CN104602340A

CN104602340A - Positioning system and method based on ultra-wide band technology

Info

Publication number: CN104602340A
Application number: CN201410853898.7A
Authority: CN
Inventors: 熊丹; 丁宁; 吴晖; 于练; 张钦丽
Original assignee: SHENZHEN KESONG ELECTRONIC CO Ltd
Current assignee: SHENZHEN KESONG ELECTRONIC CO Ltd
Priority date: 2014-12-31
Filing date: 2014-12-31
Publication date: 2015-05-06

Abstract

The invention provides a positioning method. The positioning method is characterized by comprising enabling a terminal to be positioned to issue a positioning request; according to the positioning request, obtaining signal transmission data among the terminal to be positioned, a reference tag and multiple base stations; computing the estimated coordinate of the terminal to be positioned according obtained signals, performing multiple iterative convergence on the estimated coordinate to obtain the position coordinate of the terminal to be positioned. The positioning method can effectively improve the positioning precision. The invention also provides a positioning system.

Description

Positioning system and positioning method based on ultra-wideband technology

Technical Field

The present invention relates to the field of wireless communication technologies, and in particular, to a positioning system and a positioning method based on an ultra wideband technology.

Background

With the continuous development of human society, the requirements of people on wireless communication are continuously improved, and emerging wireless network technologies (such as WiFi, ZigBee, bluetooth, and Ultra Wide Band (UWB) technologies) are widely applied in the fields of offices, homes, factories, and the like. The UWB wireless positioning technology has the advantages of low power consumption, good multipath resistance, high security, low system complexity, real-time performance, expandability and the like, has a very high time resolution, can achieve centimeter-level positioning accuracy, has become a hot spot of the future wireless positioning technology, and is considered as one of the key technologies of the next generation of wireless communication.

In the prior art, UWB positioning can be accomplished by ranging and direction finding, and commonly used methods include a time of flight (TOF) method, a Received Signal Strength (RSS) method, an angle of arrival (AOA) method, a time of arrival/time difference of arrival (TOA/TDOA) method, and the like. The ranging method requires that a sending device and a receiving device are always synchronous, and the receiving device provides the transmission time of signals; the TOF method uses clock offsets to solve the synchronization problem; the RSS method depends on a path loss model, has the accuracy related to the node distance, is extremely sensitive to the channel environment and has low robustness; the AOA method needs to measure the arrival angle of the UWB signal, and has high requirements on the base station antenna, thereby increasing the equipment cost in the positioning system; in contrast, the TOA/TDOA method is based on the multipath arrival delay estimation theory, and can most embody the characteristic of high time resolution of the UWB signal. However, using TOA positioning requires that both parties are clock synchronized, so in practical UWB positioning systems, TDOA is a feasible way to locate both parties without clock synchronization, but the positioning method also has the problems of transmission signal delay and base station synchronization requirement.

In the prior art, the delay time of the transmitted signal is difficult to calculate, so the delay time is usually set as a fixed parameter according to an empirical value, but in actual use, due to the influence of environmental factors, temperature, hardware plate making and the like, the actual value of the delay time of the transmitted signal is different, measurement accuracy is inaccurate, and finally positioning deviation occurs; the time between the base stations is not uniform, which causes a large time deviation and further affects the positioning accuracy. In order to realize high-precision positioning, nanosecond-level time unification is required among base stations, and the cost of the base stations is greatly increased.

Disclosure of Invention

The invention aims to provide a positioning system and a positioning method based on an ultra-wideband technology, which are used for solving the technical problems of emission delay and non-uniform time among base stations in the existing positioning system and positioning method.

The embodiment of the invention provides a positioning method, which is characterized by comprising the following steps: a terminal to be positioned sends a positioning request; acquiring signal transmission data among the terminal to be positioned, the reference tag and the base stations according to the positioning request; and calculating the estimated coordinate of the terminal to be positioned according to the acquired signal transmission data, and performing iterative convergence on the estimated coordinate for multiple times to obtain the position coordinate of the terminal to be positioned.

Preferably, the step of acquiring signal transmission data between the terminal to be positioned, the reference tag, and the plurality of base stations according to the positioning request includes: acquiring positioning request data, wherein the positioning request data comprises the arrival time of a first positioning signal transmitted by the terminal to be positioned and the arrival time of a first reference signal used for carrying out time unification on the plurality of base stations receiving the first positioning signal; acquiring positioning assistance data, wherein the positioning assistance data comprises the arrival time of a reference positioning signal transmitted by the reference tag and the arrival time of a second reference signal used for unifying the time of the plurality of base stations receiving the reference positioning signal; and acquiring position information, wherein the position information comprises the reference label and the coordinate information of the plurality of base stations.

Preferably, the step of calculating the estimated coordinates of the terminal to be positioned according to the acquired signal transmission data includes: calculating a time difference of arrival of the first positioning signal and the reference positioning signal; calculating the distance difference between the terminal to be positioned and the plurality of base stations according to the calculated arrival time difference; and calculating the estimated coordinates of the terminal to be positioned by using a Fang algorithm according to the calculated distance difference.

Preferably, the step of calculating the time difference of arrival of the first positioning signal and the reference positioning signal comprises: calculating the time difference of the first positioning signal and the reference positioning signal reaching the kth base station; and respectively calculating the time difference between the arrival of the first positioning signal and the arrival of the reference positioning signal at two base stations in the plurality of base stations.

Preferably, the step of calculating the time difference between the arrival of the first positioning signal and the arrival of the reference positioning signal at two base stations of the plurality of base stations respectively comprises: calculating a first positioning time reference of the plurality of base stations according to the arrival time of the first reference signal, and calculating the time difference of the first positioning signal arriving at two base stations in the plurality of base stations according to the first positioning time reference; and calculating second positioning time references of the plurality of base stations according to the arrival time of the second reference signal, and calculating the time difference of the reference positioning signal arriving at two base stations in the plurality of base stations according to the second positioning time references.

Preferably, the method further comprises the following steps: and acquiring the position coordinates of the terminal to be positioned and the position coordinates of a target point, and controlling the terminal to be positioned to reach the target point.

Preferably, when performing two-dimensional positioning, the number of the plurality of base stations is 3; when three-dimensional positioning is carried out, the number of the base stations is 4

An embodiment of the present invention provides a positioning system, including: the positioning method comprises the following steps that a terminal to be positioned, a reference label, a plurality of base stations and a background server are arranged, wherein the terminal to be positioned comprises the positioning label, and a positioning request is sent out through the positioning label; the background server comprises an acquisition module and a calculation module; the acquisition module is used for acquiring signal transmission data among the terminal to be positioned, the reference tag and the base stations according to the positioning request; the calculation module is used for calculating the estimated coordinates of the terminal to be positioned according to the acquired signal transmission data, performing iterative convergence for multiple times by taking the estimated coordinates as an initial iterative position, and calculating the position coordinates of the terminal to be positioned.

Preferably, the obtaining module includes: a first obtaining unit, configured to obtain positioning request data, where the positioning request data includes arrival time of a first positioning signal transmitted by the terminal to be positioned and arrival time of a first reference signal used for performing time unification on the plurality of base stations that receive the first positioning signal; a second obtaining unit, configured to obtain positioning assistance data, where the positioning assistance data includes an arrival time of a reference positioning signal transmitted by the reference tag and an arrival time of a second reference signal used for time unification of the plurality of base stations that receive the reference positioning signal; a third obtaining unit, configured to obtain location information, where the location information includes the reference tag and coordinate information of the multiple base stations.

Preferably, the calculation module comprises: a first calculation unit for calculating a time difference of arrival of the first positioning signal and the reference positioning signal; a second calculating unit, configured to calculate distance differences between the terminal to be positioned and the base stations according to the calculated time difference of arrival; and the pre-estimation unit is used for calculating the pre-estimated coordinates of the terminal to be positioned by using a Fang algorithm according to the calculated distance difference.

Advantageously, the positioning method and the positioning system of the invention send a reference signal through the main base station, so that the system does not need to start the positioning clock accurately and synchronously, and can obtain the positioning information of the terminal to be positioned only by measuring the time interval between the reference signal and the positioning signal from the terminal to be positioned, thereby effectively improving the positioning precision, and in the actual demonstration, the positioning precision can reach 0.1m by using the positioning method for positioning. In addition, the node arrangement of the positioning method of the present invention includes 1 reference tag in addition to 4 base stations and 1 positioning tag, and such an arrangement can cancel the time delay of transmitting the UWB signal by the antenna of the mobile tag in the calculation. The 1 master base station transmits a reference signal to the 3 slave base stations, and the TDOA (time difference of arrival) is used for effectively avoiding the problem of base station time synchronization in the prior art.

Drawings

In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings used in the description of the embodiments or the prior art will be briefly described below, it is obvious that the drawings in the following description are only some embodiments of the present invention, and for those skilled in the art, other drawings can be obtained according to the drawings without creative efforts.

Fig. 1 is a schematic diagram of a node arrangement of a positioning system according to an embodiment of the present invention.

Fig. 2 is a schematic diagram of processing a delay difference of arrival of a received signal in a positioning system according to an embodiment of the present invention.

Fig. 3 is a specific flowchart of a positioning method according to an embodiment of the present invention.

Fig. 4 is a specific flowchart of a method for calculating estimated coordinates of a terminal to be positioned according to an embodiment of the present invention

Fig. 5 is a schematic structural diagram of a positioning system according to an embodiment of the present invention.

Fig. 6 is a schematic structural diagram of an acquisition module according to an embodiment of the present invention.

Fig. 7 is a schematic structural diagram of a computing module according to an embodiment of the present invention.

Detailed Description

In order to make the objects, technical solutions and advantages of the present invention more apparent, the present invention is described in further detail below with reference to the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are merely illustrative of the invention and are not intended to limit the invention.

Fig. 1 is a schematic diagram of a node arrangement of a positioning system according to an embodiment of the present invention. Fig. 2 is a schematic diagram of processing a delay difference of arrival of a received signal in a positioning system according to an embodiment of the present invention. Specifically, there is a transmission delay when the positioning tag and the reference tag transmit UWB positioning signals through the antenna, and there is a reception delay when each base station receives positioning signals transmitted from the positioning tag and the reference tag through the base station antenna, in order to eliminate the transmission delay, as shown in fig. 1, unlike the conventional node arrangement for performing three-dimensional positioning, in the node arrangement of the positioning system provided according to an embodiment of the present invention, 4 base stations are used to perform three-dimensional positioning on the positioning tag, and 1 reference tag is added, and according to the time difference between the reference tag and the mobile tag reaching the kth base station, the transmission delay τ can be eliminated_k。

In addition, to solve the problem of non-uniform time among base stations, in an embodiment of the present invention, the base stations in the node arrangement are divided into main base stations (e.g., BSs)₁) With slave base stations (e.g. BS)₂、BS₃、BS₄) Master base station BS₁Upon receipt of a location tag transmissionAfter the first positioning signal and the reference positioning signal transmitted by the reference tag, waiting for T₀₁At a time, a first reference signal and a second reference signal are transmitted from the base station BS₂、BS₃、BS₄There is also a time delay D in receiving the reference signal₁₂、D₁₃、D₁₄However, because the positions of the base stations are fixed, time delay can be obtained through calculation, and according to the time difference between the UWB positioning signals emitted by the positioning tags and k base stations, the distance difference between k groups of mobile tags and k base stations can be obtained, so that a hyperboloid intersection model is established to solve the position of the positioning tags.

Fig. 3 is a detailed flowchart of a positioning method 300 according to an embodiment of the invention. As shown in fig. 3, the positioning method 300 includes the following steps.

Step S302: and the terminal to be positioned sends a positioning request.

Step S304: and acquiring signal transmission data among the terminal to be positioned, the reference tag and the plurality of base stations according to the positioning request.

Specifically, in an embodiment of the present invention, first, positioning request data is obtained, where the positioning request data includes an arrival time of a first positioning signal transmitted by a terminal to be positioned and an arrival time of a first reference signal used for unifying time of a plurality of base stations receiving the first positioning signal; then, positioning auxiliary data is obtained, wherein the positioning auxiliary data comprises the arrival time of a reference positioning signal transmitted by a reference tag and the arrival time of a second reference signal used for carrying out time unification on a plurality of base stations receiving the reference positioning signal; and finally, acquiring position information, wherein the position information comprises the reference label and the coordinate information of the plurality of base stations.

Step S306: and calculating the estimated coordinate of the terminal to be positioned according to the acquired signal transmission data, and performing iterative convergence on the estimated coordinate for multiple times to obtain the position coordinate of the terminal to be positioned.

Preferably, this embodiment further includes the steps of:

and acquiring the position coordinates of the terminal to be positioned and the position coordinates of the target point, and controlling the terminal to be positioned to reach the target point.

Preferably, when performing two-dimensional positioning, the number of the plurality of base stations is 3; when three-dimensional positioning is carried out, the number of the plurality of base stations is 4.

Fig. 4 is a flowchart illustrating a method 400 for calculating estimated coordinates of a terminal to be positioned according to an embodiment of the present invention. As shown in fig. 4, the calculation method 400 includes the following steps.

Step S402: a time difference of arrival of the first positioning signal and the reference positioning signal is calculated.

Since there is a certain difference in the time display at the same time in different products (for example, there is a certain deviation between the time of the display of the watch and the time of the display of the computer), there is always a deviation between the time when the positioning terminal transmits the first positioning signal and the time when the reference tag transmits the reference positioning signal and the time when the plurality of base stations display.

Specifically, as shown in connection with fig. 2. Firstly, calculating the time difference of the arrival of a first positioning signal transmitted by a terminal to be positioned and a reference positioning signal transmitted by a reference label at a kth base station. As shown in FIG. 2, t_0kAnd t_1kThe arrival time of a first positioning signal transmitted by a terminal to be positioned and a reference positioning signal transmitted by a reference tag to a kth base station; d_kAnd d_k' is the distance between the terminal to be positioned and the reference tag and the kth base station, T₀And T₁Absolute time, Δ i, at which a first locating signal is transmitted for a terminal to be located and a reference locating signal is transmitted for a reference tag_0kIs the time deviation between the initial time I of the terminal to be positioned and the initial time of the kth base station,. DELTA.i_1kIs the time deviation of the initial time I of the reference label and the initial time of the kth base station, tau_kFor the transmission delay from the radio frequency front end (RF) of the terminal to be positioned and the reference tag to the kth base station, let τ be_kRemain unchanged for a short time (e.g., a few microseconds); then there is

t_0k＝τ_k+d_k/c+(T₀+△i_0k) (1)

t_1k＝τ_k+d_k′/c+(T₁+△i_1k) (2)

△t_k＝t_1k-t_0k＝d_k′/c-d_k/c+△T+△i_1k-△i_0k (3)

Wherein: t is₁-T₀，d_kRepresenting the distance d 'between the terminal to be positioned and the kth base station'_kDenotes the distance, Δ t, of the reference tag from the kth base station_kAnd the time difference between the first positioning signal transmitted by the terminal to be positioned and the arrival of the reference positioning signal transmitted by the reference tag at the kth base station is represented.

Assuming that there are 4 base stations (i.e., k is 4), then for all base stations:

in the formula (1), τ is delayed due to emission_kThe values easily affected by the environment such as temperature are different and the calculation amount is large, and the application of TDOA (time difference of arrival) can eliminate tau_kFor example, as shown in formula (3).

Then, time differences between the arrival of the first positioning signal and the reference positioning signal at two base stations in the plurality of base stations are respectively calculated. Due to the time deviation delta i of the terminal to be positioned, the reference label and the kth base station_0k、△i_1kThe positioning information of the terminal to be positioned can be obtained by measuring the time intervals of the reference signal, the first positioning signal from the terminal to be positioned and the reference positioning signal from the reference label without accurately and synchronously starting the positioning clock. The method comprises the following steps: calculating a first positioning time reference of the plurality of base stations according to the arrival time of the first reference signal, and calculating the time difference of the first positioning signal arriving at two base stations in the plurality of base stations according to the first positioning time reference; and calculating a second positioning time reference of the plurality of base stations according to the arrival time of the second reference signal, and calculating the time difference of the reference positioning signal arriving at two base stations in the plurality of base stations through the second positioning time reference.

Specifically, the signal processing procedure of the plurality of base stations is as shown in fig. 2, wherein the dark color is UWB transmission signal and the colorless color is UWB reception signal。t₀₁、t₀₂、t₀₃、t₀₄The arrival times t of the first positioning signals respectively transmitted by the terminal to be positioned at the plurality of base stations₁₁、t₁₂、t₁₃、t₁₄The arrival times of the reference positioning signals respectively transmitted by the reference tags to the plurality of base stations; waiting for T to ensure that a plurality of base stations receive the first positioning signal transmitted by the terminal to be positioned and the reference positioning signal transmitted by the reference label₀₁After (being a fixed value), the master base station BS₁Transmitting a first reference signal and a second reference signal to a slave base station BS, respectively₂From the base station BS₃From the base station BS₄；S₂、S'₂、S₃、S’₃、S₄、S'₄Are respectively from the main base station BS₁Arrives at the slave base station BS₂From the base station BS₃From the base station BS₄The arrival time of (c); d₁₂、D₁₃、D₁₄Is a main base station BS₁And slave base station BS₂From the base station BS₃From the base station BS₄Wherein the time delay D is due to the fixed position between the base stations₁₂、D₁₃、D₁₄Is calculable. With a master base station BS₁Receiving a first positioning signal transmitted by a terminal to be positioned, for example, a main base station BS₁Wait for T₀₁Transmitting a first reference signal, as indicated by the dashed box in fig. 2, (S)₂-D₁₂) For the slave base station BS₂(ii) a positioning time reference of (S)₃-D₁₃) For the slave base station BS₃(ii) a positioning time reference of (S)₄-D₁₄) For the slave base station BS₄The positioning time reference of (2).

Therefore, in the whole positioning system, the plurality of base stations use the arrival time of the first reference signal as the timing starting time, and the time difference between the arrival of the first positioning signal transmitted by the terminal to be positioned and the plurality of base stations can be accurately calculated. Due to the fact that

T₀₂＝S₂-D₁₂-t₀₂，T₀₃＝S₃-D₁₃-t₀₃，T₀₄＝S₄-D₁₄-t₀₄Then, the TDOA values between the terminal to be located and the base stations are calculated as follows:

T₂₁＝T₀₁-T₀₂＝T₀₁-(S₂-D₁₂-t₀₂) (5)

T₃₁＝T₀₁-T₀₃＝T₀₁-(S₃-D₁₃-t₀₃) (6)

T₄₁＝T₀₁-T₀₄＝T₀₁-(S₄-D₁₄-t₀₄) (7)

wherein, T_xyThe time difference between a first positioning signal transmitted by a terminal to be positioned to a base station X and a first positioning signal transmitted by a terminal to be positioned to a base station Y is shown, and the same principle can be known as T'_xyThe time difference between the reference positioning signal transmitted by the reference tag to base station X and to base station Y is:

T′₂₁＝T₀₁-T′₀₂＝T₀₁-(S′₂-D′₁₂-t₁₂) (8)

T′₃₁＝T₀₁-T′₀₃＝T₀₁-(S′₃-D′₁₃-t₁₃) (9)

T′₄₁＝T₀₁-T′₀₄＝T₀₁-(S′₄-D′₁₄-t₁₄) (10)

step S404: and calculating the distance difference between the terminal to be positioned and the plurality of base stations according to the calculated arrival time difference.

Specifically, equation (4) can be derived from the TDOA location algorithm:

according to fig. 2, equation (11) can be converted into:

the distance difference formula can be obtained by substituting equation (12) with equation (5) to equation (10) above, and is:

d₂-d₁＝(d₂′-d₁′)-c((S₂-D₁₂-t₀₂)-(S′₂-D′₁₂-t₁₂))

d₃-d₁＝(d₃′-d₁′)-c((S₃-D₁₃-t₀₃)-(S′₃-D′₁₃-t₁₃)) (13)

d₄-d₁＝(d₄′-d₁′)-c((S₄-D₁₄-t₀₄)-(S′₄-D′₁₄-t₁₄))

wherein c is 3 × 10⁸m/s。

Step S406: and calculating the estimated coordinates of the terminal to be positioned by using a Fang algorithm according to the calculated distance difference.

In an embodiment of the invention, specifically, a three-dimensional coordinate system is first established, with the xoy plane parallel to the horizontal plane. The Oz axis is directed vertically upward from the xoy plane. Assuming that the initial position coordinates of the terminal to be positioned are (x, y, z), the coordinates of the reference tag are (x ', y', z '), and the coordinates of the plurality of base stations are (x', y ', z')_i,y_i,z_i) (i ═ 1,2,3,4), then can be obtained from formula (13):

wherein, the distance between the terminal to be positioned and the plurality of base stations is d_i(i ═ 1,2,3, 4). Terminal to be positioned and slave base station (slave base station BS)₂From the base station BS₃From the base station BS₄) Distance between terminal to be positioned and main base station BS₁Has a difference of d_i,1. A schematic diagram of the positioning of a terminal to be positioned is shown in fig. 1. The following relation exists according to the time difference positioning principle:

(x-x_i)²+(y-y_i)²+(z-z_i)²＝d_i ² (15)

d_i,1＝d_i-d₁ (16)

wherein d is_i,1Indicating the terminal to be positioned and the slave base station (slave base station BS)₂From the base station BS₃From the base station BS₄) Distance between terminal to be positioned and main base station BS₁C is 3 × 10⁸m/s。

Order toFrom equation (15), it can be seen that

d_{i}^{2} = k_{i} - 2 x_{i} x - 2 y_{i} y - 2 z_{i} z + x^{2} + y^{2} + z^{2} - - - (17)

According to the distance difference d measured in step S404_i,1And estimating the coordinate value of the node in the terminal to be positioned by using the Fang algorithm. The specific method comprises the following steps:

let i equal to 1, available

d_{1}^{2} = k_{1} - 2 x_{1} x - 2 y_{1} y - 2 z_{1} z + x^{2} + y^{2} + z^{2} - - - (18)

According to the formulae (17), (18) and (16),

d_{i, 1}^{2} + 2 d_{i, 1} d_{1} = d_{i}^{2} - d_{1}^{2} = k_{i} - 2 x_{i, 1} x - 2 y_{i, 1} y - 2 z_{i, 1} z - k_{1} - - - (19)

wherein x is_i,1＝x_i-x₁，y_i,1＝y_i-y₁，z_i,1＝z_i-z₁When x, y, and z are regarded as unknown numbers, equation (19) becomes a linear equation system. And solving the values of x, y and z to obtain the position coordinates of the terminal to be positioned. Setting a main base station BS₁Is (0, 0, 0), from the base station BS₂From the base station BS₃From the base station BS₄Are respectively (x)₂,0,0)、(x₃,y₃,0)、(x₄,y₄,z₄) Then, thenFrom the formula (19)

\{\begin{matrix} - d_{2,1} d_{1} = d_{2,1}^{2} - x_{2}^{2} + 2 x_{2} x \\ - 2 d_{3,1} d_{1} = d_{3,1}^{2} - (x_{3}^{2} + y_{3}^{2}) + 2 (x_{3} x + y_{3} y) \\ - 2 d_{4,1} d_{1} = d_{4,1}^{2} - (x_{4}^{2} + y_{4}^{2} + z_{4}^{2}) + 2 (x_{4} x + y_{4} y + z_{4} z) \end{matrix} - - - (20)

Elimination of d of formula (20)₁The following results were obtained:

y＝g×x+h (21)

z＝k×x+l (22)

wherein:

g＝((d_3,1x₂)/d_2,1-x₃)/y₃

h = (x_{3}^{2} + y_{3}^{2} - d_{3,1}^{2} + d_{3,1} d_{2,1} (1 - {(x_{2} / d_{2,1})}^{2})) / 2 y_{3}

k＝(d_4,1x₂y₃-d_2,1x₄y₃-d_3,1x₂y₄+d_3,1x₃y₄)/(d_2,1y₃z₄)

l = \frac{d_{4,1} y_{3} d_{2,1}^{2} - d_{4,1} y_{3} x_{2}^{2} - d_{2,1} y_{3} d_{4,1}^{2} + d_{2,1} y_{3} (x_{4}^{2} + y_{4}^{2} + z_{4}^{2}) - d_{3,1} y_{4} (d_{2,1}^{2} - x_{2}^{2}) - d_{2,1} y_{4} (x_{3}^{2} + y_{3}^{2} + d_{3,1}^{2})}{2 d_{2,1} y_{3} z_{4}}

the formula (21) and the formula (22) may be substituted for the formula (1) in the formula (20):

d×x²+e×x+f＝0 (23)

wherein:

d = 4 d_{2,1}^{2} + 4 d_{2,1}^{2} g^{2} + 4 d_{2,1}^{2} k^{2} - 4 x_{2}^{2}

e = 8 d_{2,1}^{2} gh + 8 d_{2,1}^{2} lk - 4 x_{2} (d_{2,1}^{2} - x_{2}^{2})

f = 4 d_{2,1}^{2} h^{2} + 4 d_{2,1}^{2} l^{2} - {(d_{2,1}^{2} - x_{2}^{2})}^{2}

solving a quadratic equation with one element can solve x, and can solve y and z in the same way. Thereby obtaining the positioning coordinates (x, y, z) of the terminal to be positioned.

Finally, in order to further improve the positioning accuracy, the positioning result obtained by the equation (23) is used as the estimated positionAnd performing initial iteration, wherein the iteration direction of each step is along the direction of descending of the current point function value. Converting a positioning model of the terminal to be positioned into:

η＝h_t-g_t (24)

wherein,

which is indicative of the error in the position estimate,

representing the difference between the true value of the distance difference and the measured value,

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<mi>z</mi> </mrow> </mfrac> <mo>|</mo> </mrow> <mrow> <mo>(</mo> <mover> <mi>x</mi> <mi>Λ</mi> </mover> <mo>,</mo> <mover> <mi>y</mi> <mi>Λ</mi> </mover> <mo>,</mo> <mover> <mi>z</mi> <mi>Λ</mi> </mover> <mo>)</mo> </mrow> </msub> </mtd> </mtr> <mtr> <mtd> <msub> <mrow> <mfrac> <mrow> <mo>&PartialD;</mo> <mi>Δ</mi> <msub> <mi>d</mi> <mn>2</mn> </msub> </mrow> <mrow> <mo>&PartialD;</mo> <mi>x</mi> </mrow> </mfrac> <mo>|</mo> </mrow> <mrow> <mo>(</mo> <mover> <mi>x</mi> <mi>Λ</mi> </mover> <mo>,</mo> <mover> <mi>y</mi> <mi>Λ</mi> </mover> <mo>,</mo> <mover> <mi>z</mi> <mi>Λ</mi> </mover> <mo>)</mo> </mrow> </msub> </mtd> <mtd> <msub> <mrow> <mfrac> <mrow> <mo>&PartialD;</mo> <mi>Δ</mi> <msub> <mi>d</mi> <mn>2</mn> </msub> </mrow> <mrow> <mo>&PartialD;</mo> <mi>y</mi> </mrow> </mfrac> <mo>|</mo> </mrow> <mrow> <mo>(</mo> <mover> <mi>x</mi> <mi>Λ</mi> </mover> <mo>,</mo> <mover> <mi>y</mi> <mi>Λ</mi> </mover> <mo>,</mo> <mover> <mi>z</mi> <mi>Λ</mi> </mover> <mo>)</mo> </mrow> </msub> </mtd> <mtd> <msub> <mrow> <mfrac> <mrow> <mo>&PartialD;</mo> <mi>Δ</mi> <msub> <mi>d</mi> <mn>2</mn> </msub> </mrow> <mrow> <mo>&PartialD;</mo> <mi>z</mi> </mrow> </mfrac> <mo>|</mo> </mrow> <mrow> <mo>(</mo> <mover> <mi>x</mi> <mi>Λ</mi> </mover> <mo>,</mo> <mover> <mi>y</mi> <mi>Λ</mi> </mover> <mo>,</mo> <mover> <mi>z</mi> <mi>Λ</mi> </mover> <mo>)</mo> </mrow> </msub> </mtd> </mtr> <mtr> <mtd> <mo>.</mo> <mo>.</mo> <mo>.</mo> </mtd> <mtd> </mtd> <mtd> <mo>.</mo> <mo>.</mo> <mo>.</mo> </mtd> </mtr> <mtr> <mtd> <msub> <mrow> <mfrac> <mrow> <mo>&PartialD;</mo> <mi>Δ</mi> <msub> <mi>d</mi> <mi>m</mi> </msub> </mrow> <mrow> <mo>&PartialD;</mo> <mi>x</mi> </mrow> </mfrac> <mo>|</mo> </mrow> <mrow> <mo>(</mo> <mover> <mi>x</mi> <mi>Λ</mi> </mover> <mo>,</mo> <mover> <mi>y</mi> <mi>Λ</mi> </mover> <mo>,</mo> <mover> <mi>z</mi> <mi>Λ</mi> </mover> <mo>)</mo> </mrow> </msub> </mtd> <mtd> <msub> <mrow> <mfrac> <mrow> <mo>&PartialD;</mo> <mi>Δ</mi> <msub> <mi>d</mi> <mi>m</mi> </msub> </mrow> <mrow> <mo>&PartialD;</mo> <mi>y</mi> </mrow> </mfrac> <mo>|</mo> </mrow> <mrow> <mo>(</mo> <mover> <mi>x</mi> <mi>Λ</mi> </mover> <mo>,</mo> <mover> <mi>y</mi> <mi>Λ</mi> </mover> <mo>,</mo> <mover> <mi>z</mi> <mi>Λ</mi> </mover> <mo>)</mo> </mrow> </msub> </mtd> <mtd> <msub> <mrow> <mfrac> <mrow> <mo>&PartialD;</mo> <mi>Δ</mi> <msub> <mi>d</mi> <mi>m</mi> </msub> </mrow> <mrow> <mo>&PartialD;</mo> <mi>z</mi> </mrow> </mfrac> <mo>|</mo> </mrow> <mrow> <mo>(</mo> <mover> <mi>x</mi> <mi>Λ</mi> </mover> <mo>,</mo> <mover> <mi>y</mi> <mi>Λ</mi> </mover> <mo>,</mo> <mover> <mi>z</mi> <mi>Λ</mi> </mover> <mo>)</mo> </mrow> </msub> </mtd> </mtr> </mtable> </mfenced> <mo>=</mo> <mfenced open='(' close=')'> <mtable> <mtr> <mtd> <mfrac> <mrow> <msub> <mi>x</mi> <mn>1</mn> </msub> <mo>-</mo> <mover> <mi>x</mi> <mi>Λ</mi> </mover> </mrow> <msub> <mover> <mi>d</mi> <mi>Λ</mi> </mover> <mn>1</mn> </msub> </mfrac> <mo>-</mo> <mfrac> <mrow> <msub> <mi>x</mi> <mn>2</mn> </msub> <mo>-</mo> <mover> <mi>x</mi> <mi>Λ</mi> </mover> </mrow> <msub> <mover> <mi>d</mi> <mi>Λ</mi> </mover> <mn>2</mn> </msub> </mfrac> </mtd> <mtd> <mfrac> <mrow> <msub> <mi>y</mi> <mn>1</mn> </msub> <mo>-</mo> <mover> <mi>y</mi> <mi>Λ</mi> </mover> </mrow> <msub> <mover> <mi>d</mi> <mi>Λ</mi> </mover> <mn>1</mn> </msub> </mfrac> <mo>-</mo> <mfrac> <mrow> <msub> <mi>y</mi> <mn>2</mn> </msub> <mo>-</mo> <mover> <mi>y</mi> <mi>Λ</mi> </mover> </mrow> <msub> <mover> <mi>d</mi> <mi>Λ</mi> </mover> <mn>2</mn> </msub> </mfrac> </mtd> <mtd> <mfrac> <mrow> <msub> <mi>z</mi> <mn>1</mn> </msub> <mo>-</mo> <mover> <mi>z</mi> <mi>Λ</mi> </mover> </mrow> <msub> <mover> <mi>d</mi> <mi>Λ</mi> </mover> <mn>1</mn> </msub> </mfrac> <mo>-</mo> <mfrac> <mrow> <msub> <mi>z</mi> <mn>2</mn> </msub> <mo>-</mo> <mover> <mi>z</mi> <mi>Λ</mi> </mover> </mrow> <msub> <mover> <mi>d</mi> <mi>Λ</mi> </mover> <mn>2</mn> </msub> </mfrac> </mtd> </mtr> <mtr> <mtd> <mfrac> <mrow> <msub> <mi>x</mi> <mn>1</mn> </msub> <mo>-</mo> <mover> <mi>x</mi> <mi>Λ</mi> </mover> </mrow> <msub> <mover> <mi>d</mi> <mi>Λ</mi> </mover> <mn>1</mn> </msub> </mfrac> <mo>-</mo> <mfrac> <mrow> <msub> <mi>x</mi> <mn>3</mn> </msub> <mo>-</mo> <mover> <mi>x</mi> <mi>Λ</mi> </mover> </mrow> <msub> <mover> <mi>d</mi> <mi>Λ</mi> </mover> <mn>3</mn> </msub> </mfrac> </mtd> <mtd> <mfrac> <mrow> <msub> <mi>y</mi> <mn>1</mn> </msub> <mo>-</mo> <mover> <mi>y</mi> <mi>Λ</mi> </mover> </mrow> <msub> <mover> <mi>d</mi> <mi>Λ</mi> </mover> <mn>1</mn> </msub> </mfrac> <mo>-</mo> <mfrac> <mrow> <msub> <mi>y</mi> <mn>3</mn> </msub> <mo>-</mo> <mover> <mi>y</mi> <mi>Λ</mi> </mover> </mrow> <msub> <mover> <mi>d</mi> <mi>Λ</mi> </mover> <mn>3</mn> </msub> </mfrac> </mtd> <mtd> <mfrac> <mrow> <msub> <mi>z</mi> <mn>1</mn> </msub> <mo>-</mo> <mover> <mi>z</mi> <mi>Λ</mi> </mover> </mrow> <msub> <mover> <mi>d</mi> <mi>Λ</mi> </mover> <mn>1</mn> </msub> </mfrac> <mo>-</mo> <mfrac> <mrow> <msub> <mi>z</mi> <mn>3</mn> </msub> <mo>-</mo> <mover> <mi>z</mi> <mi>Λ</mi> </mover> </mrow> <msub> <mover> <mi>d</mi> <mi>Λ</mi> </mover> <mn>3</mn> </msub> </mfrac> </mtd> </mtr> <mtr> <mtd> <mo>.</mo> <mo>.</mo> <mo>.</mo> </mtd> <mtd> <mo>.</mo> <mo>.</mo> <mo>.</mo> </mtd> <mtd> </mtd> </mtr> <mtr> <mtd> <mfrac> <mrow> <msub> <mi>x</mi> <mn>1</mn> </msub> <mo>-</mo> <mover> <mi>x</mi> <mi>Λ</mi> </mover> </mrow> <msub> <mover> <mi>d</mi> <mi>Λ</mi> </mover> <mn>1</mn> </msub> </mfrac> <mo>-</mo> <mfrac> <mrow> <msub> <mi>x</mi> <mi>m</mi> </msub> <mo>-</mo> <mover> <mi>x</mi> <mi>Λ</mi> </mover> </mrow> <msub> <mover> <mi>d</mi> <mi>Λ</mi> </mover> <mi>m</mi> </msub> </mfrac> </mtd> <mtd> <mfrac> <mrow> <msub> <mi>y</mi> <mn>1</mn> </msub> <mo>-</mo> <mover> <mi>y</mi> <mi>Λ</mi> </mover> </mrow> <msub> <mover> <mi>d</mi> <mi>Λ</mi> </mover> <mn>1</mn> </msub> </mfrac> <mo>-</mo> <mfrac> <mrow> <msub> <mi>y</mi> <mi>m</mi> </msub> <mo>-</mo> <mover> <mi>y</mi> <mi>Λ</mi> </mover> </mrow> <msub> <mover> <mi>d</mi> <mi>Λ</mi> </mover> <mi>m</mi> </msub> </mfrac> </mtd> <mtd> <mfrac> <mrow> <msub> <mi>z</mi> <mn>1</mn> </msub> <mo>-</mo> <mover> <mi>z</mi> <mi>Λ</mi> </mover> </mrow> <msub> <mover> <mi>d</mi> <mi>Λ</mi> </mover> <mn>1</mn> </msub> </mfrac> <mo>-</mo> <mfrac> <mrow> <msub> <mi>z</mi> <mi>m</mi> </msub> <mo>-</mo> <mover> <mi>z</mi> <mi>Λ</mi> </mover> </mrow> <msub> <mover> <mi>d</mi> <mi>Λ</mi> </mover> <mi>m</mi> </msub> </mfrac> </mtd> </mtr> </mtable> </mfenced> <mo>,</mo> </mrow> </math>

for the estimated target initial iteration positionDistance from each reference node. And solving the formula (24) by using a weighted least square method, wherein the coordinate deviation of the terminal to be positioned can be solved:

wherein Q is a covariance matrix of time delay estimated values between base stations.

Order toAs the initial value of the next iteration, the iteration process is repeated until Δ x, Δ y are small enough to satisfy the set threshold μ, wherein the estimated value (x ", y", z ") output after | + | Δ y | + | Δ z | ≦ μ is the position coordinate of the terminal to be positioned.

Fig. 5 is a schematic structural diagram of a positioning system based on ultra-wideband technology according to an embodiment of the present invention. As shown in fig. 5, the positioning system 500 includes a background server 510, a plurality of base stations 520 (base station 520-1 to base station 520-k) coupled to the background server 510, and a terminal to be positioned 530 and a reference tag 540 coupled to the plurality of base stations 520.

In an embodiment of the invention, the backend server 510 includes an acquisition module 512 and a calculation module 514 coupled to the acquisition module 512. Specifically, the obtaining module 512 is configured to obtain, according to a positioning request sent by the terminal to be positioned 530, signal transmission data among the terminal to be positioned 530, the reference tag 540, and the multiple base stations 520; the calculating module 514 is configured to calculate an estimated coordinate of the terminal 530 to be positioned according to the acquired signal transmission data, perform iterative convergence for multiple times by using the estimated coordinate as an initial iterative position, and calculate a position coordinate of the terminal 530 to be positioned.

In an embodiment of the present invention, the plurality of base stations 520 includes a master base station 520-1 and slave base stations 520-2 to 520-k, configured to receive a first positioning signal transmitted by a terminal 530 to be positioned and a reference positioning signal transmitted by a reference tag 540, where the slave base stations 520-2 to 520-k are further configured to receive a first reference signal and a second reference signal transmitted from the master base station 520-1. Wherein, 3 base stations are needed for two-dimensional positioning, and 4 base stations are needed for three-dimensional positioning.

In an embodiment of the present invention, the terminal to be located 530 includes a positioning tag 532, and the positioning tag 532 is used for sending out a positioning request, wherein, for enhancing the signal, an antenna of the positioning tag 532 is disposed outside the terminal to be located 530, and the position of the antenna changes with the movement of the terminal to be located 530.

In one embodiment of the present invention, the reference tag 540 is used for transmitting a reference positioning signal to a plurality of base stations 520, and the position of the reference positioning signal is fixed and not movable.

In an embodiment of the present invention, the positioning tag 532, the reference tag 540, and the plurality of base stations 520 are connected by wireless or wired connection, and the plurality of base stations 520 and the background server 510 may also be connected by wireless or wired connection.

Fig. 6 is a schematic structural diagram of the obtaining module 512 according to an embodiment of the present invention. As shown in fig. 6, the obtaining module 512 includes a first obtaining unit 610, a second obtaining unit 620 coupled to the first obtaining unit 610, and a third obtaining unit 630 coupled to the second obtaining unit 620.

Specifically, in an embodiment of the present invention, the first obtaining unit 610 is configured to obtain positioning request data, where the positioning request data includes an arrival time of a first positioning signal transmitted by the terminal 530 to be positioned and an arrival time of a first reference signal used for unifying time of a plurality of base stations 520 receiving the first positioning signal; the second obtaining unit 620 is configured to obtain positioning assistance data, where the positioning assistance data includes an arrival time of a reference positioning signal transmitted by the reference tag 540 and an arrival time of a second reference signal for performing time unification on the plurality of base stations 520 receiving the reference positioning signal; the third obtaining unit 630 is configured to obtain location information, where the location information includes coordinate information of the reference tag 540 and the plurality of base stations 520.

Fig. 7 is a schematic structural diagram of the calculation module 514 according to an embodiment of the present invention. As shown in fig. 7, the calculation module 514 includes a first calculation unit 710, a second calculation unit 720 coupled to the first calculation unit 710, and an estimation unit 730 coupled to the second calculation unit 720.

Specifically, in an embodiment of the present invention, the first calculating unit 710 is configured to calculate a time difference of arrival between the first positioning signal and the reference positioning signal; the second calculating unit 720 is configured to calculate distance differences between the terminal to be positioned and the plurality of base stations according to the calculated arrival time differences; the pre-estimation unit 730 is configured to calculate pre-estimated coordinates of the terminal to be positioned according to the calculated distance difference by using a Fang algorithm.

It should be understood by those skilled in the art that the systems in fig. 5, 6 and 7 can be applied to the methods shown in fig. 3 and 4, and those skilled in the art can easily understand the operations of the systems in fig. 5, 6 and 7 after reading the above description, and therefore, for the sake of brevity, detailed descriptions of the specific implementation processes are omitted here.

Advantageously, the positioning method and the positioning system of the invention send a reference signal through the main base station, so that the system does not need to start the positioning clock accurately and synchronously, and can obtain the positioning information from the terminal to be positioned only by measuring the time interval between the reference signal and the positioning signal from the terminal to be positioned, thereby effectively improving the positioning precision, and in the actual demonstration, the positioning precision can reach 0.1m by using the positioning method for positioning. In addition, the node arrangement of the positioning method of the present invention includes 1 reference tag in addition to 4 base stations and 1 positioning tag, and such an arrangement can cancel the time delay of transmitting the UWB signal by the antenna of the mobile tag in the calculation. The 1 master base station transmits a reference signal to the 3 slave base stations, and the TDOA (time difference of arrival) is used for effectively avoiding the problem of base station time synchronization in the prior art.

The above description is only for the purpose of illustrating the preferred embodiments of the present invention and is not to be construed as limiting the invention, and any modifications, equivalents and improvements made within the spirit and principle of the present invention are intended to be included within the scope of the present invention.

Claims

1. A method of positioning, comprising:

a terminal to be positioned sends a positioning request;

acquiring signal transmission data among the terminal to be positioned, the reference tag and the base stations according to the positioning request; and

and calculating the estimated coordinate of the terminal to be positioned according to the acquired signal transmission data, and performing iterative convergence on the estimated coordinate for multiple times to obtain the position coordinate of the terminal to be positioned.

2. The positioning method according to claim 1, wherein the step of obtaining the signal transmission data between the terminal to be positioned, the reference tag and the plurality of base stations according to the positioning request comprises:

acquiring positioning request data, wherein the positioning request data comprises the arrival time of a first positioning signal transmitted by the terminal to be positioned and the arrival time of a first reference signal used for carrying out time unification on the plurality of base stations receiving the first positioning signal;

acquiring positioning assistance data, wherein the positioning assistance data comprises the arrival time of a reference positioning signal transmitted by the reference tag and the arrival time of a second reference signal used for unifying the time of the plurality of base stations receiving the reference positioning signal; and

and acquiring position information, wherein the position information comprises the reference label and the coordinate information of the plurality of base stations.

3. The positioning method according to claim 2, wherein the step of calculating the estimated coordinates of the terminal to be positioned according to the acquired signal transmission data comprises:

calculating a time difference of arrival of the first positioning signal and the reference positioning signal;

calculating the distance difference between the terminal to be positioned and the plurality of base stations according to the calculated arrival time difference; and

and calculating the estimated coordinates of the terminal to be positioned by using a Fang algorithm according to the calculated distance difference.

4. The positioning method of claim 3, wherein the step of calculating the time difference of arrival of the first positioning signal and the reference positioning signal comprises:

calculating the time difference of the first positioning signal and the reference positioning signal reaching the kth base station; and

and respectively calculating the time difference between the arrival of the first positioning signal and the arrival of the reference positioning signal at two base stations in the plurality of base stations.

5. The method of claim 4, wherein the step of calculating the time difference between the arrival of the first positioning signal and the arrival of the reference positioning signal at two of the plurality of base stations respectively comprises:

calculating a first positioning time reference of the plurality of base stations according to the arrival time of the first reference signal, and calculating the time difference of the first positioning signal arriving at two base stations in the plurality of base stations according to the first positioning time reference; and

and calculating second positioning time references of the plurality of base stations according to the arrival time of the second reference signal, and calculating the time difference of the reference positioning signal arriving at two base stations in the plurality of base stations according to the second positioning time references.

6. The positioning method of claim 1, further comprising:

and acquiring the position coordinates of the terminal to be positioned and the position coordinates of a target point, and controlling the terminal to be positioned to reach the target point.

7. The positioning method according to any of claims 1-6, wherein the number of the plurality of base stations is 3 when performing two-dimensional positioning; and when the three-dimensional positioning is carried out, the number of the plurality of base stations is 4.

8. A positioning system, comprising: a terminal to be positioned, a reference label, a plurality of base stations and a background server, wherein,

the terminal to be positioned comprises a positioning label and sends a positioning request through the positioning label;

the background server comprises an acquisition module and a calculation module;

the acquisition module is used for acquiring signal transmission data among the terminal to be positioned, the reference tag and the base stations according to the positioning request;

the calculation module is used for calculating the estimated coordinates of the terminal to be positioned according to the acquired signal transmission data, performing multiple iterative convergence by taking the estimated coordinates as an initial iterative position, and calculating the position coordinates of the terminal to be positioned.

9. The positioning system of claim 8, wherein the acquisition module comprises:

a first obtaining unit, configured to obtain positioning request data, where the positioning request data includes arrival time of a first positioning signal transmitted by the terminal to be positioned and arrival time of a first reference signal used for performing time unification on the plurality of base stations that receive the first positioning signal;

a second obtaining unit, configured to obtain positioning assistance data, where the positioning assistance data includes an arrival time of a reference positioning signal transmitted by the reference tag and an arrival time of a second reference signal used for time unification of the plurality of base stations that receive the reference positioning signal;

a third obtaining unit, configured to obtain location information, where the location information includes the reference tag and coordinate information of the multiple base stations.

10. The positioning system of claim 9, wherein the calculation module comprises:

a first calculation unit for calculating a time difference of arrival of the first positioning signal and the reference positioning signal;

a second calculating unit, configured to calculate distance differences between the terminal to be positioned and the base stations according to the calculated time difference of arrival; and

and the pre-estimation unit is used for calculating the pre-estimated coordinates of the terminal to be positioned by using a Fang algorithm according to the calculated distance difference.