Local Map Construction Method and Device for Disconnected Link Scenarios

Abstract

The present invention discloses a method and device for constructing a local map for a broken-link scenario. The method includes: acquiring point cloud data and performing preprocessing, performing inter-frame matching on the preprocessed point cloud data by using a feature point-based inter-frame matching method, and extracting key frames; updating or constructing a local map according to the extracted key frames. The present invention can autonomously construct and provide a local map for a robot.

Description

Technical Field

[0001] The present invention relates to the field of computer technology, and in particular, to a method and device for constructing a local map for a broken link scenario. Background Art

[0002] Simultaneous Localization and Mapping (SLAM) methods are used to solve the problems of positioning and mapping of mobile robots in unknown environments, and can construct two-dimensional or three-dimensional maps of unknown environments. The sensors relied on by this method mainly include lidar and cameras, which are the current mainstream research directions, namely laser SLAM and visual SLAM. In practical applications, the laser SLAM algorithm and engineering applications have tended to be mature, while the visual SLAM algorithm and its engineering applications are still subject to certain limitations.

[0003] In two-dimensional map construction, there are mainly gmapping and cartographer algorithms. Gmapping has a small amount of calculation and high speed, but due to the lack of loop detection, it is only suitable for mapping small areas; the Cartographer algorithm can construct a two-dimensional occupancy grid map through a multi-line lidar or a single-line lidar, with loop detection and map optimization, so the calculation amount is large and the speed is slow, but the mapping effect is good. Three-dimensional map construction is mainly point cloud maps, and classical algorithms include LOAM and a series of improved algorithms for the LOAM algorithm, such as A-LOAM, LeGO-LOAM, etc.

[0004] In addition, the mapping effect is related to the sensor device. The single-line lidar obtains less information, so it is suitable for establishing a two-dimensional grid map in indoor scenes; the multi-line lidar can be used both indoors and outdoors, and its environmental adaptability is stronger than that of the single-line lidar. The quality of mapping also depends on the pose of the sensor. In the absence of a gyroscope sensor, it is generally selected to perform mapping tasks in structured scenes.

[0005] When exploring an unknown environment, it is often restricted by various limitations of the environment. For example, when personnel cannot follow the robot, it is necessary to use remote control to control the robot to collect environmental data. When the environment is relatively complex, or the communication signal is interfered, the communication between the remote control end and the robot is very likely to be broken, and due to environmental restrictions, it is impossible to perform manual recovery. Currently, the mainstream map construction algorithms are all global map construction, which has high requirements for the computing power of the intelligent computing unit. Summary of the Invention

[0006] The purpose of the present invention is to provide a method and device for constructing a local map for a broken link scenario, aiming to solve the above problems in the prior art.

[0007] The present invention provides a method for constructing a local map for a broken link scenario, including:

[0008] Obtain point cloud data and perform preprocessing. For the preprocessed point cloud data, use an inter-frame matching method based on feature points for inter-frame matching and extract key frames.

[0009] Update or construct a local map according to the extracted key frames.

[0010] The present invention provides a local map construction device for a broken link scenario, including:

[0011] An extraction module for obtaining point cloud data and performing preprocessing, using an inter-frame matching method based on feature points for inter-frame matching of the preprocessed point cloud data, and extracting key frames.

[0012] A construction module for updating or constructing a local map according to the extracted key frames.

[0013] An embodiment of the present invention further provides a local map construction device for a broken link scenario, including: a memory, a processor, and a computer program stored on the memory and executable on the processor. When the computer program is executed by the processor, the steps of the above-mentioned local map construction method for a broken link scenario are implemented.

[0014] An embodiment of the present invention further provides a computer-readable storage medium, on which an implementation program for information transmission is stored. When the program is executed by a processor, the steps of the above-mentioned local map construction method for a broken link scenario are implemented.

[0015] Adopting the embodiment of the present invention, when a communication interruption occurs between a robot exploration scenario and a remote control end during scene data acquisition, it can autonomously construct and provide a local map for the robot, and then make it retreat to a position where communication can be established. It is a lightweight map construction method. The robot can return to the link establishment point based on the established local map.

[0016] The above description is only an overview of the technical solution of the present invention. In order to be able to understand the technical means of the present invention more clearly, it can be implemented according to the content of the description. And in order to make the above and other purposes, features, and advantages of the present invention more obvious and understandable, the following specifically describes the embodiments of the present invention. Description of the Drawings

[0017] In order to more clearly illustrate the specific embodiments of the present invention or the technical solutions in the prior art, the following will briefly introduce the drawings required for the description of the specific embodiments or the prior art. Obviously, the following drawings are some embodiments of the present invention. For those of ordinary skill in the art, other drawings can be obtained based on these drawings without creative efforts.

[0018] Figure 1 It is a flowchart of the local map construction method for the broken link scenario in an embodiment of the present invention;

[0019] Figure 2 It is a flowchart of the detailed processing of the local map construction method for the broken link scenario in an embodiment of the present invention;

[0020] Figure 3 It is a schematic diagram of the local map construction device for the broken link scenario in the first embodiment of the device of the present invention;

[0021] Figure 4 It is a schematic diagram of the local map construction device for the broken link scenario in the second embodiment of the device of the present invention. Detailed implementation manners

[0022] To solve the problem of robot recovery in the prior art and reduce the computing power requirement for the intelligent computing unit, the embodiments of the present invention provide a local map construction method and device for the broken link scenario. Specifically, when the robot explores the scenario and obtains scenario data, and a communication interruption occurs with the remote control terminal, it can autonomously construct and provide a local map for the robot, and then make it retreat to a position where communication can be established. It is a lightweight map construction method and device. Applying the Simultaneous Localization and Mapping (SLAM) method to the robot exploration scenario can better complete the exploration task.

[0023] Next, the technical solutions of the present invention will be described clearly and completely in conjunction with the embodiments. Obviously, the described embodiments are some embodiments of the present invention, rather than all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without creative efforts shall fall within the protection scope of the present invention.

[0024] In the description of the present invention, it should be understood that the orientation or positional relationship indicated by the terms "center", "longitudinal", "transverse", "length", "width", "thickness", "upper", "lower", "front", "rear", "left", "right", "vertical", "horizontal", "top", "bottom", "inner", "outer", "clockwise", "counterclockwise", etc. is based on the orientation or positional relationship shown in the drawings, and is only for the convenience of describing the present invention and simplifying the description, rather than indicating or implying that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore should not be construed as a limitation to the present invention.

[0025] In addition, the terms "first" and "second" are for descriptive purposes only and should not be construed as indicating or implying relative importance or implicitly specifying the quantity of the indicated technical features. Thus, features defined with "first" and "second" may explicitly or implicitly include one or more of the said features. In the description of the present invention, "a plurality of" means two or more unless otherwise specifically defined. In addition, the terms "mounted", "connected", and "coupled" should be construed broadly. For example, it may be a fixed connection, a detachable connection, or an integral connection; it may be a mechanical connection or an electrical connection; it may be directly connected or indirectly connected through an intermediate medium, and it may be the communication inside two elements. For those of ordinary skill in the art, the specific meanings of the above terms in the present invention can be understood according to specific circumstances.

[0026] Method Embodiment

[0027] According to an embodiment of the present invention, a method for constructing a local map for a broken link scenario is provided. Figure 1 is a flowchart of the method for constructing a local map for a broken link scenario according to an embodiment of the present invention, as Figure 1 shown, the method for constructing a local map for a broken link scenario according to an embodiment of the present invention specifically includes:

[0028] Step 101: Obtain point cloud data and perform preprocessing, and perform inter-frame matching on the preprocessed point cloud data using a feature point-based inter-frame matching method to extract key frames.

[0029] Step 101 specifically includes:

[0030] Extract features from the preprocessed point cloud data, extract the features of corner points, edge points, and plane points to form corresponding feature point sequences and their descriptors with rotational invariance, translational invariance, and scale invariance, and form a global descriptor according to statistics;

[0031] Extract key frames according to the global descriptor, and after extracting the key frames, match all feature points with the previous key frame and calculate the pose transformation matrix. Among them, the extraction of key frames specifically includes:

[0032] Select key frames at a certain interval by judging whether the number of frames exceeds a threshold; or,

[0033] Select key frames according to a certain movement distance by calculating the inter-frame pose transformation matrix; or,

[0034] Select key frames according to the number of co-visible feature points by comparing the number of associated features.

[0035] Step 102: Update or construct a local map according to the extracted key frames.

[0036] Step 102 specifically includes: inserting key frames into the local map, storing the current trajectory points in the trajectory sequence, and determining the number of key frames in the current local map. If it exceeds a predetermined threshold, the earliest key frame and the corresponding trajectory points are deleted, where the local map contains a fixed number of key frames.

[0037] After step 102, the following processing can also be performed:

[0038] When the remote control terminal is disconnected from the robot, the local map and the real-time point cloud data are used as the navigation map, the trajectory point sequence is reversed to become the target point sequence, and the robot retreats to a position where communication can be established according to the updated or constructed local map.

[0039] The above technical solutions of the embodiments of the present invention will be described in detail below with reference to the accompanying drawings.

[0040] Figure 2 is a detailed processing flowchart of the method of the embodiment of the present invention. As Figure 2 shown, the embodiment of the present invention provides a method for constructing a local map for a disconnection scenario. Specifically, when the robot explores the scenario and obtains scenario data, a communication interruption occurs with the remote control terminal. It can autonomously construct and provide a local map for the robot, and then make it retreat to a position where communication can be established. It is a lightweight map construction method, aiming to solve the problem of robot recovery in the disconnection scenario. Specifically, it includes:

[0041] 1. Feature point-based inter-frame matching method:

[0042] Feature extraction is performed on the preprocessed point cloud data to extract features such as corner points, edge points, and plane points, forming a corresponding feature point sequence and its descriptor, and a global descriptor is formed according to statistics. The global descriptor is used to extract key frames. After extracting the key frames, all feature points are matched with the previous key frame to calculate the pose transformation matrix. That is to say, in the embodiment of the present invention, the environmental perception data is mainly classified into corner points, edge points, and plane points, and descriptors with rotation invariance, translation invariance, and scale invariance are established for feature points such as corner points. In addition, a multi-line lidar can be used to extract the scene at the above key feature points, obtain its coordinates in the radar coordinate system, and calculate its feature descriptor for matching between key frames and calculating the pose transformation matrix.

[0043] 2. Key frame extraction:

[0044] The key frame is currently a relatively common method, which can represent the frames near it, reduce the number of frames to be optimized, and thus reduce the calculation amount.

[0045] The selected indicators mainly include:

[0046] (1) Select key frames at regular intervals, which can be achieved by judging whether the number of frames exceeds a threshold. The advantage is that it is easy to program, but the effect is poor. When the movement is slow, a large number of similar key frames will be selected, resulting in data redundancy. When the movement is fast, many important frames will be lost;

[0047] (2) Select key frames according to a certain movement distance, which can be achieved by calculating the pose transformation matrix between frames. When the movement is sufficient, new key frames will be generated. The advantage is that it has a good tolerance for speed, and the disadvantage is that a large number of similar key frames will be generated when making reciprocating movements in an area;

[0048] (3) Select key frames according to the number of co-visible feature points, which can be achieved by comparing the number of associated features. When the number of associated features between two frame point clouds drops to a certain threshold, it is considered about to leave the current scene and move to the next scene. The advantage is that the effect is good, and the disadvantage is that the implementation is relatively complex;

[0049] 3. Update of the local map:

[0050] The local map contains a fixed number of key frames. When the total number of key frames in the map is greater than the threshold, the earliest key frame in the map is eliminated. Compared with the global map, the advantage is that it can ignore the drift error to a certain extent, with less computational complexity and less storage space required. The disadvantage is that there is no global map, so it is only for a specific scenario of remote control disconnection. In actual implementation, key frames can be inserted into the local map, the current trajectory points can be stored in the trajectory sequence, and the number of key frames in the current local map can be judged. If it exceeds the threshold, the earliest key frame and the corresponding trajectory points are deleted. When there is a disconnection between the remote control end and the robot, the local map and the real-time point cloud data will be used as the navigation map, and the trajectory point sequence will be reversed to become the target point sequence until the link is re-established and the task ends.

[0051] In summary, the embodiment of the present invention provides a method for constructing a local map for a disconnection scenario. Specifically, when the robot explores the scenario and obtains scenario data and has a communication interruption with the remote control end, it can autonomously construct and provide a local map for the robot, and then make it retreat to a position where communication can be established. It is a lightweight map construction method. In the experiment, the robot can return to the link establishment point based on the established local map.

[0052] Device Embodiment 1

[0053] According to the embodiment of the present invention, a device for constructing a local map for a disconnection scenario is provided. Figure 3 It is a schematic diagram of the device for constructing a local map for a disconnection scenario of the first device embodiment of the present invention, as Figure 3As shown in the figure, the local map construction device for broken chain scenarios according to an embodiment of the present invention specifically includes:

[0054] An extraction module 30, configured to obtain point cloud data and perform preprocessing, perform inter-frame matching on the preprocessed point cloud data using an inter-frame matching method based on feature points, and perform key frame extraction; specifically, the extraction module 30 is configured to:

[0055] Perform feature extraction on the preprocessed point cloud data, extract the features of corner points, edge points, and plane points, form corresponding feature point sequences and their descriptors with rotational invariance, translational invariance, and scale invariance, and form a global descriptor according to statistics; extract key frames according to the global descriptor, and after extracting the key frames, match all feature points with the previous key frame and calculate the pose transformation matrix, wherein, by judging whether the number of frames exceeds a threshold, select key frames at a certain interval; or, by calculating the inter-frame pose transformation matrix, select key frames according to a certain movement distance; or, by comparing the number of associated features, select key frames according to the number of co-visible feature points;

[0056] A construction module 32, configured to update or construct a local map according to the extracted key frames.

[0057] Specifically, the construction module 32 is configured to:

[0058] Insert the key frame into the local map, store the current trajectory point into the trajectory sequence, and judge the number of key frames in the current local map. If it exceeds a predetermined threshold, delete the earliest key frame and the corresponding trajectory point, wherein the local map contains a fixed number of key frames.

[0059] The above device may further include:

[0060] A withdrawal module, configured to use the local map and real-time point cloud data as a navigation map when a broken chain occurs between the remote control terminal and the robot, reverse the trajectory point sequence into a target point sequence, and withdraw to a position where communication can be established according to the updated or constructed local map.

[0061] The embodiment of the present invention is a device embodiment corresponding to the above method embodiment. The specific operations of each module can be understood with reference to the description of the method embodiment, and will not be elaborated here.

[0062] Device Embodiment Two

[0063] An embodiment of the present invention provides a local map construction device for broken chain scenarios, as Figure 4As shown, it includes: a memory 40, a processor 42, and a computer program stored on the memory 40 and executable on the processor 42. When the computer program is executed by the processor 42, it implements the steps described in the method embodiments.

[0064] Device Embodiment III

[0065] An embodiment of the present invention provides a computer-readable storage medium. An implementation program for information transmission is stored on the computer-readable storage medium. When the program is executed by the processor 42, it implements the steps described in the method embodiments.

[0066] The computer-readable storage medium described in this embodiment includes, but is not limited to: ROM, RAM, magnetic disk, optical disc, etc.

[0067] The specific embodiments of this specification have been described above. Other embodiments are within the scope of the appended claims. In some cases, the actions or steps recited in the claims can be executed in a different order than in the embodiments and still achieve the desired result. Additionally, the processes depicted in the drawings do not necessarily require the particular order or sequential order shown to achieve the desired result. In certain embodiments, multitasking and parallel processing are also possible or may be advantageous.

[0068] In the 1930s, improvements to a technology could be clearly distinguished as either hardware improvements (e.g., improvements to circuit structures such as diodes, transistors, switches, etc.) or software improvements (improvements to method flows). However, with the development of technology, many method flow improvements today can be regarded as direct improvements to hardware circuit structures. Designers almost always obtain the corresponding hardware circuit structure by programming the improved method flow into the hardware circuit. Therefore, it cannot be said that an improvement to a method flow cannot be implemented using a hardware entity module. For example, a Programmable Logic Device (PLD) (such as a Field Programmable Gate Array (FPGA)) is an integrated circuit whose logic function is determined by the user programming the device. Designers can program themselves to "integrate" a digital system onto a single PLD, without having to ask a chip manufacturer to design and fabricate a dedicated integrated circuit chip. Moreover, nowadays, instead of manually fabricating integrated circuit chips, this programming is mostly implemented using "logic compiler" software, which is similar to the software compiler used in program development and writing. The original code before compilation also has to be written in a specific programming language, which is called a Hardware Description Language (HDL), and there is not just one kind of HDL, but many kinds, such as ABEL (Advanced Boolean Expression Language), AHDL (Altera Hardware Description Language), Confluence, CUPL (Cornell University Programming Language), HDCal, JHDL (Java Hardware Description Language), Lava, Lola, MyHDL, PALASM, RHDL (Ruby Hardware Description Language), etc. The most commonly used ones currently are VHDL (Very-High-Speed Integrated Circuit Hardware Description Language) and Verilog. Those skilled in the art should also be aware that by simply performing a little logical programming on the method flow using the above-mentioned several hardware description languages and programming it into an integrated circuit, it is easy to obtain the hardware circuit that implements the logical method flow.

[0069] The controller can be implemented in any suitable manner. For example, the controller can take the form of, for example, a microprocessor or a processor and a computer-readable medium storing computer-readable program code (such as software or firmware) executable by the (micro)processor, logic gates, switches, an application specific integrated circuit (ASIC), a programmable logic controller, and an embedded microcontroller. Examples of the controller include, but are not limited to, the following microcontrollers: ARC 625D, Atmel AT91SAM, Microchip PIC18F26K20, and Silicone Labs C8051F320. The memory controller can also be implemented as part of the control logic of the memory. Those skilled in the art also know that in addition to implementing the controller in the form of pure computer-readable program code, it is entirely possible to make the controller implement the same function in the form of logic gates, switches, application specific integrated circuits, programmable logic controllers, and embedded microcontrollers by logically programming the method steps. Therefore, such a controller can be considered a hardware component, and the devices included therein for implementing various functions can also be regarded as the structures within the hardware component. Or even, the devices for implementing various functions can be regarded as either software modules for implementing the method or the structures within the hardware component.

[0070] The systems, devices, modules, or units illustrated in the above embodiments can be specifically implemented by computer chips or entities, or by products with certain functions. A typical implementation device is a computer. Specifically, the computer can be, for example, a personal computer, a laptop computer, a cellular phone, a camera phone, a smart phone, a personal digital assistant, a media player, a navigation device, an email device, a game console, a tablet computer, a wearable device, or any combination of these devices.

[0071] For the convenience of description, when describing the above devices, they are described separately as various units according to their functions. Of course, when implementing the embodiments of this specification, the functions of each unit can be implemented in the same or multiple software and / or hardware.

[0072] Those skilled in the art should understand that one or more embodiments of this specification can be provided as a method, a system, or a computer program product. Therefore, one or more embodiments of this specification can take the form of a complete hardware embodiment, a complete software embodiment, or an embodiment combining software and hardware aspects. Moreover, this specification can take the form of a computer program product implemented on one or more computer-usable storage media (including but not limited to disk memory, CD-ROM, optical memory, etc.) containing computer-usable program code.

[0073] This specification is described with reference to the flowcharts and / or block diagrams of methods, apparatus (systems), and computer program products according to embodiments of the specification. It should be understood that each flow and / or block in the flowchart and / or block diagram, and combinations of flows and / or blocks in the flowchart and / or block diagram, can be implemented by computer program instructions. These computer program instructions can be provided to the processors of a general-purpose computer, special-purpose computer, embedded processor, or other programmable data processing device to generate a machine, such that the instructions executed by the processors of the computer or other programmable data processing device produce means for implementing the functions specified in one or more of the flows Figure 1 one or more of the flows and / or blocks Figure 1 or means for implementing the functions specified in one or more of the blocks.

[0074] These computer program instructions can also be stored in a computer-readable memory that can direct a computer or other programmable data processing device to operate in a particular manner, such that the instructions stored in the computer-readable memory produce a manufacture including instruction means for implementing the functions specified in one or more of the flows Figure 1 one or more of the flows and / or blocks Figure 1 or means for implementing the functions specified in one or more of the blocks.

[0075] These computer program instructions can also be loaded onto a computer or other programmable data processing device, such that a series of operational steps are performed on the computer or other programmable device to generate a computer-implemented process, and thus the instructions executed on the computer or other programmable device provide steps for implementing the functions specified in one or more of the flows Figure 1 one or more of the flows and / or blocks Figure 1 or means for implementing the functions specified in one or more of the blocks.

[0076] In a typical configuration, a computing device includes one or more processors (CPUs), an input / output interface, a network interface, and memory.

[0077] The memory may include non-permanent memory in the form of computer-readable media, random access memory (RAM), and / or non-volatile memory, such as read-only memory (ROM) or flash memory. The memory is an example of computer-readable media.

[0078] Computer readable media include permanent and non-permanent, removable and non-removable media that can be implemented by any method or technology to store information. Information can be computer readable instructions, data structures, program modules or other data. Examples of computer storage media include, but are not limited to, phase change memory (PRAM), static random access memory (SRAM), dynamic random access memory (DRAM), other types of random access memory (RAM), read-only memory (ROM), electrically erasable programmable read-only memory (EEPROM), flash memory or other memory technology, compact disk read-only memory (CD-ROM), digital versatile disk (DVD) or other optical storage, magnetic cassettes, magnetic tape magnetic disk storage or other magnetic storage devices or any other non-transmission media that can be used to store information that can be accessed by a computing device. As defined herein, computer readable media does not include temporary computer readable media (transitory media), such as modulated data signals and carrier waves.

[0079] It should also be noted that the terms "include", "comprises" or any other variations thereof are intended to cover non-exclusive inclusion, so that a process, method, commodity or device including a series of elements includes not only those elements, but also other elements not explicitly listed, or also includes elements inherent to such process, method, commodity or device. In the absence of more restrictions, the elements defined by the sentence "comprises a ..." do not exclude the existence of other identical elements in the process, method, commodity or device including the elements.

[0080] One or more embodiments of the present specification may be described in the general context of computer-executable instructions executed by a computer, such as program modules. Generally, program modules include routines, programs, objects, components, data structures, etc. that perform specific tasks or implement specific abstract data types. One or more embodiments of the present specification may also be practiced in distributed computing environments where tasks are performed by remote processing devices connected through a communication network. In a distributed computing environment, program modules may be located in local and remote computer storage media, including storage devices.

[0081] Each embodiment in this specification is described in a progressive manner, and the same or similar parts between the embodiments can be referred to each other, and each embodiment focuses on the differences from other embodiments. In particular, for the system embodiment, since it is basically similar to the method embodiment, the description is relatively simple, and the relevant parts can be referred to the partial description of the method embodiment.

[0082] The above are only examples of this document and are not intended to limit this document. For those skilled in the art, this document may have various changes and modifications. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of this document shall be included within the scope of the claims of this document.

Claims

1. A local map construction method for the broken link scenario, characterized in that, Including: Obtain point cloud data and perform preprocessing. For the preprocessed point cloud data, use an inter-frame matching method based on feature points for inter-frame matching and extract key frames. Specifically including: Extract features from the preprocessed point cloud data, extract the features of corner points, edge points and plane points, form corresponding feature point sequences and their descriptors with rotational invariance, translational invariance and scale invariance, and form a global descriptor according to statistics; Extract key frames according to the global descriptor, and after extracting key frames, match all feature points with the previous key frame and calculate the pose transformation matrix. Update or construct a local map according to the extracted key frames. When the remote control end is disconnected from the robot, use the local map and real-time point cloud data as the navigation map, reverse the trajectory point sequence to become the target point sequence, and withdraw to a position where communication can be established according to the updated or constructed local map.

2. The method according to claim 1, characterized in that, The specific process of extracting key frames includes: Select key frames at a certain interval by judging whether the number of frames exceeds a threshold; or Select key frames according to a certain movement distance by calculating the inter-frame pose transformation matrix; or Select key frames according to the number of co-visible feature points by comparing the associated feature quantities.

3. The method according to claim 1, characterized in that The specific process of updating or constructing a local map according to the extracted key frames includes: Insert the key frame into the local map, store the current trajectory point in the trajectory sequence, and judge the number of key frames in the current local map. If it exceeds the predetermined threshold, delete the earliest key frame and the corresponding trajectory point, where the local map contains a fixed number of key frames.

4. A local map construction device for a broken link scenario, characterized in that, Including: An extraction module for obtaining point cloud data and performing preprocessing, using an inter-frame matching method based on feature points for inter-frame matching of the preprocessed point cloud data and extracting key frames; The extraction module is specifically used for: Extract features from the preprocessed point cloud data, extract the features of corner points, edge points and plane points, form corresponding feature point sequences and their descriptors with rotational invariance, translational invariance and scale invariance, and form a global descriptor according to statistics; Extract key frames according to the global descriptor, and after extracting key frames, match all feature points with the previous key frame and calculate the pose transformation matrix. A construction module for updating or constructing a local map according to the extracted key frames. A withdrawal module for, when the remote control end is disconnected from the robot, using the local map and real-time point cloud data as the navigation map, reversing the trajectory point sequence to become the target point sequence, and withdrawing to a position where communication can be established according to the updated or constructed local map.

5. The device according to claim 4, wherein The extraction module is specifically used for: Select key frames at a certain interval by judging whether the number of frames exceeds a threshold; or select key frames according to a certain movement distance by calculating the inter-frame pose transformation matrix; or select key frames according to the number of co-visible feature points by comparing the associated feature quantities; The construction module is specifically used for: Insert the key frame into the local map, store the current trajectory point in the trajectory sequence, and determine the number of key frames in the current local map. If it exceeds the predetermined threshold, delete the earliest key frame and the corresponding trajectory point, where the local map contains a fixed number of key frames.

6. A local map construction device for a broken link scenario, characterized in that, It includes: A memory, a processor, and a computer program stored on the memory and executable on the processor. When the computer program is executed by the processor, it implements the steps of the method for constructing a local map for a broken link scenario according to any one of claims 1 to 3.

7. A computer-readable storage medium, characterized in that, An implementation program for information transmission is stored on the computer-readable storage medium. When the program is executed by the processor, it implements the steps of the method for constructing a local map for a broken link scenario according to any one of claims 1 to 3.

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