Flight Control Actuation Force Fight Mitigation
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Solution Overview
Problem
In aircraft flight control systems, the active-active operational configuration of actuators can lead to force fights due to independent tolerances in actuators, position sensors, control electronics, and mechanical components, resulting in torsion moments and stress on flight control surfaces, which increases weight and cost to mitigate worst-case stress and fatigue.
Innovation Solution
The implementation of a flight control surface actuation system that includes differential pressure sensors, user interface sensors, and a control unit to process signals and generate substantially equal actuator commands, mitigating force fights between hydraulically-operated actuators by sensing differential fluid pressure, user interface movement, and flight control surface position.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If active-active operational configuration is used, then reliability is improved, but force fights occur between actuators
Solution Approach 1:
The control unit receives feedback signals from position sensors and differential pressure sensors that monitor the state of each actuator. Based on this feedback, the control unit dynamically adjusts the actuator commands to ensure equal force distribution and eliminate force fights between actuators while maintaining the active-active configuration.
Solution Approach 2:
The system changes the operational parameters of the actuators by using differential pressure sensors to monitor and adjust the hydraulic pressure supplied to each actuator. This parameter adjustment ensures that all actuators operate with equal force, preventing force fights while maintaining redundancy.
2Device complexity
If active-active operational configuration is used, then device complexity is reduced, but stress and fatigue on flight control surfaces increase
Solution Approach 1:
Position sensors provide continuous feedback on the flight control surface position and actuator states. The control unit uses this feedback to coordinate all active actuators, ensuring they move the control surface synchronously and eliminate torsion moments that would otherwise cause stress and fatigue.
Solution Approach 2:
The control unit acts as an intermediary between multiple actuators and the flight control surface. It processes sensor inputs and generates coordinated commands that synchronize actuator operations, preventing force fights and reducing stress on the flight control surface structure.
3Object-generated harmful factors
If actuator tolerances are reduced, then force fights are mitigated, but manufacturing cost increases
Solution Approach 1:
Differential pressure sensors provide real-time feedback on the actual force being applied by each actuator. The control unit uses this feedback to compensate for manufacturing tolerances in actuators and components, adjusting commands to equalize force distribution without requiring tighter manufacturing tolerances.
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
This solution effectively mitigates force fights between actuators in the active-active operational configuration without increasing the weight of flight control surfaces, thereby reducing stress and fatigue, and eliminating the need for redundant management systems.
Implementation Method 1
Each DP sensor is configured to sense a differential fluid pressure across a hydraulically-operated actuator and supply a differential pressure signal representative of the sensed differential fluid pressure
Implementation Method 2
The position sensor is configured to sense flight control surface position and supply a flight control surface position signal representative of the sensed flight control surface position
Implementation Method 3
Each user interface sensor is configured to sense movement of a user interface and supply a position command signal representative of the sensed movement
Implementation Method 4
Each actuator is configured, upon receipt of the actuator command, to move a flight control surface to a position
Data Source
AI summary
A system and method of mitigating a force fight between hydraulically-operated actuators that are coupled to a single flight control surface is provided. The differential fluid pressure across each hydraulically-operated actuator is sensed. The position of a user interface is sensed using a plurality of user interface position sensors. Flight control surface position is sensed using one or more position sensors. The sensed differential pressures, the sensed user interface positions, and the sensed flight control surface position are used to generate a plurality of substantially equal actuator commands.