Aircraft Terrain Avoidance Using Reduced-Order Closed-Loop Models

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Solution Overview

Problem

Existing flight control computing systems for aircraft face computational complexity issues that lead to latency and delays in calculating flight trajectories to avoid terrain obstacles, especially at high speeds, due to the complexity of full-order models used for trajectory generation.

Innovation Solution

Implementing a reduced-order closed-loop model in the flight control computing system to approximate the behavior of full-order models, combined with a fade function to process command signals, allowing for faster trajectory calculation and obstacle avoidance.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Manufacturing precision

If full-order models are used for trajectory generation, then manufacturing precision and reliability are improved, but device complexity and calculation time increase

Engineering Contradiction:
Improvetrajectory calculation precisionVSAvoidcomputational complexity
Core Design Contradiction:
Manufacturing precisionVSDevice complexity

Solution Approach 1:

The patent extracts only the essential dynamic characteristics from the complex full-order aircraft model to create a reduced-order model. This selective extraction maintains the critical behavior needed for terrain avoidance while removing unnecessary computational complexity, achieving both precision and efficiency

Inventive Principle:
Principle #2Taking out (Extraction)

Solution Approach 2:

The patent transforms the full-order model into a reduced-order model by changing the mathematical parameters and order of the system. This parameter transformation reduces computational complexity while preserving the essential dynamic response characteristics needed for accurate trajectory prediction and obstacle avoidance

Inventive Principle:
Principle #35Parameter changes

2Manufacturing precision

If full-order models are used for trajectory generation, then trajectory accuracy is improved, but loss of time increases

Engineering Contradiction:
Improvetrajectory accuracyVSAvoidcalculation latency
Core Design Contradiction:
Manufacturing precisionVSLoss of time

Solution Approach 1:

The patent extracts the essential dynamic behavior from the computationally intensive full-order model, creating a streamlined reduced-order model that maintains trajectory accuracy for terrain avoidance while dramatically reducing calculation latency suitable for real-time high-speed operation

Inventive Principle:
Principle #2Taking out (Extraction)

Solution Approach 2:

The reduced-order model is pre-designed and validated to provide accurate trajectory predictions without requiring complex real-time calculations. This preliminary preparation allows the system to quickly generate accurate flight paths when obstacles are detected, eliminating calculation delays

Inventive Principle:
Principle #10Preliminary action

3Reliability

If full-order models are used for trajectory generation, then reliability is improved, but productivity decreases

Engineering Contradiction:
Improveflight control reliabilityVSAvoidtrajectory generation speed
Core Design Contradiction:
ReliabilityVSProductivity

Solution Approach 1:

The patent extracts the critical reliability-preserving elements from the full-order model while removing computationally heavy components. The resulting reduced-order model maintains sufficient accuracy and reliability for terrain avoidance operations while enabling rapid trajectory generation at high speeds

Inventive Principle:
Principle #2Taking out (Extraction)

Solution Approach 2:

The patent creates a dynamically appropriate model that adapts to the specific needs of terrain avoidance operations. The reduced-order model provides real-time responsiveness and rapid trajectory generation while maintaining the reliability needed for safe high-speed flight through obstacle-prone areas

Inventive Principle:
Principle #15Dynamics

Data Source

PatentEP4242777B1Controlling aircraft to avoid terrain obstacles using reduced order closed loop models
Publication Date: 2025.06.25 LOCKHEED MARTIN CORP
  • EP4242777B1 patent drawingFigure 1
  • EP4242777B1 patent drawingFigure 2
  • EP4242777B1 patent drawingFigure 3A

AI summary

This disclosure relates to apparatuses, systems, and methods for controlling an aircraft. A computing system may identify a first command signal received via a flight control at a time point to control navigation of the aircraft through an environment. The computing system may attenuate the first command signal using a fade function over a time window relative to the time point to generate a second command signal. The computing system may input the second command signal to a model to generate predicted paths for the aircraft through the environment over the time window. The computing system may determine that at least one predicted path intersects with an obstacle in the environment during the time window. The computing system may generate a location to which to navigate the aircraft to avoid the obstacle. The computing system may perform an action to direct the aircraft to the location.