CN116263334A - Positioning method, positioning device, computer apparatus, storage medium, and program product - Google Patents
Positioning method, positioning device, computer apparatus, storage medium, and program product Download PDFInfo
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Abstract
The present application relates to a positioning method, apparatus, computer device, storage medium and program product. The method can be applied to map navigation, map construction, automatic driving or intelligent travel scenes, and comprises the following steps: determining a target position from candidate positions corresponding to the region where the target equipment of the current epoch is located according to the satellite visibility degree, calculating double-difference pseudo-range and double-difference frequency shift of the current epoch based on the target visible satellite observed by the current epoch together with the reference base station at the target position, adding an end variable node to a factor graph optimized by the previous epoch according to the double-difference pseudo-range and the double-difference frequency shift of the current epoch to obtain a factor graph corresponding to the current epoch, adjusting the factor graph corresponding to the current epoch with the posterior probability maximization of the factor graph corresponding to the current epoch as a target to obtain the factor graph optimized by the current epoch, and generating positioning information of the current epoch of the target equipment based on the end variable node in the factor graph optimized by the current epoch. The method can improve the positioning accuracy.
Description
Technical Field
The present application relates to the field of computer technology, and in particular, to a positioning method, an apparatus, a computer device, a storage medium, and a computer program product.
Background
Along with the rapid development of intelligent equipment and computer technology, the location service is more and more widely applied to intelligent equipment such as intelligent mobile phones, vehicle-mounted navigator and the like, and great convenience is brought to daily life of people. The global satellite navigation system can be mounted in intelligent devices such as smart phones and vehicle-mounted navigator, and based on position services derived from the global satellite navigation system, such as position sharing services provided by social applications, route navigation services provided by navigation applications and the like, daily lives of people are enriched and enriched.
At present, the global satellite navigation system utilizes satellite signals received by the intelligent equipment to realize positioning of the intelligent equipment. However, in practical applications, the user may be in a satellite signal shielding area with complex roads, such as multiple buildings and viaducts, and satellite signals received by the intelligent device may be blocked, so that accuracy of positioning information generated by using the global satellite navigation system is low.
Disclosure of Invention
In view of the foregoing, it is desirable to provide a positioning method, apparatus, computer device, computer-readable storage medium, and computer program product that can improve positioning accuracy.
In a first aspect, the present application provides a positioning method. The method comprises the following steps:
determining candidate positions corresponding to the areas where the current epoch target devices are located;
determining satellite visibility corresponding to the candidate position based on a target shielding object on an azimuth angle between the current epoch candidate position and a satellite observed by target equipment, and determining a target position from the candidate position according to the satellite visibility;
determining a target visible satellite observed by the current epoch together with a reference base station at a target position;
calculating double-difference pseudo-ranges of the current epoch according to the observed pseudo-ranges between the current epoch target position and the target visible satellite and the reference pseudo-ranges between the reference base station and the target visible satellite, and calculating double-difference frequency shifts of the current epoch according to the observed frequency shifts between the current epoch target position and the target visible satellite and the reference frequency shifts between the reference base station and the target visible satellite;
adding an end variable node to the factor graph optimized by the previous epoch according to the double-difference pseudo range of the current epoch and the double-difference frequency shift of the current epoch to obtain a factor graph corresponding to the current epoch, adjusting the factor graph corresponding to the current epoch with the posterior probability maximization of the factor graph corresponding to the current epoch as a target to obtain the factor graph optimized by the current epoch, and generating the positioning information of the current epoch of the target equipment based on the end variable node in the factor graph optimized by the current epoch.
In a second aspect, the present application also provides a positioning device. The device comprises:
the candidate position determining module is used for determining candidate positions corresponding to the area where the current epoch target device is located;
the target position determining module is used for determining satellite visibility corresponding to the candidate position based on a target shielding object in azimuth angle between the candidate position of the current epoch and a satellite observed by the target equipment, and determining a target position from the candidate position according to the satellite visibility;
the visible satellite determining module is used for determining a target visible satellite observed by the current epoch together with the reference base station at the target position;
the calculation module is used for calculating double-difference pseudo ranges of the current epoch according to the observed pseudo ranges between the target position and the target visible satellite of the current epoch and the reference pseudo ranges between the reference base station and the target visible satellite, and calculating double-difference frequency shifts of the current epoch according to the observed frequency shifts between the target position and the target visible satellite of the current epoch and the reference frequency shifts between the reference base station and the target visible satellite;
the positioning module is used for adding an end variable node to the factor graph optimized by the previous epoch according to the double-difference pseudo range of the current epoch and the double-difference frequency shift of the current epoch to obtain a factor graph corresponding to the current epoch, adjusting the factor graph corresponding to the current epoch with the posterior probability maximization of the factor graph corresponding to the current epoch as a target to obtain the factor graph optimized by the current epoch, and generating positioning information of the current epoch of the target equipment based on the end variable node in the factor graph optimized by the current epoch.
In one embodiment, the candidate position determination module is further configured to: determining an initial estimated position of the target device; constructing a candidate region by taking the initial estimated position as a center; the candidate region is equally divided into a plurality of candidate positions.
In one embodiment, the target location determination module is further configured to: acquiring a satellite set observed by the target equipment in the current epoch; for each candidate position, determining an azimuth angle of the candidate position and a target shielding object positioned on the azimuth angle, and calculating an altitude angle between the candidate position and the target shielding object as an altitude angle threshold; calculating an altitude angle between the candidate position and each satellite in the satellite set; taking the satellites with the altitude angles larger than the altitude angle threshold value in the satellite set as visible satellites observed by the current epoch at the candidate positions; and determining satellite visibility corresponding to the candidate position according to the number of the visible satellites.
In one embodiment, the target location determination module is further configured to: determining the signal-to-noise ratio corresponding to the visible satellite observed by the current epoch at the candidate position; determining the number of satellites in the visible satellites, wherein the signal-to-noise ratio of the satellites is greater than a preset threshold; determining satellite visibility degrees corresponding to the candidate positions according to a first number of satellites in the visible satellites, wherein the signal-to-noise ratio of the satellites is larger than a preset threshold value, and the satellite visibility degrees are positively correlated with the first number; or determining the satellite visibility corresponding to the candidate position according to a second number of satellites with signal-to-noise ratios smaller than or equal to the preset threshold value in satellites except the visible satellites in the satellite set, wherein the satellite visibility is inversely related to the second number.
In one embodiment, the target location determination module is further configured to: acquiring a satellite set observed by a current epoch reference base station; determining an azimuth angle of the reference base station and a target shielding object positioned on the azimuth angle of the reference base station, and calculating a height angle between the reference base station and the target shielding object as a height angle threshold; calculating an altitude angle between the reference base station and each satellite in the satellite set; taking the satellites with the altitude angle larger than the altitude angle threshold value in the satellite set as visible satellites observed by the reference base station in the current epoch; the visible satellite determining module is further configured to: and determining the target visible satellite observed by the current epoch together with the reference base station at the target position according to the intersection set of the visible satellite observed by the current epoch at the target position and the visible satellite observed by the reference base station.
In one embodiment, the computing module is further configured to: acquiring real-time satellite state information corresponding to the target visible satellite observed by the target equipment in the current epoch; determining an observed pseudo range between the target position and each target visible satellite according to the real-time satellite state information; acquiring reference satellite state information corresponding to the target visible satellite observed by the reference base station in the current epoch; and calculating a reference pseudo range between the reference base station and each target visible satellite according to the reference satellite state information.
In one embodiment, the computing module is further configured to:
wherein ,
a double-difference pseudo range representing the current epoch target device a and the reference base station b; />
An observed pseudo-range representing the current epoch target device a at the target position to the target visible satellite j,/>
Representing a reference pseudo range of the current epoch reference base station b to the target visible satellite j; />
Representing the observed pseudoranges of the current epoch target device a to the target satellites in view k at the target location,
representing a reference pseudo range of the current epoch reference base station b to the target visible satellite j; />
Representing the double-difference geometric distance between the current epoch target device a and the reference base station b; />
Representing the double difference error of the current epoch target device a and the reference base station b, which is the correlation error of the pseudorange and carrier phase observations.
In one embodiment, the computing module is further configured to: acquiring a first carrier phase observation value corresponding to the target visible satellite observed by the target equipment in a current epoch and a second carrier phase observation value, which is determined in a previous epoch, observed by the target equipment on the target visible satellite, and calculating an observation frequency shift corresponding to the current epoch; and acquiring a first carrier phase reference value observed by the reference base station for the target visible satellite in the current epoch and a second carrier phase reference value observed by the reference base station for the target visible satellite in the previous epoch, and calculating the reference frequency shift corresponding to the current epoch.
In one embodiment, the computing module is further configured to:
wherein ,
representing a double difference frequency shift of the current epoch target device a and the reference base station b; />
Indicating the observed frequency shift of the current epoch target device a to the target visible satellite j at the target position,/>
Representing the reference frequency shift of the current epoch reference base station b to the target visible satellite j; />
Representing the observed frequency shift of the current epoch target device a to the target satellite k at the target location,
representing the reference frequency shift of the current epoch reference base station b to the target visible satellite j.
wherein ,
cosine and +.f representing the direction of the connection of the target device a to the target visible satellite j at the target position>
The cosine of the connection line direction of the target equipment a at the target position and the target visible satellite k is represented; v a Representing the speed of the target device a; />
Cosine representing the direction of connection of reference base station b to target visible satellite j, < >>
Indicating reference base station b and destinationMarking the cosine of the k connection line direction of the visible satellite; v j Representing the velocity, v, of the target visible satellite j k Representing the velocity of the target visible satellite k; />
Representing the double difference error of the target device a and the reference base station b in the current epoch, which is the correlation error of the pseudorange and the carrier phase observations.
In one embodiment, the positioning module is further configured to: taking the double difference pseudo range of the current epoch and the double difference frequency shift of the current epoch as factor nodes, calculating the position of the target equipment in the current epoch according to the double difference pseudo range of the current epoch, calculating the speed of the target equipment in the current epoch according to the double difference frequency shift of the current epoch, and adding an end variable node to a factor graph optimized for the previous epoch according to the position of the current epoch and the speed of the current epoch to obtain a factor graph corresponding to the current epoch; and adjusting the value of each variable node in the factor graph corresponding to the current epoch with the aim of maximizing posterior probability calculated based on the factor node and the variable node in the factor graph corresponding to the current epoch, obtaining the factor graph optimized by the current epoch, and generating the positioning information of the current epoch of the target equipment based on the position represented by the last variable node in the factor graph optimized by the current epoch.
In one embodiment, the positioning module is further configured to: calculating a first conditional probability among variable nodes in a factor graph corresponding to the current epoch; calculating a second conditional probability between each variable node and a corresponding factor node in the factor graph corresponding to the current epoch; and calculating the posterior probability of the factor graph corresponding to the current epoch according to the first conditional probability and the second conditional probability.
In a third aspect, the present application also provides a computer device. The computer device comprises a memory storing a computer program and a processor which when executing the computer program performs the steps of:
determining candidate positions corresponding to the areas where the current epoch target devices are located;
determining satellite visibility corresponding to the candidate position based on a target shielding object on an azimuth angle between the current epoch candidate position and a satellite observed by target equipment, and determining a target position from the candidate position according to the satellite visibility;
determining a target visible satellite observed by the current epoch together with a reference base station at a target position;
calculating double-difference pseudo-ranges of the current epoch according to the observed pseudo-ranges between the current epoch target position and the target visible satellite and the reference pseudo-ranges between the reference base station and the target visible satellite, and calculating double-difference frequency shifts of the current epoch according to the observed frequency shifts between the current epoch target position and the target visible satellite and the reference frequency shifts between the reference base station and the target visible satellite;
Adding an end variable node to the factor graph optimized by the previous epoch according to the double-difference pseudo range of the current epoch and the double-difference frequency shift of the current epoch to obtain a factor graph corresponding to the current epoch, adjusting the factor graph corresponding to the current epoch with the posterior probability maximization of the factor graph corresponding to the current epoch as a target to obtain the factor graph optimized by the current epoch, and generating the positioning information of the current epoch of the target equipment based on the end variable node in the factor graph optimized by the current epoch.
In a fourth aspect, the present application also provides a computer-readable storage medium. The computer readable storage medium having stored thereon a computer program which when executed by a processor performs the steps of:
determining candidate positions corresponding to the areas where the current epoch target devices are located;
determining satellite visibility corresponding to the candidate position based on a target shielding object on an azimuth angle between the current epoch candidate position and a satellite observed by target equipment, and determining a target position from the candidate position according to the satellite visibility;
determining a target visible satellite observed by the current epoch together with a reference base station at a target position;
Calculating double-difference pseudo-ranges of the current epoch according to the observed pseudo-ranges between the current epoch target position and the target visible satellite and the reference pseudo-ranges between the reference base station and the target visible satellite, and calculating double-difference frequency shifts of the current epoch according to the observed frequency shifts between the current epoch target position and the target visible satellite and the reference frequency shifts between the reference base station and the target visible satellite;
adding an end variable node to the factor graph optimized by the previous epoch according to the double-difference pseudo range of the current epoch and the double-difference frequency shift of the current epoch to obtain a factor graph corresponding to the current epoch, adjusting the factor graph corresponding to the current epoch with the posterior probability maximization of the factor graph corresponding to the current epoch as a target to obtain the factor graph optimized by the current epoch, and generating the positioning information of the current epoch of the target equipment based on the end variable node in the factor graph optimized by the current epoch.
In a fifth aspect, the present application also provides a computer program product. The computer program product comprises a computer program which, when executed by a processor, implements the steps of:
determining candidate positions corresponding to the areas where the current epoch target devices are located;
Determining satellite visibility corresponding to the candidate position based on a target shielding object on an azimuth angle between the current epoch candidate position and a satellite observed by target equipment, and determining a target position from the candidate position according to the satellite visibility;
determining a target visible satellite observed by the current epoch together with a reference base station at a target position;
calculating double-difference pseudo-ranges of the current epoch according to the observed pseudo-ranges between the current epoch target position and the target visible satellite and the reference pseudo-ranges between the reference base station and the target visible satellite, and calculating double-difference frequency shifts of the current epoch according to the observed frequency shifts between the current epoch target position and the target visible satellite and the reference frequency shifts between the reference base station and the target visible satellite;
adding an end variable node to the factor graph optimized by the previous epoch according to the double-difference pseudo range of the current epoch and the double-difference frequency shift of the current epoch to obtain a factor graph corresponding to the current epoch, adjusting the factor graph corresponding to the current epoch with the posterior probability maximization of the factor graph corresponding to the current epoch as a target to obtain the factor graph optimized by the current epoch, and generating the positioning information of the current epoch of the target equipment based on the end variable node in the factor graph optimized by the current epoch.
According to the positioning method, the device, the computer equipment, the storage medium and the computer program product, on one hand, the satellite visible degree corresponding to the candidate position is determined based on the candidate position corresponding to the area where the current epoch target equipment is located and the target shielding object on the azimuth angle between satellites observed by the target equipment, the target position is determined from the candidate position according to the satellite visible degree, and the target visible satellite observed by the current epoch at the target position and the reference base station participates in the subsequent positioning process; on the other hand, adding an end variable node to the factor graph optimized by the previous epoch according to the double-difference pseudo range of the current epoch and the double-difference frequency shift of the current epoch to obtain a factor graph corresponding to the current epoch, adjusting the factor graph corresponding to the current epoch with the posterior probability maximization of the factor graph corresponding to the current epoch as a target to obtain the factor graph optimized by the current epoch, generating positioning information of the current epoch of the target equipment based on the end variable node in the factor graph optimized by the current epoch, optimizing the position information of the target equipment based on satellite observation data solution through a factor graph algorithm, and improving the positioning accuracy.
Drawings
FIG. 1 is a diagram of an application environment for a positioning method in one embodiment;
FIG. 2 is a block diagram of a global satellite navigation system chip in one embodiment;
FIG. 3 is a flow chart of a positioning method in one embodiment;
FIG. 4 is a schematic diagram of determining candidate locations in one embodiment;
FIG. 5 is a schematic diagram of a target occluding object in azimuth determining candidate locations in one embodiment;
FIG. 6 is a schematic diagram of a visible satellite and a non-visible satellite in one embodiment;
FIG. 7 is a diagram of a factor graph corresponding to a current epoch in one embodiment;
FIG. 8 is a schematic diagram of determining a visible satellite corresponding to a candidate position in one embodiment;
FIG. 9 is a schematic flow chart of determining a visible satellite corresponding to a candidate position in one embodiment;
FIG. 10 is a schematic diagram of computing double-difference pseudoranges for a current epoch in one embodiment;
FIG. 11 is a diagram of a double difference frequency shift calculation for a current epoch in one embodiment;
FIG. 12 is a diagram of a factor graph corresponding to a current epoch in one embodiment;
FIG. 13 is a flow diagram of a positioning method in one embodiment;
FIG. 14 is a block diagram of a positioning device in one embodiment;
fig. 15 is an internal structural view of a computer device in one embodiment.
Detailed Description
In order to make the objects, technical solutions and advantages of the present application more apparent, the present application will be further described in detail with reference to the accompanying drawings and examples. It should be understood that the specific embodiments described herein are for purposes of illustration only and are not intended to limit the present application.
The positioning method provided by the embodiment of the application can be applied to an application environment shown in fig. 1. Wherein the terminal 102 receives satellite signals transmitted by satellites 106. The terminal 102 may also communicate with the server 104 via a network. The data storage system may store data that the server 104 needs to process. The data storage system may be integrated on the server 104 or may be located on a cloud or other network server.
The terminal 102 may be, but not limited to, various personal computers, notebook computers, smart phones, tablet computers, internet of things devices and portable wearable devices, where the internet of things devices may be devices with positioning functions, such as smart speakers, smart televisions, smart air conditioners, smart vehicle devices, and the like. The portable wearable device may be a smart watch, smart bracelet, headset, or the like. The server 104 may be an independent physical server, a server cluster or a distributed system formed by a plurality of physical servers, or a cloud server providing basic cloud computing services such as cloud storage, network services, cloud communication, big data, an artificial intelligent platform, and the like. The terminal and the server may be directly or indirectly connected through wired or wireless communication, which is not limited herein. The satellite 106 may be a satellite of one or more satellite navigation systems, which is not limited herein.
In one embodiment, an application (hereinafter referred to as a location application) that provides a location service is run on the terminal 102, and the server 104 is a server corresponding to the location application. Both the terminal 102 and the server 104 may be used as execution bodies to execute the positioning method provided in the embodiments of the present application.
In one embodiment, taking the terminal 102 to execute the positioning method provided in the embodiment of the present application as an example, first, the terminal 102 receives a satellite signal sent by the satellite 106, and determines a candidate position corresponding to an area where the current epoch terminal 102 is located based on the received satellite signal; then, terminal 202 determines a satellite visibility level corresponding to the candidate position based on the current epoch candidate position and the target occlusion object in azimuth between satellites observed by the target device, and determines a target position from the candidate positions according to the satellite visibility level; next, the terminal 102 determines a target visible satellite observed by the current epoch together with the reference base station at the target position; then, the terminal 102 calculates a double-difference pseudo range of the current epoch according to the observed pseudo range between the target position of the current epoch and the target visible satellite and the reference pseudo range between the reference base station and the target visible satellite, and calculates a double-difference frequency shift of the current epoch according to the observed frequency shift between the target position of the current epoch and the target visible satellite and the reference frequency shift between the reference base station and the target visible satellite; then, the terminal 102 adds an end variable node to the factor graph optimized by the previous epoch according to the double-difference pseudo range of the current epoch and the double-difference frequency shift of the current epoch to obtain a factor graph corresponding to the current epoch, adjusts the factor graph corresponding to the current epoch with the posterior probability maximization of the factor graph corresponding to the current epoch as a target to obtain the factor graph optimized by the current epoch, and generates positioning information of the current epoch of the terminal 102 based on the end variable node in the factor graph optimized by the current epoch.
The positioning method provided by the embodiment of the application is realized based on a global satellite navigation system (Global Navigation Satellite System), and the global satellite navigation system is a unified name of satellite navigation positioning systems such as Beidou systems (BeiDou Navigation Satellite System), GPS (Global Positioning System), GLONASS (Global Navigation Satellite System), galileo (Galileo satellite navigation system) and the like. The global satellite navigation system is composed of a satellite constellation, a ground monitoring station and satellite receiving equipment. The satellite receiving device is carried with a global satellite navigation system chip, which is directly oriented to users and is one of important links of navigation and positioning. Along with the development of corresponding hardware of the global satellite navigation system, the chip of the global satellite navigation system can observe satellite signals of a plurality of satellite navigation systems, and each satellite navigation system has certain differences in signal system, space-time reference and other aspects, but also has the mutual compatibility capability, and the development of a plurality of systems provides more satellite data for navigation positioning, so that the precision, reliability and completeness of navigation positioning are improved.
Referring to fig. 2, fig. 2 is a block diagram of a global satellite navigation system chip in one embodiment. It can be seen that the global satellite navigation system chip comprises a radio frequency front end processing module, a baseband signal processing module and a position speed time resolving module. Firstly, an antenna transmits a received satellite signal to a radio frequency front end processing module through a feeder line; then, the radio frequency front-end processing module amplifies the original weak signal through a pre-filter and a pre-amplifier, performs down-conversion mixing operation on the amplified signal and a sine wave local oscillation signal generated by the radio frequency front-end processing module to enable the amplified signal to become an intermediate frequency signal, and converts the intermediate frequency signal into a digital intermediate frequency signal through an analog-to-digital converter and transmits the digital intermediate frequency signal to the baseband signal processing module; then, the baseband signal processing module copies a pseudo range and a carrier signal consistent with the intermediate frequency signal, and acquires and tracks the pseudo range and the carrier signal to obtain information such as a pseudo range, a carrier phase observation value, a navigation message and the like; and finally, the position, speed and time resolving module resolves the information such as position, speed and time based on the information processed by the baseband signal processing module. The specific processing scheme adopted in the calculation of the position, speed and time calculation module is determined by the global satellite navigation system chip, so that a user does not have permission to modify the global satellite navigation system chip, the global satellite navigation system chip is a black box in the equipment, and only limited information such as position, speed and time can be output.
The smart device may obtain satellite related raw observations through an application program interface, including the receiver's quartz Clock information (GNSS Clock), the observations of each satellite signal (GNSS Measurement), satellite ephemeris information (GNSS Navigation Message), etc. For example, an intelligent device based on an Android operating system can obtain original observation data related to a satellite by using android.locationapi, and errors caused by satellite orbit and atmospheric delay are eliminated by correcting the original observation data, so that positioning accuracy is improved.
In one embodiment, as shown in fig. 3, a positioning method is provided, which is illustrated by taking an example that the method is applied to the terminal 102 (hereinafter referred to as a target device) in fig. 1, and includes the following steps:
step 302, determining a candidate position corresponding to the area where the current epoch target device is located.
The target device is a device for generating positioning information, such as a smart phone, a tablet computer, a portable wearable device, an intelligent vehicle-mounted device, an outdoor navigation device and the like. The epoch is a time point of satellite related data collection, and the satellite related data collected by the previous epoch and the satellite related data collected by the current epoch are compared with each other. The satellite related data collected by different epochs can be used to obtain other data of the corresponding epochs according to the positioning method provided by the application, such as candidate positions, visible satellites, factor graphs, positioning information and the like. The epoch may be used to describe a batch of satellite signal acquisitions by the target device, e.g., the target device acquires satellite signals once every predetermined time period, and once for each increase in acquisition times, the epoch is incremented. The current epoch is the current acquisition batch of the target equipment. It should be noted that, as used herein, the "previous epoch" is used to describe the last satellite related data acquisition time point, the "current epoch" is used to describe the current satellite related data acquisition time point, and the "previous epoch" and the "current epoch" are relatively changed, for example, after the "previous epoch" ends, the "current epoch" needs to be taken as a new "previous epoch".
In one embodiment, the target device acquires a satellite signal received in a current epoch, determines an initial estimated position of the target device in the current epoch according to the satellite signal, and determines a candidate position corresponding to an area where the target device in the current epoch is located according to the initial estimated position.
In one embodiment, the target device determines real-time satellite state information for the current epoch based on satellite signals received at the current epoch, and determines an initial estimated position of the target device at the current epoch based on the real-time satellite state information.
The real-time satellite state information is satellite related information observed by the target device in the current epoch, such as satellite position, satellite number, satellite altitude angle, satellite azimuth angle, satellite signal strength, pseudo-range observation value, carrier phase observation value and the like. The target device can be carried with a global satellite navigation chip, receives satellite signals through the global satellite navigation chip, reads original observation data corresponding to the satellite signals in the global satellite navigation chip, and determines real-time satellite state information based on the original observation data.
In one embodiment, the target device may determine an initial estimated location of the target device at the current epoch based on real-time satellite state information of the current epoch according to a general positioning strategy. Common positioning strategies such as single point positioning (Single point positioning, SPP), real-time dynamic measurement (Real Time Kinematic, RTK), etc.
In one embodiment, the target device constructs a candidate region according to the initial estimated position of the current epoch, and determines a candidate position corresponding to the region where the target device of the current epoch is located according to the candidate region.
In one embodiment, the target device constructs a candidate region according to the initial estimated position of the current epoch and the predetermined range, and determines a candidate position corresponding to the region where the target device of the current epoch is located in the candidate region. The size of the predetermined range may be set according to an actual application scenario.
In one embodiment, the target device builds a candidate region centered on the initial estimated location of the current epoch, in conjunction with a predetermined range, and equally divides the candidate region into a plurality of candidate locations.
For example, referring to FIG. 4, FIG. 4 illustrates a schematic diagram of determining candidate locations in one embodiment. It can be seen that the target device constructs the candidate region 404 with the initial estimated position 402 of the current epoch as the center, equally divides the candidate region 404 into a plurality of grids, and uses the center position of each grid as one candidate position, where the initial estimated position 402 is also one of the candidate positions of the candidate region 404. The side length of the grid can be set according to the actual application scene.
Step 304, determining satellite visibility corresponding to the candidate position based on the target shielding object in azimuth angle between the current epoch candidate position and the satellite observed by the target device, and determining the target position from the candidate positions according to the satellite visibility.
The azimuth angle of any position point on the ground is the angle between the projection of the connecting line of the satellite and the position point on the ground and the north direction of the ground. The target blocking object is an object, such as a building, an overhead bridge, a utility pole, a tree, etc., for which there is a possibility of blocking propagation of the target satellite signal.
For example, referring to FIG. 5, FIG. 5 illustrates a schematic diagram of a target occluding object in one embodiment in determining an azimuth between a candidate position and a satellite observed by a target device. It can be seen that an azimuth 506 is formed between the candidate position 502 and the satellite 504, and that a target occluding object 508 is present at the azimuth 506.
The satellite visibility is used for representing the number of visible satellites corresponding to the candidate positions, the visible satellites represent satellites which can be directly observed in a non-shielding state, and the greater the number of the visible satellites corresponding to the candidate positions, the greater the satellite visibility.
For example, referring to fig. 6, fig. 6 shows a schematic diagram of a visible satellite and a non-visible satellite in one embodiment. It can be seen that, assuming that the target device receives satellite signals of the satellite 604 and the satellite 606 at the candidate position 602, the satellite signal of the satellite 604 received by the target device is a satellite signal directly received in the unobstructed state, and the satellite signal of the satellite 606 received by the target device is a satellite signal received after being reflected by the building 608, the satellite 604 is a visible satellite corresponding to the candidate position 602, and the satellite 606 is an invisible satellite corresponding to the candidate position 602.
In one embodiment, the target device determines a plurality of candidate locations corresponding to an area where the target device of the current epoch is located, determines a satellite visibility level corresponding to each candidate location based on a target shielding object in azimuth between each candidate location of the current epoch and a satellite observed by the target device, and determines a target location from each candidate location according to the determined satellite visibility level.
In one embodiment, the target device determines the satellite positions of each of the observation satellites of the current epoch based on the satellite signals received at the current epoch, the observation satellites being satellites at which the target device received satellite signals at the current epoch. For each candidate location, the target device may calculate an azimuth angle between the current epoch candidate location and the respective observed satellite based on the current epoch candidate location and the satellite locations of the respective observed satellites.
In one embodiment, for each candidate location, the target device determines a target occluding object between the candidate location and the respective observing satellite at the azimuth of the candidate location and the respective observing satellite, respectively. Optionally, the target device searches for an occlusion object between the candidate position and each observation satellite within a predetermined range corresponding to the candidate position, and uses the highest occlusion object between the candidate position and each observation satellite as a target occlusion object between the current epoch candidate position and each observation satellite.
In one embodiment, the target device may determine the visible satellites observed by the current epoch candidate position based on the target occluding objects between the current epoch candidate position and each of the observed satellites, and determine the satellite visibility corresponding to the candidate position based on the number of visible satellites.
In one embodiment, the target device may score each candidate location according to the number of visible satellites corresponding to each candidate location, for example, score each visible satellite corresponding to the candidate location, and use the score corresponding to each candidate location as the satellite visibility corresponding to each candidate location.
In one embodiment, the target device may determine the invisible satellites corresponding to the current epoch candidate position based on the target occluding objects between the current epoch candidate position and each of the observed satellites, and determine the satellite visibility level corresponding to the candidate position based on the number of invisible satellites.
In one embodiment, the target device may score each candidate location according to the number of invisible satellites corresponding to each candidate location, for example, score each invisible satellite corresponding to the candidate location by one score, and use the score corresponding to each candidate location as the satellite visibility corresponding to each candidate location.
In one embodiment, the target device determines satellite visibility levels corresponding to the candidate locations, ranks the candidate locations according to the determined satellite visibility levels, for example, ranks from high to low or ranks from low to high, and takes the candidate location with the greatest satellite visibility level as the target location.
The reference base station may be a general satellite tracking reference station (Reference Stations), which is a data source of the CORS (Continuously Operating Reference Stations, continuously operating reference station), for long-term continuous acquisition, tracking, recording and transmission of satellite signals. The reference base station can also be intelligent equipment with a positioning function, such as intelligent mobile phones, tablet computers, portable wearable equipment, intelligent vehicle-mounted equipment, outdoor navigation equipment and the like.
In one embodiment, the target device searches for a reference base station closest to the target location as a reference base station corresponding to the area in which the target device is currently located.
In one embodiment, the target device determines a reference base station corresponding to a current area where the target device is located, obtains a visible satellite observed by the reference base station of the current epoch, and obtains a target visible satellite observed by the reference base station and the current epoch at the target position by intersecting the visible satellite observed by the current epoch with the visible satellite observed by the reference base station.
Step 308, calculating the double-difference pseudo-range of the current epoch according to the observed pseudo-range between the target position of the current epoch and the target visible satellite and the reference pseudo-range between the reference base station and the target visible satellite, and calculating the double-difference frequency shift of the current epoch according to the observed frequency shift between the target position of the current epoch and the target visible satellite and the reference frequency shift between the reference base station and the target visible satellite.
In one embodiment, the target device calculates an observed pseudo-range between a current epoch target position and at least two target visible satellites, and a reference pseudo-range between a reference base station and the same target visible satellite, and calculates a double-difference pseudo-range of the current epoch based on the observed pseudo-range and the reference pseudo-range.
In one embodiment, the target device calculates an observed frequency shift between the current epoch target position and at least two target satellites in view and a reference frequency shift between the reference base station and the same target satellites in view, and calculates a double difference frequency shift for the current epoch based on the observed frequency shift and the reference frequency shift.
Step 310, adding an end variable node to the factor graph optimized by the previous epoch according to the double-difference pseudo range of the current epoch and the double-difference frequency shift of the current epoch to obtain a factor graph corresponding to the current epoch, adjusting the factor graph corresponding to the current epoch with the posterior probability maximization of the factor graph corresponding to the current epoch as a target to obtain the factor graph optimized by the current epoch, and generating the positioning information of the current epoch of the target device based on the end variable node in the factor graph optimized by the current epoch.
In the method, a factor graph algorithm is adopted to calculate satellite observation data so as to determine the positioning information of the current epoch of the target equipment. According to the method, the double-difference pseudo range and the double-difference frequency shift are used as factor nodes, the position of the target equipment is calculated according to the double-difference pseudo range, the speed of the target equipment is calculated according to the double-difference frequency shift, and the position and the speed are used as variable nodes.
In one embodiment, the target device uses the double-difference pseudo range of the current epoch and the double-difference frequency shift of the current epoch as factor nodes of the current epoch, calculates the position of the target device in the current epoch according to the double-difference pseudo range of the current epoch, calculates the speed of the target device in the current epoch according to the double-difference frequency shift of the current epoch, and adds tail variable nodes to the factor graph optimized by the previous epoch according to the position of the current epoch and the speed of the current epoch to obtain the factor graph corresponding to the current epoch.
For example, referring to fig. 7, fig. 7 shows a schematic diagram of a factor graph corresponding to a current epoch in one embodiment. It can be seen that the factor graph corresponding to the current epoch includes a variable node X 1 、…、X n-1 、X n, wherein Xn And a variable node newly added for the current epoch. Each variable node has a corresponding factor node, each factor node constructed from a double-difference pseudo-range and a double-difference frequency shift.
In one embodiment, the target terminal adjusts the value of each variable node in the factor graph corresponding to the current epoch, obtains the factor graph optimized by the current epoch when the posterior probability of the factor graph corresponding to the current epoch reaches the maximum, and uses the position represented by the last variable node in the factor graph optimized by the current epoch as the positioning information of the current epoch of the target device.
In the positioning method, on one hand, based on a target shielding object on an azimuth angle between a candidate position corresponding to an area where the current epoch target device is located and a satellite observed by the target device, determining a satellite visible degree corresponding to the candidate position, determining a target position from the candidate position according to the satellite visible degree, and participating in a subsequent positioning process by using the target visible satellite observed by the current epoch together with a reference base station at the target position, wherein the satellite which cannot be directly observed by the target device is eliminated, so that the accuracy of subsequent positioning can be improved; on the other hand, adding an end variable node to the factor graph optimized by the previous epoch according to the double-difference pseudo range of the current epoch and the double-difference frequency shift of the current epoch to obtain a factor graph corresponding to the current epoch, adjusting the factor graph corresponding to the current epoch with the posterior probability maximization of the factor graph corresponding to the current epoch as a target to obtain the factor graph optimized by the current epoch, generating positioning information of the current epoch of the target equipment based on the end variable node in the factor graph optimized by the current epoch, optimizing the position information of the target equipment based on satellite observation data solution through a factor graph algorithm, and improving the positioning accuracy.
In one embodiment, determining the satellite visibility corresponding to the candidate location based on the target occlusion object in azimuth between the current epoch candidate location and the satellite observed by the target device includes: acquiring a satellite set observed by current epoch target equipment; for each candidate position, determining an azimuth angle of the candidate position and a target shielding object positioned on the azimuth angle, and calculating a height angle between the candidate position and the target shielding object as a height angle threshold; calculating the altitude between the candidate position and each satellite in the satellite set; satellites with the altitude angle larger than the altitude angle threshold value in the satellite set are used as visible satellites observed by the current epoch in the candidate positions; and determining satellite visibility corresponding to the candidate positions according to the number of the visible satellites. The altitude angle is the included angle between the connecting line of the satellite and the ground point horizontal plane.
In one embodiment, the target device determines a set of satellites observed by the target device for a current epoch based on satellite signals received at the current epoch, for each candidate location, the target device determines a target occlusion object between the candidate location and each observed satellite in the set of satellites based on azimuth angles between the candidate location for the current epoch and each observed satellite, calculates an altitude between the candidate location and each target occlusion object as an altitude threshold, and the altitude threshold may reflect an altitude at which the target occlusion object may occlude.
In one embodiment, for each candidate location, the target device determines a target occlusion object between the candidate location and each observed satellite in the set of satellites based on azimuth angles between the current epoch candidate location and each observed satellite, determines a boundary location of each target occlusion object from the three-dimensional model of the city, and calculates an altitude angle between the candidate location and each target occlusion object from the candidate location and the boundary location of each target occlusion object. The boundary position of the target shielding object may be the highest point position of the target shielding object, and if there are a plurality of highest points of the target shielding object, the highest point position closest to the candidate position is the highest point position.
In one embodiment, the target device determines satellite positions for each of the observed satellites for the current epoch based on satellite signals received during the current epoch. For each candidate location, the target device may calculate an altitude angle between the current epoch candidate location and the respective observed satellite based on the current epoch candidate location and the satellite locations of the respective observed satellites.
In one embodiment, the target device calculates an altitude between the candidate location of the current epoch and each of the observed satellites, compares the altitude between the candidate location and each of the observed satellites with an altitude threshold determined by the candidate location and each of the target occlusion objects, and uses the observed satellites in the set of satellites having an altitude greater than the corresponding altitude threshold as the visible satellites observed by the current epoch at the candidate location.
For example, referring to FIG. 8, FIG. 8 illustrates a schematic diagram of a visual satellite corresponding to a determination of a candidate position in one embodiment. It can be seen that the altitude between candidate position 802 and satellite 804 is 806, the altitude threshold determined by occlusion boundary position 810 of candidate position 802 and target occlusion object 808 is 812, altitude 806 is greater than altitude threshold 812, and satellite 804 is the visible satellite to which candidate position 802 corresponds.
In this embodiment, based on the candidate position and the target blocking object on the azimuth angle of each observation satellite, the height angle threshold between the candidate position and each target blocking object is determined, and the visible satellite corresponding to the candidate position is determined by comparing the height angle between the candidate position and each observation satellite with the corresponding height angle threshold, so that the accuracy of identifying the visible satellite is improved, and then the target position is screened based on the visible satellite corresponding to the candidate position, so that the screening accuracy of the target position can be improved.
In one embodiment, the method further comprises: determining the signal-to-noise ratio corresponding to the visible satellite observed by the current epoch in the candidate position; determining the number of satellites with signal-to-noise ratios greater than a preset threshold in the visible satellites; determining satellite visibility corresponding to the candidate position according to the number of visible satellites comprises: determining satellite visibility degrees corresponding to candidate positions according to a first number of satellites with signal-to-noise ratios larger than a preset threshold value in the visible satellites, wherein the satellite visibility degrees are positively correlated with the first number; or determining the satellite visibility corresponding to the candidate position according to the second number of satellites with signal to noise ratios smaller than or equal to a preset threshold value in the satellites except the visible satellites in the satellite set, wherein the satellite visibility is inversely related to the second number.
Where the signal-to-noise ratio is the ratio between the received power and the noise power, and is proportional to the quality of the satellite signal.
In one embodiment, the target device determines the signal-to-noise ratio of the satellite signals observed by the current epoch based on the satellite signals received by the current epoch, and further determines the signal-to-noise ratio of the visible satellites corresponding to each candidate location. Optionally, the target device reads original observation data corresponding to the satellite signals observed by the current epoch in the global satellite navigation system chip through the application program interface, and extracts the signal-to-noise ratio of the satellite signals from the original observation data. For example, the signal-to-noise ratio of the satellite signal observed by the current epoch is obtained from the GNSS Measurement.
In one embodiment, in a shadow matching (shadow matching) algorithm, if the signal-to-noise ratio of the satellite signal received by the target device is greater than a preset threshold, it is determined that the satellite signal is directly received in the unobstructed state, and if the signal-to-noise ratio of the satellite signal received by the target device is less than or equal to the preset threshold, it is determined that the satellite signal is received after being reflected or diffracted.
In one embodiment, the target device determines the visible satellites corresponding to each candidate position of the current epoch, and determines the satellite visibility corresponding to the candidate position according to the number of satellites in the visible satellites with signal to noise ratios greater than a preset threshold. Optionally, the target device scores each candidate position according to the number of satellites with signal to noise ratios greater than a preset threshold in the visible satellites corresponding to each candidate position, for example, scores the satellites with signal to noise ratios greater than the preset threshold in the visible satellites corresponding to the candidate positions, takes the score corresponding to each candidate position as the satellite visibility degree corresponding to each candidate position, and determines the target position from the candidate positions according to the satellite visibility degree.
In one embodiment, the target device determines the satellite visibility corresponding to the candidate position according to the number of satellites in the set of satellites, except for the visible satellites, with a signal-to-noise ratio less than or equal to a preset threshold. Optionally, the target device scores each candidate position according to the number of invisible satellites in the satellite set, wherein the signal-to-noise ratio of the invisible satellites is smaller than or equal to a preset threshold value, for example, the invisible satellites are scored for negative scores, the score corresponding to each candidate position is used as the satellite visibility corresponding to each candidate position, and the target position is determined from the candidate positions according to the satellite visibility.
In one embodiment, the target device determines satellite visibility levels corresponding to the candidate locations, ranks the candidate locations according to the determined satellite visibility levels, for example, ranks from high to low or ranks from low to high, and takes the candidate location with the greatest satellite visibility level as the target location.
In this embodiment, the target position is screened from the candidate positions based on the magnitude relation between the signal-to-noise ratio of the visible satellite corresponding to each candidate position and the preset threshold, so that the screening accuracy of the target position can be improved.
In one embodiment, referring to fig. 9, fig. 9 shows a schematic flow chart of determining a visible satellite corresponding to a candidate position in one embodiment. It can be seen that the target device acquires satellite signals received in the current epoch, and determines candidate positions corresponding to the area where the target device of the current epoch is located according to the satellite signals; determining satellite positions of all observation satellites in the current epoch according to satellite signals received in the current epoch; for each candidate position, calculating azimuth angles between the candidate position and each observation satellite according to the current epoch candidate position and satellite positions of each observation satellite, respectively determining target shielding objects between the candidate position and each observation satellite on the azimuth angles of the candidate position and each observation satellite, determining boundary positions of each target shielding object according to the three-dimensional model of the city, calculating an altitude angle between the candidate position and each target shielding object according to the boundary positions of the candidate position and each target shielding object as an altitude angle threshold value, calculating an altitude angle between the current epoch candidate position and each observation satellite, comparing the altitude angle between the candidate position and each observation satellite with a corresponding altitude angle threshold value, and taking the observation satellite with an altitude angle larger than the corresponding altitude angle threshold value in the satellite set as a visible satellite corresponding to the candidate position; and determining the signal-to-noise ratio of the visible satellites corresponding to the current epoch candidate positions, scoring each candidate position according to the number of satellites with signal-to-noise ratios greater than a preset threshold value in the visible satellites corresponding to each candidate position, for example, scoring the satellites with signal-to-noise ratios greater than the preset threshold value in the visible satellites corresponding to the candidate positions, taking the score corresponding to each candidate position as the satellite visibility degree corresponding to each candidate position, and determining the target position from the candidate positions according to the satellite visibility degree.
In this embodiment, the target position is obtained by screening from each candidate position corresponding to the region where the current epoch target device is located, and then the visible satellite corresponding to the target position is used for positioning.
In one embodiment, the target device determines satellite positions of respective observed satellites of the current epoch based on satellite signals received at the current epoch; for each candidate position, calculating azimuth angles between the candidate position and each observation satellite according to the current epoch candidate position and the satellite positions of each observation satellite; respectively determining target shielding objects between the candidate positions and each observation satellite on azimuth angles of the candidate positions and each observation satellite, and calculating a height angle between the candidate positions and each target shielding object as a height angle threshold; calculating the height angle between the current epoch candidate position and each observation satellite, comparing the height angle between the candidate position and each observation satellite with a corresponding height angle threshold value, and taking the observation satellite with the height angle larger than the corresponding height angle threshold value in the satellite set as the target satellite corresponding to the candidate position; and determining the signal-to-noise ratio of the target satellite corresponding to the current epoch candidate position, and taking the target satellite with the signal-to-noise ratio larger than a preset threshold value as the visible satellite corresponding to the current epoch candidate position.
In this embodiment, the height angle threshold between the candidate position and each target shielding object is determined based on the candidate position and the target shielding object on the azimuth of each observation satellite, the target satellite corresponding to the candidate position is determined by comparing the height angle between the candidate position and each observation satellite with the corresponding height angle threshold, and the visible satellite corresponding to the candidate position is determined based on the magnitude relation between the signal-to-noise ratio of the target satellite corresponding to the candidate position and the preset threshold, so that the accuracy of identifying the visible satellite is improved.
In one embodiment, the method further comprises: acquiring a satellite set observed by a current epoch reference base station; determining an azimuth angle of a reference base station and a target shielding object positioned on the azimuth angle of the reference base station, and calculating a height angle between the reference base station and the target shielding object as a height angle threshold; calculating an altitude angle between a reference base station and each satellite in the satellite set; and taking satellites with the altitude angle larger than the altitude angle threshold value in the satellite set as visible satellites observed by the current epoch reference base station.
In one embodiment, the target device may receive the visible satellites observed with reference to the current epoch transmitted by the base station, followed by subsequent data resolution steps. The target device may also receive satellite observations sent by the reference base station, determine the visible satellites observed by the current epoch of the reference base station based on the satellite observations, and then perform subsequent data resolution steps.
The step of acquiring the satellite set observed by the current epoch reference base station may refer to the step of acquiring the satellite set observed by the current epoch target device; regarding the step of determining the azimuth angle of the reference base station and the target shielding object located at the azimuth angle of the reference base station, calculating the altitude between the reference base station and the target shielding object as the altitude threshold, the step of determining the azimuth angle of the candidate position and the target shielding object located at the azimuth angle with reference to each candidate position, and calculating the altitude between the candidate position and the target shielding object as the altitude threshold; the step of calculating the altitude between the reference base station and each satellite in the satellite set may refer to the step of calculating the altitude between the candidate position and each satellite in the satellite set, and will not be described herein.
In one embodiment, the target device determines satellite positions of each observation satellite in the current epoch according to satellite signals received by the reference base station in the current epoch; calculating azimuth angles between the reference base station and each observation satellite according to satellite positions of the current epoch reference base station and each observation satellite; respectively determining target shielding objects between the reference base station and each observation satellite on azimuth angles of the reference base station and each observation satellite, and calculating a height angle between the reference base station and each target shielding object as a height angle threshold; calculating the height angle between the current epoch reference base station and each observation satellite, comparing the height angle between the reference base station and each observation satellite with the corresponding height angle threshold, and taking the observation satellite with the height angle larger than the corresponding height angle threshold in the satellite set as the target satellite corresponding to the reference base station; and determining the signal-to-noise ratio of the target satellite corresponding to the current epoch reference base station, and taking the target satellite with the signal-to-noise ratio larger than a preset threshold value as the visible satellite corresponding to the current epoch reference base station.
In this embodiment, the visible satellite observed by the current epoch at the target position and the visible satellite observed by the reference base station are respectively acquired, and then the double-difference pseudo-range and the double-difference frequency shift are calculated based on the target visible satellite observed by the current epoch and the visible satellite observed by the reference base station to perform positioning, so that the calculation amount in the positioning process can be reduced due to the reduction of the estimation of the clock difference parameter and the Zhong Piao parameter.
In one embodiment, the method further comprises: acquiring real-time satellite state information corresponding to a target visible satellite observed by current epoch target equipment; according to the real-time satellite state information, determining an observed pseudo range between the target position and each target visible satellite; acquiring reference satellite state information corresponding to a target visible satellite observed by a current epoch reference base station; and calculating a reference pseudo-range between the reference base station and each target visible satellite according to the reference satellite state information.
In one embodiment, for each target visible satellite, the target device determines an observed pseudorange between a current epoch target position and the target visible satellite based on the observed satellite signals, and obtains a reference pseudorange between the current epoch reference base station and the target visible satellite from the reference base station. Then, the target device extracts a first target visible satellite and a second target visible satellite from the target visible satellites, calculates a first difference value between an observed pseudo-range of a current epoch target position for the first target visible satellite and a reference pseudo-range of a current epoch reference base station for the first target visible satellite, calculates a second difference value between an observed pseudo-range of the current epoch target position for the second target visible satellite and a reference pseudo-range of the current epoch reference base station for the second target visible satellite, and calculates a difference value between the first difference value and the second difference value to obtain a double-difference pseudo-range of the current epoch.
In one embodiment, the pseudoranges may be calculated by the following equation:
wherein ,
representing a pseudorange between the receiver r and the satellite s; />
Representing the geometrical distance between the receiver r and the satellite s; c represents the speed of light; dt (dt) r Representing receiver clock error, dt s Representing satellite clock differences; d, d r Representing the hardware delay of the receiver r, d s Representing the hardware delay of satellite s; />
Representing ionospheric delay, +.>
Representing tropospheric delay; />
And represents errors such as multipath, noise, etc. of the pseudorange and carrier phase observations.
In one embodiment, calculating the double-difference pseudorange for the current epoch based on the observed pseudorange between the target position for the current epoch and the target satellites in view and the reference pseudorange between the reference base station and the target satellites in view comprises:
the epoch target device a observes pseudoranges at the target location to the target satellites j in view,
representing a reference pseudo range of the current epoch reference base station b to the target visible satellite j; />
An observed pseudo-range representing the current epoch target device a at the target position to the target visible satellite k,/->
Indicating the current epoch reference base b is +.>
Is a reference pseudorange to (a); />
Representing the double-difference geometric distance between the current epoch target device a and the reference base station b; />
Representing the double difference error of the current epoch target device a and the reference base station b, which is the correlation error of the pseudorange and carrier phase observations.
The following describes the derivation of the formula for calculating the double difference pseudorange:
in one embodiment, referring to FIG. 10, FIG. 10 illustrates a schematic diagram of a double difference pseudorange for a current epoch in one embodiment. Here, the example is given in which the target device a and the reference base station b observe the target visible satellite k and the target visible satellite j at the same time in the current epoch:
the target equipment a and the reference base station b observe a target visible satellite k at the same time in the current epoch, and an observed pseudo-range of the target equipment a on the target visible satellite k at the target position in the current epoch is calculated
Reference pseudo-range +.f for target visible satellite k with current epoch reference base station b>
First difference ∈>
The target equipment a and the reference base station b observe a target visible satellite j at the same time of the current epoch, and an observed pseudo-range of the target equipment a on the target visible satellite j at the target position of the current epoch is calculated
Reference pseudo-range +.f for target visible satellite j with current epoch reference base station b>
Second difference ∈>
Then, calculate the second difference
From the first difference->
The difference value between the two time periods is used for obtaining the double-difference pseudo-range of the current epoch
Considering that the distance between the target device a and the reference base station b is relatively close, the ionosphere and troposphere residuals can be ignored, and the double-difference pseudo-range of the current epoch 
Can be simplified expressed as:
wherein ,
a double-difference pseudo range representing the current epoch target device a and the reference base station b; />
Representing the double-difference geometric distance between the current epoch target device a and the reference base station b; />
Representing the double difference error of the current epoch target device a and the reference base station b, which is the correlation error of the pseudorange and carrier phase observations.
In one embodiment, the target device calculates the position of the target device in the current epoch based on the double-difference pseudoranges of the current epoch. For example, the target device may calculate the location of the target device at the current epoch based on the double-differential pseudoranges calculated at the plurality of frequencies for the current epoch.
In this embodiment, the double-difference pseudo range between the current epoch target device and the reference base station is calculated to perform positioning, and the difference mode can effectively eliminate the satellite clock difference and the receiver clock difference, so that the calculation amount in the positioning process can be reduced due to the reduction of the estimation of the clock difference parameters.
In one embodiment, the method further comprises: acquiring a first carrier phase observation value corresponding to a target visible satellite observed by target equipment of a current epoch, and a second carrier phase observation value observed by the target equipment determined in the previous epoch to the target visible satellite, and calculating an observation frequency shift corresponding to the current epoch; and acquiring a first carrier phase reference value observed by the reference base station of the current epoch for the target visible satellite, and calculating a reference frequency shift corresponding to the current epoch according to a second carrier phase reference value observed by the reference base station determined in the previous epoch for the target visible satellite.
In one embodiment, for each target visible satellite, the target device determines a carrier phase observation value of the current epoch target visible satellite, and calculates a difference between the carrier phase observation value and the carrier phase observation value observed by the previous epoch target device for the target visible satellite, so as to obtain an observation frequency shift corresponding to the current epoch. The target equipment acquires a carrier phase reference value observed by a current epoch of a reference base station for the target visible satellite and a carrier phase reference value observed by a previous epoch reference base station for the target visible satellite, calculates the difference between the two values, and acquires a reference frequency shift corresponding to the current epoch. Then, the target device extracts a first target visible satellite and a second target visible satellite from the target visible satellites, calculates a first difference value between the current epoch target position and the reference frequency shift of the current epoch reference base station for the first target visible satellite, calculates a second difference value between the current epoch target position and the reference frequency shift of the current epoch reference base station for the second target visible satellite, and calculates the first difference value and the second difference value, so as to obtain a double-difference frequency shift of the current epoch.
In one embodiment, the Doppler shift may be calculated by the following equation:
wherein ,
representing the Doppler shift of the receiver r to satellite s at the current epoch t; />
Indicating that the receiver r is inDoppler observation of the current epoch t to satellite s; lambda is the frequency wavelength; />
Representing the carrier phase observations of the receiver r for satellite s at the current epoch t +.>
Representing the carrier phase observations of the receiver r for satellite s at the previous epoch t-1; Δt represents the time interval between the current epoch and the previous epoch.
In one embodiment, the relationship between Doppler shift and receiver speed can be expressed by the following equation:
wherein ,
representing the Doppler shift of the receiver r to satellite s at the current epoch t; />
Cosine +.>
vs represents the velocity of satellite s; v r Representing the speed of the receiver r, which may be expressed in particular as [ vx ] r ,vy r ,vz r ]The method comprises the steps of carrying out a first treatment on the surface of the b represents Zhong Piao of the receiver r; />
And represents errors such as multipath, noise, etc. of the pseudorange and carrier phase observations.
In one embodiment, calculating the double difference frequency shift for the current epoch based on the observed frequency shift between the current epoch target position and the target satellite and the reference frequency shift between the reference base station and the target satellite comprises:
wherein ,
representing a double difference frequency shift of the current epoch target device a and the reference base station b; />
Indicating the observed frequency shift of the current epoch target device a to the target visible satellite j at the target position,/>
Representing the reference frequency shift of the current epoch reference base station b to the target visible satellite j; />
Representing the observed frequency shift of the current epoch target device a to the target satellite k at the target location,
representing the reference frequency shift of the current epoch reference base station b to the target visible satellite j.
wherein ,
cosine and +.f representing the direction of the connection of the target device a to the target visible satellite j at the target position>
The cosine of the connection line direction of the target equipment a at the target position and the target visible satellite k is represented; v a Representing the speed of the target device a; />
Cosine representing the direction of connection of reference base station b to target visible satellite j, < >>
Cosine of the connection line direction of the reference base station b and the target visible satellite k is shown; v j Representing the velocity, v, of the target visible satellite j k Representing the velocity of the target visible satellite k; />
Representing the double difference error of the target device a and the reference base station b in the current epoch, which is the correlation error of the pseudorange and the carrier phase observations.
The following describes the derivation of the formula for calculating the double difference frequency shift:
in one embodiment, referring to FIG. 11, FIG. 11 shows a schematic diagram of calculating a double difference frequency shift for a current epoch in one embodiment. Here, the example is given in which the target device a and the reference base station b observe the target visible satellite k and the target visible satellite j at the same time in the current epoch:
The target equipment a and the reference base station b observe the target visible satellite k in the current epoch at the same time, and the observation frequency shift of the target equipment a of the current epoch to the target visible satellite k at the target position is calculated
Reference frequency shift of target visible satellite k with current epoch reference base station b>
First difference ∈>
Target device a and reference base station b are inThe current epoch simultaneously observes the target visible satellite j, and the observation frequency shift of the target equipment a of the current epoch on the target visible satellite j at the target position is calculated
Reference frequency shift of the target visible satellite j with the current epoch reference base station b +.>
Second difference ∈>
Then, calculate the second difference
From the first difference->
The difference value between the two is obtained to obtain the double difference frequency shift of the current epoch
If the reference base station is a universal satellite tracking reference station, then the velocity v of the reference base station b Zero, so the double difference frequency shift of the current epoch
Can be expressed as:
wherein ,
representing a double difference frequency shift of the current epoch target device a and the reference base station b; />
Cosine and +.f representing the direction of the connection of the target device a to the target visible satellite j at the target position>
The cosine of the connection line direction of the target equipment a at the target position and the target visible satellite k is represented; va represents the speed of the target device a; />
Cosine representing the direction of connection of reference base station b to target visible satellite j, < > >
Cosine of the connection line direction of the reference base station b and the target visible satellite k is shown; v j Representing the velocity, v, of the target visible satellite j k Representing the velocity of the target visible satellite k; />
Representing the double difference error of the target device a and the reference base station b in the current epoch, which is the correlation error of the pseudorange and the carrier phase observations.
In this embodiment, the dual difference frequency shift between the current epoch target device and the reference base station is calculated to perform positioning, and the differential manner can effectively eliminate the satellite Zhong Piao and the receiver Zhong Piao, so that the calculation amount in the positioning process can be reduced due to the reduction of the estimation of the clock drift parameters.
In one embodiment, adding an end variable node to a factor graph optimized by a previous epoch according to a double-difference pseudo range of a current epoch and a double-difference frequency shift of the current epoch to obtain a factor graph corresponding to the current epoch, adjusting the factor graph corresponding to the current epoch with the posterior probability maximization of the factor graph corresponding to the current epoch as a target to obtain the factor graph optimized by the current epoch, and generating positioning information of the current epoch of the target device based on the end variable node in the factor graph optimized by the current epoch, including: taking the double-difference pseudo range of the current epoch and the double-difference frequency shift of the current epoch as factor nodes, calculating the position of the target equipment in the current epoch according to the double-difference pseudo range of the current epoch, calculating the speed of the target equipment in the current epoch according to the double-difference frequency shift of the current epoch, and adding an end variable node to the factor graph optimized by the previous epoch according to the position of the current epoch and the speed of the current epoch to obtain a factor graph corresponding to the current epoch; and adjusting the value of each variable node in the factor graph corresponding to the current epoch with the aim of maximizing the posterior probability calculated based on the factor node and the variable node in the factor graph corresponding to the current epoch, obtaining the factor graph optimized by the current epoch, and generating the positioning information of the current epoch of the target equipment based on the position represented by the last variable node in the factor graph optimized by the current epoch.
In one embodiment, the method further comprises: calculating a first conditional probability among variable nodes in a factor graph corresponding to the current epoch; calculating a second conditional probability between each variable node and a corresponding factor node in the factor graph corresponding to the current epoch; and calculating the posterior probability of the factor graph corresponding to the current epoch according to the first conditional probabilities and the second conditional probabilities.
In one embodiment, referring to FIG. 12, FIG. 12 illustrates a schematic diagram of a factor graph corresponding to a current epoch in one embodiment. It can be seen that the factor graph corresponding to the current epoch includes a variable node X 1 、…、X n-1 、X n, wherein Xn And a variable node newly added for the current epoch. Each variable node has a corresponding factor node, e.g. variable node X n Corresponding factor node Z n 。
In one embodiment, there is a dependency relationship between the various variable nodes, e.g., variable node X, in the factor graph corresponding to the current epoch n Dependent on variable node X n-1 Therefore, a first condition between variable nodes in the factor graph is calculatedProbability: p (X) 2 |X 1 )、…P(X n |X n-1 )。
The dependency relationship between each variable node in the factor graph corresponding to the current epoch can be expressed by the following formula:
wherein ,Xn Variable node, X, representing the current epoch n-1 A variable node representing a previous epoch of the current epoch; x, y, z represent variable node X n Is a position of (2); v x 、v y 、v z Representing variable node X n Is a speed of (2); dt represents the time interval between the current epoch and the previous epoch.
In the factor graph corresponding to the current epoch, each variable node depends on the corresponding factor node, so that a second conditional probability between each variable node and the corresponding factor node in the factor graph is calculated: p (Z) 1 |X 1 )、…P(Z n |X n )。
The target device may adopt a sliding window manner, take the posterior probability obtained by calculating based on the factor node and the variable node in the factor graph corresponding to the current epoch as a target, adjust the value of each variable node in the factor graph corresponding to the current epoch, and obtain the factor graph optimized by the current epoch, and may be represented by the following formula:
{X}＝argmax(X 0 )ΠP(X n |X n-1 )ΠP(Z n |X n )
wherein { X } represents the optimal value of each variable node in the sliding window; (X) 0 ) Representing the initial value of each variable node in the sliding window before the current epoch optimization; pi P (X) n |X n-1 ) A cumulative multiplication result representing a first conditional probability between variable nodes within the sliding window; pi P (Z) n |X n ) And the cumulative multiplication result of the second conditional probability between each variable node and the corresponding factor node in the sliding window is represented.
In the embodiment, the position information of the target equipment obtained based on satellite observation data calculation is optimized through a factor graph algorithm, so that the positioning accuracy can be improved; the double-difference pseudo-range and double-difference frequency shift reduce the estimation of the clock difference parameter and the Zhong Piao parameter, so that the calculated amount in the positioning process can be reduced; the factor graph is optimized by adopting the sliding window, so that the precision can be ensured, and the timeliness of real-time positioning at the terminal can be ensured.
In one embodiment, as shown in fig. 13, a positioning method is provided, which is described by taking an example that the method is applied to the terminal 102 (hereinafter referred to as a target device) in fig. 1, and includes the following steps:
In step 1304, satellite positions of each of the observed satellites of the current epoch are determined from the satellite signals received at the current epoch.
In step 1314, a first conditional probability among the variable nodes in the factor graph corresponding to the current epoch is calculated, a second conditional probability among the variable nodes and the corresponding factor nodes in the factor graph corresponding to the current epoch is calculated, and a posterior probability of the factor graph corresponding to the current epoch is calculated according to the first conditional probabilities and the second conditional probabilities.
In this embodiment, on the one hand, based on a target shielding object on an azimuth angle between a candidate position corresponding to an area where a current epoch target device is located and a satellite observed by the target device, determining a satellite visibility corresponding to the candidate position, determining a target position from the candidate positions according to the satellite visibility, and participating in a subsequent positioning process in a target visible satellite observed by the current epoch together with a reference base station at the target position, wherein satellites which cannot be directly observed by the target device are eliminated, so that accuracy of subsequent positioning can be improved; on the other hand, adding an end variable node to the factor graph optimized by the previous epoch according to the double-difference pseudo range of the current epoch and the double-difference frequency shift of the current epoch to obtain a factor graph corresponding to the current epoch, adjusting the factor graph corresponding to the current epoch with the posterior probability maximization of the factor graph corresponding to the current epoch as a target to obtain the factor graph optimized by the current epoch, generating positioning information of the current epoch of the target equipment based on the end variable node in the factor graph optimized by the current epoch, optimizing the position information of the target equipment based on satellite observation data solution through a factor graph algorithm, and improving the positioning accuracy.
It should be understood that, although the steps in the flowcharts related to the above embodiments are sequentially shown as indicated by arrows, these steps are not necessarily sequentially performed in the order indicated by the arrows. The steps are not strictly limited to the order of execution unless explicitly recited herein, and the steps may be executed in other orders. Moreover, at least some of the steps in the flowcharts described in the above embodiments may include a plurality of steps or a plurality of stages, which are not necessarily performed at the same time, but may be performed at different times, and the order of the steps or stages is not necessarily performed sequentially, but may be performed alternately or alternately with at least some of the other steps or stages.
Based on the same inventive concept, the embodiment of the application also provides a positioning device for realizing the positioning method. The implementation of the solution provided by the device is similar to that described in the above method, so the specific limitations in one or more embodiments of the positioning device provided below may be referred to above for limitations of the positioning method, which are not repeated here.
In one embodiment, as shown in fig. 14, there is provided a positioning device comprising: candidate position determination module 1402, target position determination module 1404, visible satellite determination module 1406, computing module 1408, and positioning module 1410, wherein:
a candidate position determining module 1402, configured to determine a candidate position corresponding to an area where the current epoch target device is located;
a target position determining module 1404, configured to determine a satellite visibility degree corresponding to the candidate position based on the current epoch candidate position and a target blocking object on an azimuth angle between satellites observed by the target device, and determine a target position from the candidate positions according to the satellite visibility degree;
a visible satellite determination module 1406 for determining a target visible satellite observed by the current epoch together with the reference base station at the target position;
a calculating module 1408, configured to calculate a double-difference pseudo-range of the current epoch according to an observed pseudo-range between the target position of the current epoch and the target visible satellite and a reference pseudo-range between the reference base station and the target visible satellite, and calculate a double-difference frequency shift of the current epoch according to an observed frequency shift between the target position of the current epoch and the target visible satellite and a reference frequency shift between the reference base station and the target visible satellite;
The positioning module 1410 is configured to add an end variable node to a factor graph optimized by a previous epoch according to the double-difference pseudo range of the current epoch and the double-difference frequency shift of the current epoch, obtain a factor graph corresponding to the current epoch, adjust the factor graph corresponding to the current epoch with the posterior probability maximization of the factor graph corresponding to the current epoch as a target, obtain the factor graph optimized by the current epoch, and generate positioning information of the current epoch of the target device based on the end variable node in the factor graph optimized by the current epoch.
In one embodiment, the candidate position determination module 1402 is further configured to: determining an initial estimated position of the target device; constructing a candidate region by taking the initial estimated position as a center; the candidate region is equally divided into a plurality of candidate locations.
In one embodiment, the target location determination module 1404 is further configured to: acquiring a satellite set observed by current epoch target equipment; for each candidate position, determining an azimuth angle of the candidate position and a target shielding object positioned on the azimuth angle, and calculating a height angle between the candidate position and the target shielding object as a height angle threshold; calculating the altitude between the candidate position and each satellite in the satellite set; satellites with the altitude angle larger than the altitude angle threshold value in the satellite set are used as visible satellites observed by the current epoch in the candidate positions; and determining satellite visibility corresponding to the candidate positions according to the number of the visible satellites.
In one embodiment, the target location determination module 1404 is further configured to: determining the signal-to-noise ratio corresponding to the visible satellite observed by the current epoch in the candidate position; determining the number of satellites with signal-to-noise ratios greater than a preset threshold in the visible satellites; determining satellite visibility degrees corresponding to candidate positions according to a first number of satellites with signal-to-noise ratios larger than a preset threshold value in the visible satellites, wherein the satellite visibility degrees are positively correlated with the first number; or determining the satellite visibility corresponding to the candidate position according to the second number of satellites with signal to noise ratios smaller than or equal to a preset threshold value in the satellites except the visible satellites in the satellite set, wherein the satellite visibility is inversely related to the second number.
In one embodiment, the target location determination module 1404 is further configured to: acquiring a satellite set observed by a current epoch reference base station; determining an azimuth angle of a reference base station and a target shielding object positioned on the azimuth angle of the reference base station, and calculating a height angle between the reference base station and the target shielding object as a height angle threshold; calculating an altitude angle between a reference base station and each satellite in the satellite set; satellites with the altitude angle larger than the altitude angle threshold value in the satellite set are used as visible satellites observed by the current epoch reference base station; the visible satellite determination module 1406 is further configured to: and determining the target visible satellite observed by the current epoch together with the reference base station at the target position according to the intersection set of the visible satellite observed by the current epoch at the target position and the visible satellite observed by the reference base station.
In one embodiment, the computing module 1408 is further to: acquiring real-time satellite state information corresponding to a target visible satellite observed by current epoch target equipment; according to the real-time satellite state information, determining an observed pseudo range between the target position and each target visible satellite; acquiring reference satellite state information corresponding to a target visible satellite observed by a current epoch reference base station; and calculating a reference pseudo-range between the reference base station and each target visible satellite according to the reference satellite state information.
In one embodiment, the computing module 1408 is further to:
In one embodiment, the computing module 1408 is further to: acquiring a first carrier phase observation value corresponding to a target visible satellite observed by target equipment of a current epoch, and a second carrier phase observation value observed by the target equipment determined in the previous epoch to the target visible satellite, and calculating an observation frequency shift corresponding to the current epoch; and acquiring a first carrier phase reference value observed by the reference base station of the current epoch for the target visible satellite, and calculating a reference frequency shift corresponding to the current epoch according to a second carrier phase reference value observed by the reference base station determined in the previous epoch for the target visible satellite.
In one embodiment, the computing module 1408 is further to:
wherein ,
representing a double difference frequency shift of the current epoch target device a and the reference base station b; />
Indicating the observed frequency shift of the current epoch target device a to the target visible satellite j at the target position,/>
Representing the reference frequency shift of the current epoch reference base station b to the target visible satellite j; />
Representing the observed frequency shift of the current epoch target device a to the target satellite k at the target location,
representing the reference frequency shift of the current epoch reference base station b to the target visible satellite j.
wherein ,
cosine and +.f representing the direction of the connection of the target device a to the target visible satellite j at the target position>
The cosine of the connection line direction of the target equipment a at the target position and the target visible satellite k is represented; va represents the speed of the target device a; />
Cosine representing the direction of connection of reference base station b to target visible satellite j, < >>
Cosine of the connection line direction of the reference base station b and the target visible satellite k is shown; v j Representing the velocity, v, of the target visible satellite j k Representing the velocity of the target visible satellite k; />
Representing the double difference error of the target device a and the reference base station b in the current epoch, which is the correlation error of the pseudorange and the carrier phase observations. />
In one embodiment, the positioning module 1410 is further configured to: taking the double-difference pseudo range of the current epoch and the double-difference frequency shift of the current epoch as factor nodes, calculating the position of the target equipment in the current epoch according to the double-difference pseudo range of the current epoch, calculating the speed of the target equipment in the current epoch according to the double-difference frequency shift of the current epoch, and adding an end variable node to the factor graph optimized by the previous epoch according to the position of the current epoch and the speed of the current epoch to obtain a factor graph corresponding to the current epoch; and adjusting the value of each variable node in the factor graph corresponding to the current epoch with the aim of maximizing the posterior probability calculated based on the factor node and the variable node in the factor graph corresponding to the current epoch, obtaining the factor graph optimized by the current epoch, and generating the positioning information of the current epoch of the target equipment based on the position represented by the last variable node in the factor graph optimized by the current epoch.
In one embodiment, the positioning module 1410 is further configured to: calculating a first conditional probability among variable nodes in a factor graph corresponding to the current epoch; calculating a second conditional probability between each variable node and a corresponding factor node in the factor graph corresponding to the current epoch; and calculating the posterior probability of the factor graph corresponding to the current epoch according to the first conditional probabilities and the second conditional probabilities.
The various modules in the positioning device described above may be implemented in whole or in part by software, hardware, and combinations thereof. The above modules may be embedded in hardware or may be independent of a processor in the computer device, or may be stored in software in a memory in the computer device, so that the processor may call and execute operations corresponding to the above modules.
In one embodiment, a computer device is provided, which may be a terminal, and an internal structure diagram thereof may be as shown in fig. 15. The computer device includes a processor, a memory, a communication interface, a display screen, and an input device connected by a system bus. Wherein the processor of the computer device is configured to provide computing and control capabilities. The memory of the computer device includes a non-volatile storage medium and an internal memory. The non-volatile storage medium stores an operating system and a computer program. The internal memory provides an environment for the operation of the operating system and computer programs in the non-volatile storage media. The communication interface of the computer device is used for carrying out wired or wireless communication with an external terminal, and the wireless mode can be realized through WIFI, a mobile cellular network, NFC (near field communication) or other technologies. The computer program is executed by a processor to implement a positioning method.
It will be appreciated by those skilled in the art that the structure shown in fig. 15 is merely a block diagram of a portion of the structure associated with the present application and is not limiting of the computer device to which the present application is applied, and that a particular computer device may include more or fewer components than shown, or may combine certain components, or have a different arrangement of components.
In an embodiment, a computer device is provided, comprising a memory and a processor, the memory having stored therein a computer program, the processor implementing the positioning method of any of the embodiments described above when the computer program is executed.
In one embodiment, a computer readable storage medium is provided, on which a computer program is stored which, when executed by a processor, implements the positioning method of any of the embodiments described above.
In an embodiment, a computer program product is provided, comprising a computer program which, when executed by a processor, implements the positioning method of any of the embodiments described above.
It should be noted that, user information (including but not limited to user equipment information, user personal information, etc.) and data (including but not limited to data for analysis, stored data, presented data, etc.) referred to in the present application are information and data authorized by the user or sufficiently authorized by each party.
Those skilled in the art will appreciate that implementing all or part of the above-described methods in accordance with the embodiments may be accomplished by way of a computer program stored on a non-transitory computer readable storage medium, which when executed may comprise the steps of the embodiments of the methods described above. Any reference to memory, database, or other medium used in the various embodiments provided herein may include at least one of non-volatile and volatile memory. The nonvolatile Memory may include Read-Only Memory (ROM), magnetic tape, floppy disk, flash Memory, optical Memory, high density embedded nonvolatile Memory, resistive random access Memory (ReRAM), magnetic random access Memory (Magnetoresistive Random Access Memory, MRAM), ferroelectric Memory (Ferroelectric Random Access Memory, FRAM), phase change Memory (Phase Change Memory, PCM), graphene Memory, and the like. Volatile memory can include random access memory (Random Access Memory, RAM) or external cache memory, and the like. By way of illustration, and not limitation, RAM can be in the form of a variety of forms, such as static random access memory (Static Random Access Memory, SRAM) or dynamic random access memory (Dynamic Random Access Memory, DRAM), and the like. The databases referred to in the various embodiments provided herein may include at least one of relational databases and non-relational databases. The non-relational database may include, but is not limited to, a blockchain-based distributed database, and the like. The processors referred to in the embodiments provided herein may be general purpose processors, central processing units, graphics processors, digital signal processors, programmable logic units, quantum computing-based data processing logic units, etc., without being limited thereto.
The technical features of the above embodiments may be arbitrarily combined, and all possible combinations of the technical features in the above embodiments are not described for brevity of description, however, as long as there is no contradiction between the combinations of the technical features, they should be considered as the scope of the description.
The foregoing examples represent only a few embodiments of the present application, which are described in more detail and are not thereby to be construed as limiting the scope of the present application. It should be noted that it would be apparent to those skilled in the art that various modifications and improvements could be made without departing from the spirit of the present application, which would be within the scope of the present application. Accordingly, the scope of protection of the present application shall be subject to the appended claims.
Claims (15)
1. A method of positioning, the method comprising:
determining candidate positions corresponding to the areas where the current epoch target devices are located;
determining satellite visibility corresponding to the candidate position based on a target shielding object in an azimuth angle between the candidate position and a satellite observed by the target equipment in the current epoch, and determining a target position from the candidate position according to the satellite visibility; determining a target visible satellite observed by the current epoch together with a reference base station at the target position;
Calculating double-difference pseudo-ranges of the current epoch according to the observed pseudo-ranges between the target position of the current epoch and the target visible satellite and the reference pseudo-ranges between the reference base station and the target visible satellite, and calculating double-difference frequency shifts of the current epoch according to the observed frequency shifts between the target position of the current epoch and the target visible satellite and the reference frequency shifts between the reference base station and the target visible satellite;
adding an end variable node to the factor graph optimized by the previous epoch according to the double-difference pseudo range of the current epoch and the double-difference frequency shift of the current epoch to obtain a factor graph corresponding to the current epoch, adjusting the factor graph corresponding to the current epoch with the posterior probability maximization of the factor graph corresponding to the current epoch as a target to obtain the factor graph optimized by the current epoch, and generating the positioning information of the current epoch of the target equipment based on the end variable node in the factor graph optimized by the current epoch.
2. The method of claim 1, wherein determining the candidate location corresponding to the area in which the current epoch target device is located comprises:
determining an initial estimated position of the target device;
Constructing a candidate region by taking the initial estimated position as a center;
the candidate region is equally divided into a plurality of candidate positions.
3. The method of claim 1, wherein the determining the satellite visibility corresponding to the candidate location based on the target occluding object in azimuth between the candidate location for the current epoch and the satellite observed by the target device comprises:
acquiring a satellite set observed by the target equipment in the current epoch;
for each candidate position, determining an azimuth angle of the candidate position and a target shielding object positioned on the azimuth angle, and calculating an altitude angle between the candidate position and the target shielding object as an altitude angle threshold;
calculating an altitude angle between the candidate position and each satellite in the satellite set;
taking the satellites with the altitude angles larger than the altitude angle threshold value in the satellite set as visible satellites observed by the current epoch at the candidate positions;
and determining satellite visibility corresponding to the candidate position according to the number of the visible satellites.
4. A method according to claim 3, characterized in that the method further comprises:
Determining the signal-to-noise ratio corresponding to the visible satellite observed by the current epoch at the candidate position;
determining the number of satellites in the visible satellites, wherein the signal-to-noise ratio of the satellites is greater than a preset threshold;
the determining the satellite visibility corresponding to the candidate position according to the number of the visible satellites comprises:
determining satellite visibility degrees corresponding to the candidate positions according to a first number of satellites in the visible satellites, wherein the signal-to-noise ratio of the satellites is larger than a preset threshold value, and the satellite visibility degrees are positively correlated with the first number; or determining the satellite visibility corresponding to the candidate position according to a second number of satellites with signal-to-noise ratios smaller than or equal to the preset threshold value in satellites except the visible satellites in the satellite set, wherein the satellite visibility is inversely related to the second number.
5. The method according to claim 1, wherein the method further comprises:
acquiring a satellite set observed by a current epoch reference base station;
determining an azimuth angle of the reference base station and a target shielding object positioned on the azimuth angle of the reference base station, and calculating a height angle between the reference base station and the target shielding object as a height angle threshold;
Calculating an altitude angle between the reference base station and each satellite in the satellite set;
taking the satellites with the altitude angle larger than the altitude angle threshold value in the satellite set as visible satellites observed by the reference base station in the current epoch;
the determining the target visible satellite observed by the current epoch at the target position together with the reference base station comprises the following steps:
and determining the target visible satellite observed by the current epoch together with the reference base station at the target position according to the intersection set of the visible satellite observed by the current epoch at the target position and the visible satellite observed by the reference base station.
6. The method according to claim 1, wherein the method further comprises:
acquiring real-time satellite state information corresponding to the target visible satellite observed by the target equipment in the current epoch;
determining an observed pseudo range between the target position and each target visible satellite according to the real-time satellite state information;
acquiring reference satellite state information corresponding to the target visible satellite observed by the reference base station in the current epoch;
and calculating a reference pseudo range between the reference base station and each target visible satellite according to the reference satellite state information.
7. The method of claim 6, wherein said calculating a double-difference pseudorange for a current epoch based on an observed pseudorange between the target position and the target visible satellite for the current epoch and a reference pseudorange between the reference base station and the target visible satellite comprises:
wherein ,
a double-difference pseudo range representing the current epoch target device a and the reference base station b; />
An observed pseudo-range representing the current epoch target device a at the target position to the target visible satellite j,/>
Representing a reference pseudo range of the current epoch reference base station b to the target visible satellite j; />
An observed pseudo-range representing the current epoch target device a at the target position to the target visible satellite k,/->
Representing a reference pseudo range of the current epoch reference base station b to the target visible satellite j; />
Representing the double-difference geometric distance between the current epoch target device a and the reference base station b; />
Representing the double difference error of the current epoch target device a and the reference base station b, which is the correlation error of the pseudorange and carrier phase observations.
8. The method according to claim 1, wherein the method further comprises:
acquiring a first carrier phase observation value corresponding to the target visible satellite observed by the target equipment in a current epoch and a second carrier phase observation value, which is determined in a previous epoch, observed by the target equipment on the target visible satellite, and calculating an observation frequency shift corresponding to the current epoch;
And acquiring a first carrier phase reference value observed by the reference base station for the target visible satellite in the current epoch and a second carrier phase reference value observed by the reference base station for the target visible satellite in the previous epoch, and calculating the reference frequency shift corresponding to the current epoch.
9. The method of claim 8, wherein the calculating the double difference frequency shift for the current epoch based on the observed frequency shift between the target position for the current epoch and the target satellites in view and the reference frequency shift between the reference base station and the target satellites in view comprises:
wherein ,
representing a double difference frequency shift of the current epoch target device a and the reference base station b; />
Indicating the observed frequency shift of the current epoch target device a to the target visible satellite j at the target position,/>
Representing the reference frequency shift of the current epoch reference base station b to the target visible satellite j; />
Representing the observed frequency shift of the current epoch target device a at the target position for the target visual satellite k,/>
Representing the reference frequency shift of the current epoch reference base station b to the target visible satellite j.
wherein ,
cosine and +.f representing the direction of the connection of the target device a to the target visible satellite j at the target position >
The cosine of the connection line direction of the target equipment a at the target position and the target visible satellite k is represented; v a Representing the speed of the target device a; />
Cosine representing the direction of connection of reference base station b to target visible satellite j, < >>
Cosine of the connection line direction of the reference base station b and the target visible satellite k is shown; v j Representing the velocity, v, of the target visible satellite j k Representing the velocity of the target visible satellite k; />
Representing the double difference error of the target device a and the reference base station b in the current epoch, which is the correlation error of the pseudorange and the carrier phase observations.
10. The method according to any one of claims 1 to 9, wherein the adding an end variable node to the factor graph optimized by the previous epoch according to the double-difference pseudo-range of the current epoch and the double-difference frequency shift of the current epoch to obtain a factor graph corresponding to the current epoch, adjusting the factor graph corresponding to the current epoch with the posterior probability maximization of the factor graph corresponding to the current epoch as a target, obtaining a factor graph optimized by the current epoch, and generating the positioning information of the current epoch of the target device based on the end variable node in the factor graph optimized by the current epoch includes:
taking the double difference pseudo range of the current epoch and the double difference frequency shift of the current epoch as factor nodes, calculating the position of the target equipment in the current epoch according to the double difference pseudo range of the current epoch, calculating the speed of the target equipment in the current epoch according to the double difference frequency shift of the current epoch, and adding an end variable node to a factor graph optimized for the previous epoch according to the position of the current epoch and the speed of the current epoch to obtain a factor graph corresponding to the current epoch;
And adjusting the value of each variable node in the factor graph corresponding to the current epoch with the aim of maximizing posterior probability calculated based on the factor node and the variable node in the factor graph corresponding to the current epoch, obtaining the factor graph optimized by the current epoch, and generating the positioning information of the current epoch of the target equipment based on the position represented by the last variable node in the factor graph optimized by the current epoch.
11. The method according to claim 10, wherein the method further comprises:
calculating a first conditional probability among variable nodes in a factor graph corresponding to the current epoch;
calculating a second conditional probability between each variable node and a corresponding factor node in the factor graph corresponding to the current epoch;
and calculating the posterior probability of the factor graph corresponding to the current epoch according to the first conditional probability and the second conditional probability.
12. A positioning device, the device comprising:
the candidate position determining module is used for determining candidate positions corresponding to the area where the current epoch target device is located;
the target position determining module is used for determining satellite visibility corresponding to the candidate position based on a target shielding object in azimuth angle between the candidate position of the current epoch and a satellite observed by the target equipment, and determining a target position from the candidate position according to the satellite visibility;
The visible satellite determining module is used for determining a target visible satellite observed by the current epoch together with the reference base station at the target position;
the calculation module is used for calculating double-difference pseudo ranges of the current epoch according to the observed pseudo ranges between the target position and the target visible satellite of the current epoch and the reference pseudo ranges between the reference base station and the target visible satellite, and calculating double-difference frequency shifts of the current epoch according to the observed frequency shifts between the target position and the target visible satellite of the current epoch and the reference frequency shifts between the reference base station and the target visible satellite;
the positioning module is used for adding an end variable node to the factor graph optimized by the previous epoch according to the double-difference pseudo range of the current epoch and the double-difference frequency shift of the current epoch to obtain a factor graph corresponding to the current epoch, adjusting the factor graph corresponding to the current epoch with the posterior probability maximization of the factor graph corresponding to the current epoch as a target to obtain the factor graph optimized by the current epoch, and generating positioning information of the current epoch of the target equipment based on the end variable node in the factor graph optimized by the current epoch.
13. A computer device comprising a memory and a processor, the memory storing a computer program, characterized in that the processor implements the steps of the method of any one of claims 1 to 11 when the computer program is executed.
14. A computer readable storage medium, on which a computer program is stored, characterized in that the computer program, when being executed by a processor, implements the steps of the method of any of claims 1 to 11.
15. A computer program product comprising a computer program, characterized in that the computer program, when being executed by a processor, implements the steps of the method of any one of claims 1 to 11.
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