Recovery positioning measurement system based on combined positioning of dynamic differential and optical measurement

Abstract

The invention discloses a recovery positioning measurement system based on joint positioning of dynamic-dynamic difference and optical measurement, and the system comprises a Beidou differential positioning device which carries out the self-positioning measurement based on a Beidou global navigation system in real time through a navigation antenna, and outputs an absolute positioning result of a rocket system; pseudo-range differential and carrier phase differential relative positioning is carried out through Beidou satellite reference information collected by a differential antenna and dynamic reference recovery platform self-positioning information sent by a rocket system, and a satellite relative positioning result is obtained; the optical fusion system is used for acquiring optical beacon information and outputting an optical relative positioning result; the data comprehensive equipment outputs a comprehensive relative positioning result to the rocket system; the rocket system receives and demodulates the information sent by the ground data transmission equipment through the data transmission equipment and the data transmission antenna, and analyzes the self-positioning information of the dynamic reference recovery platform; and performing rocket control according to the absolute positioning result and the comprehensive relative positioning result. According to the invention, the positioning precision is improved.

Description

Technical Field

[0001] The invention relates to a recovery positioning measurement system based on dynamic-dynamic differential and optical measurement joint positioning, belonging to the technical field of returnable carrier rocket navigation. Background Art

[0002] Launch vehicles are the main means for humans to explore space and become a space power. Compared with "disposable launch vehicles", after launching from the ground and completing the scheduled mission, the launch vehicle returns and lands. After maintenance and fuel filling, it can perform the launch mission again, which is more economical and environmentally friendly. In the vertical return and reuse mission of the returnable launch vehicle, the first stage of the rocket has the flight characteristics of large airspace, high dynamics, and high Mach. The conventional satellite / inertial combined navigation system will face the problems of rocket body disturbance, continuous reversal, blackout and other factors in the return phase of the rocket. In addition, the recovery process and the ballistic characteristics of the rocket recovery stage bring difficulties to the recovery of the rocket.

[0003] Dynamic relative positioning relative to a mobile reference station is referred to as dynamic-to-dynamic positioning, which 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 proximity, carrier collision avoidance, automatic driving, etc. In these occasions, traditional positioning methods (such as radar / laser ranging) are not accurate or have strict restrictions and cannot fully meet the requirements.

[0004] On the basis of traditional satellite positioning, based on the Beidou satellite navigation system, pseudo-range differential algorithm and carrier phase differential algorithm are used to ensure the real-time and accuracy of the recovery positioning results, and optical fusion technology is used to improve the reliability of recovery positioning. Compared with traditional positioning technology, the recovery positioning measurement technology based on dynamic differential + optical measurement joint positioning adopts redundant positioning architecture, relative positioning technology based on pseudo-range differential and carrier phase differential, dynamic position estimation method, and adaptive optical fusion technology, realizing a strong real-time, high-precision, and highly reliable recovery positioning system design, providing accurate and reliable absolute navigation and relative navigation information for the recovery of the rocket on the moving platform, so as to improve the navigation accuracy of the rocket's first stage, reduce the landing point dispersion range of the rocket's sub-stage under various deviation conditions and disturbances, and lay the foundation for realizing the fixed-point recovery and reuse of the rocket's sub-stage.

[0005] At present, foreign recovery positioning measurement uses traditional GPS positioning, which has low measurement accuracy. The accuracy of the recovery landing phase is guaranteed by inertial navigation devices, which is only applicable to medium and lower weight rockets. Domestic recovery positioning is a static benchmark, and the precise position of the landing target is known. The accuracy requirements can be met by using visual fusion or conventional differential algorithms. It is not suitable for the high-precision, high-dynamic, 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 deficiencies of the prior art, to provide a recovery positioning measurement system based on dynamic differential and optical measurement combined positioning, and to improve the recovery positioning high precision.

[0007] The technical solution of the present invention is:

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

[0009] Beidou differential positioning equipment uses the navigation antenna to perform real-time self-positioning measurements based on the Beidou global navigation system and output the absolute positioning results of the rocket system. It uses the Beidou satellite reference information collected by the differential antenna and the dynamic reference recovery platform self-positioning information sent by the rocket system to perform pseudo-range differential and carrier phase differential relative positioning to obtain satellite relative positioning results. It sends the absolute positioning results and satellite relative positioning results 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 device;

[0011] The data integration equipment obtains the 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; the absolute positioning result is forwarded to the rocket system;

[0012] The rocket system receives and demodulates the information sent by the ground data transmission equipment through the data transmission equipment and data transmission antenna, parses the self-positioning information of the dynamic reference recovery platform, and sends it to the Beidou differential positioning equipment; the rocket is controlled 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:

[0014] X(t1)=X(t0)+dX

[0015] dX=(A T PA) -1 A T Py

[0016]

[0017] Wherein, t0 and t1 are the adjacent observation times during the rocket motion; y is the PDOT observation model; superscripts i and j represent the satellite numbers respectively; Φ is the inter-satellite differential carrier phase observation value; ρ is the corresponding inter-satellite differential geometric distance, c is the speed of light, δt is the satellite clock error, which is calculated from the broadcast ephemeris parameters; X(t0) is the rocket position at the observation time t0, and X(t1) is the rocket position at the observation time t1; dX is the mobile station position increment at adjacent times; P is the weight matrix of the inter-satellite differential carrier phase; A is the line of sight matrix.

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

[0019]

[0020] k i1 =x 3 ,k i2 =x 2 ,k i3 =x,k i4 =1

[0021] Among them, A is the line of sight matrix and x is the time variable.

[0022] Further, in the above system, the satellite relative positioning result output by the Beidou differential positioning device and the optical relative positioning result sent by the optical fusion system are used to obtain a comprehensive relative positioning result, which is specifically:

[0023] The satellite relative positioning results include the carrier phase differential satellite relative positioning results and the pseudo-range differential satellite relative positioning results;

[0024] The priorities of the carrier phase differential satellite relative positioning result, the optical relative positioning result, the pseudo-range differential satellite relative positioning result and the absolute positioning result of the rocket system are determined in sequence as Y1, Y2, Y3 and Y4 respectively; among which, Y1>Y2>Y3>Y4;

[0025] When one or more positioning results including carrier phase differential satellite relative positioning results, optical relative positioning results, pseudo-range differential satellite relative positioning results and absolute positioning results of the rocket system appear, 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 a number of optical detectors, optical information processing equipment and a number of 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 device performs image matching on the optical beacon and adopts a posture solving algorithm to output the optical relative positioning result and send it to the data integration device.

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

[0030]

[0031] L (k,i) (R (k,i) ,t)=C 2(k,i) / C 1(k,i)

[0032] Where L is the optical relative positioning result of the rocket at time t, N is the total number of cameras, n is the total number of beacons observed by each camera at time t, and L (k,i) (R (k,i ),t) is R (k,i) and t, R (k,i) is the slant distance between camera k and beacon i, t is the positioning time, C 2(k,i) is the measured value of the straight-line distance between beacon i and the beacon center point, C 1(k,i) is the straight-line distance between beacon i and the center point of the beacon in the image taken by camera k at time t, k is the camera number, and i 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 to 12 mm, and the vertical and horizontal field of view angles are both 45° to 56.1°; the small field of view camera has a focal length of 20 to 35 mm, and the vertical and horizontal field of view angles are both 15° to 20.7°.

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

[0035] The beneficial effects of the present invention and the prior art are:

[0036] (1) The present invention constructs a positioning architecture with redundant features, utilizes pseudo-range differential and carrier phase differential relative positioning technology, a dynamic position estimation method, and adaptive optical fusion technology, and realizes the design of a strong real-time, high-precision, and highly reliable recovery positioning system.

[0037] (2) The present invention constructs a differential relative positioning system architecture based on the Beidou satellite navigation system with redundant characteristics, and selects a method that integrates two relative positioning technologies, namely pseudo-range differential and carrier phase differential. It not only solves the problem of unstable positioning caused by factors such as large airspace, high dynamics, and high Mach flight characteristics of the first stage of the recovery and landing rocket, as well as factors such as rocket body disturbance, continuous reversal, blackout, total reflection from the sea surface, and flame flipping, but also solves the problem of high-precision recovery positioning.

[0038] (3) The present invention constructs a dynamic position estimation method, adopts a real-time dynamic recursive strategy, and combines the time sliding window polynomial fitting method to perform short-time recursive processing on the dynamic reference device and the dynamic mobile device respectively, and estimates the relative position information of the current dynamic reference device and the dynamic mobile device based on the data information at the previous moment, thereby achieving strong real-time recovery positioning.

[0039] (4) The present invention adopts an adaptive optical fusion technology, which realizes high-precision positioning of the recovery landing stage near the platform area by deploying a four-diversity optical detector and an optical information processing device on the recovery return equipment and an optical beacon on the recovery platform, effectively solving the problem of unstable positioning caused by interference factors such as flame flipping, water vapor ionization, and total reflection of seawater in the recovery positioning measurement. 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 for algorithm fusion, solving the problem of high-precision recovery positioning at sea.

[0040] (5) The present invention adopts the recovery positioning measurement technology based on dynamic differential + optical measurement joint positioning, which realizes the real-time recovery positioning measurement accuracy of less than 1 meter in the offshore recovery scenario where the recovery mobile equipment has a motion acceleration of 5g / s, an acceleration of 2g / s2, and a relative distance of 3 kilometers. BRIEF DESCRIPTION OF THE DRAWINGS

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

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

[0043] Figure 3 It is a flow chart of the time sliding window polynomial moving reference position prediction algorithm of the present invention;

[0044] Figure 4 It is a block diagram of the composition of the adaptive optical fusion system of the present invention;

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

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

[0047] Figure 7 It is a coordinate diagram of the optical beacon layout of the present invention. DETAILED DESCRIPTION

[0048] The present invention is further described in detail below in conjunction with the accompanying drawings and specific implementation methods.

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

[0050] Beidou differential positioning equipment uses the navigation antenna to perform real-time self-positioning measurements based on the Beidou global navigation system and output the absolute positioning results of the rocket system. It uses the Beidou satellite reference information collected by the differential antenna and the dynamic reference recovery platform self-positioning information sent by the rocket system to perform pseudo-range differential and carrier phase differential relative positioning to obtain satellite relative positioning results. It sends the absolute positioning results and satellite relative positioning results 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 device;

[0052] The data integration equipment obtains the 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; the absolute positioning result is forwarded to the rocket system;

[0053] The rocket system receives and demodulates the information sent by the ground data transmission equipment through the data transmission equipment and data transmission antenna, parses the self-positioning information of the dynamic reference recovery platform, and sends it to the Beidou differential positioning equipment; the rocket is controlled based on the absolute positioning results and the comprehensive relative positioning results.

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

[0055] X(t1)=X(t0)+dX

[0056] dX=(A T PA) -1 A T Py

[0057]

[0058] Wherein, t0 and t1 are the adjacent observation times during the rocket motion; y is the PDOT observation model; superscripts i and j represent the satellite numbers respectively; Φ is the inter-satellite differential carrier phase observation value; ρ is the corresponding inter-satellite differential geometric distance, c is the speed of light, δt is the satellite clock error, which is calculated from the broadcast ephemeris parameters; X(t0) is the rocket position at the observation time t0, and X(t1) is the rocket position at the observation time t1; dX is the mobile station position increment at adjacent times; P is the weight matrix of the inter-satellite differential carrier phase; A is the line of sight matrix.

[0059] Preferably, the sight line matrix is ​​specifically:

[0060]

[0061] k i1 =x 3 ,k i2 =x 2 ,k i3 =x,k i4 =1

[0062] Among them, A is the line of sight matrix and x is the time variable.

[0063] Preferably, a comprehensive relative positioning result is obtained according to 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:

[0064] The satellite relative positioning results include the carrier phase differential satellite relative positioning results and the pseudo-range differential satellite relative positioning results;

[0065] The priorities of the carrier phase differential satellite relative positioning result, the optical relative positioning result, the pseudo-range differential satellite relative positioning result and the absolute positioning result of the rocket system are determined in sequence as Y1, Y2, Y3 and Y4 respectively; among which, Y1>Y2>Y3>Y4;

[0066] When one or more positioning results including carrier phase differential satellite relative positioning results, optical relative positioning results, pseudo-range differential satellite relative positioning results and absolute positioning results of the rocket system appear, 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 device performs image matching on the optical beacon and adopts a posture solving algorithm to output the optical relative positioning result and send it to the data integration device.

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

[0071]

[0072] L (k,i) (R (k,i) ,t)=C 2(k,i) / C 1(k,i)

[0073] Where L is the optical relative positioning result of the rocket at time t, N is the total number of cameras, n is the total number of beacons observed by each camera at time t, and L (k,i) (R (k,i) ,t) is R (k,i) and t, R (k,i) is the slant distance between camera k and beacon i, t is the positioning time, C 2(k,i) is the measured value of the straight-line distance between beacon i and the beacon center point, C 1(k,i) is the straight-line distance between beacon i and the center point of the beacon in the image taken by camera k at time t, k is the camera number, and i 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 to 12 mm, and the vertical and horizontal field of view angles are both 45° to 56.1°; the small field of view camera has a focal length of 20 to 35 mm, and the vertical and horizontal field of view angles are both 15° to 20.7°.

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

[0076] Example

[0077] like Figure 1 As shown, the recovery positioning and measurement system based on dynamic differential + optical measurement combined positioning consists of the following: data integration equipment, optical information processing equipment, optical detectors, 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 of recovery positioning measurement based on dynamic differential + optical measurement joint positioning is as follows:

[0079] In the dynamic-to-dynamic recovery positioning measurement system, the Beidou reference information on the dynamic reference recovery platform is measured in real time based on the Beidou global navigation system for self-positioning. The Beidou reference information is transmitted to the outside in the form of wireless signals through the digital transmission channel via the ground data transmission equipment and the ground data transmission antenna. The dynamic rocket receives and demodulates the wireless information uploaded from the ground through the digital transmission antenna and data transmission equipment, parses the self-positioning information of the dynamic reference recovery platform, and transmits it to the Beidou differential positioning equipment.

[0080] Beidou differential positioning equipment uses navigation antennas to perform real-time self-positioning measurements based on the Beidou global navigation system and output absolute positioning results. At the same time, Beidou satellite reference information is collected using differential antennas. The Beidou satellite reference information collected by itself and the Beidou satellite reference information collected by the dynamic reference recovery platform are relatively positioned by pseudo-range difference and carrier phase difference, and combined with dynamic position estimation methods, the accuracy and real-time performance of relative positioning results are improved.

[0081] The four-diversity optical detector uses optical beacon measurement technology to capture the optical beacon signal image in real time during the rocket recovery and landing phase, extract the optical beacon image, and transmit the image information to the optical information processing device in real time. The optical information processing device performs image matching on the beacon image information and uses a posture solution algorithm to output relative positioning results.

[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. It outputs the rocket's self-positioning absolute positioning results during the rocket's ascent and recovery and return phases to assist flight, and outputs highly reliable and high-precision real-time positioning results during the recovery and landing phase for recovery positioning measurement.

[0083] Pseudorange differential positioning uses 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] Among them, ρ k represents the pseudorange observation, r k represents the true distance between the dynamic reference device and the satellite, c represents the speed of light, δt u,k represents the receiver clock error, represents the satellite clock error, dρ k represents the satellite orbit error, E k represents the correction value of the earth's rotation, I k represents the ionospheric delay error, T krepresents the tropospheric delay error, ε ρ,k represents the pseudorange observation noise and multipath error.

[0087] According to the double difference principle, in short baseline measurement, the propagation paths from the same satellite to different antennas can be considered the same, and only the observation noise and multipath error remain in the double difference observation equation. At this time, the double difference observation equation is as follows:

[0088]

[0089] When the number of common-view satellites is m, m-1 pseudo-range double-difference equations can be established for each epoch. The double-difference observation equations are linearized and the pseudo-range double-difference equations are established for different epochs t:

[0090] B Rt b t =L Rt (3)

[0091] In the formula, B Rt is the coefficient matrix of the carrier phase and pseudorange double difference equations of the tth epoch, with m-1 rows and 3 columns; b t is the three-dimensional coordinate correction value vector of the receiver at the tth epoch, with an order of 3; L Rt is a constant term vector with an order of m-1, and is the residual matrix of the pseudorange double-difference observation equation at the tth epoch.

[0092] Since there is no ambiguity problem in pseudo-range observations and the accuracy of pseudo-range observations is high, 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 the original observations that have been preprocessed, combines the observations of pseudorange and carrier phase to resolve the 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] Among them, ρ k represents the pseudorange observation, λ represents the carrier wavelength, represents the carrier phase observation value, N0 represents the initial integer ambiguity, r k represents the true distance between the dynamic reference device and the satellite, c represents the speed of light, δt u,k represents the receiver clock error, represents the satellite clock error, dρ krepresents the satellite orbit error, E k represents the correction value of the earth's rotation, I k represents the ionospheric delay error, T k represents the tropospheric delay error, ε ρ,k represents the pseudorange observation noise and multipath error, represents the carrier phase observation noise and multipath error.

[0097] According to the double difference principle, in short baseline measurement, the propagation paths from the same satellite to different antennas can be considered the same, and only the observation noise and multipath error remain in the double difference observation equation. At this time, the double difference observation equation is as follows:

[0098]

[0099] When the number of common-view satellites is m, m-1 carrier phase double-difference equations and m-1 pseudo-range double-difference equations can be established for each epoch. The double-difference observation equations are linearized, and the carrier phase double-difference and pseudo-range double-difference equations are established for different epochs t:

[0100]

[0101] B Rt b t =L Rt (9)

[0102] In the formula, B Rt is the coefficient matrix of the carrier phase and pseudorange double difference equations of the tth epoch, with m-1 rows and 3 columns; b t is the three-dimensional coordinate correction value vector of the receiver at the t-th epoch, with an order of 3; A is the ambiguity design matrix. When only the phase observation value is considered, A=E (E is the unit matrix) can be selected; a is the integer ambiguity vector of the wide-lane carrier phase, with an order of m-1. This is a constant vector that is independent of the change of epoch t. If it is assumed that the number of satellites observed at each epoch is the same, the order remains unchanged. This is acceptable in a short period of time. For convenience, this assumption will be applied; and L Rt is a constant term vector with an order of m-1, and is the residual matrix of the carrier phase double difference and pseudorange double difference observation equations at the tth epoch.

[0103] In addition to carrier phase observations, dual-frequency receivers can also obtain pseudorange observations, which do not have ambiguity problems and have high accuracy. In this way, pseudorange observations can be used to improve the strength of the positioning equation. The double difference observation equation of pseudorange and carrier phase is:

[0104]

[0105] In the formula, is the design matrix of the double-difference observation equation for the carrier phase at the t-th epoch, B Rt is the design matrix of the pseudorange double-difference observation equation for the t-th epoch, is the residual vector matrix of the phase observation vector at the tth epoch, L Rt is the residual vector matrix of the phase observation vector at the tth epoch, b t is the three-dimensional coordinate correction value vector of the receiver at the tth epoch, with an order of 3, a is the value of the double-difference carrier phase integer ambiguity, E is the unit matrix, and n is the number of epochs used to establish the current double-difference observation equation.

[0106] For multiple observations, new "observations" can be obtained by linear combination, also called virtual observations. These observations should meet at least one of the following criteria:

[0107] 1) The observation value after linear combination should be able to maintain the integer characteristic of ambiguity, so as to facilitate the initialization of ambiguity;

[0108] 2) The linearly combined observations should have an appropriate wavelength;

[0109] 3) The observation value after linear combination should be unaffected or substantially unaffected by ionospheric delay;

[0110] 4) The observations after linear combination should have smaller measurement noise.

[0111] According to the above principle, the wide-lane observation value can be constructed by using the linear combination of dual-frequency data. In this scheme, the wide-lane ambiguity value is first calculated by combining the pseudo-range observation value with the wide-lane carrier phase observation value, and the normal equation is constructed according to the above equation group:

[0112]

[0113] In the formula, and P Rt are the weight matrices of the carrier phase double difference and pseudorange double difference of the t-th epoch, respectively. The normal equation is divided into blocks according to the dotted lines in the formula, and only the ambiguity sub-blocks are calculated. The matrix decomposition is performed, and the intermediate process is omitted. The estimation formula of the wide-lane carrier phase ambiguity is directly given as follows:

[0114]

[0115] Where:

[0116]

[0117] The cofactor matrix of the real solution of wide-lane carrier phase ambiguity is:

[0118]

[0119] According to the floating-point solution of the above-mentioned carrier phase ambiguity and the corresponding covariance matrix, the LAMBDA method is used to search, that is, the real solution of the wide-lane carrier phase ambiguity and the covariance matrix of the real solution are used as the input conditions of the LAMBDA method, and the integer solution of the wide-lane carrier phase integer ambiguity is obtained after searching.

[0120] Integer solution using wide lane integer ambiguity The ambiguity is decomposed according to the relationship shown in the following formula to obtain the double difference integer ambiguity of the B1 / B3 carrier phase:

[0121]

[0122] The B1 / B3 carrier double difference observation value obtained after the 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, that is, the relative positioning result.

[0123] Dynamic Position Estimation Method

[0124] In view of the delay and link reliability, the dynamic position estimation method is adopted to perform short-term recursion on the positions of the dynamic reference device and the mobile receiving device respectively, so as to obtain real-time relative position information. Figure 4 shown.

[0125] Moving reference position estimation

[0126] High-precision differential positioning technology requires the use of information from the platform dynamic reference device and the mobile receiving device at the same time for calculation, and gives the relative positioning result at the corresponding time of the data, including two working modes: pseudo-range differential positioning (RTD) and carrier phase differential positioning (RTK). In actual use, the platform dynamic reference device collects data, and after positioning is completed, it sends the data to the mobile receiving device through the wireless link between the arrow and the ground. After the mobile receiving device receives the data sent by the platform dynamic reference device, it uses the data at the same time as the platform dynamic reference device for relative positioning processing, and outputs the relative positioning result.

[0127] Attached Figure 2 is the timing of data transmission and data processing, and T0 and T1 are the corresponding times of the data. After the platform dynamic reference device completes the navigation positioning at time T0, it sends the data to the mobile receiving device through the wireless link. The mobile receiving device receives the data of the platform dynamic reference device at time T1, and after calculation, outputs the relative positioning result at time T0 at time T2.

[0128] The time delay for a mobile receiving device to send relative positioning results mainly consists of three parts: the time it takes for the dynamic reference device to send data, the wireless link transmission time, and the calculation time of the mobile receiving device.

[0129] In the recovery scenario, strong real-time and high-precision relative positioning measurement is required. Since both the platform dynamic reference equipment and the recovered rocket are in motion, the relative positioning technology used by conventional fixed dynamic reference equipment has the following shortcomings:

[0130] The dynamic reference device is not completely static, so the coordinates of the dynamic reference device cannot be calibrated and provided to the mobile station for use;

[0131] Dynamic mobile devices can perform relative positioning processing only after receiving dynamic reference device information transmitted by wireless links. Due to the influence of wireless link transmission, there will inevitably be output data delay.

[0132] Based on the above problems, differential positioning technology can achieve high-precision relative positioning measurement. Combined with the characteristics of the dynamic reference equipment in this task, which is extremely small and only affected by the waves along with the barge, a real-time dynamic recursion strategy is proposed to perform short-term recursive processing on the dynamic reference equipment and dynamic mobile equipment respectively, and estimate the relative position information of the current dynamic reference equipment and dynamic mobile equipment based on the data information of the previous moment.

[0133] The time sliding window polynomial fitting method is used to estimate the position information of the dynamic reference device. This method predicts the target's motion state at future moments by processing a historical data sequence of the target's motion state, and continuously slides forward as the data is updated. Assuming that the target's motion is in a variable acceleration state, the function that satisfies the cubic polynomial is used for fitting, specifically:

[0134] f(x)=ax 3 +bx 2 +cx+d (15)

[0135] In formula (15), the independent variable x is the time variable with the dimension of seconds; a, b, c and d are the coefficients of the polynomial respectively.

[0136] Normalize the original time t, then

[0137]

[0138] Where Δt = t n -t1.

[0139] The least squares method is used to solve the above equation and it can be written in matrix form as follows:

[0140] Y=Ax+e (17)

[0141] In the formula,

[0142]

[0143] x is the coefficient value vector to be solved, and Y is the observed value

[0144] vector, e is the observed state error vector. k i1 =x 3 ,k i2 =x 2 ,k i3 =x,k i4 =1

[0145] Substitute the absolute position coordinates of the carrier into equation (17), find 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 attached Figure 3 shown.

[0146] Mobile station location recursion

[0147] The mobile station uses the epoch-to-epoch differential recursion method to calculate the current position information of the mobile station in combination with the positioning result of the mobile station at the previous moment.

[0148] The PDOT positioning model is used for inter-epoch differential recursion, and the receiver clock error and hardware delay parameters can be eliminated using the inter-satellite single difference elimination strategy. When the sampling rate of the mobile receiving device is not less than 1 Hz and the carrier motion speed is limited, the inter-epoch differential can greatly weaken the impact of the slowly changing and spatially strongly correlated ionospheric and tropospheric errors. The ambiguity parameters have an invariant characteristic when there is no cycle slip in the carrier phase observation value, and can be eliminated by differencing the observation values ​​before and after. Assuming that the adjacent observation times of the mobile station are t0 and t1, the PDOT observation model can be abbreviated as

[0149]

[0150] Where, the superscripts i and j represent the satellite numbers respectively; Φ is the inter-satellite differential carrier phase observation value; ρ is the corresponding inter-satellite differential geometric distance, c is the speed of light, and δt is the satellite clock error.

[0151] The satellite clock error inter-satellite difference term δt in equation (18) is ij Calculated from the broadcast ephemeris parameters. Substitute the absolute value of the mobile station at the last moment into equation (18) as the initial value of the linearization of the observation equation, and we have

[0152] y=AdX+ε (19)

[0153] In the formula,

[0154]

[0155] A is the line of sight matrix.

[0156] According to formula (19), the least square method is used to obtain the mobile station position increment at adjacent times:

[0157] dX=(A T PA) -1 A T Py (20)

[0158] Where P is the weight matrix of the inter-satellite differential carrier phase.

[0159] According to formula (20), the position increment at adjacent times is calculated, and then combined with the relative position of the mobile station at the previous time, the relative position of the mobile station at the current time can be obtained:

[0160] X(t1)=X(t0)+dX (21)

[0161] Where X(t0) is the position of the mobile station at the observation time t0, and X(t1) is the position of the mobile station at the observation time t1.

[0162] By comparing the results of the mobile station and the dynamic reference device at the current moment with the relative results at the previous moment, the relative positioning information at the current moment can be obtained.

[0163] The adaptive optical fusion system consists of four optical detectors, one optical information processing device and a ground optical beacon.

[0164] As the main control part of the adaptive optical fusion system, the optical information processing equipment is responsible for controlling the imaging of the optical detector, collecting all optical positioning data, comprehensively screening the positioning information according to the availability evaluation criteria, and solving the relative positioning information after coordinate conversion.

[0165] The four optical detectors are evenly arranged. Considering the imaging of the optical beacon by the detectors at different distances and the positioning accuracy, each optical detector contains a large field of view camera and a small field of view camera. The focal length of the large field of view camera is 12mm, and the vertical and horizontal field of view angles are both 56.1°. The focal length of the small field of view camera is 35mm, and the vertical and horizontal field of view angles are both 20.7°. The installation method of the optical detector and the distribution of the field of view angle are shown in the attached figure. Figure 5 , Attachment Figure 6 shown.

[0166] The optical beacon is powered by an independent power supply. Taking into account the observability of the beacon at extreme distances, the ability to resist solar stray light, the ability to penetrate water vapor and supplier factors, the power of each beacon is selected to be 200W and the central wavelength is 850nm. The number and layout of beacons on the mobile reference device need to take into account the solution accuracy and the identifiability of each beacon. The number of beacons is selected to be 57, and a three-dimensional arrangement is adopted. Among them, 11 optical beacons are installed on the deck and 46 optical beacons are installed on the top of the deck column bracket. The beacons installed on the deck column bracket are spaced 5m apart, and the beacons installed on the deck are spaced 10m apart. In order to increase the distinguishability of the features, the distance at the corner points is increased. The relative position relationship of all beacons is known, and the beacons are distinguished by their arrangement. The distribution of optical beacons is shown in the attached figure. Figure 6 , Attachment Figure 7 shown.

[0167] Although the content of the present invention has been described in detail through the above preferred embodiments, it should be appreciated that the above description should not be considered as a limitation of the present invention. After reading the above content, it will be apparent to those skilled in the art that various modifications and substitutions of the present invention will occur. Therefore, the protection scope of the present invention should be limited by the appended claims.

[0168] The contents not described in detail in the specification of the present invention belong to the common knowledge of the professionals in this field.

Claims

1. A recovery positioning measurement system based on dynamic differential and optical measurement joint positioning, characterized in that: include: Beidou differential positioning equipment, optical fusion system, data integration equipment, rocket system, data transmission equipment, data transmission antenna, navigation antenna, ground data transmission equipment, differential antenna and Beidou reference equipment; among them, Beidou differential positioning equipment uses the navigation antenna to perform real-time self-positioning measurements based on the Beidou global navigation system and output the absolute positioning results of the rocket system. It uses the Beidou satellite reference information collected by the differential antenna and the dynamic reference recovery platform self-positioning information sent by the rocket system to perform pseudo-range differential and carrier phase differential relative positioning to obtain satellite relative positioning results. It sends the absolute positioning results and satellite relative positioning results 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 device; The data integration equipment obtains the 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; the absolute positioning result is forwarded to the rocket system; The rocket system receives and demodulates the information sent by the ground data transmission equipment through the data transmission equipment and data transmission antenna, parses the self-positioning information of the dynamic reference recovery platform, and sends it to the Beidou differential positioning equipment; the rocket is controlled based on the absolute positioning results and the comprehensive relative positioning results.

2. The recovery positioning measurement system based on dynamic differential and optical measurement combined positioning according to claim 1 is characterized in that: The satellite relative positioning result is specifically: X(t1)=X(t0)+dX dX=(A T PA) -1 A T Py Wherein, t0 and t1 are the adjacent observation times during the rocket motion; y is the PDOT observation model; superscripts i and j represent the satellite numbers respectively; Φ is the inter-satellite differential carrier phase observation value; ρ is the corresponding inter-satellite differential geometric distance, c is the speed of light, δt is the satellite clock error, which is calculated from the broadcast ephemeris parameters; X(t0) is the rocket position at the observation time t0, and X(t1) is the rocket position at the observation time t1; dX is the mobile station position increment at adjacent times; P is the weight matrix of the inter-satellite differential carrier phase; A is the line of sight matrix.

3. The recovery positioning measurement system based on dynamic differential and optical measurement combined positioning according to claim 2 is characterized in that: The sight line matrix is ​​specifically: k i1 =x 3 ,k i2 =x 2 ,k i3 =x,k i4 =1 Where A is the line of sight matrix, x is the time variable, i = 1, 2, ..., n, and n is the number of observed satellites.

4. The recovery positioning measurement system based on dynamic differential and optical measurement combined positioning according to claim 1 is characterized in that: The 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: The satellite relative positioning results include the carrier phase differential satellite relative positioning results and the pseudo-range differential satellite relative positioning results; The priorities of the carrier phase differential satellite relative positioning result, the optical relative positioning result, the pseudo-range differential satellite relative positioning result and the absolute positioning result of the rocket system are determined in sequence as Y1, Y2, Y3 and Y4 respectively; among which, Y1>Y2>Y3>Y4; When one or more positioning results including carrier phase differential satellite relative positioning results, optical relative positioning results, pseudo-range differential satellite relative positioning results and absolute positioning results of the rocket system appear, they are sorted according to priority, and the positioning result corresponding to the highest priority is output as the comprehensive relative positioning result.

5. The recovery positioning measurement system based on dynamic differential and optical measurement combined positioning according to claim 1 is characterized in that: The optical fusion system includes a number of optical detectors, optical information processing equipment and a number of 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 device performs image matching on the optical beacon and adopts a posture solving algorithm to output the optical relative positioning result and send it to the data integration device.

6. The recovery positioning measurement system based on dynamic differential and optical measurement combined positioning according to claim 5 is characterized in that: The optical relative positioning result is specifically: L (k,i) (R (k,i) ,t)=C 2(k,i) / C 1(k,i) Where L is the optical relative positioning result of the rocket at time t, N is the total number of cameras, n is the total number of beacons observed by each camera at time t, and L (k,i) (R (k,i) ,t) is R (k,i) and t, R (k,i) is the slant distance between camera k and beacon i, t is the positioning time, C 2(k,i) is the measured value of the straight-line distance between beacon i and the beacon center point, C 1(k,i) is the straight-line distance between beacon i and the center point of the beacon in the image taken by camera k at time t, k is the camera number, and i is the beacon number.

7. The recovery positioning measurement system based on dynamic differential and optical measurement combined positioning according to claim 5 is characterized in that: Each optical detector comprises 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 to 12 mm, and the vertical and horizontal field of view angles are both 45° to 56.1°; the small field of view camera has a focal length of 20 to 35 mm, and the vertical and horizontal field of view angles are both 15° to 20.7°.

8. The recovery positioning measurement system based on dynamic differential and optical measurement combined positioning according to claim 5 is characterized in that: Each optical beacon is powered by an independent power supply.

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