Shock Strut Sensor Fusion for Objective Hard-Landing Detection
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Conventional hard-landing detection systems in aircraft are subjective and unreliable, leading to unnecessary inspections or missed structural damage, as they rely on pilot declarations, resulting in inefficiencies and resource wastage.
Innovation Solution
A hard-landing detection system for aircraft that integrates sensors and a controller to objectively assess landing events by measuring parameters such as stroke profile, oil and gas pressures, vertical loads, and sink-rate, comparing them against predetermined thresholds to determine if a landing is hard.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If pilot declaration is used to determine hard-landing events, then the detection method is simple to implement, but the reliability of detection is poor
Solution Approach 1:
The patent replaces the subjective human judgment system with an automated electronic detection system that uses sensors to measure objective parameters (vertical acceleration, stroke profile, sink rate) and compares them against predetermined thresholds. This substitution of mechanical/electronic measurement for human declaration resolves the contradiction by providing reliable, objective detection while maintaining ease of implementation through automated threshold comparison logic.
Solution Approach 2:
The system implements feedback by continuously monitoring landing parameters through sensors and automatically comparing measured values against predetermined thresholds to determine whether a hard-landing event occurred. This closed-loop feedback mechanism eliminates subjectivity while maintaining simple operation, as the system self-determines the landing classification based on objective criterion.
2Reliability
If objective parameter measurement is implemented, then the detection reliability is improved, but the device complexity increases
Solution Approach 1:
The patent leverages existing multi-functional shock strut components that already perform suspension and energy absorption functions. By integrating sensor capabilities into these existing structures, the system achieves hard-landing detection without adding completely new hardware systems. The shock strut itself serves multiple functions: mechanical support, energy absorption, and now serves as a mounting structure for detection sensors.
Solution Approach 2:
The system merges the detection function with the existing shock strut assembly by integrating sensors into the shock strut structure. Rather than adding separate detection equipment, the measurement components are combined with the suspension system, reducing overall system complexity while maintaining reliable detection capability.
3Measurement precision
If multiple sensors are integrated, then the measurement precision is improved, but the device complexity increases
Solution Approach 1:
The patent segments the measurement function into distinct sensor components, each responsible for measuring a specific parameter (vertical acceleration, stroke profile, sink rate). This segmentation allows for targeted, precise measurement of individual parameters while keeping each sensor's design and implementation relatively simple. The segmented approach to measurement contributes to overall measurement precision.
Solution Approach 2:
The system uses multiple sensors that are already integrated into the shock strut assembly, leveraging the multi-functional nature of the shock strut structure. The sensors utilize the existing shock strut environment and structural components, reducing the complexity that would arise from completely independent sensor systems.
4Loss of energy
If subjective pilot declaration is used, then inspection resources are wasted, but structural damage may go unnoticed
Solution Approach 1:
The system performs preliminary detection of hard-landing events during the landing itself by measuring parameters in real-time and comparing against thresholds. This preliminary action determines whether subsequent inspection is necessary, preventing unnecessary inspections when no damage occurred while ensuring inspection happens when damage may have occurred. The predetermined thresholds are established in advance to guide this preliminary assessment.
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
Provides accurate and timely detection of hard landings, reducing the need for unnecessary inspections and improving the reliability of structural assessments.
Implementation Method 1
a trapped volume of gas is compressed as the shock strut is axially compressed, and a volume of oil is metered through an orifice. The gas acts as an energy storage device, such as a spring
Implementation Method 2
Shock struts also dissipate energy by passing the oil through the orifice so that as the shock absorber is compressed or extended, its rate of motion is limited by the damping action from the interaction of the orifice and the oil
Data Source
Figure 1
Figure 2
Figure 3
AI summary
A method of determining whether a landing event of an aircraft is hard may comprise: receiving, by a controller (230) via a stroke position sensor (116), a stroke profile as a function of time for a shock strut; receiving, by the controller via a gas pressure sensor (110), a gas pressure in a gas chamber of the shock strut; receiving, by the controller via a wheel speed sensor (120), a wheel speed of a tire in a landing gear assembly; calculating, by the controller, multiple time dependent functions based on the stroke profile of the shock strut, based on the gas pressure, a shock strut temperature, and the wheel speed; and comparing, by the controller, the multiple time dependent functions to respective predetermined thresholds to determine whether the landing event is hard.