Landing Gear Strut Pressure Filtering for Aircraft Weight Accuracy
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Solution Overview
Problem
Existing aircraft weight and balance systems face inaccuracies due to frictional forces in landing gear struts, leading to distorted pressure measurements that are not corrected for seal wear or environmental changes, which affect the accuracy of weight determination.
Innovation Solution
Implementing software algorithms that continuously measure and filter strut pressures in conjunction with 3-axis accelerations and groundspeed to identify and remove distorted pressure measurements, using time-stamped data to correct for seal friction and environmental factors, thereby improving the accuracy of weight and center of gravity determination.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If landing gear strut pressure is measured to determine aircraft weight, then weight measurement capability is provided, but measurement precision deteriorates due to seal friction distortions
Solution Approach 1:
The system continuously monitors landing gear strut pressure and uses feedback algorithms to detect and correct for seal friction distortions. By comparing pressure readings during different phases of gear operation (extension, retraction, stationary), the system identifies friction-induced errors and applies compensatory calculations to determine accurate aircraft weight.
Solution Approach 2:
The patent introduces computational algorithms as an intermediary between the raw pressure measurement and the final weight determination. These algorithms process the pressure data, separate the friction component from the weight-bearing component, and produce a corrected weight measurement that eliminates the harmful effect of seal friction.
2Reliability
If landing gear seal friction is present, then weight measurement is complicated by dynamic friction changes, but the system can still provide weight indication
Solution Approach 1:
The system dynamically adapts to changing friction conditions by continuously monitoring pressure readings during gear operation. Rather than using fixed friction compensation values, the system adjusts correction parameters in real-time based on observed pressure behavior, accounting for variations in seal friction due to temperature, wear, and operational conditions.
Solution Approach 2:
The patent changes the parameters used for weight calculation based on the operational state of the landing gear. Different correction algorithms are applied depending on whether the gear is extending, retracting, or stationary, and based on the observed pressure-rate-of-change characteristics, the system selects appropriate friction compensation parameters.
3Measurement precision
If static friction (breakout friction) is overcome before strut compression, then initial weight transfer is delayed, but weight measurement can still be obtained after movement begins
Solution Approach 1:
The system performs preliminary detection of breakout friction events by monitoring for characteristic pressure patterns that indicate seal seizure or static friction overcoming. When such events are detected, the system proactively applies friction correction algorithms to compensate for the delayed weight transfer, ensuring accurate measurement despite the time delay.
Solution Approach 2:
The patent identifies and skips over the transient period during which breakout friction delays weight transfer. By detecting the characteristic pressure signature of seal release and rushing through the correction calculation during this transient phase, the system obtains accurate weight measurements without being adversely affected by the temporary delay in weight transfer.
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 solution provides more accurate aircraft weight measurements by reducing the influence of seal friction and environmental changes, enhancing the precision of weight and balance calculations.
Implementation Method 1
the rubbing action between the telescopically sliding components of the landing gear strut, being its outer cylinder and inner piston, is often referred to as 'frictional forces'
Implementation Method 2
The aircraft weight is transferred to and is supported by the pressures contained within the landing gear struts
Implementation Method 3
the weight of an aircraft rests upon 3-pockets of compressed gas
Data Source
AI summary
The methods and systems provide for increasing the accuracy of aircraft weight and center of gravity determination through the use of filtered strut pressure measurements. Aircraft vertical and horizontal accelerations are determined as the aircraft is taxiing, and used to identify and reduce the number of significantly distorted pressure measurements, to allow the lesser distorted pressure measurements to be averaged, and a lesser number of distorted pressure measurements to be averaged; further identifying the aircraft in near-neutral acceleration and strut pressure values near-neutral of strut seal friction distortions. Pressure sensors, accelerometers, and an inclinometer are mounted in relation to landing gear struts to monitor, measure and record strut pressure as related to strut telescopic movement, rates of strut telescopic movement and aircraft vertical and horizontal accelerations; experienced by landing gear struts, as the aircraft proceeds through typical ground and taxi operations.