Indoor planar map construction method and system based on smartphone sound wave ranging

Abstract

The application provides an indoor planar graph construction method and system based on a smartphone sound wave ranging, belongs to the technical field of indoor design, emits a sound wave signal, receives a echo signal by two microphones of the smartphone, calculates the distance between the wall and the smartphone, obtains inertia data of the smartphone to track a moving track and identify an indoor connection area, combines the distance between the wall and the smartphone, a user track and the indoor connection area, and constructs an indoor planar graph by a map refinement algorithm. The application can complete the construction of the indoor planar graph based on the smartphone, reduces the construction cost of the indoor planar graph, improves the efficiency, does not need to shoot an indoor environment, is not affected by environmental illumination conditions, avoids the indoor privacy leakage of the user, adopts unilateral ranging, can still effectively complete the construction of the planar graph when the Batmapper cannot be normally used in a wide indoor environment, generates a more complete planar graph in a non-discrete point form, and is more in line with the real indoor structure.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of interior design, and particularly relates to an indoor planar graph construction method and system based on acoustic ranging of a smart phone. BACKGROUND

[0002] Indoor positioning services have brought great convenience to our modern life, especially in large hospitals, multi-story shopping malls and underground parking lots. However, its deployment has not yet been popularized, and one of the main obstacles is the lack of floor plans for indoor positioning and navigation.

[0003] Existing special-purpose mapping systems rely on mobile robots equipped with cameras and other high-precision sensors to construct accurate indoor maps. However, the cost of such systems is always high and has not been popularized on a large scale.

[0004] Currently, the construction of traditional indoor floor plans is mainly achieved by combining images and inertial sensors. For example, Jigsaw obtains the spatial relationship between adjacent landmark objects from images taken by users and inertial sensor data, and combines the user's trajectory and the position of the captured image to generate a complete floor plan. Plansketcher uses deep learning technology to extract new comprehensive features to identify different landmark points. Then, based on sensor data, depth data and images, an indoor floor plan is constructed. IndoorCrowd2D uses image information and sensory data in crowd-sourced data to recover the structure of a building. MapGENIE uses a grammar to represent the structural information of a building, which is better than simple trajectory mapping.

[0005] As for the method of using a smart phone combined with an augmented reality / virtual reality application program to construct a 3D point cloud for indoor objects using computer vision technology, due to the influence of environmental light conditions on images, the constructed structure is not accurate, and there is a risk of user privacy leakage. Batmapper is a system that uses bilateral sound signals to construct an indoor map (Zhou B, Elbadry M, Gao R, et al. BatMapper: Acoustic sensing based indoor floor plan construction using smartphones [C] / / Proceedings of the 15th Annual International Conference on Mobile Systems, Applications, and Services. 2017: 42-55.), but the wall coordinate point information obtained thereby cannot represent the real wall structure, and cannot be directly applied to indoor positioning and navigation. SUMMARY

[0006] The present application aims to provide a smartphone acoustic ranging-based indoor planar map construction method and system which can be directly applied to indoor navigation and positioning and is not affected by lighting conditions and has high privacy, so as to solve at least one technical problem in the background art.

[0007] To achieve the above-mentioned purpose, the present application adopts the following technical solutions:

[0008] In one aspect, the present application provides a smartphone acoustic ranging-based indoor planar map construction method, comprising:

[0009] The loudspeaker of the smartphone is used to emit an acoustic signal;

[0010] Two microphones of the smartphone are used to receive echo signals reflected by indoor walls;

[0011] Based on the two received echo signals, the distance between the wall and the smartphone is calculated;

[0012] Inertial data of the smartphone are obtained to track the user trajectory of the smartphone and identify indoor connection areas;

[0013] The distance between the wall and the smartphone, the user trajectory and the indoor connection area are combined, and an indoor planar map is constructed through a map refinement algorithm.

[0014] Preferably, a frequency-modulated continuous wave is used to generate the acoustic signal, and the generated acoustic signal has a duration of 3ms and a frequency range of 8KHz-16KHz.

[0015] Preferably, the echo signal and the emitted acoustic signal have consistent waveforms and have a time delay Δt, and the calculation formula of the time delay Δt is:

[0016]

[0017] Wherein, f min is the minimum frequency of the emitted signal, f max is the maximum frequency of the emitted signal, and T is the duration of the emitted signal.

[0018] Preferably, when the user holds the smartphone and walks horizontally, the difference in propagation distance of the signals received by the two microphones of the smartphone is the length l of the smartphone, and the distance between the wall and the smartphone is represented as:

[0019]

[0020] Wherein, v sound is the speed of sound propagation.

[0021] Preferably, dead reckoning is used to track the pace, stride and direction of a walking user, self-defined according to outdoor trajectories using GPS; stride is calculated by detecting the peak and valley of vertical acceleration; the moving direction is calculated using the gamervAPI of a smartphone.

[0022] Preferably, the wall segments are positioned as scattered points on the map by the user trajectory and the distance between the wall and the smartphone, and the remaining scattered points are fitted as line segments after removing the detected doors and windows, i.e. f(x) = kx + b; where k is the gradient and b is the offset;

[0023] In order to minimize the error between the wall segments and the scattered points, the objective function is:

[0024]

[0025] where e represents the sum of errors, n represents the number of points on the wall, (x i ,y i ) is the coordinate of the ith point obtained by distance measurement;

[0026] In order to minimize e, the partial derivatives of k and b are calculated respectively:

[0027]

[0028]

[0029] Therefore,

[0030]

[0031]

[0032] where is the average value, and the final reconstruction plan is optimized using wall segments, doors / windows and corners.

[0033] In a second aspect, the present application provides an indoor planar graph construction system based on smartphone acoustic ranging, comprising:

[0034] a transmitting module for transmitting acoustic signals using the speaker of the smartphone;

[0035] a receiving module for receiving echo signals reflected by indoor walls using two microphones of the smartphone;

[0036] a calculation module for calculating the distance between the wall and the smartphone based on the two received echo signals;

[0037] an acquisition module for acquiring inertial data of the smartphone to track the user trajectory of the smartphone and identify indoor connection areas;

[0038] An optimization module is configured to combine the distance between the wall and the smart phone, the user trajectory and the indoor connection area, and construct an indoor plan by a map refinement algorithm.

[0039] In a third aspect, the present application provides a non-transitory computer readable storage medium for storing computer instructions, which, when executed by a processor, implement the indoor plan construction method based on the smart phone sound wave ranging as described above.

[0040] In a fourth aspect, the present application provides a computer program product comprising a computer program which, when running on one or more processors, is configured to implement the indoor plan construction method based on the smart phone sound wave ranging as described above.

[0041] In a fifth aspect, the present application provides an electronic device comprising a processor, a memory and a computer program; wherein the processor is connected to the memory, and the computer program is stored in the memory; when the electronic device is running, the processor executes the computer program stored in the memory, so as to make the electronic device execute the instructions for implementing the indoor plan construction method based on the smart phone sound wave ranging as described above.

[0042] The present application has the advantages that the indoor plan construction can be completed based on the smart phone, the indoor plan construction cost is reduced, and the efficiency is improved; the indoor environment does not need to be photographed, and is not affected by the environmental light conditions, thereby avoiding the indoor privacy leakage of the user; the single-side ranging is adopted, and when the Batmapper cannot be normally used in the wide indoor environment, the plan construction can still be effectively completed, a more complete plan is generated, and the plan is in the form of a discrete point, which is more consistent with the real indoor structure.

[0043] The advantages of the additional aspects of the present application will be more apparent from the following description part or be understood through the practice of the present application. BRIEF DESCRIPTION OF DRAWINGS

[0044] In order to more clearly illustrate the technical solutions of the embodiments of the present application, the following will briefly introduce the drawings needed to be used in the embodiment description. Obviously, the drawings in the following description are only some embodiments of the present application, and other drawings can also be obtained by those skilled in the art without creative labor.

[0045] Figure 1 The indoor plan construction flowchart described in the embodiments of the present application.

[0046] Figure 2 The schematic diagram of calculating the distance by emitting and receiving the sound wave signal described in the embodiments of the present application.

[0047] Figure 3 This is a schematic diagram illustrating unilateral distance measurement using a smartphone as described in an embodiment of the present invention.

[0048] Figure 4 This is a schematic diagram of the wall coordinate points obtained according to an embodiment of the present invention.

[0049] Figure 5 For the corresponding Figure 4 The optimized complete floor plan of the walls.

[0050] Figure 6 This is a schematic diagram of the acceleration change at the staircase as described in an embodiment of the present invention.

[0051] Figure 7 This is a schematic diagram illustrating the change in acceleration of an elevator during ascent, as described in an embodiment of the present invention.

[0052] Figure 8 This is a schematic diagram illustrating the change in acceleration during elevator descent as described in an embodiment of the present invention. Detailed Implementation

[0053] Embodiments of the present invention are described in detail below, examples of which are shown in the accompanying drawings, wherein the same or similar reference numerals denote the same or similar elements or elements having the same or similar functions throughout. The embodiments described below with reference to the accompanying drawings are exemplary and are only used to explain the present invention, and should not be construed as limiting the present invention.

[0054] It will be understood by those skilled in the art that, unless otherwise defined, all terms used herein (including technical and scientific terms) have the same meaning as commonly understood by one of ordinary skill in the art to which this invention pertains.

[0055] It should also be understood that terms such as those defined in general dictionaries should be understood to have meanings consistent with their meanings in the context of the prior art, and should not be interpreted in an idealized or overly formal sense unless defined as here.

[0056] Those skilled in the art will understand that, unless specifically stated otherwise, the singular forms “a,” “an,” “the,” and “the” used herein may also include the plural forms. It should be further understood that the term “comprising” as used in this specification means the presence of the stated features, integers, steps, operations, elements, and / or components, but does not exclude the presence or addition of one or more other features, integers, steps, operations, elements, and / or groups thereof.

[0057] In the description of the present specification, the description of the terms "one embodiment", "some embodiments", "an example", "a specific example", or "some examples" and the like means that the specific features, structures, materials or characteristics described in connection with the embodiment or example are included in at least one embodiment or example of the present application. Moreover, the specific features, structures, materials or characteristics described can be combined in any appropriate manner in any one or more embodiments or examples. In addition, the person skilled in the art can combine and combine the different embodiments or examples described in the specification and the features of the different embodiments or examples without contradiction.

[0058] In order to facilitate the understanding of the present application, the present application will be further explained and described in specific embodiments in conjunction with the accompanying drawings, and the specific embodiments do not constitute a limitation on the embodiments of the present application.

[0059] The person skilled in the art should understand that the drawings are only schematic diagrams of the embodiments, and the components in the drawings are not necessarily necessary for the implementation of the present application.

[0060] Embodiment 1

[0061] Embodiment 1 provides an indoor planar graph construction system based on smartphone sound wave ranging, which comprises:

[0062] The transmitting module is used to transmit the sound wave signal by the loudspeaker of the smartphone;

[0063] The receiving module is used to receive the echo signal reflected by the indoor wall by the two microphones of the smartphone;

[0064] The computing module is used to calculate the distance between the wall and the smartphone based on the two received echo signals;

[0065] The acquisition module is used to acquire the inertial data of the smartphone to track the user trajectory of the smartphone and identify the indoor connection area;

[0066] The optimization module is used to combine the distance between the wall and the smartphone, the user trajectory and the indoor connection area to construct the indoor planar graph by the map refinement algorithm.

[0067] In embodiment 1, the above system is used to realize an indoor planar graph construction method based on smartphone sound wave ranging, which comprises:

[0068] The transmitting module is used to transmit the sound wave signal by the loudspeaker of the smartphone;

[0069] The receiving module is used to receive the echo signal reflected by the indoor wall by the two microphones of the smartphone;

[0070] calculating the distance between the wall and the smartphone based on the received two echo signals using a calculation module;

[0071] acquiring the inertial data of the smartphone using an acquisition module to track the user trajectory of the smartphone and identify the indoor connection area;

[0072] combining the distance between the wall and the smartphone, the user trajectory and the indoor connection area using an optimization module, and constructing the indoor floor plan through a map refinement algorithm.

[0073] wherein a frequency-modulated continuous wave is used to generate the sound wave signal, and the generated sound wave signal has a duration of 3 ms and a frequency range of 8 KHz-16 KHz.

[0074] The echo signal and the transmitted sound wave signal have consistent waveforms and a time delay Δt, and the calculation formula of the time delay Δt is:

[0075]

[0076] wherein f min is the minimum frequency of the transmitted signal, f max is the maximum frequency of the transmitted signal, and T is the duration of the transmitted signal.

[0077] When the user holds the smartphone and walks horizontally, the difference in propagation distance of the signals received by the two microphones of the smartphone is the length l of the smartphone, and the distance between the wall and the smartphone is represented as:

[0078]

[0079] wherein v sound is the sound propagation speed.

[0080] The step length, step size and direction of the walking user are tracked using dead reckoning, and the outdoor trajectory is customized using GPS; the step length is calculated by detecting the peak and valley values of the vertical acceleration; and the moving direction is calculated using the gamerv API of the smartphone.

[0081] By the user trajectory and the distance between the wall and the smartphone, the wall segments are positioned as scattered points on the map, and after removing the detected doors and windows, the remaining scattered points are fitted as line segments, i.e. f(x) = kx + b; wherein k is the gradient and b is the offset;

[0082] In order to minimize the error between the wall segments and the scattered points, the objective function is:

[0083]

[0084] wherein e represents the sum of errors, n represents the number of points on the wall, (x i , yi ) is the coordinate of the ith point obtained by distance measurement;

[0085] To minimize e, the partial derivatives of k and b are calculated, respectively:

[0086]

[0087]

[0088] Therefore,

[0089]

[0090]

[0091] where, is the average value, and finally the reconstructed floor plan is optimized using wall segments, doors / windows, and corners.

[0092] Example 2

[0093] In this embodiment 2, an indoor floor plan construction method based on a smartphone combined with sound wave ranging is provided. As shown in Figure 1 , the method uses acoustic signals and inertial data as input. Frequency-modulated continuous wave (FMCW) is used as the output signal of the loudspeaker, two microphones (top / bottom) are used to receive the echo signal reflected by the side wall, and the distance between the wall and the smartphone is calculated. In addition, inertial data is collected from the smartphone to track the user and identify connected areas (such as stairs and elevators). Finally, distance measurement, trajectory and connected areas are fused, and a multi-layer indoor floor plan is constructed and refined through a map refinement algorithm.

[0094] The method of this embodiment 2 uses one-sided ranging. In the sound signal design part, the frequency of the sound signal should balance the physical ability of the smartphone and the background noise. The sound frequency of the smartphone is usually between 110Hz and 20KHz, while the frequency of human voice is always less than 1KHz. Therefore, we generate a sound signal with a duration of 3ms and a frequency range of 8KHz to 16KHz. We use frequency-modulated continuous wave (FMCW) to generate the signal (solid line in Figure 2 ).

[0095] The distance to the wall is calculated when the emitted sound signal meets the wall, its echo signal is reflected back and received by the microphone of the smartphone. As shown in Figure 2 , the received signal and the transmitted signal have consistent waveforms with a time delay At. The calculation formula of the time delay At is:

[0096]

[0097] where fmin is the minimum frequency of the transmitted signal, f max is the maximum frequency of the transmitted signal, T is the duration of the transmitted signal.

[0098] As Figure 3 shown, during horizontal walking when the user holds the smartphone, path 1 represents the propagation path of the signal received by the top microphone, and path 2 represents the transmission path of the signal received by the bottom microphone. The difference in propagation distance of the signals received by the two microphones is the length of the smartphone, / . Therefore, when the difference in distance from the side wall measured by the two microphones is close to 2 / , the received signal is likely to be an echo reflected from the side wall. The distance between the wall and the smartphone is represented as:

[0099]

[0100] where v sound is the speed of sound propagation.

[0101] In this embodiment 2, in the map construction and refinement design part, first the user's trajectory tracking (i.e. the moving trajectory of the smartphone) is performed. Dead reckoning is used to track the user's pace, step length and direction. The normal pace of an adult is about 60 cm, which is used as the default value, and can be customized according to the outdoor trajectory using GPS. Then the step length is calculated by detecting the peak and valley values of the vertical acceleration, and their difference threshold is set to 3 m / s 2 , and the duration threshold between the two steps is set to 400 ms to avoid errors caused by arm vibration. In order to eliminate the drift of the gyroscope and the noise of the magnetometer, we use the gamerv API of the smartphone to calculate the direction, which integrates the accelerometer, gyroscope and magnetometer, and has robustness.

[0102] In this embodiment 2, door and window detection is also performed before map optimization. The existence of doors and windows is determined by detecting the change in distance between the smartphone and the side wall. When the change exceeds the threshold (20 cm), the point is considered as a door / window. When the door / window length is too short, these points are deleted as outliers.

[0103] The map refinement process is as follows:

[0104] By combining the user's trajectory and distance measurement, the wall segments are positioned as scattered points on the map. These scattered points not only contain outliers with extreme errors, but also such a plan does not match the actual map. Usually most walls are composed of line segments, and their intersection points can be identified by the turning events of the walking user. After removing the detected doors and windows, the remaining points are fitted as line segments, i.e.

[0105] f(x) = kx + b

[0106] where k is the gradient and b is the offset. To minimize the error between the wall segments and the scatter points, the objective function is constructed as:

[0107]

[0108] where e represents the sum of errors, n represents the number of points on the wall, (x i ,y i ) is the coordinate of the ith point obtained by distance measurement. To minimize e, the partial derivatives of k and b are calculated respectively:

[0109]

[0110]

[0111] Therefore

[0112]

[0113]

[0114] where is the average value. Finally, the reconstructed floor plan is optimized using the wall segments, doors / windows and corners, i.e. the position coordinate points of Figure 4 are optimized to the complete floor plan of Figure 5 .

[0115] Finally, the connecting region detection is performed. Since modern buildings are always multi-story with different types of connecting regions, the stairs and elevators are automatically identified to associate each floor of the floor plan.

[0116] When climbing stairs, the acceleration always has a large change. To eliminate the influence of the smartphone posture, the amplitude of the three-axis acceleration on the smartphone is calculated, as shown in Figure 6 . Next, the sliding window is used to dynamically detect the peak and valley along the acceleration sequence. To avoid errors caused by handshaking, the minimum time interval between the peak and the valley is set to 400ms. When the elevator starts or stops, the acceleration of the smartphone along the gravity direction will change accordingly, and it will remain stable when the elevator moves at a constant speed. As shown in Figure 7 、 Figure 8 , when the elevator is descending, the vertical acceleration first decreases and then increases, and vice versa. A 3-second sliding window is adopted to detect its rising / falling interval, and verify whether the two periods are within a reasonable period (30 seconds).

[0117] Example 3

[0118] Embodiment 3 of the present application provides a non-transitory computer readable storage medium for storing computer instructions, which, when executed by a processor, implement an indoor planar graph construction method based on sound wave ranging of a smart phone, the method comprising:

[0119] a speaker of the smart phone is used to emit a sound wave signal;

[0120] two microphones of the smart phone are used to receive echo signals reflected by indoor walls;

[0121] based on the two received echo signals, a distance between the walls and the smart phone is calculated;

[0122] inertial data of the smart phone is obtained to track a user trajectory of the smart phone and identify an indoor connection area;

[0123] the distance between the walls and the smart phone, the user trajectory and the indoor connection area are combined, and an indoor planar graph is constructed through a map refinement algorithm.

[0124] Embodiment 4

[0125] Embodiment 4 of the present application provides a computer program (product) comprising a computer program which, when running on one or more processors, is used to implement an indoor planar graph construction method based on sound wave ranging of a smart phone, the method comprising:

[0126] a speaker of the smart phone is used to emit a sound wave signal;

[0127] two microphones of the smart phone are used to receive echo signals reflected by indoor walls;

[0128] based on the two received echo signals, a distance between the walls and the smart phone is calculated;

[0129] inertial data of the smart phone is obtained to track a user trajectory of the smart phone and identify an indoor connection area;

[0130] the distance between the walls and the smart phone, the user trajectory and the indoor connection area are combined, and an indoor planar graph is constructed through a map refinement algorithm.

[0131] Embodiment 5

[0132] Embodiment 5 of the present application provides an electronic device comprising a processor, a memory and a computer program; wherein the processor is connected with the memory, and the computer program is stored in the memory; when the electronic device is running, the processor executes the computer program stored in the memory to make the electronic device execute instructions for implementing an indoor planar graph construction method based on sound wave ranging of a smart phone, the method comprising:

[0133] emit sound wave signals using a speaker of the smartphone;

[0134] receive echo signals reflected by indoor walls using two microphones of the smartphone;

[0135] calculate the distance between the walls and the smartphone based on the received two echo signals;

[0136] obtain inertial data of the smartphone to track the user trajectory of the smartphone and identify indoor connection areas;

[0137] combine the distance between the walls and the smartphone, the user trajectory, and the indoor connection areas, and construct an indoor floor plan through a map refinement algorithm.

[0138] In summary, the indoor floor plan construction method and system based on the smartphone sound wave ranging according to the embodiments of the present application is single-sided acoustic ranging. The single-sided acoustic ranging ensures low limitations and is effective in corridors and wide indoor environments. The acoustic ranging ensures that it is not affected by light conditions and has high privacy. The map construction and refinement method converts discrete points representing wall structures into wall segments that can represent real wall structures, eliminates outliers, and completes wall information to obtain a more complete floor plan. Through the detection and labeling of different floor connection areas (such as stairs and elevators), the floor plan can represent a multi-floor indoor structure. Compared with a dedicated map system, the present application only needs a smartphone to complete the construction of an indoor floor plan, which has a lower cost. Compared with computer vision technology for constructing an indoor map, the present application does not need to take pictures of the indoor environment, is not affected by environmental light conditions, and has high privacy. Compared with Batmapper, the present application uses single-sided ranging, which is still effective when Batmapper cannot be normally used in a wide indoor environment. At the same time, the present application generates a more complete floor plan rather than discrete points, which is more consistent with the real indoor structure.

[0139] Those skilled in the art will appreciate that embodiments of the present application can be provided as methods, systems, or computer program products. Accordingly, the present application can be embodied in the form of an entirely hardware embodiment, an entirely software embodiment, or an embodiment combining software and hardware aspects. Furthermore, the present application can be embodied in the form of a computer program product embodied on one or more computer-usable storage media (including, but not limited to, disk memory, CD-ROMs, optical memory, etc.) having computer usable program code embodied thereon.

[0140] The computer program instructions can also be loaded onto a computer or other programmable data processing apparatus to cause a series of operational steps to be performed on the computer or other programmable apparatus to produce a computer-implemented process such that the instructions which execute on the computer or other programmable apparatus provide steps for implementing the functions specified in the flowchart or flows and / or block diagram block or blocks. Figure 1 one or more flow or flows and / or block or blocks. Figure 1 one or more flow or flows and / or block or blocks.

[0141] These computer program instructions can also be stored in a computer-readable memory that can direct a computer or other programmable data processing apparatus to function in a particular manner, such that the instructions stored in the computer-readable memory produce an article of manufacture including instructions which implement the function specified in the flowchart or flows and / or block diagram block or blocks. Figure 1 one or more flow or flows and / or block or blocks. Figure 1 one or more flow or flows and / or block or blocks.

[0142] The computer program instructions can also be loaded onto a computer or other programmable data processing apparatus to cause a series of operational steps to be performed on the computer or other programmable apparatus to produce a computer-implemented process such that the instructions which execute on the computer or other programmable apparatus provide steps for implementing the functions specified in the flowchart or flows and / or block diagram block or blocks. Figure 1 one or more flow or flows and / or block or blocks. Figure 1 one or more flow or flows and / or block or blocks.

[0143] The above description is only a specific implementation of the present application, and is not intended to limit the protection scope of the present application. It should be understood by those skilled in the art that various modifications or changes can be made to the disclosed technical solutions without departing from the spirit and scope of the present application.

Claims

1. A method for constructing an indoor floor plan based on smartphone acoustic ranging, characterized in that, include: The smartphone's speaker emits sound wave signals; Two microphones from a smartphone are used to receive echo signals reflected from an indoor wall; the echo signals have the same waveform as the transmitted sound waves and have a time delay Δt. The formula for calculating the time delay Δt is: Among them, f min It is the minimum frequency of the transmitted signal, f. max is the maximum frequency of the transmitted signal, and T is the duration of the transmitted signal; The distance between the wall and the smartphone is calculated based on the two received echo signals. Acquire inertial data from the smartphone to track the user's trajectory and identify indoor connectivity areas; during horizontal walking while holding the smartphone, the difference in propagation distance between the signals received by the two microphones on the smartphone is the length *l* of the smartphone, and the distance between the wall and the smartphone is expressed as: Among them, v sound It is the speed of sound propagation; Dead reckoning is used to track the stride length, direction, and direction of walking users, and GPS is used to customize the data based on outdoor tracks; stride length is calculated by detecting the peak and trough values ​​of vertical acceleration; and the direction of movement is calculated using the smartphone's Gamerv API. By combining the distance between the wall and the smartphone, user trajectory, and indoor connection area, an indoor floor plan is constructed using a map refinement algorithm. Specifically, the wall segments are located as scattered points on the map based on the user trajectory and the distance between the wall and the smartphone. After removing the detected doors and windows, the remaining scattered points are fitted as line segments, i.e., f(x) = kx + b, where k is the gradient and b is the offset. To minimize the error between the wall segment and the scattering point, the objective function is: Where e represents the sum of errors, n represents the number of points on the wall, (x i ,y i The coordinates of the i-th point are obtained through distance measurement. To minimize e, calculate the partial derivatives of k and b respectively: therefore, in, It is an average value, and the final reconstruction plan is optimized using wall segments, doors / windows, and corners.

2. The method for constructing indoor floor plans based on smartphone acoustic ranging according to claim 1, characterized in that, The sound wave signal is generated using frequency-modulated continuous wave, with a duration of 3ms and a frequency range of 8kHz to 16kHz.

3. An indoor floor plan construction system based on smartphone acoustic ranging, characterized in that, include: A transmitting module for emitting sound wave signals using a smartphone's speaker; The receiving module is used to receive echo signals reflected from indoor walls using two microphones from a smartphone; the echo signal has the same waveform as the transmitted sound wave signal and has a time delay Δt, which is calculated using the following formula: Among them, f min It is the minimum frequency of the transmitted signal, f. max is the maximum frequency of the transmitted signal, and T is the duration of the transmitted signal; The calculation module is used to calculate the distance between the wall and the smartphone based on the two received echo signals; The acquisition module is used to acquire inertial data from the smartphone to track the user's trajectory and identify indoor connectivity areas. When the user holds the smartphone and walks horizontally, the difference in propagation distance between the signals received by the two microphones on the smartphone is equal to the length *l* of the smartphone. The distance between the wall and the smartphone is expressed as: Among them, v sound It is the speed of sound propagation; Dead reckoning is used to track the stride length, direction, and direction of walking users, and GPS is used to customize the data based on outdoor tracks; stride length is calculated by detecting the peak and trough values ​​of vertical acceleration; and the direction of movement is calculated using the smartphone's Gamerv API. The optimization module is used to construct an indoor floor plan by combining the distance between the wall and the smartphone, the user's trajectory, and the indoor connection area through a map refinement algorithm. Specifically, the wall segments are located as scattered points on the map by using the user's trajectory and the distance between the wall and the smartphone. After removing the detected doors and windows, the remaining scattered points are fitted as line segments, i.e., f(x) = kx + b; where k is the gradient and b is the offset. To minimize the error between the wall segment and the scattering point, the objective function is: Where e represents the sum of errors, n represents the number of points on the wall, (x i ,y i The coordinates of the i-th point are obtained through distance measurement. To minimize e, calculate the partial derivatives of k and b respectively: therefore, in, It is an average value, and the final reconstruction plan is optimized using wall segments, doors / windows, and corners.

4. A non-transitory computer-readable storage medium, characterized in that, The non-transitory computer-readable storage medium is used to store computer instructions, which, when executed by a processor, implement the indoor floor plan construction method based on smartphone acoustic ranging as described in claim 1 or 2.

5. A computer program product, characterized in that, Includes a computer program, which, when run on one or more processors, is used to implement the method for constructing an indoor floor plan based on smartphone acoustic ranging as described in claim 1 or 2.

6. An electronic device, characterized in that, include: The device includes a processor, a memory, and a computer program; wherein the processor is connected to the memory, and the computer program is stored in the memory. When the electronic device is running, the processor executes the computer program stored in the memory to cause the electronic device to execute instructions for implementing the indoor floor plan construction method based on smartphone acoustic ranging as described in claim 1 or 2.

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