An automatic driving navigation and positioning system and method based on low-orbit satellite communication and navigation integration

Abstract

The present invention discloses an automatic driving navigation and positioning system and method based on low-orbit satellite integrated communication and navigation, comprising a ground part, a space part and a vehicle-mounted integrated communication and navigation terminal: the ground part monitors satellite data, generates navigation messages and GNSS complete enhancement information using the monitoring data, the space part receives the navigation messages of the ground part, modulates and generates low-orbit satellite and GNSS navigation signals, and broadcasts the navigation signals to the vehicle-mounted integrated communication and navigation terminal, the low-orbit satellite forwards the position information from the vehicle-mounted integrated communication and navigation terminal and the GNSS complete enhancement information of the ground part, the vehicle-mounted integrated communication and navigation terminal receives the GNSS navigation signal, obtains the coarse-precision position of the terminal, and sends the position to the low-orbit satellite of the space part, and simultaneously receives the low-orbit satellite navigation signal, demodulates in real time to obtain the message information and the low-orbit satellite observation quantity, combines the GNSS navigation signal and the GNSS complete enhancement information, calculates and obtains high-precision terminal position information, and realizes high-precision positioning in areas where mobile signals cannot reach.

Description

Technical Field

[0001] The present invention relates to the field of navigation and positioning, and in particular to a low-orbit satellite-based integrated automatic driving navigation and positioning system and method. Background Art

[0002] In the implementation of autonomous driving navigation, in order to meet the needs of vehicles to obtain and maintain lane-level positioning accuracy under conditions such as occlusion, interruption, and interference, GNSS RTK is generally used in combination with inertial navigation devices and other sensors. Among them, GNSS RTK mainly realizes vehicle attitude measurement and high-precision position acquisition. Inertial navigation devices and other sensors maintain the stability of attitude and high-precision position. The time and distance of their position positioning accuracy and attitude are limited, and GNSSRTK is required to be corrected in real time. However, the implementation of GNSS RTK technology requires the vehicle-mounted equipment to access the ground mobile network in order to obtain the local GNSS correction observation information in the CORS station coverage area, thereby achieving high-precision positioning. In areas where outdoor mobile network signals cannot reach, such as deserts, canyons, and mountains, the navigation terminal relies solely on receiving GNSS signals to achieve centimeter-level high-precision positioning in a short time. This is a difficult problem faced by autonomous driving coverage area capabilities. It takes up to 20 minutes to converge to centimeter-level accuracy through industry-implemented PPP precise single-point positioning, and once the signal is interrupted, it takes a long time to converge again. Summary of the invention

[0003] The technical problem to be solved by the present invention is that in areas where mobile network signals cannot reach, the navigation terminal cannot achieve centimeter-level high-precision positioning in a short time by simply receiving GNSS signals. The purpose is to provide an automatic driving navigation and positioning system and method based on low-orbit satellite communication and navigation integration, and proposes to rely on low-orbit satellites and ground systems, through the navigation payload and communication payload carried by the satellite, to achieve high-precision positioning of automatic driving vehicles in areas where mobile signals cannot reach.

[0004] The present invention is achieved through the following technical solutions:

[0005] The first aspect of the present invention provides an automatic driving navigation and positioning system based on low-orbit satellite communication and navigation integration, characterized in that it includes a ground part, a space part and a vehicle-mounted communication and navigation integration terminal:

[0006] The ground segment is used to monitor satellite data, generate navigation messages and GNSS complete augmentation information using the monitoring data, and upload them to the space segment as required;

[0007] The space segment is used to receive navigation messages uploaded by the ground segment, modulate and generate low-orbit satellite and GNSS navigation signals, and broadcast navigation signals to the vehicle-mounted integrated communication and navigation terminal. At the same time, the low-orbit satellite in the space segment forwards the position information from the vehicle-mounted integrated communication and navigation terminal and the GNSS complete enhancement information of the ground segment;

[0008] The vehicle-mounted integrated communication and navigation terminal is used to receive GNSS navigation signals, obtain the coarse-precision position of the terminal, and send the position to the low-orbit satellite in the space part. The vehicle-mounted integrated communication and navigation terminal is also used to receive low-orbit satellite navigation signals, demodulate in real time to obtain telegram information and low-orbit satellite observation quantities, and combine the GNSS navigation signals and the GNSS complete enhancement information obtained by the communication link to calculate high-precision terminal position information.

[0009] The present invention monitors satellite data through a ground part, generates navigation messages and GNSS complete enhancement information using the monitoring data, and injects them into a space part according to demand; the space part receives the navigation messages uploaded by the ground part, modulates and generates low-orbit satellites and GNSS navigation signals, and broadcasts the navigation signals to a vehicle-mounted integrated communication and navigation terminal; at the same time, the low-orbit satellite in the space part forwards the position information from the vehicle-mounted integrated communication and navigation terminal and the GNSS complete enhancement information of the ground part; the vehicle-mounted integrated communication and navigation terminal receives the GNSS navigation signal, obtains the coarse-precision position of the terminal, and sends the position to the low-orbit satellite in the space part; the vehicle-mounted integrated communication and navigation terminal simultaneously receives the low-orbit satellite navigation signal, demodulates in real time to obtain message information and low-orbit satellite observation quantity, combines the GNSS navigation signal and the GNSS complete enhancement information obtained by the communication link, calculates and obtains high-precision terminal position information, and realizes high-precision positioning of the autonomous driving vehicle in an area where the mobile signal cannot reach, based on the real-time reception of the low-orbit satellite, relying on the low-orbit satellite and the ground system, and through the navigation payload and communication payload carried by the satellite.

[0010] As a further limitation of the present invention, the space segment includes GNSS satellites and low-orbit satellites;

[0011] The ground segment includes ground-based monitoring stations, navigation augmentation data processing centers, gateway stations, and external IGS service networks:

[0012] The ground-based monitoring station is used to monitor satellite data, and the navigation enhancement data processing center is used to receive the monitoring data of the ground-based monitoring station and the IGS service network to generate navigation messages and GNSS complete enhancement information, and to send the navigation messages to the low-orbit satellite through the gateway station. At the same time, the navigation enhancement data processing center forwards the GNSS complete enhancement information to the vehicle-mounted communication and navigation integrated terminal through the low-orbit satellite communication link according to the location of the vehicle-mounted communication and navigation integrated terminal.

[0013] As a further limitation of the present invention, the vehicle-mounted integrated communication and navigation terminal includes a low-orbit satellite communication processing module, a GNSS signal processing module, a low-orbit satellite navigation signal processing module and a processor:

[0014] The low-orbit satellite communication processing module is used to send the initial position information obtained by the GNSS signal processing module to the ground-based navigation enhancement data processing center via the low-orbit satellite, and at the same time receive the navigation enhancement information sent from the navigation enhancement data center via the low-orbit satellite, and send the enhancement information to the processor;

[0015] The GNSS signal processing module is used to receive and process GNSS multi-frequency navigation signals, and send the observed values ​​and navigation message information obtained after processing to the processor;

[0016] The low-orbit satellite navigation signal processing module is used to receive and process the navigation signal broadcast by the low-orbit satellite navigation payload, and send the observed values ​​and navigation message information obtained after processing to the processor;

[0017] The processor is used to receive navigation enhancement information transmitted from the low-orbit satellite communication processing module, observation quantities transmitted from the GNSS signal processing module and the low-orbit satellite navigation signal processing module, complete positioning calculations, select a positioning result to send to the low-orbit satellite communication processing module, and output the positioning result at the same time.

[0018] A second aspect of the present invention provides a low-orbit satellite-based integrated automatic driving navigation and positioning method. Based on the above-mentioned low-orbit satellite-based integrated automatic driving navigation and positioning system, the positioning method includes:

[0019] Determine the number of visible low-orbit satellites:

[0020] When the number of visible low-orbit satellites is not less than four:

[0021] Obtain low-orbit satellite navigation signals and GNSS signals to achieve fast PPP precise single-point real-time positioning;

[0022] When the number of visible low-orbit satellites is less than four:

[0023] Through the low-orbit satellite communication link, the correction and enhancement information of the ground local / wide-area enhanced CORS station is obtained to achieve fast PPPRTK precise single-point real-time positioning.

[0024] As a further limitation of the present invention, the implementation of fast PPP precise single-point real-time positioning includes:

[0025] Obtain the positioning of the onboard GNSS receiver and calibrate the clock of the low-orbit satellite navigation payload through the positioned GNSS receiver;

[0026] Obtain the message data, orbit and clock correction product data corresponding to the onboard GNSS observation data from the IGS service network, and calculate the precise satellite orbit of the low-orbit satellite;

[0027] Acquire monitoring data of low-orbit satellites and process them to obtain real-time precise orbit and satellite clock corrections;

[0028] Integrate low-orbit satellite navigation messages and GNSS enhancement messages based on GNSS enhancement information, real-time precise orbit and satellite clock correction data;

[0029] The message is spread spectrum modulated to the designed frequency through the low-orbit satellite and then the navigation signal is broadcasted through the satellite antenna in sequence;

[0030] The ground-mounted integrated communication and navigation terminal receives navigation signals and GNSS signals from low-orbit satellites.

[0031] As a further limitation of the present invention, the ground vehicle-mounted integrated communication and navigation terminal receives low-orbit satellite navigation signals and GNSS signals for data processing, and the data processing includes:

[0032] Amplification, frequency conversion, filtering, AD conversion output to baseband processing, baseband processing completes signal capture, tracking, synchronization, demodulation and decoding;

[0033] Obtain low-orbit satellite observations, GNSS satellite observations, low-orbit satellite navigation messages, GNSS navigation messages and GNSS enhancement messages;

[0034] PPP precise point positioning solution is performed based on the acquired information.

[0035] As a further limitation of the present invention, the fast PPPRTK precise single point real-time positioning specifically includes:

[0036] Obtain the location information of the vehicle-mounted communication and navigation integrated terminal;

[0037] Calculate the GNSS complete augmentation information including atmospheric correction numbers in the area where the vehicle-mounted integrated communication and navigation terminal is located;

[0038] Through the low-orbit satellite communication link, the vehicle-mounted integrated communication and navigation terminal obtains complete local GNSS enhancement information;

[0039] According to low-orbit satellite observations and navigation messages, GNSS observations and navigation messages, and GNSS complete enhancement information, a non-differential non-combined PPP positioning solution model is established;

[0040] Calculate the high-precision position of the vehicle-mounted integrated communication and navigation terminal.

[0041] As a further limitation of the present invention, the GNSS complete enhanced correction information including the atmospheric correction number is sent to the vehicle-mounted integrated communication and navigation terminal communication processing module through the low-orbit satellite signal gateway and the inter-satellite communication link, and the correction information data is transmitted to the navigation positioning solution processor. When the navigation enhancement data center uploads the correction information, the clock correction parameters are transmitted in the form of high sampling data.

[0042] As a further limitation of the present invention, the non-difference non-combined PPP positioning solution model selects the system and frequency number according to the completeness of GNSS signal reception and enhancement information, and performs PPPRTK precise single-point positioning solution model positioning solution in combination with correction information to complete terminal position and various error estimates. The correction information includes atmospheric correction number, precise orbit, precise clock difference and phase fractional deviation FCB.

[0043] As a further limitation of the present invention, the positioning solution process includes data preparation, establishing an observation model, data preprocessing, parameter estimation and ambiguity fixing:

[0044] The data preparation includes utilizing the acquired visible satellite pseudo-range observations and low-orbit satellites, GNSS navigation messages, constructing equations and least squares / Kalman filter algorithms to achieve single-point positioning;

[0045] The establishment of the observation model includes taking pseudorange and carrier phase observation as the basis, and different observation models can be selected according to the ionospheric delay processing requirements;

[0046] The preprocessing includes monitoring and eliminating the acquired low-orbit satellite pseudo-range gross errors, detecting and repairing the receiver clock jump, and detecting the carrier phase cycle jump;

[0047] The parameter estimation includes performing parameter estimation based on the established observation model by using methods such as inertial adjustment method or Kalman filtering to obtain parameters such as terminal position, clock error, carrier phase difference and phase correction number;

[0048] The ambiguity fixation includes fixing the integer ambiguity of the carrier phase using a combination of wide terms and narrow terms, and determining whether a floating point solution or a fixed solution is performed based on whether wide and narrow lane phase decimal deviation correction numbers are received.

[0049] Compared with the prior art, the present invention has the following advantages and beneficial effects:

[0050] 1. It can switch and integrate PPP positioning and PPPRTK positioning in areas where mobile network signals cannot reach, such as deserts, canyons, and mountains, based on the real-time reception of low-orbit satellites;

[0051] 2. Establish ionosphere-free combined model and non-difference non-combined model, which can meet the real number solution application and fixed solution real-time high-precision requirements;

[0052] 3. The Navigation Augmentation Data Center predicts satellite orbits and coverage areas, and can broadcast enhanced correction information in real time for areas covered by satellite communication beams.

[0053] 4. The orbital height of low-orbit satellites is lower than that of GNSS satellites. The same broadcast power is attenuated through the path, and the power reaching the ground is stronger, which can better adapt to the positioning performance of vehicle-mounted integrated communication and navigation terminals in obstructed and multipath environments. BRIEF DESCRIPTION OF THE DRAWINGS

[0054] In order to more clearly illustrate the technical solutions of the exemplary embodiments of the present invention, the following briefly introduces the drawings required for use in the embodiments. It should be understood that the following drawings only illustrate certain embodiments of the present invention and should not be regarded as limiting the scope. For those of ordinary skill in the art, other relevant drawings can be obtained based on these drawings without creative work. In the drawings:

[0055] Figure 1 Schematic diagram of the structure of the vehicle-mounted integrated communication and navigation terminal in an embodiment of the present invention;

[0056] Figure 2 A flowchart for realizing fast and high-precision positioning of the vehicle-mounted integrated communication and navigation terminal in an embodiment of the present invention;

[0057] Figure 3 These are two methods for realizing fast and high-precision positioning of the vehicle-mounted integrated communication and navigation terminal in the embodiments of the present invention. DETAILED DESCRIPTION

[0058] In order to make the objectives, technical solutions and advantages of the present invention more clearly understood, the present invention is further described in detail below in conjunction with embodiments and drawings. The exemplary embodiments of the present invention and their description are only used to explain the present invention and are not intended to limit the present invention.

[0059] Example 1

[0060] like Figure 1 As shown,

[0061] The first aspect of this embodiment provides an automatic driving navigation and positioning system based on low-orbit satellite communication and navigation integration, including a ground part, a space part and a vehicle-mounted communication and navigation integration terminal:

[0062] The ground segment is used to monitor satellite data, generate navigation messages and GNSS complete augmentation information using the monitoring data, and upload them to the space segment as needed;

[0063] The space segment is used to receive navigation messages uploaded by the ground segment, modulate and generate low-orbit satellite and GNSS navigation signals, and broadcast navigation signals to the vehicle-mounted integrated communication and navigation terminal. At the same time, the low-orbit satellite in the space segment forwards the position information from the vehicle-mounted integrated communication and navigation terminal and the GNSS complete enhancement information of the ground segment;

[0064] The vehicle-mounted integrated communication and navigation terminal is used to receive GNSS navigation signals, obtain the coarse-precision position of the terminal, and send the position to the low-orbit satellite in the space part. The vehicle-mounted integrated communication and navigation terminal is also used to receive low-orbit satellite navigation signals, demodulate in real time to obtain telegram information and low-orbit satellite observation quantities, and combine the GNSS navigation signals and the GNSS complete enhancement information obtained through the communication link to calculate the high-precision terminal position information.

[0065] The present invention monitors satellite data through a ground part, generates navigation messages and GNSS complete enhancement information using the monitoring data, and injects them into a space part according to demand; the space part receives the navigation messages uploaded by the ground part, modulates and generates low-orbit satellites and GNSS navigation signals, and broadcasts the navigation signals to a vehicle-mounted integrated communication and navigation terminal; at the same time, the low-orbit satellite in the space part forwards the position information from the vehicle-mounted integrated communication and navigation terminal and the GNSS complete enhancement information of the ground part; the vehicle-mounted integrated communication and navigation terminal receives the GNSS navigation signal, obtains the coarse-precision position of the terminal, and sends the position to the low-orbit satellite in the space part; the vehicle-mounted integrated communication and navigation terminal simultaneously receives the low-orbit satellite navigation signal, demodulates in real time to obtain message information and low-orbit satellite observation quantity, combines the GNSS navigation signal and the GNSS complete enhancement information obtained by the communication link, calculates and obtains high-precision terminal position information, and realizes high-precision positioning of the autonomous driving vehicle in an area where the mobile signal cannot reach, based on the real-time reception of the low-orbit satellite, relying on the low-orbit satellite and the ground system, and through the navigation payload and communication payload carried by the satellite.

[0066] In some possible embodiments, the low-orbit satellite communication processing module is used to send the initial position information obtained by the GNSS signal processing module to the ground data processing center via the low-orbit satellite, and at the same time receive the navigation enhancement information sent to itself from the data center via the low-orbit satellite, and send the enhancement information to the processor; the GNSS signal processing module is used to receive and process the GNSS multi-frequency navigation signal, and send the observation amount and navigation message information obtained after processing to the processor; the low-orbit satellite navigation signal processing module is used to receive and process the navigation signal broadcast by the low-orbit satellite navigation payload, and send the observation amount and navigation message information obtained after processing to the processor; the processor is used to receive the navigation enhancement information transmitted from the low-orbit satellite communication processing module, the observation amount transmitted from the GNSS signal processing module and the low-orbit satellite navigation signal processing module, complete the positioning calculation, and select a positioning result to send to the low-orbit satellite communication processing module, and output the positioning result at the same time. The transmission channel from the low-orbit satellite to the navigation enhancement data center is the dedicated communication link from the low-orbit satellite inter-satellite communication link and the satellite data downlink to the gateway station, from the low-orbit satellite to the gateway station and then to the navigation enhancement data center.

[0067] In some possible embodiments, the space segment includes GNSS satellites and low-orbit satellites;

[0068] The ground segment includes ground-based monitoring stations, navigation augmentation data processing centers, gateway stations, and external IGS service networks:

[0069] The ground-based monitoring station is used to monitor satellite data, and the navigation augmentation data processing center is used to receive the monitoring data of the ground-based monitoring station and the IGS service network to generate navigation messages and GNSS complete augmentation information, and to send the navigation messages to the low-orbit satellite through the gateway station. At the same time, the navigation augmentation data processing center forwards the GNSS complete augmentation information to the vehicle-mounted communication and navigation integrated terminal through the low-orbit satellite communication link according to the location of the vehicle-mounted communication and navigation integrated terminal.

[0070] In some possible embodiments, the vehicle-mounted integrated communication and navigation terminal includes a low-orbit satellite communication processing module, a GNSS signal processing module, a low-orbit satellite navigation signal processing module and a processor:

[0071] The low-orbit satellite communication processing module is used to send the initial position information obtained by the GNSS signal processing module to the ground-based navigation enhancement data processing center via the low-orbit satellite, and at the same time receive the navigation enhancement information sent from the navigation enhancement data center via the low-orbit satellite, and send the enhancement information to the processor;

[0072] The GNSS signal processing module is used to receive and process GNSS multi-frequency navigation signals, and send the obtained observation quantities and navigation message information after processing to the processor;

[0073] The low-orbit satellite navigation signal processing module is used to receive and process the navigation signal broadcast by the low-orbit satellite navigation payload, and send the observed values ​​and navigation message information obtained after processing to the processor;

[0074] The processor is used to receive the navigation enhancement information transmitted by the low-orbit satellite communication processing module, the observation values ​​transmitted by the GNSS signal processing module and the low-orbit satellite navigation signal processing module, complete the positioning calculation, select a positioning result to send to the low-orbit satellite communication processing module, and output the positioning result at the same time.

[0075] like Figure 2 and Figure 3 As shown,

[0076] A second aspect of this embodiment provides a low-orbit satellite-based integrated automatic driving navigation and positioning method. Based on the above-mentioned low-orbit satellite-based integrated automatic driving navigation and positioning system, the positioning method includes:

[0077] Determine the number of visible low-orbit satellites:

[0078] When the number of visible low-orbit satellites is not less than four:

[0079] Obtain low-orbit satellite navigation signals and GNSS signals to achieve fast PPP precise single-point real-time positioning;

[0080] When the number of visible low-orbit satellites is less than four:

[0081] Through the low-orbit satellite communication link, the correction and enhancement information of the ground local / wide-area enhanced CORS station is obtained to achieve fast PPPRTK precise single-point real-time positioning.

[0082] In some possible embodiments, implementing fast PPP precise single point real-time positioning includes:

[0083] The low-orbit satellite is equipped with a GNSS receiver to receive GNSS signals and achieve positioning. The 1PPS of the positioned GNSS receiver is used to calibrate the low-orbit satellite navigation payload clock, so that the low-orbit satellite navigation time system is synchronized with the GNSS.

[0084] At the same time, the transmission of GNSS observation data from low-orbit satellites to the gateway station and then to the navigation augmentation data center is completed by using the inter-satellite communication link of low-orbit satellites and the dedicated communication link for satellite data downlink to the gateway station;

[0085] The Navigation Augmentation Data Center obtains the onboard GNSS observation data transmitted by the low-orbit satellite, and combines it with the precise GNSS ephemeris and clock product data obtained from the IGS. It obtains the position of the low-orbit satellite through PPP post-processing technology, and obtains the satellite orbit by combining orbital dynamics fitting and correction.

[0086] Acquire monitoring data of low-orbit satellites from multiple ground-based monitoring stations on the ground of low-orbit satellites, and process them to obtain real-time precise orbit correction and satellite clock correction;

[0087] The Navigation Augmentation Data Center integrates the low-orbit satellite navigation message and GNSS augmentation message based on the real-time GNSS augmentation information and low-orbit satellite precise orbit and clock correction information obtained from the IGS.

[0088] The Navigation Augmentation Data Center sends the compiled low-orbit satellite navigation message and GNSS augmentation message to the gateway station, which then sends it to the low-orbit satellite through the feeder link. The low-orbit satellite spread-spectrum modulates the message to the designed frequency point and then broadcasts the navigation signal through the satellite antenna sequence.

[0089] The ground-mounted vehicle-mounted integrated communication and navigation terminal receives low-orbit satellite navigation signals and GNSS signals;

[0090] The signal is received and amplified by the antenna, and down-converted, filtered and AD converted in the RF processing and output to the baseband processing. The baseband processing completes the signal capture, tracking, synchronization, demodulation and decoding, and obtains low-orbit satellite observations, GNSS satellite observations, low-orbit satellite navigation messages, GNSS navigation messages, and GNSS enhancement messages. This information is used to perform PPP precise single-point positioning solution.

[0091] In some possible embodiments, fast PPPRTK precise single point real-time positioning specifically includes:

[0092] The vehicle-mounted integrated communication and navigation terminal obtains the basic location information of the vehicle, sends the location information to the low-orbit satellite through the communication link of the low-orbit satellite, transmits the data to the ground signal gateway station through the inter-satellite link, and then transmits it to the navigation enhancement data processing center;

[0093] Based on the vehicle position, the navigation augmentation data processing center relies on nearby low-orbit satellite ground-based monitoring stations and local / wide-area GNSS ground-based monitoring stations or IGMASS stations to obtain the atmospheric correction parameters of the vehicle area through station-by-station calculation and refined solution, and simultaneously calculates the low-orbit satellite precise orbit correction, precise clock correction and phase decimal deviation;

[0094] The navigation augmentation data processing center also obtains global GNSS correction information from IGS. The global GNSS correction information includes precise orbit correction, precise clock correction and phase decimal deviation.

[0095] Combine low-orbit satellite and GNSS precise orbit, precise clock error, phase decimal deviation, atmospheric delay parameter and other correction information. In the navigation augmentation data processing center, the constellation satellite orbit prediction model is used to switch and broadcast the correction information of the beam coverage area during the transit in real time for the ground coverage area;

[0096] The Navigation Augmentation Data Center sends the edited correction information to the vehicle-mounted integrated communication terminal communication processing module through the low-orbit satellite signal gateway and inter-satellite communication link, and transmits the correction information data to the navigation positioning solution processor. When the Navigation Augmentation Data Center uploads the correction information, the clock correction parameters are transmitted as high-sampling data as possible, thereby improving the positioning accuracy and ambiguity fixation time;

[0097] The vehicle-mounted integrated communication and navigation terminal uses the enhanced correction information obtained from the communication processing module, combined with the GNSS observations and navigation messages output by its own GNSS signal processing module, to establish a non-differential non-combined PPP positioning solution model in the positioning solution processor;

[0098] In the positioning solution model, the system and frequency number can be selected according to the completeness of GNSS signal reception and enhancement information. Combined with the correction information (precision orbit, precision clock error, phase fractional deviation FCB, atmospheric correction number), according to the above-mentioned PPP data preparation, observation model establishment, data preprocessing, parameter estimation, ambiguity fixation and other processes, the terminal position and various error estimates are completed.

[0099] In some possible embodiments, the positioning solution process includes data preparation, establishing an observation model, data preprocessing, parameter estimation, and ambiguity fixation:

[0100] Data preparation includes using the acquired visible satellite pseudo-range observations and low-orbit satellites, GNSS navigation messages, and achieving single-point positioning through equation building and least squares / Kalman filter algorithms;

[0101] Establish observation models and perform parameter estimation based on pseudorange and carrier phase observations. Different observation models can be selected according to the ionospheric delay processing requirements. Combination elimination and parameter estimation methods can be used. For example, the combination elimination method includes a dual-frequency ionosphere-free linear combination model with real solutions and a UOFC model to reduce observation noise. The parameter estimation method includes a non-difference non-combination model, etc.

[0102] Preprocessing includes monitoring and eliminating the gross errors of the visible satellite pseudoranges of each system, detecting and repairing the receiver clock jumps, and detecting carrier phase cycle slips. For small cycle slips and gross errors that cannot be accurately detected and identified in the preprocessing stage, the post-test residuals of the observation values ​​can be used for comprehensive analysis after parameter estimation. Since the reliability of cycle slip repair is difficult to guarantee, and incorrect repair is not conducive to parameter estimation, repair is generally not performed;

[0103] Parameter estimation includes performing parameter estimation based on the established observation model through methods such as inertial adjustment or Kalman filtering to obtain parameters such as terminal position, clock error, carrier phase difference and phase correction number;

[0104] Ambiguity fixation includes using a combination of wide and narrow terms to fix the integer ambiguity of the carrier phase. Depending on whether the wide and narrow lane phase decimal deviation correction numbers sent by the enhancement data center are received, the floating point solution and the fixed solution are determined and the solution result is output.

[0105] Example 2

[0106] The PPP solution process is listed below. The PPPRTK algorithm is consistent with the main PPP solution process.

[0107] (1) Establishing the observation model

[0108] Using carrier phase observation and pseudorange observations The model without combined observations is established:

[0109]

[0110]

[0111] The low-order terms of ionospheric delay are eliminated by dual-frequency linear combination. When using precise orbit and clock errors, satellite orbit errors and satellite clock errors are ignored. Code delay can be absorbed by clock errors, and initial phase and phase delay can be absorbed by ambiguity. and They represent the carrier phase observation and pseudorange observation of the ionosphere-free combination respectively, and their model forms are as follows:

[0112]

[0113]

[0114] Among them, the linear combination coefficient f i and f j are the two frequency values ​​of the signal, is the geometric distance between the position of the satellite s at the time of signal transmission and the position of the receiver r at the time of signal reception, c is the speed of light, dt r (t r ) is the receiver clock error, dT s (t s ) is the satellite clock error, is the layer delay, Ionosphere-free model carrier phase difference (including integer ambiguity); φ r，0，LC is the initial carrier phase cycle of the ionospheric linear combination signal at the local receiver reception time; The initial carrier phase cycle of the ionosphere-free linear combination signal at the time of satellite launch; Carrier phase difference integer ambiguity of the ionosphere-free linear combination signal.

[0115] Ionosphere-free linear combination signal carrier phase correction number:

[0116]

[0117] The unit vector from the receiver r to the satellite s corresponds to the azimuth; The unit vector from the receiver r to the satellite s corresponds to the elevation angle; d r，pco，i and The antenna phase center offset (PCO) between the receiver and the satellite; d r，pcv，i (El) and Receiver and satellite antenna phase center variation (PCV); d r，disp，i is the site displacement caused by external reasons; φ pw : Phase wrapping error;

[0118] Other modelable errors, such as the phase center deviation and variation (PCV) between the satellite and the receiver antenna, solid tide, ocean tide, phase winding, etc., can be eliminated through the model. Some errors that are difficult to accurately model, such as the wet component of tropospheric delay, are solved by parameter estimation.

[0119] (2) Pretreatment

[0120] Preprocessing includes pseudo-range gross error detection and elimination, clock error detection and repair, and phase cycle jump detection. Among them, pseudo-code gross error detection can use the pseudo-range observation difference method to perform threshold judgment to distinguish whether a pseudo-range jump occurs; the impact of terminal clock drift on pseudo-range / carrier step phenomenon is repaired accordingly, which will not be introduced in detail here. The method of carrier phase cycle jump detection can be carried out in the following ways:

[0121] Ignoring satellite and receiver hardware delays, the single-frequency ionospheric delay at epoch t is calculated as:

[0122]

[0123] Among them, λ1 and λ2 are the wavelengths of the two frequency points; f1 and f2 are the corresponding frequencies; N1 and N2 are the corresponding integer ambiguities; are the carrier phase observation values ​​corresponding to epoch t (in weeks). Using the difference between adjacent epochs, the ionospheric delay variation (IONDV) is:

[0124]

[0125] The error of three times the ionospheric delay variation is taken as the decision threshold, that is, |Dc (t)|≥3σ IONDV When , it is considered that a cycle slip has occurred in this epoch. The observation data with confirmed cycle slips are removed in real time.

[0126] (3) Parameter estimation

[0127] There are many unknowns that need to be solved, and the extended Kalman filter method is used for estimation and solution.

[0128] The Kalman filter model is established as follows:

[0129] x k =F k，k-1 x k-1 +w (8)

[0130] y k =H k x k +v (9)

[0131] where x k ,y k represents the state vector at time t(k), ω and v represent system noise and observation noise, F k，k-1 represents the state transition matrix from time k-1 to time k, H k Represents the observation equation coefficient matrix at time K.

[0132] The various matrices / vectors are as follows:

[0133] A. State Vector

[0134] The state quantity to be estimated mainly includes three aspects:

[0135] a. PVT information of the receiver;

[0136] b. Errors that are difficult to accurately model, generally divided into zenith total delay and tropospheric delay;

[0137] c.Carrier phase deviation.

[0138] Combining the above three aspects of state quantities, the state vector expression to be estimated is obtained as follows:

[0139]

[0140] In the formula represents the receiver position, represents the receiver speed, c represents the speed of light, dt r represents the receiver clock error, Z r Zenith total delay, G N，r and G E，r Tropospheric grid northing delay and easting delay, B LCIndicates the ionosphere-free model carrier phase deviation

[0141]

[0142] B. Observation Vector

[0143] The observation vector consists of two parts: the carrier phase observation of the ionosphere-free linear combination and the pseudorange observation:

[0144]

[0145] Φ LC Represents the dual-frequency ionospheric-free linear combination carrier phase observation:

[0146]

[0147] P LC Represents the dual-frequency ionosphere-free linear combination pseudorange observation:

[0148]

[0149] C. State transfer matrix

[0150]

[0151] D. Observation Matrix

[0152]

[0153] in

[0154]

[0155] parameter represents the unit direction vector from the receiver r to the satellite s,

[0156]

[0157] E. Identity Matrix

[0158]

[0159]

[0160] in, Tropospheric error grid map function; The unit vector from the receiver r to the satellite s corresponds to the elevation angle; The unit vector from the receiver r to the satellite s corresponds to the azimuth;

[0161] a. Measurement noise vector covariance matrix:

[0162]

[0163] in,

[0164]

[0165] in, Represents the standard deviation of the L1 carrier phase observation error

[0166]

[0167] in, Represents the standard deviation of the L1 pseudorange observation error

[0168] b. System noise covariance matrix:

[0169] Q=C0v(w) (22)

[0170] c. Start Kalman filter step parameter estimation

[0171] d. Status prediction:

[0172]

[0173] e. Filter gain:

[0174]

[0175] f. State estimation:

[0176]

[0177] g. Prediction variance matrix:

[0178]

[0179] h. Estimated variance matrix:

[0180] P k =(IK k H k ) k，k-1 (27)

[0181] From the above steps, we only need to set the initial state value x0 and its variance matrix P0. After continuous prediction and correction, we can output the terminal position, real ambiguity, and estimation error solution results.

[0182] (4) Fuzziness Fixation

[0183] According to the original pseudorange and carrier phase observation data, the LAMBDA algorithm is used to fix the integer ambiguity;

[0184] Using the least squares algorithm to find the floating point solution of the ambiguity and the corresponding covariance matrix

[0185] Solve with integer number N and floating point The square of the distance between is the objective function, and the integer ambiguity N is searched to minimize the objective function. As shown in the following formula:

[0186]

[0187] In the formula for The diagonal matrix of the covariance matrix, in order to reduce the correlation between ambiguities, performs an integer transformation (Z transformation) during the search, turning the original search for N in a narrow ellipsoid into a search for M in an approximate spherical space:

[0188]

[0189] In this way, the search for the optimal integer solution of M is completed, and then the optimal integer ambiguity solution N is obtained;

[0190] The fixed integer ambiguity and the decimal part are combined and substituted into the terminal position.

[0191] The above specific implementation methods further illustrate the objectives, technical solutions and beneficial effects of the present invention in detail. It should be understood that the above are only specific implementation methods of the present invention and are not intended to limit the scope of protection of the present invention. Any modifications, equivalent substitutions, improvements, etc. made within the spirit and principles of the present invention should be included in the scope of protection of the present invention.

Claims

1. An automatic driving navigation and positioning system based on low-orbit satellite communication and navigation, characterized in that: It includes the ground part, the space part and the vehicle-mounted integrated communication and navigation terminal: The ground segment is used to monitor satellite data, generate navigation messages and GNSS complete augmentation information using the monitoring data, and upload them to the space segment as required; The space segment is used to receive navigation messages uploaded by the ground segment, modulate and generate low-orbit satellite and GNSS navigation signals, and broadcast navigation signals to the vehicle-mounted integrated communication and navigation terminal. At the same time, the low-orbit satellite in the space segment forwards the position information from the vehicle-mounted integrated communication and navigation terminal and the GNSS complete enhancement information of the ground segment; The vehicle-mounted communication and navigation integrated terminal is used to receive GNSS navigation signals, obtain the coarse-precision position of the terminal, and send the position to the low-orbit satellite in the space part. The vehicle-mounted communication and navigation integrated terminal is also used to receive low-orbit satellite navigation signals, demodulate in real time to obtain telegram information and low-orbit satellite observations, and combine the GNSS navigation signals and the GNSS complete enhancement information obtained by the communication link to calculate the high-precision terminal position information; The vehicle-mounted integrated communication and navigation terminal includes a low-orbit satellite communication processing module, a GNSS signal processing module, a low-orbit satellite navigation signal processing module and a processor: The low-orbit satellite communication processing module is used to send the initial position information obtained by the GNSS signal processing module to the ground-based navigation enhancement data processing center via the low-orbit satellite, and at the same time receive the navigation enhancement information sent from the navigation enhancement data center via the low-orbit satellite, and send the enhancement information to the processor; The GNSS signal processing module is used to receive and process GNSS multi-frequency navigation signals, and send the observed values ​​and navigation message information obtained after processing to the processor; The low-orbit satellite navigation signal processing module is used to receive and process the navigation signal broadcast by the low-orbit satellite navigation payload, and send the observed values ​​and navigation message information obtained after processing to the processor; The processor is used to receive navigation enhancement information transmitted from the low-orbit satellite communication processing module, observation quantities transmitted from the GNSS signal processing module and the low-orbit satellite navigation signal processing module, complete positioning calculations, select a positioning result to send to the low-orbit satellite communication processing module, and output the positioning result at the same time.

2. The low-orbit satellite-based integrated automatic driving navigation and positioning system according to claim 1 is characterized in that: The space segment includes GNSS satellites and low-orbit satellites; The ground segment includes ground-based monitoring stations, navigation augmentation data processing centers, gateway stations, and external IGS service networks: The ground-based monitoring station is used to monitor satellite data, and the navigation enhancement data processing center is used to receive the monitoring data of the ground-based monitoring station and the IGS service network to generate navigation messages and GNSS complete enhancement information, and to send the navigation messages to the low-orbit satellite through the gateway station. At the same time, the navigation enhancement data processing center forwards the GNSS complete enhancement information to the vehicle-mounted communication and navigation integrated terminal through the low-orbit satellite communication link according to the location of the vehicle-mounted communication and navigation integrated terminal.

3. A low-orbit satellite navigation and positioning integrated automatic driving navigation method, characterized in that: Based on the low-orbit satellite integrated automatic driving navigation and positioning system according to any one of claims 1-2, the positioning method includes: Determine the number of visible low-orbit satellites: When the number of visible low-orbit satellites is not less than four: Obtain low-orbit satellite navigation signals and GNSS signals to achieve fast PPP precise single-point real-time positioning; When the number of visible low-orbit satellites is less than four: Through the low-orbit satellite communication link, the correction and enhancement information of the ground local / wide-area enhanced CORS station is obtained to achieve fast PPPRTK precise single-point real-time positioning.

4. The method for automatic driving navigation and positioning based on low-orbit satellite communication and navigation integration according to claim 3 is characterized in that: The implementation of fast PPP precise single-point real-time positioning includes: Obtain the positioning of the onboard GNSS receiver and calibrate the clock of the low-orbit satellite navigation payload through the positioned GNSS receiver; Obtain the message data, orbit and clock correction product data corresponding to the onboard GNSS observation data from the IGS service network, and calculate the precise satellite orbit of the low-orbit satellite; Acquire monitoring data of low-orbit satellites and process them to obtain real-time precise orbit and satellite clock corrections; Integrate low-orbit satellite navigation messages and GNSS enhancement messages based on GNSS enhancement information, real-time precise orbit and satellite clock correction data; The message is spread spectrum modulated to the designed frequency through the low-orbit satellite and then the navigation signal is broadcasted through the satellite antenna in sequence; The ground-mounted integrated communication and navigation terminal receives navigation signals and GNSS signals from low-orbit satellites.

5. The method for automatic driving navigation and positioning based on low-orbit satellite communication and navigation integration according to claim 4 is characterized in that: The ground vehicle-mounted integrated communication and navigation terminal receives low-orbit satellite navigation signals and GNSS signals for data processing, and the data processing includes: Amplification, frequency conversion, filtering, AD conversion output to baseband processing, baseband processing completes signal capture, tracking, synchronization, demodulation and decoding; Obtain low-orbit satellite observations, GNSS satellite observations, low-orbit satellite navigation messages, GNSS navigation messages and GNSS enhancement messages; PPP precise point positioning solution is performed based on the acquired information.

6. The method for automatic driving navigation and positioning based on low-orbit satellite communication and navigation integration according to claim 3 is characterized in that: The fast PPPRTK precise single-point real-time positioning specifically includes: Obtain the location information of the vehicle-mounted communication and navigation integrated terminal; Calculate the GNSS complete augmentation information including atmospheric correction numbers in the area where the vehicle-mounted integrated communication and navigation terminal is located; Through the low-orbit satellite communication link, the vehicle-mounted integrated communication and navigation terminal obtains complete local GNSS enhancement information; According to low-orbit satellite observations and navigation messages, GNSS observations and navigation messages, and GNSS complete enhancement information, a non-differential non-combined PPP positioning solution model is established; Calculate the high-precision position of the vehicle-mounted integrated communication and navigation terminal.

7. The method for automatic driving navigation and positioning based on low-orbit satellite communication and navigation integration according to claim 6 is characterized in that: The GNSS complete enhanced correction information including the atmospheric correction number is sent to the vehicle-mounted integrated communication and navigation terminal communication processing module through the low-orbit satellite gateway and the inter-satellite communication link, and the correction information data is transmitted to the navigation positioning solution processor. When the navigation enhancement data center uploads the correction information, the clock correction parameters are transmitted in the form of high sampling data.

8. The method for automatic driving navigation and positioning based on low-orbit satellite communication and navigation integration according to claim 6 is characterized in that: The non-difference non-combined PPP positioning solution model selects the system and frequency number according to the completeness of GNSS signal reception and enhancement information, and performs positioning solution of the PPPRTK precise single-point positioning solution model in combination with correction information to complete the terminal position and various error estimates. The correction information includes atmospheric correction numbers, precise orbits, precise clock errors and phase fractional deviations FCB.

9. The method for automatic driving navigation and positioning based on low-orbit satellite communication and navigation integration according to claim 5 or 6, characterized in that: The positioning solution process includes data preparation, observation model establishment, data preprocessing, parameter estimation and ambiguity fixation: The data preparation includes utilizing the acquired visible satellite pseudo-range observations and low-orbit satellites, GNSS navigation messages, constructing equations and utilizing the least squares / Kalman filter algorithm to achieve single-point positioning; The establishment of the observation model includes taking pseudorange and carrier phase observation as the basis, and different observation models can be selected according to the ionospheric delay processing requirements; The preprocessing includes monitoring and eliminating the acquired low-orbit satellite pseudo-range gross errors, detecting and repairing the receiver clock jump, and detecting the carrier phase cycle jump; The parameter estimation includes performing parameter estimation based on the established observation model by using methods such as inertial adjustment method or Kalman filtering to obtain parameters such as terminal position, clock error, carrier phase difference and phase correction number; The ambiguity fixation includes fixing the integer ambiguity of the carrier phase using a combination of wide terms and narrow terms, and determining whether a floating point solution or a fixed solution is performed based on whether wide and narrow lane phase decimal deviation correction numbers are received.

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