Coordinated Aileron-Rudder Control for Flexible Mode Mitigation
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Solution Overview
Problem
Aircraft-pilot coupling events occur due to unwanted aircraft motions caused by interactions between the pilot and the aircraft, leading to instabilities in the closed-loop feedback control system, affecting passenger comfort and aircraft control.
Innovation Solution
A method and system that mitigate the excitation of structural flexible modes of an aircraft by executing commands for ailerons and rudders in conjunction, where the commands are tailored based on characteristics such as frequency, magnitude, altitude, speed, weight, and fuel quantity to counteract the effects of these modes, thereby reducing the risk of inducing aircraft-pilot coupling events.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If aileron commands are executed to control aircraft roll, then aircraft maneuverability is improved, but structural flexible modes may be excited causing aircraft-pilot coupling instabilities
Solution Approach 1:
The control system applies preliminary anti-action by detecting aileron commands and automatically generating counteracting rudder commands before the flexible mode excitation can cause instability. The rudder command is designed to produce a yawing moment that opposes the rolling moment from ailerons, preventing the excitation of structural flexible modes and the resulting aircraft-pilot coupling instabilities.
Solution Approach 2:
The rudder acts as an intermediary control surface between the pilot's aileron input and the aircraft's roll response. By introducing rudder commands as a mediating action, the system modifies the overall control effect to eliminate harmful flexible mode excitations while preserving the desired roll maneuverability through coordinated aileron-rudder operation.
2Reliability
If rudder commands are applied to counteract flexible mode excitation, then control system stability is improved, but additional control surface activity increases energy consumption
Solution Approach 1:
The system applies partial action by generating rudder commands only when aileron commands are detected that would excite flexible modes. The rudder command magnitude is precisely tuned to provide just enough counteracting yawing moment to stabilize the system, avoiding excessive control surface deflections and minimizing unnecessary energy consumption while maintaining control stability.
3Reliability
If coordinated aileron and rudder commands are executed, then aircraft-pilot coupling instabilities are reduced, but control system complexity increases
Solution Approach 1:
The control system employs feedback by continuously monitoring aileron command inputs and automatically generating corresponding rudder commands. The feedback loop detects when aileron commands are present and triggers the appropriate rudder counter-action, creating a closed-loop control mechanism that reduces aircraft-pilot coupling instabilities without requiring complex manual coordination procedures.
Data Source
AI summary
Systems and methods for controlling a fixed-wing aircraft during flight are disclosed. The aircraft comprises first and second flight control surfaces of different types. The method comprises determining that a pilot command of the first flight control surface will excite a structural flexible mode of the aircraft and then executing the pilot command of the first flight control surface in conjunction with a command of the second flight control surface to mitigate the effect of the excitation of the structural flexible mode of the aircraft.