Virtual Runway Centerline for Low Visibility Takeoff
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Solution Overview
Problem
Aircraft are restricted from taking off during low visibility conditions due to the lack of sufficient fidelity in Instrument Landing System (ILS) signals and limitations in Global Positioning System (GPS) signals, which are currently relied upon for navigation assistance during takeoffs.
Innovation Solution
A system that includes a runway centerline estimator, an Inertial Navigation System (INS) Output Filter and Fault Detector, a centerline tracking estimator, and a takeoff criteria evaluator, which generate a virtual runway centerline and provide feedback to pilots to ensure accurate alignment and deviation analysis without relying on external navigation signals, using onboard resources like inertial navigation and runway databases.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If ILS signals are used for navigation assistance during takeoff, then lateral guidance accuracy is improved, but system availability deteriorates because many airports lack ILS with sufficient fidelity
Solution Approach 1:
The patent introduces an intermediary system consisting of external cameras mounted on the aircraft to capture runway images, which are then processed by onboard image processing systems to generate virtual runway centerline guidance. This intermediary approach bridges the gap between airports without high-fidelity ILS and the need for accurate lateral guidance during low visibility takeoffs.
Solution Approach 2:
The patent replaces the reliance on complex ground-based ILS infrastructure with a self-contained aircraft-based vision system. Instead of depending on external navigation aids that require expensive airport installation and maintenance, the system uses the aircraft's own cameras and processing capabilities to provide runway centerline tracking, thereby improving system availability across all airports.
2Reliability
If GPS signals are used for navigation assistance during takeoff, then system availability is improved, but measurement precision deteriorates due to signal fidelity limitations
Solution Approach 1:
The patent merges multiple data sources including external camera images, onboard inertial navigation system (INS) data, and GPS information to create a integrated navigation solution. The image processing system processes visual runway information and combines it with INS and GPS data through sensor fusion algorithms, thereby achieving both the availability of GPS and the precision of visual runway tracking.
Solution Approach 2:
The patent creates a virtual copy of the runway environment by capturing real-time images of the runway with external cameras and processing them to generate a virtual runway centerline representation. This virtual model serves as a precise navigation reference that compensates for the inherent imprecision of GPS signals, enabling accurate lateral guidance during takeoff.
3Reliability
If onboard resources are used to generate virtual runway centerline, then dependence on external navigation aids is reduced, but device complexity increases due to additional sensors and processing requirements
Solution Approach 1:
The patent designs the external camera system to serve multiple functions: capturing runway images for centerline tracking, providing situational awareness for the pilot, and potentially supporting other navigation functions. The image processing system is also multi-functional, handling tasks such as runway detection, centerline extraction, and integration with the aircraft's existing navigation display systems, thereby justifying the added complexity through enhanced versatility.
Data Source
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AI summary
Systems and methods for takeoff assistance and analysis are provided. In one embodiment, a takeoff ground roll assist system for an aircraft comprises: a runway centerline estimator, wherein the runway centerline estimator generates a virtual runway centerline estimate for a runway based on coordinates for the runway from a runway database; an (Inertial Navigation System) INS Output Filter and Fault Detector wherein the filtering of navigation measurements from an on-board inertial navigation system, using a runway centerline start point as established by activation of a pilot operated start point sensor occurs, a centerline tracking estimator coupled to receive a filtered output of the on-board inertial navigation system from the INS output filter and fault detector and to receive the virtual centerline estimate from the runway centerline estimator, wherein the centerline tracking estimator generates a centerline tracking feedback signal that varies as a function of a difference between an aircraft look-ahead point and the virtual runway centerline; and a takeoff criteria evaluator coupled to the runway centerline estimator and the centerline tracking estimator, wherein the takeoff criteria evaluator estimates a lateral deviation between the aircraft and an actual runway centerline for the runway based on an estimated navigation error component, the runway database error component, and a centerline tracking error component.