A self-synchronizing acoustic position sensing system

Abstract

The application discloses a self-synchronous acoustic position sensing system, which comprises a master base station and a plurality of slave base stations, the coordinates of the master base station and the slave base stations are known, and the master base station firstly transmits a positioning audio signal; after detecting the positioning audio signal transmitted by the master base station, each slave base station detects the arrival time of the positioning audio signal, and a target to be detected also detects the arrival time of the positioning audio signal transmitted by the master base station; after detecting the positioning audio signal transmitted by the master base station, each slave base station transmits a positioning audio signal after delaying for a set time, the positioning audio signal transmitted by each slave base station is received by the target to be detected, and the arrival time of the positioning audio signal is detected; the target to be detected obtains distance difference information between the target and each base station, and solves the position of the target to be detected in real time according to the distance difference information. The system is self-synchronous by using acoustic devices, and compared with the previous synchronization mode, the system avoids complex connection and radio frequency interference.

Description

TECHNICAL FIELD

[0001] The present application relates to the field of positioning and navigation technology, and in particular to a self-synchronized acoustic location-aware system. BACKGROUND

[0002] Location-aware technologies are mainly divided into radio frequency, motion signal, geomagnetic, image and audio according to the type of signals used for positioning, each of which has its own characteristics. The main ones based on radio frequency are Bluetooth, WIFI, UWB, etc. The Bluetooth and WIFI positioning technologies based on received signal strength indication usually use signal attenuation models for ranging or fingerprinting to achieve positioning. The disadvantages are low positioning accuracy (meter level), large workload of offline fingerprint collection and update, and signal attenuation model is easily disturbed by the environment. The location-aware technologies based on angle of arrival of antenna array, round trip time of WIFI and channel state information, UWB ranging, etc. can provide high-precision positioning from centimeter to sub-meter level, but they need wireless base stations and intelligent terminals to support related protocols, and the complexity of deployment is high, and the cost of wide coverage is very high. Pedestrian Dead Reckoning (PDR) and geomagnetic based on motion signals both have the advantages of no need for additional infrastructure and compatibility with mobile phones, but the former has cumulative error and cannot achieve accurate positioning for a long time, and often needs to be combined with other positioning technologies, and the latter has low positioning accuracy (meter level) and needs to collect the distribution of indoor geomagnetic field offline. The computer vision positioning method based on image can achieve high-precision positioning of the target, but it needs to pre-establish an image feature library, the hardware cost is high and the calculation is complex, and the performance is easily affected by the environment texture and shooting conditions.

[0003] The location-aware technology based on audio uses acoustic devices such as microphones and loudspeakers to achieve positioning. To support high concurrency, it usually adopts the architecture of base stations transmitting audio and terminals receiving and processing. The above-mentioned location-aware technology based on audio usually uses Time Difference of Arrival (TDoA) based on signal arrival time difference, i.e. the time difference of audio transmitted by each acoustic base station reaching the target, to achieve target positioning and navigation. Accurate detection of TDoA is the key to ensuring the performance of the acoustic location-aware system. In addition to the need for the target to accurately detect the arrival time of the audio, high-precision synchronization between acoustic base stations is also needed. The existing acoustic location-aware systems usually use wireless or wired methods to achieve synchronization. Wireless synchronization mainly uses radio frequency to achieve synchronization between base stations or between base stations and targets, and wired synchronization mainly uses connecting lines to achieve synchronization between base stations. The disadvantages of the above-mentioned synchronization methods are radio frequency interference for wireless synchronization and difficulty in laying for wired synchronization, and the cost of synchronization for both is high. SUMMARY

[0004] The application aims to provide a self-synchronized acoustic position sensing system, which is self-synchronized by using acoustic devices themselves, avoids complex connection and radio frequency interference compared with previous synchronization methods, and greatly reduces synchronization cost.

[0005] The application aims to achieve the above technical solutions.

[0006] A self-synchronized acoustic position sensing system, which comprises a master base station and multiple slave base stations, wherein:

[0007] The coordinates of the master base station and each slave base station are known, and the master base station first transmits a positioning audio signal in a positioning period.

[0008] After detecting the positioning audio signal transmitted by the master base station, each slave base station detects the arrival time of the positioning audio signal, and the target to be detected also detects the arrival time of the positioning audio signal transmitted by the master base station.

[0009] After detecting the positioning audio signal transmitted by the master base station, each slave base station transmits a positioning audio signal after delaying a set time, and the target to be detected receives the positioning audio signal transmitted by each slave base station and detects the arrival time of the positioning audio signal.

[0010] The target to be detected obtains distance difference information between the target and each base station according to the known sound speed, the distance between each base station, the set delay time, and the arrival time of the positioning audio signal transmitted by the master base station and each slave base station detected by the target to be detected, and solves the position of the target in real time according to the distance difference information.

[0011] The above technical solutions provided by the application can be seen that the above system is self-synchronized by using acoustic devices themselves, avoids complex connection and radio frequency interference compared with previous synchronization methods, and greatly reduces synchronization cost. BRIEF DESCRIPTION OF DRAWINGS

[0012] In order to more clearly illustrate the technical solutions of the embodiments of the application, the drawings needed in the embodiment description will be briefly introduced. Obviously, the drawings in the following description are only some embodiments of the application, and other drawings can be obtained by those skilled in the art without creative labor.

[0013] Figure 1 The self-synchronized acoustic position sensing system structure schematic diagram provided for the embodiments of the application;

[0014] Figure 2 The process schematic diagram of the target positioning realized by the system described in the embodiments of the application;

[0015] Figure 3 The time domain diagram of self-synchronous positioning is realized for the system in the embodiment of the present application. DETAILED DESCRIPTION

[0016] The technical solutions in the embodiments of the present application will be clearly and completely described with reference to the drawings in the embodiments of the present application. Obviously, the described embodiments are only a part of the embodiments of the present application, but not all the embodiments of the present application, which do not constitute a limitation of the present application. Based on the embodiments of the present application, all other embodiments obtained by a person of ordinary skill in the art without creative effort belong to the protection scope of the present application.

[0017] As Figure 1 Fig. 1 is a structural schematic diagram of a self-synchronous acoustic position sensing system provided by an embodiment of the present application, which comprises one master base station and multiple slave base stations, wherein:

[0018] The coordinates of the master base station and each slave base station are known. In a specific implementation, the positional relationship of the master base station and the slave base stations is not strictly required. The coordinates of each base station are calibrated by a surveying device, for example, a total station. In a positioning period, the master base station first transmits a positioning audio signal. In a specific implementation, in order to facilitate detection and suppression of background noise, the positioning audio signal is modulated.

[0019] After each slave base station detects the positioning audio signal transmitted by the master base station, the arrival time of the positioning audio signal is detected, and the target to be detected also detects the arrival time of the positioning audio signal transmitted by the master base station.

[0020] After each slave base station detects the positioning audio signal transmitted by the master base station, the positioning audio signal is transmitted after a set time delay. The target to be detected receives the positioning audio signal transmitted by each slave base station, and detects the arrival time of the positioning audio signal.

[0021] The target to be detected obtains the distance difference information between the target and each base station according to the known sound speed, the distance between each base station (which can be calculated according to the known coordinates of the base stations), the set delay time, and the arrival time of the positioning audio signal transmitted by the master base station and each slave base station detected by the target to be detected, and solves the position of the target to be detected in real time according to the distance difference information, thereby realizing positioning of the target.

[0022] Based on the system, the process of positioning of the target to be detected in a positioning period is specifically as follows:

[0023] This embodiment is described by taking two-dimensional positioning as an example, and is also applicable to a three-dimensional case, for example, Figure 2The diagram illustrates the target localization process of the system according to an embodiment of the present invention. It is assumed that there are four acoustic base stations within the localization area, denoted as A, B, C, and D. Base station A is the master base station, and base stations B, C, and D are slave base stations. The coordinates of the corresponding base stations are known. Each base station contains a speaker and a microphone. To ensure high concurrency, the target to be measured (… Figure 2 The Target in the algorithm passively receives audio signals using its built-in microphone and calculates its location by detecting the arrival time of the audio transmitted by each acoustic base station. Figure 3 The figure shown is a time-domain diagram of the system implementing self-synchronization positioning according to an embodiment of the present invention. (Refer to...) Figure 3 The specific process is as follows:

[0024] 1) Within one positioning cycle, for example, 1 second, base station A is at T A The positioning audio signal is constantly transmitted. To facilitate the detection and suppression of background noise, the positioning audio signal is modulated, such as a chirp signal or a quadrature code modulated signal.

[0025] 2) After receiving the positioning audio signal transmitted by base station A, base stations B, C, and D respectively detect the arrival time of the positioning audio signal and use R... B R C and R D express;

[0026] Simultaneously, the target under test also detects the arrival time of the positioning audio signal transmitted by base station A, using R... AT Indicate; at Figure 3 In the middle, t is used respectively AB t AC and t AD Let the time it takes for the audio transmitted by base station A to reach base stations B, C, and D be:

[0027]

[0028] 3) Base station B from time R B Start, delay time t delayB After that, i.e., T B At time R, the positioning audio signal is transmitted, and the target under test is at time R. BT The location audio signal is received at any time, and the time is t. BT ;

[0029] Base station C from time R C Start, delay time t delayC After that, i.e., T C At time R, the positioning audio signal is transmitted, and the target under test is at time R. CT The location audio is received at any time, in time t CT ;

[0030] Base station D from time R D Start, delay time t delayD After that, i.e., T D At time R, the positioning audio signal is transmitted, and the target under test is at time R. DT The location audio is received at any time, in time t DT ;

[0031] 4) According to Figure 3 List the relationships between each time point as shown in the following formula (2), and calculate the distance difference between the target and every two base stations;

[0032]

[0033] Based on equation (2), equation (3) is further derived:

[0034]

[0035] Multiplying both sides of equation (3) by the speed of sound v (unit: m / s) yields equation (4):

[0036]

[0037] Where, d AT d BT d CT and d DT These are the distances between the target object and base stations A, B, C, and D, respectively; R AT R BT R CT and R DT It is the time information extracted from the received positioning audio signal by the target using an audio detection algorithm; d AB d AC and d AD These are the distances between base station A and base stations B, C, and D, respectively.

[0038] In equation (4), d on the right side of the equation AB d AC d AD V, t delayB t delayC t delayD It is known that (R) BT -R AT ), (R CT -R AT ) and (R DT -R AT () is the time interval for detecting the target under test, which is a measured value that can be obtained based on the number of sampling points and the sampling period;

[0039] Therefore, the distance difference information on the left side of equation (4) is determined, including the distance difference (d) between the target and base stations B and A. BT -d AT ), the distance difference (d) between the target and base stations C and A CT -d AT ), the distance difference (d) between the target and base stations D and A DT -d AT );

[0040] 5) Substitute the distance difference information obtained by equation (4) into the positioning algorithm based on time difference of arrival (TDoA) to obtain the position of the target to be measured, and realize the positioning of the target.

[0041] In specific implementations, there are various TDoA-based localization algorithms. This embodiment uses one of them as an example:

[0042] This embodiment adopts a combined weighted positioning method based on TDoA. This method first obtains the positioning results of all different three-base station combinations and their corresponding Cramer-Rao Lower Bound (CRLB). Then, these positioning results are weighted and summed to obtain the final position. The weight is determined by CRLB. The smaller the CRLB, the larger the weight, and vice versa.

[0043] In practice, each base station includes a speaker and a microphone sensor;

[0044] The main base station uses a loudspeaker to transmit positioning audio signals.

[0045] The base station receives the positioning audio signal transmitted by the main base station using a microphone, detects the arrival time, and then transmits the positioning audio signal using a speaker after a set delay.

[0046] The target under test passively senses the positioning audio signals transmitted by the main base station and the slave base station throughout the entire positioning period using its built-in microphone sensor, and detects the arrival time of the audio.

[0047] In addition, when the system is applied to two-dimensional positioning, the total number of base stations should be greater than or equal to 3; when the system is applied to three-dimensional positioning, the total number of base stations should be greater than or equal to 4.

[0048] It is worth noting that the contents not described in detail in the embodiments of the present invention belong to the prior art known to those skilled in the art.

[0049] To sum up, in the target positioning process, the system of the embodiment of the application only receives the positioning audio signals transmitted by the base station, and there is no interaction between the target and the base station, so that the system has the characteristics of supporting high concurrency, that is, supporting unlimited number of users; the system realizes self-synchronization through the transmitted positioning audio, and there is no connection line between the base stations, so that the system is convenient to install and lay out, and the problem of radio frequency interference existing in the traditional radio frequency synchronization is avoided; in addition, considering that the acoustic devices such as loudspeakers and microphone sensors are relatively cheap, the synchronization cost of the acoustic position sensing system of the embodiment of the application is relatively low.

[0050] The above merely describes preferred specific embodiments of the present application, but the protection scope of the present application is not limited thereto, any changes or replacements within the technical scope disclosed by the present application can be easily thought of by those skilled in the art, and should be covered within the protection scope of the present application. Therefore, the protection scope of the present application should be subject to the protection scope of the claims. The information disclosed in the background section of the present application is merely intended to deepen the understanding of the overall background of the present application, and should not be regarded as acknowledging or implying in any form that the information constitutes the prior art known by those skilled in the art.

Claims

1. A self-synchronizing acoustic position sensing system, characterized by The system comprises a master base station and multiple slave base stations, wherein: The coordinates of the master base station and each slave base station are known, and in a positioning period, the master base station first transmits a positioning audio signal; After each slave base station detects the positioning audio signal transmitted by the master base station, it detects the arrival time of the positioning audio signal respectively, and at the same time, the target to be measured also detects the arrival time of the positioning audio signal transmitted by the master base station; After each slave base station detects the positioning audio signal transmitted by the master base station, it transmits a positioning audio signal after a set delay, and the target to be measured receives the positioning audio signal transmitted by each slave base station and detects the arrival time of the positioning audio signal; The target to be measured obtains the distance difference information between the target and each base station according to the known sound speed, the distance between each base station, the set delay time, and the arrival time of the positioning audio signal transmitted by the master base station and each slave base station detected by the target to be measured, and calculates the position of the target to be measured in real time according to the distance difference information, thereby realizing the positioning of the target; Based on the system, in a positioning period, the process of realizing the positioning of the target to be measured is as follows: Suppose there are four acoustic base stations in the positioning area, which are represented by A, B, C, and D respectively, the base station A is the master base station, and the base stations B, C, and D are slave base stations, and the coordinates of the corresponding base stations are known, and the specific process is as follows: 1) In one positioning cycle, the base station A transmits a positioning audio signal at time T A ; 2) After receiving the positioning audio signal transmitted by base station A, base stations B, C and D respectively detect the arrival time of the positioning audio signal, and respectively represent them as R B , R C and R D , respectively. At the same time, the target to be measured also detects the arrival time of the positioning audio signal transmitted by the base station A, denoted by R AT ; the time taken for the audio transmitted by the base station A to arrive at the base stations B, C and D is denoted by t AB , t AC and t AD , respectively, so that 3) The base station B starts transmitting the positioning audio signal at time R B , after a delay time t delayB , at time T B , the measured object receives the positioning audio signal at time R BT , with a time t BT ; The base station C starts transmitting the positioning audio signal at time R C , delays for a time t delayC , and then starts transmitting the positioning audio signal at time T C , at which time the target under test receives the positioning audio at time R CT , with a time t CT . The base station D starts transmitting the positioning audio signal at time R D , delays for a time t delayD , and then starts transmitting the positioning audio signal at time T D , at which time the object under test receives the positioning audio at time R DT , with a time t DT ; 4) list the relationship between each time and time, as shown in the following formula (2), and calculate the distance difference between the target and each two base stations; According to formula (2), formula (3) is further derived: Multiply the sound speed v on both sides of the equal sign in formula (3) to obtain formula (4): wherein d AT , d BT , d CT and d DT are the distances between the target to be measured and the base stations A, B, C and D respectively; R AT , R BT , R CT and R DT are the time information extracted by the target to be measured from the received positioning audio signals using an audio detection algorithm; d AB , d AC and d AD are the distances between the base stations A and the base stations B, C and D respectively; In formula (4), d AB , d AC , d AD , v, t delayB , t delayC , t delayD are known, (R BT -R AT ), (R CT -R AT ) and (R DT -R AT ) are time intervals to be detected, and t is a measured value, which can be obtained according to the number of sampling points and the sampling period. Thus, the distance difference information on the left side of equation (4) is determined, including the distance difference (d BT -d AT ) between the target and base station B and A, the distance difference (d CT -d AT ) between the target and base station C and A, and the distance difference (d DT -d AT ) between the target and base station D and A. 5) substitute the distance difference information obtained by using formula (4) into the TDoA positioning algorithm to obtain the position of the target to be measured, thereby realizing the positioning of the target.

2. The self-synchronizing acoustic position sensing system of claim 1, wherein, Each base station comprises a loudspeaker and a microphone sensor; The master base station transmits a positioning audio signal using the loudspeaker; The slave base station receives the positioning audio signal transmitted by the master base station using the microphone, detects the arrival time, and then transmits a positioning audio signal using the loudspeaker after a set delay; The target to be measured passively perceives the positioning audio signal transmitted by the master base station and the slave base station in the entire positioning period using the self-provided microphone sensor, and detects the audio arrival time.

3. The self-synchronous acoustic position sensing system according to claim 1, wherein: When the system is applied to two-dimensional positioning, the total number of base stations should be greater than or equal to 3; When the system is applied to three-dimensional positioning, the total number of base stations should be greater than or equal to 4.

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