Recycling positioning measurement system based on dynamic differential and optical measurement combined positioning

Abstract

The application discloses a recovery positioning measurement system based on dynamic differential and optical measurement combined positioning, which comprises a Beidou differential positioning device, a navigation antenna, real-time self-positioning measurement based on the Beidou global navigation system, output of absolute positioning results of a rocket system, satellite reference information collected by a differential antenna and dynamic reference recovery platform self-positioning information sent by the rocket system, pseudo-range differential and carrier phase differential relative positioning, satellite relative positioning results, an optical fusion system, optical beacon information collection, output of optical relative positioning results, a data synthesis device, output of integrated relative positioning results to the rocket system, a rocket system, a data transmission device and a data transmission antenna, information sent by a ground data transmission device is received and demodulated, dynamic reference recovery platform self-positioning information is analyzed out, and rocket control is carried out according to the absolute positioning results and the integrated relative positioning results. The application provides positioning precision.

Description

Technical Field

[0001] This invention relates to a recovery positioning and measurement system based on combined positioning of dynamic differential and optical measurements, belonging to the field of navigation technology for recoverable launch vehicles. Background Technology

[0002] Launch vehicles are the primary means by which humanity explores space and strives to become a spacefaring power. Compared to expendable launch vehicles, launch vehicles, after completing their mission from launch, return to Earth, land, undergo maintenance and refueling, and can then be launched again, making them more economical and environmentally friendly. In reusable vertical return missions, the first stage of a reusable launch vehicle exhibits characteristics of large airspace, high dynamics, and high Mach speeds. Conventional satellite / inertial navigation systems face challenges during the return phase due to factors such as vehicle disturbances, continuous reversals, and blackouts. These challenges, coupled with the recovery process and the ballistic characteristics of the recovered stages, further complicate rocket recovery.

[0003] Dynamic relative positioning relative to a moving reference station, also known as moving-to-moving positioning, has a wide range of applications, such as fleet management, battlefield command, formation flying, relative positioning of moving vehicles, satellite-to-satellite orbit determination, aircraft installation and approach, collision avoidance, and autopilot. In these applications, traditional positioning methods (such as radar / laser ranging) are either not accurate enough or have strict limitations and cannot fully meet the requirements.

[0004] Building upon traditional satellite positioning, this system, based on the BeiDou Navigation Satellite System, employs pseudorange differential and carrier phase differential algorithms to ensure the real-time performance and accuracy of the recovery positioning results. Optical fusion technology further enhances the reliability of the recovery positioning. Compared to traditional positioning technologies, this recovery positioning measurement technology, based on dynamic differential and optical measurement, utilizes a redundant positioning architecture, pseudorange differential and carrier phase differential relative positioning technologies, dynamic position prediction methods, and adaptive optical fusion technology. This achieves a highly real-time, high-precision, and highly reliable recovery positioning system design, providing precise and reliable absolute and relative navigation information for rocket recovery on the motion platform. This improves the navigation accuracy of the first stage, reduces the dispersion of the rocket stage's landing point under various deviation conditions and disturbances, and lays the foundation for the targeted recovery and reuse of the rocket stage.

[0005] Currently, overseas recovery positioning and measurement methods use traditional GPS positioning, which has low measurement accuracy. The accuracy of the recovery and landing phase is ensured by inertial navigation devices, and this method is only suitable for rockets of medium and lower weight. Domestic recovery positioning uses a static reference, where the precise location of the landing target is known. Visual fusion or conventional differential algorithms can meet the accuracy requirements, but this method is not suitable for the high precision, high dynamics, and high reliability requirements of dynamic-to-dynamic recovery scenarios. Summary of the Invention

[0006] The technical problem solved by the present invention is to overcome the shortcomings of the prior art and provide a recovery positioning measurement system based on dynamic differential and optical measurement, which improves the high accuracy of recovery positioning.

[0007] The technical solution of this invention is:

[0008] This invention discloses a recovery positioning and measurement system based on dynamic differential and optical measurement joint positioning, comprising: a BeiDou differential positioning device, an optical fusion system, a data integration device, a rocket system, a data transmission device, a data transmission antenna, a navigation antenna, a ground data transmission device, a differential antenna, and a BeiDou reference device; wherein,

[0009] The BeiDou differential positioning equipment performs real-time self-positioning measurements based on the BeiDou global navigation system through the navigation antenna, and outputs the absolute positioning results of the rocket system; it performs pseudorange differential and carrier phase differential relative positioning by collecting BeiDou satellite reference information through the differential antenna and the dynamic reference recovery platform self-positioning information sent by the rocket system, and obtains the satellite relative positioning results; the absolute positioning results and the satellite relative positioning results are sent to the data integration equipment.

[0010] The optical fusion system collects optical beacon information, outputs optical relative positioning results, and sends them to the data integration equipment.

[0011] The data integration equipment obtains a comprehensive relative positioning result based on the satellite relative positioning result output by the Beidou differential positioning equipment and the optical relative positioning result sent by the optical fusion system, and outputs it to the rocket system; it also forwards the absolute positioning result to the rocket system.

[0012] The rocket system receives and demodulates information sent by ground-based data transmission equipment via data transmission devices and antennas, extracts the self-positioning information of the dynamic reference recovery platform, and sends it to the BeiDou differential positioning equipment; it then controls the rocket based on the absolute positioning results and the comprehensive relative positioning results.

[0013] Furthermore, in the above system, the satellite relative positioning result is specifically as follows:

[0014]

[0015]

[0016]

[0017] in, and These represent adjacent observation times during the rocket's motion; y represents the PDOT observation model; superscript , These represent satellite numbers respectively; These are inter-satellite differential carrier phase observations; This represents the corresponding inter-satellite differential geometric distance. At the speed of light, The satellite clock bias is calculated from the broadcast ephemeris parameters; For the observation time The position of the rocket, For the observation time The position of the rocket; This represents the position increment of the mobile station at adjacent time points; This is the weight matrix for the inter-satellite differential carrier phase; This is the line-of-sight matrix.

[0018] Furthermore, in the above system, the gaze matrix is ​​specifically:

[0019]

[0020]

[0021] in, For the line-of-sight matrix, It is a time variable.

[0022] Furthermore, in the above system, the process of obtaining a comprehensive relative positioning result based on the satellite relative positioning result output by the BeiDou differential positioning device and the optical relative positioning result sent by the optical fusion system specifically involves:

[0023] Satellite relative positioning results include carrier phase differential satellite relative positioning results and pseudorange differential satellite relative positioning results;

[0024] The priorities of the relative positioning results of carrier phase differential satellite, optical relative positioning results, pseudorange differential satellite relative positioning results, and absolute positioning results of rocket system are determined sequentially as Y1, Y2, Y3, and Y4, respectively; where Y1 > Y2 > Y3 > Y4.

[0025] When one or more positioning results are available, including carrier phase differential satellite relative positioning results, optical relative positioning results, pseudorange differential satellite relative positioning results, and rocket system absolute positioning results, they are sorted according to priority, and the positioning result corresponding to the highest priority is output as the comprehensive relative positioning result.

[0026] Furthermore, in the above system, the optical fusion system includes several optical detectors, optical information processing equipment, and several optical beacons; wherein,

[0027] The optical detector captures the signal of the optical beacon in real time during the rocket recovery and landing phase, and transmits the optical beacon to the optical information processing equipment in real time.

[0028] The optical information processing equipment performs image matching on the optical beacon and uses a pose calculation algorithm to output the optical relative positioning result, which is then sent to the data integration equipment.

[0029] Furthermore, in the above system, the optical relative positioning result is specifically as follows:

[0030]

[0031]

[0032] in, The image shows the optical relative positioning result of the rocket at time t, where N is the total number of cameras and n is the total number of beacons observed by each camera at time t. for and The linear equation, Let t be the slant range between camera k and beacon i, and t be the positioning time. Let be the measured straight-line distance between beacon i and the beacon center point. Let be the straight-line distance between beacon i and the center point of the beacon in the image captured by camera k at time t. Number the camera This is the beacon number.

[0033] Furthermore, in the above system, each optical detector includes a large field-of-view camera and a small field-of-view camera; the large field-of-view camera has a focal length of 10~12mm and both vertical and horizontal field of view are 45°~56.1°; the small field-of-view camera has a focal length of 20~35mm and both vertical and horizontal field of view are 15°~20.7°.

[0034] Furthermore, in the above system, each optical beacon is powered by an independent power supply.

[0035] The advantages of this invention over the prior art are as follows:

[0036] (1) The present invention constructs a positioning architecture with redundancy features, utilizes pseudorange differential and carrier phase differential relative positioning technology, dynamic position prediction method and adaptive optics fusion technology, and realizes the design of a recovery positioning system with strong real-time, high precision and high reliability.

[0037] (2) This invention constructs a differential relative positioning system architecture based on the Beidou satellite navigation system with redundancy characteristics. It adopts a method that combines pseudorange differential and carrier phase differential relative positioning technologies. This solves the positioning instability problem caused by the large airspace, high dynamics, and high Mach flight characteristics of the first stage of the rocket during the recovery and landing phase, as well as factors such as rocket body disturbance, continuous reversal, blackout, total reflection of the sea surface, and flame reversal. It also solves the problem of high-precision positioning during recovery.

[0038] (3) The present invention constructs a dynamic position prediction method, which adopts a real-time dynamic recursion strategy and combines a time sliding window polynomial fitting method to perform short-time recursion processing on dynamic reference equipment and dynamic mobile equipment respectively. Combined with the data information of the previous moment, the relative position information of the current dynamic reference equipment and dynamic mobile equipment is estimated, thus realizing strong real-time performance of retrieval positioning.

[0039] (4) This invention employs an adaptive optical fusion technology. By deploying a four-diversity optical detector and an optical information processing device on the recovery and return equipment, and an optical beacon on the recovery platform, high-precision positioning in the near-platform area of ​​the recovery landing segment is achieved. This effectively solves the problem of unstable positioning caused by interference factors such as flame flipping, water vapor ionization, and total internal reflection of seawater. The optical information processing device adopts an adaptive availability evaluation criterion to comprehensively screen the visual capture results of the large field-of-view camera and the small field-of-view camera and perform algorithm fusion, thus solving the problem of high-precision positioning during marine recovery.

[0040] (5) The present invention adopts a recovery positioning measurement technology based on dynamic differential + optical measurement, which realizes a real-time recovery positioning measurement accuracy of less than 1 meter in a marine recovery scenario where the motion acceleration of the recovered mobile device is 5g / s, the jerk is 2g / s2, and the relative distance is 3 kilometers. Attached Figure Description

[0041] Figure 1 This is a diagram of the architecture of the recovery positioning and measurement system based on dynamic differential and optical measurement combined positioning of the present invention;

[0042] Figure 2 This is a schematic diagram illustrating the data transmission and processing delay of the present invention;

[0043] Figure 3 This is a flowchart of the time-sliding window polynomial dynamic reference position prediction algorithm of the present invention;

[0044] Figure 4 This is a block diagram of the adaptive optics fusion system of the present invention;

[0045] Figure 5 This is a schematic diagram of the installation of the optical detector of the present invention; (a) side view, (b) top view;

[0046] Figure 6 This is a plan view of the optical beacon layout of the present invention;

[0047] Figure 7 This is a coordinate diagram of the optical beacon layout of the present invention. Detailed Implementation

[0048] The present invention will be further described in detail below with reference to the accompanying drawings and specific embodiments.

[0049] This invention discloses a recovery positioning and measurement system based on dynamic differential and optical measurement joint positioning, comprising: a BeiDou differential positioning device, an optical fusion system, a data integration device, a rocket system, a data transmission device, a data transmission antenna, a navigation antenna, a ground data transmission device, a differential antenna, and a BeiDou reference device; wherein,

[0050] The BeiDou differential positioning equipment performs real-time self-positioning measurements based on the BeiDou global navigation system through the navigation antenna, and outputs the absolute positioning results of the rocket system; it performs pseudorange differential and carrier phase differential relative positioning by collecting BeiDou satellite reference information through the differential antenna and the dynamic reference recovery platform self-positioning information sent by the rocket system, and obtains the satellite relative positioning results; the absolute positioning results and the satellite relative positioning results are sent to the data integration equipment.

[0051] The optical fusion system collects optical beacon information, outputs optical relative positioning results, and sends them to the data integration equipment.

[0052] The data integration equipment obtains a comprehensive relative positioning result based on the satellite relative positioning result output by the Beidou differential positioning equipment and the optical relative positioning result sent by the optical fusion system, and outputs it to the rocket system; it also forwards the absolute positioning result to the rocket system.

[0053] The rocket system receives and demodulates information sent by ground-based data transmission equipment via data transmission devices and antennas, extracts the self-positioning information of the dynamic reference recovery platform, and sends it to the BeiDou differential positioning equipment; it then controls the rocket based on the absolute positioning results and the comprehensive relative positioning results.

[0054] Preferably, the satellite relative positioning result is as follows:

[0055]

[0056]

[0057]

[0058] in, and These represent adjacent observation times during the rocket's motion; y represents the PDOT observation model; superscript , These represent satellite numbers respectively; These are inter-satellite differential carrier phase observations; This represents the corresponding inter-satellite differential geometric distance. At the speed of light, The satellite clock bias is calculated from the broadcast ephemeris parameters; For the observation time The position of the rocket, For the observation time The position of the rocket; This represents the position increment of the mobile station at adjacent time points; This is the weight matrix for the inter-satellite differential carrier phase; This is the line-of-sight matrix.

[0059] Preferably, the line-of-sight matrix is ​​as follows:

[0060]

[0061]

[0062] in, For the line-of-sight matrix, It is a time variable.

[0063] Preferably, a comprehensive relative positioning result is obtained based on the satellite relative positioning result output by the BeiDou differential positioning device and the optical relative positioning result sent by the optical fusion system, specifically as follows:

[0064] Satellite relative positioning results include carrier phase differential satellite relative positioning results and pseudorange differential satellite relative positioning results;

[0065] The priorities of the relative positioning results of carrier phase differential satellite, optical relative positioning results, pseudorange differential satellite relative positioning results, and absolute positioning results of rocket system are determined sequentially as Y1, Y2, Y3, and Y4, respectively; where Y1 > Y2 > Y3 > Y4.

[0066] When one or more positioning results are available, including carrier phase differential satellite relative positioning results, optical relative positioning results, pseudorange differential satellite relative positioning results, and rocket system absolute positioning results, they are sorted according to priority, and the positioning result corresponding to the highest priority is output as the comprehensive relative positioning result.

[0067] Preferably, the optical fusion system includes several optical detectors, optical information processing equipment, and several optical beacons; wherein,

[0068] The optical detector captures the signal of the optical beacon in real time during the rocket recovery and landing phase, and transmits the optical beacon to the optical information processing equipment in real time.

[0069] The optical information processing equipment performs image matching on the optical beacon and uses a pose calculation algorithm to output the optical relative positioning result, which is then sent to the data integration equipment.

[0070] Preferably, the optical relative positioning result is as follows:

[0071]

[0072]

[0073] in, The image shows the optical relative positioning result of the rocket at time t, where N is the total number of cameras and n is the total number of beacons observed by each camera at time t. for and The linear equation, Let t be the slant range between camera k and beacon i, and t be the positioning time. Let be the measured straight-line distance between beacon i and the beacon center point. Let be the straight-line distance between beacon i and the center point of the beacon in the image captured by camera k at time t. Number the camera This is the beacon number.

[0074] Preferably, each optical detector includes a large field-of-view camera and a small field-of-view camera; the large field-of-view camera has a focal length of 10~12mm and both vertical and horizontal field of view angles of 45°~56.1°; the small field-of-view camera has a focal length of 20~35mm and both vertical and horizontal field of view angles of 15°~20.7°.

[0075] Preferably, each optical beacon is powered by an independent power source.

[0076] Example

[0077] like Figure 1 As shown, the recovery positioning measurement system based on dynamic differential positioning + optical measurement joint positioning consists of the following components: data integration equipment, optical information processing equipment, optical detector, data transmission equipment, BeiDou differential positioning equipment, data transmission antenna, differential antenna, navigation antenna, ground data transmission equipment, BeiDou reference equipment, and optical beacon.

[0078] The workflow for recovery positioning measurement based on dynamic differential positioning and optical measurement is as follows:

[0079] In the dynamic-to-dynamic recovery positioning and measurement system, the BeiDou reference information on the dynamic reference recovery platform performs real-time self-positioning measurements based on the BeiDou Global Navigation Satellite System. This BeiDou reference information is transmitted wirelessly via ground data transmission equipment and antennas. The dynamic rocket receives and demodulates the wireless information transmitted from the ground through its data transmission antenna and equipment, extracts the self-positioning information of the dynamic reference recovery platform, and transmits it to the BeiDou differential positioning equipment.

[0080] The BeiDou differential positioning device performs real-time self-positioning measurements based on the BeiDou Global Navigation Satellite System using a navigation antenna, outputting absolute positioning results. Simultaneously, it collects BeiDou satellite reference information using a differential antenna. By combining the self-collected BeiDou satellite reference information with that collected by a dynamic reference retrieval platform, pseudorange differential and carrier phase differential relative positioning are performed. This, along with a dynamic position prediction method, improves the accuracy and real-time performance of the relative positioning results.

[0081] The four-diversity optical detector employs optical beacon measurement technology to capture optical beacon signal images in real time during the rocket's recovery and landing phase. It then extracts the optical beacon images and transmits the image information to the optical information processing equipment in real time. The optical information processing equipment performs image matching on the beacon image information and uses a pose calculation algorithm to output the relative positioning result.

[0082] The data integration equipment integrates the pseudorange differential and carrier phase differential relative positioning results output by the Beidou differential positioning equipment and the optical fusion relative positioning results output by the optical information processing equipment. During the rocket ascent and recovery phases, it outputs the rocket's self-positioning absolute positioning results for flight assistance, and during the recovery and landing phase, it outputs highly reliable and high-precision real-time positioning results for recovery positioning measurement.

[0083] Pseudorange differential positioning utilizes pseudorange observations for double-difference processing to calculate the baseline vector between the dynamic reference device and the mobile receiving device, thereby achieving high-precision real-time positioning of the mobile receiving device.

[0084] At epoch k, the pseudorange observation equation is as follows:

[0085]

[0086] in, Indicates pseudo-distance observations, This indicates the actual distance between the dynamic reference device and the satellite. Represents the speed of light. Indicates receiver clock bias. Indicates satellite clock bias, Indicates satellite orbital error. This represents the Earth's rotation correction value. Indicates ionospheric delay error. Indicates tropospheric delay error. This represents pseudorange observation noise and multipath error.

[0087] Based on the double-difference principle, in short baseline measurements, the propagation paths from the same satellite to different antennas can be considered the same. Therefore, the resulting double-difference observation equations only contain observation noise and multipath error. The double-difference observation equations are as follows:

[0088]

[0089] The number of satellites viewed together is At that time, each epoch can establish A pseudorange double-difference equation system is established. The double-difference observation equations are linearized, and a system of pseudorange double-difference equations is constructed for different epochs t:

[0090]

[0091] In the formula, It is the coefficient matrix of the carrier phase and pseudorange double difference equation system at epoch t, ​​with the following number of rows. There are 3 columns; It is the three-dimensional coordinate correction vector of the receiver at epoch t, ​​with an order of 3; It is a constant term vector with order . , where is the residual matrix of the pseudorange double-difference observation equation at epoch t.

[0092] Since pseudorange observations do not have ambiguity issues and have high accuracy, the relative position information between the dynamic reference device and the mobile receiving device can be obtained by using least squares processing.

[0093] Carrier phase differential positioning mainly uses pre-processed raw observations, combines pseudorange and carrier phase observations to solve double-difference integer ambiguity values, and calculates the baseline vector between the dynamic reference device and the mobile receiving device antenna, thereby achieving high-precision real-time positioning of the carrier.

[0094] At epoch k, the pseudorange and carrier phase observation equations are as follows:

[0095]

[0096] in, Indicates pseudo-distance observations, Indicates the carrier wavelength. Represents the carrier phase observation value. This represents the initial integer ambiguity. This indicates the actual distance between the dynamic reference device and the satellite. Represents the speed of light. Indicates receiver clock bias. Indicates satellite clock bias, Indicates satellite orbital error. This represents the Earth's rotation correction value. Indicates ionospheric delay error. Indicates tropospheric delay error. This represents pseudorange observation noise and multipath error. This represents carrier phase observation noise and multipath error.

[0097] Based on the double-difference principle, in short baseline measurements, the propagation paths from the same satellite to different antennas can be considered the same. Therefore, the resulting double-difference observation equations only contain observation noise and multipath error. The double-difference observation equations are as follows:

[0098]

[0099] The number of satellites viewed together is At that time, each epoch can establish The carrier phase double difference equation and A pseudorange double-difference equation. The double-difference observation equations are linearized, and carrier phase double-difference and pseudorange double-difference equation systems are established for different epochs t:

[0100]

[0101] In the formula, , It is the coefficient matrix of the carrier phase and pseudorange double difference equation system at epoch t, ​​with the following number of rows. There are 3 columns; is the three-dimensional coordinate correction vector of the receiver at epoch t, ​​with an order of 3; A is the ambiguity design matrix, which can be chosen as A=E (E is the identity matrix) when only the phase observations are considered. It is the integer ambiguity vector of the wide-lane carrier phase, with order . This is a constant vector that is independent of the change in epoch t. If we assume that the number of satellites observed in each epoch is the same, then the order remains unchanged. This is acceptable in the short term. For convenience, we will apply this assumption. and It is a constant term vector with order . , are the residual matrices of the carrier phase double difference and pseudorange double difference observation equations for the t-th epoch, respectively.

[0102] Dual-frequency receivers can obtain pseudorange observations in addition to carrier phase observations. Pseudorange observations are free from ambiguity and have high accuracy. Therefore, pseudorange observations can be used to improve the strength of the positioning equations. The double-difference observation equations for pseudorange and carrier phase are as follows:

[0103]

[0104] In the formula, It is the design matrix of the carrier phase double-difference observation equation for the t-th epoch. It is the design matrix of the pseudorange double-difference observation equation at epoch t. It is the residual vector matrix of the phase observation vector at epth t. It is the residual vector matrix of the phase observation vector at epth t. It is the three-dimensional coordinate correction vector of the receiver at epoch t, ​​with an order of 3. It is the value of the double-difference carrier phase integer ambiguity. It is a unit array. The number of epochs used to establish the current double-difference observation equation.

[0105] For multiple observations, new "observations," also known as virtual observations, can be obtained through linear combination. These observations should meet at least one of the following criteria:

[0106] 1) The observed values ​​after linear combination should be able to maintain the integer property of ambiguity in order to facilitate the initialization of ambiguity;

[0107] 2) The observed values ​​after linear combination should have appropriate wavelengths;

[0108] 3) The observations after linear combination should be unaffected or substantially unaffected by ionospheric delay;

[0109] 4) The observed values ​​after linear combination should have low measurement noise.

[0110] Based on the above principles, wide-lane observations can be constructed using a linear combination of dual-frequency data. In this scheme, pseudorange observations and wide-lane carrier phase observations are combined to first calculate the wide-lane ambiguity value. The normal equation is then constructed based on the above equation set:

[0111]

[0112] In the formula, and These are the weight matrices for the carrier phase double difference and pseudorange double difference at epoch t, ​​respectively. The normal equation is divided into blocks according to the dashed lines in the formula. Only the ambiguity sub-block is calculated, and matrix decomposition is performed. The intermediate process is omitted, and the estimation formula for the wide-lane carrier phase ambiguity is given directly as follows:

[0113]

[0114] In the formula:

[0115]

[0116] The cofactor matrix of the real solution to the wide-lane carrier phase ambiguity is:

[0117]

[0118] Based on the floating-point solution of the carrier phase ambiguity and the corresponding covariance matrix, the LAMBDA method is used for searching. That is, the real solution of the wide-lane carrier phase ambiguity and the cofactor matrix of the real solution are used as input conditions for the LAMBDA method. After searching, the integer solution of the wide-lane carrier phase integer ambiguity is obtained.

[0119] Integer solutions using wide-lane integer ambiguity Ambiguity decomposition is performed according to the relationship shown in the following formula to obtain the double-difference integer ambiguity of the B1 / B3 carrier phase. , ).

[0120]

[0121] The B1 / B3 carrier double-difference observations obtained after wide-lane carrier phase ambiguity decomposition can be used to measure the relative position between two points, and obtain the baseline vector between the dynamic reference device and the mobile receiving device antenna, i.e., the relative positioning result.

[0122] Dynamic position prediction method

[0123] To address latency and link reliability, a dynamic position estimation method is employed. This method involves short-term recursion of the positions of the dynamic reference device and the mobile receiving device to obtain real-time relative position information. The dynamic position estimation method is attached. Figure 4 As shown.

[0124] Dynamic reference position prediction

[0125] High-precision differential positioning technology requires the use of information from both the platform's dynamic reference device and the mobile receiving device at the same time to calculate the relative positioning result corresponding to the data at that moment. It includes two operating modes: pseudorange differential positioning (RTD) and carrier phase differential positioning (RTK). In practical use, after the platform's dynamic reference device completes data acquisition and positioning, it transmits the data to the mobile receiving device via a wireless link between the arrow and the ground. Upon receiving the data from the platform's dynamic reference device, the mobile receiving device performs relative positioning processing using data from the same time as the platform's dynamic reference device and outputs the relative positioning result.

[0126] Appendix Figure 2 The data transmission and processing sequence is defined by T0 and T1, representing the corresponding times for the data. After completing navigation and positioning at time T0, the platform's dynamic reference device transmits the data to the mobile receiving device via a wireless link. The mobile receiving device receives the data from the platform's dynamic reference device at time T1, performs calculations, and outputs the relative positioning result from time T0 at time T2.

[0127] The time delay of the mobile receiving device transmitting relative positioning results consists of three main parts: the data transmission time of the dynamic reference device, the wireless link transmission time, and the calculation time of the mobile receiving device.

[0128] In recovery scenarios, high-real-time and high-precision relative positioning measurements are required. Since both the platform's dynamic reference equipment and the recovery rocket are in motion, the relative positioning technology used by conventional fixed dynamic reference equipment has the following shortcomings:

[0129] The dynamic reference device is not completely stationary, so its coordinates cannot be calibrated and provided to the rover station.

[0130] Dynamic mobile devices can only perform relative positioning processing after receiving dynamic reference device information transmitted via wireless link. Due to the influence of wireless link transmission, there will inevitably be a delay in output data.

[0131] Based on the above issues, differential positioning technology can achieve high-precision relative positioning measurements. Considering the characteristics of the dynamic reference equipment in this task—minimal dynamics and only affected by waves along with the barge—a real-time dynamic recursive strategy is proposed. This strategy involves performing short-time recursive processing on both the dynamic reference equipment and the dynamic mobile equipment, and then combining the data from the previous moment to estimate the current relative position information of the dynamic reference equipment and the dynamic mobile equipment.

[0132] A time-sliding window polynomial fitting method is employed to predict the position information of a dynamic reference device. This method predicts the future motion state of the target by processing a historical data sequence of the target's motion state, and continuously slides forward as the data is updated. Assuming the target's motion is in a state of variable acceleration, a function satisfying a cubic polynomial is used for fitting the motion state, specifically:

[0133]

[0134] In equation (15), the independent variable For time variables, the unit is seconds; , , and These are the coefficients of the polynomial.

[0135] For the original time If normalization is performed, then

[0136]

[0137] In the formula, .

[0138] Solving the above equation using the least squares method, we can write it in matrix form as follows:

[0139]

[0140] In the formula,

[0141]

[0142] The vector of coefficient values ​​to be solved. For observations

[0143] Vector This is the observation state error vector.

[0144] Substitute the absolute position coordinates of the carrier into equation (17) to obtain the polynomial coefficients and predict the state value at the required time. When making a new prediction, replace the original data with the new n sets of data to achieve continuous sliding prediction. The specific algorithm is shown in the appendix. Figure 3 As shown.

[0145] Mobile station location recursion

[0146] The mobile station uses an interepoch differential recursion method to calculate the current location information of the mobile station by combining the positioning results of the mobile station at the previous time step.

[0147] The inter-epoch differential recursion adopts the PDOT positioning model, and the receiver clock bias and hardware delay parameters can be eliminated using an inter-satellite single-difference elimination strategy. When the sampling rate of the mobile receiving equipment is not less than 1Hz and the carrier's movement speed is limited, the inter-epoch differential can significantly reduce the impact of slowly changing and spatially correlated ionospheric and tropospheric errors. Ambiguity parameters are invariant when the carrier phase observations do not experience cycle slips, and can be eliminated by differencing the observations from one time point to the next. Assume that adjacent observation times of the mobile station are... and The PDOT observation model can be abbreviated as:

[0148] (18)

[0149] In the formula, superscript , These represent satellite numbers respectively; These are inter-satellite differential carrier phase observations; This represents the corresponding inter-satellite differential geometric distance. At the speed of light, This refers to satellite clock bias.

[0150] Satellite clock bias inter-satellite difference term in equation (18) Calculated from broadcast ephemeris parameters. Substituting the absolute value of the rover station at the previous moment into equation (18) as the initial value for linearizing the observation equation, we have:

[0151]

[0152] In the formula,

[0153]

[0154] This is the line-of-sight matrix.

[0155] Based on equation (19), the least squares method is used to obtain the position increment of the mobile station at adjacent times as follows:

[0156]

[0157] In the formula, This is the weight matrix for the inter-satellite differential carrier phase.

[0158] According to equation (20), the position increment between adjacent time points is calculated, and then combined with the relative position of the mobile station at the previous time point, the relative position of the mobile station at the current time point can be obtained:

[0159]

[0160] In the formula, For the observation time The location of the mobile station, For the observation time The location of the mobile station.

[0161] By comparing the results of the current mobile station and dynamic reference equipment with the relative results of the previous moment, the relative positioning information at the current moment can be obtained.

[0162] The adaptive optics fusion system consists of four optical detectors, one optical information processing device, and a ground optical beacon.

[0163] As the main control unit in the adaptive optics fusion system, the optical information processing equipment is responsible for controlling the imaging of the optical detector, collecting all optical positioning data, comprehensively filtering positioning information according to availability evaluation criteria, and calculating relative positioning information after coordinate transformation.

[0164] Four optical detectors are evenly arranged. Considering the imaging and positioning accuracy of the optical beacon by detectors at different distances, each optical detector includes a large field-of-view camera and a small field-of-view camera. The large field-of-view camera has a focal length of 12mm and a vertical and horizontal field of view of 56.1°, while the small field-of-view camera has a focal length of 35mm and a vertical and horizontal field of view of 20.7°. The installation method and field-of-view distribution of the optical detectors are shown in the attached figure. Figure 5 Appendix Figure 6 As shown.

[0165] The optical beacons are powered by independent power supplies. Considering the beacon's observability at extreme distances, resistance to stray solar light, water vapor penetration, and supplier factors, a power of 200W was selected for each beacon, with a center wavelength of 850nm. The number and layout of the beacons on the moving reference equipment needed to balance calculation accuracy and the distinguishability of each beacon; therefore, 57 beacons were selected, arranged in a three-dimensional configuration. Eleven optical beacons were installed on the deck, and 46 were installed on the top of the deck pillar supports. The beacons installed on the deck pillar supports were spaced 5m apart, and the beacons installed on the deck were spaced 10m apart. To increase the distinguishability of features, the distance at corner points was increased. The relative positions of all beacons are known, and the beacons are distinguished by their arrangement. The distribution of the optical beacons is shown in the attached figure. Figure 6 Appendix Figure 7 As shown.

[0166] Although the present invention has been described in detail through the preferred embodiments above, it should be understood that the above description should not be considered as a limitation of the present invention. Various modifications and substitutions to the present invention will be apparent to those skilled in the art after reading the above description. Therefore, the scope of protection of the present invention should be defined by the appended claims.

[0167] The contents not described in detail in this specification are common knowledge to those skilled in the art.

Claims

1. A recovery positioning and measurement system based on combined positioning using dynamic differential and optical measurements, characterized in that, include: BeiDou differential positioning equipment, optical fusion systems, data integration equipment, rocket systems, data transmission equipment, data transmission antennas, navigation antennas, ground data transmission equipment, differential antennas, and BeiDou reference equipment; among which, The BeiDou differential positioning equipment performs real-time self-positioning measurements based on the BeiDou global navigation system through the navigation antenna, and outputs the absolute positioning results of the rocket system; it performs pseudorange differential and carrier phase differential relative positioning by collecting BeiDou satellite reference information through the differential antenna and the dynamic reference recovery platform self-positioning information sent by the rocket system, and obtains the satellite relative positioning results; the absolute positioning results and the satellite relative positioning results are sent to the data integration equipment. The optical fusion system collects optical beacon information, outputs optical relative positioning results, and sends them to the data integration equipment. The data integration equipment obtains a comprehensive relative positioning result based on the satellite relative positioning result output by the Beidou differential positioning equipment and the optical relative positioning result sent by the optical fusion system, and outputs it to the rocket system; it also forwards the absolute positioning result to the rocket system. The rocket system receives and demodulates information sent by the ground data transmission equipment through data transmission devices and antennas, extracts the self-positioning information of the dynamic reference recovery platform, and sends it to the Beidou differential positioning equipment; it then controls the rocket based on the absolute positioning results and the comprehensive relative positioning results. The optical fusion system includes several optical detectors, optical information processing equipment, and several optical beacons; wherein, The optical detector captures the signal of the optical beacon in real time during the rocket recovery and landing phase, and transmits the optical beacon to the optical information processing equipment in real time. The optical information processing equipment performs image matching on the optical beacon and uses a pose calculation algorithm to output the optical relative positioning result, which is then sent to the data integration equipment.

2. The recovery positioning and measurement system based on combined positioning of dynamic differential and optical measurement according to claim 1, characterized in that, The satellite relative positioning results are as follows: in, and These represent adjacent observation times during the rocket's motion; y represents the PDOT observation model; superscript , These represent satellite numbers respectively; These are inter-satellite differential carrier phase observations; This represents the corresponding inter-satellite differential geometric distance. At the speed of light, The satellite clock bias is calculated from the broadcast ephemeris parameters; For the observation time The position of the rocket, For the observation time The position of the rocket; This represents the position increment of the mobile station at adjacent time points; This is the weight matrix for the inter-satellite differential carrier phase; This is the line-of-sight matrix.

3. The recovery positioning and measurement system based on combined positioning of dynamic differential and optical measurement according to claim 2, characterized in that, The gaze matrix is ​​specifically as follows: in, For the line-of-sight matrix, Let i be the time variable, i = 1, 2, ..., n, where n is the number of observed satellites.

4. The recovery positioning and measurement system based on combined positioning of dynamic differential and optical measurement according to claim 1, characterized in that, The comprehensive relative positioning result is obtained by combining the satellite relative positioning result output by the BeiDou differential positioning device and the optical relative positioning result sent by the optical fusion system, specifically as follows: Satellite relative positioning results include carrier phase differential satellite relative positioning results and pseudorange differential satellite relative positioning results; The priorities of the relative positioning results of carrier phase differential satellite, optical relative positioning results, pseudorange differential satellite relative positioning results, and absolute positioning results of rocket system are determined sequentially as Y1, Y2, Y3, and Y4, respectively; where Y1 > Y2 > Y3 > Y4. When one or more positioning results are available, including carrier phase differential satellite relative positioning results, optical relative positioning results, pseudorange differential satellite relative positioning results, and rocket system absolute positioning results, they are sorted according to priority, and the positioning result corresponding to the highest priority is output as the comprehensive relative positioning result.

5. A recovery positioning and measurement system based on combined positioning of dynamic differential and optical measurement according to claim 4, characterized in that, The optical relative positioning result is as follows: in, The image shows the optical relative positioning result of the rocket at time t, where N is the total number of cameras and n is the total number of beacons observed by each camera at time t. for and The linear equation, Let t be the slant range between camera k and beacon i, and t be the positioning time. Let be the measured straight-line distance between beacon i and the beacon center point. Let be the straight-line distance between beacon i and the center point of the beacon in the image captured by camera k at time t. Number the camera This is the beacon number.

6. A recovery positioning and measurement system based on combined positioning of dynamic differential and optical measurement according to claim 4, characterized in that, Each optical detector includes a large field-of-view camera and a small field-of-view camera; the large field-of-view camera has a focal length of 10~12mm and a vertical and horizontal field of view of 45°~56.1°; the small field-of-view camera has a focal length of 20~35mm and a vertical and horizontal field of view of 15°~20.7°.

7. A recovery positioning and measurement system based on combined positioning of dynamic differential and optical measurement according to claim 4, characterized in that, Each optical beacon is powered by an independent power source.

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