Terrain Aided Navigation Map Quality Weighting
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Terrain aided navigation systems face accuracy issues over featureless terrain due to difficulty in correlating radar data with digital elevation maps, resulting in low position updates, while mountainous and urban areas provide high accuracy due to easily correlatable terrain features.
Innovation Solution
A navigation system comprising a navigation processor, inertial navigation unit, digital elevation map, radar altimeter, and map quality processor, where the radar altimeter's position solution is weighted based on a map quality factor calculated from digital elevation map data, combining it with inertial navigation data to enhance position accuracy.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If terrain aided navigation uses radar data correlation with digital elevation maps, then navigation accuracy is improved over mountainous and urban terrain, but accuracy deteriorates over featureless terrain such as water or flat desert
Solution Approach 1:
The system applies different weighting factors to terrain correlation data based on the local terrain characteristics. A map quality factor is calculated that varies spatially across different terrain types, allowing high weighting over mountainous/urban terrain where correlation is accurate, and low weighting over featureless terrain where correlation fails, thus adapting the navigation solution quality to local conditions
Solution Approach 2:
The weighting factor applied to terrain correlation position solutions is made dynamic rather than static. The map quality factor changes continuously based on the current terrain environment, enabling the system to adapt in real-time to varying terrain conditions along the flight path, transitioning between relying on terrain correlation and inertial navigation as conditions dictate
2Measurement precision
If the system relies on terrain correlation for position updates, then position accuracy is enhanced in areas with terrain features, but the system becomes unreliable over featureless terrain
Solution Approach 1:
The system implements feedback through the map quality factor calculation that continuously monitors terrain correlation effectiveness. When terrain features are detected that enable good correlation, the system increases confidence in terrain-based position updates. When featureless terrain is detected, the system reduces reliance on terrain correlation, automatically adjusting the navigation solution based on feedback from the terrain correlation process itself
Solution Approach 2:
The map quality factor acts as an intermediary that mediates between terrain correlation data and the final navigation solution. Rather than directly using terrain correlation results or rejecting them outright, the intermediary weighting factor smoothly transitions the contribution of terrain data to the navigation solution based on terrain suitability, ensuring reliable operation across all terrain types
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 improves navigation accuracy by weighting terrain correlated position solutions based on map quality factors, effectively addressing the low accuracy over featureless terrain and maintaining high accuracy in mountainous and urban areas, thereby enhancing overall navigation precision.
Implementation Method 1
a radar altimeter comprises a terrain correlation processor configured to receive map data from the digital elevation map and provide a position solution based on radar data
Data Source
AI summary
A navigation system is described which includes a navigation processor, an inertial navigation unit configured to provide a position solution to the navigation processor, and a digital elevation map. The described navigation system also includes a radar altimeter having a terrain correlation processor configured to receive map data from the digital elevation map and provide a position solution based on radar return data to the navigation processor. A map quality processor within the navigation system is configured to receive map data from the digital elevation map and provide a map quality factor to the navigation processor which weights the position solution from the terrain correlation processor according to the map quality factor and determines a position solution from the weighted terrain correlation processor position solution and the position solution from the inertial navigation unit.