Orbital Dynamics Model Replaces IMU Accelerometers in Space GNSS Receiver
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Solution Overview
Problem
Conventional GPS/INS ultra-tight coupling (UTC) systems for space-borne applications face challenges in accurately determining the position, velocity, and time (PVT) of satellites due to high rotational motions, intermittent antenna visibility, weak signal reception, and increased sensitivity to timing errors, while also being costly and prone to jamming.
Innovation Solution
The implementation of precise orbital dynamics models and modified INS processing replaces traditional translational motion sensors, allowing for robust PVT determination and long-duration orbit propagation, even with sparse GNSS measurements, and enhancing anti-jam performance and accuracy.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If conventional GPS/INS ultra-tight coupling systems are used for space-borne applications, then PVT determination can be achieved, but the system suffers from high costs, reduced anti-jam performance, and decreased accuracy due to high rotational motions and weak signal reception
Solution Approach 1:
The patent replaces the mechanical inertial measurement unit (IMU) with a software-based orbital dynamics model that uses mathematical equations to predict satellite motion. This substitution eliminates the need for physical sensors while achieving superior accuracy (one meter per hour) compared to conventional IMU systems, and reduces vulnerability to jamming since the system can operate independently of external GPS signals during orbit propagation.
Solution Approach 2:
The patent creates a virtual copy of the satellite's orbital motion through mathematical modeling and simulation. By using orbital dynamics equations to replicate and predict the satellite's trajectory, the system can determine PVT without relying on external GPS measurements, thereby achieving anti-jam performance while maintaining high measurement precision.
2Measurement precision
If traditional translational motion sensors and INS processing are used, then motion sensing is achieved, but the system incurs substantial costs and increased device complexity
Solution Approach 1:
The patent replaces physical translational motion sensors (accelerometers) and complex INS processing hardware with a software-based orbital dynamics model. This model uses mathematical equations to directly compute satellite position and velocity, eliminating the need for expensive space-qualified inertial sensors and reducing overall system complexity while maintaining high measurement precision.
Solution Approach 2:
The patent extracts and removes the translational motion sensing function from the system by replacing it with orbital mechanics calculations. By taking out the need for physical accelerometers and complex INS processing, the system achieves motion prediction accuracy without the associated hardware complexity and costs.
3Duration of action of moving object
If conventional UTC systems operate in space environment, then PVT solution is provided, but accuracy deteriorates due to intermittent antenna visibility and high relative velocities
Solution Approach 1:
The patent uses orbital dynamics models to pre-calculate and predict satellite trajectory in advance, allowing the system to maintain accurate PVT determination during periods when GPS signals are unavailable. This preliminary action enables the system to bridge signal outages and maintain continuous accurate navigation throughout the entire orbit duration.
Solution Approach 2:
The patent replaces signal-dependent conventional UTC systems with a physics-based orbital mechanics model that naturally handles the space environment. The mathematical model inherently accounts for orbital motion, Earth rotation, and signal propagation effects, maintaining one meter per hour accuracy regardless of intermittent antenna visibility or high relative velocities.
Data Source
AI summary
A GNSS ultra-tight coupling (UTC) receiver architecture applicable to space borne orbit platforms is described. A receiver in accordance with this architecture retains the rotational motion sensors typically found in an inertial measurement unit (IMU) of a conventional UTC receiver, but replaces the IMU accelerometer sensors with precise orbital dynamics models to predict the translational motion of the platform center of gravity (CG). Drag and radiation pressure may be modeled as well. The various models can be implemented in software. The IMU rotational sensors are retained for compensation of the GNSS antenna lever arm effect due to platform rotation.