Rotary Wing Aircraft Hover Control Mode Switching
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Solution Overview
Problem
Current flight control systems for rotary-wing aircraft, particularly in manual and automated modes, face challenges in efficiently managing trajectory holding and heading hold across various flight phases, including low-speed and high-altitude operations, especially in difficult atmospheric and visibility conditions, where rapid adjustments are needed to avoid obstacles and maintain stability.
Innovation Solution
A method and system that utilize a rotary-wing aircraft with multiple control axes and an automatic pilot to switch between trajectory holding and heading holding modes based on longitudinal speed, allowing for precise control of ground course angle, deceleration rate, slope, and heading, enabling the aircraft to transition seamlessly from high-speed trajectory holding to low-speed hovering with heading maintenance, using predefined threshold speeds to manage flight parameters and adjust the stop position dynamically.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Stability of the object's composition
If trajectory holding mode is used at high forward speed, then the aircraft can maintain stable progression along a ground trajectory, but the control system becomes less responsive to rapid pilot adjustments needed in low-speed hovering
Solution Approach 1:
The system dynamically switches between trajectory holding and heading hold modes based on the aircraft's forward speed. At high speeds, trajectory holding provides stable automated control. When speed drops below a threshold, the system transitions to heading hold mode, giving the pilot direct control for rapid adjustments during hovering operations. This dynamic mode switching resolves the contradiction by adapting the control characteristics to the current flight phase.
2Ease of operation
If heading hold mode is used at low forward speed, then the pilot has direct control for rapid adjustments, but the aircraft cannot maintain precise ground trajectory at high speeds
Solution Approach 1:
The control system automatically transitions between heading hold and trajectory holding modes based on forward speed thresholds. During low-speed hovering, heading hold provides responsive pilot control. When the aircraft accelerates above the threshold, the system switches to trajectory holding mode to maintain precise ground track accuracy. This dynamic adaptation allows each control mode to operate in its optimal performance range.
3Device complexity
If a single control mode is used across all flight phases, then the control system is simpler to implement, but it cannot efficiently manage both high-speed trajectory holding and low-speed hovering requirements
Solution Approach 1:
The control system is segmented into distinct operational modes (trajectory holding and heading hold) that are activated based on flight conditions. A mode selection mechanism divides the flight envelope into high-speed and low-speed regimes, with each regime having its own optimized control law. This segmentation allows the system to maintain simplicity within each mode while achieving versatility across the full flight envelope through conditional switching.
Solution Approach 2:
The system uses dynamic mode switching based on forward speed to adapt control characteristics to flight phase. The transition between trajectory holding and heading hold modes is automatically triggered when speed crosses predefined thresholds. This dynamic reconfiguration enables the control system to efficiently manage both high-speed cruise and low-speed hovering without requiring a completely different control architecture for each phase.
4Stability of the object's composition
If automated autopilot control is used, then flight stability is improved, but pilot ability to make rapid manual adjustments is reduced
Solution Approach 1:
The system dynamically adjusts the level of automation based on flight phase. During high-speed flight, the trajectory holding mode provides strong automated control for stability. During low-speed hovering, the heading hold mode transitions control authority to the pilot, enabling rapid manual adjustments. This dynamic adjustment of control authority allows the system to maximize both automated stability and pilot responsiveness depending on operational requirements.
Data Source
AI summary
The present invention relates to a method and a system for putting into hover (1) for a rotary-wing aircraft (10). A first mode of operation allows, when the longitudinal speed UX of said aircraft (10) is greater than a first threshold speed Vthreshold1, to approach a stopping position S with a trajectory held relative to the ground, the flight instructions of an autopilot (15) being a ground track angle TKground, a deceleration rate Ga of the forward speed Va of said aircraft (10), a slope P and a heading ψ.A second mode of operation allows, when said longitudinal speed UX is less than a second threshold speed Vthreshold2, to achieve a hover at said stop position S with a heading hold, said flight instructions being said longitudinal speed UX, a lateral speed VY, a vertical speed WZ and said heading ψ, said speeds UX, VY and WZ being brought progressively back to zero speed after any action by a pilot of said aircraft (10).