A method for searching and rescuing a fallen person based on GNSS and Beidou short message

Abstract

The application provides a GNSS and Beidou short message-based search and rescue positioning method for a person falling into water, which comprises the following steps: step 1, acquiring GNSS pseudo-range, carrier phase and ephemeris observation values of a current epoch; step 2, calculating pseudo-range increments, pseudo-range increment prediction values and fault detection values of all satellites, judging and marking all satellites as fault satellites or normal satellites; step 3, correcting the pseudo-range observation values of the current epoch of the satellites; step 4, grouping the normal satellites and the fault satellites according to azimuth angles; step 5, screening the satellites used for positioning; step 6, calculating the weights of the satellites used for positioning; step 7, using the weights obtained in step 6 and the pseudo-range observation values corrected in step 3 to solve the positioning result by using a weighted least square method; and step 8, sending the positioning result by using a Beidou short message, and completing the GNSS and Beidou short message-based search and rescue positioning for the person falling into water.

Description

Technical Field

[0001] This invention relates to a method for searching and locating people who have fallen into the water, and more particularly to a method for searching and locating people who have fallen into the water based on GNSS and Beidou short message service. Background Technology

[0002] In recent years, with the increasing frequency of human activities at sea, the number of maritime accidents has been rising year by year. The workload of emergency rescue departments has increased significantly. Therefore, there is an urgent need to optimize and upgrade current maritime search and rescue technologies. Quickly and accurately determining the location of people in the water is crucial for shortening rescue time and improving the success rate of search and rescue, and has become a key to overcoming the challenges of maritime emergency search and rescue.

[0003] Currently, visual location by rescue personnel aboard search and rescue aircraft / ships remains the primary method for rescuing people who have fallen into the sea. While models such as route prediction and personnel drift prediction can assist manual search and rescue, this method requires significant manpower and resources and is inefficient. With the development of Global Navigation Satellite Systems (GNSS) and the BeiDou Navigation Satellite System, life-saving equipment supporting autonomous alarm and location for people in distress, such as search and rescue beacons, has been rapidly adopted and promoted. This GNSS / BeiDou-based positioning of people in distress uses a pseudorange single-point positioning mode, which does not require the deployment of base stations and can determine the location of people in distress at sea in real time. However, severe satellite signal reflection on the sea surface causes some pseudoranges to contain unacceptable multipath errors, i.e., satellite malfunction. The participation of malfunctioning satellites in positioning calculations will result in unacceptable positioning errors or positioning failures for people in distress. Summary of the Invention

[0004] Purpose of the invention: The technical problem to be solved by the present invention is to provide a method for searching and locating people who have fallen into the water based on GNSS and Beidou short message service, which addresses the shortcomings of the existing technology.

[0005] To address the aforementioned technical problems, this invention discloses a method for searching and locating people who have fallen into the water based on GNSS and BeiDou short message service, comprising the following steps:

[0006] Step 1: Use the GNSS measurement unit to receive and process GNSS satellite signals to obtain the GNSS pseudorange, carrier phase and ephemeris observations for the current epoch, i.e., epoch k.

[0007] Step 2: Based on the data obtained by the GNSS measurement unit, calculate the pseudorange increment, pseudorange increment prediction value and fault detection value of all satellites, and determine and mark all satellites as faulty satellites or normal satellites.

[0008] Step 3: Correct the pseudorange observations of the satellite at the current epoch;

[0009] Step 4: Group the normal satellites and faulty satellites according to their azimuth angle;

[0010] Step 5: Select satellites for positioning, that is, optimize the geometric configuration of positioning satellites according to the grouping described in Step 4;

[0011] Step 6: Calculate the weights of the satellites used for positioning;

[0012] Step 7: Based on the weights obtained in Step 6 and the pseudorange observations corrected in Step 3, the weighted least squares method is used to solve the problem and obtain the positioning result.

[0013] Step 8: Use BeiDou short message service to send the positioning results and complete the search and rescue positioning of the person who fell into the water based on GNSS and BeiDou short message service.

[0014] Furthermore, the calculation of pseudorange increments for all satellites in step 2 specifically includes:

[0015] Let any satellite be numbered i, and its measured pseudorange increment, i.e., the time difference pseudorange Δρ, be... i,k as follows:

[0016] Δρ i,k =ρ i,k -ρ i,k-1

[0017] Where, the initial value of number i is 1, ρ i,k and ρ i,k-1 These are the pseudorange observations of satellite i at epoch k and epoch k-1, respectively.

[0018] Furthermore, the calculation of the pseudorange increment prediction values ​​for all satellites in step 2 specifically includes:

[0019] Based on the carrier phase observations at the current epoch k and epoch k-1, calculate the predicted pseudorange increment for satellite i. Specifically as follows:

[0020]

[0021] Where λ is the wavelength of the carrier wave; and These are the carrier phase observations of satellite i at epoch k and epoch k-1, respectively; This refers to the time-differential carrier phase.

[0022] Furthermore, the calculation of the fault detection quantity for all satellites described in step 2 specifically includes:

[0023] Fault detection quantity s of satellite i i The details are as follows:

[0024]

[0025] Furthermore, step 2, which involves determining and labeling all satellites as faulty or normal satellites, specifically includes:

[0026] The threshold T for fault detection is calculated as follows:

[0027]

[0028] in, The fault detection quantity s of satellite i i The prior standard deviation;

[0029] The judgment is based on the following conditions: If s i If T ≤ T, then satellite i is marked as a normal satellite; otherwise, satellite i is marked as a faulty satellite.

[0030] Determine whether all satellites have been traversed. If not, increment i by 1 and recalculate the pseudorange increment, pseudorange increment prediction value, and fault detection value for that satellite. Determine and mark the satellite as either a faulty or normal satellite until all satellites have been traversed and determined.

[0031] Furthermore, the correction of the pseudorange observation value of the satellite at the current epoch, as described in step 3, specifically includes:

[0032] Correcting the pseudorange observations of the current epoch using carrier phase:

[0033]

[0034] in, ρ is a vector composed of the pseudoranges of visible satellites at epoch k after carrier phase correction, where N is the number of visible satellites at epoch k, and T is the transpose operator for a vector or matrix; k-1 =[ρ 1,k-1 ρ 2,k-1 …ρ N,k-1 ] T It is a vector composed of pseudoranges of visible satellites at epoch k-1; Δρ is a vector composed of the pseudorange increment predictions at epoch k; k =[Δρ 1,k Δρ 2,k … Δρ N,k ] T Let W be the vector composed of the measured pseudorange increments at epoch k; W is the weight matrix, determined by the following formula:

[0035]

[0036] Where W is a diagonal matrix; if satellite i (i = 1, 2, ..., N) is marked as a normal satellite, then w i =0; if satellite i is marked as a faulty satellite, then w i =1.

[0037] Furthermore, the grouping of normal and faulty satellites according to azimuth angle in step 4 specifically includes:

[0038] All satellites are divided into intervals of 45° each, ranging from 0° to 360°, according to their azimuth angles, as follows:

[0039] [0°,45°),[45°,90°),…,[315°,360°)

[0040] The number of normal and faulty satellites in each azimuth interval is counted and grouped.

[0041] Furthermore, step 5, which involves selecting satellites for positioning, specifically optimizes the geometric configuration of the positioning satellites based on the grouping described in step 4, includes:

[0042] Let S be the set of satellites used for positioning in epoch k. k ; Traverse the azimuth intervals divided in step 6, and add the normal satellites in each interval to the satellite set S used for positioning. k If the number of normal satellites in an azimuth interval is 0 and the number of faulty satellites is not 0, then the faulty satellite with the smallest fault detection value in that interval is added to the satellite set S used for positioning. k After traversing all azimuth intervals, the final satellite set S used for positioning is obtained. k .

[0043] Furthermore, the method for calculating the weights of the satellites used for positioning, as described in step 6, is as follows:

[0044]

[0045] Where, p j θ is the weight of the satellites used for positioning. j S is the set of satellites used for positioning. k The elevation angle of satellite j; s j Let be the fault detection quantity for satellite j; α and β are empirical coefficients. S is the set of satellites used for positioning. k The number of satellites in China;

[0046] Based on the weight p of the satellites used for positioning j The satellite positioning weight matrix P is obtained as follows:

[0047]

[0048] Furthermore, the specific method for obtaining the positioning result as described in step 7 includes:

[0049] The satellite positioning weight matrix P and the set of satellites used for positioning are... k The satellite pseudorange and satellite coordinates calculated based on the satellite ephemeris are used as inputs, and the weighted least squares method is used to solve for the positioning result.

[0050] Beneficial effects:

[0051] 1. This invention addresses the problems of low efficiency in search and rescue operations based on visual positioning and the significant impact of lighting conditions. Based on GNSS / BeiDou, this invention enables autonomous high-precision positioning of people who have fallen into the water, and uses BeiDou short message service to send the location of the people in the water to the search and rescue department in real time, which can greatly reduce the consumption of manpower and material resources, and the positioning effect is not affected by lighting conditions.

[0052] 2. This invention addresses the problem of multipath error interference on the sea surface in the autonomous positioning method for people who have fallen into the water based on traditional pseudorange single-point positioning. This invention proposes fault satellite detection and pseudorange correction based on carrier phase. The satellites that will ultimately participate in the positioning are selected according to the grouping based on the satellite azimuth angle. Weighted positioning calculation based on satellite elevation angle and time difference carrier phase / pseudorange is performed to achieve high-precision and reliable positioning of people who have fallen into the water. Attached Figure Description

[0053] The present invention will be further described in detail below with reference to the accompanying drawings and specific embodiments, and the advantages of the present invention in the above and / or other aspects will become clearer.

[0054] Figure 1 This is a schematic diagram of the overall process of the present invention.

[0055] Figure 2 This is a schematic diagram showing the comparison of positioning errors between the present invention and the conventional method in one embodiment. Detailed Implementation

[0056] The core of this invention is a method for searching and locating people who have fallen into water based on GNSS and BeiDou short message service. The overall flowchart is as follows. Figure 1 As shown in the figure. The selected sensor is a GNSS measurement unit that supports BeiDou short message service.

[0057] The key points of this invention are fault satellite detection and pseudorange correction based on carrier phase, positioning satellite selection based on geometric configuration optimization, and weighted least squares positioning based on satellite elevation angle and fault detection parameters. The specific steps of this invention are as follows: Figure 1 As shown, the details are as follows:

[0058] 1) The GNSS measurement unit receives and processes GNSS satellite signals to obtain the GNSS pseudorange, carrier phase and ephemeris of the current epoch (epoch k).

[0059] 2) Calculate the pseudorange increment, i.e., the time difference pseudorange, for satellite i (with an initial value of 1).

[0060] Δρ i,k =ρ i,k -ρ i,k-1

[0061] In the formula, ρ i,k and ρ i,k-1 These are the pseudorange observations of satellite i at epoch k and epoch k-1, respectively.

[0062] Based on the carrier phase observations of the current epoch and the previous epoch, the predicted pseudorange increment value of satellite i can be obtained.

[0063]

[0064] In the formula, λ is the wavelength of the carrier wave; and These are the carrier phase observations of satellite i at epoch k and epoch k-1, respectively; This refers to the time-differential carrier phase.

[0065] 3) Calculate the fault detection quantity of satellite i

[0066]

[0067] Calculate the threshold for this fault detection quantity.

[0068]

[0069] in, For s i The prior standard deviation.

[0070] If s i If ≤ T, then satellite i is marked as a normal satellite; if s i If >T, then satellite i will be marked as a faulty satellite.

[0071] 4) Determine if all satellites have been traversed. If satellite traversal is not complete, increment i by 1 and re-enter step 2) to perform fault detection on the next satellite; otherwise, proceed to the next step.

[0072] 5) Correct the pseudorange observations of the current epoch using the carrier phase according to the following formula:

[0073]

[0074] in, ρ is a vector composed of the pseudoranges of visible satellites at epoch k after carrier phase correction, where N is the number of visible satellites at epoch k, and T is the transpose operator for a vector or matrix; k-1 =[ρ 1，k-1 ρ 2，k-1 …ρ N，k-1 ] T It is a vector composed of pseudoranges of visible satellites at epoch k-1; Δρ is a vector composed of the pseudorange increment predictions at epoch k; k =[Δρ 1，k Δρ 2，k … Δρ N，k ] T is a vector composed of measured pseudorange increments at epoch k; W is the weight matrix, which can be determined by the following formula.

[0075]

[0076] In the formula, W is a diagonal matrix; if satellite i (i = 1, 2, ..., N) is marked as a normal satellite, then w i =0; if satellite i is marked as a faulty satellite, then w i =1.

[0077] 6) Group normal and faulty satellites according to their azimuth angles, and count the number of normal and faulty satellites in the azimuth angle ranges of [0°, 45°), [45°, 90°), ..., [315°, 360°).

[0078] 7) Let S be the set of satellites used for positioning in epoch k. k Traverse the azimuth intervals in step 6), and place the normal satellites in the intervals into S. k If the number of normal satellites in a certain azimuth interval is 0, but the number of faulty satellites is not 0, then the faulty satellite with the smallest fault detection value in that interval is placed in S. k To optimize the geometry of positioning satellites.

[0079] 8) Determine S k The weights of each satellite in the weighted positioning

[0080]

[0081] In the formula, θ j For S k The elevation angle of satellite j; s j (The fault detection quantity for satellite j has been calculated in step 3); α and β are empirical coefficients; For S k The number of satellites in the set.

[0082] Therefore, the satellite positioning weight matrix can be obtained.

[0083]

[0084] 9) The satellite positioning weight matrices P and S... k The satellite pseudorange and satellite coordinates calculated based on satellite ephemeris are used as inputs, and the weighted least squares method (reference: Li Zhenghang. GPS Measurement and Data Processing [M]. Wuhan University Press, 2013) is used to solve the problem and obtain the final location result of the person who fell into the water.

[0085] 10) Utilize the BeiDou short message communication function to send the drowning alarm and location results of the person who has fallen into the water to the relevant search and rescue agencies.

[0086] Example:

[0087] This invention was verified using simulation data, such as... Figure 2 As shown, the horizontal positioning error of the traditional pseudorange single-point positioning method exceeded 5m in some epochs, with a maximum error exceeding 25m. The horizontal positioning error of this method remained below 5m throughout the simulation experiment. The root mean square errors of the horizontal positioning of the traditional pseudorange single-point positioning method and the present invention were 3.10m and 1.68m, respectively. Compared to the traditional pseudorange single-point positioning method, the present invention improves the positioning accuracy of people falling into the water by 45.81%.

[0088] In its specific implementation, this application provides a computer storage medium and a corresponding data processing unit. The computer storage medium is capable of storing a computer program, which, when executed by the data processing unit, can run the invention's content regarding a GNSS and BeiDou short message-based method for searching and locating drowning victims, as well as some or all of the steps in various embodiments. The storage medium can be a magnetic disk, optical disk, read-only memory (ROM), or random access memory (RAM), etc.

[0089] Those skilled in the art will clearly understand that the technical solutions in the embodiments of the present invention can be implemented using computer programs and their corresponding general-purpose hardware platforms. Based on this understanding, the technical solutions in the embodiments of the present invention, or the parts that contribute to the prior art, can be embodied in the form of computer programs, i.e., software products. These computer program software products can be stored in a storage medium and include several instructions to cause a device containing a data processing unit (which may be a personal computer, server, microcontroller, MUU, or network device, etc.) to execute the methods described in various embodiments or certain parts of the embodiments of the present invention.

[0090] This invention provides a concept and method for searching and locating people who have fallen into the water based on GNSS and BeiDou short message service. Many methods and approaches exist for implementing this technical solution; the above description is merely a preferred embodiment of the invention. It should be noted that those skilled in the art can make various improvements and modifications without departing from the principles of this invention, and these improvements and modifications should also be considered within the scope of protection of this invention. All components not explicitly stated in this embodiment can be implemented using existing technologies.

Claims

1. A method for locating a fallen person based on GNSS and Beidou short message, characterized in that, The method comprises the following steps: Step 1, receiving and processing GNSS satellite signals by using a GNSS measurement unit to obtain GNSS pseudorange, carrier phase and ephemeris observation values of the current epoch, i.e., epoch k; Step 2, calculating the pseudorange increment, pseudorange increment prediction value and fault detection value of all satellites according to the data obtained by the GNSS measurement unit, judging and marking all satellites as fault satellites or normal satellites; Step 3, correcting the pseudorange observation value of the satellite at the current epoch; Step 4, grouping the normal satellites and fault satellites according to the azimuth; Step 5, screening the satellites used for positioning, i.e., optimizing the geometric configuration of the positioning satellites according to the grouping in step 4; Step 6, calculating the weight of the satellites used for positioning; Step 7, obtaining the positioning result by using the weighted least squares method according to the weight obtained in step 6 and the corrected pseudorange observation value in step 3; Step 8, sending the positioning result by using the Beidou short message to complete the GNSS and Beidou short message-based search and rescue positioning of the fallen personnel.

2. The GNSS and Beidou short message based positioning method for the search and rescue of the fallen personnel according to claim 1, characterized in that, The calculation of the pseudorange increment of all satellites in step 2 specifically comprises: Let any satellite number be i, its measured pseudorange increment, i.e. time-difference pseudorange Δρ i,k As follows: Δρ i,k = ρ i,k - ρ i,k-1 where i = 1, 2, 3,..., n, n is the number of satellites, and p i,k and p i,k-1 are the pseudo-range observations of satellite i at epoch k and the previous epoch, i.e., epoch k-1, respectively.

3. The GNSS and Beidou short message based positioning method for the search and rescue of the fallen personnel according to claim 2, characterized in that, The calculation of the pseudorange increment prediction value of all satellites in step 2 specifically comprises: Based on the carrier phase observation value of the current epoch k and the epoch k-1, the pseudo-range increment prediction value of the satellite i is calculated The specific process is as follows: where λ is the wavelength of the carrier; and are the carrier phase observations of satellite i at epoch k and epoch k-1, respectively; is the time-differenced carrier phase.

4. The GNSS and Beidou short message based positioning method for the search and rescue of the fallen personnel according to claim 3, characterized in that, The calculation of the fault detection value of all satellites in step 2 specifically comprises: Satellite i failure detection quantity s i In particular as follows:

5. The GNSS and Beidou short message based positioning method for the search and rescue of the fallen personnel according to claim 4, characterized in that, The judgment and marking of all satellites as fault satellites or normal satellites in step 2 specifically comprises: The threshold T of the fault detection value is calculated as follows: wherein s is the fault detection quantity for satellite i i prior standard deviation of s The satellite i is marked as a normal satellite if s i ≤ T, else the satellite i is marked as a faulty satellite. It is judged whether all satellites are traversed, if not, i is increased by 1 and the pseudorange increment, pseudorange increment prediction value and fault detection value of the satellite are recalculated, the satellite is judged and marked as a fault satellite or a normal satellite, until the traversal judgment of all satellites is completed.

6. The GNSS and Beidou short message based positioning method for the search and rescue of the fallen personnel according to claim 5, characterized in that, The correction of the pseudorange observation value of the satellite at the current epoch in step 3 specifically comprises: The carrier phase is used to correct the pseudorange observation value at the current epoch: wherein, is a vector composed of the pseudoranges of the visible satellites at epoch k after the carrier phase correction, N is the number of visible satellites at epoch k, T is the transposition operator of a vector or a matrix; ρ k-1 = [ρ 1,k-1 ρ 2,k-1 …ρ N,k-1 ] T is a vector composed of the pseudoranges of the visible satellites at epoch k-1; is a vector composed of the pseudorange increment prediction values at epoch k; Δρ k = [Δρ 1,k Δρ 2,k …Δρ N,k ] T is a vector composed of the measured pseudorange increments at epoch k; W is a weight matrix, which is determined by the following formula: where W is a diagonal matrix; w i = 0 if satellite i is labeled as a normal satellite; w i = 1 if satellite i is labeled as a failed satellite.

7. The GNSS and Beidou short message based positioning method for the search and rescue of the fallen person in water according to claim 6, characterized in that, The grouping of the normal satellites and fault satellites according to the azimuth in step 4 specifically comprises: All satellites are divided into intervals every 45° in the azimuth from 0° to 360°, i.e., the following intervals: [0°,45°),[45°,90°),…,[315°,360°) The number of normal satellites and fault satellites in each interval is counted and grouped.

8. The GNSS and Beidou short message based positioning method for the search and rescue of the fallen personnel according to claim 7, characterized in that, The screening of the satellites used for positioning in step 5, i.e., the optimization of the geometric configuration of the positioning satellites according to the grouping in step 4, specifically comprises: Let epoch k be used for positioning satellite set S k ; traverse the azimuth interval divided in step 6, put the normal satellite in each interval into the satellite set S used for positioning k ; if the number of normal satellites in the azimuth interval is 0 and the number of fault satellites is not 0, put the fault satellite with the smallest fault detection quantity in the interval into the satellite set S used for positioning k , after traversing all azimuth intervals, the final satellite set S used for positioning is obtained k .

9. The GNSS and Beidou short message based positioning method for the search and rescue of the fallen person in water according to claim 8, characterized in that, The calculation of the weight of the satellites used for positioning in step 6 is as follows: where p j is the weight of a satellite used for positioning, θ j is the set of satellites used for positioning S k is the satellite elevation angle of satellite j in the set S j is the failure detection quantity of satellite j; and a and β are empirical coefficients; is the set of satellites used for positioning S k is the number of satellites in the set S According to the weights p of the satellites for positioning j The satellite positioning weight matrix P is obtained as follows:

10. The GNSS and Beidou short message based positioning method for the search and rescue of the fallen personnel according to claim 9, characterized in that, The method for obtaining the positioning result in step 7 specifically comprises: a satellite positioning weight matrix P, a satellite set S used for positioning k The positioning result is obtained by using a weighted least square method with the satellite positioning weight matrix P, the satellite pseudoranges in the satellite set S used for positioning and the satellite coordinates calculated according to the satellite ephemeris as inputs.

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