Electromechanical Brake Force Control Without Load Cell Feedback
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Solution Overview
Problem
Existing aircraft braking systems face challenges in maintaining accurate force control, particularly when load cell sensors fail, leading to unpredictable and potentially unsafe braking conditions.
Innovation Solution
The proposed brake system employs an electromechanical brake actuator that extends a ball screw based on the worn state of rotating discs and a stiffness curve representing force versus ball screw position, allowing for precise force application even without functional load cell sensors.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If load cell sensors are used for brake force measurement and feedback, then accurate force control is achieved, but system reliability deteriorates when sensors fail
Solution Approach 1:
The patent introduces stiffness curves as an intermediary model that mediates between the actuator position and the actual brake force. Instead of directly relying on load cell sensors, the system uses the stiffness curve (which represents the relationship between ball screw position and applied force) to calculate force from position measurements, providing a backup measurement path when sensors fail.
Solution Approach 2:
The patent changes the measurement parameter from direct force sensing (load cell) to position sensing (ball screw position) combined with a stiffness model. By measuring position and using the stiffness curve to derive force, the system maintains measurement capability without the single point of failure associated with load cell sensors.
2Measurement precision
If ball screw position is controlled based on worn state and stiffness curves, then force control accuracy is maintained, but device complexity increases
Solution Approach 1:
The patent performs preliminary action by pre-calculating and storing stiffness curves for different worn states of the brake components. These curves are generated in advance and stored in memory, so that during operation the controller can simply look up the appropriate curve based on the detected worn state without performing complex real-time calculations.
Solution Approach 2:
The patent makes the control system dynamic by adapting the stiffness curve selection based on the detected worn state of the brake components. The system transitions between different stiffness curves (corresponding to different worn states) to maintain accuracy as the brake components wear over time, rather than using a fixed stiffness model.
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 enables accurate and predictable force control during braking, ensuring safe operation even in the event of load cell sensor failures, by utilizing stiffness curves to determine the appropriate ball screw position for the given worn state of the brake components.
Implementation Method 1
a ball screw positioned between the electromechanical brake actuator and the pressure plate. The electromechanical brake actuator is configured to extend the ball screw to a ball screw position to apply a requested force to the pressure plate towards the end plate
Implementation Method 2
forcing the plurality of rotating discs together in an axial direction in order to reduce a rotational speed of the plurality of rotating discs
Data Source
Figure 1A
Figure 1B
Figure 2
AI summary
A brake system is disclosed herein. The brake system includes an electromechanical brake actuator (104), a pressure plate (110), an end plate (111), a ball screw (106) positioned between the electromechanical brake actuator (104) and the pressure plate (110), and a plurality of rotating discs positioned between the pressure plate (110) and the end plate (111). The electromechanical brake actuator (104) is configured to extend the ball screw (106) to a ball screw position to apply a requested force to the pressure plate (110) towards the end plate (111) thereby forcing the plurality of rotating discs together in an axial direction in order to reduce a rotational speed of the plurality of rotating discs. The ball screw (106) is extended by the electromechanical brake actuator (104) to the ball screw position based on a worn state of the plurality of rotating discs and a stiffness curve for the electromechanical brake actuator (104) that represents force versus ball screw position for the worn state.