Hybrid Low-Speed Flight Control for Brownout Landing Stability
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Solution Overview
Problem
Brownout and whiteout conditions caused by rotor downwash reduce flight visibility during helicopter landing and take-off, leading to safety risks due to obscured visual references and potential collisions with ground obstacles.
Innovation Solution
A hybrid low-speed flight control system that transitions between translational rate command (TRC) and linear acceleration command (LAC) based on controller displacement and groundspeed, allowing seamless control without manual switches, using a rotor system with blades and an aircraft computer to process pilot inputs and generate appropriate commands for the rotor system.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the helicopter uses traditional flight control in brownout conditions, then the pilot can operate the aircraft, but the pilot loses visual references leading to loss of awareness and potential accidents
Solution Approach 1:
The patent introduces an intermediary system (augmented reality display and hybrid control system) that mediates between the pilot and the degraded visual environment. The AR display provides synthetic visual references, while the hybrid control system translates pilot inputs into appropriate control commands, allowing the pilot to maintain situational awareness without direct visual contact with the ground.
Solution Approach 2:
The patent replaces traditional mechanical flight control with a hybrid control system that combines mechanical inputs with electronic processing. The system substitutes direct visual feedback with electronically generated visual references and replaces manual control mode selection with automatic mode transition based on flight conditions.
2Adaptability or versatility
If the helicopter transitions between TRC and LAC control modes manually, then the pilot can adapt to different flight conditions, but the complexity of manual mode switching increases pilot workload and potential for error
Solution Approach 1:
The hybrid control system performs self-service by automatically determining the appropriate control mode (TRC or LAC) based on real-time flight conditions and controller displacement. The system eliminates the need for manual mode selection, reducing pilot workload while maintaining adaptability to different flight phases through automatic mode transition logic.
Solution Approach 2:
The control system dynamically transitions between TRC and LAC modes based on flight conditions and controller position. The system is designed to be dynamic rather than static, allowing seamless adaptation to changing flight conditions without requiring pilot intervention or complex manual switching procedures.
3Measurement precision
If the helicopter uses TRC control at high groundspeed, then the aircraft can be maneuvered precisely, but the control becomes less effective when groundspeed exceeds TRC threshold speed
Solution Approach 1:
The patent changes the control parameter from rate command (TRC) to acceleration command (LAC) based on groundspeed conditions. When groundspeed exceeds the TRC threshold, the system automatically switches to LAC mode, where controller displacement commands acceleration rather than direct velocity changes, maintaining control effectiveness across the full range of operating speeds.
Data Source
AI summary
An exemplary method for controlling low speed flight of an aircraft having a controller receiving pilot input includes transitioning from a translational rate command (TRC) to a linear acceleration command (LAC) when the controller is displaced above a control transition displacement (CTD), and while in LAC holding speed when the controller is relaxed to CTD.