A method and device based on Lora target tracking

Abstract

The purpose of this application is to provide a method and device based on Lora target tracking. This application expands the internal radio frequency channel of Lora, constructs a circular array antenna structure, and obtains a modified Lora; the modified Lora is installed on the robot body, receives the signal sent by the tracked object, and measures the arrival time difference positioning through multiple channels to obtain the target angle and relative distance; the tracked object is tracked according to the target angle and relative distance. In this way, the mobile robot can realize the function of tracking a specified target and realize the function of multi-scenario target tracking. It can not only achieve the robustness of tracking and protect the privacy of users, but also reduce costs to meet usage requirements.

Description

Technical Field

[0001] The present application relates to the field of robotics, and in particular to a method and device based on Lora target tracking. Background Art

[0002] In service robot applications, guidance and tracking services play an important role in production and life. For example, in applications such as personnel tracking, monitoring, and contactless delivery, corresponding services can be provided based on the location information of the target and the robot. However, for the tracking and positioning of dynamic targets and unknown targets, there are still problems with the system coverage distance and accuracy.

[0003] In target tracking, methods based on image features and visual servoing have shown good application results in drones and other devices. However, for multiple targets, this solution often cannot guarantee the stability of the system. At the same time, in robot applications, it faces the problem of target user privacy. In the research on wireless positioning of target nodes, many research institutions and scholars at home and abroad have achieved remarkable performance results in research based on "fingerprint database" and signal arrival angle. However, in complex indoor and outdoor environments, there is still no effective solution for multi-scenario compatible positioning technology and system.

[0004] Using the Lora network module, the Lora network integrates the capabilities of long-distance communication and signal flight time measurement, providing strong support for long-distance indoor positioning and communication services. However, in indoor scenarios, due to the lack of GPS reference signals, inertial units are prone to significant errors in long-term integration operations, making it difficult to obtain the user's position and movement trajectory. At this time, when only signal flight time is used for positioning, multiple base stations need to be deployed, which increases the cost and deployment difficulty of the system, and is not convenient for scenario expansion. Summary of the invention

[0005] One purpose of the present application is to provide a method and device based on Lora target tracking to solve the problems in the prior art of difficulty in ensuring system stability, high cost, infringement of target user privacy, and incompatibility with multi-scenario target tracking functions.

[0006] According to one aspect of the present application, a method for tracking a target based on Lora is provided, the method comprising:

[0007] Expand the internal RF channel of Lora, build a circular array antenna structure, and obtain the modified Lora;

[0008] The modified Lora is installed on the robot body, the signal sent by the tracked object is received, and the arrival time difference positioning is measured through multiple channels to obtain the target angle and relative distance;

[0009] The tracked object is tracked according to the target angle and the relative distance.

[0010] Optionally, expand the internal RF channel of Lora to build a circular array antenna structure, including:

[0011] The base station RF channels are reused through the internal RF switch of Lora to expand the number of external antennas;

[0012] A circular array antenna structure is constructed based on an extended external antenna.

[0013] Optionally, the measurement of arrival time difference positioning through multiple channels includes:

[0014] The data of the tracked object is collected through multiple channels determined by the constructed circular array antenna structure, and the arrival time difference positioning is measured based on the collected data.

[0015] Optionally, performing a time difference of arrival positioning measurement based on the collected data includes:

[0016] In the arrival time difference positioning algorithm, the array direction when the circular array antenna structure is rotated is recorded, and the arrival angle is obtained, and the arrival angle is used as the target angle;

[0017] The relative distance is obtained according to the array direction and the angle of arrival.

[0018] Optionally, in the arrival time difference positioning algorithm, the array direction when the circular array antenna structure is rotated is recorded, and the arrival angle is obtained, including:

[0019] In the arrival time difference positioning algorithm, the first flight time of the first antenna collected and the array direction are recorded;

[0020] When the nth antenna in the circular array antenna structure is measured at the nth flight time, the target angle to which the array is rotated is obtained, where n=2, 3, ...

[0021] Optionally, the method comprises:

[0022] The distance difference between the first antenna and the nth antenna from the first flight time to the nth flight time is calculated according to the array direction and the target angle.

[0023] Optionally, after obtaining the target angle to which the array is rotated, the following steps are performed:

[0024] A step factor is selected, and the target angle is iteratively updated according to the step factor, the acquired array direction, the initialized angle, and the offset.

[0025] Optionally, tracking the tracked object according to the target angle and the relative distance includes:

[0026] By rotating the array antenna structure, the target angle and relative distance between each antenna in the annular array antenna structure and the first antenna are obtained, and the tracked object is tracked according to the target angle and relative distance of each group.

[0027] According to another aspect of the present application, a device based on Lora target tracking is also provided, the device comprising:

[0028] one or more processors; and

[0029] A memory storing computer readable instructions, which, when executed, cause the processor to perform the operations of the method as described above.

[0030] According to another aspect of the present application, a computer-readable medium is provided, on which computer-readable instructions are stored. The computer-readable instructions can be executed by a processor to implement the method described above.

[0031] Compared with the prior art, this application expands the internal radio frequency channel of Lora and constructs a circular array antenna structure to obtain a modified Lora; the modified Lora is installed on the robot body, receives the signal sent by the tracked object, measures the arrival time difference positioning through multiple channels, and obtains the target angle and relative distance; the tracked object is tracked according to the target angle and relative distance. In this way, the mobile robot can realize the function of tracking a specified target and realize the function of multi-scenario target tracking, which can not only achieve the robustness of tracking and protect the privacy of users, but also reduce costs to meet usage requirements. BRIEF DESCRIPTION OF THE DRAWINGS

[0032] Other features, objects and advantages of the present application will become more apparent by reading the detailed description of non-limiting embodiments made with reference to the following drawings:

[0033] Figure 1 A schematic diagram of a Lora-based target tracking method according to one aspect of the present application is shown;

[0034] Figure 2 A schematic diagram showing a ring array antenna structure in an embodiment of the present application is shown;

[0035] Figure 3 A schematic diagram showing target tracking based on a ring array antenna structure in one embodiment of the present application is shown;

[0036] Figure 4 A schematic diagram showing signal arrival angle measurement in an embodiment of the present application is shown.

[0037] The same or similar reference numerals in the drawings represent the same or similar components. DETAILED DESCRIPTION

[0038] The present application is described in further detail below in conjunction with the accompanying drawings.

[0039] In a typical configuration of the present application, the terminal, the device of the service network and the trusted party all include one or more processors (eg, a central processing unit (CPU)), an input / output interface, a network interface and a memory.

[0040] Memory may include non-permanent storage in a computer-readable medium, random access memory (RAM) and / or non-volatile memory in the form of read-only memory (ROM) or flash RAM. Memory is an example of a computer-readable medium.

[0041] Computer readable media include permanent and non-permanent, removable and non-removable media that can be used to store information by any method or technology. 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 RAM (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 Disc Read-Only Memory (CD-ROM), Digital Versatile Disk (DVD) or other optical storage, magnetic cassettes, tape 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. According to the definition in this article, computer-readable media does not include non-transitory media such as modulated data signals and carrier waves.

[0042] Figure 1A schematic flow chart of a method for target tracking based on Lora provided according to one aspect of the present application is shown, the method comprising: steps S11 to S13, wherein, in step S11, the internal radio frequency channel of Lora is expanded, a circular array antenna structure is constructed, and a modified Lora is obtained; in step S12, the modified Lora is installed on the robot body, the signal sent by the tracked object is received, and the arrival time difference positioning is measured through multiple channels to obtain the target angle and relative distance; in step S13, the tracked object is tracked according to the target angle and relative distance. Thus, the mobile robot can realize the function of tracking a specified target and realize the function of tracking targets in multiple scenarios, which can not only realize the robustness of tracking and protect the privacy of users, but also reduce costs to meet the use requirements.

[0043] Specifically, in step S11, the internal radio frequency channel of Lora is expanded, and a circular array antenna structure is constructed to obtain a modified Lora. Here, the Lora low-cost Internet of Things module is modified based on hardware, and a circular array antenna structure is constructed to realize the reception of multi-channel signals, and target tracking is performed based on the modified Lora.

[0044] Specifically, in step S12, the modified Lora is installed on the robot body, the signal sent by the tracked object is received, and the arrival time difference positioning is measured through multiple channels to obtain the target angle and relative distance; here, the modified Lora gateway is composed of a modified circular array antenna structure, which is installed on the robot body and placed on the servo. The tracked object can carry an ordinary Lora module, and the signal is sent to be received by the modified Lora gateway on the mobile robot. The signal sent by the tracked object is received through the multiple channels composed of the circular array antenna structure, and the arrival time difference positioning (TDOF) is measured according to the received signal to obtain the target angle and relative distance, the target angle is the angle during the rotation of the circular array antenna, and the relative distance is the relative distance between the tracked object and the antenna.

[0045] Specifically, in step S13, the tracked object is tracked according to the target angle and the relative distance. Here, the robot tracks the tracked object according to the target angle and the relative distance obtained by the rotating loop antenna.

[0046] In one embodiment of the present application, in step S11, the base station RF channel is reused by the RF switch inside Lora to expand the number of external antennas; a ring array antenna structure is constructed based on the expanded external antennas. Here, the base station RF channel is reused by a low-cost RF switch to expand the number of external antennas to achieve the purpose of spectrum spread, so that at each moment, at least three anchor nodes can receive the signal sent by the tracked object to achieve target positioning. Figure 2 As shown, the number of external antennas is expanded to obtain a circular array antenna structure. In the figure, 1, 2, 3, and 4 are four anchor nodes (i.e., 4 antennas) in the circular array antenna structure, and d represents the distance value from the tracked object (target) to the receiving antenna. The modified Lora internal multi-channel antenna simultaneously collects data from the tracked object to achieve target positioning; Figure 2 The target is detected by anchor nodes 1, 2, 3, and 4 at the same time, and the target posture can be obtained through triangulation. In step S12, data of the tracked object is collected through multiple channels determined by the constructed circular array antenna structure, and the arrival time difference positioning is measured based on the collected data. Figure 3 As shown in the figure, the Lora gateway modified on the robot collects data through the internal rotating circular array, and uses the collected data to measure TDoF, thereby calculating the angle of arrival (AOA) and estimating the AOA during the rotation of the array. The modified Lora gateway is composed of a circular array antenna structure and supports simultaneous sampling of signals by multiple RF channels. The gateway can analyze the angle of arrival of the signal by comparing the phase difference of the signal on different channels, thereby estimating the target angle and achieving the purpose of target tracking.

[0047] In one embodiment of the present application, the array direction when the circular array antenna structure is rotated is recorded in the arrival time difference positioning algorithm, and the arrival angle is obtained, and the arrival angle is used as the target angle; the relative distance is obtained according to the array direction and the arrival angle. Here, the TDoF records the array direction corresponding to the rotation of the antenna in the above circular array antenna structure when it arrives at a preset time, such as the array direction of antenna A and the array direction of antenna B, and measures the angle arrived within the preset time to obtain the target angle corresponding to the rotated antenna. The obtained target angle and array direction are then used to calculate the relative distance between the antenna and the tracked object.

[0048] Specifically, the first flight time of the first antenna collected and the array direction are recorded in the arrival time difference positioning algorithm; when the nth antenna in the circular array antenna structure is measured at the nth flight time, the target angle to which the array is rotated is obtained, where n = 2, 3, .... Here, it is assumed that the first flight time (ToF1) from antenna b is measured at time t1 and the array direction is (t1), and when the second flight time (ToF2) is measured from antenna a, the array is rotated to an angle (t2).

[0049] Next, after obtaining the target angle to which the array is rotated, a step factor is selected, and the target angle is iteratively updated according to the step factor, the acquired array direction, the initialized angle, and the offset. Here, after rotating the antenna, the TDoF calculated from ToF1 to ToF2 includes the difference caused by the direction, and the difference caused by the rotation can be calculated as a gradient update parameter of the number. The distance difference between the i-th antenna and the first antenna in the circular array antenna structure can be obtained by the following formula:

[0050] Δd i1 =c×(ToF i -ToF1), i=2, 3, ..., n.

[0051] Among them, c represents the transmission speed of the modified Lora signal, ToF i represents the i-th flight time corresponding to the i-th antenna.

[0052] like Figure 4 As shown, the relationship between the target angle and the antenna array distance difference can be expressed by the following formula:

[0053]

[0054] Where θ(t) is the AOA angle, is the array direction, r is the radius of the array antenna, and in rotation, the direction Recorded in the TDoF experiment. AoAθ and bias are initialized and then further updated in iterations. In each calculation, a step size factor μ is chosen to use the objective function.

[0055] Since the objective function is not a convex function, it is difficult to calculate a solution close to the form. Therefore, the following stochastic gradient descent (SGD) optimization is used to find a solution for AoA estimation:

[0056]

[0057] Among them, b is the bias, which is the deviation caused by the system hardware, and Δd is the observed measurement difference. The optimal position and posture of the target can be obtained by minimizing the error between the two.

[0058] In one embodiment of the present application, the distance difference between the first antenna and the nth antenna from the first flight time to the nth flight time is calculated according to the array direction and the target angle. Figure 4 As shown, the antennas in the array antenna structure are rotated to obtain the array direction and target angle of each antenna, so that the rotation angle between the first flight time of the first antenna and the nth antenna during the nth flight time, that is, the target angle (θ) when reaching the nth antenna, can be obtained. n) and the target angle to obtain the distance difference Δd between the first antenna and the nth antenna.

[0059] In one embodiment of the present application, in step S14, by rotating the array antenna structure, the target angle and relative distance between each antenna in the annular array antenna structure and the first antenna are obtained, and the tracked object is tracked according to the target angle and relative distance of each group. Figure 4 , the array antenna structure is rotated, so that the target angle (θ) between the first antenna and other antennas can be obtained, so that the tracked object can be positioned in all directions, ensuring that it can be monitored by multiple antennas at the same time, realizing distance angle estimation, and thus achieving the purpose of target estimation. It does not require additional scene deployment and user privacy, and it is easy to expand to multiple scenes to achieve target tracking.

[0060] This application can realize the mobile robot's function of tracking a designated target and realize the multi-scenario target tracking function. It can not only realize the robustness of tracking and protect user privacy, but also reduce costs to meet usage needs. Through the method described in this application, based on the hardware modification of the Lora low-cost Internet of Things module, through multi-channel TDoF measurement, and using the AOA algorithm, the estimation of the target angle is achieved. Specifically, the mobile robot carries a modified Lora gateway, which is composed of a modified circular array antenna structure, which is then installed on the robot body and placed on the servo. The tracked object carries an ordinary lightweight Lora module, which is received by the mobile robot Lora gateway by sending a signal to achieve distance angle estimation, thereby achieving the purpose of target estimation.

[0061] In addition, an embodiment of the present application also provides a computer-readable medium on which computer-readable instructions are stored. The computer-readable instructions can be executed by a processor to implement the aforementioned Lora-based target tracking method.

[0062] Corresponding to the method described above, the present application also provides a terminal, which includes a terminal capable of executing the above Figure 1 Or the modules or units of the method steps described in each embodiment, these modules or units can be implemented by hardware, software or a combination of hardware and software, and this application is not limited. For example, in one embodiment of this application, a device based on Lora target tracking is also provided, and the device includes:

[0063] one or more processors; and

[0064] A memory storing computer readable instructions, which, when executed, cause the processor to perform the operations of the method as described above.

[0065] For example, the computer readable instructions, when executed, cause the one or more processors to:

[0066] Expand the internal RF channel of Lora, build a circular array antenna structure, and obtain the modified Lora;

[0067] The modified Lora is installed on the robot body, the signal sent by the tracked object is received, and the arrival time difference positioning is measured through multiple channels to obtain the target angle and relative distance;

[0068] The tracked object is tracked according to the target angle and the relative distance.

[0069] Obviously, those skilled in the art can make various changes and modifications to the present application without departing from the spirit and scope of the present application. Thus, if these modifications and variations of the present application fall within the scope of the claims of the present application and their equivalents, the present application is also intended to include these modifications and variations.

[0070] It should be noted that the present application can be implemented in software and / or a combination of software and hardware, for example, can be implemented using an application specific integrated circuit (ASIC), a general purpose computer or any other similar hardware device. In one embodiment, the software program of the present application can be executed by a processor to implement the steps or functions described above. Similarly, the software program of the present application (including relevant data structures) can be stored in a computer-readable recording medium, for example, a RAM memory, a magnetic or optical drive or a floppy disk and similar devices. In addition, some steps or functions of the present application can be implemented using hardware, for example, as a circuit that cooperates with a processor to perform each step or function.

[0071] In addition, a part of the present application may be applied as a computer program product, such as a computer program instruction, which, when executed by a computer, can call or provide the method and / or technical solution according to the present application through the operation of the computer. The program instruction for calling the method of the present application may be stored in a fixed or removable recording medium, and / or transmitted through a data stream in a broadcast or other signal-bearing medium, and / or stored in a working memory of a computer device that runs according to the program instruction. Here, according to an embodiment of the present application, a device is included, the device including a memory for storing computer program instructions and a processor for executing program instructions, wherein, when the computer program instruction is executed by the processor, the device is triggered to run the method and / or technical solution based on the aforementioned multiple embodiments according to the present application.

[0072] It is obvious to those skilled in the art that the present application is not limited to the details of the above exemplary embodiments, and that the present application can be implemented in other specific forms without departing from the spirit or basic features of the present application. Therefore, from any point of view, the embodiments should be regarded as exemplary and non-restrictive, and the scope of the present application is defined by the appended claims rather than the above description, and it is intended that all changes falling within the meaning and scope of the equivalent elements of the claims are included in the present application. Any figure mark in the claims should not be regarded as limiting the claims involved. In addition, it is obvious that the word "comprising" does not exclude other units or steps, and the singular does not exclude the plural. The words first, second, etc. are used to indicate names, and do not indicate any particular order.

Claims

1. A method for tracking a target based on Lora, characterized in that: The method comprises: Expand the internal RF channel of Lora, build a circular array antenna structure, and obtain the modified Lora; The modified Lora is installed on the robot body, the signal sent by the tracked object is received, and the arrival time difference positioning is measured through multiple channels to obtain the target angle and relative distance; Tracking the tracked object according to the target angle and relative distance; Among them, the measurement of arrival time difference positioning through multiple channels includes: The multi-channel data of the tracked object is collected through the constructed circular array antenna structure, and the arrival time difference positioning is measured based on the collected data; The measurement of arrival time difference positioning is performed based on the collected data, including: In the arrival time difference positioning algorithm, the array direction corresponding to the antenna in the rotating circular array antenna structure when it arrives at the preset time is recorded, and the angle reached within the preset time is measured to obtain the target angle corresponding to the rotated antenna; The relative distance is obtained according to the array direction and the angle of arrival.

2. The method according to claim 1, characterized in that Expand the internal RF channel of Lora and build a circular array antenna structure, including: The base station RF channels are reused through the internal RF switch of Lora to expand the number of external antennas; A circular array antenna structure is constructed based on an extended external antenna.

3. The method according to claim 1, characterized in that In the arrival time difference positioning algorithm, the array direction corresponding to the antenna in the rotating circular array antenna structure when it arrives at the preset time is recorded, and the angle reached within the preset time is measured to obtain the target angle corresponding to the rotated antenna, including: In the arrival time difference positioning algorithm, the first flight time of the first antenna collected and the array direction are recorded; When the nth antenna in the circular array antenna structure is measured at the nth flight time, the target angle to which the array is rotated is obtained, where n=2, 3, ...

4. The method according to claim 3, characterized in that The method comprises: The distance difference between the first antenna and the nth antenna from the first flight time to the nth flight time is calculated according to the array direction and the target angle.

5. The method according to claim 3, characterized in that: After obtaining the target angle to which the array is rotated, it includes: A step factor is selected, and the target angle is iteratively updated according to the step factor, the acquired array direction, the initialized angle, and the offset.

6. The method according to claim 1, characterized in that Tracking the tracked object according to the target angle and the relative distance includes: By rotating the array antenna structure, the target angle and relative distance between each antenna in the annular array antenna structure and the first antenna are obtained, and the tracked object is tracked according to the target angle and relative distance of each group.

7. A device based on Lora target tracking, characterized in that: The device comprises: one or more processors; and A memory storing computer readable instructions which, when executed, cause the processor to perform the operations of the method as claimed in any one of claims 1 to 6.

8. A computer-readable medium having computer-readable instructions stored thereon, wherein the computer-readable instructions can be executed by a processor to implement the method according to any one of claims 1 to 6.

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