Terrain-Referenced Navigation Fusion for Inertial Drift Correction
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Solution Overview
Problem
Inertial navigation systems suffer from increasing errors over time due to integration issues, while GPS and GNSS systems are susceptible to interference, making terrain referenced navigation systems a more reliable alternative.
Innovation Solution
A terrain referenced navigation system that combines inertial measurement data with terrain-dependent data from generic sensors like strap-down slant range sensors, using a Kalman filter to correct inertial navigation solutions by determining navigation and sensor corrections.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If inertial measurement units are used to determine navigation solution, then navigation assistance is provided, but errors increase over time due to integration issues
Solution Approach 1:
The patent implements a feedback mechanism by continuously comparing inertial navigation solutions with terrain database references and using the discrepancies to correct the inertial measurement unit's accumulated errors. The system processes terrain data from sensors (radar altimeters, cameras) and feeds correction information back to update the navigation solution, thereby maintaining accuracy over time without requiring perfect inertial measurements.
2Adaptability or versatility
If GPS and GNSS systems are used for navigation, then widely used navigation solution is provided, but signals are susceptible to external interference and jamming
Solution Approach 1:
The patent introduces terrain referenced navigation as an intermediary system between the vehicle and satellite-based navigation. Instead of directly relying on GPS/GNSS signals that can be jammed, the system uses terrain features and local sensors as intermediaries to determine position and navigate, providing a backup navigation capability that is resistant to electromagnetic interference and jamming.
3Reliability
If terrain referenced navigation systems are used as alternative to GPS, then resistance to jamming is achieved, but system complexity increases due to multiple sensors and processing algorithms
Solution Approach 1:
The patent applies universality by designing a unified terrain referenced navigation system that can accommodate multiple types of sensors (radar altimeters, cameras, LiDAR) and process various terrain data formats through a common processing framework. The system uses a standardized algorithm architecture that can handle different sensor inputs and terrain database formats, reducing the complexity that would otherwise arise from managing multiple specialized systems.
Data Source
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AI summary
A terrain referenced navigation system for a vehicle is disclosed and includes an inertial measurement unit and one or more generic terrain sensors configured to collect terrain-dependent data. The terrain referenced navigation system includes one or more processors in electronic communication with the generic terrain sensors and the inertial measurement unit, and a memory coupled to the processors. The memory stores data into one or more databases and program code that, when executed by the processors, causes the terrain referenced navigation system to determine a predicted terrain value based on a terrain value, where the terrain value is retrieved from one or more sensor specific terrain databases. The pre-Kalman filter processing values are sent to a Kalman filter. The Kalman filter determines navigation corrections and sensor corrections based on the pre-Kalman filter processing values.