Landing Gear Wheel Deceleration Control
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Solution Overview
Problem
Current hydraulic retract braking systems for aircraft landing gear often result in undesirable noise and vibration due to delayed deceleration and despinning of wheels during retraction, leading to potential collisions with the aircraft's well and fatigue of structural components.
Innovation Solution
A modulated wheel deceleration control system that uses wheel speed sensors to actively regulate brake pressure, reducing excessive deceleration and rebound through antiskid valve modulation, ensuring wheels stop spinning before entering the well and minimizing structural stress.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If manual actuation of landing gear lever is used, then pilot control is maintained, but wheel deceleration is delayed causing collisions and noise
Solution Approach 1:
The control system automatically initiates wheel deceleration in advance based on detected landing gear retraction motion, eliminating the delay caused by manual pilot response. The system prepares and executes braking action before the wheels would otherwise collide with the well structure.
2Speed
If rapid deceleration is applied to despin wheels, then wheel speed is reduced quickly, but structural components experience fatigue and rebound occurs
Solution Approach 1:
The braking system dynamically adjusts brake pressure based on real-time wheel speed feedback. The control algorithm modulates pressure to maintain optimal deceleration rate that prevents structural fatigue while achieving timely wheel despin, avoiding both excessive force and insufficient braking.
Solution Approach 2:
Wheel speed sensors provide continuous feedback to the control system, which adjusts brake pressure accordingly. This closed-loop control prevents excessive deceleration forces that would cause structural fatigue and rebound, while ensuring wheels decelerate sufficiently before entering the well.
3Loss of time
If excessive brake pressure is applied, then wheels stop spinning faster, but rebound increases causing collision risk
Solution Approach 1:
The system applies brake pressure that is sufficient but not excessive for wheel deceleration. By using feedback control to match brake pressure to actual wheel speed, the system achieves the minimum necessary braking action to prevent collisions without creating rebound problems.
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 system effectively reduces the likelihood of wheel collisions with aircraft structures, decreases fatigue on landing gear components, and minimizes noise and vibration by precisely controlling wheel deceleration during retraction.
Implementation Method 1
A modulated wheel deceleration control system that uses wheel speed sensors to actively regulate brake pressure
Implementation Method 2
reducing excessive deceleration and rebound through antiskid valve modulation
Implementation Method 3
Hydraulic retract braking systems may be implemented to decelerate and/or despin the wheels of the landing gear
Data Source
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AI summary
Methods and apparatus for controlling landing gear retract braking are described. A controller determines wheel speed data corresponding to a speed of a wheel of a landing gear. The controller determines wheel deceleration data corresponding to a rate of change of the wheel speed data. The controller generates a first control signal in response to the wheel deceleration data being greater than a wheel deceleration threshold. The first control signal initiates a wheel deceleration regulation process, the wheel deceleration regulation process to cycle an antiskid valve between a first valve position to release brake pressure from the wheel and a second valve position to cease releasing the brake pressure from the wheel. The controller generates a second control signal in response to the wheel speed data being less than a wheel speed threshold. The second control signal terminates the wheel deceleration regulation process.