Brake Friction Estimation for Wheel Load Balance Control
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Solution Overview
Problem
Aircraft braking systems face issues due to varying coefficients of friction among brakes, leading to unexpected yaw and load imbalance, which can cause controllability problems and premature wear of brakes.
Innovation Solution
The system uses an estimated coefficient of friction (μ) for prognostics and health management (PHM) to monitor brake assemblies, comparing decelerations and brake force ratios to identify anomalies, and adjusts brake commands to maintain balanced deceleration across all wheels.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If the brake controller applies the same brake force to all wheels, then the control system is simple and easy to operate, but the varying coefficients of friction among brakes cause load imbalance and premature wear
Solution Approach 1:
The patent applies local quality by adjusting brake force individually for each wheel based on its specific friction coefficient characteristics. The brake controller modifies the brake command for each wheel assembly separately, allowing each brake to operate under optimized conditions rather than applying uniform force to all wheels.
Solution Approach 2:
The system changes the brake force parameter dynamically based on detected friction coefficient variations. By monitoring wheel deceleration and comparing it to expected values, the system identifies brakes with abnormal friction coefficients and adjusts their brake force accordingly to achieve balanced load distribution.
2Reliability
If the system monitors brake performance continuously, then brake issues are detected early improving safety, but the system complexity and measurement requirements increase
Solution Approach 1:
The patent implements feedback by continuously monitoring wheel deceleration during braking operations and comparing actual performance to expected performance. The brake controller uses this feedback to detect friction coefficient variations and identify potential brake issues, enabling proactive maintenance while using existing sensor data.
Solution Approach 2:
The system uses existing wheel speed sensors and brake controller data to monitor brake performance without requiring additional specialized measurement devices. The brake controller itself performs the analysis and detection functions, leveraging available system resources rather than adding separate monitoring hardware.
3Speed
If brake force is increased to improve stopping performance, then deceleration capability improves, but brakes with varying friction coefficients experience premature wear and load imbalance
Solution Approach 1:
The system applies local quality by individually adjusting brake force for each wheel based on its friction coefficient characteristics. Wheels with lower friction coefficients receive higher brake force commands, while wheels with higher friction coefficients receive lower commands, ensuring balanced load distribution and extending brake life while maintaining overall deceleration performance.
Data Source
AI summary
A method for controlling brake assemblies of a vehicle is provided. Receiving a deceleration of each wheel assembly of a plurality of wheel assemblies of the vehicle. Comparing the deceleration of each wheel assembly to an average deceleration of the plurality of wheel assemblies. Responsive to one or more of the deceleration of each wheel assembly of one or more wheel assemblies being outside a predetermined range of the average deceleration of the plurality of wheel assemblies, reporting a warning message to a maintenance crew to inspect one or more brake assemblies associated with the one or more wheel assemblies.