61 results about "ECEF" patented technology

The invention discloses an airborne SAR high-resolution tomography method. The method comprises the following steps: acquiring a two-dimensional SAR image; registering the two-dimensional SAR image toobtain a registered two-dimensional SAR image; performing phase error correction on the registered two-dimensional SAR image to obtain a two-dimensional SAR image after phase correction; obtaining atarget pixel point and a coordinate of the target pixel point in a geocentric earth-fixed coordinate system from the two-dimensional SAR image after phase correction; constructing an imaging grid in the elevation direction according to the target pixel points and the coordinates; finding out homonymous pixel points from the two-dimensional SAR image after phase correction according to the imaginggrid in the elevation direction and the target pixel points; and performing focusing imaging according to the target pixel points and the homonymous pixel points to obtain a three-dimensional SAR image. According to the invention, tomography is carried out on different navigations, so that the problem of serious deterioration of elevation direction sidelobes when vertical effective baselines are distributed unevenly is solved, and the defect of inaccurate declination during elevation direction focusing is also avoided, so that high-resolution tomography is realized.

The invention discloses a cooperative target and non-cooperative target coexistence alternate Kalman space registering method, aims to provide an alternate Kalman space registering method which is notinfluenced by Earth curvature and has high precision of estimation of sensor system deviation. According to the method, under an earth centered earth fixed coordinate system, filtering initial valuesare assigned to measurement system deviation vectors and filtering estimation covariances of two sensors arranged on two moving platforms; a space registering measurement model is established, including constructing a cooperative target which can be observed by only one sensor and a measurement equation which can be simultaneously observed by the two sensors, constructing a non-cooperation targetand a measurement equation which can be simultaneously observed by the two sensors; according to the measurement equation, alternate Kalman filtering of the information based on the cooperative target and the information based on the non-cooperative target is carried out continuously till deviation estimates of the sensor measurement system are acquired, the deviation estimates are further utilized to compensate sensor measurement data, and the whole space registering process is accomplished.

The invention provides a laser plumbing method and system taking vertical deviation correction into account. The laser plumbing method comprises the following steps: after laser plumbing is completed, testing a ground coordinate of a laser spot center on a laser target in an earth-centered fixed coordinate system by using a GNSS method; acquiring corresponding vertical deviation according to the longitude and latitude of the laser spot center; calculating the altitude difference of the laser spot center on the laser target to a test point; calculating a coordinate modification amount in the earth-centered fixed coordinate system; calculating the coordinate modification amount of the laser spot center in an engineering coordinate system; finally acquiring accurate laser plumbing result. As the influence of vertical deviation is taken into full account, coordinate transmission error in conventional laser plumbing process can be effectively eliminated. The laser plumbing method is high in precision, good in reliability, easy to implement, relatively good in engineering practicability, great in engineering significance for construction of high-rise buildings, and great in market value.

The invention provides an air ground-combined intertidal zone integrated mapping method. After the original data are acquired and downloaded, spatial-temporal fusion of point cloud is carried out, andconversion from an instrument coordinate system to an earth-centered earth-fixed coordinate system is completed; and through acquiring point, line, plane and other geometric characteristics among single beam point cloud and laser scanner point cloud data and laser scanner point cloud and airborne laser detection and measurement system point cloud data, a corresponding relationship is established,and a rotation matrix and a translation amount are solved for point cloud matching. The method integrates the airborne laser detection and measurement system and a towing measurement system, underwater topography and water topography data in the intertidal zone can be acquired, the intertidal zone topography measurement problem can be solved, the two can perfectly cover measurement blind areas, and intertidal zone integrated and seamless measurement can be realized.

The present invention relates to the technical field of spaceborne synthetic aperture radar signal processing and provides a method for carrying out short arc orbit refinement by using GEOSAR (Geosynchronous Synthetic Aperture Radar) phase calibration information. The method comprises the steps of (1) obtaining the phase calibration information in an image working period through a GEOSAR phase calibration system, (2) establishing the orbit refinement problem model comprising a nonlinear motion model and a nonlinear observation model by utilizing the phase calibration information by using an earth-centered earth-fixed coordinate system and a satellite body coordinate system, and (3) using a cubature Kalman filtering method to carry out the short arc orbit refinement of the imaging working period. According to the method provided by the invention, the phase calibration information is utilized rationally, and the orbit accuracy of the GEOSAR during the imaging working period is improved in a targeted way.

The present invention discloses an angle measurement information-based multi-target identity identification method. The method comprises the steps of targeting all targets observed by all observationstations to identity recognition, wherein the identity identification for two targets observed by two observation stations is as follows: establishing a target angle measurement model; calculating theordinates of observation stations in an earth-centered and earth-fixed coordinate system; calculating unit vectors for the angle measurement lines of two targets; calculating the length of a common vertical line between the angle measurement lines of the two targets; calculating a detection threshold for checking the test statistics; and conducting the identity identification for two targets. The method is small in calculation amount and high in accuracy. The high identification accuracy is realized in a complex environment based on the method.

The invention discloses a ship-borne integrated navigation positioning method which comprises the steps of: firstly, acquiring a navigation message in a visible satellite signal; according to the navigation message, acquiring a pseudo-range between a visible satellite and a ship-borne receiver and spatial position coordinates of the visible satellite; acquiring a heading of a ship, and acquiring afirst relation function of the heading and an ECEF (Earth Centered Earth Fixed) coordinate vector; according to the spatial position coordinates of the visible satellite, emission time of the satellite signal and receiving time of the satellite signal, acquiring a pseudo-range observation equation; acquiring a second relation function of ECEF coordinates and geodetic coordinates; and according tothe first relation function, the observation equation, the second relation function and a matrix equation of a Newton iteration method, calculating current position coordinates of the ship by utilizing the Newton iteration method. According to the embodiment of the invention, a real-time position and speed of the ship are accurately and stably output, and in a case that the number of satellites is not smaller than 2, positioning calculation can be directly carried out, so that convenience of calculation is improved.

The invention provides a high maneuvering target tracking method and system based on LS and NEU-ECEF space-time registration, and belongs to the technical field of communication. The time is registered by using an improved least squares (LS) virtual fusion method, and it is not required that a ratio of sampling periods is an integer; and then, for a coordinate system conversion relationship of space registration, an algebraic operation of an original matrix is converted into a geometric operation to improve the operation efficiency while reducing the operation cost. In addition, an IMM algorithm is designed as two motion models and is combined with an MSPDAF algorithm to form a high maneuvering target applicable to tracking different dimensions. By adopting the high maneuvering target tracking method and system provided by the invention, the problem that the operation cost is large when the data size is too large in the prior art is solved.

The invention provides a pseudo range difference single-star high-dynamic positioning method in inertial navigation assistance, wherein the method comprises the steps of establishing a positioning equation by means of pseudo ranges generated by a single star at three time points and an alleviator output at a first time point; obtaining coordinate change amounts of a positioning target at a second time point, a third time point and the first time point in an earth-centered earth-fixed coordinate system by means of an inertial navigation system; substituting the coordinate change amounts into the positioning equation and solving through a least square method; establishing a state spatial model of a target dynamic process, constructing a state equation and a measuring equation which are related with Kalman filtering; using a least square result as an initial value of a Kalman filtering algorithm, and obtaining more accurate and smoother position information by means of continuous updating of a Kalman filter. According to the pseudo range difference single-star high dynamic positioning method, a single-star high-dynamic positioning algorithm model in inertial navigation assistance is established and the Kalman filtering algorithm is utilized, thereby settling a problem of positioning precision reduction caused by high dynamic characteristic of the target in single-star positioning, and improving positioning precision and precision maintainability in performing single-star positioning on the high-dynamic target.

The invention provides a grid inertial navigation method without longitude updating in a polar region. The method uses a grid coordinate system as a navigation coordinate system, the position of a carrier is represented by the position coordinates in an earth centered earth fixed coordinate system, an inertial navigation method with longitude positioning information completely not participating innavigation updating is put forward, the phenomenon that longitude error amplification caused by convergence of the longitude in the polar region results in error amplification to the inertial navigation system can be effectively eliminated, and the purpose of autonomous navigation in the polar region in the case of real-time, continuous and long voyage is achieved. The method solves the positioning error amplification caused by longitude error amplification and can also effectively avoid the influences of the longitude error amplification on the navigation performance of the inertial navigation system and can better guarantee the performance of the navigation system.

The invention discloses a realistic simulation method for satellite signals. The method comprises the following steps of radio frequency interference simulation, environment noise simulation, ionizedlayer error simulation, troposphere error simulation and error introduction simulation calculation. The method has the advantages that errors and interference of a satellite propagation process are divided into radio frequency interference, environmental noise, ionized layer errors and troposphere errors through the method, and the errors and the interference are simulated through a mathematical method and finally introduced into satellite propagation simulation calculation, so that the propagation simulation process of the satellite signals is more consistent with real situations; satellite position and speed are calculated through an earth-centered earth-fixed coordinate system, and different earth-centered earth-fixed coordinates are adopted according to different satellite types so that different satellites can use more targeted mathematical models to obtain more real simulation results.

The invention discloses an imaging method for a lunar based optical sensor. The imaging method comprises the following steps: (1) setting an optical sensor on moon; (2) confirming an imaging moment and respectively acquiring the positions of moon centroid and sun centroid under a geocentric inertial coordinate system at the imaging moment on the basis of the ephemeris data; (3) converting the positions under the geocentric inertial coordinate system into the positions under a geocentric fixed coordinate system; (4) converting the position of an observation point i on the earth under a WGS84 coordinate system into the position under the geocentric fixed coordinate system; (5) establishing a horizontal coordinate system by taking the observation point i on the earth as an original point andcalculating the positions of moon centroid and sun centroid under the horizontal coordinate system; (6) calculating a moon elevating angle and a sun elevating angle of the observation point i on the earth under the horizontal coordinate system; (7) extracting the moon elevating angle and the sun elevating angle while taking an area more than 0 as a lunar disc type observation imaging area. According to the method, the large-scale instant image and the global image in slow change of scale can be observed.

The invention relates to a polar region inertial navigation method based on a virtual ball normal vector model. The method comprises steps of initial navigation parameters being bound, and the real-time data information from an IMU inertial measurement unit and an altimeter being received; establishing a virtual ball normal vector model, and completing quaternion-based position representation andnavigation parameter conversion; establishing a differential equation based on the position, speed and attitude of the virtual ball normal vector model under the earth-centered earth-fixed coordinatesystem, and completing the calculation of navigation parameters according to the data information received in real time; and converting the navigation parameters under the earth-centered earth-fixed coordinate system into required navigation parameters under the coordinate system and outputting the required navigation parameters. The quadruple position representation method has global applicability, and avoids complex switching between a polar region and a non-polar region in a traditional scheme. The method only relates to accurate curvature radius calculation of the meridian circle and the mortise unitary circle in the reference ellipsoid model, an error problem caused by approximate curvature radius calculation under the reference ellipsoid model in a traditional method is avoided, andcalculation precision is improved.

The invention discloses a positioning method based on pseudo-ranges and linear vectors. The method includes: based on the road currently operated by the carrier, reading the topological structure, direction vector, road length, Data such as electronic elevation. Obtain the pseudo-range information of the satellite through the satellite navigation unit; extract the linear vector constraint equation of the current road in the ECEF coordinate system according to the topological information of the carrier's operating road; form the distance equation between two points in space according to the satellite pseudo-range; use the least square method Or the Kalman filter algorithm for position calculation. The present invention also provides a device for realizing the above method, which can effectively solve the positioning problem in the environment where satellite signals are blocked, and expand the positioning coverage of satellite navigation.

The invention discloses a double-base-station three-dimensional passive positioning method considering the curvature of the earth. The method comprises the following steps of firstly establishing a motion equation of a target and an external radiation source under an earth-centered earth-fixed coordinate system (ECEF) under the condition of considering the curvature of the earth, and then establishing a likelihood function according to measured double-base-station distance and angle information, solving an extreme value of the likelihood function through a genetic algorithm, and serving the extreme value as an initial motion state of the target. In addition, considering that the calculation time of the genetic algorithm is increased along with the increase of the data volume, the likelihood function is established by only selecting measurement values of the first fifteen moments in order to give consideration to requirements of real-time performance and accuracy; after the genetic algorithm obtains a target initial state by solving a solution of the likelihood function, the probability data association algorithm (PDA) is combined with the extended Kalman filter (EKF) to predict andupdate a target state at the later moment.

The invention discloses an A-INS precision measurement piecewise linear fitting method aiming at track irregularity inspection. The A-INS precision measurement piecewise linear fitting method comprises the following steps: (S100) allowing an A-INS system or a track inspection trolley to move forward along tracks to obtain a position and attitude determination result in an earth-centered earth-fixed (ECEF) coordinate system and converting and projecting the position and attitude determination result to plane coordinates and an elevation in an engineering coordinate system; (S200) segmenting thetracks from a starting mileage point to obtain piecewise straight line segments with a length of 0.625 meter, and obtaining a plane coordinate fitting straight line equation, an elevation fitting straight line equation and an attitude fitting straight line equation of each piecewise straight line segment by linear fitting; (S300) obtaining plane coordinates, the elevation, and attitude angles ofa to-be-solved point by virtue of the plane coordinate fitting straight line equation, the elevation fitting straight line equation and the attitude fitting straight line equation so as to calculate track irregularity parameters. The A-INS precision measurement piecewise linear fitting method aiming at the track irregularity inspection can fully utilize high-sampling-rate data of a GNSS/INS system, and the data utilization rate is high. Although the calculation is simple, the precision and reliability of A-INS rail precision measurement can be ensured.

The invention discloses a ground circular area satellite transit rapid forecasting method based on a geocentric angle. The method comprises the following steps: constructing a satellite load visibility geometric model under an earth-centered earth-fixed coordinate system based on the geocentric angle; calculating a geocentric angle corresponding to the radius of the ground circular area according to the geometric model; calculating a geocentric angle corresponding to a satellite cone load view field according to the geometric model and the satellite parameters; calculating an included angle between the circle center position and the geocenter connecting line of the ground circular area corresponding to different time points and the mass center and the geocenter connecting line of the satellite; and judging the load visibility of the satellite to the ground circular area, and if the load visibility is met, outputting a corresponding time point set. According to the method, the geocentric angle is utilized to construct the satellite load visibility geometric model, the visibility window time period of the satellite to the ground circular target area can be rapidly calculated through the geometric relationship, rapid forecasting of satellite transit is achieved, calculation is little, and the calculation speed is high; and specific load parameters of the satellite do not need to be obtained, and the method is suitable for practical use.

The invention discloses an initial coarse alignment method used for navigation of unmanned underwater vehicles at polar regions. The initial coarse alignment method used for navigation of unmanned underwater vehicles at polar regions comprises following steps: the initial alignment moment, and direction cosine matrix C<G><e> from earth centered earth fixed e to grid coordinate system G are determined based on the longitude and latitude at polar regions; direction cosine matrix C<G> between an inertial coordinate system and the earth centered earth fixed is determined based on time intervaldelta t; direction cosine matrix C<b<0>> from vector coordinate system b to vector coordinate system b<0> formed via fixed connection of the initial movement with inertial coordinate system is determined based on gyroscope output in a serial inertial navigation system; direction cosine matrix C<b<0>> from the vector coordinate system b<0> formed via fixed connection of the initial movement with inertial coordinate system to inertial coordinate system i is determined; direction cosine matrix C<G> from the vector coordinate system b to grid coordinate system G is determined; calculatingand extracting of phi x, phi y, phi z, delta phi x, delta phi y, and delta phi z obtained via initial coarse alignment are carried out. The initial coarse alignment method is capable of realizing coarse alignment of unmanned underwater vehicles at polar regions effectively, and the precision is better than that of a conventional coarse alignment method at polar regions.