Multi-Mode Autobrake Control System for Aircraft
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Solution Overview
Problem
Current aircraft brake control systems experience slowed responsiveness and filtering issues during non-skid conditions due to increased filtering of brake pressure and wheel speed signals, which is not necessary and can hinder performance during stable braking.
Innovation Solution
A multi-mode autobrake control system that employs an antiskid filter and a nominal filter, along with a filter switch and tuning modules, to determine the appropriate filtering and tuning based on the braking conditions, allowing for faster signal processing and disturbance tracking during stable braking.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If increased filtering is applied to brake pressure and wheel speed signals during skid conditions, then the reliability of skid control is improved, but the responsiveness and speed of the braking system during non-skid conditions deteriorates
Solution Approach 1:
The system dynamically switches between two filtering modes (antiskid filter and nominal filter) based on the operating condition detected by the antiskid controller. During skid conditions, the antiskid filter with higher filtering is applied to ensure reliability. During non-skid conditions, the nominal filter with lower filtering is applied to maintain fast responsiveness. This dynamic adaptation resolves the contradiction by adjusting the filtering level according to the actual braking state.
Solution Approach 2:
The system changes the filtering parameters (filter bandwidth and cutoff frequency) based on the operating mode. The antiskid filter uses a first bandwidth suitable for skid conditions, while the nominal filter uses a second bandwidth suitable for non-skid conditions. By changing the filtering parameters according to the detected condition, the system achieves both high reliability during skids and high responsiveness during normal braking.
2Stability of the object's composition
If increased filtering is applied to wheel speed signals, then the stability of signal processing during skid conditions is improved, but the disturbance tracking capability during non-skid conditions deteriorates
Solution Approach 1:
The system dynamically selects the appropriate filter based on the operating condition. During skid conditions, the antiskid filter provides stable signal processing by heavily filtering the noisy wheel speed signals. During non-skid conditions, the nominal filter provides precise disturbance tracking by minimally filtering the signals, allowing the system to detect and respond to small disturbances accurately.
Solution Approach 2:
The system applies different filtering qualities to different operating conditions. The antiskid filter provides high stability but lower precision, while the nominal filter provides high precision but less stability. By matching the filter quality to the specific operating condition (skid or non-skid), the system optimizes both stability and precision where they are most needed.
3Device complexity
If a single filtering mode is used for all braking conditions, then the device complexity is reduced, but the adaptability to different braking conditions deteriorates
Solution Approach 1:
The filtering system is segmented into two distinct filtering modes: the antiskid filter for skid conditions and the nominal filter for non-skid conditions. Each filter is optimized for its specific operating condition. The antiskid controller detects the operating condition and selects the appropriate filter, effectively segmenting the filtering function to improve adaptability without requiring a completely complex adaptive filter design.
Solution Approach 2:
The brake control unit serves multiple functions by incorporating both filtering modes and the ability to switch between them. The same brake control unit handles both skid control and normal braking control, and the same unit switches between different filtering modes based on the operating condition. This multi-functionality provides adaptability to different conditions while avoiding the need for separate dedicated systems.
Data Source
AI summary
A system for multi-mode autobrake control may comprise a wheel speed sensor and a BCU electrically coupled to the wheel speed sensor. A tangible, non-transitory memory may be configured to communicate with the BCU and may have instructions stored thereon that, in response to execution by the BCU, cause the BCU to perform operations comprising receiving a wheel speed signal from the wheel speed sensor, inputting the wheel speed signal into an antiskid filter and a nominal filter, calculating an estimated aircraft deceleration rate, and determining an autobrake pressure command based on the estimated aircraft deceleration rate.