Rotorcraft Descend-to-Hover FBW Control for Stable Mode Transitions
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Solution Overview
Problem
Rotorcrafts face challenges in transitioning smoothly between different flight modes due to tightly coupled flight parameters, requiring complex control inputs that increase pilot workload, especially during descents and hovers, as opposed to fixed-wing aircraft where control inputs are less interdependent.
Innovation Solution
A fly-by-wire (FBW) system that schedules a descend plane with altitude and ground speed profiles, allowing the rotorcraft to autonomously descend and decelerate, intercepting the planned path and maintaining altitude until reaching a hover, thereby reducing pilot workload and stabilizing the aircraft.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If a rotorcraft uses traditional control systems with tightly coupled flight parameters, then the control system can maintain stability, but the pilot workload increases during transitions between flight modes
Solution Approach 1:
The control system automatically adjusts flight parameters during mode transitions without requiring continuous pilot input. The system monitors its own state and makes corrective adjustments to collective pitch, cyclic pitch, and engine power to maintain stability during transitions, effectively making the system self-regulating and reducing pilot workload.
Solution Approach 2:
The control system continuously monitors flight parameters including altitude, airspeed, and attitude, and uses this feedback to automatically adjust control surfaces and engine power. This closed-loop control ensures stable transitions between flight modes while minimizing the control inputs required from the pilot.
2Ease of operation
If a rotorcraft implements automated flight mode transitions, then pilot workload is reduced, but the complexity of the control system increases
Solution Approach 1:
The control system dynamically adapts its behavior based on the current flight mode and transition state. It adjusts control laws and parameter coupling in real-time to optimize performance during transitions, making the system more capable without requiring a completely complex redesign of the entire control architecture.
Solution Approach 2:
The control system is divided into separate functional modules that manage different aspects of flight control (collective management, cyclic management, engine power control). This modular approach allows automated transitions to be implemented in specific modules without overwhelming the entire system, managing complexity through functional segmentation.
3Stability of the object's composition
If flight parameters are tightly coupled in a rotorcraft, then the aircraft maintains stability, but smooth transitions between flight modes become difficult
Solution Approach 1:
The control system dynamically changes parameter coupling relationships during transitions. It selectively decouples or recouples parameters based on the transition phase, allowing smooth transitions while maintaining stability. For example, it may temporarily reduce the coupling between collective pitch and engine power during a transition to allow independent adjustment.
4Reliability
If complex control inputs are required during flight mode transitions, then flight stability is maintained, but pilot workload increases
Solution Approach 1:
The control system automatically performs the complex control adjustments needed during transitions without requiring the pilot to manually input multiple control commands. The system monitors its own state and makes the necessary adjustments to collective pitch, cyclic pitch, and engine power autonomously, maintaining stability while keeping the pilot's workload low.
Data Source
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AI summary
A method for controlling a rotorcraft (101; 401; 501; 601), including receiving, by a fly-by-wire (FBW) system of the rotorcraft, a pilot input that initiates an automated descend-to-hover flight mode, scheduling, by the FBW system, a descend plane (405, 406; 506; 606) for bringing the rotorcraft to a hover, and autonomously descending and decelerating the rotorcraft (101; 401; 501; 601) according to the descend plane (405, 406; 506; 606) in response to determining that the rotorcraft has entered the automated descend-to-hover flight mode and until the rotorcraft reaches a hover or the rotorcraft (101; 401; 501; 601) exits the automated descend-to-hover flight mode.