VTOL Trajectory Switching for Memory-Constrained Flight Control
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Solution Overview
Problem
Current aircraft motion planning systems face challenges in managing memory requirements and ensuring safety in complex environments, particularly for autonomous aviation navigation, as they require high memory and complex forward planning to react to unforeseen events, which limits their ability to be certified for passenger-carrying aircraft.
Innovation Solution
A method for a multi-rotor VTOL aircraft that calculates finite nominal and emergency trajectories beforehand, allowing real-time switching between them using a transition planning algorithm based on sensor data, with defined transition intervals and a maneuver library, ensuring manageable memory usage and deterministic behavior.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If complete mission pre-planning with high degree of branching and fine temporal/spatial discretization is used to react to changing circumstances, then the ability to react to unforeseen events is improved, but memory requirements increase linearly or exponentially
Solution Approach 1:
The patent segments the flight mission into discrete phases (takeoff, cruise, landing) and represents trajectories as sequences of motion primitives rather than continuous functions. This segmentation allows the system to manage complex flight paths through compositional planning, where each phase can be planned and stored independently, reducing overall memory requirements while maintaining adaptability.
Solution Approach 2:
The patent pre-calculates and stores a library of motion primitives and trajectory segments before flight operations. These pre-computed building blocks (including nominal and emergency trajectories) are stored in database structures that can be efficiently queried and combined during flight, eliminating the need to compute complex trajectories in real-time while keeping memory usage manageable through structured storage.
2Adaptability or versatility
If optimization- or sampling-based planning algorithms are executed on the flight platform to provide flexibility, then adaptability is improved, but transparency and deterministic behavior are lost
Solution Approach 1:
The patent implements a hybrid planning architecture where the overall mission structure remains static and deterministic (pre-planned phases and transitions), but the selection and parameterization of motion primitives within each phase can be dynamically adjusted based on real-time sensor feedback. This allows the system to maintain deterministic guarantees at the mission level while achieving adaptability through dynamic primitive selection.
Solution Approach 2:
The patent introduces a structured database and query system as an intermediary between the pre-planned trajectory library and the real-time flight controller. This intermediary layer provides deterministic access patterns and transparent data retrieval, ensuring that while the underlying planning algorithms may be complex, the interface to the flight control system remains predictable and verifiable.
3Reliability
If forward planning with all possible flight states known in advance is used to ensure safety and verifiability, then reliability is improved, but the complexity of pre-planning increases
Solution Approach 1:
The patent applies different levels of planning detail to different flight phases and spatial regions. Nominal trajectories provide high-level guidance for safe flight paths, while motion primitives provide detailed local control instructions for specific maneuvers. This local differentiation allows the system to ensure safety through pre-planned nominal paths while reducing overall pre-planning complexity by only detailed-planning where necessary.
Solution Approach 2:
The patent pre-calculates emergency trajectories and backup plans alongside nominal trajectories during the pre-planning phase. These cushioning trajectories are stored in the database and can be activated if the nominal plan becomes unsafe, providing beforehand protection against unforeseen events without requiring complex real-time decision-making, thus maintaining reliability while managing pre-planning complexity.
Data Source
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AI summary
In particular, a method for controlling an aircraft of a specific type, especially a multirotor VTOL aircraft with preferably electrically driven rotors, is proposed, wherein a) before a flight, a finite number of nominal trajectories (NT) for the aircraft and a finite number of emergency trajectories (CT) arranged around the nominal trajectories (NT) are calculated and stored in a database available on board the aircraft; b) before a flight, a finite number of type-specific, permissible flight maneuvers of the aircraft are pre-planned and stored as a maneuver library in the database; c) optionally, before a flight, a number of discrete flight planes with different flight altitudes are defined and stored in the database;d) during a flight, the database is accessed by means of a computer-aided transition planning algorithm in order to switch between the nominal trajectories (NT) and the emergency trajectories (CT), and optionally between the defined flight planes, depending on a state of the aircraft detected by sensors and using the pre-planned flight maneuvers, and to control a trajectory follower and/or a flight control system of the aircraft accordingly.