CN106483495A - A kind of indoor sport tag location and speed-measuring method - Google Patents

Abstract

A method for locating and measuring speed of an indoor sports tag, specifically comprising the following steps: Step 1: The tag to be tested synchronously generates a linear frequency modulation continuous wave signal with a base station, and performs FFT processing on the digital intermediate frequency signals obtained by each base station according to positive and negative frequency sweeps; Step 2: Make a CFAR judgment on the FFT processing result, and obtain the positive intermediate frequency f ₊ and the negative intermediate frequency f _‑ corresponding to the positive and negative sweeps ; Step 3: Calculate the pseudo-range R of the tag to be tested relative to each base station, and the tag to be tested Relative to the velocity component v _i of each base station; Step 4: Calculate the position of the tag; Step 5: Calculate the angle of the tag relative to each base station; Step 6: Calculate the velocity and direction of the tag. The advantage of the present invention is that only using the positioning channel to realize the position and speed calculation of the indoor motion tag, has the characteristics of high precision and real-time performance, and can be directly applied to the navigation of the motion tag.

Description

A method for indoor sports tag positioning and speed measurement

technical field

The invention belongs to the field of electronic communication and relates to a positioning and speed measuring method for an indoor sports tag. The main classification number is G01S5/06.

Background technique

With the development of intelligent technology, more and more mobile robots are currently used in restaurant services, streaming distribution and other fields. Robot navigation technology is an important research direction in the field of intelligent robots, and position and velocity information are the basic elements of navigation.

Because speed is a vector information, the current mainstream speed measurement method for indoor moving tags is mainly to add an additional speed or acceleration sensor to the tag to calculate the target speed, and add an additional electronic compass or direction sensor to determine the direction, such as patent application number 201610321161 .X "Indoor Navigation Method and Device" uses gyroscopes and direction sensors to perform real-time Kalman filtering to obtain fusion navigation information; The built-in electronic compass calculates the current heading angle of the robot; Patent Application No. 201510121270.2 "A Belt-Type Wearable Indoor Mobile Positioning Terminal" uses the accelerometer and angular velocity of the inertial navigation module to sense the acceleration and angular velocity respectively to integrate the velocity and angle information. This method of speed measurement increases the cost of the label, increases the size and complexity of the label. Another positioning method for indoor motion tags is to use the track information obtained by the positioning system to perform track prediction processing. For example, patent application number 201310469003.5 "A Positioning Method for Indoor Mobile Robots" uses ultrasonic positioning to obtain absolute distance information and Dead reckoning obtains the relative distance information to realize the positioning of the moving robot; this method has a large distance information error due to the low positioning accuracy, and the error of the obtained track information is also relatively large. In addition, this is not a real-time speed measurement method. The obtained speed The information is also inaccurate.

At present, indoor tag positioning generally adopts a special high-precision indoor positioning system, among which chirp continuous wave is a commonly used signal form. At present, the main related technical documents are: Document 1, "Design and Application of Wireless Positioning System Based on Chirp Signal Realization" (Zhengzhou University, Wu Xiaoyong, master's thesis); Document 2, patent "A Precise Positioning and Equipment Based on LFM Continuous Wave Technology" (Patent Application No. 201310538331.6); Document 3, Patent "Indoor Positioning Device and Method" (Patent application number: 201410416423.1). The first two documents use the linear frequency modulation continuous wave signal system, but they are both distance measurement systems. The tag needs to measure the distance with each base station in time-sharing. In addition, the base station and the tag when measuring the distance (Document 2, equipment A and equipment B) Time-sharing and two-way distance measurement is also required, and these non-real-time properties have brought positioning and speed measurement errors to motion tags. Document 3 is a distance difference system, and its positioning accuracy and real-time performance are better than the previous two. However, for moving tags, a single forward or downward sweep cannot solve the speed-distance coupling phenomenon and cause positioning errors.

Contents of the invention

Aiming at the problem that the existing indoor positioning system has insufficient positioning and speed measurement accuracy of moving targets and requires additional speed or acceleration and direction sensors, the present invention proposes a positioning and speed measurement method for indoor motion tags.

The invention discloses a method for positioning and measuring speed of an indoor sports tag, a method for positioning and measuring a speed of an indoor sports tag, which specifically includes the following steps:

Step 1: The label to be tested and the base station synchronously generate a linear frequency modulation continuous wave signal; the modulation mode of the linear frequency modulation continuous wave signal is a triangle wave, and the digital intermediate frequency signals obtained by each base station are respectively subjected to FFT processing according to positive and negative frequency sweeps;

Step 2: Make a CFAR judgment on the FFT processing result, and obtain the positive intermediate frequency f ₊ and the negative intermediate frequency f ₋ corresponding to the positive and negative sweeps ;

Step 3: Use the positive intermediate frequency f ₊ and negative intermediate frequency f _- obtained in step 2 to calculate the pseudo-range R of the tag to be tested relative to each base station, and the velocity component v _i of the tag to be tested relative to each base station; subscripts indicate different base stations ;

Step 4: Make the difference between the pseudo-ranges obtained in step 3 to obtain the real distance difference between the base stations, and calculate the position of the tag;

Step 5: Calculate the angle of the tag relative to each base station from the position of the tag obtained in step 4;

Step 6: Use the velocity component calculated in step 3 and the angle solution calculated in step 5 to calculate the velocity and direction of the tag.

Specifically, in the step 2, the velocity components of the tags relative to each base station are calculated:

v _i = c(f ₊ + f _- - 2f _IF )/2f ₀

Where f ₀ is the starting frequency of the carrier of the base station , and f _IF is the starting frequency difference between the base station and the frequency-modulated continuous wave signal of the tag.

Specifically, the pseudorange in the step 3

R = c (f ₊ -f _- )/2µ

Where c is the speed of light, µ is the frequency modulation slope of the continuous wave.

Specifically, the angle calculation method of the tag relative to each base station in step 5 is as follows:

Establish an XY two-dimensional coordinate system, refer to the positive direction of the x -axis, where the coordinates of the base station are ( x ₀ , y ₀ ), and the coordinates of the label obtained in step 4 are ( x , y ), and the label is relative to the base station and x The included angle in the positive direction of the axis is α ₀ :

α ₀ =arctan((yy ₀ )/(xx ₀ )) .

Specifically, the specific method for calculating the movement speed and direction of the label in the step 6 is as follows:

Select the two velocity components v _a and v _b obtained in step 3, calculate the angle α between v _a and v _b , and select the velocity component with a higher velocity, here set , the angle between the label and v _b is denoted as θ , and the deflection velocity v _a is the positive direction;

The movement angle θ of the label is:

Label speed:

v=v _b /cos(θ)

Further, the calculation method of the included angle α is:

If v _a >0 , the angle between v _a and the positive direction of the x -axis α _a =α ₁ , v _a <=0 , the angle between v _a and the positive direction of the x -axis α _a =α ₁ -π ;

If v _b >0 , the angle between v _b and the positive direction of the x -axis α _b =α ₂ , v _b <=0 , the angle between v _b and the positive direction of the x -axis α _b =α ₂ -π ;

Then α=α _b -α _a ;

α ₁ and α ₂ are the angles between the base station corresponding to v _a and v _b and the positive direction of the x -axis, respectively.

Specifically, after the real distance difference between the base stations is obtained in the step 4, the position information of the tag is calculated by using the hyperbolic positioning principle.

Preferably, the digital intermediate frequency signal obtained by the base station in step 1 is obtained by the base station after mixing, filtering and amplifying the chirp continuous wave.

The advantage of the present invention is that only using the positioning channel to realize the position and speed calculation of the indoor motion tag, has the characteristics of high precision and real-time performance, and can be directly applied to the navigation of the motion tag.

Description of drawings

Fig. 1 is a schematic diagram of a specific embodiment of a hardware system capable of realizing the method of the present invention;

Fig. 2 is a schematic structural diagram of a specific embodiment of the tag, the base station, and the controller in Fig. 1;

Fig. 3 is a schematic diagram of a specific embodiment of a complete workflow of the present invention;

Fig. 4 is a schematic diagram of the velocity calculation method of the present invention;

Fig. 5 is a schematic diagram of the positioning area and the distribution of positioning devices in Embodiment 1;

FIG. 6 is a schematic diagram of the label position calculation results in Embodiment 1. FIG.

detailed description

The specific embodiment of the present invention will be further described in detail below in conjunction with the accompanying drawings.

The present invention is realized by using the existing ranging hardware system, especially the indoor positioning device disclosed in the Chinese patent "Indoor Positioning Device and Method" (patent application number: 201410416423.1).

As shown in Figures 1 to 3, a specific implementation of the indoor positioning device applicable to the positioning and speed measuring method of the indoor sports tag of the present invention is given.

FIG. 1 is a schematic structural diagram of an indoor positioning device applicable to the present invention. The positioning system device is composed of a controller, at least three non-collinear base stations and several positioning tags. The controller and the label are equipped with a communication module, the controller has a digital signal processing function, and the controller and each base station control the synchronization signal through wired or wireless means.

Fig. 2 is a specific structural diagram of the controller, base station and tags in Fig. 1 . Described controller comprises synchronous control module, ZigBee module and signal processing module, and the synchronous control module of controller connects the MCU of each base station by wire; Described base station consists of antenna, amplifier, mixer, chirp generator, filter amplifier , ADC, the data collected by the ADC of the base station is transmitted to the digital signal processor through a cable, and the chirp signal transmitted by the base station received by the tag flows to an antenna, an amplifier, a mixer, a filter amplifier, and an ADC; the tag is composed of an antenna, The chirp generator is composed of a tag MCU and a ZigBee module. After the tag MCU is synchronized with the controller through the ZigBee module, it controls the chirp generator to generate a chirp signal and sends it out through the antenna.

In the specific embodiment of Fig. 2, the synchronization of the communication signal is controlled by the MCU; the ZigBee module in the above controller is the controller communication module, the ZigBee module in the tag is the tag communication module, and ZigBee is a low power consumption based on the IEEE802.15.4 standard The local area network protocol is a wireless communication technology with short distance and low power consumption, which is well known to those skilled in the art.

A schematic flow diagram of a complete embodiment of the present invention is provided as shown in Figure 3, and the specific flow is as follows:

The tag to be tested synchronously generates a linear frequency modulation continuous wave signal with the base station. The modulation mode of the linear frequency modulation continuous wave signal is triangular wave, the bandwidth is B, the frequency modulation period is T, and the synchronization error is τ ₀ .

The local oscillator signals of each base station are as follows:

(6)

Among them, t represents time as a variable, T _up represents the time of the forward sweep stage, T _down represents the time of the negative sweep stage; A ₀ represents the amplitude of the local oscillator signal; where f _S is the carrier starting frequency of the base station; f _H = f _S +B ; the frequency modulation slope of the transmitted signal is µ = 2B/T .

The signal emitted by the tag to be tested is as follows:

(7)

Among them, T _up represents the forward sweep stage, T _down represents the negative sweep stage, the tag carrier start frequency is f ₀ , the tag carrier stop frequency is f ₁ = f ₀ +B , A ₀ represents the transmit signal amplitude, and the transmit The frequency modulation slope of the signal is µ=2B/T .

The intermediate frequency signal obtained by each base station after mixing, filtering and amplifying is:

(8)

with Represents the fixed phase part of the intermediate frequency signal, denoted as:

(9)

Take three base stations A, B, and C in the system as an example, if it is base station A, f _IF = f _A - f ₀ , Δ τ=τ _a - τ ₀ , f _d =f _da , τ _x =τ _a ; Among them, τ _a =R _a /c represents the propagation delay of the tag signal to be tested to reach base station A, f _da is the Doppler frequency generated by the tag to be tested relative to base station A, γ=γ _a means that the tag to be tested receives A The attenuation factor of the base station signal. If it is base station B f _IF = f _B - f ₀ , Δ τ = τ _b - τ ₀ , f _d = f _db , τ _x = τ _b ; where τ _b = R _b /c means the signal from tag to base station B Propagation delay, f _db is the Doppler frequency generated by the tag to be tested relative to base station B, and γ=γ _b represents the attenuation coefficient of the signal received by the tag from base station B. If it is base station C f _IF = f _C - f ₀ , Δ τ = τ _c - τ ₀ , f _d = f _dc , τ _x = τ _c ; where τ _c = R _c /c means the tag signal to base station C Propagation delay, f _dc is the Doppler frequency generated by the tag to be tested relative to base station C, and γ=γ _c represents the attenuation coefficient of the signal received by the tag from base station C. The c is the speed of light, and R _a , R _b , and R _c are the distances from the tag to base stations A, B, and C, respectively.

In Step 1, perform FFT (Fast Fourier Transformation, fast Fourier Transformation) processing on the digital intermediate frequency signals obtained by each base station according to positive and negative frequency sweeps, and then proceed to Step 2.

Step 2: Make a CFAR judgment on the FFT processing result, and obtain the intermediate frequency f ₊ and f _- corresponding to the positive and negative frequency sweeps .

(10)

Among them, µ is the frequency modulation slope of the linear frequency modulation continuous wave, f _IF is the initial frequency difference between the base station and the tag frequency modulation continuous wave signal, and f _d is the Doppler frequency generated by the tag to be tested relative to the base station. CFAR stands for Constant False-Alarm Rate, constant false alarm rate detection is a common judgment method for radar target detection.

Step 3: Use step 2 to obtain f ₊ and f _- solutions to calculate the pseudo-range of the tag to be tested relative to each base station, and the velocity component of the tag to be tested relative to each base station, the calculation formula is

R = c(f ₊ - f _- )/2µ (11)

v = c(f ₊ + f _- - 2f _IF )/2f ₀ (12)

The velocity component calculated in step 3 contains positive and negative signs, where the positive sign represents the direction of the tag relative to the base velocity component toward the base station, and the negative sign represents the direction of the tag relative to the base velocity component.

in the opposite direction towards the base station.

Step 4: The pseudo-range obtained in step 3 is subtracted in pairs to obtain the real distance difference between the base stations, and the location information of the tag is calculated. The hyperbolic positioning principle can be used for calculation. Before calculating using the hyperbolic positioning principle, the coordinate system should be established for the positioning system. For the positioning of the two-dimensional plane, first select a point in the positioning area as the coordinate origin, and then select the x -axis and y -axis Establish a two-dimensional plane coordinate system, and calculate the coordinates of the label as ( x , y ).

In step 4, the real distance difference between the base stations includes positive and negative signs, and the hyperbolic intersection is screened by using the positive and negative signs of the distance difference.

Step 5: Calculate the angle of the tag relative to each base station based on the position of the tag obtained in step 4. According to the location of the tag, combined with the location of each base station, it is easy to obtain the angle of the tag to be tested relative to each base station. For example, a specific algorithm is given as follows:

Taking the positive direction of the x -axis as a reference, where the coordinates of the base station are ( x ₀ , y ₀ ), and the coordinates of the tag to be tested obtained in step 4 are ( x , y ), then the angle between the tag relative to the base station and the positive direction of the x -axis :

α ₁ =arctan((yy ₀ )/(xx ₀ )) . (13)

Step 6: Use the velocity component calculated in step 3 and the angle information obtained in step 5 to calculate the velocity and direction of the tag.

A specific implementation of calculating the magnitude and direction of the tag velocity in step 6 is given below:

Optionally obtain the velocity components v _a and v _b of the tag to be tested relative to the two base stations A and B obtained in step 3, and the subscripts represent base stations A and B respectively, and calculate the angle of the tag to be tested relative to each base station according to step 5 Get the angle α between v _a and v _b . Select the velocity component with larger velocity, assuming , the angle between the label and v _b is denoted as θ , the speed v _b is the reference, and the direction biased to v _a is the positive direction. Figure 4 shows the schematic diagrams of the spatial relationship between the two kinds of θ and the velocity components v _a and v _b respectively, where part a represents an example of θ>0 , and part b represents an example of θ<0 .

Then the angle information θ of the label is:

(14)

The label velocity magnitude is:

v=v _b /cos(θ) (15)

The calculation method of the included angle α of the present invention is: judge whether v _a and v _b are positive or negative,

If v _a >0 , the angle between v _a and the positive direction of the x -axis α _a =α ₁ , v _a <=0 , the angle between v _a and the positive direction of the x -axis α _a =α ₁ -π ;

If v _b >0 , the angle between v _b and the positive direction of the x -axis α _b =α ₂ , v _b <=0 , the angle between v _b and the positive direction of the x -axis α _b =α ₂ -π ;

Then α=α _b -α _a .

Among them, α ₁ and α ₂ are the angles of the tag to be tested relative to the base station obtained in step 5, respectively.

Finally, the controller shown in FIG. 2 can send the calculated position and speed information of the tag to be tested through the communication link.

Provide a specific embodiment of the present invention below

In this embodiment, an indoor positioning device with a structure as shown in FIG. 2 is adopted, including a tag to be tested, a base station, and a controller. The structure and function diagram of the tag, base station, and controller is shown in FIG. 5 . The communication between the tag and the controller uses the ZigBee module, and the communication channel is also a coarse synchronization channel. The synchronization control module in the controller uses the method of directly generating local oscillator signals and transmitting them to each base station through equal-length transmission lines to perform base station synchronization. The tag has a linear frequency modulation continuous wave transmission function, and can control the transmission time, starting frequency and frequency modulation slope of the linear frequency modulation continuous wave. The base station includes a base station antenna, a base station amplifier, a chirp generator, a mixer, a filter amplifier, and an ADC; the controller structure includes a synchronous control module, a ZigBee module and a signal processing module.

In this embodiment, three base stations are set up in a square room with a side length of 100 meters. The location distribution is shown as base station A, base station B, and base station C in Fig. 5, with base station A as the coordinate origin and two sides of the room Establish a Cartesian coordinate system for the x and y axes. The position coordinates of the tag to be tested are (40m, 75m), the speed is 3.8m/s, and the angle between the direction of the speed and the positive direction of the x-axis is 103 degrees.

After the tag to be tested is roughly synchronized with the controller, the controller controls the three base stations to be fully synchronized through wired methods. The base station and the controller agree that the tag and each base station will control the chirp continuous wave generator to generate chirp continuous wave at the same time. The tag linear frequency modulation continuous wave modulation cycle T =5ms, the tag carrier start frequency f ₀ =5.2GHz, and the frequency modulation bandwidth B =500MHz.

The chirp continuous wave modulation period of each base station local oscillator signal T = 5ms, the carrier start frequency f _s = 5.201GHz, that is, f _A = f _B = f _C = 5.201GHz, and the frequency modulation bandwidth B = 500MHz, where f _IF = 1MHz, the sampling rate of the intermediate frequency signal f _c =4MHz, the number of FFT points is increased to N=2 ¹⁸ through zero padding, and the signal-to-noise ratio is 10dB.

Each base station obtains a digital intermediate frequency signal through frequency mixing, filtering, amplification, and ADC sampling, each base station transmits the obtained digital intermediate frequency signal to the controller, and the digital signal processor of the controller calculates the digital intermediate frequency signal to obtain position and speed information .

The result of the distance difference calculated by step 4 is as follows:

The difference between the distance between the tag and base station B and the distance between the tag and base station A is -37.83 (meters)

The distance difference between the tag and base station C and the tag to base station B is 17.83 (meters)

The difference between the distance from the tag to base station C and the distance from the tag to base station A is -20.00 (meters)

The coordinates of the label obtained from step 4 are (39.94, 75.07), and the positioning error is 0.088 (meters). The positioning results are shown in Figure 6. In Figure 6, the horizontal and vertical coordinates are X and Y coordinates respectively, and the intersection of three different trajectories is the final label coordinate.

The velocity components of the tag relative to each base station obtained from step 3 are as follows:

The velocity component of the tag to be tested relative to base station A is: -2.87m/s

The velocity component of the tag to be tested relative to base station B is: 2.67m/s

The velocity component of the tag to be tested relative to the C base station is: 0.64m/s

From step 5, the included angles from the label to each base station and the positive direction of the x-axis are: A base station 241.91 degrees, B base station 148.02 degrees, and C base station 22.62 degrees.

Calculated from step 6, the velocity of the tag is 3.79m/s, the angle between it and the x-axis is 102.74 degrees, the velocity error is 0.01m/s, and the angle error is 0.26 degrees.

The foregoing are various preferred embodiments of the present invention. If the preferred implementations in each preferred embodiment are not obviously self-contradictory or based on a certain preferred implementation, each preferred implementation can be used in any superposition and combination. The above examples and the specific parameters in the examples are only for clearly expressing the inventor's invention verification process, and are not used to limit the scope of patent protection of the present invention. The scope of patent protection of the present invention is still subject to its claims. The equivalent structural changes made in the specification and drawings of the present invention should be included in the protection scope of the present invention in the same way.

Claims (8)

1. An indoor motion tag positioning and speed measuring method is characterized by specifically comprising the following steps:

step 1: the tag to be tested and the base station synchronously generate a linear frequency modulation continuous wave signal; the modulation mode of the linear frequency modulation continuous wave signal is triangular wave, and FFT processing is respectively carried out on the digital intermediate frequency signals obtained by each base station according to positive and negative frequency sweep;

step 2: performing CFAR judgment on the FFT processing result to obtain the middle frequency corresponding to the positive and negative frequency sweepf ₊ And negative intermediate frequencyf _- ；

And step 3: using the median frequency obtained in step 2f ₊ And negative intermediate frequencyf _- Solving the pseudo range R of the label to be measured relative to each base station and the speed component of the label to be measured relative to each base stationv _i (ii) a Subscripts denote different base stations;

and 4, step 4: subtracting every two pseudo ranges obtained in the step (3) to obtain a real distance difference between base stations, and calculating the position of the label;

and 5: calculating the angle of the label relative to each base station according to the label position obtained in the step (4);

step 6: and (5) solving the speed magnitude and direction of the label by using the speed component calculated in the step (3) and the angle obtained in the step (5).

2. The indoor moving tag positioning and velocity measuring method according to claim 1,

in the step 2, velocity components of the tag relative to each base station are solved:

v _i = c（f ₊ + f _- - 2f _IF ）/2f ₀

whereinf ₀ For the carrier start frequency of the base station，f _IF The base station and tag are frequency modulated for the starting frequency difference of the continuous wave signal.

3. The indoor moving tag positioning and velocity measuring method according to claim 1, wherein the pseudo-range in step 3

R= c（f ₊ - f _- ）/2µ

WhereincIn order to be the speed of light,µis the chirp rate of the continuous wave.

4. The indoor moving tag positioning and velocity measuring method according to claim 1, wherein the angle of the tag with respect to each base station in the step 5 is calculated as follows:

establishing an XY two-dimensional coordinate system toxThe positive direction of the axis is taken as a reference, wherein the coordinates of the base station are (x ₀ ,y ₀ ) The coordinates of the label obtained in the step 4 are (A)x,y) The tag is relative to the base station andxthe included angle in the positive direction of the axis isα ₀ ：

α ₀ =arctan((y-y ₀ )/(x-x ₀ ))。

5. The indoor moving tag positioning and speed measuring method according to claim 1, wherein the specific method for calculating the moving speed and direction of the tag in the step 6 is as follows:

optionally selecting the two velocity components obtained in step 3v _a 、v _b Calculate outv _a Andv _b angle α, the component of greater velocity is selected, hereLabels andv _b the included angle is recorded asθDeviation speed ofv _a Is the positive direction;

angle of movement of the labelθComprises the following steps:

speed of the label:

v=v _b /cos(θ) 。

6. the indoor moving tag positioning and velocity measuring method of claim 5, wherein the included angle isαThe calculation method comprises the following steps:

if it isv _a >0，v _a Andxangle in positive direction of axisα _a =α ₁ ，v _a <=0，v _a Andxangle in positive direction of axisα _a =α ₁ -π；

If it isv _b >0，v _b Andxangle in positive direction of axisα _b =α ₂ ，v _b <=0，v _b Andxangle in positive direction of axisα _b =α ₂ -π；

Thenα=α _b -α _a ；

α ₁ Andα ₂ are respectively asv _a Andv _b corresponding base station andxthe angle in the positive direction of the axis.

7. The indoor moving tag positioning and velocity measuring method according to claim 1, wherein after the real distance difference between base stations is obtained in the step 4, the position information of the tag is calculated by using a hyperbolic positioning principle.

8. The method for positioning and measuring the speed of an indoor moving tag according to claim 1, wherein the digital intermediate frequency signal obtained by the base station in step 1 is obtained by mixing, filtering and amplifying the chirp continuous wave obtained by the base station.