An ultrasonic indoor three-dimensional positioning system and method

Abstract

The application discloses an ultrasonic indoor three-dimensional positioning system and method. The ultrasonic indoor three-dimensional positioning system comprises a central control module, a transmitting module and a receiving module. The central control module comprises a central control unit, a sound velocity correction module and a wireless communication module. The transmitting module comprises a transmitting control unit, an ultrasonic transmitting module and a wireless communication module. The receiving module comprises a receiving processing unit, a wireless communication module and an ultrasonic receiving module. The ultrasonic transmitting module adopts a PMUT with a directivity of 180 DEG, comprises area positioning ultrasonic transducers composed of one or more low-frequency ultrasonic transducers with different frequencies, and position positioning ultrasonic transducers composed of more than three high-frequency ultrasonic transducers with different frequencies. The ultrasonic receiving module adopts a wideband microphone. The ultrasonic indoor three-dimensional positioning system can realize accurate three-dimensional positioning in a large range, and the positioning precision reaches millimeter level.

Description

TECHNICAL FIELD

[0001] The present application belongs to the field of spatial positioning, in particular to an ultrasonic indoor three-dimensional positioning system and method. BACKGROUND

[0002] Indoor positioning refers to the realization of position positioning in an indoor environment, mainly using wireless communication, base station positioning, inertial navigation positioning, motion capture and other technologies to form an indoor position positioning system, so as to realize the position monitoring of personnel, objects and the like in the indoor space. Indoor positioning technology has broad application prospects, and can be combined with mobile Internet, cloud computing, big data, high-performance computers and other technologies to form new comprehensive applications, broaden the application range in the fields of spatial infrastructure services, disaster and emergency rescue, public safety, medical health and pension services, and promote technological innovation and business model innovation.

[0003] At present, commonly used indoor positioning technologies include Wi-Fi, Bluetooth, infrared, RFID, ZigBee and ultrasonic positioning. Among them, ultrasonic positioning mainly adopts reflective ranging (after transmitting ultrasonic waves and receiving the echo generated by the measured object, the distance between the two is calculated according to the time difference between the echo and the transmitted wave), and determines the position of the object through a triangular positioning algorithm. The ultrasonic positioning system is composed of a main distance meter and a plurality of electronic tags. The main distance meter is placed at the position to be positioned in the space, and each electronic tag is placed at a fixed position in the indoor space. First, the main distance meter sends ultrasonic signals to each electronic tag, and the electronic tag reflects the transmission to the main distance meter after receiving the signal, so that the distance between each electronic tag and the main distance meter can be determined, and the positioning coordinates can be obtained. The overall positioning accuracy of ultrasonic positioning is high, which can reach centimeter level. The disadvantage is that the attenuation and interference of ultrasonic waves in the transmission process affect the effective range of positioning and reduce the positioning accuracy. SUMMARY

[0004] The purpose of the present application is to provide an ultrasonic indoor three-dimensional positioning system, which solves the technical problems of limited positioning range, weak stability, and positioning accuracy easily affected by attenuation and interference of the ultrasonic positioning system. The ultrasonic indoor three-dimensional positioning system of the present application can realize accurate three-dimensional positioning in a large range, and the positioning accuracy reaches millimeter level.

[0005] Another purpose of the present application is to provide an indoor three-dimensional ultrasonic positioning method based on the ultrasonic indoor three-dimensional positioning system.

[0006] To achieve the above purpose, the present application adopts the following technical solutions:

[0007] An ultrasonic indoor three-dimensional positioning system, characterized in that it comprises a central control module, a transmitting module and a receiving module, wherein:

[0008] The central control module comprises a central control unit, a sound speed correction module and a wireless communication module; the wireless communication module emits wireless signals to the region to be positioned, and communicates with the transmitting module and the receiving module, wherein the wireless signals contain clock, sound speed and coordinate information of the ultrasonic transducer; the central control unit comprises a microcontroller unit (MCU), a clock source and a storage unit, and calculates and stores information including sound speed, spatial coordinates of the ultrasonic transducer, and controls wireless communication;

[0009] The transmitting module comprises a transmitting control unit, an ultrasonic transmitting module and a wireless communication module; the ultrasonic transmitting module comprises region positioning ultrasonic transducers and position positioning ultrasonic transducers arranged in the region to be positioned; the region positioning ultrasonic transducers are composed of one or more low-frequency ultrasonic transducers with different frequencies; the position positioning ultrasonic transducers are composed of more than three high-frequency ultrasonic transducers with different frequencies; the transmitting control unit comprises a microcontroller unit (MCU), a clock source, a storage unit and an ultrasonic transducer driving module, which drives the region positioning or position positioning ultrasonic transducers to emit ultrasonic waves to the region to be positioned; the wireless communication module communicates with the central control module;

[0010] The receiving module comprises a receiving processing unit, a wireless communication module and an ultrasonic receiving module; the ultrasonic receiving module is a wideband microphone, which receives ultrasonic signals from the transmitting module; the wireless communication module receives wireless signals from the central control module; the receiving processing unit comprises a signal processing module, an MCU and a storage unit; the data processing and operation program executed by the receiving processing unit comprises the following steps: determining the starting point of the transmission time of the ultrasonic wave through the wireless signal, amplifying, filtering, collecting, time-frequency transforming and envelope line processing the received ultrasonic signal, extracting the time of flight (TOF) of the ultrasonic wave from the processed time-domain signal, determining the ultrasonic transducer participating in positioning from the frequency-domain signal, obtaining the coordinate information of the ultrasonic transducer from the wireless signal, determining the current region by the region positioning ultrasonic transducer, and calculating the position of the receiving module using the time of flight and the coordinate information of the position positioning ultrasonic transducer.

[0011] The sound speed correction module comprises a temperature and humidity measuring unit and a pressure measuring unit, which are used to measure the ambient temperature, humidity and atmospheric pressure to correct the atmospheric sound speed of the region to be positioned.

[0012] The area positioning ultrasonic transducer can be selected according to the size of the space to be positioned, in particular, when the space to be positioned is small and does not need to be divided into areas, the area positioning ultrasonic transducer can be omitted; when the space to be positioned is large, a combination of multiple low-frequency ultrasonic transducers of different frequencies can be selected as the area positioning ultrasonic transducer, and different combinations of low-frequency ultrasonic transducers correspond to different spatial areas divided in the space to be positioned. In a certain divided spatial area, more than two groups of the same area positioning ultrasonic transducers can be arranged at different positions to ensure that the area positioning signal can completely cover the area.

[0013] Preferably, the frequency range of the low-frequency ultrasonic transducer is generally 20KHz-50KHz, and as an area positioning transducer, its propagation distance is generally greater than 10 meters. The frequency range of the high-frequency ultrasonic transducer is generally 50K-100KHz, and as a position positioning transducer, its propagation distance is generally greater than 5 meters.

[0014] Preferably, the low-frequency or high-frequency ultrasonic transducer adopts a piezoelectric micro-machined ultrasonic transducer (PMUT). The directivity of the PMUT can generally reach 180°, thereby covering the entire space or area to be positioned.

[0015] In the present application, an omnidirectional wideband microphone is used in the ultrasonic receiving module, and its directivity is 180°. The frequency band range of the wideband microphone can cover at least the frequency band range of the low-frequency or high-frequency ultrasonic transducer. Preferably, the wideband microphone is more than two, and is arranged at different positions of the receiving module.

[0016] Further, the wireless communication module of the central control module, the transmitting module and the receiving module can be composed of radio broadcast, Wi-Fi, ZigBee, Bluetooth, etc.

[0017] Based on the ultrasonic indoor three-dimensional positioning system, the application further provides an indoor three-dimensional ultrasonic positioning method, which comprises the following steps:

[0018] Specifically, the indoor three-dimensional ultrasonic positioning method comprises the following steps:

[0019] (1) The central control unit drives the sound velocity correction module to collect atmospheric temperature, humidity and pressure information, and corrects the sound velocity, and drives the wireless communication module to transmit wireless signals to the space to be positioned, and communicates with the transmitting module and the receiving module, wherein the wireless signals contain the atmospheric sound velocity in the space to be positioned, the clock for driving ultrasonic transmission and the coordinate information of the ultrasonic transducer;

[0020] (2) After the transmitting module receives the wireless signal containing the transmission instruction from the central control module, the transmission control unit drives the region positioning and position positioning ultrasonic transducers to transmit ultrasonic signals to the space to be positioned;

[0021] (3) The receiving module receives the ultrasonic signals from the transmitting module through the wideband microphone, and receives the wireless signals from the central control module through the wireless communication module, wherein the wireless signals contain the same clock for ultrasonic transmission, the atmospheric sound velocity and the position information of the ultrasonic transducer; the receiving processing unit reads the atmospheric sound velocity in the current space, the time starting point of ultrasonic transmission and the position coordinate information of each ultrasonic transducer from the received wireless signals and stores them, amplifies, band-pass filters and finally samples and stores the ultrasonic signals received by the wideband microphone;

[0022] (4) the receiving processing unit transforms the ultrasonic time domain signal into a frequency domain signal by performing a discrete Fourier transform on the digital signal obtained by sampling the ultrasonic signal; determines which frequencies of the ultrasonic transducers participate in the current positioning from the frequency domain signal, and reads the position coordinate information of the ultrasonic transducers in the storage unit, and then determines the current region by the region positioning ultrasonic transducer; obtains the envelope of the time domain signal by Hilbert transform on the time domain signal, and obtains the time of flight (TOF) of the ultrasonic waves emitted by each position positioning ultrasonic transducer participating in the current positioning from emission to reception through the envelope of the time domain signal, and selects the three with smaller values (closest to the receiving module) from the TOF time to solve the position of the receiving module;

[0023] (5) the position information of the receiving module is calculated using the ultrasonic wave propagation TOF and the position coordinates of the position positioning transducers, and the formula is as follows:

[0024]

[0025] In the formula, the coordinates of the receiving module are (x, y, z), the three-dimensional coordinates of the three position positioning transducers are (x1, y1, z1), (x2, y2, z2), and (x3, y3, z3), respectively, c is the atmospheric sound speed, and t1, t2, and t3 are the time of flight (TOF) of the ultrasonic waves emitted by the three position positioning transducers from emission to reception.

[0026] Beneficial effects: the omnidirectional ultrasonic transducer is used as the emission mode in the present application, which can realize millimeter-level positioning at any position in the indoor space; a wideband microphone is used as the receiver, which can simplify the ultrasonic receiving system and improve the universality of the receiver; at the same time, the combination of the region positioning transducer and the position positioning transducer can realize accurate three-dimensional positioning in a large range of space; at the same time, the present application can support an unlimited number of receiving modules for positioning. BRIEF DESCRIPTION OF DRAWINGS

[0027] Figure 1 It is a structural schematic diagram of the ultrasonic indoor three-dimensional positioning system of the present application;

[0028] Figure 2 It is a schematic diagram of indoor three-dimensional ultrasonic positioning;

[0029] Figure 3 It is a schematic diagram of the time domain signal of the ultrasonic signal received by the receiving module;

[0030] Figure 4 It is a schematic diagram of the frequency domain signal of the ultrasonic signal received by the receiving module. DETAILED DESCRIPTION

[0031] In order to make the objects, technical solutions and advantages of the present application clearer, the present application will be further described in detail below with reference to the embodiments. It should be understood that the specific embodiments described below are only used to explain the present application and not used to limit the present application. The protection scope of the present application is not limited by the specific embodiments, but is determined by the claims.

[0032] As shown in Figure 1 An ultrasonic indoor three-dimensional positioning system, comprising a central control module, a transmitting module and a receiving module. The central control module comprises a central control unit, a sound velocity correction module and a wireless communication module; the central control unit comprises a microcontroller unit (MCU), a clock source and a storage unit, used for sound velocity correction, calculation and storage of ultrasonic transducer spatial coordinates and other information, and control of the wireless communication module to realize communication; the sound velocity correction module mainly comprises a temperature and humidity measurement unit and a pressure measurement unit, used for measuring environmental temperature, humidity and atmospheric pressure to correct the atmospheric sound velocity of the space to be positioned; the wireless communication module transmits wireless signals containing clock information, sound velocity information and ultrasonic transducer coordinate information, which can be composed of radio broadcast, Wi-Fi, ZigBee, Bluetooth, etc.

[0033] The transmitting module comprises a transmitting control unit, a wireless communication module and an ultrasonic transmitting module. The ultrasonic transmitting module is composed of area positioning ultrasonic transducers and position positioning ultrasonic transducers; the area positioning ultrasonic transducers are composed of one or multiple low-frequency ultrasonic transducers with different frequencies (T1, T2, T3, …), and the frequency range can usually be selected within 20KHz-50KHz. The number of area positioning ultrasonic transducers can be selected according to the size of the space to be positioned, especially when the space to be positioned is small, the area positioning ultrasonic transducers can be omitted; when the space to be positioned is large, multiple low-frequency ultrasonic transducers with different frequencies can be selected as area positioning ultrasonic transducers; different combinations of low-frequency ultrasonic transducers correspond to different spatial areas in the space to be positioned. For example, when 31 low-frequency ultrasonic transducers with frequencies of 20KHz, 21KHz, 22KHz, …, 50KHz are selected, every 3 ultrasonic transducers with different frequencies are selected as a group of area positioning ultrasonic transducers, and 4495 (number of combinations ) independent spaces can be positioned.

[0034] The position positioning ultrasonic transducer is composed of a group of high-frequency ultrasonic transducers (S1, S2, S3, S4, S5, …) with different frequencies, and the frequency range can be usually selected in the range of 50 KHz-100 KHz. The number thereof is usually several to dozens, and is used for positioning a specific position in a region. According to the technical scheme of the application, the combination of at least three position positioning ultrasonic transducers not on the same straight line can determine the position of the receiving module in space.

[0035] The application distinguishes the region positioning ultrasonic transducer and the position positioning ultrasonic transducer, and adopts two ultrasonic transducers with different frequencies. Since the low-frequency ultrasonic wave attenuates slowly in air and has a large effective propagation range, the use of the low-frequency transducer as the region positioning transducer can ensure that the receiving module in the action region thereof can receive the region positioning ultrasonic signal. The high-frequency ultrasonic wave attenuates fast in air and has a small action range, but the positioning precision thereof is higher than that of the low-frequency ultrasonic transducer.

[0036] The low-frequency or high-frequency ultrasonic transducer is recommended to be a piezoelectric micro-mechanical ultrasonic transducer (PMUT). In the field of ultrasonic positioning, the direction angle of the conventional ultrasonic transducer is usually small, and there is a large blind area during positioning. The directivity of the PMUT can usually reach 180°, thereby covering the whole space region to be positioned. The PMUT can be selected according to the frequency. Generally, the PMUT structure includes a substrate layer, a support layer and a structure layer. The structure layer above the support layer is usually composed of a piezoelectric layer, an upper electrode and a lower electrode. The support layer and part of the etched structure layer form a vibrating diaphragm. The substrate layer is partially etched to form a cavity structure corresponding to the vibrating diaphragm below the support layer. The vibrating diaphragm and the corresponding cavity structure form a PMUT vibration element. The PMUT vibration element emits ultrasonic waves with a corresponding frequency after being driven by a circuit.

[0037] The emission control unit includes a microcontroller unit (MCU), a clock source, a storage unit, an ultrasonic transducer driving module and the like. The emission control unit drives the region or position positioning ultrasonic transducer to emit ultrasonic waves to the space to be positioned.

[0038] The receiving module comprises a receiving processing unit, a wireless communication module and an ultrasonic receiving module. As an ultrasonic signal receiver corresponding to the low-frequency or high-frequency ultrasonic transducer in the ultrasonic transmitting module, an omnidirectional wideband microphone is used in the ultrasonic receiving module to receive ultrasonic signals of different frequencies from various directions. If a conventional ultrasonic transducer is used as the receiving unit, since the ultrasonic transducer generally has a small bandwidth, more receiving transducers are needed to receive ultrasonic signals of a wider frequency range, thereby increasing the complexity and manufacturing cost of the receiving system, and more receiving ultrasonic transducers will reduce the positioning accuracy. The omnidirectional wideband microphone has a frequency range covering at least the frequency range of the low-frequency or high-frequency ultrasonic transducer, and the directivity of the omnidirectional wideband microphone is generally 180°.

[0039] The receiving processing unit comprises an ultrasonic signal amplification, filtering, acquisition and storage circuit, module or chip, an MCU for executing signal or data processing and operation programs and a storage unit. The receiving processing unit determines the starting point of the transmission time of the ultrasonic transducer through wireless signals, amplifies, filters, acquires and performs time-frequency conversion on the ultrasonic signals, extracts the time of flight (TOF) of the ultrasonic wave from the transmission to the reception from the processed time-domain signals, obtains the coordinate information of the area positioning ultrasonic transducer and the position positioning ultrasonic transducer in the space from the processed frequency-domain signals, and calculates the position information of the receiving module using the ultrasonic wave propagation time information and the position coordinate information of the ultrasonic transducer.

[0040] The wireless communication modules in the transmitting module and the receiving module are matched with the central control module and can be composed of radio broadcasting, Wi-Fi, ZigBee, Bluetooth, etc. Generally, the wireless communication between the central control module and the transmitting module is bidirectional communication, and the communication between the central control module and the receiving module is unidirectional communication, i.e. the wireless communication module in the receiving module is only used to receive wireless signals from the central control module.

[0041] The ultrasonic indoor three-dimensional positioning system and the indoor three-dimensional ultrasonic positioning method according to the present application are used to realize the following functions:

[0042] The central control unit drives the sound velocity correction module to collect and calculate sound velocity correction information, and drives the wireless communication module of the central control module to transmit wireless signals containing clock, sound velocity and ultrasonic transducer coordinate information; after receiving the wireless signals containing transmission instructions from the central control module, the transmission control unit drives the area positioning ultrasonic transducer and the position positioning ultrasonic transducer to transmit ultrasonic signals to the space to be positioned; the receiving module receives the ultrasonic signals from the transmission module through a wideband microphone, and receives the wireless signals from the central control module through the wireless communication module, wherein the wireless signals contain the same clock, atmospheric sound velocity and position information of the ultrasonic transducer of the ultrasonic wave transmission, the receiving processing unit determines the starting point of the ultrasonic wave transmission time through the wireless signals, processes the ultrasonic signals received by the wideband microphone, extracts the time of flight (TOF) of the ultrasonic wave from the transmission to the reception from the processed time domain signals, determines the area positioning ultrasonic transducer and the position positioning ultrasonic transducer participating in this positioning from the processed frequency domain signals, and obtains the position coordinate information of the ultrasonic transducers from the wireless signals, and calculates the position information of the receiving module according to the TOF of the ultrasonic wave propagation and the position coordinates of the ultrasonic transducers.

[0043] Specifically, the indoor three-dimensional ultrasonic positioning method of the application comprises the following steps:

[0044] (1) The central control unit drives the sound velocity correction module to collect atmospheric temperature, humidity and pressure information, and corrects the sound velocity, and the central control unit drives the wireless communication module to transmit wireless signals to the positioning space to communicate with the transmission module and the receiving module, wherein the wireless signals contain atmospheric sound velocity information in the current positioning space, clock information of ultrasonic transmission and position information of ultrasonic transducers. The central control module is installed in the positioning space, and it is necessary to ensure that the sensors of the sound velocity correction module can work normally, and at the same time, it is necessary to ensure that the wireless signals are not blocked.

[0045] (2) After receiving the transmission instructions contained in the wireless signals from the central control module, the transmission control unit drives the area positioning and position positioning ultrasonic transducers to transmit ultrasonic signals to the space to be positioned, wherein the ultrasonic signals are generated by a plurality of omnidirectional (180°) ultrasonic transducers with different frequencies.

[0046] In the specific implementation of the application, the transmission control unit and the wireless communication module in the transmission module can be assembled together, the above-mentioned assembled module and the ultrasonic transducer are installed in the space to be positioned, and the ultrasonic transducer is connected with the ultrasonic drive port in the transmission module through a wire, and when installing, it is necessary to ensure that the ultrasonic emitted by the ultrasonic transducer is not blocked, and the arrangement position of the ultrasonic transducer should ensure that it does not affect the positioning activities outside the area, and at the same time, the ultrasonic transducer needs to ensure that any three position positioning ultrasonic transducers are not on the same straight line.

[0047] The coordinate system is established with a certain point in space as the coordinate origin, which can usually be selected as the installation position of the emission control unit, the coordinate positions of the ultrasonic transducers are determined, and finally the information of the installed ultrasonic transducer region and the position coordinate information are recorded in the central control module.

[0048] (3) The receiving module receives the ultrasonic signals from the emission module through the omnidirectional broadband microphone and receives the wireless signals from the central control module through the wireless communication module. The receiving processing unit reads the atmospheric sound speed in the current space, the time starting point of ultrasonic wave emission, and the position coordinate information of each ultrasonic transducer from the received wireless signals and stores them. The receiving processing unit amplifies, band-pass filters, and finally samples and stores the ultrasonic signals received by the omnidirectional broadband microphone.

[0049] The receiving module can usually adopt an integrated design. In order to increase the reliability of positioning, two or more omnidirectional broadband microphones can be arranged at different positions in a receiving module as receiving units, so as to avoid the situation that ultrasonic signals cannot be received due to shielding.

[0050] (4) The receiving processing unit performs discrete Fourier transform on the digital signals obtained by sampling the ultrasonic signals, converts the ultrasonic time domain signals into frequency domain signals, determines which frequency ultrasonic transducers participate in this positioning from the frequency domain signals, and then determines the current region by the region positioning ultrasonic transducer, and obtains the spatial coordinates of the above ultrasonic transducers by looking up the position coordinate information of the ultrasonic transducers in the storage unit. The envelope of the time domain signal is obtained by Hilbert transform of the time domain signal. The flight time TOF of the ultrasonic waves emitted by each position positioning ultrasonic transducer from emission to reception is obtained through the envelope of the time domain signal, and the three ultrasonic transducers with smaller TOF values (closest to the receiving module) are selected to solve the position of the receiving module.

[0051] (5) The position information of the receiving module can be calculated using the ultrasonic wave propagation time information and the position coordinate information of the position positioning transducer. The position calculation of the receiving module adopts the following formula:

[0052]

[0053] In the formula, the coordinates of the receiving module are (x, y, z), the three-dimensional coordinates of the three position positioning transducers are (x1, y1, z1), (x2, y2, z2), and (x3, y3, z3) respectively, c is the atmospheric sound speed, and t1, t2, and t3 are the flight times TOF of the ultrasonic waves emitted by the three position positioning transducers from emission to reception.

[0054] As Figure 2As shown, a central control module C is arranged in the region to be positioned, and a larger space is divided into several subspaces by a plurality of transmitting modules Z1, Z2, Z3, each of which has two groups of region positioning transducers (T1T2T3, T1T2T4, T1T2T5, …) and eight position positioning transducers (S1, S2, S3, …S8). Figure 2 As shown, the receiving module R is located in the region (Z1) identified by the T1T2T3 transducer group, and the receiving module R receives ultrasonic signals from the transducers T1T2T3, S1, S2, S3, S4. Figure 3 The frequency domain signal ( Figure 4 ) can be obtained by performing discrete Fourier transform on the received ultrasonic time domain signal. From the frequency domain signal, three low-frequency signals f1, f2, f3 emitted by the region positioning ultrasonic transducers T1, T2, T3 and four high-frequency signals f S1 , f S2 , f S3 , f S4 emitted by the position positioning ultrasonic transducers S1, S2, S3, S4 can be obtained, and further, the TOF information (TOF S1 , TOF S2 , TOF S3 , TOF S4 , …) of the position positioning ultrasonic transducers to the receiving module can be obtained from the time domain signal. Finally, the position coordinates of the receiver can be solved using the coordinate information of at least three position positioning ultrasonic transducers and the corresponding TOF information.

[0055] The above only describes the preferred embodiments of the present application, and it should be noted that for those skilled in the art, without departing from the principles of the present application, a number of improvements and modifications can be made, and these improvements and modifications should also be considered as the protection scope of the present application.

Claims

1. An ultrasonic indoor three-dimensional positioning system, characterized by, The system comprises a central control module, a transmitting module and a receiving module, wherein: The central control module comprises a central control unit, a sound velocity correction module and a wireless communication module; the wireless communication module transmits wireless signals to the area to be positioned, and communicates with the transmitting module and the receiving module; the wireless signals contain clock, sound velocity and coordinate information of the ultrasonic transducers; the central control unit comprises a micro control unit, a clock source and a storage unit, which calculates and stores information including sound velocity and spatial coordinates of the ultrasonic transducers, and controls the wireless communication; The transmitting module comprises a transmitting control unit, an ultrasonic transmitting module and a wireless communication module; the ultrasonic transmitting module comprises area positioning ultrasonic transducers and position positioning ultrasonic transducers arranged in the area to be positioned; the area positioning ultrasonic transducers are composed of low-frequency ultrasonic transducers with different frequencies; the position positioning ultrasonic transducers are composed of high-frequency ultrasonic transducers with different frequencies; the transmitting control unit comprises a micro control unit, a clock source, a storage unit and an ultrasonic transducer driving module, which drives the area positioning ultrasonic transducers or the position positioning ultrasonic transducers to transmit ultrasonic waves to the area to be positioned; the wireless communication module communicates with the central control module; The receiving module comprises a receiving processing unit, a wireless communication module and an ultrasonic receiving module; the ultrasonic receiving module is a wideband microphone, which receives ultrasonic signals from the transmitting module; the wireless communication module receives wireless signals from the central control module; the receiving processing unit comprises a signal processing module, a micro control unit and a storage unit, which performs data processing and operation program, including determining the starting point of the transmission time of the ultrasonic waves through the received wireless signals, amplifying, filtering, collecting, time-frequency transforming and envelope line processing the ultrasonic signals, extracting the flight time of the ultrasonic waves from the transmitting to the receiving from the processed time-domain signals, determining the ultrasonic transducers participating in positioning from the frequency-domain signals, obtaining the coordinate information of the ultrasonic transducers from the wireless signals, determining the current area according to the area positioning ultrasonic transducers, and calculating the position of the receiving module using the flight time and the coordinate information of the position positioning ultrasonic transducers.

2. The ultrasonic indoor three-dimensional positioning system of claim 1, wherein, The area positioning ultrasonic transducers are two or more groups of the same area positioning ultrasonic transducers arranged at different positions in the designated spatial area.

3. The ultrasonic indoor three-dimensional positioning system of claim 1, wherein, The frequency range of the low-frequency ultrasonic transducers is 20KHz-50KHz, and the frequency range of the high-frequency ultrasonic transducers is 50K-100KHz.

4. The ultrasonic indoor three-dimensional positioning system of claim 1, wherein, The low-frequency ultrasonic transducers or the high-frequency ultrasonic transducers are piezoelectric microcomputer ultrasonic transducers, and the directivity is 180°.

5. The ultrasonic indoor three-dimensional positioning system of claim 1, wherein, The frequency range of the wideband microphone is 20KHz-100KHz, and the directivity is 180°.

6. The ultrasonic indoor three-dimensional positioning system of claim 1, wherein, There are two or more wideband microphones arranged at different positions of the receiving module.

7. The ultrasonic indoor three-dimensional positioning system of claim 1, wherein, The wireless communication modules of the central control module, the transmitting module and the receiving module are composed of radio broadcasting, Wi-Fi, ZigBee or Bluetooth.

8. The method of indoor three-dimensional ultrasonic positioning of an ultrasonic indoor three-dimensional positioning system according to any one of claims 1 to 7, comprising: The central control unit of the central control module drives the sound velocity correction module to collect and calculate sound velocity correction information, and drives the wireless communication module to transmit wireless signals containing clock, sound velocity and ultrasonic transducer coordinate information; after receiving the wireless signals containing transmission instructions from the central control module, the transmission module, the transmission control unit drives the area positioning ultrasonic transducer and the position positioning ultrasonic transducer to transmit ultrasonic wave signals to the space to be positioned; the receiving module receives the ultrasonic signals from the transmission module through the wideband microphone, and receives the wireless signals from the central control module through the wireless communication module, the wireless signals containing the clock of ultrasonic wave transmission, the atmospheric sound velocity and the position information of the ultrasonic transducer; the receiving processing unit determines the starting point of the ultrasonic wave transmission time through the wireless signals, processes the ultrasonic signals received by the wideband microphone, extracts the flight time of the ultrasonic wave from transmission to reception from the processed time domain signals, determines the area positioning ultrasonic transducer and the position positioning ultrasonic transducer participating in positioning from the frequency domain signals, and obtains the position coordinate information of the ultrasonic transducers from the wireless signals, calculates the position information of the receiving module according to the ultrasonic wave propagation flight time and the position coordinates of the ultrasonic transducers.

9. The method of indoor three-dimensional ultrasonic positioning according to claim 8, characterized in that, The method comprises the following steps: (1) the central control unit drives the sound velocity correction module to collect atmospheric temperature, humidity and pressure information, and corrects the sound velocity, and drives the wireless communication module to transmit wireless signals to the space to be positioned, and communicates with the transmission module and the receiving module, wherein the wireless signals contain the atmospheric sound velocity in the current positioning space, the clock of driving ultrasonic transmission and the coordinate information of the ultrasonic transducer; (2) after receiving the wireless signals containing transmission instructions from the central control module, the transmission control unit of the transmission module drives the area positioning ultrasonic transducer and the position positioning ultrasonic transducer to transmit ultrasonic wave signals to the space to be positioned; (3) the receiving module receives the ultrasonic signals from the transmission module through the wideband microphone, and receives the wireless signals from the central control module through the wireless communication module, wherein the wireless signals contain the clock of ultrasonic wave transmission, the atmospheric sound velocity and the position information of the ultrasonic transducer; the receiving processing unit reads the atmospheric sound velocity in the current space, the starting point of ultrasonic wave transmission time and the position coordinate information of each ultrasonic transducer from the received wireless signals and stores them, amplifies, bandpass filters and finally samples and stores the ultrasonic signals received by the wideband microphone; (4) the receiving processing unit performs discrete Fourier transform on the digital signals obtained by sampling the ultrasonic signals, converts the ultrasonic time domain signals into frequency domain signals, determines which frequency ultrasonic transducers participate in this positioning from the frequency domain signals, reads the position coordinate information of the ultrasonic transducers in the storage unit, and then determines the current area by the area positioning ultrasonic transducer; the envelope of the time domain signal is obtained by Hilbert transform of the time domain signal, and the flight time TOF of the ultrasonic wave transmitted by each position positioning ultrasonic transducer participating in this positioning from transmission to reception is obtained through the envelope of the time domain signal, and the three values with smaller values are selected from the TOF time for solving the position of the receiving module; (5) The position information of the receiving module is calculated using the time of flight (TOF) of ultrasonic wave propagation and the position coordinates of the position locating transducers, according to the following formula: In the formula, the coordinates of the receiving module are (x, y, z), the three-dimensional coordinates of the three position locating transducers are (x1, y1, z1), (x2, y2, z2), and (x3, y3, z3) respectively, c is the atmospheric sound speed, and t1, t2, and t3 are the time of flight (TOF) of the ultrasonic waves emitted by the three position locating transducers from emission to reception respectively.

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