Automatic Heading Control for Tiltrotor Lateral Force Mitigation
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Solution Overview
Problem
Rotorcraft face challenges in controlling excessive lateral forces, particularly during high winds, which can exceed the physical limitations of the control system and swashplate, leading to loss of control authority and unsafe flight conditions.
Innovation Solution
A system and method that monitor lateral control signals, compare them to preset limits, and automatically adjust the rotorcraft's heading to reduce excessive lateral forces by disabling manual control and using a heading control module to calculate and implement a heading error, thereby reducing the impact of external lateral forces.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the lateral swashplate control is used to produce lateral force to oppose cross wind, then the aircraft can hover with zero lateral attitude, but the lateral force may exceed the physical limitations of the control system and swashplate
Solution Approach 1:
Instead of using lateral swashplate control to oppose cross wind (conventional approach), the system inverts the approach by using differential collective rotor control to generate the lateral force, while keeping the swashplate within its physical limitations. This reverses the control methodology to avoid exceeding swashplate capabilities.
Solution Approach 2:
The system changes the control parameter from lateral cyclic swashplate input to differential collective rotor input. By altering which control parameter is used to generate lateral force, the system avoids the physical limitations of the swashplate while maintaining effective crosswind compensation.
2Reliability
If so much control system tilt is used to oppose lateral force, then the lateral force is countered, but there is not enough control left in the control system to fly or land the rotorcraft
Solution Approach 1:
The system inverts the control strategy by using differential collective control instead of lateral cyclic control to oppose lateral forces. This preserves lateral control authority in the swashplate system for maneuvering and landing, while still providing effective crosswind compensation through the alternative control mechanism.
Solution Approach 2:
The control system is segmented into two independent control channels: differential collective control for lateral force generation and lateral cyclic swashplate control for attitude control and maneuvering. This segmentation allows each channel to operate within its optimal range without compromising overall control versatility.
3Ease of operation
If manual heading control is used during excessive lateral force, then the pilot maintains control, but the lateral force exceeds control system limitations leading to loss of control authority
Solution Approach 1:
The system continuously monitors lateral acceleration and provides feedback to the control system. When excessive lateral force is detected, the feedback triggers automatic activation of the alternative control method (differential collective control), allowing the system to respond to changing conditions without pilot intervention while maintaining control authority.
Solution Approach 2:
The control system performs self-service by automatically detecting excessive lateral forces and switching to the alternative control methodology without requiring pilot awareness or action. The system monitors its own state and autonomously adjusts control strategy to prevent loss of control authority.
Data Source
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AI summary
One embodiment of the present invention is a method for automatically reducing the effect of a component of an external force that is laterally incident on a rotorcraft. A signal of the rotorcraft indicative of and proportional to the component is monitored. An absolute value of the signal and a preset high limit are compared. If the absolute value is greater than the preset high limit, manual heading control of the rotorcraft is disabled and the heading of the rotorcraft is adjusted with respect to the external force so as to decrease the lateral component of the external force experienced by the rotorcraft.