GNSS Autonomous Navigation via DRO Inter-Satellite Links
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Solution Overview
Problem
Current satellite navigation systems, such as GNSS, face challenges in achieving accurate autonomous navigation due to signal delays in the troposphere and ionosphere, and slow changes in satellite-ground measurement geometry, which affect positioning and timing accuracy.
Innovation Solution
The method involves optimizing a cislunar Distant Retrograde Orbit (DRO) and establishing inter-satellite measurement links using a Low Earth Orbit (LEO) data relay satellite to autonomously determine the position and velocity of GNSS satellites without ground-based measurement, leveraging the asymmetry of the earth-moon three-body gravity field for absolute orbit determination.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If ground-based measurement and control is used for satellite navigation, then positioning and timing services can be provided, but signal delays in the troposphere and ionosphere affect measurement accuracy
Solution Approach 1:
The patent extracts the measurement function from ground-based stations and relocates it to space-based satellites. By using inter-satellite links where satellites measure each other's positions in space, the system eliminates the need for signals to propagate through the atmosphere, thereby removing the harmful atmospheric delay effects while maintaining positioning accuracy
Solution Approach 2:
The patent introduces an intermediary reference satellite in a DRO orbit as a mediator for autonomous navigation measurements. This reference satellite serves as a stable spatial benchmark that enables other satellites to determine their positions relative to it through inter-satellite links, providing an alternative to ground-based measurement without atmospheric interference
2Measurement precision
If conventional satellite-ground measurement geometry is used, then navigation services can be provided, but the slow change in measurement geometry is not conducive to accurate position and clock difference calculation
Solution Approach 1:
The patent transitions from static ground-based measurement geometry to dynamic inter-satellite measurement geometry. Satellites in different orbits (MEO, GEO, IGSO) continuously change their relative positions, creating dynamically evolving measurement geometries that rapidly update spatial relationships and improve position calculation accuracy
Solution Approach 2:
The patent adds a new dimension to measurement geometry by utilizing the vertical dimension of space with satellites at different orbital altitudes and inclinations. The DRO reference satellite provides a unique spatial perspective from a different orbital plane, creating three-dimensional measurement geometry that enhances position determination capability
3Extent of automation
If autonomous navigation is implemented using inter-satellite links, then independence from ground control is achieved, but the absolute orientation of orbit planes cannot be determined in a symmetric gravitational field
Solution Approach 1:
The patent exploits the asymmetry of the earth-moon three-body gravitational field to break the symmetry problem. By positioning a reference satellite in a DRO orbit that experiences varying gravitational forces from both Earth and Moon, the system creates an asymmetric reference frame that enables determination of absolute orbit orientation without ground-based references
4Duration of action of stationary object
If stable long-term navigation is required, then halo orbits can be used but they require frequent orbit maneuvers to maintain stability
Solution Approach 1:
The patent selects a DRO orbit that is inherently stable and requires minimal maintenance. The DRO's natural orbital characteristics allow it to maintain its position and provide stable autonomous navigation references without requiring active orbital correction maneuvers, thereby eliminating energy loss and reducing operational complexity
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
This approach enables high-accuracy, long-term autonomous navigation of GNSS satellites with reduced orbital maintenance costs and independence from ground control, as the DRO provides a stable and accurate measurement link through LEO data relay satellites, unaffected by atmospheric delays.
Implementation Method 1
establishing measurement links, by a low earth orbit (LEO) data relay satellite, with a DRO satellite and the GNSS satellites respectively, and measuring an inter-satellite distance
Implementation Method 2
there is a region in an earth-moon three-body orbital space, whose magnitudes influenced by the gravitational effect of the earth and the moon can be comparable, and the two are no longer different in order of magnitude. The distribution of the gravity field in this region is asymmetric
Data Source
AI summary
Disclosed is a method for achieving space-based autonomous navigation of global navigation satellite system (GNSS) satellites, and relates to the field of satellite navigation technologies. The method includes the following steps: optimizing a DRO, and establishing a dynamic model of an earth-moon space satellite orbit; establishing measurement links, by a low earth orbit (LEO) data relay satellite, with an earth-moon space DRO satellite and a GNSS respectively, and measuring an inter-satellite distance for modeling and linearization; adopting an extended Kalman filter (EKF) method to process inter-satellite measurement data, and autonomously determining a position and velocity of the global navigation satellite system without depending on the ground measurement and control support.