A semi-closed combination based UWB TOA-GNSS integrated navigation system and method

Abstract

The application provides a UWB TOA-GNSS combined navigation system and method based on semi-tight combination, position is solved through pseudorange single point positioning, and then the position is tightly combined with original observation of UWB TOA, and the specific method is that position information is solved through the pseudorange single point positioning method, then a circle is drawn with the position of UWB as the center, and the distance from the true value to the UWB and the distance from the single point positioning value to the UWB are taken as the radii, then the distance from the true value to the UWB is subtracted from the UWB value and divided by the difference between the true value and the single point positioning value to solve the value close to the single point positioning value, and the true value solution; the application can be used in the field of insufficient GNSS signal or the field needing to enhance the navigation precision, can be used in the scene needing to enhance the GNSS navigation performance outdoors, and can effectively improve the precision of single satellite navigation or traditional UWB TOA-GNSS tight combination; the application not only further improves the positioning precision, but also proves that when only one UWB can work, the positioning precision can still be greatly improved.

Description

Technical Field

[0001] This invention belongs to the field of integrated navigation technology, specifically, it relates to a UWBTOA-GNSS integrated navigation system and method based on semi-compact integration. Background Technology

[0002] GNSS stands for Global Navigation Satellite System, which provides positioning and navigation services via satellites. However, satellite navigation technology still has certain limitations in practical applications. Due to the fragility of satellite signals, in environments with severe signal blockage, signals are significantly obstructed, leading to degraded signal quality and a reduced number of observation equations, thus severely impacting the positioning accuracy and reliability of satellite navigation. Furthermore, the poor geometric distribution of satellites along the elevation direction results in larger errors in the elevation direction of the positioning results. To compensate for these shortcomings, integrated navigation methods are typically used to improve positioning capabilities.

[0003] In recent years, Ultra-Wide Band (UWB) technology has received considerable attention in the field of wireless communication research. UWB technology boasts advantages such as low cost, strong signal penetration, high ranging accuracy, and strong resistance to multipath propagation. Furthermore, the power of UWB signals is significantly lower than that of GNSS signals, allowing them to coexist without interfering with GNSS signals. Therefore, UWB-GNSS integrated navigation holds great promise.

[0004] Among the combined UWB and GNSS methods, the UWB-GNSS compact combination method is widely used. Traditional UWB and GNSS compact combination integrates the original observations into a linearized equation for calculation, resulting in significant positioning errors. This method is similar to pseudorange point positioning. It first prepares data and sets an initial solution, then linearizes the nonlinear equations, and solves by simply combining the original UWB equations and the point positioning equations to obtain the final position information. The advantage of this method is its simplicity and minimal need to modify the original equations; however, its disadvantage is limited improvement in accuracy. Summary of the Invention

[0005] To address the aforementioned problems, this invention proposes a UWBTOA-GNSS integrated navigation system and method based on semi-compact combination. The position is solved by pseudorange single-point positioning, and then tightly combined with the original UWBTOA observations. Based on the traditional UWBTOA-GNSS tight combination, the positioning accuracy of the integrated navigation is effectively improved.

[0006] This invention is achieved through the following technical solution:

[0007] A UWBTOA-GNSS integrated navigation method based on semi-compact combination:

[0008] The method specifically includes the following steps:

[0009] Step 1: Obtain the target point's location information using the pseudorange single-point positioning method (SPP).

[0010] Step 2: Construct a sphere with the location of the UWB base station as the center and the distance between the UWB base station and the mobile station as the radius;

[0011] Step 3: Determine a point on the sphere described in Step 2 such that its distance from the target point in Step 1 is minimized. The determined point is the positioning result of the semi-tight combination method.

[0012] Furthermore,

[0013] For all visible satellites n, pseudorange measurements ρ are collected at the same measurement time using the pseudorange point positioning method (SPP). (n) And calculate various deviation components in the measured values, such as δt. (n) I (n) and T (n) ,

[0014] Where δt (n) Let I be the satellite clock bias of satellite n. (n) Let T be the ionospheric delay error of satellite n. (n) For satellite n, the tropospheric delay error;

[0015] According to the formula ρ c (n) =ρ (n) +δt (n) -I (n) -T (n) Calculate the pseudorange measurement value after error correction;

[0016] At the same time, the satellite's spatial position coordinates, corrected for Earth's rotation, are calculated based on the ephemeris of visible satellites.

[0017] Furthermore,

[0018] The standard deviation of the ranging error between the UWB base station and the mobile station is 5 cm.

[0019] The minimum error is the distance measurement error between the point on the sphere and the actual position of the rover station.

[0020] The maximum error is the sum of twice the actual distance between the UWB base station and the mobile station and the UWB ranging error.

[0021] Furthermore,

[0022] Draw circles with radii of the distance from the ground truth value to the UWB base station and the distance from the pseudorange point positioning value to the UWB base station, respectively. Divide the distance from the ground truth value to the UWB value and then divide the result by the difference between the ground truth value and the pseudorange point positioning value. Take the ground truth value that is closest to the pseudorange point positioning value as the positioning result.

[0023] Furthermore,

[0024] Using the information obtained above, the nonlinear equation is linearized to obtain the matrix equation:

[0025] G[ΔxΔyΔzΔδt u ] T =b

[0026] Where [ΔxΔyΔzΔδt] u ] T G is the difference vector between the unfolded point and the receiver position and the receiver clock error result, G is the observation vector matrix between the unfolded point and each satellite, and b is the difference vector between the pseudorange and the distance between the unfolded point and the satellite.

[0027] The solution to the GPS pseudorange positioning linear matrix equation is as follows:

[0028] [ΔxΔyΔzΔδt u ] T =(G T G -1 )G T b

[0029] Update the roots of the nonlinear equation system, and update the receiver position coordinate x according to the following formula. k Clock difference δt u,k :

[0030] x k =x k-1 +Δx=x k-1 +[ΔxΔyΔz] T

[0031] δt u,k =δt u,k-1 +Δδt u .

[0032] Furthermore,

[0033] Construct a sphere with the coordinates of the UWB base station as its center and the measured distance between the UWB base station and the mobile station as its radius:

[0034]

[0035] Among them (uwb) x uwb yuwb z P represents the three-dimensional location coordinates of the UWB base station. uwb The distance measurement value between the UWB base station and the UWB mobile station;

[0036] Find the equation of the line connecting the UWB base station and the single-point positioning result:

[0037]

[0038] Among them (spp) x ,spp y ,spp z () represents the coordinates of the single-point positioning result of the mobile station;

[0039] Solving the above two equations simultaneously yields two sets of positional solutions after semi-compact combination. Comparing the two sets of positional solutions, the distance (spp) is selected. x ,spp y ,spp z The closer location solution is used as the positioning result.

[0040] A UWBTOA-GNSS integrated navigation system based on semi-compact combination:

[0041] The navigation system includes a main navigation system and an auxiliary navigation system.

[0042] The main navigation system obtains the target point's location information using the pseudorange single-point positioning method (SPP).

[0043] The auxiliary navigation system uses the location of the UWB base station as the center of a sphere and the distance between the UWB base station and the mobile station as the radius to construct a sphere; and determines a point on the sphere such that its distance to the target point is minimized. The determined point is the positioning result of the semi-compact combination method.

[0044] A navigation device: The navigation device includes the above-described UWBTOA-GNSS integrated navigation system based on semi-compact combination.

[0045] An electronic device includes a memory and a processor, the memory storing a computer program, the processor executing the computer program to implement the steps of the above method.

[0046] A computer-readable storage medium for storing computer instructions that, when executed by a processor, implement the steps of the above-described method.

[0047] Beneficial effects of the invention

[0048] This invention improves the accuracy of integrated navigation by using a semi-compact combination method, building upon the traditional UWB-OA-GNSS compact combination. Position information is obtained through pseudorange point positioning. Then, circles are drawn with the UWB position as the center and the distances from the ground truth value to the UWB and the point positioning value to the UWB as radii. The difference between the ground truth distance and the UWB value is then divided by the difference between the ground truth value and the point positioning value, effectively improving positioning accuracy.

[0049] This invention can be used in fields where GNSS signals are insufficient or where navigation accuracy needs to be enhanced. It can also be used in outdoor scenarios where GNSS navigation performance needs to be improved. It can effectively improve the accuracy of a single satellite navigation system or a traditional UWB-OA-GNSS tight combination. This invention not only further improves positioning accuracy, but also proves that even when only one UWB is working, positioning accuracy can still be greatly improved.

[0050] In a single UWB base station scenario, the UWB-TOA / GNSS single-point positioning compact combination method improves accuracy by 1.5343m compared to the GNSS single-point positioning method, representing an improvement of 28.61%. The UWB-TOA / GNSS single-point positioning semi-compact combination method improves accuracy by 2.6996m compared to the GNSS single-point positioning method, representing an improvement of 50.34%. The superior positioning accuracy of the semi-compact combination compared to the compact combination in this scenario indicates that the semi-compact combination method is superior to the compact combination method in certain situations. Attached Figure Description

[0051] Figure 1 UWB-TOA positioning error diagram;

[0052] Figure 2 A diagram showing the error of GNSS single-point positioning;

[0053] Figure 3 This is a conceptual diagram of a semi-compact combination.

[0054] Figure 4 Schematic diagram of a single UWB-TOA / GNSS single-point positioning semi-tight combination;

[0055] Figure 5 Error diagram of traditional UWB-TOA / GNSS single-point positioning tight combination;

[0056] Figure 6 Error diagram of UWB-TOA / GNSS single-point positioning integrated navigation based on semi-compact combination;

[0057] Figure 7 This is a comparison chart of the errors of semi-tight combinations and tight combinations. Detailed Implementation

[0058] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0059] Combination Figures 1 to 7 .

[0060] Pseudorange is a measured distance that includes factors such as clock errors and atmospheric refraction delays, and is not the "true distance," hence the name pseudorange. Pseudorange observations measure the distance from the phase center of the station's antenna to the phase center of the satellite, incorporating the effects of receiver and satellite clock errors, atmospheric errors (tropospheric and ionospheric), etc.

[0061] like Figure 3 The semi-compact combination is compared with other combinations as follows:

[0062] Tight combination is a method of combining the observations of the auxiliary navigation system with those of the main navigation system.

[0063] Loose combination is the combination of the results of the main navigation system and the results of the auxiliary navigation system.

[0064] Semi-tight combination is the combination of the results of the auxiliary navigation system and the observations of the main navigation system.

[0065] A UWBTOA-GNSS integrated navigation method based on semi-compact combination:

[0066] The method specifically includes the following steps:

[0067] Step 1: Obtain the target point's location information using the pseudorange single-point positioning method (SPP).

[0068] Step 2: Construct a sphere with the location of the UWB base station as the center and the distance between the UWB base station and the mobile station as the radius;

[0069] Step 3: Determine a point on the sphere described in Step 2 such that its distance from the target point in Step 1 is minimized. The determined point is the positioning result of the semi-tight combination method.

[0070] In step 1,

[0071] For all visible satellites n, pseudorange measurements ρ are collected at the same measurement time using the pseudorange point positioning method (SPP). (n) And calculate various deviation components in the measured values, such as δt. (n) I (n) and T(n) etc,

[0072] Where δt (n) Let I be the satellite clock bias of satellite n. (n) Let T be the ionospheric delay error of satellite n. (n) For satellite n, the tropospheric delay error;

[0073] According to the formula Calculate the pseudorange measurement value after error correction;

[0074] At the same time, the satellite's spatial position coordinates, corrected for Earth's rotation, are calculated based on the ephemeris of visible satellites.

[0075] The positioning error of GNSS single-point positioning is generally within 10m. With a 2m*2m deployment of 4 UWB base stations, the positioning error of UWB-TOA is generally within 1m.

[0076] However, when the number of UWB base stations is less than 4, the UWB system cannot locate. In this case, it can be combined with GNSS single-point positioning to complete the positioning.

[0077] Because the UWB-TOA method cannot provide positioning, the two systems cannot be loosely combined and can only be tightly combined to complete the positioning. Therefore, by using a semi-tight combination method, the navigation accuracy can be further improved on the basis of tight combination.

[0078] Taking a single UWB base station as an example,

[0079] The standard deviation of the ranging error between the UWB base station and the mobile station is 5 cm.

[0080] The minimum error is the distance measurement error between the point on the sphere and the actual position of the rover station.

[0081] The maximum error is the sum of twice the actual distance between the UWB base station and the mobile station and the UWB ranging error.

[0082] Draw circles with radii of the distance from the ground truth value to the UWB base station and the distance from the pseudorange point positioning value to the UWB base station, respectively. Divide the distance from the ground truth value to the UWB value and then divide the result by the difference between the ground truth value and the pseudorange point positioning value. Take the ground truth value that is closest to the pseudorange point positioning value as the positioning result.

[0083] Using the information obtained above, the nonlinear equation is linearized to obtain the matrix equation:

[0084] G[ΔxΔyΔzΔδt u ] T =b

[0085] Where [ΔxΔyΔzΔδt] u ]T G is the difference vector between the unfolded point and the receiver position and the receiver clock error result, G is the observation vector matrix between the unfolded point and each satellite, and b is the difference vector between the pseudorange and the distance between the unfolded point and the satellite.

[0086] The solution to the GPS pseudorange positioning linear matrix equation is as follows:

[0087] [ΔxΔyΔzΔδt u ] T =(G T G -1 )G T b

[0088] Update the roots of the nonlinear equation system, and update the receiver position coordinate x according to the following formula. k Clock difference δt u,k :

[0089] x k =x k-1 +Δx=x k-1 +[ΔxΔyΔz] T

[0090] δt u,k =δt u,k-1 +Δδt u .

[0091] Construct a sphere with the coordinates of the UWB base station as its center and the measured distance between the UWB base station and the mobile station as its radius:

[0092]

[0093] Among them (uwb) x uwb y uwb z P represents the three-dimensional location coordinates of the UWB base station. uwb The distance measurement value between the UWB base station and the UWB mobile station;

[0094] Find the equation of the line connecting the UWB base station and the single-point positioning result:

[0095]

[0096] Among them (spp) x ,spp y ,spp z () represents the coordinates of the single-point positioning result of the mobile station;

[0097] Solving the above two equations simultaneously yields two sets of positional solutions after semi-compact combination. Comparing the two sets of positional solutions, the distance (spp) is selected. x ,sppy ,spp z The closer location solution is used as the positioning result.

[0098] A UWBTOA-GNSS integrated navigation system based on semi-compact combination:

[0099] The navigation system includes a main navigation system and an auxiliary navigation system.

[0100] The main navigation system obtains the target point's location information using the pseudorange single-point positioning method (SPP).

[0101] The auxiliary navigation system uses the location of the UWB base station as the center of a sphere and the distance between the UWB base station and the mobile station as the radius to construct a sphere; and determines a point on the sphere such that its distance to the target point is minimized. The determined point is the positioning result of the semi-compact combination method.

[0102] A navigation device: the navigation device includes the UWBTOA-GNSS integrated navigation system based on semi-compact combination as described in claim 7.

[0103] An electronic device includes a memory and a processor, the memory storing a computer program, the processor executing the computer program to implement the steps of the above method.

[0104] A computer-readable storage medium for storing computer instructions that, when executed by a processor, implement the steps of the above-described method.

[0105] The memory in this application embodiment can be volatile memory or non-volatile memory, or it can include both volatile and non-volatile memory. The non-volatile memory can be read-only memory (ROM), programmable read-only memory (PROM), erasable programmable read-only memory (EPROM), electrically erasable programmable read-only memory (EEPROM), or flash memory. The volatile memory can be random access memory (RAM), which is used as an external cache. By way of example, but not limitation, many forms of RAM are available, such as static random access memory (SRAM), dynamic random access memory (DRAM), synchronous dynamic random access memory (SDRAM), double data rate synchronous dynamic random access memory (DDRSDRAM), enhanced synchronous dynamic random access memory (ESDRAM), synchronous linked dynamic random access memory (SLDRAM), and direct rambus RAM (DR RAM). It should be noted that the memory used in the methods described in this invention is intended to include, but is not limited to, these and any other suitable types of memory.

[0106] In the above embodiments, implementation can be achieved, in whole or in part, through software, hardware, firmware, or any combination thereof. When implemented in software, it can be implemented, in whole or in part, as a computer program product. The computer program product includes one or more computer instructions. When the computer instructions are loaded and executed on a computer, all or part of the processes or functions described in the embodiments of this application are generated. The computer can be a general-purpose computer, a special-purpose computer, a computer network, or other programmable device. The computer instructions can be stored in a computer-readable storage medium or transmitted from one computer-readable storage medium to another. For example, the computer instructions can be transmitted from one website, computer, server, or data center to another via wired (e.g., coaxial cable, fiber optic, digital subscriber line (DSL)) or wireless (e.g., infrared, wireless, microwave, etc.) means. The computer-readable storage medium can be any available medium accessible to a computer or a data storage device such as a server or data center that integrates one or more available media. The available media may be magnetic media (e.g., floppy disks, hard disks, magnetic tapes), optical media (e.g., high-density digital video discs (DVDs)), or semiconductor media (e.g., solid-state disks (SSDs)).

[0107] In implementation, each step of the above method can be completed by integrated logic circuits in the processor's hardware or by instructions in software. The steps of the method disclosed in the embodiments of this application can be directly implemented by a hardware processor, or by a combination of hardware and software modules in the processor. The software modules can reside in random access memory, flash memory, read-only memory, programmable read-only memory, electrically erasable programmable memory, registers, or other mature storage media in the art. This storage medium is located in memory, and the processor reads information from the memory and, in conjunction with its hardware, completes the steps of the above method. To avoid repetition, detailed descriptions are omitted here.

[0108] It should be noted that the processor in the embodiments of this application can be an integrated circuit chip with signal processing capabilities. During implementation, each step of the above method embodiments can be completed by the integrated logic circuits in the processor's hardware or by instructions in software form. The processor can be a general-purpose processor, a digital signal processor (DSP), an application-specific integrated circuit (ASIC), a field-programmable gate array (FPGA), or other programmable logic devices, discrete gate or transistor logic devices, or discrete hardware components. It can implement or execute the methods, steps, and logic block diagrams disclosed in the embodiments of this application. The general-purpose processor can be a microprocessor or any conventional processor. The steps of the methods disclosed in the embodiments of this application can be directly embodied as being executed by a hardware decoding processor, or executed by a combination of hardware and software modules in the decoding processor. The software modules can be located in random access memory, flash memory, read-only memory, programmable read-only memory, electrically erasable programmable memory, registers, or other mature storage media in the art. This storage medium is located in memory, and the processor reads the information in the memory and, in conjunction with its hardware, completes the steps of the above methods.

[0109] The foregoing has provided a detailed description of the UWBTOA-GNSS integrated navigation system and method based on semi-compact combination proposed in this invention, and has elucidated the principles and implementation methods of this invention. The description of the above embodiments is only for the purpose of helping to understand the method and core ideas of this invention. At the same time, for those skilled in the art, there will be changes in the specific implementation methods and application scope based on the ideas of this invention. Therefore, the content of this specification should not be construed as a limitation of this invention.

Claims

1. A method for UWB TOA-GNSS integrated navigation based on semi-tight combination, characterized in that: The method specifically comprises the following steps: Step 1: obtaining the position information of the target point by the pseudo-range single point positioning method SPP; Step 2: taking the position of the UWB base station as the center of a sphere and the distance between the UWB base station and the mobile station as the radius of the sphere; ， wherein is a three-dimensional position coordinate of the UWB base station, is a ranging value between the UWB base station and the UWB mobile station; Step 3: determining a point on the sphere in step 2 such that the distance from the point to the target point in step 1 is minimized, and the determined point is the positioning result of the semi-tight combination method; obtaining the equation of the straight line on which the single point positioning result lies: ， wherein is the single point positioning result coordinate of the mobile station; Solving the above two equations simultaneously, we get two sets of position solutions after semi-tight combination, compare the two sets of position solutions, select the set of position solutions closer to the positioning result.

2. The navigation method of claim 1, wherein: In step 1, For all visible satellites , pseudorange measurements at the same measurement time are collected by the pseudorange single point positioning method SPP , and various bias components in the measurements are calculated , and , wherein is a satellite clock error, is an ionospheric delay error, is a tropospheric delay error, and is a tropospheric delay error.​​ According to the formula calculating the pseudorange measurement after error correction; Meanwhile, the satellite spatial position coordinates after the earth rotation correction are calculated according to the ephemeris of the visible satellites. 3.The method according to claim 2, characterized in that: the standard deviation of the ranging error between the UWB base station and the mobile station is 5 cm; the minimum error is the ranging error of the point on the sphere and the real position of the mobile station, the maximum error is the sum of the real distance between the UWB base station and the mobile station and twice the UWB ranging error. 4.The method according to claim 3, characterized in that: by means of the information obtained above, the non-linear equation is linearized to obtain a matrix equation: wherein is a difference vector between the deployment point and the receiver position, the receiver clock bias result, is an observation vector matrix between the deployment point and each satellite, is a difference vector between the pseudorange and the distance between the deployment point and the satellite. the least square method is used to solve the linear matrix equation of the GPS pseudo-range positioning, and the solution is: updating the roots of the nonlinear equations, updating the receiver position coordinates according to the following equation and the clock difference value :

5. A semi-closed combination based UWB TOA-GNSS integrated navigation system, characterized in that: The system is used to execute the integrated navigation method according to any one of claims 1 to 4, The navigation system comprises a main navigation system and an auxiliary navigation system The main navigation system obtains the position information of the target point by the pseudo-range single point positioning method SPP; The auxiliary navigation system takes the position of the UWB base station as the center of a sphere and the distance between the UWB base station and the mobile station as the radius of the sphere, and determines a point on the sphere such that the distance from the point to the target point is minimized, and the determined point is the positioning result of the semi-tight combination method.

6. A navigation device characterized by: The navigation device comprises the UWB TOA-GNSS integrated navigation system based on semi-tight combination according to claim 5. 7.An electronic device comprising a memory and a processor, the memory storing a computer program, wherein, The processor executes the computer program to realize the steps of the method according to any one of claims 1 to 4.

8. A computer readable storage medium for storing computer instructions, characterized in that, The computer instructions are executed by the processor to realize the steps of the method according to any one of claims 1 to 4.

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