Brake Control Unit Runway Friction Estimation
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Solution Overview
Problem
Aircraft braking systems face challenges in accurately assessing runway surface conditions, particularly in detecting the coefficient of friction, which can lead to skidding due to inappropriate braking pressure on varying runway surfaces like icy or wet runways, necessitating real-time estimation for safe landing operations.
Innovation Solution
A brake control unit (BCU) in the aircraft detects braking events, calculates aircraft deceleration using inertial sensors, and estimates the runway coefficient of friction based on deceleration, aerodynamic drag force, and thrust reverse force, generating a friction map with GPS location coordinates to adjust braking force and inform airport personnel of surface conditions.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Speed
If high braking pressure is applied to reduce aircraft speed during landing, then stopping distance is reduced, but the risk of wheel skidding increases on low-friction runway surfaces
Solution Approach 1:
The braking system dynamically adjusts braking pressure based on real-time runway friction conditions detected during the braking event. The BCU modulates brake force continuously rather than applying fixed pressure, allowing optimal speed control without skidding on varying surface conditions
Solution Approach 2:
The system uses feedback from wheel speed sensors and inertial sensors to monitor actual braking performance and detect skid conditions. This feedback loop allows the BCU to adjust braking pressure in real-time to prevent skidding while maintaining effective deceleration
2Speed
If braking force is increased to improve stopping performance, then aircraft deceleration is enhanced, but runway surface assessment accuracy deteriorates due to skid detection difficulty
Solution Approach 1:
The system performs preliminary runway friction assessment during the spin-up phase before full braking is applied. By evaluating wheel acceleration during this initial phase when skidding is less likely, the system obtains accurate friction data before high braking forces are engaged
Solution Approach 2:
The system uses partial braking information from multiple phases of the landing rollout, not just full braking. By combining data from spin-up, moderate braking, and skid detection phases, the system achieves accurate friction estimation while maintaining effective deceleration
3Reliability
If real-time runway condition monitoring is implemented to improve safety, then skid prevention capability is enhanced, but system complexity increases due to multiple sensors and calculations
Solution Approach 1:
The brake control unit performs multiple functions: it controls braking pressure for deceleration, monitors wheel speed for anti-skid protection, calculates runway friction coefficient, and provides runway condition mapping. This multi-functionality reduces the need for separate dedicated systems while enhancing safety
Solution Approach 2:
The system combines data from wheel speed sensors, inertial sensors, and brake pressure sensors into a unified control algorithm within the BCU. By merging these measurement functions and processing them through integrated calculations, the system achieves comprehensive runway assessment without requiring separate complex subsystems
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 risk of skidding by dynamically adjusting braking force and provides real-time runway condition data, enhancing safety and maintenance awareness for subsequent landings.
Implementation Method 1
The aircraft deceleration is calculated by an inertial sensor in the brake control unit (BCU)
Implementation Method 2
estimating, by the BCU, a runway coefficient of friction in response to detecting the skid condition, wherein the runway coefficient of friction is based on the aircraft deceleration, an aerodynamic drag force of the aircraft, and a thrust reverse force of the aircraft
Data Source
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AI summary
Systems and methods for assessing runway conditions are disclosed. The system may comprise a brake control unit (310) having an internal inertial sensor (320). The brake control unit (310) may be configured to calculate a runway coefficient of friction to assess surface conditions of the runway. The brake control unit (310) may monitor braking in an aircraft to detect a skid condition. In response to detecting the skid condition, the brake control unit (310) may calculate an aircraft deceleration of the aircraft with the inertial sensor (320). The brake control (310) unit may estimate the runway coefficient of friction based on the aircraft deceleration, an aerodynamic drag force of the aircraft, and a thrust reverse force of the aircraft (1).