Mobile equipment indoor positioning method and system based on optical synchronization ultrasonic one-way distance measurement

Abstract

The invention belongs to the technical field of indoor positioning, and relates to a mobile equipment indoor positioning method and system for optical synchronization ultrasonic one-way ranging. The following steps are executed on each mobile device: S1: judging whether a positioning permission is obtained; s2, if yes, executing a positioning task, synchronously establishing an application list, writing an authority distribution response, broadcasting the response after the task is finished, emptying a positioning state, outputting coordinates, broadcasting an authority application, and returning to S1; and if not, broadcasting the permission application, and returning to S1. According to the invention, high-precision and low-delay positioning of the indoor mobile equipment cluster can be realized.

Description

TECHNICAL FIELD

[0001] The present application belongs to the technical field of indoor positioning, and particularly relates to a mobile device indoor positioning method and system based on light-synchronized ultrasonic one-way ranging. BACKGROUND

[0002] Indoor positioning technology (IPS) refers to a technology system for obtaining absolute coordinates or relative positions of a mobile device (such as an AGV, a drone or a handheld terminal) in an indoor environment (such as a factory workshop, a warehouse, an underground garage or an office building) without GNSS (such as GPS or Beidou) signal coverage or signal severe attenuation, so as to realize positioning, tracking and navigation. The core requirement is to balance the positioning accuracy, real-time performance (refresh frequency), stability and scalability in a complex indoor scene, so as to meet the fine operation requirements (such as AGV precise docking, drone inspection path planning and personnel and material tracking) in the fields of industrial production, logistics and public services.

[0003] Common indoor positioning schemes include UWB, RF+ultrasonic TDoA, pure vision / SLAM, etc. Traditional ultrasonic echo ranging relies on target reflection, is easily affected by material and multipath, and has large round-trip attenuation. A centralized time slot / polling system has large time delay and limited throughput in a multi-device and multi-base station scene. In addition, there are obstructions and reflections in a complex indoor environment, making it difficult to distinguish direct waves. Existing systems mostly use time domain thresholds or centralized scheduling to alleviate the problem, but it is still difficult to simultaneously meet the requirements of high accuracy, low time delay, stable refresh and scalability under the conditions of no central control, no global clock, devices joining and leaving at any time. SUMMARY

[0004] The technical problem to be solved by the present application is that in a complex indoor environment without a center and GNSS, existing ultrasonic / light cooperative positioning schemes are difficult to simultaneously achieve high-quality one-way ranging and output stable, low-latency and scalable absolute coordinates under reflection, obstruction and multi-device concurrency.

[0005] To solve the above technical problems, the present application realizes the following technical scheme: In a first aspect, three mobile device indoor positioning methods based on light-synchronized ultrasonic one-way ranging are proposed. The first light-synchronized ultrasonic one-way ranging mobile device indoor positioning method comprises the following steps: S1: judging whether the mobile device has obtained the positioning permission; S2: if the mobile device has obtained the positioning permission, executing the positioning task, synchronously executing task A during the execution of the positioning task, executing task B and task C in sequence at the end of the positioning task, and returning to S1; task A comprises: establishing an application list, and writing the application list into the permission allocation response; task B comprises: broadcasting the permission allocation response, clearing the permission state, and outputting the positioning coordinates; task C comprises: broadcasting the positioning permission application; if the mobile device has not obtained the positioning permission, broadcasting the positioning permission application, and returning to S1; the execution of the positioning task comprises the following steps: transmitting infrared light and ultrasonic waves to the positioning base station; the infrared light contains the device number of the mobile device, and the beam angle of the infrared light is less than the beam angle of the ultrasonic waves; the positioning base station is used for starting timing when the infrared light arrives, ending timing when the ultrasonic waves arrive, and sending feedback information to each mobile device in the wireless signal coverage range; the feedback information comprises: the one-way flight time of the ultrasonic waves, the base station coordinates, and the device number; the one-way flight time of the ultrasonic waves is equal to the timing end time minus the timing start time; judging whether the device number in each feedback information is consistent with the device number of the mobile device; if not, discarding the feedback information; if yes, keeping the feedback information; obtaining the two-dimensional plane distance between the mobile device and the positioning base station corresponding to each feedback information, and establishing a plane distance set; judging whether the two-dimensional plane distance greater than or equal to the first threshold value can be screened from the plane distance set; if yes, taking the base station coordinates of the positioning base station corresponding to any screened two-dimensional plane distance as the positioning coordinates of the mobile device; if not, obtaining the positioning coordinates of the mobile device through three-edge solution.

[0006] The second mobile device indoor positioning method of one-way ranging of light-synchronized ultrasonic wave is: S1: numbering each mobile device according to the starting sequence of the device; S2: dividing each second duration into multiple equal continuous time slices on the time axis, and cyclically numbering the time slices according to the number of mobile devices; S3: sending a control signal and the current time slice number to each mobile device; the control signal is used to control the mobile device to determine whether the number of the mobile device matches the number of the current time slice, if yes, broadcast a feedback signal and execute a positioning task, and broadcast a task end signal when the positioning task ends, if no, enter a waiting state; S4: when receiving the task end signal or not receiving the feedback signal, jump to the next time slice and return to S3; when a mobile device is added or removed indoors, return to S1; the positioning task includes the following steps: emitting infrared light and ultrasonic wave to the positioning base station; the infrared light contains the device number of the mobile device, and the infrared beam angle is less than the ultrasonic beam angle; the positioning base station is used to start timing when the infrared light arrives, end timing when the ultrasonic wave arrives, and send feedback information to each mobile device within the wireless signal coverage range; the feedback information includes: one-way flight time of ultrasonic wave, base station coordinates and device number; one-way flight time of ultrasonic wave = timing end time - timing start time; determining whether the device number in each feedback information is consistent with the device number of the mobile device; if not, discarding the feedback information; if yes, retaining the feedback information; obtaining the two-dimensional plane distance between the mobile device and the positioning base station corresponding to each feedback information, and establishing a plane distance set; determining whether a two-dimensional plane distance greater than or equal to a first threshold value can be selected from the plane distance set; if yes, taking the base station coordinates of the positioning base station corresponding to any selected two-dimensional plane distance as the positioning coordinates of the mobile device; if no, obtaining the positioning coordinates of the mobile device through three-edge solution.

[0007] The third light-synchronized ultrasonic one-way ranging mobile device indoor positioning method comprises the following steps: S1: broadcasting a channel occupation application of the mobile device; the channel occupation application comprises a device number of the mobile device; S2: establishing a polling queue according to a priority of a positioning task and / or a time sequence of the channel occupation application; S3: obtaining a waiting time according to a channel time length and a position of the channel number of the mobile device in the polling queue; S4: after the waiting time ends, performing the positioning task and broadcasting a positioning task start time, adjusting the device number of the mobile device to the end of the polling queue after the positioning task is completed, and returning to S1; the positioning task comprises the following steps: transmitting infrared light and ultrasonic waves to a positioning base station; the infrared light comprises the device number of the mobile device, and an infrared beam angle is less than an ultrasonic beam angle; the positioning base station is used for starting timing when the infrared light arrives, ending timing when the ultrasonic wave arrives, and sending feedback information to each mobile device in a wireless signal coverage range; the feedback information comprises a one-way flight time of the ultrasonic wave, a base station coordinate and a device number; the one-way flight time of the ultrasonic wave is equal to the timing end time minus the timing start time; determining whether the device number in each feedback information is consistent with the device number of the mobile device; if not, discarding the feedback information; if yes, retaining the feedback information; obtaining a two-dimensional plane distance between the mobile device and the positioning base station corresponding to each feedback information, and establishing a plane distance set; determining whether a two-dimensional plane distance greater than or equal to a first threshold value can be screened from the plane distance set; if yes, taking the base station coordinate of the positioning base station corresponding to any screened two-dimensional plane distance as a positioning coordinate of the mobile device; if not, obtaining the positioning coordinate of the mobile device through three-edge solution.

[0008] In a second aspect, three light-synchronized ultrasonic one-way ranging mobile device indoor positioning systems are provided. The first light-synchronous ultrasonic one-way ranging mobile device indoor positioning system comprises a positioning device installed on each mobile device and a plurality of fixedly arranged positioning base stations. The positioning device comprises an analysis module for determining whether the mobile device has obtained positioning permission; a first task execution module for executing a positioning task under the condition that the mobile device has obtained positioning permission; a second task execution module for synchronously executing task A during the execution of the positioning task; task A comprises establishing an application list and writing the application list into a permission allocation response; a third task execution module for sequentially executing task B and task C at the end of the positioning task; task B comprises broadcasting the permission allocation response, clearing the permission state and outputting the positioning coordinates; task C comprises broadcasting the positioning permission application; if the positioning permission is not obtained, the positioning permission application is broadcasted; a task execution module for broadcasting the positioning permission application under the condition that the mobile device has not obtained positioning permission; a positioning permission application running control module for controlling the analysis module after the execution of task B and task C or after the broadcasting of the positioning permission application under the condition that the mobile device has not obtained positioning permission; the first task execution module comprises an infrared light emitter for emitting infrared light to the positioning base station; the infrared light contains the device number of the mobile device; an ultrasonic emitter for emitting ultrasonic waves to the positioning base station; the infrared beam angle is less than the ultrasonic beam angle; an information processing unit for determining whether the device number in each feedback information is consistent with the device number of the mobile device; if not, the feedback information is discarded; if yes, the feedback information is retained; a numerical calculation unit for obtaining the two-dimensional plane distance between the mobile device and each feedback information corresponding positioning base station and establishing a plane distance set; an analysis unit for determining whether the two-dimensional plane distance greater than or equal to the first threshold value can be screened from the plane distance set; a first coordinate acquisition unit for taking the base station coordinates of any screened two-dimensional plane distance corresponding positioning base station as the positioning coordinates of the mobile device under the condition that the two-dimensional plane distance greater than or equal to the first threshold value can be screened from the plane distance set; a second coordinate acquisition unit for obtaining the positioning coordinates of the mobile device through three-edge solution under the condition that the two-dimensional plane distance greater than or equal to the first threshold value cannot be screened from the plane distance set; the positioning base station comprises a timer for starting timing at the moment when the infrared light arrives and ending timing at the moment when the ultrasonic wave arrives; an information sending module for sending feedback information to each mobile device within the wireless signal coverage range; the feedback information comprises the one-way flight time of the ultrasonic wave, the base station coordinates and the device number; the one-way flight time of the ultrasonic wave = the timing end time - the timing start time.

[0009] The second kind of mobile equipment indoor positioning system of optical synchronization ultrasonic one-way ranging includes: a controller, a positioning device installed on each mobile equipment and a plurality of positioning base stations fixedly arranged; the controller includes: a first numbering setting module for numbering each mobile equipment according to the starting sequence of the equipment; a second numbering setting module for dividing each second duration into a plurality of equal continuous time slices on a time axis and cyclically numbering the time slices according to the number of mobile equipment; a signal sending module for sending a control signal and the number of the current time slice to each mobile equipment; the control signal is used to control the mobile equipment to judge whether the number of the mobile equipment matches the number of the current time slice, if yes, broadcast a feedback signal and perform a positioning task, broadcast a task end signal when the positioning task ends, if no, enter a waiting state; a running control module for jumping to the next time slice when receiving the task end signal or not receiving the feedback signal and controlling the signal sending module to work, controlling the first numbering setting module to work when indoor mobile equipment is added or reduced; the positioning device includes: an infrared light emitter for emitting infrared light to the positioning base station; the infrared light contains the number of the mobile equipment; an ultrasonic wave emitter for emitting ultrasonic waves to the positioning base station; the beam angle of the infrared light is less than or equal to the beam angle of the ultrasonic wave; an information processing unit for judging whether the number of the mobile equipment in each feedback information is consistent with the number of the mobile equipment; if not, discarding the feedback information; if yes, retaining the feedback information; a numerical calculation unit for obtaining the two-dimensional plane distance between the mobile equipment and each feedback information corresponding positioning base station and establishing a plane distance set; an analysis unit for judging whether the two-dimensional plane distance greater than or equal to a first threshold value can be filtered from the plane distance set; a first coordinate acquisition unit for taking the base station coordinate of any filtered two-dimensional plane distance corresponding positioning base station as the positioning coordinate of the mobile equipment under the condition that the two-dimensional plane distance greater than or equal to the first threshold value can be filtered from the plane distance set; a second coordinate acquisition unit for obtaining the positioning coordinate of the mobile equipment through three-edge solution under the condition that the two-dimensional plane distance greater than or equal to the first threshold value cannot be filtered from the plane distance set; the positioning base station includes: a timer for starting timing when the infrared light arrives and ending timing when the ultrasonic wave arrives; an information sending module for sending feedback information to each mobile equipment within the range of wireless signal coverage; the feedback information includes: the one-way flight time of the ultrasonic wave, the base station coordinate and the number of the equipment; the one-way flight time of the ultrasonic wave = timing end time - timing start time.

[0010] The third mobile device indoor positioning system based on optical synchronization ultrasonic one-way ranging comprises a positioning device installed on each mobile device and a plurality of positioning base stations fixedly arranged; the positioning device comprises: a channel occupation application module for broadcasting a channel occupation application of the mobile device; the channel occupation application comprises a device number of the mobile device; a polling queue establishing module for establishing a polling queue according to a priority of a positioning task and / or a time sequence of the channel occupation application; a waiting time length obtaining module for obtaining a waiting time length according to a channel time length and a bit of the mobile device in the polling queue; a positioning task executing module for executing the positioning task and broadcasting a positioning task starting time after the waiting time length ends; a running control module for adjusting the device number of the mobile device to the end of the polling queue after the positioning task is completed and controlling the channel occupation application module to work; the positioning task executing module comprises: an infrared light emitter for emitting infrared light to the positioning base station; the infrared light comprises the device number of the mobile device; an ultrasonic wave emitter for emitting ultrasonic waves to the positioning base station; an infrared light beam angle is less than an ultrasonic wave beam angle; an information processing unit for judging whether the device number in each feedback information is consistent with the device number of the mobile device; if not, the feedback information is discarded; if yes, the feedback information is reserved; a numerical value calculation unit for obtaining two-dimensional plane distances between the mobile device and the positioning base station corresponding to each feedback information and establishing a plane distance set; an analysis unit for judging whether the two-dimensional plane distances greater than or equal to a first threshold value can be screened from the plane distance set; a first coordinate obtaining unit for taking a base station coordinate of the positioning base station corresponding to any screened two-dimensional plane distance as a positioning coordinate of the mobile device under the condition that the two-dimensional plane distances greater than or equal to the first threshold value can be screened from the plane distance set; a second coordinate obtaining unit for obtaining the positioning coordinate of the mobile device through three-edge solution under the condition that the two-dimensional plane distances greater than or equal to the first threshold value cannot be screened from the plane distance set; and the positioning base station comprises: a timer for starting timing when the infrared light arrives and ending timing when the ultrasonic wave arrives; an information sending module for sending feedback information to each mobile device in a wireless signal coverage range; the feedback information comprises: a one-way flight time of the ultrasonic wave, a base station coordinate and a device number; and the one-way flight time of the ultrasonic wave = timing end time - timing start time.

[0011] Compared with the prior art, the present application has the following advantages and beneficial effects: 1. Three methods are used to realize the ordered access of multiple devices: method one is through the closed-loop scheduling logic of "positioning permission judgment, positioning permission application and positioning permission allocation" (steps S1 and tasks A, B and C), the mobile device applies for the list, broadcasts the permission allocation response and applies for the positioning permission; method two is to divide the unit time into equal time slices and number the time slices, and the order of the mobile device executing the positioning task is controlled by matching the time slice number with the mobile device number; method three is to establish a polling queue, determine the waiting time according to the position of the mobile device in the polling queue, and sequentially implement the positioning task, so as to avoid the air collision caused by the simultaneous emission of infrared / ultrasonic signals by multiple devices, significantly improve the system scalability, support multiple mobile devices concurrent positioning and not affect the positioning stability.

[0012] 2. The positioning task is constrained by the infrared beam angle and the ultrasonic beam angle, which can physically preferentially capture the direct wave and suppress the multipath interference and false triggering caused by wall reflection, greatly improve the effectiveness and reliability of the feedback information; relying on the local timing method of the positioning base station "infrared light timing starting point and ultrasonic wave timing ending point", the mobile device can synchronously receive the feedback information of multiple base stations after one-time emission, avoid the redundant overhead of centralized polling, and significantly reduce the positioning time delay; by establishing a two-dimensional plane distance set, the two-dimensional plane distances meeting the conditions are preferentially selected and the corresponding base station coordinates are directly used as the positioning results, the rapidity and stability of near-field positioning are considered, and when the selected coordinates are not obtained, the coordinates are obtained through trilateration, the positioning accuracy of far-field positioning is guaranteed, and combined with the accurate input of feedback information such as base station number, timing length and base station coordinates, the high-precision, low-latency and high-reliability of mobile device indoor positioning in a GNSS-free environment are finally realized, and the positioning needs of mobile robots, AGVs and other devices in industrial scenarios are fully met. BRIEF DESCRIPTION OF DRAWINGS

[0013] The drawings described herein are used to provide further understanding of the embodiments of the present application, constitute a part of the present application, and do not constitute a limitation on the embodiments of the present application. In the drawings: Figure 1 A flowchart of a mobile device indoor positioning method of a light-synchronized ultrasonic one-way ranging provided for embodiment 1 of the present application is shown in the figure; Figure 2 A specific execution flowchart of the positioning task provided for embodiment 1 of the present application is shown in the figure; Figure 3 A specific execution flowchart of the positioning task provided for embodiment 1 of the present application is shown in the figure; Figure 4 A flowchart of a mobile device indoor positioning method of a light-synchronized ultrasonic one-way ranging provided for embodiment 2 of the present application is shown in the figure; Figure 5A flow chart of a mobile device indoor positioning method based on a light-synchronized ultrasonic one-way ranging of embodiment 3 of the present application.

[0014] Markings in the drawings and corresponding names of parts: 1-positioning base station; 2-positioning device. DETAILED DESCRIPTION

[0015] In order to make the objects, technical solutions and advantages of the present application clearer, further detailed description will be made to the present application with reference to the embodiments, the illustrative embodiments of the present application and the description thereof are only used to explain the present application, and do not limit the present application. The embodiments described below are part of the embodiments of the present application, but not all the embodiments. Based on the embodiments in the present application, all other embodiments obtained by those skilled in the art without creative work fall within the scope of protection of the present application.

[0016] In the following description, a large number of specific details are set forth in order to provide a thorough understanding of the present application. However, it will be apparent to one of ordinary skill in the art that the present application can be practiced without these specific details. In other embodiments, well-known structures, materials or methods have not been specifically described in order to avoid obscuring the present application. The materials, instruments and reagents used in the following embodiments, unless otherwise specified, can be obtained from commercial channels. The technical means used in the embodiments, unless otherwise specified, are conventional means known to those skilled in the art.

[0017] In addition, the terms "first", "second" are only used for descriptive purposes, and cannot be understood as indicating or implying relative importance or implicitly indicating the number of the indicated technical features. Therefore, the features defined with "first", "second" can explicitly or implicitly include one or more of the features. In the description of the present application, the meaning of "a plurality of" is two or more, unless otherwise specifically limited.

[0018] Embodiment 1: A mobile device indoor positioning method of light-synchronized ultrasonic one-way ranging is provided, which is applicable to a mobile device cluster composed of multiple mobile devices, relies on a positioning device installed on the mobile device and multiple positioning base stations fixedly installed on the indoor ceiling, and has the overall technical route that: the positioning device transmits infrared light and ultrasonic waves in turn in each positioning period; the positioning base station takes the time when the infrared light is received as the starting point of timing and the time when the ultrasonic wave is received as the ending point of timing, locally calculates the one-way flight time of the positioning period, and returns an observation frame containing the base station number and the three-dimensional coordinates of the base station to the positioning device; the positioning device, based on environmental parameters such as temperature and humidity, eliminates the influence of the height difference between the base station and the device on the one-way flight time, and performs, in the plane, the "near-base station direct taking" (when the device is located near the base station directly below) or the non-collinear maximum area optimization trilateration in priority, and outputs the absolute coordinates; wherein the emission direction and the beam angle of the synchronous light are the same as the emission direction and the beam angle of the ultrasonic wave, and the infrared beam angle is less than or equal to the ultrasonic beam angle, so as to ensure the priority of capturing the direct wave and inhibiting reflection and false triggering.

[0019] The method is executed on each mobile device Figure 1 The following steps are shown: Step 1: Determine whether the mobile device has obtained the positioning permission.

[0020] Since the method is aimed at the indoor positioning scene of multiple mobile devices concurrent without a central controller, in order to simultaneously ensure the order, real-time performance and reliability of positioning, the "unique permission certificate" mechanism is used to solve the resource competition problem of shared air interface. Specifically, the positioning device needs to transmit infrared and ultrasonic signals, and the positioning base station needs to return the one-way flight time through the wireless link. These signals all rely on public air interface transmission. If there is no permission constraint, multiple mobile devices may transmit signals at the same time, resulting in superimposed interference of infrared light and ultrasonic wave, false triggering of the base station, or conflict of wireless return packets, which directly destroys the accuracy of ranging and the continuity of positioning. The positioning permission, as an "air interface use right authorization certificate", only allows the mobile device that has obtained the positioning permission to perform positioning in the exclusive positioning period, and the mobile device that has not obtained the positioning permission is not allowed to perform positioning, but remains in the state of waiting for obtaining the positioning permission, thereby avoiding signal collision from the source and improving channel utilization and positioning stability.

[0021] Therefore, each mobile device that wants to perform a positioning task needs to determine whether it has obtained the positioning permission. The determination method is: Step 1.1: Continuously scan the positioning permission application or permission allocation response broadcast by the remaining mobile devices at a fixed frequency.

[0022] Step 1.2: Analysis of scanning results. If the positioning permission application or the permission assignment response is not scanned for multiple times, the permission state of the mobile device is set as having obtained the positioning permission. If the permission assignment response is scanned, the application list in the permission assignment response is read; it is judged whether the positioning permission application of the mobile device is located at the head of the application list; if yes, the permission state of the mobile device is set as having obtained the positioning permission, and if no, the permission state of the mobile device is set as not having obtained the positioning permission.

[0023] It should be noted in advance that: 1. The method is for the current positioning period, and the method described in the embodiment is also performed in a positioning period before the current positioning period. 2. The positioning permission needs to be obtained by the mobile device through initiating the positioning permission application. The mobile device having obtained the positioning permission needs to release the positioning permission after performing the current positioning task, and assign the use object (mobile device) in the next positioning period for the positioning permission through the permission assignment response. Based on the above explanation, the positioning permission application corresponding to step 1.1 is in the current positioning period, and the permission assignment response is from the last positioning period.

[0024] In the current positioning period, each mobile device scans whether other devices broadcast the positioning permission application or the permission assignment response through the 2.4G wireless module at a fixed frequency (such as 10 ms / time). The purpose of broadcasting the positioning permission request is to declare the positioning demand of the mobile device to other devices in the room, and the purpose of broadcasting the permission assignment response is to ensure that multiple devices perform positioning in order and avoid signal collision. If the positioning permission application (other mobile devices do not broadcast the positioning permission application) is not scanned for multiple times (such as 3 times), it indicates that only the mobile device has the positioning demand in the current room, and at this time, the mobile device naturally obtains the positioning permission. If the permission assignment response is not scanned for multiple times (such as 3 times), it indicates that there is only one mobile device (the mobile device) in the current room, because the scheduling of the positioning permission depends on the interactive closed loop of "application-assignment". As long as there are two or more mobile devices in the room, any mobile device broadcasting the positioning permission application will be received by other mobile devices, and there will be no completely silent state. At this time, the mobile device naturally obtains the positioning permission.

[0025] Further, if a permission assignment response is scanned, it indicates that a mobile device has completed the positioning task in the previous positioning period, released the positioning permission, and assigned the use object of the positioning permission through the form of broadcasting the assignment response. Therefore, the application list in the permission assignment response needs to be read (the application list is an "order table" of multiple mobile devices performing positioning tasks, and the method of creating the application list will be explained later). After reading the application list, it needs to be judged whether the positioning permission application of the mobile device is located at the head of the application list. If the positioning permission application of the mobile device is located at the head of the application list, it indicates that the mobile device is the earliest to apply for the positioning permission and has the highest use weight, at which time the permission state of the mobile device can be set to have obtained the positioning permission; on the contrary, if the positioning permission application of the mobile device is not located at the head of the application list, it needs to be queued and waited, at which time the permission state of the mobile device needs to be set to not have obtained the positioning permission.

[0026] Step 2: If the positioning permission is obtained, the positioning task is performed, and the task A is synchronously performed in the process of performing the positioning task; the tasks B and C are sequentially performed at the end of the positioning task, and the step 1 is returned. If the positioning permission is not obtained, the positioning permission application is broadcasted, and the step 1 is returned.

[0027] Among them, the execution content of the task A is to establish the application list and write the application list into the permission assignment response; the execution content of the task B is to broadcast the permission assignment response, clear the permission state and output the positioning coordinates; and the execution content of the task C is to broadcast the positioning permission application.

[0028] For the mobile device that has obtained the positioning permission, in addition to performing the positioning task, it also needs to prepare for maintaining the task execution order in the next positioning period, that is, to establish the application list and write the application list into the permission assignment response. After performing the positioning task, the application list needs to be broadcasted to other mobile devices together with the permission assignment response; since the positioning permission is released after the positioning task is performed, the positioning permission state needs to be cleared, and the positioning coordinates are outputted as the task execution result. In addition, the mobile device also needs to broadcast the positioning permission request in order to obtain the permission to perform the next positioning task.

[0029] Next, the positioning task described in step 2 is further explained in detail. Based on the above explanation of the overall technical route of the method, the overall flow of the positioning task is: the positioning device transmits the infrared synchronization light → the positioning device waits for a fixed microsecond delay → the positioning device transmits the ultrasonic wave → the positioning base station obtains the one-way flight time of the ultrasonic wave → the positioning base station transmits the one-way flight time and its own coordinates to the positioning device through the wireless link → the positioning device converges the data of the positioning base station and deducts the inherent delay → the positioning device calculates the sound speed combined with the temperature and humidity and converts the space distance → the positioning device eliminates the height difference to obtain the plane distance → the positioning device obtains the positioning coordinates based on the plane distance. Specifically, the positioning task includesFigure 2 The following steps are shown: Step 2.1: Emitting infrared light and ultrasonic waves to the positioning base station.

[0030] The infrared propagation speed is close to the speed of light (3 x 10 8 m / s), and the propagation time can be ignored (less than 1 ns) in indoor scenarios, which can be used as a "global synchronization starting point"; the ultrasonic wave propagation speed is slower (330-360 m / s), and its flight time is proportional to the distance, which is suitable for distance measurement. Due to the problems such as multi-path reflection (pseudo-signal generated by wall / object reflection), propagation attenuation (large loss in round trip), and false triggering (non-target signal triggering the positioning base station) in indoor ultrasonic wave propagation, infrared light is used to provide a synchronization timing reference, perform spatial gate screening, and trigger the positioning base station response - on the one hand, the base station is unified to start timing at the time of receiving infrared light, ensuring accurate one-way flight time measurement of ultrasonic waves; on the other hand, only the base stations in the effective area directly below the base station are woken up by the narrow beam angle of infrared light, filtering false triggers caused by reflected ultrasonic waves and distant interference signals; on the other hand, the infrared light informs the positioning base station of the source and timing of subsequent ultrasonic signals, avoiding the base station from being unable to identify valid signals due to ultrasonic wave propagation attenuation and superposition, and ensuring the reliability of the distance measurement link.

[0031] The infrared light and ultrasonic waves are emitted by a positioning device installed on a mobile device. The infrared light and ultrasonic waves have a sequence of emission: first, the infrared light emitter (such as a 940nm infrared emitter tube, model R333-A) in the positioning device emits 38kHz, 940nm infrared light (for 10-20μs) to each positioning base station within the infrared light coverage range, serving as a synchronization reference and spatial gate; then, the positioning device waits for a fixed microsecond-level delay (such as 50-100μs), which needs to be calibrated according to the device hardware response speed, to avoid the superposition of infrared light signals and ultrasonic signals; next, the ultrasonic wave emitter (such as a 40kHz ultrasonic emitter, model T40-16) in the positioning device emits a 40kHz ultrasonic pulse (for 50-100μs) to each positioning base station within the ultrasonic wave coverage range; next, the positioning device opens a 20-50ms packet return waiting window, preparing to receive the feedback information returned by each positioning base station.

[0032] It should be noted that: the infrared emitter and the ultrasonic emitter need to be installed in the same direction, and the infrared beam angle ≤ ultrasonic beam angle (preferably infrared beam angle 30°-45°, ultrasonic beam angle 60°-90°), the infrared beam angle is small, which can accurately "aim" the positioning base station in the infrared light coverage area, the ultrasonic beam angle is slightly larger, which can cover the range aimed by the infrared light, the combination of the two forms a "spatial screening", only the positioning base station located in a certain range above the positioning device correctly receives the signal, and through the physical layer constraint to ensure that the "light-gated cone" falls completely within the "ultrasonic main lobe", to preferentially capture the direct wave from the source and suppress the mis-triggering caused by the reflection of light / sound signals on the wall and equipment (explained in detail later).

[0033] The positioning base station is used to start timing when the infrared light arrives, end timing when the ultrasonic wave arrives, and send feedback information positioning to each mobile device located within the defined range. The base station is fixedly installed on the indoor ceiling (such as a 100㎡ factory workshop, 7 positioning base stations are uniformly arranged on the ceiling). After the installation of the positioning base station, a laser range finder is used to measure and record the three-dimensional coordinates (x, y, z) of each base station, and the base station is connected to the upper computer through a serial port. The AT command is used to write "base station number (such as 01-10), three-dimensional coordinates (such as base station 01: x=2.0m, y=3.0m, z=3.5m), and correction parameter of one-way flight time" into the EEPROM (power-off data loss storage module) of the base station, which is used to align the timing deviation of different base stations. In addition, it is also necessary to agree that the field order of the feedback information returned by the positioning base station is "identification header (such as 0xAA), base station number, timing duration (i.e. one-way flight time, unit: μs), horizontal coordinate x, vertical coordinate y, normal coordinate z, and device number of the mobile device carried in the infrared light".

[0034] It should be noted that: the above-mentioned correction parameter of one-way flight time is obtained in the following way: in a standard environment (such as temperature 25℃, humidity 50%, no obstruction), the difference between the measured one-way flight time and the theoretical one-way flight time of each positioning base station is measured, and the difference is taken as the correction parameter of one-way flight time and is fixed to the positioning base station; in addition, each positioning base station has a unique and independent correction parameter, which is a inherent characteristic determined by the hardware properties of the positioning base station (such as individual differences of components), and needs to be calibrated and fixed separately, and cannot be universal.

[0035] When the positioning base station captures the infrared light through the infrared light receiving module (such as TSOP1838), the local timer is started immediately; when the ultrasonic receiving module (such as RCWL-1640 / 9620) captures the ultrasonic wave, the timer is stopped, and the one-way flight time of the ultrasonic wave is obtained; then, the positioning base station returns the observation frame containing the "identification header, base station number, one-way flight time, and base station coordinates and device number" as feedback information to the positioning device through the ESP-Now wireless link (low latency, high robustness); the antenna of the positioning base station (downward radiating ceramic antenna) needs to be optimized for downward radiation (gain ≥ 5dBi) to improve the success rate of wireless return. For example, a positioning base station receives infrared light and starts the timer, receives ultrasonic waves after 125μs, and the timer stops (one-way flight time = 125μs); then the positioning base station returns the feedback information "0xAA|03|125|2500|3200|3500|02" (x = 2500mm, y = 3200mm, z = 3500mm) to the positioning device.

[0036] It should be noted that: 1. Each positioning base station needs to complete timing independently to avoid the signal transmission delay of centralized timing, while ensuring the integrity of the returned data. 2. The feedback information returned by the positioning base station is only received by the mobile device located within the wireless signal coverage range and with the same device number, because: As shown in Figure 3 , the positioning base station 1 is mounted on the ceiling, and the positioning device 2 is installed on the mobile device on the ground, and the two are in a "up-down relative" relationship. The infrared beam angle and the ultrasonic beam angle can be understood as the "cone-shaped range of signal propagation". The smaller the beam angle, the narrower the cone, and the more concentrated the signal coverage area; the larger the beam angle, the wider the cone, and the wider the coverage area. The combination of the infrared beam angle and the ultrasonic beam angle forms a "spatial screening", only the positioning base station 1 within the infrared light coverage range is activated, the activated positioning base station 1 receives the ultrasonic wave, and after information processing, the feedback information is returned to the positioning device in the form of wireless signal. Including the following two steps: (1) Infrared beam angle wake-up positioning base station 1 - Infrared beam angle is small (such as 30°), forming a "narrow conical" propagation range. Because positioning base station 2 is installed on the ceiling, the infrared light will only cover the "narrow conical" range vertically upwards. For example, when the indoor space height is 3 meters, the coverage diameter of the infrared light with a beam angle of 30° is approximately 3 x tan(15°) x 2 = 1.6 meters. Only when positioning base station 1 is just in the infrared light circular area, the infrared light emitted by positioning device 2 can be received by positioning base station 1, which can be understood as that positioning base station 1 passes the "position authentication" of positioning device 2, and positioning base station 1 is successfully "woken up" and prepares to receive the subsequent ultrasonic wave. If positioning base station 1 is not in the infrared light circular area (such as 2 meters away from the side of the base station), the infrared light will be filtered by the field of view angle of the infrared light receiver or the intensity will be attenuated to the extent that it cannot trigger positioning base station 1, which is equivalent to that positioning base station 1 does not pass the "position authentication" of positioning device 2, and positioning base station 1 is not successfully "woken up".

[0037] (2) Ultrasonic beam angle matching position authentication - After emitting infrared light, positioning device 2 will emit ultrasonic wave immediately. The ultrasonic beam angle is large (such as 60°), forming a "wide conical" propagation range. Since the infrared beam angle is less than the ultrasonic beam angle, the "wide conical" propagation range can completely contain the above-mentioned "narrow conical" propagation range (for example, when the indoor space height is 3 meters, the coverage diameter of the ultrasonic wave with a beam angle of 60° is approximately 3 x tan(30°) x 2 = 3.46 meters). That is, as long as positioning base station 1 is in the above-mentioned "narrow conical" propagation range, the ultrasonic wave emitted by positioning device 2 can be received by positioning base station 1. The core role of this step is to ensure that the ultrasonic wave received by positioning base station 1 is the one emitted by positioning device 2 that "wakes up" it, rather than the one emitted by other positioning device 1 or the reflected wave (such as the ultrasonic wave reflected by the wall). If positioning base station 1 is not in the above-mentioned "narrow conical" propagation range, even if the ultrasonic wave emitted by positioning device 2 can propagate to positioning base station 1, because positioning base station 1 is not woken up by infrared light, it will identify the ultrasonic wave as "interference signal" and not do any processing.

[0038] Corresponding to Figure 3In the figure, the receiving surface of the infrared sensing element and the ultrasonic sensing element of the positioning base station 1 is vertically downward; the emitting surface of the transmitting probe (infrared emitter and ultrasonic emitter) of the positioning device 2 is vertically upward. Only the positioning base stations 1 (marked as ③ / ④ / ⑤ in the figure) within the infrared light coverage area will be activated and start timing, and the timing operation will end when the ultrasonic wave is received; the positioning base stations 1 (marked as ① / ② / ⑥ / ⑦ in the figure) outside the infrared light coverage area do not work and are in a silent state. Both infrared rays and ultrasonic waves are straight-line propagation, and the straight-line propagation time is the shortest, and the beam angle of infrared light is smaller than that of ultrasonic waves, which ensures that as long as the infrared sensing element is not affected by reflected light, the influence of ultrasonic wave reflection is naturally filtered out. For the positioning base stations 1 close to the wall, a light shield can be added on the wall side to block the reflected light from the wall, making the reliability higher. In addition, as long as the positioning base stations 1 receiving the infrared signal will receive the ultrasonic signal.

[0039] Step 2.2: Determine whether the device number in each feedback information is consistent with the device number of the mobile device; if not, discard the feedback information; if consistent, keep the feedback information.

[0040] Since all the positioning devices of the mobile devices located within the wireless signal range of the positioning base station can receive the feedback information, and the feedback information carries the device number of the mobile device that previously emitted the infrared light, through the consistency comparison of the device number, each mobile device located within the signal coverage range can accurately learn whether the current feedback information is required.

[0041] Step 2.3: Obtain the two-dimensional plane distance between the mobile device and each positioning base station corresponding to the received feedback information, and establish a plane distance set.

[0042] The purpose of obtaining the two-dimensional plane distance is: 1. Indoor positioning often needs plane coordinates (such as AGV navigation and personnel tracking only pay attention to XY axis), and the height information contained in three-dimensional distance is not the core requirement; 2. Eliminate the interference of height difference and avoid the calculation error caused by the height difference between the base station and the device installation; 3. Simplify the calculation complexity, two-dimensional calculation (such as trilateration) does not need to process the complex matrix operation of three-dimensional coordinates, which is suitable for embedded device computing power and improves the real-time positioning.

[0043] Further, obtaining the two-dimensional plane distance includes the following steps: Step 2.3.1: Subtract the inherent delay of the infrared emitter, the inherent delay of the ultrasonic emitter, the reaction time of the infrared receiving module, and the reaction time of the ultrasonic receiving module from the timing duration to obtain the corrected timing duration.

[0044] The purpose is to eliminate the influence of hardware delay on distance measurement and ensure the accuracy of space distance calculation.

[0045] Step 2.3.2: The speed of the ultrasonic wave is corrected using the Cramer empirical formula to obtain the actual speed of the ultrasonic wave.

[0046] The purpose is to eliminate the influence of environmental factors on distance measurement and further ensure the accuracy of space distance calculation. The Cramer empirical formula is an approximate formula for the speed of sound in "real gas" proposed by Owen Cramer in 1993 in J. Acoust. Soc. Am. It treats air as a "wet, CO2-containing real gas" and directly calculates the speed of sound in air using temperature, relative humidity, atmospheric pressure, and CO2 molar fraction. The uncertainty under normal temperature and pressure is approximately 0.1 ms⁻¹. The formula for calculating the speed of ultrasonic wave in indoor environment using Cramer empirical formula is: c = 331.502 + 0.60355T + 0.0124e⁻⁰.00026P, where c is the corrected actual speed of ultrasonic wave (ms⁻¹), T is the indoor air temperature (℃), e is the indoor water vapor partial pressure (hPa), and P is the total atmospheric pressure (hPa).

[0047] For example, if the current indoor temperature is 28℃ and the humidity is 60%, the ultrasonic wave speed c = 331.502 + 0.60355 × 28 + 0.0124 × 2.34 - 0.00026 × 1013.25 = 331.502 + 16.8994 + 0.0290 - 0.2634 ≈ 348.4.14; The negative base station calculates the timing duration = 125μs, deducts the inherent delay 20μs (including the inherent delay of infrared transmitter and the inherent delay of ultrasonic transmitter), the reaction time of positioning base station 15μs (including the reaction time of infrared receiving module and the reaction time of ultrasonic receiving module) and the correction parameter of single flight time 2μs, and the corrected single flight time of ultrasonic wave is 88μs.

[0048] Step 2.3.3: Calculate the three-dimensional space distance from the mobile device to the positioning base station using the corrected timing duration and the actual speed of the ultrasonic wave.

[0049] Three-dimensional space distance = actual speed of ultrasonic wave × corrected single flight time of ultrasonic wave.

[0050] For example, the three-dimensional space distance d = 349.11m / s × 88 × 10⁻ 6 s ≈ 0.0307m = 30.7cm.

[0051] Step 2.3.4: Obtain the height difference between the positioning base station and the mobile device.

[0052] The purpose is to simplify the positioning solution dimension (indoor scene needs XY plane coordinates), and eliminate the interference of height difference on plane positioning. The specific way is: measuring the installation height of the positioning device in advance (such as the installation height of the device on the AGV is 0.5m), calculating the net height difference Δz = z coordinate of the positioning base station - installation height of the positioning device of each positioning base station.

[0053] Step 2.3.5: Convert three-dimensional space distance to two-dimensional plane distance according to the height difference and Pythagorean theorem.

[0054] According to the Pythagorean theorem, convert the three-dimensional space distance d to the XY plane two-dimensional distance d_xy, the formula is (If d < Δz, it is judged as invalid data, and the positioning base station is eliminated).

[0055] For example, the z coordinate of a certain positioning base station is 3.5m, and the installation height of the positioning device is 0.5m, then the net height difference Δz = 3.0m; the three-dimensional space distance d = 30.7cm (0.307m), because d < Δz, it is judged that the data of the positioning base station is invalid, and it is eliminated; if the calculated three-dimensional space distance d = 2.5m, then the plane two-dimensional distance (no real solution, eliminate); if the calculated three-dimensional space distance d = 3.2m, then the plane two-dimensional distance (valid solution).

[0056] Finally, a plane distance set containing "base station number-two-dimensional plane distance" is formed.

[0057] Step 2.4: Determine whether the two-dimensional plane distance greater than or equal to the first threshold value can be selected from the plane distance set; if yes, execute step 2.5, if no, execute step 2.6.

[0058] Step 2.5: The base station coordinates of any selected two-dimensional plane distance corresponding positioning base station are taken as the positioning coordinates of the mobile device.

[0059] When the mobile device is located directly below the positioning base station, the two-dimensional coordinates (x, y) of the positioning base station and the actual coordinates of the mobile device have little deviation (such as ≤2cm), so the two-dimensional coordinates (x, y) of the positioning base station can be directly taken as the positioning result of the mobile device. The purpose of this step is to improve the refresh speed of near-field positioning (avoid complex calculation), and eliminate the coordinate jump easily appeared in the near-field area trilateration.

[0060] The specific implementation is: traversing the set of plane distances, if the plane two-dimensional distance d_xy of any base station is less than or equal to a first threshold value (the first threshold value can be 50-100 cm, adjusted according to the base station density), it is determined that the device is located in the "directly below the near-field area" of the positioning base station, and the two-dimensional coordinates (x, y) of the positioning base station are directly taken as the positioning coordinates of the mobile device, and the subsequent trilateration is skipped; if there are multiple near-field positioning base stations, the two-dimensional coordinates (x, y) of the positioning base station with the smallest plane two-dimensional distance d_xy are taken as the positioning coordinates of the mobile device.

[0061] According to the plane two-dimensional distance d_xy≤the first threshold value, it is determined that the mobile device is located in the "directly below the near-field area" of the positioning base station, which is mainly based on the following principles: (1) Definition and characteristics of the near-field area: In electromagnetic wave propagation, the near-field area refers to the area close to the radiation source, usually within one wavelength of the radiation source. In this area, the electric field and the magnetic field are independent, and their intensity changes with distance in a complex manner, and decays faster than in the far field. When the plane two-dimensional distance d_xy between the mobile device and the positioning base station is less than or equal to a certain threshold value, it is determined that the device may be in the near-field area of the base station from the distance perspective.

[0062] (2) Relationship between signal propagation characteristics and distance: In the near-field area, the signal strength and propagation characteristics are significantly different from those in the far field. Generally, the signal strength in the near-field area is relatively strong, and due to the close distance, the signal is less affected by environmental factors. When the plane two-dimensional distance d_xy is less than or equal to a certain threshold value, the signal strength, phase, and other characteristics of the positioning base station received by the mobile device may meet the signal propagation characteristics of the near-field area, thereby determining that the mobile device is located in the near-field area of the positioning base station.

[0063] (3) Geometric model and error range of the positioning system: In indoor positioning systems, a corresponding geometric model is usually established to determine the position of the mobile device. According to the position of the positioning base station, the direction of signal propagation, and the time, etc., the distance between the mobile device and the positioning base station can be calculated. Due to measurement errors and various environmental factors, a reasonable threshold value needs to be set to determine whether the device is located in the near-field area directly below the base station. When the calculated plane two-dimensional distance d_xy is within this threshold value, it is considered that the device is in the near-field area directly below the base station.

[0064] Step 2.6: Obtain the positioning coordinates of the mobile device through trilateration.

[0065] Trilateration is a mathematical process that "uses the distances from three (or more) known points to an unknown point to calculate the coordinates of the unknown point".

[0066] The specific implementation steps for obtaining the positioning coordinates of the mobile device through trilateration are: Step 2.6.1: Enumerate all positioning base station combinations that meet the preset conditions.

[0067] The preset condition is that the area of the triangle formed by the three positioning base stations is greater than or equal to a third threshold value (for example, the third threshold value is 1 m 2 ).

[0068] The purpose of this step is to enumerate all combinations of "3 non-collinear base stations". If the area of the triangle formed by three points is ≤ 1 m 2 , it is determined to be collinear.

[0069] Step 2.6.2: Calculate the area of the triangle formed by each positioning base station combination, and select the positioning base station combination with the largest triangle area as the optimal combination.

[0070] The core of selecting the non-collinear three-base station combination with the largest area as the "optimal solution set" is to improve positioning accuracy and avoid geometric degradation risk by using geometric distribution characteristics. The reasons are as follows: (1) The larger the area, the more dispersed the three-base station distribution, the narrower the ranging intersection area, the lower the positioning ambiguity, and the smaller the coordinate error; (2) Large-area combinations can effectively reduce the geometric dilution of precision (GDOP), reduce the influence of individual base station errors and environmental interference on positioning results; (3) Avoiding the failure of solving caused by the collinearity or concentrated distribution of three base stations, avoiding the jump of positioning error, and ensuring the stability of the results.

[0071] Step 2.6.3: Use the base station coordinates of the three positioning base stations in the optimal combination to perform trilateration to obtain the positioning coordinates of the mobile device.

[0072] Let the two-dimensional plane coordinates of positioning base station A be (x1, y1), the two-dimensional plane coordinates of positioning base station B be (x2, y2), the two-dimensional plane coordinates of positioning base station C be (x3, y3), and the two-dimensional plane coordinates of the mobile device P be (x, y). According to the equations "(x-x1)²+(y-y1)²=d A _xy²", "(x-x2)²+(y-y2)²=d B _xy²", and "(x-x3)²+(y-y3)²=d C _xy²", the equations are solved to obtain the (x, y) coordinates of the device. Wherein, d A _xy is the horizontal distance between the mobile device and the positioning base station A in the two-dimensional plane (the positioning plane, such as the XY plane), that is, ignoring the height difference between the mobile device and the positioning base station A, only calculating the straight line distance between the two-dimensional plane projection points; d B _xy is the horizontal distance between the mobile device and the positioning base station B in the two-dimensional positioning plane, and the calculation logic is the same as d A_xy is consistent, only for the straight line distance solution of the planar projection point of the positioning base station B and the mobile device projection point; d C _xy is the horizontal distance between the mobile device and the positioning base station C in the two-dimensional positioning plane, which follows the same planar projection distance calculation rule and corresponds to the horizontal position association of the positioning base station C and the mobile device.

[0073] Further, in task A, the method for establishing the application list is: Step A1: Continuously collect the positioning permission applications broadcast by other mobile devices.

[0074] The positioning permission application contains the identity information of the mobile device.

[0075] Step A2: Sort all collected positioning permission applications in chronological order to establish an application list.

[0076] In summary, the mobile device indoor positioning method of the light-synchronized ultrasonic one-way ranging provided in this embodiment is an indoor absolute coordinate positioning system with "light synchronization trigger-ultrasonic one-way ranging-wireless backhaul" as the main link. Through "cross-medium angle constraint (infrared beam angle ≤ ultrasonic beam angle, and same direction)", it suppresses multipath interference from the source; through "local start and stop timing at the receiving end", it simplifies the link organization; through "robust geometric solution pipeline", it guarantees the positioning accuracy; and through "distributed token + bootstrap fallback", it realizes concurrent scheduling. It can solve the problem that existing ultrasonic / light cooperative positioning schemes cannot simultaneously achieve high-quality one-way ranging and output stable, low-latency, and scalable absolute coordinates in the case of reflection and occlusion and multi-device concurrency in a complex indoor environment without a center and GNSS.

[0077] Embodiment 2: Another mobile device indoor positioning method of light-synchronized ultrasonic one-way ranging is provided. This method is also applicable to a mobile device cluster composed of multiple mobile devices, which relies on a controller, a positioning device installed on a mobile device, and multiple positioning base stations fixedly installed on the indoor ceiling. The overall technical route is: the controller divides the time axis into multiple equal-length continuous time slices, numbers the time slices according to the number of mobile devices, and controls the mobile devices to sequentially perform positioning tasks by matching the time slice number with the mobile device number, thereby avoiding mutual interference between multiple devices.

[0078] The method described in this embodiment includes Figure 4 The following steps are shown: Step 1: Number each mobile device according to the order in which the devices are started.

[0079] It should be noted that the prerequisite of this step is that each mobile device broadcasts its current state signal when it enters the starting state, the controller collects the current state signal of each mobile device in the room in real time, and numbers each mobile device according to the order of signal collection time, to ensure that the mobile device started first has the priority to perform the positioning task. This is also the basis for the controller to maintain the order of tasks among multiple mobile devices.

[0080] Step 2: Divide each second into multiple equal consecutive time slices on the time axis, and number the time slices according to the number of mobile devices.

[0081] The core logic of this step is to first determine the minimum time consumption of a single positioning task (determined by the indoor floor height), and then determine the "time cycle period t cycle " combined with the refresh frequency, and finally match the number of devices to assign each mobile device a time slice to perform the positioning task, to ensure that multiple devices are concurrent without conflict and meet the real-time requirements.

[0082] Based on the core logic of this step, it can be known that: (1) the indoor floor height determines the minimum time consumption of a single positioning task, that is, the higher the floor height, the longer the one-way flight time of the ultrasonic wave, and the greater the minimum time consumption of a single positioning task; (2) the number of mobile devices determines the lower limit of the number of time slices, that is, at least the number of time slices equal to the total number of mobile devices, to ensure that each mobile device can be assigned an independent time slice for performing the positioning task, to avoid signal collision, which is the core of time division multiplexing; (3) the positioning refresh rate is the number of positioning tasks that each mobile device needs to complete in a unit of time (set to 1s in this embodiment), which needs to be implemented through "time slice cycle", and the cycle period needs to be less than or equal to 1 / positioning refresh rate to meet the real-time requirement, and the higher the positioning refresh rate, the shorter the time slice cycle period t cycle .

[0083] The method of dividing each second into multiple equal consecutive time slices on the time axis is as follows: Step 2.1: Obtain the one-way flight time of the ultrasonic wave according to the indoor floor height.

[0084] The propagation speed of ultrasonic wave in indoor air c≈340m / s (which can be corrected by the Cramer formula described in Embodiment 1), and the indoor floor height H is the vertical distance from the ground to the ceiling, so the one-way flight time of the ultrasonic wave t sound =H / c. For example, when the indoor floor height H=3m, t sound =3 / 340≈0.0088s=8.8ms; when the indoor floor height H=5m, t sound =5 / 340≈0.0147s=14.7ms.

[0085] Step 2.2: Obtain the sum of one-way flight time, ultrasonic wave transmission delay time, base station timing time, base station data processing time, base station information feedback time and positioning coordinate acquisition time, to obtain the total time consumption of positioning task.

[0086] In addition to the ultrasonic flight time, the minimum time consumption of a single positioning task also includes "ultrasonic wave transmission delay time, base station timing time, base station data processing time, base station information feedback time and positioning coordinate acquisition time. Therefore, the total time consumption t of positioning task is task = one-way flight time + ultrasonic wave transmission delay time + base station timing time + base station data processing time + base station information feedback time + positioning coordinate acquisition time. For example, when the indoor height H = 3m, the ultrasonic wave transmission delay time is 50us (0.2ms), the base station timing time and data processing time are 5ms in total, the base station information feedback time is 3ms, and the positioning coordinate acquisition time (local calculation time of the positioning device) is 3ms, the total time consumption t of a single positioning task is task = 8.8ms + 0.2ms + 5ms + 3ms + 3ms = 20ms.

[0087] Step 2.3: Calculate the number of time slices according to the total time consumption of positioning task and the expected positioning refresh rate.

[0088] The positioning refresh frequency f (unit: Hz, i.e. positioning times per second) represents "the time required for each mobile device to complete a positioning task", so the time slice cycle period (the total time for all mobile devices to poll once) must be less than or equal to 1 / f, otherwise real-time cannot be met. If the positioning refresh frequency is preset to f = 10Hz (each device positions 10 times per second), then t cycle = 1 / 10 = 0.1s = 100ms.

[0089] In addition, the number of time slices N must also satisfy condition 1: N ≥ M (total number of mobile devices) and condition 2: N × t task ≤ t cycle . Condition 1 ensures that each device is allocated at least one independent time slice to avoid conflicts; condition 2 ensures that the total time for all time slices to poll once is ≤ time slice cycle period, meeting the refresh frequency.

[0090] Combining condition 1 and condition 2, the number of time slices is and N ≥ M, which means that the quotient of t cycle and t task is rounded up.

[0091] Step 2.4: If the number of time slices is less than the number of mobile devices, reduce the positioning refresh rate, return to step 2.3, if the number of time slices is greater than or equal to the number of mobile devices, execute step 2.5.

[0092] If the calculated N < M (i.e., the number of mobile devices exceeds the carrying capacity of the current time slice cycle), the time slice cycle needs to be increased by reducing the positioning refresh rate to accommodate more time slices. Return to step 2.3 to recalculate the number of time slices, and iterate in this way until the number of time slices satisfies conditions 1 and 2 above.

[0093] For example: (1) When the indoor floor height H=3m, the total number of mobile devices M=5, and the positioning refresh frequency f=10Hz, first calculate the total positioning task time t. task =20ms; then calculate the time slice cycle period t. cycle =100ms, next calculate the current number of time slices. And N=5≥M=5, satisfying conditions 1 and 2; finally, calculate the number of time slices per unit time (1s) = 1000ns / 100ms×5 = 50, that is, each mobile device occupies 1 time slice, looping 10 times per second (satisfying 10Hz refresh), with no signal conflict.

[0094] (2) When the indoor floor height H=5m, the total number of mobile devices M=5, and the positioning refresh frequency f=10Hz, first calculate the total positioning task time t. task =30ms; then calculate the time slice cycle period t. cycle =100ms, next calculate the current number of time slices. Furthermore, N=4 < M=5, which does not satisfy condition 1. The positioning refresh rate needs to be adjusted. For example, if the positioning refresh rate is reduced to f=7Hz, the time slice cycle period t needs to be recalculated. cycle =140ms, N=5≥M=5, satisfying conditions 1 and 2; finally, calculate the number of time slices per unit time (1s) =1000ns / 140ms×5≈36, that is, each mobile device occupies 1 time slice, loops 7 times per second (satisfying 10Hz refresh), and there is no signal conflict.

[0095] Step 2.5: Divide the unit time into equal time intervals according to the number of time slices to obtain multiple continuous time slices of equal length.

[0096] Step 3: Send a control signal and the current time slice number to each mobile device.

[0097] The control signal is used to control the mobile device to determine whether the number of the mobile device matches the number of the current time slice. If they match, a feedback signal is broadcast and the positioning task is executed. When the positioning task ends, a task end signal is broadcast. If they do not match, the device enters a waiting state.

[0098] The feedback signal is used to indicate that the mobile device has received the control signal sent by the controller and the number of the current time slice, which is used to remind the controller that the sending of the control signal and the number of the current time slice is successful, and the corresponding mobile device can successfully perform the positioning task. If the controller does not receive the feedback signal, it indicates that the mobile device may not be able to perform the positioning task (such as not starting or device failure, etc.), and the current time slice is skipped, and other mobile devices are re-allocated time slices.

[0099] Step 4: When receiving the task end signal or not receiving the feedback signal, jump to the next time slice and return to step 3; when a mobile device is added or reduced in the room, return to step 1.

[0100] Through the above steps 1 to 4, multi-device cooperative positioning based on central control can be realized, and signal conflict can be avoided. The steps of each mobile device performing the positioning task are the same as the method described in embodiment 1, and this embodiment will not be repeated.

[0101] Embodiment 3: Another mobile device indoor positioning method of light synchronization ultrasonic one-way ranging is provided. This method is also applicable to a mobile device cluster composed of multiple mobile devices, and relies on a positioning device installed on the mobile device and multiple positioning base stations fixedly installed on the indoor ceiling. The overall technical route is: each mobile device establishes a polling queue in a time-first or priority-first manner according to the channel occupation request broadcast by other mobile devices, determines the waiting time according to the position of the mobile device in the polling queue, and sequentially performs the positioning task, thereby avoiding signal overlap and mutual interference of multiple devices.

[0102] The method described in this embodiment includes Figure 5 The following steps are shown: Step 1: Broadcast the channel occupation application of the mobile device.

[0103] The channel occupation application contains the device number of the mobile device, which is set in advance. Each mobile device queues to use the corresponding communication channel of the mobile device, and completes the positioning task within the channel occupation time; the communication channel usage order is determined by establishing a polling queue. Each mobile device broadcasts its channel occupation application to other mobile devices, which is the basis for subsequent establishment of a polling queue.

[0104] Step 2: Establish a polling queue according to the priority of the positioning task and / or the time sequence of the channel occupation application.

[0105] The polling queue of each mobile device considers two priorities: one is the priority of performing positioning task, and the other is the priority of requesting occupation of the channel. The priority of performing positioning task is set in advance according to the demand degree of positioning of the mobile device in the actual project, for example, in the actual project, real-time positioning of mobile device A is required, and positioning of mobile device B is required only at a fixed frequency, then the first priority is set for mobile device A, and the second priority is set for mobile device B; in the case that multiple mobile devices have the same priority, the request order of each mobile device is further determined according to the order of time of applying for occupation of the broadcast channel.

[0106] The polling queue is established based on the above principle, and contains sequentially arranged device numbers and channel occupation time lengths corresponding to each device.

[0107] Step 3: Obtain the waiting time according to the channel time length and the bit order of the channel number of the mobile device in the polling queue.

[0108] It should be noted that the time slice division method described in Embodiment 2 is used to determine the channel occupation time length of each mobile device in advance. The waiting time of the mobile device is , T represents the waiting time, k is the total number of mobile devices before the bit order of the mobile device, i represents the bit order of the i-th mobile device, and ti represents the channel occupation time length of the i-th mobile device. ai

[0109] Step 4: Correct the waiting time of the mobile device according to the positioning task start time broadcast by other mobile devices.

[0110] In the case of no central control, each mobile device relies on its local clock (such as MCU crystal oscillator) for timing, but hardware differences (crystal oscillator accuracy, power supply fluctuation) will cause "clock drift". For example, the local clock of mobile device A is fast (the preset channel time length is 20 ms, and it is considered to end only after 19.5 ms), and the clock of mobile device B is slow (the preset channel time length is 20 ms, and it ends only after 20.3 ms); if no time correction is performed, after multiple cycles, the "expected positioning start time" of mobile device A will be advanced, and the expected positioning start time of mobile device B will be delayed, eventually causing the time channels of the two mobile devices to overlap, and signal collision (infrared light and ultrasonic waves are emitted at the same time).

[0111] Therefore, the mobile device in the waiting time needs to correct the waiting time of the mobile device in real time according to the positioning task start time broadcast by the mobile device that has occupied the current communication channel. The specific steps are as follows: Step 4.1: Continuously collect the positioning task start time broadcast by other mobile devices.

[0112] ​Step 4.2: Obtain the time deviation of the positioning task starting time and the waiting duration.

[0113] Step 4.3: Correct the remaining waiting duration according to the time deviation.

[0114] For example: If there are 5 mobile devices (numbered 1-5) in the room using time division coding positioning, a total of 5 communication channels are configured, and the duration of a single communication channel is 20 ms, with a cycle of 100 ms. The communication channel of mobile device 3 is 3, which needs to start positioning at 40 ms according to the preset rule, and is currently in the waiting timing stage.

[0115] When the local timing of mobile device 3 shows 32 ms, it receives the channel occupation application broadcast by mobile device 2, which clearly marks "communication channel 2, actual starting time 20 ms, channel duration 20 ms". After analyzing the signal, mobile device 3 calculates that communication channel 2 of mobile device 2 is occupied from 20 ms, and has been running for 10 ms at the time of receiving the channel occupation application, and the current actual time should be 30 ms. Comparing its own local timing of 32 ms, mobile device 3 determines that its timing is 2 ms ahead. Based on this deviation, device 3 corrects the remaining waiting duration to 12 ms, and continues to wait according to the corrected timing, and finally starts positioning accurately at the preset time of 40 ms, ensuring that there is no overlap with the time channel of other devices, and ensuring the orderly concurrent of multiple devices.

[0116] Step 5: After the waiting duration ends, execute the positioning task and broadcast the positioning task starting time, and after completing the positioning task, adjust the device number of the mobile device to the end of the polling queue, and return to step 1.

[0117] The above steps 1 to 5 can also achieve multi-device cooperative positioning based on central control, avoiding signal conflict. Among them, each mobile device executes the positioning task in the same way as described in embodiment 1, and this embodiment will not be repeated.

[0118] Embodiment 4: Corresponding to embodiment 1, the present embodiment provides a mobile device indoor positioning system for optical synchronization ultrasonic one-way ranging, comprising: a positioning device installed on each mobile device and a plurality of fixedly arranged positioning base stations; The positioning device comprises: an analysis module for determining whether the mobile device has obtained positioning permission; a first task execution module for executing a positioning task if the mobile device has obtained positioning permission; a second task execution module for synchronously executing task A during the execution of the positioning task; task A comprises: establishing an application list, and writing the application list into a permission allocation response; the third task execution module is configured to sequentially execute task B and task C when the positioning task ends; task B comprises broadcasting a permission allocation response, clearing a permission state, and outputting a positioning coordinate; task C comprises broadcasting a positioning permission application; if the positioning permission is not obtained, the positioning permission application is broadcasted; the fourth task execution module is configured to broadcast the positioning permission application if the mobile device does not obtain the positioning permission the running control module is configured to control the analysis module to work after the execution of task B and task C or after the broadcasting of the positioning permission application if the mobile device does not obtain the positioning permission; the first task execution module comprises: the infrared light emitter is configured to emit infrared light to each positioning base station; the ultrasonic wave emitter is configured to emit ultrasonic waves to each positioning base station; the numerical calculation unit is configured to obtain a two-dimensional plane distance between the mobile device and each positioning base station corresponding to the received feedback information, and establish a plane distance set; the analysis unit is configured to determine whether a two-dimensional plane distance greater than or equal to a first threshold value can be filtered out from the plane distance set; the first coordinate acquisition unit is configured to, if a two-dimensional plane distance greater than or equal to the first threshold value can be filtered out from the plane distance set, take a base station coordinate of a positioning base station corresponding to any filtered two-dimensional plane distance as a positioning coordinate of the mobile device; the second coordinate acquisition unit is configured to, if a two-dimensional plane distance greater than or equal to the first threshold value cannot be filtered out from the plane distance set, obtain a positioning coordinate of the mobile device through trilateration; the positioning base station comprises: the timer is configured to start timing at the moment when the infrared light arrives and end timing at the moment when the ultrasonic wave arrives; the information sending module is configured to send feedback information to each mobile device located within a limited range; the limited range refers to a range defined by an infrared light beam angle below the positioning base station; the infrared light beam angle ≤ the ultrasonic wave beam angle; the feedback information comprises a base station number, a timing duration, and a base station coordinate.

[0119] Further, the analysis module comprises: the signal scanning unit is configured to continuously scan the positioning permission application or the permission allocation response broadcasted by the remaining mobile devices at a fixed frequency; the first permission setting unit is configured to, if the positioning permission application or the permission allocation response is not scanned continuously for multiple times, set the permission state of the mobile device as having obtained the positioning permission; the list reading unit is configured to, if the permission allocation response is scanned, read an application list in the permission allocation response; The analysis control unit is configured to determine whether the positioning permission application of the mobile device is at the head of the application list, control the second permission setting unit to work, and if not, control the third permission setting unit to work. The second permission setting unit is configured to set the permission state of the mobile device as having obtained the positioning permission. The third permission setting unit is configured to set the permission state of the mobile device as not having obtained the positioning permission.

[0120] Further, the task A further comprises: counting the packet return rate of the mobile device; the packet return rate = the number of times of successfully receiving feedback information ÷ the total number of times of emitting infrared light and ultrasonic waves; and the task D further comprises: broadcasting the packet return rate.

[0121] Further, the second task execution module comprises: The signal acquisition unit is configured to continuously acquire the positioning permission application broadcast by other mobile devices; the positioning permission application comprises: the identity information of the mobile device, the expected positioning period and the packet return rate. The list creation unit is configured to sort all the acquired positioning permission applications in chronological order to establish an application list. The data reading unit is configured to sequentially read each positioning permission application in the application list. The data processing unit is configured to mark the positioning permission application with the packet return rate less than the second threshold. The data updating unit is configured to compress the expected positioning period in the marked positioning permission application by a compression ratio to update the application list; the compression ratio = the packet return rate.

[0122] Further, the positioning device further comprises: a time delay control module configured to control the ultrasonic wave emitter to wait for a preset fixed time period after the infrared light emitter emits infrared light to the positioning base station, and control the ultrasonic wave emitter to emit ultrasonic waves to each positioning base station after the waiting is terminated.

[0123] Further, the numerical calculation unit comprises: The time correction sub-unit is configured to deduct the inherent time delay of the infrared emitter, the inherent time delay of the ultrasonic emitter, the reaction time of the infrared receiving module, the reaction time of the ultrasonic receiving module from the timing duration to obtain a corrected timing duration. The speed correction sub-unit is configured to correct the speed of the ultrasonic wave by using the Cramer empirical formula to obtain the actual speed of the ultrasonic wave. The spatial distance calculation sub-unit is configured to calculate the three-dimensional spatial distance from the mobile device to the positioning base station by using the corrected timing duration and the actual speed of the ultrasonic wave. The height difference acquisition sub-unit is configured to acquire the height difference between the positioning base station and the mobile device. A plane distance calculation subunit is configured to convert a three-dimensional space distance into a two-dimensional plane distance according to the height difference and the Pythagorean theorem.

[0124] Further, the second coordinate acquisition unit comprises: A base station combination generation subunit is configured to enumerate all positioning base station combinations that satisfy a preset condition; the preset condition is that the area of a triangle formed by three positioning base stations is greater than or equal to a third threshold value. An optimal combination screening subunit is configured to calculate the area of a triangle formed by each positioning base station combination, and screen a positioning base station combination with the largest triangle area as an optimal combination. A three-side positioning interpretation subunit is configured to perform three-side positioning calculation by using the base station coordinates of the three positioning base stations of the optimal combination, to obtain the positioning coordinates of the mobile device.

[0125] The functions and working principles of the above devices, apparatuses, modules and units can be referred to the corresponding explanation in Embodiment 1, and will not be described herein.

[0126] Embodiment 5: Corresponding to Embodiment 2, another optical synchronization ultrasonic single-pass ranging mobile device indoor positioning system is provided, comprising a controller, a positioning device installed on each mobile device and a plurality of fixedly arranged positioning base stations. The controller comprises: A first numbering setting module is configured to number each mobile device according to the starting sequence of the devices. A second numbering setting module is configured to divide each second duration into a plurality of equal continuous time slices on a time axis, and cyclically number the time slices according to the number of the mobile devices. A signal sending module is configured to send a control signal and the number of the current time slice to each mobile device; the control signal is used to control the mobile device to determine whether the number of the mobile device matches the number of the current time slice, if yes, broadcast a feedback signal and perform a positioning task, and broadcast a task end signal when the positioning task ends, if no, enter a waiting state. A running control module is configured to jump to the next time slice when a task end signal is received or no feedback signal is received, and control the signal sending module to work, and control the first numbering setting module to work when a mobile device is added or removed indoors. The positioning device comprises: An analysis module is configured to determine whether the mobile device has obtained positioning permission. A first task execution module is configured to perform a positioning task under the condition that the mobile device has obtained positioning permission. A second task execution module is configured to synchronously perform a task A during the positioning task; the task A comprises: establishing an application list, and writing the application list into a permission allocation response. the third task execution module is configured to sequentially execute task B and task C when the positioning task ends; task B comprises broadcasting a permission assignment response, clearing a permission state, and outputting a positioning coordinate; task C comprises broadcasting a positioning permission application; if the positioning permission is not obtained, the positioning permission application is broadcasted; the fourth task execution module is configured to broadcast a positioning permission application if the mobile device does not obtain the positioning permission; the running control module is configured to control the analysis module to work after the execution of task B and task C or after the broadcasting of the positioning permission application if the mobile device does not obtain the positioning permission; the first task execution module comprises: the infrared light emitter is configured to emit infrared light to each positioning base station; the ultrasonic wave emitter is configured to emit ultrasonic waves to each positioning base station; the numerical calculation unit is configured to obtain a two-dimensional plane distance between the mobile device and each positioning base station corresponding to the received feedback information, and establish a plane distance set; the analysis unit is configured to determine whether a two-dimensional plane distance greater than or equal to a first threshold value can be filtered out from the plane distance set; the first coordinate acquisition unit is configured to, if a two-dimensional plane distance greater than or equal to the first threshold value can be filtered out from the plane distance set, take a base station coordinate of a positioning base station corresponding to any filtered two-dimensional plane distance as a positioning coordinate of the mobile device; the second coordinate acquisition unit is configured to, if a two-dimensional plane distance greater than or equal to the first threshold value cannot be filtered out from the plane distance set, obtain a positioning coordinate of the mobile device through trilateration; the positioning base station comprises: the timer is configured to start timing at the moment when the infrared light arrives and end timing at the moment when the ultrasonic wave arrives; the information sending module is configured to send feedback information to each mobile device located within a limited range; the limited range refers to a range defined by an infrared light beam angle below the positioning base station; the infrared light beam angle ≤ the ultrasonic wave beam angle; the feedback information comprises a base station number, a timing duration, and a base station coordinate.

[0127] The functions and working principles of the above devices, apparatuses, modules, and units can refer to the corresponding explanations in Embodiment 2, and will not be described here.

[0128] Embodiment 6: Corresponding to Embodiment 3, another indoor positioning system of the light-synchronized ultrasonic wave single-pass ranging mobile device is provided, comprising a positioning device installed on each mobile device and a plurality of fixedly arranged positioning base stations; the positioning device comprises: The channel occupation application module is configured to broadcast a channel occupation application of the mobile device; the channel occupation application comprises a device number of the mobile device. The polling queue establishing module is configured to establish a polling queue according to the priority of the positioning task and / or the time sequence of the channel occupation application. The waiting time length obtaining module is configured to obtain a waiting time length according to the channel time length and the bit of the channel number of the mobile device in the polling queue. The positioning task executing module is configured to execute the positioning task and broadcast a positioning task starting time after the waiting time length ends. The running control module is configured to adjust the device number of the mobile device to the end of the polling queue after the positioning task is completed, and control the channel occupation application module to work. The positioning task executing module comprises: The infrared light emitter is configured to emit infrared light to each positioning base station. The ultrasonic wave emitter is configured to emit ultrasonic wave to each positioning base station. The numerical value calculating unit is configured to obtain a two-dimensional plane distance between the mobile device and each positioning base station corresponding to the received feedback information, and establish a plane distance set. The analysis unit is configured to determine whether a two-dimensional plane distance greater than or equal to a first threshold value can be filtered out from the plane distance set. The first coordinate obtaining unit is configured to, under the condition that a two-dimensional plane distance greater than or equal to the first threshold value can be filtered out from the plane distance set, take a base station coordinate of a positioning base station corresponding to any filtered two-dimensional plane distance as a positioning coordinate of the mobile device. The second coordinate obtaining unit is configured to, under the condition that a two-dimensional plane distance greater than or equal to the first threshold value cannot be filtered out from the plane distance set, obtain a positioning coordinate of the mobile device through three-edge solution. The positioning base station comprises: The timer is configured to start timing at the moment when the infrared light arrives and end timing at the moment when the ultrasonic wave arrives. The information sending module is configured to send feedback information to each mobile device located within a defined range; the defined range refers to a range defined by an infrared light beam angle below the positioning base station; the infrared light beam angle ≤ the ultrasonic wave beam angle; the feedback information comprises a base station number, a timing time length and a base station coordinate.

[0129] The functions and working principles of the above devices, equipment, modules and units can be referred to the corresponding explanations in Embodiment 3, and the description of the present embodiment will not be repeated.

[0130] It should be understood that the terms "system," "apparatus," "unit," and / or "module" as used herein are used generically to refer to different levels of aggregation of different components, elements, parts, sections, or assemblies. Other words, such as "include," "comprise," or "have," are used synonymously with "comprising" in the sense of including, but not limited to, as in the case of "comprising," the item listed after the "include," "comprise," or "have" is not the only item in a corresponding list of items.

[0131] As used in the specification and claims, unless otherwise specified, "a," "an," "the," and / or "at least one" are used generically and not as a limitation regarding the number of structures. In general, the term "or" as used herein means "and / or," unless otherwise indicated.

[0132] The above detailed description has been given to the present application, the purpose, technical solutions and beneficial effects of which are further described in detail. It should be understood that the above description is only a specific embodiment of the present application and does not limit the protection scope of the present application. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present application shall be included in the protection scope of the present application.

[0133] It should be noted that the structures, proportions, sizes, etc. shown in the drawings attached to the present specification are only used to illustrate the content disclosed in the specification, to enable those skilled in the art to understand and read, and are not used to limit the conditions that can be implemented by the present application. Therefore, any modification of the structure, change of the proportion relationship or adjustment of the size, which does not affect the effects that can be produced by the present application and the purposes that can be achieved, shall still fall within the scope of the technical content disclosed by the present application. At the same time, the terms such as "up", "down", "left", "right", "middle", etc. cited in the present specification are only for the convenience of clear description, and are not used to limit the scope of implementation of the present application. The change or adjustment of the relative relationship without substantial change of the technical content is also considered as the scope of implementation of the present application.

Claims

1. An indoor positioning method for mobile devices using optically synchronized ultrasonic one-way ranging, characterized in that, Execute S1 and S2 on each mobile device: S1: Determine whether this mobile device has obtained location permissions; S2: If location permissions have been obtained, execute the location task, and execute task A synchronously during the location task execution; When the location task is completed, execute tasks B and C in sequence, and return to S1; Task A includes: creating an application list and writing the application list into the permission allocation response; Task B includes: broadcasting the permission allocation response, clearing the permission status, and outputting the location coordinates; Task C includes: broadcasting a location permission request; if location permission is not obtained, broadcast a location permission request and return to S1; Performing a location task includes the following steps: The device transmits infrared light and ultrasonic waves to the positioning base station. The infrared light contains the device number of the mobile device, and the infrared beam angle is less than or equal to the ultrasonic beam angle. The positioning base station is used to start timing when the infrared light arrives and to end timing when the ultrasonic waves arrive, as well as to send feedback information to each mobile device within the wireless signal coverage area. The feedback information includes: the one-way flight time of the ultrasonic waves, the base station coordinates, and the device number. The one-way flight time of the ultrasonic waves = the timing end time - the timing start time. Determine if the device ID in each feedback message matches the device ID of this mobile device; if they do not match, discard the feedback message; if they match, retain the feedback message. Obtain the two-dimensional planar distance between this mobile device and the positioning base station corresponding to each feedback information, and establish a set of planar distances; Determine whether a two-dimensional plane distance ≥ the first threshold can be selected from the set of plane distances; if so, use the base station coordinates of the positioning base station corresponding to any selected two-dimensional plane distance as the positioning coordinates of this mobile device; if not, obtain the positioning coordinates of this mobile device through trilateration.

2. The indoor positioning method for mobile devices using optically synchronized ultrasonic one-way ranging according to claim 1, characterized in that, S1 includes: Continuously scan other mobile devices for location permission requests or permission allocation responses broadcast at a fixed frequency; If no location permission request or permission allocation response is detected after multiple consecutive scans, the permission status of this mobile device will be set to "location permission granted". If a permission allocation response is detected, read the request list in the permission allocation response; determine whether the location permission request of this mobile device is at the head of the request list; if yes, set the permission status of this mobile device to "location permission granted"; otherwise, set the permission status of this mobile device to "location permission denied".

3. The indoor positioning method for mobile devices using optically synchronized ultrasonic one-way ranging according to claim 1, characterized in that, Create an application list. Continuously collect location permission requests broadcast by other mobile devices; Sort all location permission requests collected in chronological order and create a request list.

4. An indoor positioning method for mobile devices using optically synchronized ultrasonic one-way ranging, characterized in that, Includes the following steps: S1: Number each mobile device according to the order in which they are started; S2: Divide the duration of one second on the timeline into multiple consecutive time slices of equal length, and number the time slices cyclically according to the number of mobile devices; S3: Send a control signal and the current time slice number to each mobile device; the control signal is used to control the mobile device to determine whether the number of the mobile device matches the number of the current time slice. If they match, broadcast a feedback signal and execute the positioning task. When the positioning task ends, broadcast a task end signal. If they do not match, enter a waiting state. S4: When a task completion signal is received or no feedback signal is received, jump to the next time slice and return to S3; when a mobile device is added or removed indoors, return to S1. Performing a location task includes the following steps: The device transmits infrared light and ultrasonic waves to the positioning base station. The infrared light contains the device number of the mobile device, and the infrared beam angle is less than or equal to the ultrasonic beam angle. The positioning base station is used to start timing when the infrared light arrives and to end timing when the ultrasonic waves arrive, as well as to send feedback information to each mobile device within the wireless signal coverage area. The feedback information includes: the one-way flight time of the ultrasonic waves, the base station coordinates, and the device number. The one-way flight time of the ultrasonic waves = the timing end time - the timing start time. Determine if the device ID in each feedback message matches the device ID of this mobile device; if they do not match, discard the feedback message; if they match, retain the feedback message. Obtain the two-dimensional planar distance between this mobile device and the positioning base station corresponding to each feedback information, and establish a set of planar distances; Determine whether a two-dimensional plane distance ≥ the first threshold can be selected from the set of plane distances; if so, use the base station coordinates of the positioning base station corresponding to any selected two-dimensional plane distance as the positioning coordinates of this mobile device; if not, obtain the positioning coordinates of this mobile device through trilateration.

5. The indoor positioning method for mobile devices using optically synchronized ultrasonic one-way ranging according to claim 4, characterized in that, Dividing each second into multiple consecutive time slices of equal length includes the following steps: S2.1: Obtain the one-way flight time of the ultrasonic wave based on the indoor floor height; S2.2: Obtain the sum of the one-way flight time, ultrasonic transmission delay, base station timing duration, base station data processing duration, base station information feedback duration, and positioning coordinate acquisition duration to obtain the total positioning task time; S2.3: Calculate the number of time slices based on the total time consumed by the positioning task and the expected positioning refresh rate; S2.4: If the number of time slices is less than the number of mobile devices, reduce the positioning refresh rate and return to S2.3; if the number of time slices is greater than or equal to the number of mobile devices, execute S2.

5. S2.5: Divide the unit time into equal time intervals according to the number of time slices to obtain multiple continuous time slices of equal length.

6. An indoor positioning method for mobile devices using optically synchronized ultrasonic one-way ranging, characterized in that, Perform the following steps on each mobile device: S1: Broadcasts a channel occupancy request for this mobile device; the channel occupancy request includes the device number of this mobile device; S2: Establish a polling queue based on the priority of the positioning task and / or the order of channel occupancy requests; S3: Obtain the waiting time based on the channel duration and the position of the mobile device's channel number in the polling queue; S4: After the waiting period ends, execute the location task and broadcast the location task start time. After the location task is completed, move the device number of this mobile device to the end of the polling queue and return to S1. Performing a location task includes the following steps: The device transmits infrared light and ultrasonic waves to the positioning base station. The infrared light contains the device number of the mobile device, and the infrared beam angle is less than or equal to the ultrasonic beam angle. The positioning base station is used to start timing when the infrared light arrives and to end timing when the ultrasonic waves arrive, as well as to send feedback information to each mobile device within the wireless signal coverage area. The feedback information includes: the one-way flight time of the ultrasonic waves, the base station coordinates, and the device number. The one-way flight time of the ultrasonic waves = the timing end time - the timing start time. Determine if the device ID in each feedback message matches the device ID of this mobile device; if they do not match, discard the feedback message; if they match, retain the feedback message. Obtain the two-dimensional planar distance between this mobile device and the positioning base station corresponding to each feedback information, and establish a set of planar distances; Determine whether a two-dimensional plane distance ≥ the first threshold can be selected from the set of plane distances; if so, use the base station coordinates of the positioning base station corresponding to any selected two-dimensional plane distance as the positioning coordinates of this mobile device; if not, obtain the positioning coordinates of this mobile device through trilateration.

7. The indoor positioning method for mobile devices using optically synchronized ultrasonic one-way ranging according to claim 6, characterized in that, S4 and earlier included: Continuously collect the location task start time broadcast by other mobile devices; Obtain the time deviation between the start time and waiting time of the location task; The remaining waiting time is adjusted based on the time deviation.

8. The indoor positioning method for mobile devices using optically synchronized ultrasonic one-way ranging according to any one of claims 1-7, characterized in that, Transmitting infrared light and ultrasonic waves to each positioning base station includes the following steps: Transmit infrared light to each positioning base station; After waiting for a preset fixed time, it transmits ultrasonic waves to each positioning base station.

9. The indoor positioning method for mobile devices using optically synchronized ultrasonic one-way ranging according to any one of claims 1-7, characterized in that, Obtaining a two-dimensional plane distance includes the following steps: The corrected timing duration is obtained by subtracting the inherent delay of the infrared transmitter, the inherent delay of the ultrasonic transmitter, the reaction time of the infrared receiver module, the reaction time of the ultrasonic receiver module, and the correction parameters of the one-way flight time from the timing duration. The actual speed of the ultrasound is obtained by correcting the speed of the ultrasound using Cramer's empirical formula. The three-dimensional spatial distance between the mobile device and the positioning base station is calculated using the corrected timing duration and the actual speed of the ultrasonic wave; Obtain the elevation difference between the positioning base station and the mobile device; Based on the elevation difference and the Pythagorean theorem, the three-dimensional spatial distance is converted into a two-dimensional planar distance.

10. The indoor positioning method for mobile devices using optically synchronized ultrasonic one-way ranging according to any one of claims 1-7, characterized in that, The positioning coordinates are obtained through trilateration, including the following steps: Enumerate all combinations of positioning base stations that meet the preset conditions; the preset conditions are: the area of ​​the triangle formed by the three positioning base stations is greater than or equal to the third threshold. Calculate the area of ​​the triangle formed by each combination of positioning base stations, and select the combination of positioning base stations with the largest triangle area as the optimal combination; The location coordinates of the mobile device are obtained by performing trilateration calculation using the base station coordinates of the three optimally combined positioning base stations.

11. An indoor positioning system for mobile devices using optically synchronized ultrasonic one-way ranging, characterized in that, include: Positioning devices installed on each mobile device and multiple fixed positioning base stations; The positioning device includes: The analysis module is used to determine whether the mobile device has obtained location permissions; The first task execution module is used to perform location tasks provided that the mobile device has obtained location permissions. The second task execution module is used to execute task A synchronously during the location task execution; task A includes: establishing an application list and writing the application list into the permission allocation response; The third task execution module is used to execute task B and task C sequentially when the positioning task ends. Task B includes: broadcasting permission allocation response, clearing permission status and outputting positioning coordinates. Task C includes: broadcasting positioning permission request; if positioning permission is not obtained, broadcasting positioning permission request. The fourth task execution module is used to broadcast a location permission request when the mobile device has not obtained location permission. The operation control module is used to control the analysis module to work after completing tasks B and C or after broadcasting a location permission request when the mobile device has not obtained location permission. The first task execution module includes: An infrared light emitter is used to transmit infrared light to a positioning base station; the infrared light contains the device number of this mobile device. An ultrasonic transmitter is used to transmit ultrasonic waves to a positioning base station; the infrared beam angle is ≤ the ultrasonic beam angle. The information processing unit is used to determine whether the device number in each feedback message matches the device number of the mobile device; if they do not match, the feedback message is discarded; if they match, the feedback message is retained. The numerical calculation unit is used to obtain the two-dimensional planar distance between this mobile device and the positioning base station corresponding to each feedback information, and to establish a set of planar distances; The analysis unit is used to determine whether two-dimensional planar distances greater than or equal to a first threshold can be selected from the set of planar distances. The first coordinate acquisition unit is used to take the base station coordinates of the positioning base station corresponding to any selected two-dimensional plane distance as the positioning coordinates of the mobile device, provided that a two-dimensional plane distance greater than or equal to a first threshold can be selected from the set of plane distances. The second coordinate acquisition unit is used to obtain the positioning coordinates of the mobile device by trilateration when a two-dimensional plane distance greater than or equal to the first threshold cannot be filtered out from the plane distance set. Positioning base stations include: A timer, used to start timing when infrared light arrives and stop timing when ultrasonic waves arrive; The information transmission module is used to send feedback information to each mobile device within the wireless signal coverage area; the feedback information includes: the one-way flight time of the ultrasonic wave, the base station coordinates, and the device number; the one-way flight time of the ultrasonic wave = the end time of timing - the start time of timing.

12. An indoor positioning system for mobile devices using optically synchronized ultrasonic one-way ranging, characterized in that, include: The controller, the positioning device installed on each mobile device, and multiple fixed positioning base stations; The controller includes: The first numbering module is used to number each mobile device according to the order in which the devices are started. The second numbering module is used to divide the duration of one second into multiple consecutive time slices of equal length on the time axis, and to cyclically number the time slices according to the number of mobile devices. The signal transmission module is used to send control signals and the current time slice number to each mobile device. The control signal is used to control the mobile device to determine whether the number of the mobile device matches the number of the current time slice. If they match, the device broadcasts a feedback signal and executes the positioning task. When the positioning task ends, the device broadcasts a task end signal. If they do not match, the device enters a waiting state. The operation control module is used to jump to the next time slice when a task end signal is received or no feedback signal is received, and to control the signal sending module to work. When new or fewer mobile devices are added indoors, the module controls the first number setting module to work. The positioning device includes: An infrared light emitter is used to transmit infrared light to a positioning base station; the infrared light contains the device number of this mobile device. An ultrasonic transmitter is used to transmit ultrasonic waves to a positioning base station; the infrared beam angle is ≤ the ultrasonic beam angle. The information processing unit is used to determine whether the device number in each feedback message matches the device number of the mobile device; if they do not match, the feedback message is discarded; if they match, the feedback message is retained. The numerical calculation unit is used to obtain the two-dimensional planar distance between this mobile device and the positioning base station corresponding to each feedback information, and to establish a set of planar distances; The analysis unit is used to determine whether two-dimensional planar distances greater than or equal to a first threshold can be selected from the set of planar distances. The first coordinate acquisition unit is used to take the base station coordinates of the positioning base station corresponding to any selected two-dimensional plane distance as the positioning coordinates of the mobile device, provided that a two-dimensional plane distance greater than or equal to a first threshold can be selected from the set of plane distances. The second coordinate acquisition unit is used to obtain the positioning coordinates of the mobile device by trilateration when a two-dimensional plane distance greater than or equal to the first threshold cannot be filtered out from the plane distance set. Positioning base stations include: A timer, used to start timing when infrared light arrives and stop timing when ultrasonic waves arrive; The information transmission module is used to send feedback information to each mobile device within the wireless signal coverage area; the feedback information includes: the one-way flight time of the ultrasonic wave, the base station coordinates, and the device number; the one-way flight time of the ultrasonic wave = the end time of timing - the start time of timing.

13. An indoor positioning system for mobile devices using optically synchronized ultrasonic one-way ranging, characterized in that, include: Positioning devices installed on each mobile device and multiple fixed positioning base stations; The positioning device includes: The channel occupancy request module is used to broadcast a channel occupancy request for this mobile device; the channel occupancy request includes the device number of this mobile device; The polling queue establishment module is used to establish polling queues according to the priority of positioning tasks and / or the order of channel occupancy requests. The waiting time acquisition module is used to acquire the waiting time based on the channel duration and the position of the channel number of this mobile device in the polling queue; The location task execution module is used to execute the location task after the waiting period has ended and broadcast the location task start time. The operation control module is used to adjust the device number of this mobile device to the end of the polling queue after the positioning task is completed, and to control the channel occupancy application module to work. The location task execution module includes: An infrared light emitter is used to transmit infrared light to a positioning base station; the infrared light contains the device number of this mobile device. An ultrasonic transmitter is used to transmit ultrasonic waves to a positioning base station; the infrared beam angle is ≤ the ultrasonic beam angle. The information processing unit is used to determine whether the device number in each feedback message matches the device number of the mobile device; if they do not match, the feedback message is discarded; if they match, the feedback message is retained. The numerical calculation unit is used to obtain the two-dimensional planar distance between this mobile device and the positioning base station corresponding to each feedback information, and to establish a set of planar distances; The analysis unit is used to determine whether two-dimensional planar distances greater than or equal to a first threshold can be selected from the set of planar distances. The first coordinate acquisition unit is used to take the base station coordinates of the positioning base station corresponding to any selected two-dimensional plane distance as the positioning coordinates of the mobile device, provided that a two-dimensional plane distance greater than or equal to a first threshold can be selected from the set of plane distances. The second coordinate acquisition unit is used to obtain the positioning coordinates of the mobile device by trilateration when a two-dimensional plane distance greater than or equal to the first threshold cannot be filtered out from the plane distance set. Positioning base stations include: A timer, used to start timing when infrared light arrives and stop timing when ultrasonic waves arrive; The information transmission module is used to send feedback information to each mobile device within the wireless signal coverage area; the feedback information includes: the one-way flight time of the ultrasonic wave, the base station coordinates, and the device number; the one-way flight time of the ultrasonic wave = the end time of timing - the start time of timing.

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