CN112394325B - Doppler frequency offset estimation system, method and device for ultrasonic positioning signals - Google Patents

Doppler frequency offset estimation system, method and device for ultrasonic positioning signals Download PDF

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Publication number
CN112394325B
CN112394325B CN201910758469.4A CN201910758469A CN112394325B CN 112394325 B CN112394325 B CN 112394325B CN 201910758469 A CN201910758469 A CN 201910758469A CN 112394325 B CN112394325 B CN 112394325B
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ultrasonic
frequency
signal
positioning
frequency calibration
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CN112394325A (en
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向玮晨
刘广松
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Suzhou Touchair Technology Co ltd
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Suzhou Touchair Technology Co ltd
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    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01S—RADIO DIRECTION-FINDING; RADIO NAVIGATION; DETERMINING DISTANCE OR VELOCITY BY USE OF RADIO WAVES; LOCATING OR PRESENCE-DETECTING BY USE OF THE REFLECTION OR RERADIATION OF RADIO WAVES; ANALOGOUS ARRANGEMENTS USING OTHER WAVES
    • G01S5/00—Position-fixing by co-ordinating two or more direction or position line determinations; Position-fixing by co-ordinating two or more distance determinations
    • G01S5/18—Position-fixing by co-ordinating two or more direction or position line determinations; Position-fixing by co-ordinating two or more distance determinations using ultrasonic, sonic, or infrasonic waves
    • G01S5/24—Position of single direction-finder fixed by determining direction of a plurality of spaced sources of known location

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  • Physics & Mathematics (AREA)
  • Engineering & Computer Science (AREA)
  • General Physics & Mathematics (AREA)
  • Radar, Positioning & Navigation (AREA)
  • Remote Sensing (AREA)
  • Measurement Of Velocity Or Position Using Acoustic Or Ultrasonic Waves (AREA)

Abstract

The invention provides a Doppler frequency offset estimation system, method and device for an ultrasonic positioning signal. The method comprises the following steps: receiving a main ultrasonic positioning signal, a secondary ultrasonic positioning signal and a frequency calibration signal which are transmitted by an ultrasonic transmitting unit; calculating Doppler frequency offset of the frequency calibration signal in a phase-locked loop mode; and calculating Doppler frequency offset of the main ultrasonic positioning signal and the secondary ultrasonic positioning signal based on the Doppler frequency offset of the first center frequency, the second center frequency and the frequency calibration signal, wherein the Doppler frequency offset of the main ultrasonic positioning signal is equal to the Doppler frequency offset of the secondary ultrasonic positioning signal. Frequency offset correction for the main ultrasonic positioning signal and the secondary ultrasonic positioning signal is realized based on the frequency calibration signal, so that the cost can be saved.

Description

Doppler frequency offset estimation system, method and device for ultrasonic positioning signals
Technical Field
The embodiment of the invention relates to the technical field of positioning, in particular to a Doppler frequency offset estimation system, method and device for ultrasonic positioning signals.
Background
With the increasing demand for personal navigation and positioning services, indoor positioning systems have expanded from original positioning functions to many aspects, such as business services, security management, which place demands on higher positioning accuracy and wider coverage areas for navigation positioning of personnel in various environments. At present, an ultrasonic positioning system is one of mainstream positioning systems due to high positioning accuracy and simple structure of the ultrasonic positioning system reaching centimeter level, but the ultrasonic positioning system facing a large indoor scene often needs a plurality of ultrasonic transmitting units to cooperate to completely cover the positioning service in the area.
Regarding the problem of eliminating or reducing the doppler effect of a positioning system in a predetermined space, the current solutions are generally: the Doppler shift is estimated and the estimated frequency deviation is compensated for. For Doppler frequency offset estimation, many solutions are proposed in the industry and academia, such as adding a measuring device to directly calculate the frequency offset, adding an additional receiver to calculate the frequency offset, estimating the joint Doppler frequency offset and carrier frequency offset based on three-dimensional beam forming, and the like.
However, the frequency offset is directly calculated by adding an additional monomer device, so that the cost is greatly increased.
Disclosure of Invention
In view of this, the embodiment of the invention provides a doppler frequency offset estimation system, a method and a device for an ultrasonic positioning signal.
The technical scheme of the embodiment of the invention is as follows:
a doppler frequency offset estimation system for an ultrasonic positioning signal, comprising:
the ultrasonic transmitting unit comprises a main transmitting module, a secondary transmitting module and a controller; wherein the main transmitting module comprises a main ultrasonic transmitter and a frequency calibration signal transmitter; the secondary transmitting module comprises at least three secondary ultrasonic transmitters; a primary ultrasound emitter arranged in the geometric center of the at least three secondary ultrasound emitters, a frequency calibration signal emitter arranged at the periphery of the primary ultrasound emitter; the main ultrasonic transmitter is used for transmitting a main ultrasonic positioning signal; the frequency calibration signal transmitter is used for transmitting a frequency calibration signal; the subsonic transmitter is used for transmitting subsonic positioning signals; the controller is used for controlling the main ultrasonic transmitter, the frequency calibration signal transmitter and the secondary ultrasonic transmitter to transmit simultaneously according to a preset frequency; wherein the primary and secondary ultrasonic positioning signals are modulated onto a first carrier wave having a first center frequency; modulating a frequency calibration signal onto a second carrier having a second center frequency, the second center frequency being greater than the first center frequency, the first carrier being non-overlapping with the second carrier, the frequency calibration signal being a narrowband signal;
The intelligent terminal is used for receiving the main ultrasonic positioning signal, the sub-ultrasonic positioning signal and the frequency calibration signal transmitted by the ultrasonic transmitting unit, calculating Doppler frequency offset of the frequency calibration signal in a phase-locked loop mode, and calculating Doppler frequency offset of the main ultrasonic positioning signal and the sub-ultrasonic positioning signal based on Doppler frequency offset of the first center frequency, the second center frequency and the frequency calibration signal, wherein the Doppler frequency offset of the main ultrasonic positioning signal is equal to the Doppler frequency offset of the sub-ultrasonic positioning signal.
The Doppler frequency offset estimation method of the ultrasonic positioning signal is suitable for Doppler frequency offset estimation of the ultrasonic positioning signal transmitted by an ultrasonic transmitting unit, and the ultrasonic transmitting unit comprises a main transmitting module, a secondary transmitting module and a controller; wherein the main transmitting module comprises a main ultrasonic transmitter and a frequency calibration signal transmitter; the secondary transmitting module comprises at least three secondary ultrasonic transmitters; a primary ultrasound emitter arranged in the geometric center of the at least three secondary ultrasound emitters, a frequency calibration signal emitter arranged at the periphery of the primary ultrasound emitter; the main ultrasonic transmitter is used for transmitting a main ultrasonic positioning signal; the frequency calibration signal transmitter is used for transmitting a frequency calibration signal; the subsonic transmitter is used for transmitting subsonic positioning signals; the controller is used for controlling the main ultrasonic transmitter, the frequency calibration signal transmitter and the secondary ultrasonic transmitter to transmit simultaneously according to a preset frequency; wherein the primary and secondary ultrasonic positioning signals are modulated onto a first carrier wave having a first center frequency; modulating a frequency calibration signal onto a second carrier having a second center frequency, the second center frequency being greater than the first center frequency, the first carrier being non-overlapping with the second carrier, the frequency calibration signal being a narrowband signal; the method comprises the following steps:
Receiving a main ultrasonic positioning signal, a secondary ultrasonic positioning signal and a frequency calibration signal which are transmitted by an ultrasonic transmitting unit;
calculating Doppler frequency offset of the frequency calibration signal in a phase-locked loop mode;
and calculating Doppler frequency offset of the main ultrasonic positioning signal and the secondary ultrasonic positioning signal based on the Doppler frequency offset of the first center frequency, the second center frequency and the frequency calibration signal, wherein the Doppler frequency offset of the main ultrasonic positioning signal is equal to the Doppler frequency offset of the secondary ultrasonic positioning signal.
A doppler frequency offset estimation device for an ultrasound positioning signal, comprising a processor, a memory and a computer program stored on the memory and executable on the processor, which when executed by the processor, implements the steps of the doppler frequency offset estimation method for an ultrasound positioning signal as claimed in any one of the preceding claims.
A computer readable storage medium having stored thereon a computer program which when executed by a processor performs the steps of the doppler bias estimation method of an ultrasound positioning signal as claimed in any one of the preceding claims.
From the above technical solution, the embodiment of the present invention provides a system, a method and a device for estimating doppler frequency offset of an ultrasonic positioning signal. The method comprises the following steps: receiving a main ultrasonic positioning signal, a secondary ultrasonic positioning signal and a frequency calibration signal which are transmitted by an ultrasonic transmitting unit; calculating Doppler frequency offset of the frequency calibration signal in a phase-locked loop mode; and calculating Doppler frequency offset of the main ultrasonic positioning signal and the secondary ultrasonic positioning signal based on the Doppler frequency offset of the first center frequency, the second center frequency and the frequency calibration signal, wherein the Doppler frequency offset of the main ultrasonic positioning signal is equal to the Doppler frequency offset of the secondary ultrasonic positioning signal. Therefore, frequency offset correction for the ultrasonic positioning signals is realized based on the frequency calibration signals, no additional monomer equipment is required to be introduced, and the cost can be saved. In addition, the intensity comparison results of the frequency calibration signals of different ultrasonic transmitting units are used for selecting different positioning strategies, so that the positioning accuracy can be improved. In addition, the correction of Doppler frequency offset is added into the positioning system, so that the positioning effect is improved. And moreover, the intelligent terminal in the weak positioning signal area is accurately positioned, and the wide coverage of the ultrasonic positioning system is improved.
Drawings
Fig. 1 is an exemplary block diagram of an ultrasound positioning system according to the present invention.
Fig. 2 is an exemplary structural diagram of an ultrasonic transmitting unit according to the present invention.
Fig. 3 is an exemplary frequency distribution diagram of an ultrasonic positioning signal and a frequency calibration signal according to the present invention.
Fig. 4 is an exemplary flow chart for determining the doppler frequency offset of an ultrasound positioning signal in accordance with the present invention.
Fig. 5 is a schematic diagram of a distribution of positioning signals of an ultrasound transmitting unit network according to the present invention.
Fig. 6 is a flow chart of a first positioning strategy according to the present invention.
Fig. 7 is a flow chart of a second positioning strategy according to the present invention.
Fig. 8 is a flow chart of a third positioning strategy according to the present invention.
Detailed Description
The present invention will be described in further detail with reference to the accompanying drawings, in order to make the objects, technical solutions and advantages of the present invention more apparent.
For simplicity and clarity of description, the following description sets forth aspects of the invention by describing several exemplary embodiments. Numerous details in the embodiments are provided solely to aid in the understanding of the invention. It will be apparent, however, that the embodiments of the invention may be practiced without limitation to these specific details. Some embodiments are not described in detail in order to avoid unnecessarily obscuring aspects of the present invention, but rather only to present a framework. Hereinafter, "comprising" means "including but not limited to", "according to … …" means "according to at least … …, but not limited to only … …". The term "a" or "an" is used herein to refer to a number of components, either one or more, or at least one, unless otherwise specified.
The embodiment of the invention provides a positioning scheme of a self-adaptive positioning strategy based on the intensity of an ultrasonic positioning signal. Moreover, the embodiment of the invention also provides an ultrasonic positioning system based on Doppler frequency offset correction in a complex environment, which can perform double verification on each ultrasonic positioning signal in the overlapping area of a plurality of ultrasonic positioning signals by utilizing the Doppler frequency offset of the frequency calibration signal. In addition, in the embodiment of the invention, based on Doppler frequency offset correction, an ultrasonic emission group is created by using a super-resolution method, so that the intelligent terminal in a weak positioning signal area is accurately positioned, and the wide coverage of an ultrasonic positioning system is further improved.
Fig. 1 is an exemplary block diagram of an ultrasound positioning system according to the present invention.
As shown in fig. 1, the system includes:
a plurality of ultrasonic transmitting units disposed at respective fixed positions for transmitting respective ultrasonic positioning signals, respectively;
the intelligent terminal is used for comparing the intensity of the ultrasonic positioning signals received from the ultrasonic transmitting units, and determining to execute one of the following positioning strategies based on the comparison result: the intensity of the ultrasonic positioning signals transmitted by one ultrasonic transmitting unit is obviously stronger than that of the ultrasonic positioning signals transmitted by other ultrasonic transmitting units; a second positioning strategy that at least two ultrasonic transmitting units transmit strong ultrasonic positioning signals; and a third positioning strategy that weak ultrasonic positioning signals transmitted by at least two ultrasonic transmitting units are mutually mixed.
In one embodiment, the number of ultrasound transmitting units is 4, and the arrangement points of the 4 ultrasound transmitting units constitute a square.
In one embodiment, the ultrasound positioning signals include a primary ultrasound positioning signal, a secondary ultrasound positioning signal, and a frequency calibration signal (the frequency calibration signal is also an ultrasound signal); the ultrasonic transmitting unit comprises a main transmitting module, a secondary transmitting module and a controller; wherein the main transmitting module comprises a main ultrasonic transmitter and a frequency calibration signal transmitter; the secondary transmitting module comprises at least three secondary ultrasonic transmitters; a primary ultrasound emitter disposed at a geometric center of at least three secondary ultrasound emitters, a frequency calibration signal emitter disposed at a periphery of (e.g., attached to) the primary ultrasound emitter; the main ultrasonic transmitter is used for transmitting a main ultrasonic positioning signal; the frequency calibration signal transmitter is used for transmitting a frequency calibration signal; the subsonic transmitter is used for transmitting subsonic positioning signals; the controller is used for controlling the main ultrasonic transmitter, the frequency calibration signal transmitter and the secondary ultrasonic transmitter to transmit simultaneously according to a preset frequency.
In one embodiment, the intelligent terminal is configured to:
determining to execute a first positioning strategy when the difference between the amplitude of the frequency calibration signal transmitted by one ultrasonic transmitting unit and the amplitude of the frequency calibration signal transmitted by an ultrasonic transmitting unit other than the ultrasonic transmitting unit is greater than a predetermined first threshold value; or (b)
Determining to execute a second positioning strategy when the amplitudes of the frequency calibration signals transmitted by the two ultrasonic transmitting units are both greater than a predetermined second threshold value and the difference of the frequency calibration signals transmitted by the two ultrasonic transmitting units is less than a predetermined third threshold value;
and determining to execute the third positioning strategy when the amplitude of the frequency calibration signal transmitted by each ultrasonic transmitting unit is smaller than a preset fourth threshold value or the difference value of the amplitude of the frequency calibration signals transmitted by any two ultrasonic transmitting units is smaller than a preset fifth threshold value. Preferably, the first positioning strategy includes: calculating Doppler frequency offset of the main ultrasonic positioning signals transmitted by the ultrasonic transmitting units which are obviously stronger than the intensity of other ultrasonic positioning signals; performing frequency offset correction on the main ultrasonic positioning signals and the secondary ultrasonic positioning signals which are transmitted by the ultrasonic transmitting units and are obviously stronger than other ultrasonic positioning signals by utilizing the Doppler frequency offset; from the sub-ultrasonic positioning signals subjected to frequency offset correction, three sub-ultrasonic positioning signals are selected according to the sequence of the signal to noise ratio from large to small; and calculating the coordinates of the intelligent terminal based on the main ultrasonic positioning signal subjected to frequency offset correction and the selected three sub-ultrasonic positioning signals. Preferably, the second positioning strategy includes: calculating respective Doppler frequency offsets of frequency calibration signals transmitted by at least two ultrasonic transmitting units transmitting strong ultrasonic positioning signals; frequency offset correction is carried out on the frequency calibration signals transmitted by the at least two ultrasonic transmitting units by using respective Doppler frequency offsets; comparing the signal to noise ratios of the main ultrasonic positioning signals of the at least two ultrasonic transmitting units after the frequency offset correction, and selecting the ultrasonic transmitting unit corresponding to the main ultrasonic positioning signal with the maximum signal to noise ratio as a target ultrasonic transmitting unit; from the subsonic positioning signals subjected to frequency offset correction of the target ultrasonic transmitting unit, three subsonic positioning signals are selected according to the sequence from the high signal to noise ratio; and calculating the coordinates of the intelligent terminal based on the main ultrasonic positioning signals and the three selected sub-ultrasonic positioning signals after the frequency offset correction of the target ultrasonic transmitting unit. Preferably, the third positioning strategy comprises: calculating respective Doppler frequency offsets of the frequency calibration signals transmitted by all the ultrasonic transmitting units; respectively carrying out frequency offset correction on the frequency calibration signals transmitted by all the ultrasonic transmitting units by utilizing the Doppler frequency offsets; and calculating the coordinates of the intelligent terminal based on the frequency calibration signals transmitted by all the ultrasonic transmitting units after the frequency offset correction.
Fig. 2 is an exemplary structural diagram of an ultrasonic transmitting unit according to the present invention. The ultrasonic transmitting unit includes: the device comprises a main ultrasonic transmitting module, a secondary ultrasonic transmitting module and a controller. The main ultrasonic transmitting module comprises a main ultrasonic transmitter and a frequency calibration signal transmitter, and the secondary ultrasonic transmitting module comprises at least three secondary ultrasonic transmitters. The primary ultrasound transmitters are arranged in the geometric center of each secondary ultrasound transmitter, and the frequency calibration signal transmitter is next to the primary ultrasound transmitter. Illustratively, in fig. 2, each secondary ultrasonic generator is disposed at each vertex of a cross centered on the primary ultrasonic emitter. In practice, the individual secondary ultrasound generators may also be arranged on a circular, triangular, hexagonal, etc. geometry centered on the primary ultrasound emitter, as embodiments of the invention are not limited in this regard.
The main ultrasonic transmitter is used for transmitting a main ultrasonic positioning signal S 0,k Contains positioning information and the ID of the ultrasound transmission unit, where k represents the kth ultrasound transmission unit. The frequency calibration signal transmitter is used for transmitting a frequency calibration signal S f,k ；S f,k Frequency calibration signal S representing a kth ultrasound transmission unit f . Four subsonic transmitters for respectively transmitting subsonic positioning signals containing positioning information, namely S 1,k 、S 2,k 、S 3,k 、S 4,k Wherein S is 1,k Subsonic positioning signals transmitted by the 1 st subsonic transmitter of the kth ultrasonic transmitting unit; s is S 2,k Subsonic positioning signals of the 2 nd subsonic emitter frequency of the kth ultrasonic emitter unit; etc. The controller is used for controlling all transmitters (including a main ultrasonic transmitter, a frequency calibration signal transmitter and a secondary ultrasonic transmitter) to transmit signals at the same time according to a preset frequency, and can be regarded as the clock synchronization of the networking of the ultrasonic transmitting units.
The Doppler frequency offset estimation process of the ultrasonic positioning signal is described below.
Assume that in one ultrasound transmission unit shown in fig. 2: the main ultrasonic transmitter transmits a main ultrasonic positioning signal S 0 ，S 0 The ultrasonic transmitter comprises positioning information and an ID of an ultrasonic transmitting unit; the frequency calibration signal transmitter transmits a frequency calibration signal S f,k Wherein k represents a kth ultrasound transmitting unit; subsonic transmitter transmits subsonic positioning signal S 1 、S 2 、S 3 、S 4 Wherein S is 1 、S 2 、S 3 、S 4 Respectively comprising positioning information; the controller is used for controlling all the transmitters (including a main ultrasonic transmitter and a secondary ultrasonic transmitterThe transmitter and the frequency calibration signal transmitter) transmit signals at the same time according to a preset frequency, and can be regarded as the clock synchronization of the networking of the ultrasonic transmitting units.
Fig. 3 is an exemplary frequency distribution diagram of an ultrasonic positioning signal and a frequency calibration signal according to the present invention.
As can be seen from fig. 3, wherein:
(1) Features of the primary and secondary ultrasound positioning signals:
assuming that the same ultrasound transmitting unit comprises a main ultrasound transmitter and four sub-ultrasound transmitters, the main ultrasound positioning signal and the sub-ultrasound positioning signal S transmitted by the ultrasound transmitting unit 0 ,S 1 ,S 2 ,S 3 ,S 4 Comprising a main ultrasonic positioning signal S 0 And four subsonic positioning signals S 1 、S 2 、S 3 、S 4 . Primary ultrasonic positioning signal and secondary ultrasonic positioning signal S 0 ,S 1 ,S 2 ,S 3 ,S 4 The method is respectively implemented as CDMA orthogonal spreading codes, the baseband bandwidth is 1500Hz, a plurality of users can be simultaneously served, the information is not mutually conflicted, and the method can be used as a signal time synchronization technology for measuring the arrival time of signals. The baseband signals of the primary ultrasonic transmitter and the secondary ultrasonic transmitter are modulated to have the frequency F C,0 On carrier wave of 18500Hz, ultrasonic locating signal S 0 ,S 1 ,S 2 ,S 3 ,S 4 The occupied band bandwidth is 3 kilohertz (KHz), and the band is 17KHz-20KHz.
(2) Frequency calibration signal characteristics:
transmitting ultrasonic positioning signals S 0 ,S 1 ,S 2 ,S 3 ,S 4 The ultrasound transmitting unit of (2) also transmits a frequency calibration signal. The frequency calibration signal is implemented as a BPSK modulated Gold code with a frequency band greater than 20KHz (i.e., greater than the maximum frequency of the ultrasound positioning signal). The bandwidth of each frequency calibration signal occupies hundreds of Hz, and the preferred bandwidth interval is [200Hz,500Hz ]And is a narrowband signal.
When the ultrasonic positioning system comprises a plurality of ultrasonic transmitting units, a plurality of frequency calibration signals S with different center frequencies exist f,k The method comprises the steps of carrying out a first treatment on the surface of the Which is a kind ofAnd k represents the kth ultrasound transmitting unit. Frequency calibration signal S of 1 st ultrasonic transmitting unit f,1 With center frequency F C,1 The method comprises the steps of carrying out a first treatment on the surface of the Frequency calibration signal S of the 2 nd ultrasonic transmitting unit f,2 With center frequency F C,2 .. f,k With center frequency F C,k K is a positive integer of at least 1.
A guard interval is arranged between two adjacent frequency calibration signals, and the bandwidth of the guard interval occupies hundreds of Hz, preferably 200Hz-400Hz. The center frequencies may be set in advance for the frequency calibration signals corresponding to the respective ultrasonic transmission units, respectively, so that it is possible to determine which ultrasonic transmission unit the detected frequency calibration signal corresponds to by detecting the center frequency of the frequency calibration signal.
For example, the corresponding relation between the number of the ultrasonic transmitting unit and the frequency calibration signal transmitted by the ultrasonic transmitting unit is set in a mode that the central frequency is increased. Examples: s is S f,1 Center frequency F of (2) C,1 Is 20600Hz; s is S f,2 Center frequency F of (2) C,2 Is (20000+600 x 2) Hz; … S f,k Center frequency F of (2) C,k Is (20000+600 k) Hz, wherein S f,k Occupies 375Hz bandwidth; then adjacent S f,k The transmit frequency bands are separated by 600Hz in sequence, i.e., the guard bandwidth between two adjacent sets of frequency calibration signals is 225Hz.
In fig. 3, the frequency range of the rectangular frame 60 is 17KHZ to 20KHZ, which is the carrier band of the ultrasonic positioning signal. To the right of rectangular box 60 are shown exemplary four small rectangular boxes. After the corresponding relation between the number of the ultrasonic transmitting unit and the frequency calibration signal transmitted by the ultrasonic transmitting unit is set in a mode of increasing the central frequency, four small rectangular frames sequentially form four frequency calibration signals S f,1 、S f,2 、S f,3 And S is f,4 . Wherein, in order of the direction away from the rectangular frame 60, the frequency ranges corresponding to the four small rectangular frames are S respectively f,1 、S f,2 、S f,3 And S is f,4 Is a carrier band of (a) a carrier band of (b). Wherein the frequency range of the rectangular frame 70 farthest from the rectangular frame 60 is S f,4 Is a carrier frequency band of (a); the frequency range of the rectangular frame 61 closest to the rectangular frame 60 is S f,1 Is a carrier band of (a) a carrier band of (b). That is, the nth small rectangular frame detected is the frequency calibration signal of the nth ultrasound transmitting unit based on the order of the direction away from the rectangular frame 60.
While four frequency calibration signals corresponding to four ultrasound transmitting units are described above by way of example, one skilled in the art will recognize that as the number of ultrasound transmitting units increases, the number of frequency calibration signals increases accordingly, and the embodiments of the present invention are not limited in this regard.
Fig. 4 is an exemplary flow chart for determining the doppler frequency offset of an ultrasound positioning signal in accordance with the present invention. The method is suitable for Doppler frequency offset estimation of an ultrasonic transmitting unit, wherein the ultrasonic transmitting unit comprises a main transmitting module, a secondary transmitting module and a controller; wherein the main transmitting module comprises a main ultrasonic transmitter and a frequency calibration signal transmitter; the secondary transmitting module comprises at least three secondary ultrasonic transmitters; a primary ultrasound emitter arranged in the geometric center of the at least three secondary ultrasound emitters, a frequency calibration signal emitter arranged at the periphery of the primary ultrasound emitter; the main ultrasonic transmitter is used for transmitting a main ultrasonic positioning signal; the frequency calibration signal transmitter is used for transmitting a frequency calibration signal which is also an ultrasonic signal; the subsonic transmitter is used for transmitting subsonic positioning signals; the controller is used for controlling the main ultrasonic transmitter, the frequency calibration signal transmitter and the secondary ultrasonic transmitter to transmit simultaneously according to a preset frequency; the method comprises the following steps:
step 401: receiving a main ultrasonic positioning signal, a secondary ultrasonic positioning signal and a frequency calibration signal which are transmitted by the ultrasonic transmitting unit; wherein the primary and secondary ultrasonic positioning signals are modulated onto a first carrier wave having a first center frequency; modulating a frequency calibration signal onto a second carrier having a second center frequency, the second center frequency being greater than the first center frequency, the first carrier being non-overlapping with the second carrier, the frequency calibration signal being a narrowband signal;
Step 402: the Doppler frequency offset of the frequency calibration signal is calculated by using a Phase Lock Loop (PLL) mode.
Step 403: and calculating Doppler frequency offset of the main ultrasonic positioning signal and the secondary ultrasonic positioning signal based on the Doppler frequency offset of the first center frequency, the second center frequency and the frequency calibration signal, wherein the Doppler frequency offset of the main ultrasonic positioning signal is equal to the Doppler frequency offset of the secondary ultrasonic positioning signal.
Specifically: first, a phase-locked loop PLL (phase lock loop) is used to calculate the frequency calibration signal S of the kth ultrasonic transmitting unit (k is a positive integer greater than or equal to 1) f,k Doppler frequency offset F of (2) D,k The method comprises the steps of carrying out a first treatment on the surface of the Then, calculating Doppler frequency offset F of the main ultrasonic positioning signal of the kth ultrasonic transmitting unit D,0 Wherein:doppler frequency offsets of a main ultrasonic positioning signal and a secondary ultrasonic positioning signal of the same ultrasonic transmitting unit are equal and are F D,0 ；F C,0 Is the center frequency of the first carrier; f (F) C,k Is the center frequency of the second carrier. It can be seen that the number of the first carriers is one, and all the main ultrasonic positioning signals and all the secondary ultrasonic positioning signals of all the ultrasonic transmitting units are carried on the first carriers; the number of second carriers is equal to the number of ultrasound transmission units, wherein one second carrier corresponds to one ultrasound transmission unit.
For example, when k=1, the signal S is calibrated based on the frequency of the 1 st ultrasound transmission unit f,1 Calculating the Doppler frequency offset of the ultrasonic positioning signal of the 1 st ultrasonic transmitting unit as F D,1 . Then, calculating Doppler frequency offset F of the ultrasonic positioning signal of the 1 st ultrasonic transmitting unit D,0 WhereinF C,0 Is the center frequency of the first carrier; f (F) C,1 The center frequency of the first subcarrier 61 is set to start from the direction in which the rectangular frame 60 is distant.
For example, when k=2, the signal S is calibrated based on the frequency of the 2 nd ultrasound transmitting unit f,2 Calculating the Doppler frequency offset of the ultrasonic positioning signal of the 2 nd ultrasonic transmitting unit as F D,2 . However, the method is thatThen, calculating Doppler frequency offset F of ultrasonic positioning signals of the 2 nd ultrasonic transmitting unit D,0 WhereinF C,0 Is the center frequency of the first carrier; f (F) C,1 The center frequency of the second subcarrier 62 is set to start from the direction in which the rectangular frame 60 is distant.
When the Doppler frequency offset calculation method is applied to an ultrasonic positioning system, the following steps can be executed: step one: in an ultrasonic positioning system, an ultrasonic transmitter transmits ultrasonic positioning signals, and a frequency calibration signal transmitter transmits frequency calibration signals at the same time, so that all signals are synchronously transmitted; step two: the intelligent terminal receives an ultrasonic positioning signal and a frequency calibration signal; step three: the intelligent terminal calculates Doppler frequency offset of the frequency calibration signal; step four: the intelligent terminal estimates Doppler frequency offset of the ultrasonic positioning signal based on Doppler frequency offset of the frequency calibration signal; step five: correcting Doppler frequency offset of the ultrasonic positioning signals, and calculating the time of the signals reaching the intelligent terminal by using a CDMA technology; step six: estimating the relative position of the intelligent terminal by using a TDOA algorithm; step seven: the coordinates of the intelligent terminal in the indoor environment are obtained, and accurate positioning of the intelligent terminal is achieved. Exemplary, the correction process includes: firstly, band-pass filtering is carried out on the frequency band where the target signal is located so as to eliminate out-of-band noise and interference. Multiplying the band-pass filtered signal by the original transmission carrier wave of the band-pass filtered signal and performing low-pass filtering to obtain a target baseband signal S (n) without frequency offset correction; aiming at the signal to be corrected, the frequency offset correction formula is as follows: Wherein S (n) is the nth value of the complex number sequence of the target signal demodulated to baseband, F D Is the estimated frequency offset of the target signal, F S For the audio signal sampling frequency, < >>And the nth value of the target signal is obtained after the frequency offset correction.
Fig. 5 is a schematic diagram of a distribution of positioning signals of an ultrasound transmitting unit network according to the present invention. In fig. 5, four ultrasonic transmitting units shown in fig. 2 are included, respectively an ultrasonic transmitting unit 10, an ultrasonic transmitting unit 20, an ultrasonic transmitting unit 30, and an ultrasonic transmitting unit 40, wherein the ultrasonic transmitting unit 10, the ultrasonic transmitting unit 20, the ultrasonic transmitting unit 30, and the ultrasonic transmitting unit 40 are disposed on the vertices of a square, respectively.
The shadowless area 41, the shadowless area 42, the shadowless area 43 and the shadowless area 44 respectively have the strongest ultrasonic positioning signals, and can be approximately regarded as that the intelligent terminal only receives the ultrasonic positioning signal service of the ultrasonic transmitting unit above the corresponding area, so that a better accurate positioning effect is realized. For example, in the non-shadow area 41, the ultrasonic positioning signal transmitted by the ultrasonic transmitting unit 10 has the strongest signal, so that the intelligent terminal roaming into the non-shadow area 41 can be regarded as being served by the ultrasonic positioning signal of the ultrasonic transmitting unit 10 only; in the non-shadow area 42, the ultrasonic positioning signal transmitted by the ultrasonic transmitting unit 20 has the strongest signal, so that the intelligent terminal roaming to the non-shadow area 42 can be regarded as being served by the ultrasonic positioning signal of the ultrasonic transmitting unit 20 only; in the non-shadow area 43, the ultrasonic positioning signal transmitted by the ultrasonic transmitting unit 30 has the strongest signal, so that the intelligent terminal roaming to the non-shadow area 43 can be regarded as being served by the ultrasonic positioning signal of the ultrasonic transmitting unit 30 only; in the unshaded region 44, the ultrasound positioning signal transmitted by the ultrasound transmitting unit 40 has the strongest signal, and thus roams to the intelligent terminal in the unshaded region 44, and can be regarded as being served only by the ultrasound positioning signal of the ultrasound transmitting unit 40.
In the unshaded region 41, the unshaded region 42, the unshaded region 43, and the unshaded region 44, a first positioning strategy is performed in which the intensity of the ultrasonic positioning signal emitted by one ultrasonic emission unit is significantly stronger than that of the ultrasonic positioning signals emitted by the other ultrasonic emission units.
In the diagonally shaded areas 51, 52, 53 and 54, there are a plurality of stronger ultrasonic locating signals. In the square hatched area 60, there are a plurality of weak positioning signals mashed. In the diagonally shaded areas 51, 52, 53, 54 and 60, there is much disturbance, and the positioning effect is generally poor. For this reason, the embodiment of the present invention performs the second positioning strategy in which at least two ultrasound transmitting units transmit strong ultrasound positioning signals in the diagonally shaded area 51, diagonally shaded area 52, diagonally shaded area 53, diagonally shaded area 54.
In the square hatched area 60, a third localization strategy is performed in which weak ultrasound localization signals emitted by a plurality of ultrasound emitting units are mashed with each other. When the intelligent terminal roams into the networking environment of the ultrasonic emission unit, the intelligent terminal determines to adopt a first positioning strategy, a second positioning strategy or a third positioning strategy based on the intensity of the received ultrasonic positioning signal. Because the frequency calibration signal has better reference value and detection range than the primary ultrasonic positioning signal and the secondary ultrasonic positioning signal, the frequency calibration signal is preferably adopted as a signal basis for determining whether to adopt a first positioning strategy, a second positioning strategy or a third positioning strategy.
Assume that the sampling points of the frequency calibration signal are N, A f,1 、A f,2 、......、A f,k The amplitude of the frequency calibration signal collected for each sampling point represents the magnitude of the energy of the frequency calibration signal collected for each sampling point in dB.
Region judgment conditions:
wherein,is A f,i Average value of>Is A f,j Average value of (2); if the conditions are metThe signal strengths of the two ultrasound transmitting units are considered to be equivalent; conversely, the signal strength of one ultrasound transmission unit is considered to be significantly greater than the signal strength of the other ultrasound transmission unit, at which point the intelligent terminal is determined to be closer to the transmitter of the stronger frequency calibration signal.
The intelligent terminal calculates the average amplitude of the received frequency calibration signalAnd compared. When no j signal meets the judgment condition for any i signal, namely the intelligent terminal is in the non-shadow area 41, the non-shadow area 42, the non-shadow area 43 or the non-shadow area 44, the first positioning strategy is adopted; when only one pair of i and j meets the judging condition, the intelligent terminal is in the diagonal shadow area 51, the diagonal shadow area 52, the diagonal shadow area 53 and the diagonal shadow area 54, so that the second positioning strategy is adopted; when there are 3 j signals for any i signal that satisfy the above-mentioned area judgment condition, that is, the signal strengths are equivalent, the intelligent terminal is in the square hatched area 60, and thus it is determined that the third positioning strategy is adopted.
The first positioning strategy, the second positioning strategy and the third positioning strategy are described in detail below, respectively.
1. First positioning strategy:
in the unshaded region 41, the unshaded region 42, the unshaded region 43, and the unshaded region 44, the judgment condition that the intensity of the ultrasonic positioning signal transmitted by one ultrasonic transmitting unit is significantly stronger than that of the ultrasonic positioning signals transmitted by the other ultrasonic transmitting units is satisfied, respectively, so that the first positioning strategy is performed in the unshaded region 41, the unshaded region 42, the unshaded region 43, and the unshaded region 44.
In the unshaded region 41, the unshaded region 42, the unshaded region 43 and the unshaded region 44, since the installation height of the ultrasonic transmitting units is far greater than the distance between the main ultrasonic transmitter and the subsonic transmitter, the doppler shifts generated by the motion state of the intelligent terminal relative to the ultrasonic transmitting units are very close, and it can be assumed that the doppler shifts of the ultrasonic positioning signals received by the intelligent terminal are equal.
Step one: the intelligent terminal calculates the average amplitude of the received frequency calibration signalAnd compared. When no j signal meets the judgment condition for any i signal>i≠j,i∈[1,k],j∈[1,k]Namely, the intelligent terminal is arranged in an unshaded area 41, an unshaded area 42, an unshaded area 43 and an unshaded area 44.
Step two: estimating Doppler frequency offset F of each main ultrasonic positioning signal by using phase-locked loop PLL (phase lock loop) D,0,k The frequency offset correction can be carried out on the original main ultrasonic positioning signal and the secondary ultrasonic positioning signal, wherein k represents the kth ultrasonic transmitting unit;
step three: based on the CDMA communication principle, obtaining the time of the ultrasonic positioning signal after frequency offset correction reaching the intelligent terminal;
step four: based on the TDOA positioning principle, accurate positioning of the intelligent terminal is achieved.
The first positioning strategy is described below by way of example.
It is assumed that in fig. 5, in an unshaded region 41 in the upper left corner, the 1 st ultrasound transmitting unit (i.e., the ultrasound transmitting unit 10) is arranged, in an unshaded region 42 in the upper right corner, the 2 nd ultrasound transmitting unit (i.e., the ultrasound transmitting unit 20) is arranged, in an unshaded region 43 in the lower left corner, the 3 rd ultrasound transmitting unit (i.e., the ultrasound transmitting unit 30) is arranged, and in an unshaded region 44 in the lower right corner, the 4 th ultrasound transmitting unit (i.e., the ultrasound transmitting unit 40) is arranged.
Assuming that the intelligent terminal is in the upper left unshaded region 41, the intelligent terminal receives the ultrasonic locating signal and the frequency calibration signal of the 1 st ultrasonic transmitting unit and the adjacent ultrasonic transmitting units around the 1 st ultrasonic transmitting unit.
Step one: the intelligent terminal calculates each receivedAverage amplitude of frequency calibration signalFinding the frequency calibration signal emitted by the ultrasound emitting unit 10 +.>The average amplitude of the frequency calibration signal transmitted by the other ultrasound transmitting unit is much larger than the average amplitude of the frequency calibration signal transmitted by the other ultrasound transmitting unit, then the intelligent terminal is in the upper left-hand unshaded region 41 and decides to employ the first positioning strategy.
Step two: the intelligent terminal estimates the doppler frequency offset F of the main ultrasonic positioning signal of the ultrasonic transmitting unit 10 (i.e., 1 st ultrasonic transmitting unit, k=1) by using the phase-locked loop PLL (phase lock loop) D,0,1 。
Step three: at this time, the frequency shift of the main ultrasonic positioning signal and the sub ultrasonic positioning signal of the 1 st ultrasonic transmitting unit is equal, namely F D,0,1 ≈F D,1,1 ≈F D,2,1 ≈F D,3,1 ≈F D,4,1 Thus apply F D,0,1 The frequency offset of all ultrasonic positioning signals (including main ultrasonic positioning signals and secondary ultrasonic positioning signals) of the 1 st ultrasonic transmitting unit is corrected.
Step four: the intelligent terminal analyzes the ID of the transmitting unit based on the CDMA technology, and calculates the main positioning signal after the frequency offset correctionDelay time t to reach intelligent terminal 0 ；
Step five: the intelligent terminal calculates secondary positioning signals after correction of each frequency offset based on the ID of the transmitting unit and the CDMA technologySelecting three corrected secondary positioning signals with the maximum SNR as a first positioning signal, a second positioning signal and a third positioning signal respectively;
Step six: the intelligent terminal calculates first delay time t of reaching the intelligent terminal of the first positioning signal based on the CDMA technology 1 Second delay time t for second positioning signal to reach intelligent terminal 2 Third delay time t for third positioning signal to reach intelligent terminal 3 ；
Step seven: the intelligent terminal obtains relative coordinates (x) of a first ultrasonic transmitter for transmitting a first positioning signal to the cloud based on the transmitting unit ID 1 ,y 1 ,z 1 ) Relative coordinates (x) of the second ultrasonic transmitter transmitting the second positioning signal 2 ,y 2 ,z 2 ) Third ultrasonic emitter relative coordinates (x) 3 ,y 3 ,z 3 ) And a primary ultrasound transmitter relative coordinate (x 0 ,y 0 ,z 0 ) The method comprises the steps of carrying out a first treatment on the surface of the Based on the respective delay times t 0 ,t 1 ,t 2 ,t 3 And the respective relative coordinates (x 0 ,y 0 ,z 0 )、(x 1 ,y 1 ,z 1 )、(x 2 ,y 2 ,z 2 )、(x 3 ,y 3 ,z 3 ) Calculating relative coordinates (x) of intelligent terminal by using TDOA algorithm c ,y c ,z c ). The intelligent terminal will have relative coordinates (x c ,y c ,z c ) And sending the relative coordinates to a cloud terminal, and enabling the cloud terminal to correspond the relative coordinates to an indoor map and share the relative map to an intelligent terminal in an indoor environment.
2. Second positioning strategy:
in the diagonally shaded areas 51, 52, 53, 54, the judgment conditions for the at least two ultrasound transmitting units to transmit the strong ultrasound positioning signal are satisfied, respectively, and thus the second positioning strategy is executed. In the diagonally shaded areas 51, 52, 53, 54, there are a plurality of strong positioning signal interferences.
Step one: the intelligent terminal calculates the average amplitude of the received frequency calibration signalOnly a pair of i and j meets the judgment condition +.>i≠j,i∈[1,k],j∈[1,k]The intelligent terminal is in a diagonally shaded area 51, a diagonally shaded area 52, a diagonally shaded area 53, a diagonally shaded area 54.
Step two: at this time, the phase-locked loop PLL (phase lock loop) is used to calculate the frequency calibration signal S f,k Doppler frequency offset F of (2) D,f,k Wherein k represents a kth ultrasound transmitting unit;
step three: based on Doppler frequency offset F D,f,k Calculating Doppler frequency offset F of ultrasonic positioning signals D,0,k ；
Wherein F is C,0,k For ultrasonic locating signal S 0,k 、S 1,k …S 4,k Is a center frequency of (a); f (F) C,f,k For the frequency calibration signal S f,k Is a center frequency of (a);
step four: performing frequency offset correction on the corresponding ultrasonic positioning signals;
step five: the intelligent terminal respectively estimates the signal-to-noise ratio of the main ultrasonic positioning signals after the correction of each frequency offset based on the CDMA technology, and selects a group of positioning signals with larger signal-to-noise ratio;
step six: based on the CDMA communication principle, the time for the ultrasonic positioning signal after frequency offset correction to reach the intelligent terminal is obtained, and based on the TDOA positioning principle, the accurate positioning of the intelligent terminal is realized.
The second positioning strategy is illustrated by way of example below.
Assuming the intelligent terminal is in the diagonally shaded area 52, the ultrasonic locating signal and the frequency calibration signal of the surrounding ultrasonic transmitting units will be received.
Step one: the intelligent terminal calculates the average amplitude of the received frequency calibration signalIn which there are only two frequency calibration signals S f,1 、S f,2 Meets the condition of->It is determined that the intelligent terminal is in the diagonally shaded region 52 and a decision is made to employ a second positioning strategy.
Step two: the ultrasonic positioning signals of the 1 st ultrasonic transmitting unit and the 2 nd ultrasonic transmitting unit have similar strength and are obviously larger than those of the other ultrasonic transmitting units, and the intelligent terminal calculates the frequency calibration signals S of the 1 st ultrasonic transmitting unit and the 2 nd ultrasonic transmitting unit by using a phase-locked loop PLL (phaselock loop) f,1 、S f,2 Is the respective Doppler frequency offset F D,f,1 、F D,f,2 。
Step three: frequency calibration signal S based on 1 st and 2 nd ultrasonic transmitting units f,1 、S f,2 Is the respective Doppler frequency offset F D,f,1 、F D,f,2 Intelligent terminal application formulaCalculating Doppler frequency offset F of main ultrasonic positioning signals of the 1 st and 2 nd ultrasonic transmitting units respectively D,0,1 、F D,0,2 。
Step four: doppler frequency offset F of main ultrasonic positioning signal of intelligent terminal based on 1 st ultrasonic transmitting unit D,0,1 Performing frequency offset correction on the main ultrasonic positioning signals and the secondary ultrasonic positioning signals of the 1 st ultrasonic transmitting unit; doppler frequency offset F of main ultrasonic positioning signal of intelligent terminal based on 2 nd ultrasonic transmitting unit D,0,2 And carrying out frequency offset correction on the main ultrasonic positioning signals and the secondary ultrasonic positioning signals of the 2 nd ultrasonic transmitting unit.
Step five: the intelligent terminal analyzes the ID of the transmitting unit based on the CDMA technology, and calculates the main positioning signal after correction of each frequency offsetSelecting a group of positioning signals with larger signal-to-noise ratio (SNR) of the respective SNR; assume positioning signal +.>Is greater than +.>And selecting the 1 st ultrasonic transmitting unit to perform position calculation on the intelligent terminal.
Step six: the intelligent terminal calculates the main positioning signal after the frequency offset correction based on the CDMA technologyDelay time t to reach intelligent terminal 0 。
Step seven: the intelligent terminal calculates secondary positioning signals after correction of each frequency offset based on the ID of the transmitting unit and the CDMA technologyThree corrected secondary positioning signals with the largest SNR are selected as a first positioning signal, a second positioning signal and a third positioning signal.
Step eight: the intelligent terminal calculates first delay time t of reaching the intelligent terminal of the first positioning signal based on the CDMA technology 1 Second delay time t for second positioning signal to reach intelligent terminal 2 Third delay time t for third positioning signal to reach intelligent terminal 3 。
Step nine: the intelligent terminal obtains relative coordinates (x) of a first ultrasonic transmitter for transmitting a first positioning signal to the cloud based on the transmitting unit ID 1 ,y 1 ,z 1 ) Relative coordinates (x) of the second ultrasonic transmitter transmitting the second positioning signal 2 ,y 2 ,z 2 ) Third ultrasonic emitter relative coordinates (x) 3 ,y 3 ,z 3 ) And a primary ultrasound transmitter relative coordinate (x 0 ,y 0 ,z 0 ) The method comprises the steps of carrying out a first treatment on the surface of the Based on the respective delay times t 0 ,t 1 ,t 2 ,t 3 And the respective relative coordinates (x 0 ,y 0 ,z 0 )、(x 1 ,y 1 ,z 1 )、(x 2 ,y 2 ,z 2 )、(x 3 ,y 3 ,z 3 ) Calculating relative coordinates (x) of intelligent terminal by using TDOA algorithm c ,y c ,z c ). The intelligent terminal will have relative coordinates (x c ,y c ,z c ) And sending the relative coordinates to a cloud terminal, and enabling the cloud terminal to correspond the relative coordinates to an indoor map and share the relative map to an intelligent terminal in an indoor environment.
3. Third positioning strategy:
in the square hatched area 60, a third localization strategy is performed in which weak ultrasound localization signals emitted by a plurality of ultrasound emitting units are mashed with each other. The square hatched area 60 is a complex environment where there are multiple weak positioning SIGNAL interferences, the SIGNAL-to-NOISE RATIO SNR (SIGNAL-NOISE RATIO) of each ultrasonic positioning SIGNAL is low, there are many errors, and the estimated SIGNAL arrival time using CDMA techniques produces a large error. In an embodiment of the invention, an ultrasonic emission group is created and positioned by using a super-resolution method through the existing ultrasonic positioning system equipment.
Step one: the intelligent terminal calculates the average amplitude of the received frequency calibration signal And compared. When there are 3 j signals satisfying the above region judgment condition +.>i≠j,i∈[1,k],j∈[1,k]I.e., the signal strengths are comparable, the intelligent terminal is in the square shaded area 60 and determines that a third positioning strategy is to be employed.
Step two, at this time, the phase-locked loop PLL (phase lock loop) is used to calculate the frequency calibration signal S f,k Doppler frequency offset F of (2) D,f,k Wherein k represents a kth ultrasound transmitting unit;
step three: for the corresponding frequency calibration signal S f,k And carrying out frequency offset correction.
Step four: an ultrasound emission set is created. The ultrasonic transmitting group consists of frequency calibration signal transmitters of 4 ultrasonic transmitting units shown in figure 1, and the positioning signals of the ultrasonic transmitting group are frequency calibration signals after frequency offset correction
Step five: estimating the arrival time of the positioning signals of the ultrasonic emission group at the intelligent terminal by using a super-resolution method, such as a MUSIC-CC method (multiple signal classification algorithm, multiple Signal classification-Cross Correlation);
step six: based on the TDOA positioning principle, accurate positioning of the intelligent terminal is achieved.
The third positioning strategy is described below by way of example.
The smart terminal is assumed to be in the square shaded area 60. The intelligent terminal can receive all ultrasonic positioning signals and frequency calibration signals of the 1 st, 2 nd, 3 rd and 4 th ultrasonic transmitting units, but the signal intensity is very low.
Step one: the intelligent terminal calculates the average amplitude of the received frequency calibration signalAnd compared. With four frequency-calibrating signals S f,1 、S f,2 、S f,3 、S f,4 Meets the judgment condition, and is added with->i≠j,i∈[1,4],j∈[1,4]The signal strengths are comparable, the intelligent terminal is in the square shaded area 60 and determines that a third positioning strategy is to be employed.
Step two: at this time, the intelligent terminal calculates the frequency calibration signal S by using the phase-locked loop PLL (phase lock loop) f,1 、S f,2 、S f,3 、S f,4 Doppler frequency offset F of (2) D,f,1 、F D,f,2 、F D,f,3 、F D,f,4 The method comprises the steps of carrying out a first treatment on the surface of the Step three: frequency offset correction is carried out on the frequency calibration signals of the 1 st, 2 nd, 3 rd and 4 th ultrasonic transmitting units;
step four: an ultrasound emission set is created. The ultrasonic transmitting group consists of frequency calibration signal transmitters of the 1 st, 2 nd, 3 rd and 4 th ultrasonic transmitting units, and the positioning signals of the ultrasonic transmitting group are frequency calibration after frequency offset correctionSignal signal
Step five: the intelligent terminal estimates the first positioning signals based on MUSIC-CC super-resolution algorithmFirst delay time t to reach intelligent terminal 1 Second positioning signal->Second delay time t to reach intelligent terminal 2 A third positioning signalThird delay time t to reach intelligent terminal 3 Fourth positioning signal->Third delay time t to reach intelligent terminal 4 ；
Step six: the intelligent terminal obtains relative coordinates (x 1 ,y 1 ,z 1 ) Relative coordinates (x) of the second primary ultrasound transmitter transmitting the second positioning signal 2 ,y 2 ,z 2 ) A third primary ultrasound transmitter relative coordinate (x 3 ,y 3 ,z 3 ) And a fourth primary ultrasound transmitter relative coordinate (x 4 ,y 4 ,z 4 ) The method comprises the steps of carrying out a first treatment on the surface of the Based on the respective delay times t 1 、t 2 、t 3 、t 4 And the respective relative coordinates (x 1 ,y 1 ,z 1 )、(x 2 ,y 2 ,z 2 )、(x 3 ,y 3 ,z 3 )、(x 4 ,y 4 ,z 4 ) Calculating relative coordinates (x) of the intelligent terminal using TDOA algorithm c ,y c ,z c ). The intelligent terminal will have relative coordinates (x c ,y c ,z c ) Is sent to the cloudThe cloud corresponds the relative coordinates to the indoor map, and the relative map is shared to the intelligent terminal in the indoor environment.
Based on the above description, the embodiment of the invention also provides an ultrasonic positioning method. The method is applied to an ultrasonic positioning system, and the ultrasonic positioning system comprises: a plurality of ultrasonic transmitting units and intelligent terminals arranged at respective fixed positions; the method comprises the following steps: enabling the intelligent terminal to compare the intensity of ultrasonic positioning signals received from each ultrasonic transmitting unit; enabling the intelligent terminal to determine to execute one of the following positioning strategies based on the comparison result: the intensity of the ultrasonic positioning signals transmitted by one ultrasonic transmitting unit is obviously stronger than that of the ultrasonic positioning signals transmitted by other ultrasonic transmitting units; a second positioning strategy that at least two ultrasonic transmitting units transmit strong ultrasonic positioning signals; and a third positioning strategy that weak ultrasonic positioning signals transmitted by at least two ultrasonic transmitting units are mutually mixed. In one embodiment, the number of ultrasound transmitting units is 4, and the arrangement points of the 4 ultrasound transmitting units constitute a square. Preferably, the ultrasonic positioning signals include a primary ultrasonic positioning signal, a secondary ultrasonic positioning signal and a frequency calibration signal; the ultrasonic transmitting unit comprises a main transmitting module, a secondary transmitting module and a controller; wherein the main transmitting module comprises a main ultrasonic transmitter and a frequency calibration signal transmitter; the secondary transmitting module comprises at least three secondary ultrasonic transmitters; a primary ultrasound emitter arranged in the geometric center of the at least three secondary ultrasound emitters, a frequency calibration signal emitter arranged at the periphery of the primary ultrasound emitter; the main ultrasonic transmitter is used for transmitting the main ultrasonic positioning signal; the frequency calibration signal transmitter is used for transmitting the frequency calibration signal; the subsonic transmitter is used for transmitting the subsonic positioning signal; the controller is used for controlling the main ultrasonic transmitter, the frequency calibration signal transmitter and the secondary ultrasonic transmitter to transmit simultaneously according to a preset frequency.
Fig. 6 is a flow chart of a first positioning strategy according to the present invention. As shown in fig. 6, the method includes: step 601: calculating Doppler frequency offset of the main ultrasonic positioning signals transmitted by the ultrasonic transmitting units which are obviously stronger than the intensity of other ultrasonic positioning signals; step 602: performing frequency offset correction on the main ultrasonic positioning signals and the secondary ultrasonic positioning signals which are transmitted by the ultrasonic transmitting units and are obviously stronger than other ultrasonic positioning signals by utilizing the Doppler frequency offset; step 603: from the sub-ultrasonic positioning signals subjected to frequency offset correction, three sub-ultrasonic positioning signals are selected according to the sequence of the signal to noise ratio from large to small; step 604: and calculating the coordinates of the intelligent terminal based on the main ultrasonic positioning signal subjected to frequency offset correction and the selected three sub-ultrasonic positioning signals.
Fig. 7 is a flow chart of a second positioning strategy according to the present invention.
As shown in fig. 7, the method includes: step 701: calculating respective Doppler frequency offsets of frequency calibration signals transmitted by at least two ultrasonic transmitting units transmitting strong ultrasonic positioning signals; step 702: respectively carrying out frequency offset correction on the main ultrasonic positioning signals and the sub-ultrasonic positioning signals transmitted by the at least two ultrasonic transmitting units by using respective Doppler frequency offsets; step 703: comparing the signal to noise ratios of the main ultrasonic positioning signals of the at least two ultrasonic transmitting units after the frequency offset correction, and selecting the ultrasonic transmitting unit corresponding to the main ultrasonic positioning signal with the maximum signal to noise ratio as a target ultrasonic transmitting unit; step 704: from the subsonic positioning signals subjected to frequency offset correction of the target ultrasonic transmitting unit, three subsonic positioning signals are selected according to the sequence from the high signal to noise ratio; step 705: and calculating the coordinates of the intelligent terminal based on the main ultrasonic positioning signals and the three selected sub-ultrasonic positioning signals after the frequency offset correction of the target ultrasonic transmitting unit.
Fig. 8 is a flow chart of a third positioning strategy according to the present application. As shown in fig. 8, the method includes:
step 801: calculating respective Doppler frequency offsets of the frequency calibration signals transmitted by all the ultrasonic transmitting units; step 802: respectively carrying out frequency offset correction on the frequency calibration signals transmitted by all the ultrasonic transmitting units by utilizing the Doppler frequency offsets; step 803: and calculating the coordinates of the intelligent terminal based on the frequency calibration signals transmitted by all the ultrasonic transmitting units after the frequency offset correction.
The embodiment of the application also provides an ultrasonic positioning device, which comprises a processor, a memory and a computer program stored on the memory and capable of running on the processor, wherein the computer program realizes the steps of the ultrasonic positioning method when being executed by the processor. It should be noted that not all the steps and modules in the above processes and the structure diagrams are necessary, and some steps or modules may be omitted according to actual needs. The execution sequence of the steps is not fixed and can be adjusted as required. The division of the modules is merely for convenience of description and the division of functions adopted in the embodiments, and in actual implementation, one module may be implemented by a plurality of modules, and functions of a plurality of modules may be implemented by the same module, and the modules may be located in the same device or different devices. The hardware modules in the various embodiments may be implemented mechanically or electronically. For example, a hardware module may include specially designed permanent circuits or logic devices (e.g., special purpose processors such as FPGAs or ASICs) for performing certain operations. A hardware module may also include programmable logic devices or circuits (e.g., including a general purpose processor or other programmable processor) temporarily configured by software for performing particular operations. As regards implementation of the hardware modules in a mechanical manner, either by dedicated permanent circuits or by circuits that are temporarily configured (e.g. by software), this may be determined by cost and time considerations. The application also provides a machine-readable storage medium storing instructions for causing a machine to perform the method of the application. Specifically, a system or apparatus provided with a storage medium on which a software program code realizing the functions of any of the above embodiments is stored, and a computer (or CPU or MPU) of the system or apparatus may be caused to read out and execute the program code stored in the storage medium. Further, some or all of the actual operations may be performed by an operating system or the like operating on a computer based on instructions of the program code. The program code read out from the storage medium may also be written into a memory provided in an expansion board inserted into a computer or into a memory provided in an expansion unit connected to the computer, and then, based on instructions of the program code, a CPU or the like mounted on the expansion board or the expansion unit may be caused to perform part or all of actual operations, thereby realizing the functions of any of the above embodiments. Storage medium implementations for providing program code include floppy disks, hard disks, magneto-optical disks, optical disks (e.g., CD-ROMs, CD-R, CD-RWs, DVD-ROMs, DVD-RAMs, DVD-RWs, DVD+RWs), magnetic tapes, non-volatile memory cards, and ROMs. Alternatively, the program code may be downloaded from a server computer or cloud by a communications network. The above list of detailed descriptions is only specific to practical embodiments of the present application, and is not intended to limit the scope of the present application, and all equivalent embodiments or modifications, such as combinations, divisions or repetitions of features, without departing from the technical spirit of the present application are included in the scope of the present application.
The foregoing description is only of the preferred embodiments of the present invention, and is not intended to limit the scope of the present invention. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present invention should be included in the protection scope of the present invention.

Claims (8)

1. A doppler frequency offset estimation system for an ultrasonic positioning signal, comprising:
the ultrasonic transmitting unit comprises a main transmitting module, a secondary transmitting module and a controller; wherein the main transmitting module comprises a main ultrasonic transmitter and a frequency calibration signal transmitter; the secondary transmitting module comprises at least three secondary ultrasonic transmitters; a primary ultrasound emitter arranged in the geometric center of the at least three secondary ultrasound emitters, a frequency calibration signal emitter arranged at the periphery of the primary ultrasound emitter; the main ultrasonic transmitter is used for transmitting a main ultrasonic positioning signal; the frequency calibration signal transmitter is used for transmitting a frequency calibration signal; the subsonic transmitter is used for transmitting subsonic positioning signals; the controller is used for controlling the main ultrasonic transmitter, the frequency calibration signal transmitter and the secondary ultrasonic transmitter to transmit simultaneously according to a preset frequency; wherein the primary and secondary ultrasonic positioning signals are modulated onto a first carrier wave having a first center frequency; modulating a frequency calibration signal onto a second carrier having a second center frequency, the second center frequency being greater than the first center frequency, the first carrier being non-overlapping with the second carrier, the frequency calibration signal being a narrowband signal;
The intelligent terminal is used for receiving the main ultrasonic positioning signal, the sub-ultrasonic positioning signal and the frequency calibration signal transmitted by the ultrasonic transmitting unit, calculating Doppler frequency offset of the frequency calibration signal in a phase-locked loop mode, and calculating Doppler frequency offset of the main ultrasonic positioning signal and the sub-ultrasonic positioning signal based on Doppler frequency offset of the first center frequency, the second center frequency and the frequency calibration signal, wherein the Doppler frequency offset of the main ultrasonic positioning signal is equal to the Doppler frequency offset of the sub-ultrasonic positioning signal;
the intelligent terminal is used for comparing the intensity of the frequency calibration signals received from each ultrasonic transmitting unit, and determining to execute one of the following positioning strategies based on the comparison result: the intensity of the frequency calibration signal transmitted by one ultrasonic transmitting unit is significantly stronger than the first positioning strategy of the intensity of the frequency calibration signals transmitted by other ultrasonic transmitting units; a second positioning strategy in which at least two ultrasound transmitting units transmit strong frequency calibration signals; a third localization strategy in which weak frequency calibration signals transmitted by at least two ultrasound transmitting units are mutually mixed;
the intelligent terminal is used for carrying out frequency offset correction on the main ultrasonic positioning signal and the secondary ultrasonic positioning signal based on Doppler frequency offset of the main ultrasonic positioning signal and the secondary ultrasonic positioning signal, and calculating coordinates of the intelligent terminal based on the main ultrasonic positioning signal after frequency offset correction and the secondary ultrasonic positioning signal after frequency offset correction;
The third positioning strategy comprises: calculating respective Doppler frequency offsets of the frequency calibration signals transmitted by all the ultrasonic transmitting units; respectively carrying out frequency offset correction on the frequency calibration signals transmitted by all the ultrasonic transmitting units by utilizing the Doppler frequency offsets; calculating the coordinates of the intelligent terminal based on the frequency calibration signals transmitted by all ultrasonic transmitting units after frequency offset correction; the calculating the coordinates of the intelligent terminal based on the frequency calibration signals transmitted by all ultrasonic transmitting units after frequency offset correction comprises: creating an ultrasonic emission group, wherein the ultrasonic emission group comprises frequency calibration signal transmitters of all ultrasonic emission units, and positioning signals of the ultrasonic emission group are frequency calibration signals of all ultrasonic emission units after frequency offset correction; respectively estimating delay time of each positioning signal of the ultrasonic emission group reaching the intelligent terminal; acquiring the relative coordinates of each main ultrasonic emitter; and determining the relative coordinates of the intelligent terminal based on the delay time of each positioning signal of the ultrasonic transmitting group reaching the intelligent terminal and the relative coordinates of each main ultrasonic transmitter.
2. The doppler shift estimation system of an ultrasonic positioning signal according to claim 1, wherein the number of the ultrasonic transmitting units is 4, and the arrangement points of the 4 ultrasonic transmitting units constitute a square.
3. The Doppler shift estimation system of claim 1, wherein,
an intelligent terminal for:
determining to execute a first positioning strategy when the difference between the amplitude of the frequency calibration signal transmitted by one ultrasonic transmitting unit and the amplitude of the frequency calibration signal transmitted by an ultrasonic transmitting unit other than the ultrasonic transmitting unit is greater than a predetermined first threshold value; or (b)
Determining to execute a second positioning strategy when the amplitudes of the frequency calibration signals transmitted by the two ultrasonic transmitting units are both greater than a predetermined second threshold value and the difference of the frequency calibration signals transmitted by the two ultrasonic transmitting units is less than a predetermined third threshold value;
and determining to execute the third positioning strategy when the amplitude of the frequency calibration signal transmitted by each ultrasonic transmitting unit is smaller than a preset fourth threshold value or the difference value of the amplitude of the frequency calibration signals transmitted by any two ultrasonic transmitting units is smaller than a preset fifth threshold value.
4. The Doppler frequency offset estimation method for the ultrasonic positioning signals is characterized by being suitable for Doppler frequency offset estimation of the ultrasonic positioning signals transmitted by an ultrasonic transmitting unit, wherein the ultrasonic transmitting unit comprises a main transmitting module, a secondary transmitting module and a controller; wherein the main transmitting module comprises a main ultrasonic transmitter and a frequency calibration signal transmitter; the secondary transmitting module comprises at least three secondary ultrasonic transmitters; a primary ultrasound emitter arranged in the geometric center of the at least three secondary ultrasound emitters, a frequency calibration signal emitter arranged at the periphery of the primary ultrasound emitter; the main ultrasonic transmitter is used for transmitting a main ultrasonic positioning signal; the frequency calibration signal transmitter is used for transmitting a frequency calibration signal; the subsonic transmitter is used for transmitting subsonic positioning signals; the controller is used for controlling the main ultrasonic transmitter, the frequency calibration signal transmitter and the secondary ultrasonic transmitter to transmit simultaneously according to a preset frequency; wherein the primary and secondary ultrasonic positioning signals are modulated onto a first carrier wave having a first center frequency; modulating a frequency calibration signal onto a second carrier having a second center frequency, the second center frequency being greater than the first center frequency, the first carrier being non-overlapping with the second carrier, the frequency calibration signal being a narrowband signal; the method comprises the following steps:
The intelligent terminal receives the main ultrasonic positioning signal, the secondary ultrasonic positioning signal and the frequency calibration signal which are transmitted by the ultrasonic transmitting unit;
the intelligent terminal calculates Doppler frequency offset of the frequency calibration signal in a phase-locked loop mode;
the intelligent terminal calculates Doppler frequency offset of the main ultrasonic positioning signal and the secondary ultrasonic positioning signal based on the Doppler frequency offset of the first center frequency, the second center frequency and the frequency calibration signal, wherein the Doppler frequency offset of the main ultrasonic positioning signal is equal to the Doppler frequency offset of the secondary ultrasonic positioning signal;
wherein the intelligent terminal compares the intensities of the frequency calibration signals received from the respective ultrasonic transmitting units, and based on the comparison result, determines to execute one of the following positioning strategies: the intensity of the frequency calibration signal transmitted by one ultrasonic transmitting unit is significantly stronger than the first positioning strategy of the intensity of the frequency calibration signals transmitted by other ultrasonic transmitting units; a second positioning strategy in which at least two ultrasound transmitting units transmit strong frequency calibration signals; a third localization strategy in which weak frequency calibration signals transmitted by at least two ultrasound transmitting units are mutually mixed;
the intelligent terminal carries out frequency offset correction on the main ultrasonic positioning signal and the secondary ultrasonic positioning signal based on Doppler frequency offset of the main ultrasonic positioning signal and the secondary ultrasonic positioning signal, and calculates coordinates of the intelligent terminal based on the main ultrasonic positioning signal after frequency offset correction and the secondary ultrasonic positioning signal after frequency offset correction;
The third positioning strategy comprises: calculating respective Doppler frequency offsets of the frequency calibration signals transmitted by all the ultrasonic transmitting units; respectively carrying out frequency offset correction on the frequency calibration signals transmitted by all the ultrasonic transmitting units by utilizing the Doppler frequency offsets; calculating the coordinates of the intelligent terminal based on the frequency calibration signals transmitted by all ultrasonic transmitting units after frequency offset correction; the calculating the coordinates of the intelligent terminal based on the frequency calibration signals transmitted by all ultrasonic transmitting units after frequency offset correction comprises: creating an ultrasonic emission group, wherein the ultrasonic emission group comprises frequency calibration signal transmitters of all ultrasonic emission units, and positioning signals of the ultrasonic emission group are frequency calibration signals of all ultrasonic emission units after frequency offset correction; respectively estimating delay time of each positioning signal of the ultrasonic emission group reaching the intelligent terminal; acquiring the relative coordinates of each main ultrasonic emitter; and determining the relative coordinates of the intelligent terminal based on the delay time of each positioning signal of the ultrasonic transmitting group reaching the intelligent terminal and the relative coordinates of each main ultrasonic transmitter.
5. The method for Doppler shift estimation of an ultrasonic positioning signal according to claim 4, wherein,
The bandwidth of the first carrier wave is 3KHz, and the frequency band of the first carrier wave is 17 KHz-20 KHz;
the bandwidth interval of the second carrier is [200Hz,500Hz ].
6. The method for Doppler shift estimation of an ultrasonic positioning signal according to claim 4, wherein,
the number of the second carriers is multiple, and a guard interval is arranged between every two adjacent second carriers, and the bandwidth range of the guard interval is [200Hz,400Hz ].
7. A doppler bias estimation device for an ultrasound positioning signal, comprising a processor, a memory and a computer program stored on the memory and executable on the processor, which when executed by the processor, implements the steps of the doppler bias estimation method for an ultrasound positioning signal according to any one of claims 4 to 6.
8. A computer readable storage medium, wherein a computer program is stored on the computer readable storage medium, which when executed by a processor, implements the steps of the doppler bias estimation method of an ultrasound positioning signal according to any one of claims 4 to 6.
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