LVDT Load Sensing in Stabilizer Actuators for Jam Detection
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Solution Overview
Problem
Current aircraft stabilizer actuators lack effective mechanisms to detect primary load path failures, such as mechanical jams, leading to potential structural damage and loss of control, as they rely on secondary load paths that may not activate in time to prevent excessive loads.
Innovation Solution
Incorporating a displacement feedback device, like a linear variable differential transformer (LVDT), between the primary and secondary load paths to sense relative displacement and determine primary load path loads, allowing for timely intervention by the controller to halt the actuator system before damage occurs, thereby reducing the need for additional sensors and minimizing system complexity, weight, and cost.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a displacement feedback device (LVDT) is used to detect primary load path failures, then detection capability and safety are improved, but device complexity and cost increase
Solution Approach 1:
The LVDT displacement feedback device, originally intended for position feedback, is repurposed to also detect primary load path failures by monitoring abnormal displacement patterns. This multi-functional use eliminates the need for separate detection sensors, reducing system complexity while improving reliability through early failure detection.
2Measurement precision
If additional sensors are added to detect primary load path failures, then detection precision is improved, but weight and cost increase
Solution Approach 1:
The existing LVDT sensor performs dual functions: providing displacement feedback for normal operation and detecting primary load path failures through abnormal displacement monitoring. This eliminates the need for additional dedicated detection sensors, reducing system weight while maintaining high detection precision through the same sensor infrastructure.
3Reliability
If the actuator system is halted immediately upon detecting excessive load, then structural damage is prevented, but operational time is reduced
Solution Approach 1:
The system performs preliminary detection of excessive loads through LVDT displacement monitoring before actual structural damage occurs. By detecting abnormal displacement patterns early in the failure process, the system can halt operation proactively, preventing catastrophic structural failure while minimizing operational disruption through timely intervention.
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 enables early detection of primary load path failures, preventing structural damage by halting the actuator system when excessive loads are sensed, reducing the risk of mechanical failure and ensuring safer operation by limiting output loads effectively.
Implementation Method 1
Incorporating a displacement feedback device, like a linear variable differential transformer (LVDT), between the primary and secondary load paths to sense relative displacement
Data Source
AI summary
An actuator assembly includes a primary load path for tightly coupling an actuated surface to a reference structure, and a secondary load path having a backlash portion for coupling the actuated surface to the reference structure with backlash, wherein the secondary load path is unloaded during an operative state of the primary load path and loaded during a failure state of the primary load path. A first sensor is configured to sense relative displacement between a portion of the primary load path and a portion of the secondary load path. A controller is operatively coupled to the first sensor, the controller configured to determine a load on the primary load path based on relative displacement sensed by the first sensor.