213 results about "Gravity anomaly" patented technology

The invention discloses a matching navigation method based on local gravity field approximation. The method comprises the following steps that: at first, a flight path indicated by an inertial navigation system in a period of time is acquired as an initial flight path for matching, a gravity abnormal value corresponding to the point of the flight path indicated by the inertial navigation system is acquired, grid data of a local square region are intercepted in a gravity anomaly reference graph through the flight path indicated by the inertial navigation system and a confidence interval thereof, and a function of a gravity anomaly graph of the square region is acquired; and then terrain contour matching algorithm is used for rough matching, difference pretreatment is carried out on a gravity measuring sequence, then rough matching is carried out by using the terrain contour matching algorithm, and matching results are used as an initial flight path for matching algorithm of a related extreme value; and a matching algorithm optimization interval of the related extreme value is acquired based on the rough matching results obtained through terrain contour matching and the confidence interval, an iterative random initial value is generated by an average random number and enters into BFGS for optimization, an optimal matching flight path is calculated based on optimal solution of BFGS optimization, and the original flight path is updated. The method provided by the invention enables available matching precision to be higher through construction of a local gravity field reference graph.

The invention relates to a method for determining quasigeoid models by utilizing deviation of plumb line and gravity anomaly, and aims at effectively improving the modeling precision of quasigeoid and solving the determination problem of height datum in geodetic surveying. The method comprises the following steps: by adopting the differential relation of height anomalies, computing the grid relative height anomaly difference via the deviations of plumb lines and gravity anomalies of the grids; imposing restriction through a GPS / benchmark to obtain height anomaly of grid nodes, and computing the relative height anomaly difference between adjacent nodes by utilizing the deviation of plumb line, gravity anomaly and digital height data of each node; computing the height anomaly difference of adjacent grids, carrying out adjustment computation by a parameter adjustment model and determining the quasigeoid models; selecting three million-sheet 4 DEG*6 DEG areas with deviations of plumb lines, gravity anomalies and terrain grid data to respectively computing and establishing the quasigeoid models of the three areas, and analyzing the precision. The method provided by the invention is novel, unique, high in efficiency and high in precision, and is an innovation in geodetic surveying.

The invention relates to a marine inertia-gravity integrated navigation device, which consists of a dual-ring inertial platform system, a gravity sensor, a Doppler log, a deep sounding apparatus, a digital gravity anomaly chart, an integrated navigation computer and a display terminal. The inertial measurement sensor of the dual-ring inertial platform system is a liquid floated gyroscope, a rate fiber optic gyroscope and a quartz flexible pendulous accelerometer. The device not only can be used to position and orient ocean motion carriers, but also can be used to measure marine gravity. Moreover, the device has the advantages of small size, high precision, good reliability, simple structure and easy maintenance, and has a wide scope of application in the technical field of navigation and control.

The inertial system for gravity difference measurement uses COTS nano accelerometer and a strapdown Global Navigation Satellite System (GNSS)-aided inertial measurement unit (IMU). The former has low measurement noise density, while the latter is used to analytically stabilize the platform. Stochastic modeling of the gravity anomaly is utilized (as opposed to the deterministic modeling of causes and effects) to simplify the algorithm. The algorithm aims at finding relative changes between points, as opposed to absolute values at the points, which allows for high relative precision required in many applications.

A covert tracer round has an infrared emitter of radiation mounted to its front, side or back. The radiation (which may be coherent or incoherent) is detected by a sensor that displays an image of the target and the beam. The sensor receives the beam directly if the emitter is on the back of the round and by reflection off the target or nearby objects if the emitter faces forward. The round may include a fixed or moveable collimating lens. The emitter may radiate radially from the round to signal troops or devices located along its path. The round may include sensors that gather significant information about chemicals or biological agents, about magnetic or gravitational anomalies or any other remotely detectable property and transmit that information to the sensor by modulating the emitted radiation.

The invention discloses a disturbing gravity-based quasi-geoid land-sea seamless splicing method. In the method, the physical characteristic that the disturbing gravity is not limited by local height datum is fully utilized, a unified earth reference ellipsoid is taken as a coordinate reference frame, the land-sea unified disturbing gravity is calculated by adopting land-sea reference unified global navigation satellite system (GNSS) and gravity data, and the land-sea unified disturbing gravity is introduced to the more strict arithmetic provided by the invention so as to realize quasi-geoid land-sea seamless splicing. Different from the conventional fit algorithm for calculating land-sea height anomaly by utilizing gravity anomaly and a Stokes formula, the method is strict theoretically, and can eliminate result errors caused by the oddness of a kernel function.

The invention discloses a marginalized cubature Kalman filter (CKF)-based gravity aided navigation method which comprises the following steps: acquiring position information output by an inertial navigation system and a gravity anomaly value measured by a gravity meter in real time; establishing an output error model of an inertial device and an error equation of the inertial navigation system, and determining the state quantity and measurement quantity; dividing the iteration process into state update and measurement update; taking the observed quantity at each moment in the filtering process as a gravity anomaly value measured by the gravity meter in real time, and estimating an observation predicted value, an autocorrelation covariance matrix, a mutual correlation covariance matrix and Kalman gain; calculating a state estimation value and a state error covariance estimation value according to the obtained state and observation predicted value; correcting the inertial navigation system through output correction according to the obtained navigation parameter error of the inertial navigation system. According to the method, the state estimation is effectively and rapidly realized, filtering is performed in a sampling point form by virtue of a gravity anomaly reference map, an error brought by model inaccuracy is avoided, and the gravity aided navigation can be accurately and rapidly realized.

The invention provides an inertia gravity combined navigation semi-physical simulator which is a device suitable for the theoretical method and engineering application research of an inertia / gravity combined navigation system. A path generator generates ideal data inputted to an inertia measuring unit, a gravimeter simulator, a Doppler log simulator, a deep sounding apparatus simulator and a combined navigation computer; wherein the gravimeter simulator comprises a gravity sensor, a chart of digital gravity anomaly, and a computer; the Doppler log simulator comprises a Doppler log and a computer; the deep sounding apparatus simulator comprises a deep sounding apparatus and a computer; the combined navigation computer is realized by an industrial computer, the synchronous control of the path generator, the inertia measuring unit, the gravimeter simulator, the Doppler log simulator and the deep sounding simulator is realized by a serial port, the transmission and receiving of information are performed on the inertia measuring unit, the gravimeter simulator, the Doppler log simulator and the deep sounding apparatus simulator, the combined navigation calculation and estimation analysis are performed, and the result is displayed through a terminal.

A method for evaluating confidence of measuring parameters of a strap-down air-borne gravimeter includes: (1) evaluating accuracy and stability of a sensor of the strap-down air-borne gravimeter; (2) evaluating initial alignment accuracy of the strap-down air-borne gravimeter; (3) evaluating integrated navigation accuracy of the strap-down air-borne gravimeter; (4) evaluating carrier acceleration calculating accuracy; and (5) integrating evaluation parameters by reflecting confidence of a measuring data source through the accuracy and the stability of the sensor, reflecting confidence of data acquisition and calculation in measuring process through performance parameters in the measuring process, accordingly calculating final measuring results, namely, calculating confidence indexes of gravity anomalies, respectively calculating confidence of an acceleration meter, a gyroscope, initial alignment, integrated navigation and carrier acceleration calculating accuracy, and finally distributing corresponding weight of the calculated confidence to evaluate the confidence of the sensor of the strap-down air-borne gravimeter. The method has the advantages of simple principle, fine operability, high practicability, easiness in popularization and the like.

The invention discloses a matching method of a gravity-aided inertial navigation system. The manner that search regions can be changed is adopted, the search regions change in real time along with changes of inertial navigation precision, the searching range is effectively reduced, the number of alternative matched track points is reduced, and the searching efficiency is improved; the alternative matched track points are further screened by looking for points approaching a gravity abnormal value measured by a gravity meter in each search region; the number of the alternative matched tracks is effectively reduced under the constraint condition that the distance between each matched tracking point and the corresponding inertial navigation output track point deviates increasingly and changes in a certain range, and the matching efficiency is improved.

The invention discloses a depth-varying-to-density earth crust expansion coefficient thermal calibration gravity anomaly retrieval method. In the calculation process of a gravity retrieval earth crust expansion coefficient, a lithosphere thermal gravity anomaly calibration and depth constraint strategy is introduced, according to an iterative computation method of multiple parameter constraints such as a submarine topography, a sedimentary thickness, magnetic anomaly, an ocean age isochron and earthquake reflection and refraction, a distortion effect, caused by earth crust density changes resulted from lithosphere thermal disturbance, on gravity interpretation is corrected, and a basis is provided for knowing earth crust expansion and cracking processes.

The invention provides a method for matching filter by gravity anomaly based on damping strapdown inertial navigation. The periodic oscillation property of a system can be damped by adding a gravity anomaly measurement module and adding a damping algorithm and a gravity anomaly value Kalman filter matching algorithm into a inertial navigation strapdown algorithm on the premise of not changing the precision of a system accelerometer and a gyroscope and not destroying the concealing property and independence of a strapdown inertial navigation system, the system error can be reduced, and the navigation precision of the system can be improved. According to the method, three periodic oscillation properties (including Schuler cycle oscillation, earth cycle oscillation and Foucault cycle oscillation) in the strapdown inertial navigation system can be eliminated by virtue of the damping property, so that the precision of the strapdown inertial navigation system can be improved to a certain extent. Navigation information acquired by the strapdown inertial navigation system can be corrected by the gravity anomaly value matching filter method.

The invention provides a selection method for a suitable matching area of gravity-aided inertial navigation to overcome the technical problem that a traditional suitable matching area selection method neglects the directivity of a suitable matching area. According to the method, the navigation area of a carrier is divided into a plurality of subareas; classified statistic and analysis are carried out on gravity abnormal data in each subarea; a gravity abnormity three-dimensional curved surface isotropic coefficient, a gravity abnormity variation coefficient, a gravity abnormity skewness coefficient and a gravity abnormity kurtosis coefficient of each subarea are separately obtained; comprehensive characteristic parameter expression is constructed according to the relationship between each parameter and gravity abnormity probability distribution; thus, selection of the suitable matching area is realized.

The invention provides a bayesian estimation-based particle filter gravity-assisted inertial navigation matching method. When solving non-linear problems, particle filter prevents linearization-caused errors and solves the problem that the traditional point matching Sandia algorithm easily produces divergence in a large-gravity anomalous change matching area. Through use of inertial navigation position information as quantity of state, a gravimeter measured value as observed quantity, bayesian estimation-based particle filter, and a random sample average replacing a probability density function conditional mean, inertial navigation system state variable is estimated.

The invention discloses a method for recognizing a small fracture through gravity. The horizontal gradient calculation is carried out on gravity anomaly, horizontal gradient values of mesh points are compared with horizontal gradient values of adjacent points on the two sides in the east-west direction, the north-south direction, the north-west direction and the north-east direction one by one, when the horizontal gradient values of the mesh points are greater than the horizontal gradient values of the adjacent points on the two sides in one or more directions at the same time, the mesh points are determined as points with the maximum horizontal gradient value, the coordinates and gradient values of the mesh points are recorded, the grid points with the maximum horizontal gradient value are drawn to a plane graph, and then the small fracture can be recognized out. Large-scale fracture information can be extracted from gravity data, small-scale fracture information can also be extracted, and particularly when fractures of different sizes exist, fractures of different sizes can be recognized out at the same time.

The invention discloses a method for optimizing an underwater gravity matching navigation adaptation zone. The method comprises the steps that a gravity field characteristic parameter is acquired; anindex evaluation model is constructed based on a principal component analysis criterion and a weighted average principle according to the gravity field characteristic parameter; the value of the gravity field characteristic parameter is taken as input of the index evaluation model, and an evaluation score is output by the index evaluation model; the underwater gravity matching navigation adaptation area is determined and output according to the evaluation score. The method for optimizing the underwater gravity matching navigation adaptation zone has the advantages that gravity anomaly standarddeviation, slope standard deviation, roughness, gravity anomaly difference entropy, fractal dimension and other main gravity field characteristic parameters are comprehensively analyzed, the principal component analysis criterion and the weighted average principle are combined, a principal component weighted average normalization method is proposed, a total characteristic parameter index of eacharea of a gravity anomaly reference map is obtained, then good adaptation areas, general adaptation areas and non-adaptation areas are divided according to the total characteristic parameter index, and the rationality of the division index is verified.

A method for calculating performance of satellite gravity field measurement by low-to-low satellite-to-satellite tracking, includes: acquiring parameters of gravity satellite system; calculating an effect of satellite loads on the power spectrum of nonspherical perturbation potential, so as to obtain an degree error variance; comparing degree error variance with degree variance given by Kaula Rule, and when degree error variance equals degree variance, considering that the highest degree of gravity field measurement is obtained, calculating geoid degree error and its accumulative error, gravity anomaly degree error and its accumulative error, so as to obtain the performance of satellite gravity field measurement by low-to-low satellite-to-satellite tracking. The method is capable of evaluating gravity field measurement performance quickly and effectively, obtaining a rule of effects of the gravity satellite system parameters on the gravity field measurement performance, so as to avoid shortcoming caused by numerical simulation.

The invention discloses a method for positioning and detecting low-density concealed ore bodies in a gallery gravity total spatial domain. The method includes the steps that firstly, field gallery gravity and gravity gradient observation is conducted, various corrections are conducted on observation data and include the earth tide correction, the null shift correction, the terrain correction, Bouguer correction, latitude correction, gallery correction, gob correction, backfilling zone correction and the like; secondly, concealed ore body positioning detection is conducted according to the gravity anomaly and the gravity gradient anomaly in the X direction, the Y direction and the Z direction, wherein the gravity anomaly and the gravity gradient anomaly are obtained after correction is conducted. The method solves the problems that metal ore bodies are difficult to position in the total spatial domain, and according to other object detection methods, the deep ore bodies are difficult to position and detect accurately due to the influences of electromagnetic interference and anomaly multiple solutions.

The invention relates to an inertial navigation system with a gravity disturbance autonomous compensation function and a method thereof. The inertial navigation system is technically characterized bycomprising a gimbaled inertial navigation system, an inertial information measurement module and a gravity gradient measurement module; the gimbaled inertial navigation system comprises a tri-axial platform frame, a platform body and a platform base; the inertial information measurement module comprises an inertial measurement unit and a gravity measurement module; the inertial measurement unit outputs line motion information and angular motion information for navigation solution; the tri-axial platform frame stabilizes the platform body under a geographic coordinate and simultaneously outputscarrier position, speed, heading and attitude navigation information; and the gravity measurement module and the gravity gradient measurement module synchronously measure gravity anomaly informationof a current position of a carrier and full tensor gravity gradient information and calculate gravity vector information of the current position of the carrier, and the gravity vector information is used for the navigation solution of the inertial measurement unit. The precision of the inertial navigation system can be improved.

The invention relates to a strapdown underwater dynamic gravity measurement instrument and belongs to the field of gravity measurement. The system is mainly composed of an inertia measurement unit, adata system, a Doppler velocimeter, a depthometer, an ultrashort baseline hydroacoustic positioning device and an underwater pressure cabin, wherein installing holes are formed in the bottom of the underwater pressure cabin, and the underwater pressure cabin can be fixedly connected with an underwater dynamic carrier through bolts; the Doppler velocimeter measures the velocity to a seabed or a seacurrent, the depthometer measures the depth of a gravity meter, and the ultrashort baseline hydroacoustic positioning device measures the position of the gravity meter; and measurement results of themeters are used as external observation quantities, united filtering is performed on the measurement results and a strapdown inertial navigation solving result of the inertia measurement unit, and gravity anomaly solving is performed after all navigation parameters and specific force measurement values are obtained. The strapdown underwater dynamic gravity measurement instrument meets the demandof underwater dynamic gravity measurement and has the advantages of being low in manufacturing cost, high in measurement efficiency, large in covering area, adaptive to a dynamic measurement environment, close to a seabed gravity signal source and the like.

The invention relates to a dynamic precision assessment method based on a movable base gravity meter, and the method comprises the steps: enabling the movable base gravity meter to be installed on a specially designed test vehicle, and selecting a proper test road segment for reciprocating running measurement; and achieving the precise and effective assessment of inner coincidence precision of the movable base gravity meter through the comparison of multiple gravity abnormal values of the same road segment. Moreover, the method is simple, is easy to implement, is low in cost, and is high in efficiency. In addition, a processing method for gravity abnormality data is strong in anti-interference capability, is higher in data processing precision, and is especially suitable for the gravity abnormality extraction of a high-precision movable base gravity meter. The method can be used for assessing the inner coincidence measurement precision of the movable base gravity meter, and is suitable for the field running test of the movable base gravity meter.

The invention relates to an airborne-gravity least-square downward-continuation analysis algorithm based on upward continuation. The main technical characteristics of the algorithm include: establishing analysis relationships of airborne-gravity upward-continuation and downward-continuation and vertical partial derivatives of each order of gravity anomalies on survey line heights according to a Taylor series expansion model; and upwardly continuing airborne-gravity data through a Poisson integral formula to obtain a gravity anomaly value on each height, calculating the vertical partial derivatives of each order of the gravity anomalies on the survey line heights on the basis of a least-square theory, and substituting the vertical partial derivatives of each order into a Taylor series expansion formula to realize stable calculation of downward continuation. According to the algorithm, an airborne-gravity downward-continuation calculation process is converted into two steps of upward-continuation calculation and vertical-partial-derivative calculation, interference of data observation noises on a calculation result is effectively suppressed through processing of the first step, stable calculation of the inverse problem of downward continuation is successfully realized through processing of the second step, and the inherent ill-posed-nature problem of downward-continuation calculation is better solved.

The invention provides a method for calculating two-dimensional body gravity anomaly. According to the method, complex two-dimensional body model representation and rectangular model gravity anomaly calculation steps are implemented, wherein the rectangular model gravity anomaly calculation comprises the steps of weighting coefficient calculation, one-dimensional discrete convolution calculation and gravity anomaly synthesis. According to the method, unity of gravity anomaly in efficiency and precision is implemented. According to the method, problems that an existing two-dimensional body gravity anomaly calculation method cannot ensure calculation efficiency and calculation precision simultaneously and requirements of large-scale gravity anomaly data density detailed inversion and human-computer interaction modeling and explanation cannot be met are solved.

The present invention relates to a spatial layering disturbance gravitational field grid model rapid construction method which can effectively solve the problem of obtaining the disturbance gravitation of earth's any height level rapidly and at a high precision. The method comprises the following steps of modifying a conventional integration formula into a convolution form to calculate rapidly by utilizing a convolution theorem; calculating the low-order model gravity anomaly and the residual gravity anomaly to obtain the residual gravity anomaly; carrying out the Fourier transform and the inverse transformation thereof to obtain a residual disturbance gravitation value; calculating a low-order model disturbance gravitation and a final disturbance gravitation to obtain the final disturbance gravitation; comparing a disturbance gravitation precision with a calculation efficiency, at the same time, comparing the efficiency difference with a conventional method. The method of the present invention is easy to operate and apply, can effectively solve the problem of obtaining the disturbance gravitation of earth's any height level rapidly and at the high precision, facilitates the rapid and real-time positioning and control of various spacecrafts when the spacecrafts move, guarantees the safety of the spacecrafts, and possesses a very strong use value.

The present invention discloses a method of positioning and detecting a high density concealed ore body in a full spatial domain by the tunnel gravity. The method is characterized in that firstly, the field tunnel gravity and the gravity gradient are observed, and various correction operations containing the earth tide correction, the null shift correction, the topographic correction, the Bouguer correction, the latitude correction, the tunnel correction, the mined-out area correction, the back filled region correction and the like are carried out on the observation data, and then the concealed ore body is positioned and detected by the corrected gravity abnormity and the gravity gradient abnormity in the X, Y and Z directions. The method solves the problems that a metal ore body is difficult to position in the full spatial domain, and the other geophysical exploration methods are influenced by the electromagnetic interference and the abnormity multiplicity, so that the deep ore body is difficult to position and detect accurately.

A covert tracer round has an infrared emitter of radiation mounted to its front, side or back. The radiation (which may be coherent or incoherent) is detected by a sensor that displays an image of the target and the beam. The sensor receives the beam directly if the emitter is on the back of the round and by reflection off the target or nearby objects if the emitter faces forward. The round may include a fixed or moveable collimating lens. The emitter may radiate radially from the round to signal troops or devices located along its path. The round may include sensors that gather significant information about chemicals or biological agents, about magnetic or gravitational anomalies or any other remotely detectable property and transmit that information to the sensor by modulating the emitted radiation.

The invention discloses a gravity matching method based on robust self-adaptive untracked Kalman filtering. The method comprises the following process of building a system state equation and observation equation of a gravity assistance inertial navigation system filter on the basis of a single-point matching algorithm of the recurrence filtering; performing subtraction on the gravity abnormal reference value extracted from the current moment gravity abnormal pattern and the gravity abnormal practical measuring value to obtain the gravity abnormal difference value; on the basis of the improvedARUKF algorithm, performing filtering on the gravity abnormal difference by using the system state equation and the observation equation of the gravity assistance inertial navigation system filter soas to obtain the position and the variance of a submersible vehicle at the next moment; calculating the submersible vehicle position at each filtering sampling moment in the mode by using the positionand the variance of the submersible vehicle at the next moment; finally obtaining a complete matching track. The matching error can be effectively reduced; the navigation positioning precision of thegravity assistance inertial navigation system is improved.

The invention discloses an optimization method for sea island reef height transmission and belongs to the technical field of geodesy and measuring engineering. Leveling is a conventional method with the advantages of most directness and effectiveness, highest precision and widest application during height transmission, and the using range thereof is influenced in some special areas, for example, during sea island reef height transmission, because leveling equipment cannot be stably used on sea surface, a method for directly measuring the height by using a leveling instrument cannot be used. Therefore, the invention provides an optimization method for sea island reef height transmission, which comprises the following steps of: highly integrating land, coastal zone and sea island gravity data; calculating a land and transmitted sea island reef consistent high-precision whole gravity quasigeoid numerical model through space gravitational abnormal data corrected by height reference system difference; and finally measuring the GPS geodetic height of the known height and the GPS geodetic height of a sea island reef point to be measured by using the known height point in a calculation region so as to finish the height transmission of the sea island reef.

The invention discloses a method for picking up a boundary with abnormal gravity by using a normalized derivative model method which utilizes gravimetric and magnetic data to interpret breakage and other geotectonic boundaries in petroleum and solid mineral exploration. The method comprises steps of: eliminating weak information generated by shallow and near-surface heterogeneous bodies in bouguer gravity anomaly of gravity data by using a low-pass filter; respectively getting a derivative in X axis direction and a derivative in Y axis direction to obtain a horizontal gradient model; determining a coherent signal to obtain curvature properties, the normalized derivative model and a contour map; and determining the boundary with abnormal gravity to be picked up according to a ligature of maximum values of the anomaly. According to the anomaly information obtained by the invention, not only the width of large-scale anomaly is narrowed and thinned, but also the weak anomaly in small scale can be effectively highlighted.