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3308results about How to "Reduce precision" patented technology

Visual navigation/inertial navigation full combination method

The invention relates to a visual navigation / inertial navigation full combination method. The method comprises the following steps: first, calculation of visual navigation: observation equations are listed based on collinearity equations, carrier positions and attitude parameters are obtained through the least square principle and adjustment,, and variance-covariance arrays among the parameters are calculated; second, calculation of inertial navigation: navigation calculation is carried out in the local horizontal coordinates, carrier positions, speeds and attitude parameters of each moment are obtained, variance-covariance arrays among the parameters are calculated; third, correction of the inertial navigation system through the visual system: by means of the Kalman filtering, navigation parameter errors and device errors of the inertial navigation system are estimated, and subjected to compensation and feedback correction, and therefore the optimal estimated values of all the parameters of the inertial navigation system are obtained; fourth, correction of the visual system through the inertial navigation system: all the parameters of the visual system are corrected through the sequential adjustment treatment. Compared to the prior art, the method has advantages of rigorous theories, stable performances, high efficiency and the like.
Owner:TONGJI UNIV

Wax injection mold for investment casting of hollow turbine blades and method for rapidly manufacturing wax injection mold

The invention discloses a wax injection mold for investment casting of hollow turbine blades and a method for rapidly and accurately manufacturing the wax injection mold. The mold consists of a cavity mold, a mold core and an accessory structure, wherein the cavity mold comprises an upper mold and a lower mold of a combined structure; each mold block forming the cavity mold consists of an external aluminum mold frame, an internal cast zinc alloy inlay and a conformal cooling copper pipe embedded into the inlay; a mold core positioning piece which can be decomposed at a high temperature is arranged on a longitudinal rib of the mold core; and water-soluble core blocks used for forming exhaust openings in the rear edges of the turbine blades are arranged on rear edge ribs of the mold core. The matching precision of the mold core positioning piece and the cavity mold is guaranteed by adopting a cavity mold interior running-in method, and the matching precision of the water-soluble core blocks and the cavity mold is guaranteed by adopting a cavity mold interior adhesion method. The wax injection mold disclosed by the invention is low in manufacturing cost and short in period, and the high wax pattern precision and core positioning precision can be obtained.
Owner:NANJING UNIV OF AERONAUTICS & ASTRONAUTICS

3D (three-dimensional) printing system structure

InactiveCN103831975AGuaranteed uptimeReduced motor modulationOptical axisDrive shaft
The invention relates to a 3D (three-dimensional) printing system structure. The 3D (three-dimensional) printing system structure comprises a lifting printing platform, a dual-screw dual-optical-axis Z-shaft driving mechanism, an X-shaft drive mechanism, a Y-shaft drive mechanism as well as a stationary object carrying platform, wherein the printing platform is provided with an X-shaft drive motor and a Y-shaft drive motor; the two motors are respectively connected to a pair of driven bearings by synchronous belts at two ends of the driving shaft; double slide shafts in the X direction and the Y direction are both provided with slide seats; two pairs of slide seats are respectively connected by an X cross beam and a Y cross beam, and the two cross beams respectively penetrate through a 3D printer head; a driving motor of the dual-screw dual-optical-axis driving mechanism and the driving shaft are connected by the synchronous belt; the position of the driving motor can be adjusted randomly. The X-shaft drive mechanism, the Y-shaft drive mechanism and the driving shaft operate individually, so that the motion modulation is reduced; the dual-screw dual-optical-axis driving mechanism has favorable stability, so that the printing platform is stressed in a balance manner; the driving in each direction is stable; the 3D printing precision is improved.
Owner:UNIV OF SCI & TECH OF CHINA

Machine-vision based liquid level detection device and method

The invention discloses a machine-vision based liquid level detection device and method. In the method, algorithm processing is carried out on a field liquid level image acquired by using an infrared camera to obtain real-time liquid level height information so as to obtain the instant height of the liquid level. In order to obtain the height information of the liquid level accurately and efficiently, five self-designed algorithms including a cameral distortion correction algorithm, a self-adaptation detection coordinate setting algorithm, a liquid level line segmentation algorithm, a data filter algorithm and a data setting algorithm are used in the machine-vision based liquid level detection device; and meanwhile, in order to implement the algorithms effectively, a calibration manner is introduced in the invention and is applied to a target tracking process of a camera. In the invention, a single-chip microcomputer of an ARM (Advanced RISC (Reduced Instruction Set Computer) Machine) series is used as a main processor. By adoption of self-adaptation coordination setting, the device is not only suitable for open type and / or closed type liquid level detection environments but also suitable for mechanical equipment positioning and product counting, and has a very broad application prospect.
Owner:HUNAN UNIV

Whole attitude angle updating method applied to agricultural machinery and based on nine-axis MEMS (micro-electromechanical system) sensor

The invention discloses a whole attitude angle updating method applied to agricultural machinery and based on a nine-axis MEMS (micro-electromechanical system) sensor. The whole attitude angle updating method applied to agricultural machinery and based on the nine-axis MEMS sensor comprises the following steps: a gyroscope error model, an electronic compass calibration ellipse model and a seven-dimensional EKF (extended Kalman filter) model are established, and parameter vectors of corresponding motion attitudes of a vehicle body are set; data including the acceleration, the angular velocity and the geomagnetic field intensity of vehicle body motion are acquired in real time; the angle, the speed, the location information and the heading angle of the vehicle body are calculated through the established gyroscope error model and electronic compass calibration ellipse model; data fusion processing is performed on the angle, the speed, the location information and the heading angle of the vehicle body through the seven-dimensional EKF model, and the motion attitude angle of the vehicle body is updated in real time. The method comprising the steps has small errors and high precision and is stable and reliable.
Owner:SHANGHAI HUACE NAVIGATION TECH

Method for calibrating star sensor

The invention relates to a method for calibrating a star sensor, which can effectively solve the problems of low calibrating speed, low efficiency and high hardware requirements of the star sensor. The method comprises the following steps of: calibrating internal parameters of the star sensor to obtain a coordinate of a mark point in a coordinate system of a photogrammetric system; carrying out image processing on a picture and calculating internal parameters of cameras; establishing a transit surveying coordinate system; carrying out measurement on a manual surveying mark of a calibrating field by using a transit surveying system to obtain a three-dimensional coordinate of the manual surveying mark in the coordinate system of the transit surveying system; carrying out common point conversion by utilizing a three-dimensional coordinate value to obtain a conversion relation of the coordinate system of the calibrating field and the coordinate system of the transit surveying system and converting the coordinate system of the transit surveying system and a cubic prism coordinate system into the coordinate system of the calibrating field; and taking a picture of the calibrating field again to obtain a relation of the two cameras and the cubic prism coordinate system. The method for calibrating the star sensor of the invention has the advantages of simple calibrating process, low required precision for the hardware, high calibrating precision and high speed, greatly improves the working efficiency and is an innovation on the calibration of the star sensor.
Owner:BEIJING INST OF CONTROL ENG +1

Precise point positioning and inertia measurement tightly-coupled navigation system and data processing method thereof

InactiveCN102508277AImprove initial convergence speedSolve the continuous dynamic positioning problemSatellite radio beaconingCarrier signalNavigation system
The invention discloses a precise point positioning and inertia measurement tightly-coupled navigation system and a data processing method thereof. The navigation system comprises an inertia measurement unit, an inertia measurement processing module, a global positioning system (GPS) receiver and a Kalman filtering calculation module. The inertia measurement unit outputs inertia measurement data of a carrier; the inertia measurement processing module receives a digital signal output by the inertia measurement unit, calculates the data of the position, the speed, the gesture and the heading of the carrier through navigation integration, and calculates a pseudo-range, a carrier wave and a carrier wave change rate relative to the inertia measurement unit; the GPS receiver is used for outputting precise point positioning information; the Kalman filtering calculation module receives the output signals of the inertia measurement processing module and the GPS receiver, calculates correction parameters through multi-state Kalman filtering and feeds the correction parameters back to the inertia measurement processing module; and the inertia measurement processing module receives the correction parameters and calculates navigation data. By the system and the method, the defect that GPS signals are weak under the condition that a satellite has a poor geometric structure or in shielded or half-shielded areas is effectively overcome.
Owner:CHINA UNIV OF MINING & TECH

Radar target attribute scattering center feature extraction method based on sparse decomposition

The invention discloses a radar target attribute scattering center feature extraction method based on sparse decomposition. The radar target attribute scattering center feature extraction method based on the sparse decomposition mainly solves the problems in an existing method capable of segmenting an image to extract attribute scattering center based on the radar image that models are unmatched, features are easy to lose, and parameter estimation accuracy is low. The implementation process includes the following steps: building a scattering center intensity threshold by using noise samples, conducting an intensive scattering center test in the radar image and confirming a values set of a scattering center parameter, obtaining a target attribute scattering center parameter super-resolution estimation set according to attribute scattering center models by using coordinate repeated decline technology to build a super-resolution dictionary through solving the problem of 0 norm optimization, and extracting geometric dimensioning features of the target and important components of the target according to the scattering center parameter set. The radar target attribute scattering center feature extraction method based on the sparse decomposition is capable of effectively extracting the target attribute scattering center and the super-resolution scattering center parameter, accurately estimating the geometric dimensioning features of the target and the important components of the target, and can be used for radar target classification and identification.
Owner:XIDIAN UNIV
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