer-by-layer replenishment process is triggered, as follows: Starting with the bottom layer as layer 1, the bottom walls of each storage unit are opened sequentially upwards from layer 2, allowing goods from the upper layers to fall to the lower layers under gravity. Opened bottom walls remain open and are not closed. After each layer is opened, the control system uses a cargo detection device to check if the bottom layer is empty: if it is still empty, the next layer is opened; if there are goods on the bottom layer, opening the next layer stops; if all upper storage units have been emptied (i.e., all upper layers are open and no goods have fallen to the bottom layer), the replenishment process stops.

[0045] Taking the three-layer warehouse in this embodiment as an example, the replenishment process layer by layer is as follows: First, the control system de-energizes the electromagnetic locking device of the second (middle) storage unit. After the magnetic force disappears, the bottom wall of the second layer rotates and opens around the hinge under its own gravity. The goods in the second storage unit fall to the first layer (bottom layer) under gravity. After the bottom wall of the second layer opens, it remains open and does not close again.

[0046] Subsequently, the control system obtains the detection value through the cargo detection device (such as a pressure sensor or photoelectric sensor) set at the bottom of the lowest cargo unit. If the detection value is lower than the preset threshold (for example, the pressure value detected by the pressure sensor is lower than the reference value when empty, or the photoelectric sensor detects that there is no cargo blocking it), it is determined that the lowest cargo unit is still empty.

[0047] If the bottom layer is determined to be empty, the control system de-energizes the electromagnetic locking device of the third (top) storage unit. The bottom wall of the third layer opens under its own gravity, and the goods inside the third storage unit fall through the already open second storage unit and directly to the first storage unit. The bottom wall of the third layer remains open after opening.

[0048] The "open bottom wall remains open" design allows upper-level goods to fall directly to the bottom layer through the opened middle layer, avoiding the tedious operation of repeatedly opening and closing the bottom wall and improving replenishment efficiency.

[0049] Step S5: Update the delivery task list After the layer-by-layer replenishment process is completed, the control system updates the package information in the delivery task list that has changed location. Specifically: the "warehouse layer number" of packages that have fallen and are finally located in the bottom warehouse unit is updated to the bottom layer (layer 1), and its "warehouse unit number" (such as the left unit or right unit) is updated. For packages that remain on the upper layer and have not fallen, their location information remains unchanged.

[0050] Step S6: Repeat delivery The control system repeats steps S3 to S5 until all packages corresponding to the current target delivery address have been delivered. For example, if the current target delivery address corresponds to 3 packages, the robot will deliver the 3 packages in sequence. After each package is delivered, the upper layer of goods will be replenished to the lower layer through a replenishment process to ensure that there are always goods available for delivery at the lower layer.

[0051] Step S7: Continue to the next target address After all packages corresponding to the current target delivery address have been delivered, the control system, based on the delivery task list, controls the delivery robot to move to the next target delivery address and repeats steps S2 to S6 until all packages in the delivery task list have been delivered. After all deliveries are completed, the robot automatically returns to the designated location (such as a charging station or delivery station) to wait for the next task.

[0052] Although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art can still modify the technical solutions described in the foregoing embodiments or make equivalent substitutions for some of the technical features. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the protection scope of the present invention.

Claims

1. A delivery robot with gravity-assisted restocking function, characterized in that, include: The main shell has multiple layers of warehouses arranged vertically inside, and each layer of warehouses is divided into multiple independent warehouse units horizontally. The pushing device, located in the lowest level warehouse, is configured to move bidirectionally in the horizontal direction to push out goods located in the lowest level warehouse unit from either side of the warehouse door. Multiple warehouse switch devices are installed in each warehouse unit except the bottom layer, and are used to open the bottom wall of the corresponding warehouse unit; The cargo detection device is installed in the lowest-level warehouse unit to detect whether there are any goods in the warehouse unit. The chassis running system is used to drive the main body shell to move and steer; A perception and navigation system, mounted on the main body shell, is used for environmental perception and path planning; The control system is electrically connected to the pushing device, the warehouse switching device, the cargo detection device, the chassis walking system, and the sensing and navigation system. The control system is configured such that when the cargo detection device detects that the bottommost cargo unit is empty, the bottom walls of each cargo unit are opened layer by layer from the upper layer adjacent to the bottommost layer, so that the cargo in the upper layer falls to the bottommost layer. The opened bottom walls remain open until there is cargo in the bottommost cargo unit or all the upper cargo units are emptied.

2. The express delivery robot with gravity-assisted layer-drop replenishment function according to claim 1, characterized in that: It also includes a cargo identification device, which is installed at the warehouse door or on the cargo pushing device and is electrically connected to the control system, for reading the identification information of the cargo when the cargo is pushed out.

3. The express delivery robot with gravity-assisted layer-drop replenishment function according to claim 1, characterized in that: The multiple warehouse units are divided into bottom warehouse units and upper warehouse units. The bottom wall of the upper warehouse unit has an openable structure. The pushing device includes a drive motor located below the bottom warehouse unit. The output end of the drive motor is provided with a bidirectional lead screw or synchronous belt. A push plate is provided on the bidirectional lead screw or synchronous belt. A limiting groove is opened on the bottom wall of the bottom warehouse unit. The push plate can move bidirectionally within the range of the limiting groove, and the two sides of the push plate respectively form the bottom warehouse unit.

4. The express delivery robot with gravity-assisted layer-drop replenishment function according to claim 3, characterized in that: The pushing device also includes a push rod and pulleys. The push rod is connected to the top of the push plate, and the pulleys are respectively provided at both ends of the push rod. The pulleys can abut against the corresponding side of the compartment door.

5. The express delivery robot with gravity-assisted layer-drop replenishment function according to claim 3, characterized in that: The cargo compartment switching device is configured as an electromagnetic locking device, and the bottom wall of the upper cargo compartment is connected to the main body shell through the electromagnetic locking device.

6. The express delivery robot with gravity-assisted layer-drop replenishment function according to claim 1, characterized in that: The perception navigation system includes at least one lidar and at least one camera.

7. A control method for a courier delivery robot according to any one of claims 1-6, characterized in that, Includes the following steps: Step S1: Generate a unique code for each express delivery to be delivered and establish a delivery task list. In the delivery task list, the unique code of each express delivery is associated with and stored with the following information: target delivery address, warehouse floor number, and warehouse unit number. Step S2: According to the delivery task list, control the express delivery robot to move to the current target delivery address, and use the cargo detection device to detect whether there are goods in the bottom warehouse unit; Step S3: If there are goods in the bottom warehouse unit, determine whether there is a target express delivery in the delivery task list whose warehouse layer number is the bottom layer and whose target delivery address is the current target delivery address. If it exists, the pusher device is controlled to push the target package out of the corresponding side door; during the pushing process, the unique code of the package is read by the cargo identification device, and the target delivery address of the package is checked to see if it is the current target delivery address. If it is, the delivery is completed; otherwise, the delivery is stopped and an alarm signal is issued. Step S4: After delivery is completed in step S3, the cargo detection device checks again whether the bottom warehouse unit is empty, or if the bottom warehouse unit is detected to be empty in step S2, the layer-by-layer replenishment process is triggered: with the bottom as the first layer, the bottom walls of each warehouse unit are opened layer by layer from the second layer upwards, allowing the goods to fall to the lower layer; the already opened bottom walls remain open, and after each layer is opened, the bottom is checked to see if it is empty. If it is still empty, the next layer is opened until there are goods at the bottom or all the upper layers are cleared. Step S5: Update the warehouse floor number of the dropped package in the delivery task list to the bottom floor, and update its warehouse unit number. Step S6: Repeat steps S3 to S5 until all express deliveries corresponding to the current target delivery address have been delivered. Step S7: According to the delivery task list, control the express delivery robot to move to the next target delivery address, and repeat steps S2 to S6 until all express deliveries in the delivery task list have been delivered.

8. The control method according to claim 7, characterized in that: The multiple warehouse units are divided into three layers vertically, namely the first layer, the second layer, and the third layer, wherein the first layer is the bottom layer warehouse unit; the layer-by-layer replenishment process in step S4 is as follows: First, control the bottom wall of the second-level warehouse unit to open, so that the goods on the second level fall to the first level under the action of gravity. After the bottom wall of the second level is opened, keep it open. Subsequently, the cargo detection device checks whether the first layer is empty. If it is still empty, the bottom wall of the third layer warehouse unit is opened, allowing the cargo on the third layer to fall directly to the first layer warehouse unit under the action of gravity, passing through the already opened second layer warehouse unit. The bottom wall of the third layer remains open after it is opened.

9. The control method according to claim 7, characterized in that: In step S4, the step of detecting whether the bottommost warehouse unit is in an empty state includes: The detection value is obtained by a pressure sensor or photoelectric sensor set at the bottom of the lowest storage unit. If the detection value is lower than a preset threshold, the lowest storage unit is determined to be in an empty state.

10. The control method according to claim 7, characterized in that: In step S2, the step of controlling the express delivery robot to move to the current target delivery address includes: Spatial modeling is performed using LiDAR, environmental perception is achieved using cameras, and the system autonomously plans its path and controls the movement of the chassis walking system. When the delivery robot moves to the elevator entrance of the target building, it also includes an elevator interaction step: the robot recognizes and presses the elevator button by the robotic arm set on the side of the main body shell, and controls the delivery robot to enter the elevator and reach the target floor.

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