CN108008426B - Pseudolite based positioning system and method - Google Patents
Pseudolite based positioning system and method Download PDFInfo
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- CN108008426B CN108008426B CN201610944206.9A CN201610944206A CN108008426B CN 108008426 B CN108008426 B CN 108008426B CN 201610944206 A CN201610944206 A CN 201610944206A CN 108008426 B CN108008426 B CN 108008426B
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- G—PHYSICS
- G01—MEASURING; TESTING
- G01S—RADIO DIRECTION-FINDING; RADIO NAVIGATION; DETERMINING DISTANCE OR VELOCITY BY USE OF RADIO WAVES; LOCATING OR PRESENCE-DETECTING BY USE OF THE REFLECTION OR RERADIATION OF RADIO WAVES; ANALOGOUS ARRANGEMENTS USING OTHER WAVES
- G01S19/00—Satellite radio beacon positioning systems; Determining position, velocity or attitude using signals transmitted by such systems
- G01S19/38—Determining a navigation solution using signals transmitted by a satellite radio beacon positioning system
- G01S19/39—Determining a navigation solution using signals transmitted by a satellite radio beacon positioning system the satellite radio beacon positioning system transmitting time-stamped messages, e.g. GPS [Global Positioning System], GLONASS [Global Orbiting Navigation Satellite System] or GALILEO
- G01S19/42—Determining position
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- G—PHYSICS
- G01—MEASURING; TESTING
- G01S—RADIO DIRECTION-FINDING; RADIO NAVIGATION; DETERMINING DISTANCE OR VELOCITY BY USE OF RADIO WAVES; LOCATING OR PRESENCE-DETECTING BY USE OF THE REFLECTION OR RERADIATION OF RADIO WAVES; ANALOGOUS ARRANGEMENTS USING OTHER WAVES
- G01S19/00—Satellite radio beacon positioning systems; Determining position, velocity or attitude using signals transmitted by such systems
- G01S19/01—Satellite radio beacon positioning systems transmitting time-stamped messages, e.g. GPS [Global Positioning System], GLONASS [Global Orbiting Navigation Satellite System] or GALILEO
- G01S19/03—Cooperating elements; Interaction or communication between different cooperating elements or between cooperating elements and receivers
- G01S19/10—Cooperating elements; Interaction or communication between different cooperating elements or between cooperating elements and receivers providing dedicated supplementary positioning signals
- G01S19/11—Cooperating elements; Interaction or communication between different cooperating elements or between cooperating elements and receivers providing dedicated supplementary positioning signals wherein the cooperating elements are pseudolites or satellite radio beacon positioning system signal repeaters
Abstract
Pseudolite based positioning systems and methods are disclosed. A pseudolite based positioning system according to the present application, comprising: each pseudolite simulates a satellite signal of a satellite and sends the simulated satellite signal according to the satellite parameters, the pseudolite position and the reference time delay; and a terminal including: a receiver for determining an initial position estimate of the terminal from received simulated satellite signals; a processor configured to obtain a pseudo-satellite pseudo-range estimate between a terminal and a pseudo-satellite based on the initial position estimate and the reference time delay to determine an accurate position estimate for the terminal. By the pseudo-satellite-based positioning system and method, accurate position estimation of the user terminal can be obtained.
Description
Technical Field
The present application relates to pseudolite based positioning systems and methods.
Background
Global Navigation Satellite Systems (GNSS) can provide all-weather, uninterrupted and high-precision real-time positioning, Navigation and time service information, and a wide and effective GNSS application technology has penetrated into various fields of modern society and becomes an important resource for supporting national economy and guaranteeing national safety. The effectiveness of a GNSS system depends on the spatial constellation of the GNSS and the coverage of different satellite signals. Although GNSS can continuously provide accurate and effective navigation information in most outdoor environments, in indoor environments and in urban canyons and other areas, GNSS signals may be blocked by buildings, so that the number of visible satellites is reduced, and GNSS service and application are greatly limited. However, just the population and buildings of a city, which is a widely used area of GNSS, are dense, and thus guaranteeing the excellent performance of GNSS in these environments is a key factor for improving the level of satellite navigation services.
There are many positioning technologies such as Wireless Local Area Network (WLAN) and Wireless Personal Area Network (WPAN) positioning technologies, Universal Mobile Telecommunications System (UMTS), inertial navigation system, laser, infrared positioning technologies, and ultrasonic positioning, etc. Despite the advantages of each of these techniques, the accuracy is difficult to match with GNSS and is not mature enough. Moreover, in indoor and outdoor mixed scenes, the technologies are difficult to implement seamless connection with GNSS, and thus the good performance and the advantages of GNSS in most scenes cannot be effectively utilized.
The pseudolite positioning technology is an important means for making up the defects of the GNSS, and the geometric distribution of the satellites can be artificially improved by installing the pseudolites. Pseudolite technology has significant application in areas where GNSS satellites are poorly visible. An existing pseudolite positioning technology broadcasts a navigation signal designed for a pseudolite through the pseudolite, the carrier frequency, the pseudocode and the ephemeris format adopted by the pseudolite can be different from those of a GNSS, and a receiver designed for the pseudolite signal is used for capturing the pseudolite signal to realize navigation positioning. However, this pseudolite positioning technique requires modifications to the GNSS receiver hardware and software and is therefore not suitable in many scenarios.
Another conventional pseudolite positioning technique is to broadcast a virtual GNSS signal via a pseudolite, where carrier frequency, pseudocode design, and textual format of the pseudolite completely refer to the GNSS signal to virtualize a GNSS satellite located on the sky, and a GNSS receiver can directly capture the pseudolite signal and complete positioning through some subsequent processing. However, since the pseudolites, although they virtualize GNSS signals, cannot directly provide accurate pseudorange information, the receiver cannot directly resolve the correct position. So far, no good method exists for performing corresponding processing to obtain the accurate position of the receiver, so that the pseudolite positioning technology can only be mainly applied to scenes such as spoofing and the like.
Disclosure of Invention
It is an object of the present application to provide a pseudolite based positioning system and method that enables accurate position estimates of user terminals to be obtained.
According to an aspect of the present application, there is provided a pseudolite based positioning system comprising: each pseudolite simulates a satellite signal of a satellite and sends the simulated satellite signal according to the satellite parameters, the pseudolite position and the reference time delay; and a terminal including: a receiver for determining an initial position estimate of the terminal from received simulated satellite signals; a processor configured to obtain a pseudo-satellite pseudo-range estimate between a terminal and a pseudo-satellite based on the initial position estimate and the reference time delay to determine an accurate position estimate for the terminal.
According to another aspect of the present application, there is provided a pseudolite based positioning method comprising: simulating satellite signals of the satellites and sending the simulated satellite signals through each pseudolite in the pseudolites according to the satellite parameters, the pseudolite positions and the reference time delay; receiving the simulated satellite signals, and determining initial position estimation of the user terminal according to the received simulated satellite signals; and obtaining a pseudo-satellite pseudo-range estimation value between the user terminal and the pseudo-satellite according to the initial position estimation and the reference time delay so as to determine the accurate position estimation of the user terminal.
According to another aspect of the present application, there is also provided a pseudolite based positioning system comprising: the receiving device receives satellite signals from a plurality of satellites, and obtains satellite parameters of each satellite and transmission time delay of the satellite signals from each satellite to the receiving device; each pseudolite regenerates the satellite signal of one satellite of the pseudolites according to the satellite parameter of the satellite and the transmission delay of the satellite signal from the satellite to a receiving device, and forwards the regenerated satellite signal; and a terminal including: a receiver for determining an initial position estimate of the terminal based on the received forwarded satellite signals; and a processor for obtaining a pseudo-satellite pseudo-range estimate between the terminal and the pseudo-satellite based on the initial position estimate, the satellite parameters of the satellite, the pseudo-satellite position, and the propagation delay of the satellite signal from the satellite to the receiving device to determine an accurate position estimate for the terminal.
According to another aspect of the present application, there is also provided a pseudolite-based positioning method, comprising: receiving satellite signals from a plurality of satellites, and obtaining satellite parameters of each satellite and transmission time delay from the transmission to the reception of each satellite; regenerating the satellite signal of one of the plurality of pseudolites according to the satellite parameter of the satellite and the transmission delay from the satellite to the satellite signal, and forwarding the regenerated satellite signal; receiving the forwarded satellite signals, and determining initial position estimation of the user terminal according to the received forwarded satellite signals; and obtaining a pseudo-satellite pseudo-range estimation value between the terminal and the pseudo-satellite according to the initial position estimation, the satellite parameters of the satellite, the pseudo-satellite position and the transmission delay from the satellite to the satellite so as to determine the accurate position estimation of the user terminal.
It will be appreciated that accurate position estimates for user terminals can be obtained by the pseudolite based positioning system and method disclosed herein. In addition, according to the pseudo satellite positioning system and method, the traditional GNSS receiver can be adopted to directly capture satellite signals simulated or forwarded by pseudo satellites for positioning and resolving, and software and hardware modification of the traditional GNSS receiver is not needed, so that seamless connection with the GNSS can be realized. In addition, according to the pseudolite positioning system and the pseudolite positioning method, the positioning calculation result of the traditional receiver can be corrected, and accurate position estimation can be obtained.
Drawings
FIG. 1 shows a schematic diagram of a pseudolite based positioning system according to an embodiment of the present application.
Figure 2 shows a schematic block diagram of a user terminal of a pseudolite positioning system according to an embodiment of the present application.
Figure 3 shows a schematic diagram of a pseudolite based positioning system according to another embodiment of the present application.
Figure 4 shows a schematic block diagram of a user terminal of a pseudolite positioning system according to another embodiment of the present application.
Figure 5 shows a schematic diagram of a pseudolite based positioning system according to another embodiment of the present application.
Detailed Description
The pseudolite based positioning system and method disclosed in the present application is described in detail below with reference to the accompanying drawings. For the sake of simplicity, the same or similar reference numerals are used for the same or similar devices in the description of the embodiments of the present application.
FIG. 1 shows a schematic diagram of a pseudolite based positioning system according to an embodiment of the present application. As shown, the pseudolite positioning system 10 includes a plurality of pseudolites 100(100-1, 100-2, 100-3, 100-4) and a terminal 200. In the pseudolite system, each of a plurality of pseudolites 100 simulates a satellite signal of a satellite S100(S100-1, S100-2, S100-3, S100-4) and transmits the simulated satellite signal according to a satellite parameter, a pseudolite position and a reference delay. For example, the pseudolite 100 may simulate a GNSS satellite signal, such as a GPS signal or a beidou signal, and broadcast the simulated satellite signal to the user via a radio frequency antenna. It will be appreciated that in a pseudolite positioning system, the pseudolite locations are known. The simulated satellite S100 may be a real existing satellite or a virtual satellite.
Further, referring again to fig. 1, according to another aspect of the present application, there is also provided a pseudolite-based positioning method, including: simulating satellite signals of the satellites and sending the simulated satellite signals through each pseudolite in the pseudolites according to the satellite parameters, the pseudolite positions and the reference time delay; receiving simulated satellite signals, and determining initial position estimation of a user terminal according to the received simulated satellite signals; and obtaining a pseudolite pseudo range estimate between the user terminal and the pseudolite based on the initial position estimate and the reference time delay to determine an accurate position estimate for the user terminal.
Figure 2 shows a schematic block diagram of a user terminal of a pseudolite positioning system according to an embodiment of the present application. As shown, the user terminal 200 includes a receiver 210 and a processor 220. The receiver 210 may use a conventional GNSS receiver to directly process the received simulated satellite signals, perform positioning calculation according to the received simulated satellite signals, and determine an initial position estimate of the terminal. Processor 220 obtains pseudolite pseudorange estimates between the terminal and the pseudolites based on the initial position estimate and the reference time delay to enable further determination of an accurate position estimate for the terminal. For example, processor 220 may determine a simulated satellite pseudorange estimate between the terminal and the simulated satellite based on the initial position estimate and the simulated satellite parameters, and a pseudolite pseudorange estimate between the terminal and the pseudolite based on the simulated satellite pseudorange estimate and the reference time delay, thereby enabling a further determination of an accurate position estimate for the terminal.
It can be understood that, by the above positioning system and method based on the pseudolite, the receiver 210 can directly capture the satellite signals simulated by the pseudolite by using the conventional GNSS receiver to perform positioning calculation, so as to obtain accurate position estimation, without modifying software and hardware of the conventional GNSS receiver, thereby achieving seamless connection with the GNSS.
In addition, since the receiver 210 can receive both the satellite signals simulated by the pseudolites and the real GNSS satellite signals, the pseudolite system and the method according to the present application can perform navigation and positioning by using a plurality of pseudolites alone, or can perform navigation and positioning by using a combination of the pseudolites and the GNSS satellites. Therefore, the pseudo satellite positioning system and the pseudo satellite positioning method can be compatible with a GNSS system, can increase the number of visible satellites by utilizing pseudo satellite virtual GNSS signals in the GNSS system, and improve the constellation distribution of the visible satellites, thereby realizing effective positioning and achieving higher positioning precision.
Although 4 pseudolites are shown in FIG. 1 as simulating 4 GNSS satellites, those skilled in the art will appreciate that the number of pseudolites in a pseudolite-based positioning system according to the present application is not limited to 4. If a plurality of pseudolites are independently utilized for navigation and positioning, more than 4 pseudolites are needed for positioning. The number of pseudolites may be smaller if the combined pseudolite and GNSS satellite is used to achieve a navigational fix.
According to one embodiment, the satellite parameters are satellite-related parameters, which may include, for example, ephemeris information and pseudorandom codes. The satellite parameters may also include doppler information, power information, and the like. Pseudo-random codes are used to distinguish between different satellite signals. Ephemeris information typically includes satellite clock data, kepler orbit parameters, almanac, and ionospheric delay correction parameters, etc. for accurately calculating the spatial position and velocity of the satellite at each time.
Figure 3 shows a schematic diagram of a pseudolite based positioning system according to another embodiment of the present application. As shown in fig. 3, the pseudolite system may also include a data center 300 to store and provide satellite parameters. Figure 4 shows a schematic block diagram of a user terminal of a pseudolite positioning system according to another embodiment of the present application. As shown in fig. 4, the terminal 200 may further include a communication module 230 to communicate with the data center 300 to obtain satellite parameters. Alternatively, the pseudolite system may not include a data center and a communication module, and the satellite parameters are stored by the processor 220 of the terminal 200.
Since the pseudolite simulates satellite signals of satellites, in order to enable the existing GNSS receiver 210 in the user terminal 200 to process the simulated satellite signals without modification and obtain accurate positioning solution, a reference time delay needs to be added to the generated simulated signals so that the pseudorange acquired by the receiver 210 is equivalent to the pseudorange of a real satellite.
For the user receiver 210, it receives signals from pseudolites, but the receiver 210 will "think" that the signals are from real GNSS satellites and will compute the positions of the simulated GNSS satellites using the simulated GNSS satellite orbit parameters broadcast in the received satellite ephemeris for use in position solution. Since the distance between the pseudolite 100 and the user terminal 200 and the distance between the pseudolite S100 and the user terminal 200 are very different, the receiver will get a wrong position estimate through the solution process if no time delay processing is performed. The pseudolite 100, when emulating the GNSS satellite S100, therefore adds a reference delay to the generated signal to ensure that the pseudorange measurements acquired by the receiver 210 are approximately equal to the distance between the receiver 210 and the emulated GNSS satellite S100.
According to one embodiment, the reference time delay may be set according to the coverage of the pseudolite. Referring again to FIG. 3, for example, a reference point R1 may be selected within the pseudolite coverage area, and a reference time delay may be determined based on the simulated satellite parameters, the pseudolite location, and the location of the reference point. The reference time delay of a pseudolite signal may be set such that a pseudorange measurement obtained by a receiver at a reference point is equal to the distance of the receiver from the satellite for which the pseudolite is a virtual satellite.
For example, for a pseudolite near the surface, the position vector is x(p)＝(x(p),y(p),z(p)) The position vector of the pseudolite is
Where the symbol "" indicates that the parameter or vector is a virtual quantity. The reference time delay set by the signal of the pseudolite is tau. When the reference point R1 is adopted, the reference time delay τ may be set to:
wherein
The position vector representing the reference point, I, T, e, these error terms model the ionosphere, troposphere, and star clock error terms of the virtual satellite so that existing receivers can automatically eliminate them.
According to one embodiment, the setting of the reference time delay may be performed by the processor 220 of the terminal 200. Alternatively, the setting of the reference delay may be performed by the data center 300, and the data center 300 provides the reference delay parameter to the communication module 230 of the terminal 200. Thus, by setting the reference time delay, the validity of the receiver position estimation can be ensured.
However, since the reference time delay τ is set by the pseudolite and is not equal to the actual time delay of the user location received signal, e.g., the location of the reference point R1 is not usually exactly the same as the actual location of the user terminal 200, the pseudorange measurements obtained by the receiver 210 through the reception of the virtual satellite signals will deviate from the true pseudoranges, which will also cause the receiver 210 to obtain initial position estimates using the pseudorange measurements and the simulated satellite position solution
There is a deviation. That is, although the receiver can directly obtain the initial position by using the pseudolite signalThe initial position estimate is often inaccurate, requiring an initial position estimate
Corrections are made to obtain an accurate position estimate.
The pseudolite positioning system and method according to embodiments of the present application are described in detail below in conjunction with a signal model of a pseudolite.
For a true GNSS satellite system, the receiver is at t according to the pseudo-range measurement principleuGNSS signal pseudo range rho received at moment(s)Can be expressed as:
ρ(s)＝||x(s)-x(u)||+c(δtu-δt(s))+I+T+e，
where δ tuAnd δ t(s)Respectively representing receiver clock error and satellite clock error, I, T representing virtual satellite ionosphere and troposphere error terms, and e representing noise. Typically, δ t is corrected after the pseudoranges are corrected according to the parameters in the ephemeris(s)I, T may be known quantities, whereas in a true GNSS satellite system the noise e is typically relatively small.
The corrected pseudorange equation can thus be obtained as follows:
ρ(s)＝||x(s)-x(u)||+B+e，
wherein B is a reduced clock error term. According to the pseudo-range positioning principle, when the receiver obtains at least 4 satellite signals, the position of the receiver can be obtained through calculation.
For a pseudolite system, the receiver 210 obtains simulated satellite pseudorange measurements due to the simulation of the satellite signals of satellite S100 by pseudolite 100
And user terminal x(u)And the position x of the pseudolite(p)And reference delay τ -related:
since the receiver does not "know" about the presence of pseudolites and the reference time delay τ, for the receiver 210, the receiver will have pseudorange measurements from each of the simulated satellites during the positioning process
"seeing" is user location information
Sum and clock error information BfakeSo that a simulated satellite pseudorange equation can be constructed:
in the above equation, the position of the satellite is simulated
The pseudo-range can be calculated according to satellite ephemeris data sent by a pseudo-satellite, the pseudo-range of a simulated satellite is measured by a receiver, and the three-dimensional position component of the receiver and the clock error of the receiver in an equation set are unknown quantities. The receiver receives the simulated satellite signals from more than 4 pseudo satellites, at least 4 pseudo-range equations of the simulated satellites are established, the unknown quantity in the equations can be solved, and the receiver clock error B is obtainedfakeAnd initial position estimation
E represents the initial position estimate of the position estimate convergence value when solving the pseudo-range equation of the analog satellite
The latter residual error, also called pseudorange residual. Since the receiver clock offset is not a concern for the present application and is corrected concurrently with the correction of the initial position estimate, the receiver clock offset will not be described in detail in the following description.
As described above, the initial position estimate
Often inaccurate, and need to be estimated by estimating the initial position
And correcting to obtain accurate position estimation.
According to an embodiment of the present application, the processor 220 may estimate the initial position based on the initial position
And simulating the position of the satellite
Determining a pseudo-range estimate for a simulated satellite between a terminal and a simulated GNSS satellite
Where the symbol "a" indicates that the parameter or vector is an estimate. Wherein the position of the satellite is simulated
Ephemeris information of the GNSS satellites may be obtained.
May be estimated from pseudolite pseudorangesValue of
And pseudolite position x(p)Establishing a pseudo range equation of the pseudo satellite:
due to estimation based on the initial position
Pseudo-range estimation value of pseudo satellite can be obtained
Thus incorporating pseudolite position x(p)The pseudo-range positioning principle can be utilized to perform positioning calculation again, so that the initial position estimation of the receiver is corrected, and the corrected receiver position estimation is obtained.
However, in a pseudolite positioning system, since the pseudo-range measurements of the simulated satellites are not real pseudo-ranges but are related to the relative positions of the pseudolites and the receiver and the reference time delay, i.e. there is a deviation between the pseudo-range measurements and the real pseudo-ranges, the simulated satellite positions for the solution and the corresponding simulated satellite pseudo-range measurements do not satisfy the simulated satellite pseudo-range equations, so that the simulated satellite pseudo-range equations are not self-consistent, which on the one hand will result in initial position estimates
Incorrect, on the other hand, will cause the positioning to converge to the initial position estimate despite
The simulated satellite pseudorange residuals at convergence, e, will still be relatively large.
In the subsequent process of correcting the initial position estimation, the larger simulated satellite pseudo-range residual belongs to the range of pseudo-range estimation values of subsequently obtained pseudolites
The estimation error of (2) is large, thereby affecting the accuracy in the initial position estimation correction. Thus, in prior art GNSS systems, small residuals, which are not normally considered and cannot be eliminated, need to be considered to obtain an accurate position estimate, since in pseudolite systems, the simulated satellite pseudorange equations are not self-consistent and become larger pseudorange residuals e.
The influence of the simulated satellite pseudorange residuals e on the subsequent initial position estimation correction process is specifically analyzed below. According to the application, pseudo-range measurements of simulated satellites received by a receiver
And simulated satellite pseudorange estimates
Can be respectively expressed as:
it can be seen that
Further, according to the present application, satellite pseudorange measurements are simulated
May also be denoted as user terminal x(u)And the position x of the pseudolite(p)And the way in which the reference delay τ is related:
since the error e is relatively small and negligible, therefore,
thus, pseudo-range estimates are based on simulated satellites
And pseudo-satellite pseudo-range estimates determined with reference to the time delay tau
Can be expressed as:
considering pseudolite true pseudoranges p(p)To be expressed as:
ρ(p)＝||x(p)-x(u)||+B，
thus, according to the present application, pseudo-range estimates are obtained by simulating satellites
Recovering the pseudo-range estimation value of the obtained pseudolite
True pseudorange p to pseudolite(p)The error between is:
it can be seen that the error in the recovered pseudolite pseudorange estimates is exactly the pseudorange residual e for the simulated GNSS satellites. Therefore, according to an embodiment of the present application, the initial position estimate may be modified by jointly simulating a satellite pseudorange residual constraint and a pseudolite pseudorange equation, thereby achieving an accurate estimate of the user position.
In fact, although the initial positioning process of the receiver obtains an incorrect initial position estimate, the initial position estimate is still the best estimate for the receiver to satisfy the simulated satellite pseudorange equations as much as possible. Therefore, according to one embodiment of the present application, the simulated satellite pseudorange residual constraints include a constraint that the pseudorange residuals satisfy a norm minimum.
The pseudo-range residual constraint condition of the simulated satellite is explained in detail below by combining a specific positioning resolving process of a pseudo-range equation of the simulated satellite.
When the receiver performs positioning solution according to the pseudo-range equation of the simulated satellite, a nonlinear method is generally adopted for solution, for example, least square iteration solution is adopted. The following description will be given taking the least squares iterative solution as an example. Firstly, the current position of the receiver and the initial estimated value of the clock difference are given
And (3) carrying out Taylor expansion on the equation at the estimated position, and neglecting terms with more than two orders to realize nonlinear equation linearization:
wherein the following can be obtained through calculation:
the system of equations can thus be approximately converted into the following form:
wherein:
wherein the content of the first and second substances,
the pseudorange residuals representing the current estimated position, G represents the observation matrix between the current estimated position and the simulated satellites, and δ x represents the amount of update to the current estimated position.
Therefore, the least squares iterative update amount that reduces the sum of the pseudo-range equation mean square errors is:
the iterative equation for the position estimate is then:
and updating the solution of the nonlinear equation set according to the above, taking the updated position as a new iteration starting point, and continuing the above iteration operation until the obtained solution is converged, thereby obtaining the position estimation of the receiver. That is, the receiver initial position estimate can be obtained when the iterations converge:
furthermore, when the iteration converges, taking the limit on the iterative equation for the position estimate may result in:
thereby further obtaining:
here, the observation matrix at the time of iterative convergence is described as
Namely:
when the iterations converge
Then the pseudorange residuals e are indicated.
It can be found that there is an orthogonal relationship between the corresponding observation matrix and the simulated satellite pseudorange residuals when the iteration converges to the initial position estimate, i.e. the pseudorange residuals satisfy the norm minimum constraint:
wherein
An observation matrix representing the initial position estimate and the positions of the simulated satellites may be expressed as:
and after the pseudo-range residual constraint is obtained, a pseudo-satellite pseudo-range equation is constructed according to the pseudo-satellite pseudo-range estimation value and the pseudo-satellite position, the pseudo-satellite pseudo-range equation and the pseudo-range residual constraint are combined, the initial position estimation is corrected, and the accurate position estimation of the terminal is determined.
Constructing a pseudo-satellite pseudo-range equation according to the pseudo-satellite pseudo-range estimation value and the pseudo-satellite position, wherein the pseudo-satellite pseudo-range equation is expressed as follows:
combining the pseudo-range residual constraint conditions:
an accurate position estimate for the receiver is iteratively calculated using a simultaneous system of equations. The iterative algorithm may be, for example, a least squares solution, and uses the initial position estimate pseudorange residuals and the initial position estimate observation matrix orthogonality characteristics, and weights the initial observation matrix in an iterative process, so as to eliminate the iterative influence of the residuals. And continuing iteration until the result is converged, and obtaining the accurate position estimation of the receiver.
In the solution of the simultaneous system of equations, a nonlinear method, such as one of iterative least squares, levenberg-marquardt method, gauss-newton method, and maximum likelihood method, may be generally used to perform the solution. However, since the pseudolite is closer to the receiver, the non-linear error that is negligible for GNSS satellites that are further away may affect the positioning accuracy of the pseudolite system and method, and may even cause the solution result to be non-convergent.
According to one embodiment of the application, a non-linear error in positioning can be estimated, and when the non-linear error is smaller than a predetermined threshold, the positioning calculation result is considered to be convergent; when the non-linear error is larger than the threshold value, the re-solution may be performed, for example, another non-linear method different from the non-linear method used in the current pseudorange equation solution may be selected for the positioning re-solution.
For example, the positioning non-linearity error can be estimated using a standard deviation decision criterion:
the above several non-linear model errors are estimated by using the above formula, and a threshold (for example, may be set to 1) is set, that is, the decision criterion is:
wherein the content of the first and second substances,
where the observation y may be expressed as a non-linear function y ═ f (x) of the receiver position x, determined by the non-linear method used in solving the pseudorange equations,
which represents an estimate of the position of the receiver,
representing deviation, Q, of receiver position estimateyAnd QyyRespectively representing the mean and variance of the observed quantity y.
In the embodiments described above, in the pseudolite positioning system and method, positioning is performed by pseudolites simulating satellite signals of satellites and transmitting the simulated satellite signals. According to another aspect of the present application, the pseudolite may not necessarily simulate a satellite signal, but may receive a satellite signal from a GNSS satellite through the pseudolite and regeneratively retransmit the satellite signal for positioning.
According to one embodiment of the present application, as shown in FIG. 5, a pseudolite based pseudolite system 10 'includes a receiving device 110', a plurality of pseudolites 100'(100-1', 100-2', 100-3', 100-4') and a terminal 200'.
The receiving device 110' receives satellite signals from a plurality of GNSS satellites S100' (S100-1', S100-2', S100-3', S100-4'), and obtains satellite parameters of each satellite and a propagation delay of the satellite signal from each satellite to the receiving device 110 '.
Each pseudolite of the plurality of pseudolites 100' regenerates the satellite signal of one of the plurality of satellites based on the satellite parameters of the satellite and the propagation delay of the satellite signal from the one satellite to the receiving device and forwards the regenerated satellite signal.
The user terminal 200' includes a receiver 210' and a processor 220 '. The receiver 210 'may employ a conventional GNSS receiver to determine an initial position estimate for the terminal based on the received satellite signals relayed by the pseudolite 100'. The processor 220' obtains pseudolite pseudorange estimates between the terminal and the pseudolites based on the initial position estimate, the satellite parameters of the satellites, the pseudolite positions, and the propagation delays of the satellite signals from the satellites to the receiving device to determine an accurate position estimate for the terminal. The satellite parameters of the relay satellite comprise ephemeris information and pseudo-random codes of the GNSS satellite.
Further, referring again to fig. 5, according to another aspect of the present application, there is also provided a pseudolite-based positioning method including: receiving satellite signals from a plurality of satellites, and obtaining satellite parameters of each satellite and transmission time delay from the transmission to the reception of each satellite; regenerating the satellite signal of a certain satellite of the plurality of satellites according to the satellite parameter of the satellite and the transmission delay from the satellite signal to the satellite signal through each pseudolite of the plurality of pseudolites, and forwarding the regenerated satellite signal; (ii) a Receiving the forwarded satellite signals, and determining initial position estimation of the user terminal according to the received forwarded satellite signals; and obtaining a pseudolite pseudo range estimate between the terminal and the pseudolite based on the initial position estimate, the satellite parameters of the satellite, the pseudolite position, and the propagation delay from transmission to reception of the satellite signal to determine an accurate position estimate for the user terminal.
According to one embodiment, processor 220' may obtain a forward satellite pseudorange residual constraint based on an initial position estimate determined by the receiver, construct a pseudolite pseudorange equation based on the pseudolite pseudorange estimate and the pseudolite position, and combine the pseudolite pseudorange equation with the forward satellite pseudorange residual constraint to determine an accurate position estimate for the terminal. And the constraint of the forwarded satellite pseudo-range residual errors comprises the constraint condition that the pseudo-range residual errors meet the minimum norm. For example, the forwarded satellite pseudorange residuals satisfying a norm minimum constraint include:
wherein the content of the first and second substances,
representing views between initial position estimates and positions of transponded satellitesThe measurement matrix,. epsilon.represents the pseudorange residuals, wherein the position of the transponded satellite is determined from the satellite parameters of the satellite.
According to one embodiment, the processor 220' may determine a transponded satellite pseudorange estimate between the terminal and the transponded satellite based on the initial position estimate and the satellite parameters of the transponded satellite; and determining a pseudo-satellite pseudo-range estimated value between the terminal and the pseudo-satellite according to the pseudo-range estimated value of the forwarding satellite and the transmission time delay.
According to one embodiment, the pseudolite system 10' may further include a data center that provides satellite parameters for each satellite acquired by the receiving device and a propagation delay of the satellite signal from each satellite to the receiving device. The terminal 200' may further include a communication module that receives satellite parameters and a transfer delay provided by the data center.
According to an embodiment, the processor 220' of the terminal may further estimate a non-linear error in the process of calculating the accurate position estimation of the terminal, and when the non-linear error is smaller than a predetermined threshold, it is determined that the calculation result is correct; and when the nonlinear error is larger than the threshold value, performing re-calculation.
According to one embodiment, the receiver 210 'of the terminal may also receive satellite signals from one or more satellites, and the receiver 210' determines an initial position estimate for the terminal based on the forwarded satellite signals in combination with the satellite signals from the satellites.
Therefore, the pseudo satellite positioning system and method realized by adopting the mode of forwarding the satellite signal do not need to set reference time delay, but can calculate and obtain the transmission time delay of the satellite signal from the satellite to the receiving device. In a specific positioning calculation process, the transmission delay has the same function as the reference delay. It can be understood that the user terminal part of the pseudolite positioning system and method implemented by adopting the satellite signal forwarding mode according to the application is basically consistent with the user terminal part of the pseudolite positioning system and method implemented by adopting the simulated satellite signal mode according to the application except that the reference time delay is not required to be set and the positioning calculation is carried out by utilizing the transmission time delay. Therefore, the similar embodiments as those in the pseudo satellite positioning system and method implemented by using analog satellite signals will not be described herein.
Exemplary embodiments of the present application are described above with reference to the accompanying drawings. It will be appreciated by those skilled in the art that the above-described embodiments are merely exemplary for purposes of illustration and are not intended to be limiting, and that any modifications, equivalents, etc. that fall within the teachings of this application and the scope of the claims should be construed to be covered thereby.
Claims (32)
1. A pseudolite based positioning system comprising:
each pseudolite simulates a satellite signal of a satellite and sends the simulated satellite signal according to the satellite parameters, the pseudolite position and the reference time delay; and
a terminal, comprising:
a receiver for determining an initial position estimate of the terminal from received simulated satellite signals; and
a processor for obtaining a pseudolite pseudorange estimate between a terminal and a pseudolite based on the initial position estimate and the reference time delay to determine an accurate position estimate for the terminal,
the processor obtains a pseudo-range residual constraint of a simulated satellite according to the initial position estimation determined by the receiver, constructs a pseudo-range equation of the pseudo-satellite according to the pseudo-range estimation value of the pseudo-satellite and the pseudo-satellite position, and determines the accurate position estimation of the terminal by combining the pseudo-range equation of the pseudo-satellite and the pseudo-range residual constraint of the simulated satellite.
2. The positioning system of claim 1, wherein the simulated satellite pseudorange residual constraints include a pseudorange residual satisfying a norm minimum constraint.
3. The positioning system of claim 2, wherein the simulated satellite pseudorange residuals satisfying a norm minimum constraint comprises:
wherein the content of the first and second substances,
an observation matrix representing the initial position estimate and the positions of simulated satellites whose positions are determined from the satellite parameters, and e represents pseudorange residuals.
4. The positioning system of claim 1, wherein the processor determines simulated satellite pseudorange estimates between the terminal and the simulated satellites based on the initial position estimate and satellite parameters of the simulated satellites; the processor also determines a pseudolite pseudorange estimate between the terminal and the pseudolite based on the simulated satellite pseudo range estimate and the reference time delay.
5. The positioning system of claim 1, wherein the satellite parameters comprise ephemeris information and pseudorandom codes of GNSS satellites.
6. The positioning system of claim 1, wherein the reference time delay is determined based on signal coverage of pseudolites, pseudolites positions, and satellite parameters of pseudolites.
7. The positioning system of claim 1, wherein the positioning system further comprises a data center providing satellite parameters and a reference time delay; the terminal further comprises a communication module, and the communication module receives the satellite parameters and the reference time delay provided by the data center.
8. The positioning system according to claim 1, wherein the processor estimates a non-linear error in calculating the accurate position estimation of the terminal, and determines that the calculation result is correct when the non-linear error is less than a predetermined threshold; and when the nonlinear error is larger than the threshold value, performing re-calculation.
9. A positioning system according to claim 1, wherein the receiver of the terminal further receives satellite signals from one or more satellites, the receiver determining an initial position estimate for the terminal from the received simulated satellite signals in combination with the received satellite signals from the satellites.
10. A pseudolite based positioning method comprising:
simulating satellite signals of the satellites and sending the simulated satellite signals through each pseudolite in the pseudolites according to the satellite parameters, the pseudolite positions and the reference time delay;
receiving the simulated satellite signals, and determining initial position estimation of the user terminal according to the received simulated satellite signals; and
obtaining a pseudolite pseudorange estimate between the user terminal and a pseudolite based on the initial position estimate and the reference time delay to determine an accurate position estimate for the user terminal,
obtaining pseudo-range residual constraints of the simulated satellites according to the determined initial position estimation; and constructing a pseudo-satellite pseudo-range equation according to the pseudo-satellite pseudo-range estimation value and the pseudo-satellite position, and determining the accurate position estimation of the user terminal by combining the pseudo-satellite pseudo-range equation and the simulated satellite pseudo-range residual constraint.
11. The positioning method according to claim 10, wherein said simulated satellite pseudorange residuals constraint is that pseudorange residuals satisfy a norm minimum constraint.
12. The positioning method of claim 11, wherein the simulated satellite pseudorange residuals satisfying a norm minimum constraint comprises:
wherein the content of the first and second substances,
an observation matrix representing the initial position estimate and the positions of simulated satellites whose positions are determined from the satellite parameters, and e represents pseudorange residuals.
13. The positioning method according to claim 10, wherein a simulated satellite pseudorange estimate between the user terminal and the simulated satellite is determined based on the initial position estimate and satellite parameters of the simulated satellite; and determining a pseudo-satellite pseudo-range estimated value between the user terminal and the pseudo-satellite according to the simulated satellite pseudo-range estimated value and the reference time delay.
14. The positioning method according to claim 10, wherein the satellite parameters comprise ephemeris information and pseudo random codes of GNSS satellites.
15. The positioning method according to claim 10, wherein the reference time delay is determined based on signal coverage of the pseudolite, pseudolite position, satellite parameters of the pseudolite.
16. The positioning method of claim 10, comprising: estimating a nonlinear error in the process of calculating the accurate position estimation of the terminal, and determining that a calculation result is correct when the nonlinear error is smaller than a preset threshold value; and when the nonlinear error is larger than the threshold value, performing re-calculation.
17. The positioning method of claim 10, comprising: satellite signals from one or more satellites are received, and an initial position estimate for the terminal is determined from the received simulated satellite signals in combination with the satellite signals from the satellites.
18. A pseudolite based positioning system comprising:
the receiving device receives satellite signals from a plurality of satellites, and obtains satellite parameters of each satellite and transmission time delay of the satellite signals from each satellite to the receiving device;
each pseudolite regenerates the satellite signal of one satellite of the pseudolites according to the satellite parameter of the satellite and the transmission delay of the satellite signal from the satellite to a receiving device, and forwards the regenerated satellite signal; and
a terminal, comprising:
a receiver for determining an initial position estimate of the terminal based on the received forwarded satellite signals; and
a processor for obtaining pseudolite pseudorange estimates between a terminal and pseudolites based on the initial position estimate, satellite parameters of the satellites, pseudolite positions, and propagation delays of satellite signals from the satellites to a receiving device to determine an accurate position estimate for the terminal,
the processor obtains a forwarded satellite pseudo-range residual constraint according to the initial position estimation determined by the receiver, constructs a pseudo-satellite pseudo-range equation according to the pseudo-satellite pseudo-range estimation value and the pseudo-satellite position, and determines the accurate position estimation of the terminal by combining the pseudo-satellite pseudo-range equation and the forwarded satellite pseudo-range residual constraint.
19. The positioning system of claim 18, wherein the transsatellite pseudorange residual constraints include a constraint that a pseudorange residual satisfies a norm minimum.
20. The positioning system of claim 19, wherein the forwarded satellite pseudorange residuals satisfying a norm minimum constraint comprises:
wherein the content of the first and second substances,
indicating the position of the initial position estimate and the transponded satelliteRepresents a pseudorange residual, wherein the position of the transponded satellite is determined from satellite parameters of the satellite.
21. The positioning system of claim 18, wherein the processor determines a transsatellite pseudorange estimate between the terminal and the transsatellite based on the initial position estimate and satellite parameters of the transsatellite; the processor also determines a pseudolite pseudorange estimate between the terminal and the pseudolite based on the forward satellite pseudo range estimate and the transfer delay.
22. The positioning system of claim 18, wherein the satellite parameters of the transponded satellites include ephemeris information and pseudorandom codes of GNSS satellites.
23. The positioning system of claim 18, wherein the receiving device further comprises a data center providing satellite parameters of each satellite obtained by the receiving device and a propagation delay of a satellite signal from each satellite to the receiving device; the terminal also comprises a communication module which receives the satellite parameters and the transmission time delay provided by the data center.
24. The positioning system according to claim 18, wherein the processor estimates a non-linear error in calculating the accurate position estimation of the terminal, and determines that the calculation result is correct when the non-linear error is less than a predetermined threshold; and when the nonlinear error is larger than the threshold value, performing re-calculation.
25. A positioning system according to claim 18, wherein the receiver of the terminal further receives satellite signals from one or more satellites, the receiver determining an initial position estimate for the terminal from the retransmitted satellite signals in combination with the satellite signals from the satellites.
26. A pseudolite based positioning method comprising:
receiving satellite signals from a plurality of satellites, and obtaining satellite parameters of each satellite and transmission time delay from the transmission to the reception of each satellite;
regenerating the satellite signal of one of the plurality of pseudolites according to the satellite parameter of the satellite and the transmission delay from the satellite to the satellite signal, and forwarding the regenerated satellite signal;
receiving the forwarded satellite signals, and determining initial position estimation of the user terminal according to the received forwarded satellite signals; and
obtaining a pseudolite pseudorange estimate between the terminal and a pseudolite based on the initial position estimate, satellite parameters of the satellite, the pseudolite position, and a propagation delay of the satellite signal from the satellite to determine an accurate position estimate for the user terminal,
obtaining a forward satellite pseudo-range residual constraint according to the determined initial position estimation, constructing a pseudo-satellite pseudo-range equation according to the pseudo-satellite pseudo-range estimation value and the pseudo-satellite position, and determining the accurate position estimation of the user terminal by combining the pseudo-satellite pseudo-range equation and the forward satellite pseudo-range residual constraint.
27. The positioning method of claim 26, wherein the forward satellite pseudorange residual constraints include a pseudorange residual satisfying a norm minimum constraint.
28. The positioning method of claim 27, wherein the transponded satellite pseudorange residuals satisfying a norm minimum constraint comprises:
wherein the content of the first and second substances,
representing initial position estimation and forwardingAn observation matrix between the positions of the satellites, e, represents the pseudorange residuals, wherein the positions of the transponded satellites are determined from the satellite parameters of the satellites.
29. The positioning method according to claim 26, wherein a transponded satellite pseudorange estimate between the user terminal and the transponded satellite is determined from the initial position estimate and satellite parameters of the transponded satellite; and determining a pseudo-satellite pseudo-range estimated value between the terminal and the pseudo-satellite according to the forward satellite pseudo-range estimated value and the transmission time delay.
30. The positioning method according to claim 26, wherein the satellite parameters of the transponded satellites include ephemeris information and pseudorandom codes of GNSS satellites.
31. The positioning method of claim 26, comprising: estimating a nonlinear error in the process of calculating the accurate position estimation of the terminal, and determining that a calculation result is correct when the nonlinear error is smaller than a preset threshold value; and when the nonlinear error is larger than the threshold value, performing re-calculation.
32. The positioning method according to claim 26, wherein satellite signals from one or more satellites are received, and an initial position estimate for the terminal is determined from the retransmitted satellite signals in combination with the satellite signals from the satellites.
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| CN110716218A (en) * | 2019-10-29 | 2020-01-21 | 中国电子科技集团公司第五十四研究所 | Array pseudolite and GNSS combined positioning method and system |
| CN110716217A (en) * | 2019-10-29 | 2020-01-21 | 中国电子科技集团公司第五十四研究所 | Array pseudo satellite indoor positioning method and system |
| CN112558131A (en) * | 2020-11-24 | 2021-03-26 | 北京百度网讯科技有限公司 | AR navigation method and apparatus, electronic device, navigation system, and storage medium |
| CN113093251B (en) * | 2021-03-18 | 2022-05-27 | 中国电子科技集团公司第五十四研究所 | High-precision indoor positioning method based on carrier phase of pseudolite |
| CN112698361B (en) * | 2021-03-24 | 2021-07-13 | 航天宏图信息技术股份有限公司 | Positioning method and device based on pseudo satellite |
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