A take-off and landing guidance system based on multi-benchmark dynamic differential positioning

Abstract

The application discloses a take-off and landing guiding system based on multi-reference dynamic differential positioning, which comprises a ground terminal guiding device and an aviation platform guiding device, wherein the ground terminal guiding device is provided with a plurality of ground terminal satellite signal receiving modules, a satellite signal reference station, a integrity monitoring module, a data link and a data link antenna; the satellite signal reference station calculates reference station observation data sets from satellite signals output by the ground terminal satellite signal receiving modules; the integrity monitoring module monitors each group of reference station observation data sets, removes faulty carrier phase observations and pseudo distances in each group of reference station observation data sets, and selects optimal reference station observation data sets to send to the data link; and the data link antenna transmits the data to the aviation platform for take-off and landing guiding calculation. The application can stably provide accurate pseudo distances and carrier phase observations, isolate satellite signal reference station faults, and improve the precision and reliability of relative positioning data.

Description

Technical Field

[0001] This invention relates to the field of communication and navigation, specifically to a takeoff and landing guidance system based on multi-reference dynamic differential positioning, which is applied to the field of high-precision relative positioning in aviation. Background Technology

[0002] Differential satellite takeoff and landing guidance systems applied to aircraft platform takeoff and landing typically use ground satellite navigation devices as reference stations and aircraft platform satellite navigation devices as rover stations to acquire accurate relative positioning information and aircraft platform attitude information. By employing multi-reference redundant data and selecting the reference station observation data of the best quality, the system can still provide accurate observation data even when affected by environmental factors and human interference, thereby improving relative positioning accuracy and enhancing the autonomous takeoff and landing capabilities of aircraft platforms. Summary of the Invention

[0003] To improve the stability and accuracy of takeoff and landing of aircraft platforms and reduce the impact of reference station observation data during takeoff and landing, this invention proposes a takeoff and landing guidance system based on multi-reference dynamic differential positioning. The system selects the reference station observation data of optimal quality based on integrity risk, enabling the rover to obtain the relatively best reference station observation data in harsh environments and providing the most accurate relative positioning solution to the takeoff and landing guidance and control equipment.

[0004] The objective of this invention is achieved through the following technical solution:

[0005] A takeoff and landing guidance system based on multi-reference dynamic differential positioning includes a ground-end guidance device and an aircraft platform guidance device.

[0006] The ground-based guidance device includes several ground-based satellite navigation receiver modules, one satellite navigation reference station, one integrity monitoring module, one data link, and one data link antenna.

[0007] Each ground-based satellite navigation receiver module contains a high-precision satellite antenna and a receiver. The receiver receives satellite signals from the high-precision satellite antenna, and after filtering and amplification, transmits them to the satellite navigation reference station via radio frequency lines.

[0008] The satellite navigation reference station performs radio frequency front-end and baseband signal processing on the satellite signals output by the satellite navigation receiving modules at each ground end, and calculates the reference station observation dataset. The reference station observation dataset includes pseudorange and carrier phase observations provided by each satellite; each set of reference station observation datasets is transmitted to the integrity monitoring module.

[0009] The integrity monitoring module monitors the observation datasets of each set of base stations. Based on the fault judgment strategy, it determines whether the status of each carrier phase observation and pseudorange in each set of base station observation datasets is normal. After removing the faulty carrier phase observations and pseudoranges in each set of base station observation datasets, it selects the main base station observation dataset based on the priority selection strategy and sends the main base station observation dataset to the data link. The main base station observation dataset is then transmitted to the aviation platform through the data link antenna for takeoff and landing guidance calculations.

[0010] Preferably, the fault diagnosis strategy is as follows:

[0011] 1) Carrier accumulation - step size monitoring:

[0012] Define carrier phase correction The calculation method is as follows:

[0013]

[0014] Where m represents the ground-end satellite navigation receiver module number, and n represents the satellite number received by the ground-end satellite navigation receiver module. Let mn be the carrier phase observation given by the satellite at the current time k, and R be the carrier phase observation given by the satellite at the current time k. m,n Let τ be the geometric distance. m,n Correction number for the star clock. This represents the carrier phase correction at the initial moment.

[0015] By averaging and removing the influence of clock bias from the ground-based satellite navigation receiver module, we obtain:

[0016]

[0017] Among them, S m It is the N received by the ground-based satellite navigation receiver module m. m The set of satellites, where j represents the satellite number received by the ground-based satellite navigation receiver module m;

[0018] For carrier observations over several consecutive epochs A second-order least-squares fit is performed on it, and the fitting method is as follows:

[0019]

[0020] Where t represents the time interval elapsed relative to time k;

[0021] Therefore, the coefficients of the slope and acceleration terms at the current moment are:

[0022]

[0023] The step size monitoring value is calculated as the deviation between the observed value at the current time k and the fitting result:

[0024]

[0025] Among them, T s Indicates the sampling period. This represents the prediction result obtained from the fitting formula calculation in the previous epoch;

[0026] If any of the slope, acceleration, and step size exceeds the threshold, an alarm flag is set at the corresponding ground-end satellite navigation receiver module to exclude the carrier phase observations of the corresponding satellite obtained from that ground-end satellite navigation receiver module.

[0027] 2) Carrier smoothing code phase measurement update monitoring:

[0028] The statistical measure for updating monitoring is defined as follows:

[0029]

[0030] Where ρ represents the pseudo-distance, ρ s,m,n Carrier smoothing code phase measurement, ρ s,m,n The calculation method is as follows:

[0031]

[0032] in,

[0033] The update monitoring judgment strategy is as follows: If, within three consecutive epochs, two or more update monitoring statistics exceed the threshold, the integrity monitoring module will determine that the ground-end satellite navigation receiver module is abnormal and subsequently exclude the pseudorange; if only the current update monitoring statistics exceed the threshold, the pseudorange will still pass monitoring in that epoch, but the input to the smoothing filter will not use the original calculation method, but will be changed as follows:

[0034]

[0035] Preferably, the threshold setting process is as follows:

[0036] 1) First, calculate the relationship between variance and elevation angle through polynomial fitting or exponential fitting, and then normalize it;

[0037] 2) Calculate the effective value (RMS) of the population from the normalized data, and obtain its inflation coefficient based on the inflation envelope of the Gaussian distribution or other distributions.

[0038] 3) Finally, thresholds are set based on the obtained normalized RMS and expansion coefficient, as well as the relationship between variance and elevation angle.

[0039] Preferably, the priority selection strategy is as follows:

[0040] Two matrices are established: a tracking matrix T and a decision matrix D. The elements in matrix T correspond to the pseudorange and carrier phase observations of each satellite, and matrix D represents the status of the elements in matrix T, including alarm, normal, and no tracking. Each pseudorange and carrier phase observation will have the following three situations: (a) one satellite corresponds to one pseudorange and carrier phase observation and an alarm flag is set; (b) one satellite corresponds to multiple pseudorange and carrier phase observations and an alarm flag is set; (c) multiple satellites correspond to one pseudorange and carrier phase observation and an alarm flag is set. If (b) or (c) is satisfied, the corresponding pseudorange and carrier phase observation is unavailable. If both (b) and (c) are satisfied, then the pseudorange and carrier phase observations used are unavailable. The availability of pseudorange and carrier phase observations for a satellite is determined by (a).

[0041] Once it is determined which pseudorange and carrier phase observations are excluded, an available set consisting of pseudorange, carrier phase observations, and satellites can be selected.

[0042] The base station observation dataset with the most available satellites among all base station observation datasets is selected for broadcast; if the number of available satellites is the same for each set of base station observation datasets, broadcasting is carried out according to the priority of the ground satellite navigation receiving module.

[0043] Preferably, the airborne platform guidance device includes an airborne satellite navigation receiver module, a satellite navigation rover, a data link, and a data link antenna;

[0044] The data link receives the observation dataset from the base station via the data link antenna and then transmits it to the satellite rover.

[0045] The aviation satellite navigation receiver module includes a high-precision satellite antenna and a receiver. The receiver receives satellite signals from the high-precision satellite antenna, and after filtering and amplification, transmits them to the satellite navigation rover via radio frequency lines.

[0046] The satellite navigation rover resolves satellite signals to obtain the rover's single-point positioning information. Combined with the base station's observation dataset, the relative positioning solution is obtained through differential calculation. The RTK baseline results, as well as the pitch and azimuth angles, are then transmitted to the aircraft platform's takeoff and landing guidance and control equipment.

[0047] The beneficial effects of this invention are as follows:

[0048] The multi-reference dynamic differential positioning take-off and landing guidance system proposed in this invention can stably provide accurate pseudorange and carrier phase observations, isolate satellite navigation reference station faults, and improve the accuracy and reliability of relative positioning data. Attached Figure Description

[0049] Figure 1This is a schematic diagram of a takeoff and landing guidance system based on multi-reference dynamic differential positioning. Detailed Implementation

[0050] The present invention will now be described in further detail with reference to the accompanying drawings and embodiments.

[0051] See Figure 1 As shown in the figure, the takeoff and landing guidance system based on multi-reference dynamic differential positioning in this embodiment includes a ground-end guidance device and an aircraft platform guidance device.

[0052] The ground-based guidance device includes several ground-based satellite navigation receiver modules, a satellite navigation reference station, an integrity monitoring module, a data link, and a data link antenna.

[0053] The aviation platform guidance device has an aviation-end satellite navigation receiver module, a satellite navigation rover, a data link, and a data link antenna.

[0054] In this embodiment, there are three ground-based satellite navigation receiving modules. Each ground-based satellite navigation receiving module contains a high-precision satellite antenna and a receiver. The receiver receives satellite signals from the high-precision satellite antenna, and after filtering and amplification, transmits them to the satellite navigation reference station via radio frequency lines.

[0055] The satellite navigation reference station performs RF front-end and baseband signal processing on the three satellite signals output from the ground-based satellite navigation receiver module, respectively, to calculate three sets of reference station observation datasets. These datasets include pseudorange and carrier phase observations provided by each satellite. The three sets of reference station observation datasets are then transmitted to the integrity monitoring module via an RS232 serial port.

[0056] The integrity monitoring module monitors the observation datasets of each set of base stations. Based on the fault judgment strategy, it determines whether the status of each carrier phase observation and pseudorange in each set of base station observation datasets is normal. After removing the faulty carrier phase observations and pseudoranges in each set of base station observation datasets, it selects the main base station observation dataset based on the priority selection strategy and sends the main base station observation dataset to the data link, which transmits it to the aviation platform through the data link antenna.

[0057] As an example, in this embodiment, the ground-based satellite navigation receiver modules are numbered REC1, REC2, and REC3, and the fault diagnosis strategy is as follows:

[0058] 1. Carrier accumulation - step size monitoring

[0059] Carrier accumulation-step monitoring can detect impulsive, step, and ramp faults in carrier phase observations, as well as excessive acceleration and other rapidly changing anomalies.

[0060] Define carrier phase correction The calculation method is as follows:

[0061]

[0062] Where m represents the ground-end satellite navigation receiver module number, and n represents the satellite number received by the ground-end satellite navigation receiver module. Let mn be the carrier phase observation given by the satellite at the current time k, and R be the carrier phase observation given by the satellite at the current time k. m,n Let τ be the geometric distance. m,n Correction number for the star clock. This is the carrier phase correction at the initial moment. When a cycle slip occurs or an abnormal restart happens, It must be recalculated, and subsequent corrections will be recalculated based on the new baseline.

[0063] By averaging and removing the influence of the clock bias of the ground-based satellite navigation receiver module, we can obtain:

[0064]

[0065] Among them, S m The ground-based satellite navigation receiver module m can receive N m The set of satellites, where j represents the satellite number received by the ground-end satellite navigation receiver module m. In multi-frequency, multi-system systems, the step of removing clock bias from the ground-end satellite navigation receiver module must be performed separately for each system and frequency. Given that the current time is k, the input observations for carrier-cumulative step-size monitoring are the carrier observations for ten consecutive epochs from k-9 to k. Furthermore, the location subset cannot change during these 10 epochs.

[0066] For carrier observations of ten consecutive epochs from k-9 to k A second-order least-squares fit is performed on it, and the fitting method is as follows:

[0067]

[0068] Where t represents the time interval elapsed relative to time k;

[0069] Therefore, the coefficients of the slope and acceleration terms at the current moment are:

[0070]

[0071] The step size (Step) is calculated as the deviation between the observed value at the current time k and the fitted result:

[0072]

[0073] Among them, T s Indicates the sampling period. This represents the prediction result obtained from the fitting formula calculation of the previous epoch.

[0074] If any of the slope, acceleration, and step size exceeds a threshold, an alarm flag is set at the corresponding ground-based satellite navigation receiver module, excluding the carrier phase observations of the corresponding satellite obtained from that ground-based satellite navigation receiver module.

[0075] A Gaussian distribution is used to dilate and enclose the obtained monitoring quantities of various types. In the monitoring module, the monitoring threshold is determined based on the obtained dilation coefficient and amplification factor. The processing steps are as follows:

[0076] First, the relationship between variance and elevation angle is calculated by polynomial or exponential fitting, and then normalized.

[0077] The effective value (RMS) of the population is calculated from the normalized data, and its inflation coefficient is obtained based on the inflation envelope of the Gaussian distribution or other distributions.

[0078] Finally, based on the obtained normalized RMS and expansion coefficient, as well as the relationship between variance and elevation angle, thresholds are set in the monitoring module.

[0079] Because the monitoring data eliminates the clock bias of the ground-based satellite navigation receiver module by removing the mean across different satellites, and also affects the estimated quantities through fitting over continuous time, this monitoring method exhibits strong correlation between observations from different satellites at the same time and over continuous time.

[0080] 2. Carrier-smoothed code phase measurement update monitoring

[0081] The carrier-smoothed code phase measurement update test detects pulse and step size errors in the original pseudorange measurement. The statistic for update monitoring is defined as:

[0082]

[0083] Where ρ represents the original pseudorange of the measurement, ρ s,m,n Carrier smoothing code phase measurement, ρ s,m,n The calculation method is as follows:

[0084]

[0085] in,

[0086] τ in normal circumstances s The value is 100s, and the sampling period is T. s In integrity monitoring systems, the value is typically taken as 0.5s.

[0087] The innovation monitoring strategy is as follows: If two or more innovation monitoring values ​​exceed the threshold within three consecutive epochs, the integrity monitoring module will determine that the channel is abnormal and subsequently exclude the measurement data. If only the current innovation monitoring value exceeds the threshold, the measurement data will still be monitored in that epoch, but the input to the smoothing filter will not use the original calculation method, but will instead be calculated as follows:

[0088]

[0089] Similarly, the steps for estimating the monitoring threshold are as follows:

[0090] 1) First, calculate the relationship between variance and elevation angle through polynomial fitting or exponential fitting, and then normalize it;

[0091] 2) Calculate the RMS of the population from the normalized data, and determine its inflation coefficient based on the inflation envelope of the Gaussian distribution or other distributions.

[0092] 3) Finally, based on the obtained normalized RMS and expansion coefficient, as well as the relationship between variance and elevation angle, the threshold is set in the monitoring module.

[0093] The priority selection strategy is as follows:

[0094] The first step is to establish two matrices: a tracking matrix (T) and a decision matrix (D). Elements in matrix T correspond to the pseudorange and carrier phase observations of each satellite, while matrix D represents the states of the elements in matrix T, including alarm, normal, and no tracking. Each pseudorange and carrier phase observation will exhibit one of three states: (a) one satellite corresponds to one pseudorange and carrier phase observation with an alarm flag set; (b) one satellite corresponds to multiple pseudorange and carrier phase observations with an alarm flag set; (c) multiple satellites correspond to one pseudorange and carrier phase observation with an alarm flag set. If (b) or (c) is satisfied, the corresponding pseudorange and carrier phase observation is unavailable. If both (b) and (c) are satisfied, then all used pseudorange and carrier phase observations are unavailable. In this case, it is unnecessary to attempt to determine if a pseudorange and carrier phase observation has malfunctioned, i.e., the set of base station observation datasets is faulty; it is necessary to switch to the next set of observation datasets. (a) can be used to determine whether the pseudorange and carrier phase observations for that satellite are available.

[0095] Once it is determined which pseudorange and carrier phase observations are excluded, an available set S consisting of pseudorange, carrier phase observations, and satellite data can be selected. c .

[0096] The following example illustrates S. cThe method for determining the satellites is as follows: First, a list of all tracked satellites is compiled, as shown in Table 1. Second, the attributes of the ground station satellite navigation receiver module and the corresponding satellites are identified. Unavailable satellites are indicated by '×', while satellites that are available are indicated by '√', and satellites that were not tracked are indicated by ' / '. Since differential positioning can be achieved by transmitting only one set of base station observation datasets, it is necessary to prioritize multiple sets of base station observation datasets. The priority of each set of base station observation datasets is evaluated through data quality analysis of the base stations.

[0097] Screening criteria for multiple sets of baseline observation data:

[0098] 1. Select the base station observation dataset with the most available satellites from each base station observation dataset and broadcast it;

[0099] 2. If the number of available satellites for each set of base station observation datasets is the same, broadcasting shall be carried out according to the priority (numbering order) of the ground-end satellite navigation receiving modules.

[0100] Table 1

[0101] REC1 √ √ √ √ √ √ √ √ √ √ / × REC2 √ √ √ √ √ √ √ √ √ / √ √ REC3 √ √ √ √ √ √ √ √ √ / √ ×

[0102] On the airborne platform, the data link receives the observation dataset from the base station via the data link antenna and transmits it to the satellite rover via RS232 serial port or Ethernet.

[0103] The aerospace satellite navigation receiver module includes a high-precision satellite antenna and a receiver. The receiver receives satellite signals from the high-precision satellite antenna, and after filtering and amplification, transmits them to the satellite navigation rover via radio frequency lines.

[0104] The satellite navigation rover resolves satellite signals to obtain the rover's single-point positioning information. Combined with the base station's observation dataset, the relative positioning solution is obtained through differential calculation. The RTK baseline results, as well as pitch and azimuth angles, are then transmitted to the aircraft platform's takeoff and landing guidance and control equipment.

[0105] It is understood that those skilled in the art can make equivalent substitutions or modifications to the technical solution and inventive concept of the present invention, and all such substitutions or modifications should fall within the protection scope of the appended claims.

Claims

1. A takeoff and landing guidance system based on multi-reference dynamic differential positioning, comprising a ground-end guidance device and an aircraft platform guidance device, characterized in that: The ground-based guidance device includes several ground-based satellite navigation receiver modules, one satellite navigation reference station, one integrity monitoring module, one data link, and one data link antenna. Each ground-based satellite navigation receiver module contains a high-precision satellite antenna and a receiver. The receiver receives satellite signals from the high-precision satellite antenna, and after filtering and amplification, transmits them to the satellite navigation reference station via radio frequency lines. The satellite navigation reference station performs radio frequency front-end and baseband signal processing on the satellite signals output by the satellite navigation receiving modules at each ground end, and calculates the reference station observation dataset. The reference station observation dataset includes pseudorange and carrier phase observations provided by each satellite; each set of reference station observation datasets is transmitted to the integrity monitoring module. The integrity monitoring module monitors the observation datasets of each set of base station data. Based on a fault diagnosis strategy, it determines whether the status of each carrier phase observation and pseudorange in each set of base station observation datasets is normal. After removing faulty carrier phase observations and pseudoranges from each set of base station observation datasets, it selects the master base station observation dataset according to a priority selection strategy. The master base station observation dataset is then sent to the data link, and transmitted via the data link antenna to the flight platform for takeoff and landing guidance calculations. The priority selection strategy is as follows: Two matrices are established: a tracking matrix T and a decision matrix D. The elements in matrix T correspond to the pseudorange and carrier phase observations of each satellite, and matrix D represents the status of the elements in matrix T, including alarm, normal, and no tracking. Each pseudorange and carrier phase observation will have the following three situations: (a) one satellite corresponds to one pseudorange and carrier phase observation and an alarm flag is set; (b) one satellite corresponds to multiple pseudorange and carrier phase observations and an alarm flag is set; (c) multiple satellites correspond to one pseudorange and carrier phase observation and an alarm flag is set. If (b) or (c) is satisfied, the corresponding pseudorange and carrier phase observation is unavailable. If both (b) and (c) are satisfied, then the pseudorange and carrier phase observations used are unavailable. The availability of pseudorange and carrier phase observations for a satellite can be determined by (a). Once it is determined which pseudorange and carrier phase observations are excluded, an available set consisting of pseudorange, carrier phase observations, and satellites can be selected. The base station observation dataset with the most available satellites among all base station observation datasets is selected for broadcast; if the number of available satellites is the same for each set of base station observation datasets, broadcasting is carried out according to the priority of the ground satellite navigation receiving module.

2. The takeoff and landing guidance system based on multi-reference dynamic differential positioning according to claim 1, characterized in that... The fault diagnosis strategy is as follows: 1) Carrier accumulation - step size monitoring: Define carrier phase correction The calculation method is as follows: Where m represents the ground-end satellite navigation receiver module number, and n represents the satellite number received by the ground-end satellite navigation receiver module. Let mn be the carrier phase observation given by the satellite at the current time k. For geometric distance, Correction number for the star clock. This represents the carrier phase correction at the initial moment. By averaging and removing the influence of clock bias from the ground-based satellite navigation receiver module, we obtain: in, It was received by the ground-based satellite navigation receiver module m. The set of satellites, where j represents the satellite number received by the ground-based satellite navigation receiver module m; For carrier observations over several consecutive epochs We then perform a second-order least-squares fit on it, as follows: Where t represents the time interval elapsed relative to time k; Therefore, the coefficients of the slope and acceleration terms at the current moment are: The step size monitoring value is calculated as the deviation between the observed value at the current time k and the fitting result: in, Indicates the sampling period. This represents the prediction result obtained from the fitting formula calculation in the previous epoch; If any of the slope, acceleration, and step size exceeds the threshold, an alarm flag is set at the corresponding ground-end satellite navigation receiver module to exclude the carrier phase observations of the corresponding satellite obtained from that ground-end satellite navigation receiver module. 2) Carrier smoothing code phase measurement update monitoring: The statistical measure for updating monitoring is defined as follows: in, Indicates pseudorange, Carrier smoothing code phase measurement, The calculation method is as follows: in, The update monitoring judgment strategy is as follows: If, within three consecutive epochs, two or more update monitoring statistics exceed the threshold, the integrity monitoring module will determine that the ground-end satellite navigation receiver module is abnormal and subsequently exclude the pseudorange; if only the current update monitoring statistics exceed the threshold, the pseudorange will still pass monitoring in that epoch, but the input to the smoothing filter will not use the original calculation method, but will be changed as follows: 。 3. A takeoff and landing guidance system based on multi-reference dynamic differential positioning according to claim 2, characterized in that... The threshold setting process is as follows: 1) First, calculate the relationship between variance and elevation angle through polynomial fitting or exponential fitting, and then normalize it; 2) Calculate the effective value (RMS) of the population from the normalized data, and obtain its inflation coefficient based on the inflation envelope of the Gaussian distribution or other distributions; 3) Finally, thresholds are set based on the obtained normalized RMS and expansion coefficient, as well as the relationship between variance and elevation angle.

4. The takeoff and landing guidance system based on multi-reference dynamic differential positioning according to claim 1, characterized in that... The airborne platform guidance device includes an airborne satellite navigation receiver module, a satellite navigation rover, a data link, and a data link antenna; The data link receives the observation dataset from the base station via the data link antenna and then transmits it to the satellite rover. The aviation satellite navigation receiver module includes a high-precision satellite antenna and a receiver. The receiver receives satellite signals from the high-precision satellite antenna, and after filtering and amplification, transmits them to the satellite navigation rover via radio frequency lines. The satellite navigation rover resolves satellite signals to obtain the rover's single-point positioning information. Combined with the base station's observation dataset, the relative positioning solution is obtained through differential calculation. The RTK baseline results, as well as the pitch and azimuth angles, are then transmitted to the aircraft platform's takeoff and landing guidance and control equipment.

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