Digital Terrain Map Ranging for Stable Projectile Impact Prediction
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Solution Overview
Problem
Existing terrain-referenced navigation systems for aircraft face instability in projectile impact point calculations due to iterative loops that are sensitive to terrain geometry and gradients, leading to unpredictable outcomes.
Innovation Solution
A direct comparison of the projectile's fall line with terrain data is performed using a digital terrain map, eliminating the need for iterative loops by integrating fall line calculations within the TRN system, and utilizing a single processor for position, fall line, and impact point calculations.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If an iterative loop between TRN system and independent ranging system is used to calculate projectile impact point, then the system can provide real time visibility of impact point, but the stability becomes dependent on terrain geometry and intercept angle, leading to potential instability
Solution Approach 1:
The patent merges the independent ranging system functions into the TRN system by implementing a fall line calculation unit within the TRN system. This integration eliminates the iterative loop between separate systems, removing the stability issues associated with terrain geometry and intercept angles while maintaining real-time impact point calculation capability.
Solution Approach 2:
The patent extracts the fall line calculation functionality from the independent ranging system and incorporates it directly into the TRN system. This extraction eliminates the need for the iterative feedback loop between separate systems, thereby resolving the stability problems caused by unfavorable terrain geometry and intercept angles.
2Adaptability or versatility
If separate avionics systems are used for TRN and ranging functions, then each system can be independently optimized, but the overall system complexity increases and iterative loops introduce stability risks
Solution Approach 1:
The patent combines the TRN system and ranging system into a single integrated system. The fall line calculation unit is implemented within the TRN system, allowing both navigation and projectile impact point calculation functions to operate within one avionics system, thereby reducing overall system complexity while maintaining full functional capability.
Solution Approach 2:
The integrated TRN system performs multiple functions: it provides terrain-referenced navigation capabilities while simultaneously calculating projectile fall lines and impact points. This multi-functionality eliminates the need for separate dedicated ranging systems while maintaining all required capabilities.
Data Source
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AI summary
A terrain-referenced navigation system (600) for an aircraft comprises: a stored digital terrain map (606); a position calculation unit (608) arranged to calculate aircraft position relative to the stored digital terrain map (606) to determine a terrain-referenced aircraft position; a fall line calculation unit (612) arranged to calculate a fall line for a projectile starting from the terrain-referenced aircraft position as a launch point; and an impact point calculation unit (614) arranged to directly compare the fall line with the digital terrain map, by incrementally comparing a height of the projectile along the fall line with a height of the terrain according to the stored digital terrain map (606) in order to find an expected impact point on the terrain.