Feed Forward Equalization for Redundant Actuator Force Fighting
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Solution Overview
Problem
Active-active redundant actuation systems for flight control surfaces face issues with force fighting fatigue, leading to metal fatigue and premature aging due to slight differences in actuator positions, which existing technologies have not adequately addressed.
Innovation Solution
The implementation of feed-forward equalization control in conjunction with feedback equalization control across multiple redundant actuators, using a feed-forward equalization controller to anticipate and correct for force fighting, and a feedback equalization controller to respond to changes, thereby reducing the required feedback control bandwidth and enhancing stability.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If multiple actuators are used simultaneously to move a flight control surface in an active-active redundant system, then reliability is improved, but force fighting fatigue occurs due to slight differences in actuator positions leading to metal fatigue and premature aging
Solution Approach 1:
The feed-forward equalization controller pre-calculates and applies compensation commands to actuators based on their individual characteristics and expected positions. This preliminary action anticipates and corrects position deviations before they cause force fighting, thereby maintaining reliability while preventing metal fatigue and premature aging of the flight control surface
Solution Approach 2:
The feedback equalization controller continuously monitors actual actuator positions and forces, comparing them against desired values. When deviations are detected, the controller adjusts actuator commands in real-time to equalize forces, preventing force fighting fatigue while maintaining the reliability benefits of redundant actuation
2Strength
If feedback equalization control is used to respond to changes in actuator positions, then force fighting is reduced, but the required feedback control bandwidth increases reducing stability
Solution Approach 1:
By implementing feed-forward equalization control that pre-calculates compensation commands based on actuator characteristics and expected positions, the system reduces the magnitude of corrections needed from feedback control. This lowers the required feedback bandwidth while maintaining force equalization, thereby preserving system stability
Solution Approach 2:
The system optimizes feedback control parameters by adjusting bandwidth limitations based on the feed-forward compensation effectiveness. This allows the feedback controller to operate within a stable bandwidth range while still achieving force equalization, preventing oscillations and maintaining overall system stability
Data Source
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AI summary
A method and apparatus for controlling movement of a component in a system by a plurality of actuators. An operation actuation command to move the component is received. For each of the plurality of actuators, the operation actuation command is used to generate a feed-forward equalization command for the actuator, the feed-forward equalization command for the actuator is combined with the operation actuation command to provide an equalized actuation command for the actuator, and the actuator is controlled to move the component using the equalized actuation command for the actuator.