Switchable Pilot Control Forces for Aircraft Trim Stability
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Solution Overview
Problem
Existing aircraft control systems face challenges in maintaining robustness against unintended pilot intervention while allowing for direct pilot intervention options, often resulting in either sensitivity to unintended control actions or loss of trim point during manual control.
Innovation Solution
A device with a trim point and return forces that allows for reduced manual control forces, maintaining the original trim point, and enabling the autopilot to exert considerable forces, featuring a trim coupling that can decouple the return spring from the control unit, and a trim control unit that stores and restores the trim point.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If moderate artificial breakout forces are used to enable sensitive manual control, then ease of operation is improved, but reliability deteriorates due to high sensitivity to unintended intervention
Solution Approach 1:
The breakout force generation is segmented into two independent sources: a return spring providing moderate breakout forces for manual control, and a trim motor providing additional artificial forces for autopilot support. This segmentation allows each component to be optimized independently - the return spring ensures sensitive manual control while the trim motor provides robust autopilot forces without increasing the base breakout force level.
Solution Approach 2:
The trim coupling acts as an intermediary mechanism that selectively connects or disconnects the trim motor from the control system. When engaged, it allows the autopilot to exert additional forces through the control system; when disengaged, it isolates the autopilot forces from the manual control path, preventing unintended intervention while maintaining sensitive manual control.
2Power
If increased artificial breakout forces are used to support autopilot forces, then the autopilot force range is improved, but ease of operation deteriorates due to reduced manual control sensitivity
Solution Approach 1:
The force generation system is segmented into a return spring for baseline breakout forces and a trim motor for additional autopilot forces. This allows the autopilot to access increased force range through the trim motor without requiring increased breakout forces from the return spring, thereby preserving manual control sensitivity.
Solution Approach 2:
The system dynamically adjusts the total artificial forces by controlling the trim motor output based on autopilot demands. The trim motor can provide variable additional forces as needed by the autopilot, while the return spring maintains constant moderate breakout forces for sensitive manual control, achieving both high power range and ease of operation.
3Ease of operation
If the trim coupling is decoupled during manual intervention to reduce breakout forces, then ease of operation is improved, but loss of trim point information occurs
Solution Approach 1:
The trim control unit automatically monitors and stores trim point information, and the system self-restores the trim point after manual intervention by re-engaging the trim coupling. This eliminates the need for manual trim point reconfiguration while providing reduced breakout forces during manual control, simultaneously achieving ease of operation and preventing information loss.
Solution Approach 2:
The trim control unit continuously monitors the control system state and uses feedback to determine when to engage or disengage the trim coupling. This feedback mechanism ensures the trim point is preserved and restored automatically, preventing information loss while enabling ease of manual operation when needed.
4Reliability
If complete degradation of autopilot is implemented during manual intervention, then reliability is improved by preventing conflicting control actions, but extent of automation deteriorates
Solution Approach 1:
Instead of complete autopilot degradation, the system implements partial degradation by selectively managing the trim coupling engagement. The autopilot can maintain stabilizing functions while the trim coupling is disengaged during manual intervention, providing just enough autopilot action to prevent conflicting control without requiring complete deactivation. This achieves reliability improvement while preserving beneficial automation.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
The solution provides robustness against unintended pilot intervention, allowing significant autopilot force action while ensuring manual control at acceptable breakout forces and maintaining the pre-set trim point, reducing the risk of critical flight situations.
Implementation Method 1
means for generating return forces that act in the direction of the neutral position of the manual control unit
Implementation Method 2
a trim motor, by way of which the AFCS intervenes in the control system
Data Source
AI summary
A device for controlling vehicles having a manual control unit configured to influence the direction of movement of a vehicle. The manual control unit provides, in a neutral position of the manual control unit, a trim point to determine a preferred direction of movement. The device further includes a force generating device, generating at least one force acting in the direction of the neutral position of the manual control unit; a trim coupling operable to reduce the at least one force acting on the manual control unit; and a trim control unit configured to store and retain the trim point existing prior to an operation of the trim coupling.