Aircraft Vertical Profile Adaptation for GNSS Degraded Navigation
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Solution Overview
Problem
Current navigation systems, particularly RNP navigation, face challenges in maintaining accurate aircraft positioning and safety when the GNSS signal is degraded or lost, especially in urban environments where drones operate, as existing solutions cannot guarantee safety with respect to obstacles without manual intervention.
Innovation Solution
A method implemented on board an aircraft using multi-sensor data fusion, such as a Kalman filter, to estimate a 3D position and determine safety distances, creating a 3D flight corridor that adjusts the vertical profile to avoid obstacles by increasing altitude when conflicts are detected, allowing automatic navigation along a lateral path.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If RNP navigation is used with GNSS signals, then navigation accuracy is improved, but reliability deteriorates when GNSS signals are degraded or lost
Solution Approach 1:
The system pre-computes alternative vertical profiles and safety corridors before GNSS signal loss occurs. When signal degradation is detected, the already-prepared alternative profiles are immediately activated, avoiding the need for real-time computation during critical moments.
Solution Approach 2:
The invention introduces an intermediary system that computes alternative vertical profiles and safety corridors based on uncertain position information. This intermediary computation layer acts as a bridge between the degraded GNSS signals and the navigation system, providing reliable alternative paths when primary navigation becomes unreliable.
2Reliability
If safety distance is increased around estimated position, then safety is improved, but navigation precision deteriorates
Solution Approach 1:
The system applies different safety distance criteria to different spatial locations and flight phases. Safety corridors are computed with varying buffer zones based on local terrain characteristics, obstacle density, and flight phase, rather than applying a uniform safety margin throughout the entire flight path.
Solution Approach 2:
The invention transitions from 2D horizontal safety zones to 3D vertical safety corridors by incorporating altitude as an additional dimension. This allows the system to provide safety assurances in the vertical domain even when horizontal positioning precision is degraded, effectively trading spatial dimensions to maintain overall safety.
3Reliability
If vertical profile is modified to avoid obstacles, then safety is improved, but flight efficiency deteriorates
Solution Approach 1:
The system dynamically adjusts vertical profiles based on real-time position updates and obstacle proximity. Rather than using fixed, conservative altitude restrictions, the system continuously optimizes vertical paths to maintain the minimum necessary clearance from obstacles, allowing more efficient flight when conditions permit while ensuring safety when obstacles are nearby.
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
Ensures safe and accurate automatic navigation of aircraft and drones even when the GNSS signal is degraded, by dynamically modifying the flight path to avoid obstacles, thus maintaining safety and integrity of the flight corridor.
Implementation Method 1
A method implemented on board an aircraft using multi-sensor data fusion, such as a Kalman filter, to estimate a 3D position and determine safety distances
Data Source
AI summary
A method allowing an aircraft to follow a lateral path with a determined safety level. The method consists in determining a 3D corridor around a predicted path of the aircraft, based on at least one computed safety distance. If the safety corridor conflicts with at least one obstacle in a terrain and obstacle database, the vertical flight profile of the aircraft is modified in order to increase the altitude of the aircraft, to avoid obstacles while keeping lateral path constant.