Compliant Stops for Aircraft Force Sensor Overload Protection
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Solution Overview
Problem
Existing aircraft piloting devices face challenges in accurately measuring forces during certification, as the high certification forces can damage or destroy the force sensors, and ensuring simultaneous contact of mechanical stops with the force sensor membrane is difficult, leading to erroneous force readings.
Innovation Solution
The piloting device incorporates a force sensor with a compliant material in the mechanical stops, ensuring symmetrical load distribution and preventing damage to the force sensor during certification, while maintaining accurate force measurements.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If the force sensor is optimised for operational force values, then measurement precision for normal piloting is improved, but the sensor becomes vulnerable to damage from certification forces
Solution Approach 1:
A compliant stop element is introduced as an intermediary between the rigid structure and the force sensor membrane. This compliant element absorbs the excessive certification forces through deformation, preventing direct transmission of damaging forces to the sensor while maintaining accurate force measurement capability during normal operation.
Solution Approach 2:
The compliant stop element is pre-installed in the mechanism to provide cushioning protection before certification testing occurs. This preventive measure ensures that when maximum certification forces are applied during testing, the compliant element will deform to absorb the excess force and protect the force sensor from damage.
2Strength
If rigid stops are used to limit rotation amplitude, then mechanical strength is improved, but simultaneous contact of multiple stops with the membrane becomes difficult to ensure, leading to measurement errors
Solution Approach 1:
The stop element's material parameter is changed from rigid to compliant. This allows the stop to deform and adapt to slight variations in manufacturing and assembly, ensuring that multiple stops can simultaneously contact the membrane with equal force distribution, thereby eliminating measurement errors while maintaining sufficient mechanical strength.
Solution Approach 2:
The compliant stop element introduces local flexibility at the contact point with the membrane, while the overall mechanical structure remains strong. This localized compliance allows each stop to independently adjust its contact force, ensuring simultaneous and symmetrical loading of the membrane without compromising the global structural integrity.
3Reliability
If the piloting member is subjected to maximum certification forces, then certification requirements are met, but the force sensor may be damaged or destroyed
Solution Approach 1:
The compliant stop element is installed in advance to provide protective cushioning during certification testing. When maximum certification forces are applied, the compliant element deforms to absorb the excessive force, preventing direct transmission to the force sensor and avoiding damage while still allowing the system to undergo required certification testing.
Solution Approach 2:
The compliant stop acts as a protective intermediary between the certification loading system and the force sensor. It mediates the force transmission by deforming under extreme loads, allowing certification forces to be applied safely without damaging the sensitive force measurement device.
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 allows the piloting device to withstand certification forces without damaging the force sensor, ensuring precise and accurate force measurements, thereby enhancing the reliability and safety of the aircraft piloting system.
Implementation Method 1
The at least one pair of stops comprises a compliant material
Implementation Method 2
at least one force sensor measuring at least one component of the forces in the piloting device, by deformation of at least one deformable sensing element of the force sensor
Data Source
AI summary
A piloting device for piloting an aircraft includes a piloting member suitable for being actuated by a pilot, a mechanism for mounting and guiding in rotation the piloting member about at least one rotation axis with respect to a frame, at least one force sensor connected between the piloting member. The mechanism includes at least one sensing element configured to produce a signal upon deformation indicative of a force applied to the piloting member. The force sensor comprises at least one pair of bearing surfaces. The device also includes at least one pair of stops configured to limit the angular amplitude of rotation of the piloting member with respect to the frame on abutment of the at least one pair of bearing surfaces with at least one pair of stops. The stops or at least one of the bearing surfaces comprises a compliant material.