Adaptive Noise Thresholds for Aircraft Antiskid Control
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Solution Overview
Problem
Aircraft braking systems are susceptible to false activations due to electrical noise, affecting the antiskid function and braking efficiency, particularly during landing speeds.
Innovation Solution
A skid control system that includes a brake control device, a deceleration control unit, a data repository with noise threshold values, and a brake control algorithm unit to adjust current command values based on filtered wheel speed or acceleration values, ensuring that braking pressure or force is maintained within a noise threshold, thereby preventing false activations.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If electrical noise filtering is increased to prevent false activations, then system reliability improves, but response time to actual braking events may be delayed
Solution Approach 1:
The patent implements dynamic adjustment of noise threshold values based on operating conditions (wheel speed, deceleration rate). The filtering criteria are not static but adapt in real-time to distinguish between noise at different operational states, allowing aggressive filtering only when necessary while maintaining rapid response during actual braking events.
Solution Approach 2:
The system changes the parameter of noise threshold values based on wheel speed and deceleration rate. By modifying the filtering parameters dynamically rather than using fixed thresholds, the system achieves both noise rejection and rapid response - the thresholds are relaxed when rapid change is detected (indicating real braking) and tightened during steady states (where noise is more likely).
2Measurement precision
If noise threshold values are set low to detect all braking events, then sensitivity improves, but false activations from electrical noise increase
Solution Approach 1:
The patent applies different noise threshold values for different operating conditions (different wheel speeds and deceleration rates). Instead of a uniform threshold, the system tailors the filtering criteria to local operating conditions - using stricter thresholds during steady-state operations and more permissive thresholds during dynamic braking maneuvers, thereby achieving both precision and noise rejection.
Solution Approach 2:
The system pre-establishes multiple noise threshold values corresponding to different operating conditions before actual braking occurs. By having pre-calculated thresholds ready for various wheel speed and deceleration scenarios, the system can immediately apply the appropriate filtering criteria without delay, preventing false activations while maintaining sensitivity to real events.
Data Source
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AI summary
The present disclosure provides a skid control system (300) that includes a brake control device (317) configured to convert a current command value to create a braking pressure, wherein the braking pressure is applied to a hydraulically actuated brake and/or an electrically actuated brake. A deceleration control unit (312) receives a filtered wheel speed value and/or a filtered wheel acceleration value from the wheel assembly. A brake control algorithm unit (315) retrieves a noise threshold value corresponding with the at least one of the filtered wheel speed value or the filtered wheel acceleration value. A pressure control unit (316) receives a feedback pressure from the hydraulically actuated brake and/or an electrically actuated brake, wherein the pressure control unit (316) either increases or decreases the current command value in response to a difference between the pressure command value and a feedback pressure being either less than or greater than the noise threshold value.