Electromechanical Brake Actuator Zero-Touch Control for Low-Force Accuracy
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Solution Overview
Problem
Existing aircraft electromechanical brake systems face unpredictability in force control at lower commanded forces due to noise in load cell signals from long wire lengths.
Innovation Solution
The proposed brake system includes an electromechanical brake actuator with a ball screw that retracts to a zero-touch point (ZTP) determined by the controller using position sensors and load cell data, allowing for precise control regardless of force control or position control modes.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If load cell signals are used for brake force measurement and feedback, then accurate force control is achieved, but noise in load cell signals from long wire lengths causes unpredictability at lower commanded forces
Solution Approach 1:
The patent extracts the brake force measurement function from the load cell signal and implements it through alternative means (motor current sensing, position feedback, and control mode selection). This removes the problematic long wire length noise source while maintaining the essential measurement capability needed for accurate force control.
Solution Approach 2:
The patent changes the measurement parameter from direct load cell force signals to alternative parameters such as motor current, position feedback, and calculated force estimates. This parameter substitution eliminates the noise issue associated with long wire lengths while preserving the ability to achieve accurate force control through the controller's processing capabilities.
2Measurement precision
If the ball screw is retracted to the zero-touch point, then force control accuracy is improved, but additional control complexity is introduced
Solution Approach 1:
The patent implements preliminary action by pre-determining the zero-touch point position and storing it in memory. This preliminary setup eliminates the need for complex real-time calculations during operation, as the controller simply retrieves the pre-calculated ZTP value and uses it for ball screw retraction control, thereby reducing operational complexity while maintaining accuracy.
Solution Approach 2:
The system performs self-service by automatically determining and storing the zero-touch point position during initialization or calibration phases. The controller autonomously calculates the ZTP based on position feedback and force measurements, then uses this stored information for subsequent control operations, eliminating the need for manual intervention or complex ongoing computations.
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 enhances the predictability and accuracy of brake force application, improving the smooth operation of the braking system during taxi and landing by effectively managing noise in load cell signals.
Implementation Method 1
an electromechanical brake actuator comprising a ball screw configured to extend to exert a force on the pressure plate
Implementation Method 2
the position sensor is at least one of a resolver, tachometer, or Hall sensor
Data Source
AI summary
A brake system is disclosed herein. The brake system includes a pressure plate, an end plate, a plurality of rotating discs positioned between the pressure plate and the end plate, an electromechanical brake actuator controller, and an electromechanical brake actuator including a ball screw configured to extend to exert force on the pressure plate, the electromechanical brake actuator operatively coupled to the electromechanical brake actuator controller. Responsive to receiving a command from the electromechanical brake actuator controller, the electromechanical brake actuator is configured to retract the ball screw away from the pressure plate to at least a zero-touch point.