5 results about "Earth's rotation" patented technology

This invention provides a satellite onboard orbit conversion method and system. The method includes: calculating the corrected Julian day at the current time and calculating the Greenwich Mean Sidereal Time Angle based on the corrected Julian day; converting the Greenwich Mean Sidereal Time Angle into radians; calculating the Earth rotation matrix from the J2000 system to the WGS84 system based on the converted radians; pre-calculating the Earth nutation and precession correction matrices as modifiable parameters for satellite commands and updating them periodically; calculating the conversion matrix from the J2000 system to the WGS84 system based on the Earth nutation and precession correction matrices and the Earth rotation matrix; and calculating the satellite position and velocity in the WGS84 system based on the conversion matrix, thereby realizing the satellite onboard orbit conversion. This invention addresses the need for converting EP satellite onboard orbit information from an inertial frame to the WGS84 coordinate system, meets the requirements for short message stand-alone operation, and can provide a reference for on-orbit conversion of other satellites.

To provide a compact and easy-to-use azimuth detection method, azimuth detection device, and surveying device. [Solution] The system includes a sensor unit 7 that detects tilt and rotation relative to the horizontal, and a flywheel 18 provided on the sensor unit that has a rotation axis extending in the vertical direction. The flywheel is rotated at a constant speed, and the flywheel is tilted to generate a gyroscopic moment in order to counteract the change in tilt that occurs in accordance with the rotation of the Earth, and the direction of the Earth's axis (north or south) can be determined from the direction of the gyroscopic moment.

This invention discloses a method for calculating the sub-satellite point based on the SGP4 orbital model, relating to the field of satellite navigation and orbit prediction technology. The polar spherical projector of this invention eliminates longitude jumps in latitude >75°, ensuring continuous trajectory output for scenarios such as polar scientific expeditions and glacier monitoring. By directly mapping three-dimensional radial information to generate latitude, it avoids the iterative convergence problem of the ellipsoidal model, ensuring natural symmetry of the North and South Poles coordinates and continuous longitude domain. Second-order differential compensation of the mean anomaly angle, combined with dynamic correction of the Earth's rotational angular velocity, strictly aligns the UTC timestamp with the orbital position. It suppresses the cumulative error generated by traditional linear interpolation at perigee. It enhances adaptability to complex perturbation environments; atmospheric drag vectorization compensation captures real-time aerodynamic direction through relative velocity cross terms, combined with continuous processing of the density index model, significantly improving the orbital attenuation prediction accuracy of low-Earth orbit satellites during geomagnetic storms.

This invention discloses a closed-loop celestial object tracking and imaging method and system based on real-time analysis of starry sky images. The invention identifies celestial objects from starry sky images and calculates imaging parameters; based on Earth rotation data and current field-of-view parameters, it calculates the instantaneous linear drift velocity and field rotation angular velocity of the celestial object to be tracked on the image sensor plane. The long-exposure drive signal is compensated based on the calculated instantaneous linear drift velocity and field rotation angular velocity of the current frame and adjacent frames to counteract star point drift during the long exposure process. Alternatively, by calculating the relative displacement and rotation angle between adjacent frames and the current frame in consecutive short-exposure images, each subsequent frame is aligned, and all frames are pixel-level superimposed to synthesize the final long-exposure image. This invention achieves significant simplification in hardware cost and structure, requiring only one imaging unit to complete high-precision pointing calculation and drift compensation.

This invention proposes a method for joint calculation of Earth rotation parameters and short-term forecasting using regional network satellite-ground-satellite joint methods, belonging to the field of satellite navigation technology. This invention utilizes satellite-ground observation data from a limited number of regional stations, along with inter-satellite link measurement data, to perform joint orbit determination and ERP parameter calculation. Considering the limited amount of accumulated ERP data, a real-time short-term ERP forecasting method based on historical calculations is employed, and the method is compared with IERS CO4 for accuracy evaluation.