Force Sensor Assembly with Quadruple Redundancy for Aircraft Inceptors
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Solution Overview
Problem
Existing aircraft inceptor force sensors lack redundancy and accuracy in measuring strain, particularly in fly-by-wire systems, which can lead to failures in translating pilot inputs due to mechanical jamming or cross-talk between pitch and roll channels, compromising flight safety.
Innovation Solution
A force sensor apparatus with a flexible sensing element and dual sensor systems (primary and redundant) that utilize strain gauges on orthogonal arms to provide quadruple redundancy, minimizing cross-talk and ensuring accurate strain measurement verification, allowing for independent verification of pilot inputs and fail-safe operation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a single force sensor system is used to measure pilot inputs, then the device complexity is reduced, but the reliability is insufficient due to lack of redundancy
Solution Approach 1:
The sensor system is segmented into four independent measurement lanes (command pitch, command roll, monitor pitch, monitor roll) that separately measure different aspects of pilot input. Each lane processes strain measurements independently, providing modular redundancy without requiring a complete duplicate sensor system.
Solution Approach 2:
The monitor lanes perform preliminary verification of command lane measurements in real-time before the data is used for flight control. This preliminary action detects potential failures early, allowing the system to switch to redundant measurement paths before actual control degradation occurs.
2Measurement precision
If strain gauges are placed on flexible arms to measure pitch and roll, then the measurement precision is improved, but cross-talk between pitch and roll channels increases
Solution Approach 1:
The flexible sensing element uses an asymmetric cross-shaped geometry where the arms are oriented at specific angles to maximize sensitivity to pitch and roll moments while minimizing coupling between axes. The strain gauge placement on opposite surfaces of arms creates differential measurements that cancel out cross-talk.
Solution Approach 2:
The measurement approach transitions from planar strain measurement to three-dimensional strain analysis by placing gauges on both top and bottom surfaces of flexible arms. This dimensional approach allows separation of pitch and roll strain components through differential measurement techniques.
3Reliability
If a redundant sensor system is implemented with quadruple measurement lanes, then the reliability is improved, but the device complexity increases
Solution Approach 1:
The flexible sensing element serves multiple functions simultaneously: it provides structural support for the sensor assembly, acts as the strain-sensing element itself, and generates four independent measurement lanes from a single component. This multi-functionality reduces the number of separate components needed.
Solution Approach 2:
The patent merges the command and monitor measurement systems into a single flexible sensing element with integrated strain gauge arrays. Instead of separate sensor assemblies, both command and monitor lanes share the same physical sensing structure, reducing overall system complexity while maintaining redundancy.
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 quadruple redundancy system enhances flight safety by providing reliable strain measurements and reducing the risk of mechanical failures, ensuring accurate translation of pilot inputs into aircraft control commands, even in the event of primary sensor system failure.
Implementation Method 1
Strain gauges are disposed on top and bottom surfaces of each arm to measure compression/tension on the surface
Data Source
AI summary
A force sensor, flexible sensing element, and method for the force sensor are disclosed. The force sensor uses a flexible sense element with two flexible arms dedicated to measuring strain related to a pitch force and two flexible arms dedicated to measuring strain related to roll force. The use of two channels for each measurement provides a command lane and a monitor lane for strain measurements. Strain gauges are disposed on both the top and the bottom surfaces of each arm, thus providing two completely redundant systems. When a failure is detected in one of the systems, the redundant system can be implemented.