Multi-Rotor Thrust Limit Control for Stable Directional Flight
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Solution Overview
Problem
Aircraft stability control is limited when the thrust demand of its rotors exceeds their capability limit, particularly during disturbances or when maintaining altitude, as existing systems struggle to adjust directional movement effectively.
Innovation Solution
A method to adjust the desired thrust demand of each rotor by accounting for the excess beyond its capability limit, with algorithms to determine and apply differences based on maximum and minimum thrust limits, ensuring stable directional control while prioritizing altitude when necessary.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the thrust demand of the rotors is increased to maintain stability or lateral position during disturbances, then the aircraft stability is improved, but the thrust capability limit is exceeded which limits stability control
Solution Approach 1:
The patent dynamically adjusts the collective thrust demand of all rotors based on real-time comparison with thrust capability limits. When the maximum thrust demand exceeds the thrust capability limit, the system reduces the collective thrust demand by the exceedance amount, enabling adaptive response to changing flight conditions and disturbances while maintaining stability control authority.
Solution Approach 2:
The patent implements a feedback mechanism where the desired thrust demands of individual rotors are continuously compared against the thrust capability limit. The system calculates the exceedance amount and feeds this information back to adjust the collective thrust demand, creating a closed-loop control system that maintains stability while respecting physical constraints.
2Adaptability or versatility
If the thrust demand is collectively adjusted to maintain directional movement ability, then the pitch, roll, and turning abilities are improved, but the individual rotor thrust demands must be reduced
Solution Approach 1:
The patent merges the thrust demand adjustments across all rotors by applying a collective reduction based on the maximum exceedance. Instead of adjusting individual rotors independently, the system combines their demands and applies a unified adjustment that maintains the relative thrust distribution needed for directional control while ensuring no rotor exceeds its capability limit.
Solution Approach 2:
The patent changes the thrust demand parameter collectively for all rotors based on the calculated exceedance amount. By adjusting the collective thrust demand parameter rather than individual rotor parameters, the system maintains the ability to pitch, roll, and turn while ensuring all rotors operate within their capability limits.
3Speed
If the thrust demand exceeds the thrust capability limit, then the aircraft can respond more aggressively to disturbances, but the stability control is limited
Solution Approach 1:
The patent performs preliminary action by comparing desired thrust demands against capability limits before executing the thrust commands. By calculating the exceedance amount in advance and adjusting the collective thrust demand proactively, the system prevents instability while maintaining the ability to respond quickly to disturbances through the adjusted thrust commands.
Data Source
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AI summary
A method of adjusting a directional movement ability in an aircraft having two or more rotors includes receiving (132) a desired thrust demand for each rotor of the two or more rotors, comparing (134) the desired thrust demands to determine a maximum thrust demand, determining (136) whether the maximum thrust demand exceeds a maximum thrust limit of the two or more rotors, and adjusting (138) each desired thrust demand based on whether the maximum thrust demand exceeds the maximum thrust limit to provide an adjusted thrust demand for each rotor of the two or more rotors. Each rotor is operated based on a respective adjusted thrust demand.