Indoor positioning method based on Beidou pseudolite

Abstract

The invention discloses an indoor positioning method based on Beidou pseudo satellites. The method comprises the following steps: broadcasting a Beidou B1 signal by using a Beidou pseudo satellite, radiating the Beidou signal to a positioning area through a transmitting antenna, outputting carrier-to-noise ratios of a plurality of fixed point locations through a receiver in an actual positioning scene, establishing a carrier-to-noise ratio attenuation model by using a least square method, and performing positioning on the carrier-to-noise ratio attenuation model. In the actual positioning process, B1 frequency point signals of different pseudo codes sent by a plurality of transmitting antennas are received, carrier-to-noise ratio information of the signals is obtained, the distance from a receiver to the transmitting antennas is estimated through a carrier-to-noise ratio attenuation model, then the position is calculated by using a weighted centroid positioning method, and finally, filtering is performed by using a Kalman filtering algorithm, so that the positioning accuracy is improved. According to the method, the reliability and the stability of pseudo satellite positioning are improved, and the problem of inaccurate positioning in the prior art is solved.

Description

TECHNICAL FIELD

[0001] The application belongs to the field of satellite positioning technology, and particularly relates to an indoor positioning method based on a Beidou pseudo-satellite. BACKGROUND

[0002] In the production operation process of a large indoor scene such as a large factory, the internal personnel need to be positioned. With the development of indoor positioning technology, more and more positioning technologies are also used in factory production. Among them, the UWB positioning technology and the Bluetooth positioning are the most widely used at present. However, the UWB has the problems of limited user capacity and high equipment cost. The Bluetooth positioning has the problem of limited positioning range, and cannot achieve full coverage in a large factory. The pseudo-satellite positioning technology simulates and broadcasts Beidou signals, and the signal coverage range is wide. The outdoor Beidou navigation positioning terminal can still receive the pseudo-satellite signals indoors. Therefore, when the staff enter the factory from outdoors, the positioning can be realized without replacing the terminal equipment or switching other positioning means in the equipment, thereby saving the additional terminal cost. In addition, the pseudo-satellite signal transmitting equipment can further reduce the cost through the multi-channel design.

[0003] The existing technology such as the conventional pseudo-range positioning method is generally used in outdoor space. When used in indoor space such as a large factory, the pseudo-range fluctuation caused by the multipath effect in the factory is large, and the positioning error is prone to be large. Therefore, it is necessary to propose an indoor positioning method based on a Beidou pseudo-satellite to solve the above problems. SUMMARY

[0004] The technical problem to be solved by the application is to provide an indoor positioning method based on a Beidou pseudo-satellite, aiming to solve the problem of poor positioning accuracy of internal personnel in a large factory. Through factory environment channel modeling, the received carrier-to-noise ratio of multiple pseudo-satellite signals is used for positioning, and the stability of personnel positioning is improved by combining the Kalman filtering algorithm. The personnel positioning accuracy requirement is ensured, and the equipment cost is reduced, thereby providing technical support for factory personnel management.

[0005] To solve the above technical problems, the technical scheme adopted by the application is as follows: An indoor positioning method based on a Beidou pseudo-satellite, comprising the following steps: S1, broadcasting a Beidou signal by a Beidou pseudo-satellite, and radiating the Beidou signal to a positioning area through multiple transmitting antennas; S2, receiving the Beidou signal by a receiver and outputting carrier-to-noise ratio information; calculating an attenuation coefficient by using a logarithmic attenuation model to determine an attenuation model of the received carrier-to-noise ratio in the positioning scene; S3, calculating a propagation distance by the attenuation model in step S2; S4, calculating a positioning result by using a weighted centroid positioning method according to the propagation distance.

[0006] Preferably, the Beidou pseudolite is a Beidou simulator, and the Beidou signal broadcast by the Beidou simulator is a Beidou B1 signal frequency band, which can also be received by a common commercial receiver.

[0007] Preferably, the transmitting antennas are fixedly arranged on the side walls on both sides of the positioning area.

[0008] Preferably, the number of the transmitting antennas is not less than N, preferably 4; and the deployment interval of the transmitting antennas is equal to the width of the positioning area.

[0009] Preferably, a rectangular coordinate system is constructed for the positioning area to determine the coordinate point of each transmitting antenna in the positioning area.

[0010] Preferably, in step S2, the Beidou signal is received by the receiver, and the carrier-to-noise ratio information is output, and the attenuation coefficient is calculated by using a logarithmic attenuation model to determine the attenuation model of the received carrier-to-noise ratio in the positioning scene, and the step S2 specifically includes the following steps: S201: a single Beidou signal is transmitted in the positioning scene at a determined transmitting power; along the signal transmitting direction, a fixed point is selected every certain distance, the distance from the fixed point to the transmitting antenna is calculated, and the Beidou simulation signal is received by the receiver and the carrier-to-noise ratio is output; S202: the obtained carrier-to-noise ratio is curve-fitted to calculate the attenuation coefficient, thereby determining the attenuation model.

[0011] Preferably, step S202 specifically includes the following steps: an indoor wireless signal attenuation model is constructed in an ideal environment: ; (1) In the formula, is a power attenuation value, in dB; is the frequency of the wireless signal, in MHz, is the transmission distance of the wireless signal, in kilometers; When the frequency of the wireless signal is known, according to formula (1), the attenuation model mathematical formula in the indoor scene is defined as follows: ; (2) In the formula, is a fixed loss value, is an attenuation coefficient; The carrier-to-noise ratio output by the receiver is the ratio of the received power of the signal to the noise power spectral density, and the formula is: ; (3) In the formula, is the carrier-to-noise ratio, is the signal received power, ​Noise power spectral density, which is determined by the noise figure of the receiver; the signal receiving power is determined by the transmitting power, antenna gain and loss, and the calculation formula is as follows: ; (4) In the formula, is the transmitting power, is the antenna gain, is the receiver gain, is other loss; The attenuation model formula of the carrier-to-noise ratio is: ; (5) In formula (5), is a constant term, defined as , so the attenuation model of the carrier-to-noise ratio is finally: ; (6) The least square method is used for curve fitting, and the fitting model is: ; (7) Through the carrier-to-noise ratio and distance information collected in step S201, the values of and are calculated, and the attenuation model of the carrier-to-noise ratio in the positioning scene is obtained.

[0012] Preferably, the step S3 uses the carrier-to-noise ratio attenuation model to calculate the propagation distance, including the following steps: S301, before positioning, obtaining the carrier-to-noise ratio value of the receiver output signal at a fixed distance from the antenna , and using the attenuation model calculated in step S2 to estimate the output carrier-to-noise ratio of the receiver at the fixed distance .

[0013] S302, subtracting from to compensate for the difference in K value caused by different transmitting powers; S303, during positioning, collecting the real-time output signal carrier-to-noise ratio of the receiver, and substituting the collected data into the attenuation model to calculate the distance of the receiver from the signal transmitting antenna.

[0014] Preferably, in the actual positioning process, if the number of transmitting antennas is more than 4 and the number of receiver output carrier-to-noise ratios is more than 4; then select the distance values corresponding to the 4 largest carrier-to-noise ratios in the output multiple carrier-to-noise ratios, and perform weighted centroid positioning.

[0015] Preferably, the weighted centroid positioning method is as follows: S401, taking the distance from the receiver to the transmitting antenna calculated in step S3 as the reciprocal of the weight corresponding to the coordinate of the transmitting antenna and normalizing, the formula is as follows: ; (8) In the formula, is the normalized weight value; S402, the positioning result is calculated by using the weighted centroid positioning method: ; (9) ; (10) In the formula, , is the coordinate of the transmitting antenna in the positioning area; S403, the positioning result is filtered by using the Kalman filtering algorithm to obtain the final positioning result.

[0016] The beneficial effects of the present application are as follows: 1. Compared with the conventional positioning method, the pseudo-satellite positioning technology adopted in the present application has no user capacity limit, the signal coverage distance is far, and the terminal can be continuously positioned in and out of the factory building without switching the terminal or signal.

[0017] 2. The present method uses the received signal carrier-to-noise ratio for positioning, compared with the conventional pseudo-satellite positioning method, such as pseudo-range positioning method, high-precision clock synchronization is required between pseudo-satellite base stations, and in indoor environment, additional equipment is required to achieve high-precision clock synchronization, and the technical difficulty is great.

[0018] 3. The present method eliminates the distance calculation error caused by different terminal noises by establishing a signal model on site and using the actual signal transmission link loss compensation method. BRIEF DESCRIPTION OF DRAWINGS

[0019] Figure 1 is the flow chart of the positioning method of the present application; Figure 2 is the transmitting antenna deployment diagram in the embodiment of the present application; Figure 3 is the carrier-to-noise ratio acquisition schematic diagram in the embodiment of the present application. DETAILED DESCRIPTION

[0020] Embodiment one: As Figure 1 shown, an indoor positioning method based on Beidou pseudo-satellite includes the following steps: S1, Beidou signals are broadcasted by using Beidou pseudo-satellite, and the Beidou signals are radiated to the positioning area through multiple transmitting antennas; S2, receiving the Beidou signal using a receiver and outputting carrier-to-noise ratio information; calculating an attenuation coefficient using a logarithmic attenuation model to determine an attenuation model of the received carrier-to-noise ratio in a positioning scenario; S3, calculating the propagation distance through the attenuation model in step S2; S4, calculating a positioning result using a weighted centroid positioning method according to the propagation distance.

[0021] Preferably, the Beidou pseudolite is a Beidou simulator, and the Beidou signal broadcast by the Beidou simulator is a Beidou B1 signal frequency band, which can also be received by a common commercial receiver.

[0022] Preferably, the transmitting antennas are fixedly arranged on the side walls on both sides of the positioning area.

[0023] Preferably, the number of transmitting antennas is not less than N, preferably 4; and the deployment interval of the transmitting antennas is equal to the width of the positioning area.

[0024] Preferably, a rectangular coordinate system is constructed for the positioning area to determine the coordinate point of each transmitting antenna in the positioning area. ).

[0025] Preferably, in step S2, the Beidou signal is received using a receiver and carrier-to-noise ratio information is outputted, and an attenuation coefficient is calculated using a logarithmic attenuation model to determine an attenuation model of the received carrier-to-noise ratio in a positioning scenario, which specifically includes the following steps: S201, deploying a single Beidou signal transmitter in a positioning scenario at a determined transmitting power; selecting a fixed point every certain distance along the signal transmitting direction, calculating the distance from the fixed point to the transmitting antenna, and receiving the Beidou simulated signal using a receiver and outputting the carrier-to-noise ratio; S202, performing curve fitting on the obtained carrier-to-noise ratio to calculate the attenuation coefficient and thus determine the attenuation model.

[0026] Preferably, step S202 specifically includes the following steps: constructing an indoor wireless signal attenuation model in an ideal environment: ; (1) In the formula, is a power attenuation value, in dB; is the frequency of the wireless signal, in MHz, is the transmission distance of the wireless signal, in kilometers; When the frequency of the wireless signal is known, according to formula (1), the attenuation model mathematical formula in an indoor scenario is defined as follows: ; (2) In the formula, is a fixed loss value, is an attenuation coefficient; The carrier-to-noise ratio output by the receiver is the ratio of the received power of the signal to the noise power spectral density, and the formula is: ; (3) In the formula, is the carrier-to-noise ratio, is the received power of the signal, is the noise power spectral density, which is determined by the noise figure of the receiver; the received power of the signal is determined by the transmission power, antenna gain and loss, and the calculation formula is as follows: ; (4) In the formula, is the transmission power, is the antenna gain, is the receiver gain, is other losses; The formula of the attenuation model of the carrier-to-noise ratio is: ; (5) In formula (5), is a constant term, defined as , so the final attenuation model of the carrier-to-noise ratio is: ; (6) The least squares method is used for curve fitting, and the fitting model is: ; (7) Through the carrier-to-noise ratio and distance information collected in step S201, the values of and are calculated to obtain the attenuation model of the carrier-to-noise ratio in the positioning scene.

[0027] Preferably, the step S3 uses the carrier-to-noise ratio attenuation model to calculate the propagation distance, including the following steps: S301, before positioning, obtaining the carrier-to-noise ratio value of the receiver output signal at a fixed distance from the antenna , and using the attenuation model calculated in step S2 to estimate the output carrier-to-noise ratio of the receiver at the fixed distance .

[0028] S302, subtracting from to compensate for the difference in K value caused by different transmission powers; S303, during positioning, collecting the real-time output signal carrier-to-noise ratio of the receiver, and substituting the collected data into the attenuation model to calculate the distance of the receiver from the signal transmitting antenna.

[0029] Preferably, in the actual positioning process, if the number of transmitting antennas is more than 4, the number of receiver output carrier-to-noise ratios is also more than 4; then the distance values corresponding to the 4 largest carrier-to-noise ratios in the output multiple carrier-to-noise ratios are selected, and weighted centroid positioning is performed.

[0030] Preferably, the weighted centroid positioning method is as follows: S401, taking the reciprocal of the distance from the receiver to the transmitting antenna calculated in step S3 as the weight corresponding to the coordinate of the transmitting antenna and performing normalization processing, the formula is as follows: ; (8) In the formula, is the normalized weight value; S402, calculating the positioning result by using the weighted centroid positioning method: ; (9) ; (10) In the formula, , is the coordinate of the transmitting antenna in the positioning area; S403, filtering the positioning result by using the Kalman filtering algorithm to obtain the final positioning result.

[0031] Embodiment two: The embodiment provides a flow method of an indoor positioning method based on a Beidou pseudolite in specific implementation, and the specific process is as follows: Step 1. A Beidou signal is broadcast by using a Beidou pseudolite, and the Beidou signal is radiated to a positioning area through multiple transmitting antennas.

[0032] The Beidou simulator broadcasts a Beidou signal, in order to ensure that a commercial receiver can simultaneously receive an outdoor navigation signal and a Beidou signal broadcast by the indoor Beidou pseudolite, the signal system is designed with reference to a B1C signal, and secondly, in order to ensure the accuracy of subsequent distance estimation, the signal transmission power should not be too large, and the specific value is determined according to the performance of the receiver. The maximum power signal of the signal transmitted by the transmitting antenna after space transmission reaches the receiver end, and should be in the amplification area of the signal receiving and processing of the receiver, so as to avoid the situation that the signal carrier-to-noise ratio output does not change due to oversaturation, thereby causing errors in the distance estimated by the carrier-to-noise ratio.

[0033] The transmitting antenna radiates a Beidou signal, the transmitting antenna is deployed on the side walls on both sides of the positioning area, at least 4 are deployed, the deployment interval is determined by the width of the positioning area, and the coordinates (x, y) are known.

[0034] Examples Figure 2 ​As shown, in a rectangular factory building, 6 pseudo-satellite transmitting antennas are deployed, the antennas are deployed on both sides of the long side of the factory building, the deployment interval is equal to the width, and the deployment height is 1.5 meters.

[0035] Step 2. Receive the Beidou signal using the receiver and output the carrier-to-noise ratio information, calculate the attenuation coefficient using the logarithmic attenuation model, and determine the attenuation model of the received carrier-to-noise ratio in the positioning scenario.

[0036] Further, step 2 includes the following sub-steps: Step 201, in the positioning scenario, a single Beidou signal is transmitted, and along the direction of the signal transmission, a fixed point is selected every certain distance, the distance from the fixed point to the transmitting antenna is calculated, and a receiver is used to receive the Beidou simulation signal and output the carrier-to-noise ratio.

[0037] Examples such as Figure 3 As shown, to ensure the accuracy of the subsequent attenuation model fitting, a fixed point is selected every 1 meter, the transmitting antenna height in step 1 is consistent, and the height of the receiver is consistent with the height used later. Secondly, after ensuring that the maximum power signal received by the receiver is in the amplification zone of the receiver, the maximum distance of the fixed point is selected, and the carrier-to-noise ratio output by the receiver needs to be greater than or equal to 40 dB.Hz.

[0038] Step 202, using the logarithmic attenuation model, the obtained carrier-to-noise ratio is curve-fitted, the attenuation coefficient is calculated, and the attenuation model is determined.

[0039] Further, the transmitting power of the Beidou simulation signal in step 201 is known.

[0040] Under ideal conditions, construct an indoor wireless signal attenuation model: ; (1) In the formula, is the power attenuation value, unit dB; is the frequency of the wireless signal, unit MHz, is the transmission distance of the wireless signal, unit kilometer; When the frequency of the wireless signal is known, according to formula (1), the attenuation model mathematical formula under the indoor scene is defined as follows: ; (2) In the formula, is the fixed loss value, is the attenuation coefficient; The carrier-to-noise ratio output by the receiver is the ratio of the received power of the signal to the noise power spectral density, and the formula is: ; (3) In the formula, is the carrier-to-noise ratio, is the signal received power, is the noise power spectral density, which is determined by the noise figure of the receiver; the signal received power is determined by the transmitting power, antenna gain and loss, and the calculation formula is as follows: ; (4) In the formula, is the transmitting power, is the antenna gain, is the receiver gain, is other loss; The attenuation model formula of the carrier-to-noise ratio is: ; (5) In formula (5), is a constant term, defined as , so the attenuation model of the carrier-to-noise ratio is finally: ; (6) The least squares method is used for curve fitting, and the fitting model is: ; (7) Through the carrier-to-noise ratio and distance information collected in step S201, the values of and are calculated, and the attenuation model of the carrier-to-noise ratio in the positioning scene is obtained.

[0041] Step 3. Calculate the propagation distance through the attenuation model in step 2.

[0042] Further, the calculation of the propagation distance includes the following sub-steps: Step 301, before positioning, obtain the signal carrier-to-noise ratio value of the receiver output at a distance of 1 meter from the antenna , and estimate the output carrier-to-noise ratio of the receiver at 1 meter using the attenuation model calculated in step three .

[0043] Step 302, subtract from to compensate for the difference in K value caused by different transmitting powers.

[0044] Step 303, during the positioning process, calculate the distance of the receiver from the signal transmitting antenna according to the attenuation model based on the real-time output signal carrier-to-noise ratio of the receiver.

[0045] 4. According to the propagation distance, the weighted centroid positioning method is used to calculate the positioning result.

[0046] As Figure 2As shown, 6 transmitting antennas are deployed in this example, so in the actual positioning process, the number of different signals received by the receiver can be more than 4, and the number of output carrier-to-noise ratios of the receiver can also be more than 4, at this time, 4 maximum carrier-to-noise ratios are selected from the multiple output carrier-to-noise ratios, and the weighted centroid positioning method is used to calculate the distance value corresponding to the 4 maximum carrier-to-noise ratios. Step 401: taking the inverse of the distance between the receiver and the transmitting antenna obtained in step three as the weight of the coordinate of the transmitting antenna and performing normalization processing, the formula is as follows: ; (8) In the formula, is the normalized weight value.

[0047] Step 402: using the weighted centroid positioning method to calculate the positioning result, the formula is as follows: ; (9) ; (10) In the formula, , is the horizontal and vertical coordinates of the transmitting antenna .

[0048] Step 403: using the Kalman filtering algorithm to filter the positioning result to obtain the final positioning result.

[0049] The above description describes one preferred embodiment of the present application, which should not be regarded as a limitation on the scope of protection of the claims of the present application. Any modification, equivalent replacement and improvement without departing from the principles and spirits of the present application should be regarded as within the scope of protection of the claims of the present application.

Claims

1. A method for indoor positioning based on Beidou pseudolite, characterized in that, The method comprises the following steps: S1, broadcasting a Beidou signal by using a Beidou pseudo-satellite, and radiating the Beidou signal to a positioning area through a plurality of transmitting antennas; S2, receiving the Beidou signal by using a receiver, and outputting carrier-to-noise ratio information; calculating an attenuation coefficient by using a logarithmic attenuation model, and determining an attenuation model of the received carrier-to-noise ratio in a positioning scenario; S3, calculating a propagation distance by using the attenuation model in step S2; S4, calculating a positioning result by using a weighted centroid positioning method according to the propagation distance. 2.The indoor positioning method based on Beidou pseudolite of claim 1, characterized in that, The Beidou pseudo-satellite is a Beidou simulator, and the Beidou signal broadcasted by the Beidou simulator is a Beidou B1 signal frequency band. 3.The indoor positioning method based on Beidou pseudolite of claim 1, characterized in that, The transmitting antennas are fixedly arranged on side walls on both sides of the positioning area.

4. The indoor positioning method based on Beidou pseudolite according to claim 3, characterized in that, The number of the transmitting antennas is not less than N, and the deployment interval of the transmitting antennas is equal to the width of the positioning area.

5. The indoor positioning method based on Beidou pseudolite according to claim 4, characterized in that, A rectangular coordinate system is constructed for the positioning area, and coordinates of each transmitting antenna in the positioning area are determined .

6. The indoor positioning method based on Beidou pseudolite according to claim 1, characterized in that, In step S2, the Beidou signal is received by using the receiver, and the carrier-to-noise ratio information is outputted, the attenuation coefficient is calculated by using the logarithmic attenuation model, and the attenuation model of the received carrier-to-noise ratio in the positioning scenario comprises the following steps: S201, deploying a single Beidou signal transmitter in the positioning scenario at a determined transmitting power; selecting a fixed point every certain distance along the signal transmitting direction, calculating the distance from the fixed point to the transmitting antenna, and receiving the Beidou simulated signal by using the receiver and outputting the carrier-to-noise ratio; S202, performing curve fitting on the obtained carrier-to-noise ratio, calculating the attenuation coefficient, and thus determining the attenuation model.

7. The indoor positioning method based on Beidou pseudolite according to claim 6, characterized in that, Step S202 specifically comprises the following steps: constructing an indoor wireless signal attenuation model in an ideal environment: ；（1） In the formula, is a power attenuation value, in dB; is a frequency of the wireless signal, in MHz, is a transmission distance of the wireless signal, in kilometers; When the frequency of the wireless signal is known, according to formula (1), the attenuation model mathematical formula of the indoor scenario is defined as follows: ；（2） wherein is a fixed loss value, is a decay coefficient; The carrier-to-noise ratio outputted by the receiver is the ratio of the received power of the signal to the noise power spectral density, and the formula is: ；（3） In the formula, The carrier-to-noise ratio is The signal received power is The noise power spectral density is determined by the noise figure of the receiver; the signal received power is determined by the transmission power, antenna gain and loss, and the calculation formula is as follows: ；（4） wherein Ptransmit is the transmit power, Gantenna is the antenna gain, Greceiver is the receiver gain, is other losses; The attenuation model formula of the carrier-to-noise ratio is: ；（5） In equation (5), is a constant term, defined as , so the attenuation model of the carrier-to-noise ratio is finally ；（6） curve fitting is performed by using the least square method, and the fitting model is: ；（7） Through the carrier-to-noise ratio and distance information collected in step S201, the value of and is calculated to obtain the carrier-to-noise ratio attenuation model in the positioning scenario. 8.The indoor positioning method based on Beidou pseudolite of claim 7, wherein, In step S3, the carrier-to-noise ratio attenuation model is used to calculate the propagation distance, which comprises the following steps: S301, before positioning, obtaining the output signal carrier-to-noise ratio value of the receiver at a fixed distance from the antenna , and estimating the output carrier-to-noise ratio of the receiver at the fixed distance by using the attenuation model calculated in step S2 ; S302, the with subtracted to compensate for the difference in K value due to different transmit power; S303, in the positioning process, collecting the signal carrier-to-noise ratio outputted by the receiver in real time, and substituting the collected data into the attenuation model to obtain the distance from the receiver to the signal transmitting antenna. 9.The indoor positioning method based on Beidou pseudolite of claim 4, characterized in that, In the actual positioning process, if the number of the transmitting antennas is more than N, the number of the carrier-to-noise ratio outputted by the receiver is also more than N; then the distance values corresponding to the N maximum carrier-to-noise ratios in the outputted plurality of carrier-to-noise ratios are selected, and weighted centroid positioning is performed.

10. The indoor positioning method based on Beidou pseudolite according to claim 9, characterized in that, The weighted centroid positioning method is as follows: S401, take the inverse of the distance between the receiver and the transmitting antenna calculated in step S3 as the weight corresponding to the coordinate of the transmitting antenna and normalized, the formula is as follows: ；（8） In the formula, is a normalized weight value; S402, calculating a positioning result by using the weighted centroid positioning method: ；（9） ；（10） In the formula, , is a transmit antenna coordinates in the positioning area; S403, filtering the positioning result by using a Kalman filtering algorithm, and obtaining a final positioning result.

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