Terrain-Gradient Navigation for INS Drift Correction
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Solution Overview
Problem
Inertial Navigation Systems (INS) in ground vehicles suffer from positional drift due to sensor errors, and satellite-based navigation solutions are unreliable, especially in environments where signals are jammed or spoofed, necessitating a more reliable and self-contained navigation method.
Innovation Solution
A ground vehicle navigation system that integrates an inertial navigation system with a terrain gradient-based navigation unit, using terrain gradient data from a stored map to correct INS errors through an iterative algorithm, which updates the system error state with position estimates from both systems.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If satellite-based navigation solutions are used to correct INS errors, then navigation accuracy is improved, but reliability deteriorates in environments where signals are jammed or spoofed
Solution Approach 1:
The patent introduces terrain gradient data as an intermediary reference system that does not depend on satellite signals. The terrain map provides a static, reliable reference framework that can be used to correct INS drift without requiring external electromagnetic signals, thus resolving the contradiction between accuracy and reliability in signal-denied environments
Solution Approach 2:
The system uses the vehicle's own orientation measurements from the IMU combined with stored terrain gradient data to self-correct navigation errors. This self-service approach eliminates dependence on external satellite signals while maintaining navigation accuracy through iterative correction algorithms that process onboard sensor data
2Measurement precision
If conventional TRN systems use Barometric-Inertial mixed altitude and radar altimeters, then altitude estimation is provided, but the system complexity increases and signal emissions are required
Solution Approach 1:
The patent extracts and eliminates the barometric and radar altimeter components from the TRN system, retaining only the essential inertial navigation elements. By removing these complex signal-emitting components while preserving the core navigation function through terrain gradient correlation, the system reduces complexity and eliminates unnecessary signal emissions
Solution Approach 2:
The system replaces expensive, complex altimeter hardware with a computational approach that uses existing IMU orientation data and pre-stored terrain gradient information. This substitution eliminates the need for costly hardware components while achieving equivalent or superior altitude estimation through algorithmic processing
Data Source
AI summary
A ground vehicle navigation system includes an inertial navigation system arranged to output an orientation estimate of the ground vehicle and a first position estimate of the ground vehicle, a terrain map comprising terrain data, a terrain gradient based navigation unit arranged to output a second position estimate of the ground vehicle based on a comparison between the orientation estimate and terrain gradient data extracted from the terrain map and an iterative algorithm unit arranged to determine a system error state in each iteration. In each iteration the iterative algorithm unit is arranged to receive the first position estimate and the second position estimate; and update the system error state for the next iteration based on the system error state, the first position estimate and the second position estimate. The iterative algorithm unit may then apply the updated system error state to the INS measurements.