Brake Actuator Zero Torque Position Detection
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Solution Overview
Problem
Aircraft brake systems face challenges in accurately determining the zero torque position of brake actuators, leading to potential delays in brake engagement and safety risks due to insufficient current or malfunctioning position detection systems.
Innovation Solution
A brake actuator system comprising a ball screw, ball nut, ram, position sensor, and processor that commands the ball nut to translate towards a brake stack, detects the furthest forward position, and determines the zero torque position by retracting a predetermined distance, using maximum current and position sensors like resolvers or linear variable differential transformers to ensure accurate positioning.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Speed
If the brake actuator translates the ball nut to the furthest forward position using maximum current, then the brake engagement speed is improved, but the position detection accuracy deteriorates due to insufficient current or malfunctioning position detection systems
Solution Approach 1:
The system performs a preliminary action by retracting the ball nut a predetermined distance from the furthest forward position to determine the zero torque position. This preliminary positioning action establishes a reference point that enables accurate position detection before actual brake engagement, resolving the contradiction between fast engagement and accurate positioning.
Solution Approach 2:
The position detection system provides feedback about the ball nut position to the control system. By using this feedback to detect the zero torque position through the retraction method, the system can accurately determine the reference position even when operating at maximum current, thereby maintaining position detection accuracy while achieving rapid brake engagement.
2Productivity
If the brake actuator translates the ball nut quickly toward the brake stack, then the productivity is improved, but the reliability deteriorates due to potential position detection malfunctions
Solution Approach 1:
The system performs a preliminary positioning action by retracting the ball nut to determine the zero torque position before normal brake operation. This preliminary establishment of a known reference position ensures reliable position detection for subsequent brake actuations, maintaining reliability while enabling fast productivity.
Solution Approach 2:
The system applies preliminary anti-action by retracting the ball nut from the furthest forward position to counteract potential position detection errors. This retraction creates a controlled condition where the zero torque position can be reliably determined, preventing position detection malfunctions from compromising system reliability during high-speed operation.
3Measurement precision
If the system determines the zero torque position by retracting the ball nut from the furthest forward position, then the position detection accuracy is improved, but the time consumption increases
Solution Approach 1:
The zero torque position determination through retraction is performed as a preliminary action during system initialization or maintenance periods, not during normal brake operation. This separates the time-consuming accurate positioning task from the time-critical brake engagement task, maintaining both accuracy and operational speed.
Solution Approach 2:
The retraction-based zero torque position determination can be performed periodically or at scheduled intervals rather than continuously. This periodic execution minimizes time loss while ensuring position detection accuracy is maintained when needed, balancing the trade-off between measurement precision and time consumption.
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
This solution minimizes delays in brake engagement by accurately determining the zero torque position, reducing safety risks and ensuring rapid brake system actuation, even in cases of insufficient current or position detection malfunctions.
Implementation Method 1
a brake actuator comprising a ball screw, a ball nut coupled to the ball screw
Implementation Method 2
The position sensor may be a resolver
Implementation Method 3
the position sensor may be at least one of a linear variable differential transformer or a linear encoder
Data Source
AI summary
A brake actuator system may comprise a brake actuator comprising a ball screw, a ball nut coupled to the ball screw, and a ram coupled to a ram end of the ball nut; a position sensor coupled to the brake actuator; a processor in electronic communication with the brake actuator and the position sensor; and a tangible, non-transitory memory configured to communicate with the processor, the tangible, non-transitory memory having instructions stored thereon that, in response to execution by the processor, cause the processor to perform operations. The operations may comprise commanding the brake actuator to translate the ball nut in a first direction toward a brake stack; detecting the pusher reaching a furthest forward position; and commanding the brake actuator to translate the ball nut in a second direction opposite the first direction for a predetermined retraction distance.