Aircraft Brake Actuator With Virtual Pressure Sensing Redundancy
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Solution Overview
Problem
Existing aircraft braking systems are vulnerable to simultaneous failure due to reliance on a single hydraulic power source, and pressure sensors are prone to failure, leading to potential system inoperability.
Innovation Solution
An actuator with dual hydraulic connections and separate pressure sensors, combined with a virtual pressure sensing device, monitors and controls hydraulic pressure using a monitoring controller and command controller, and applies a degraded operating mode upon detecting sensor or pump malfunctions.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If a single hydraulic power source is used for both brakes, then the braking system structure is simplified, but the reliability deteriorates because a hydraulic leak can make both brakes inoperative simultaneously
Solution Approach 1:
The braking system is divided into two independent hydraulic circuits, with each brake having its own dedicated hydraulic power source and control mechanism. This segmentation ensures that a failure in one circuit does not affect the other, resolving the reliability issue while maintaining structural simplicity through modular design
Solution Approach 2:
Each brake circuit is given locally optimized quality with dedicated pressure sensors and control valves specific to each brake. The first brake has its own pressure sensor and control valve, and the second brake has its own pressure sensor and control valve, allowing independent monitoring and control that enhances reliability without significantly increasing overall system complexity
2Measurement precision
If pressure sensors are used to monitor hydraulic pressure, then the control precision is improved, but the reliability deteriorates because sensor failure can render the system inoperative
Solution Approach 1:
The system uses homogeneous pressure sensing approaches with both sensors measuring hydraulic pressure in the same manner and providing data to identical control algorithms. This allows the control system to process information from either sensor interchangeably, ensuring that if one sensor fails, the other can maintain full system functionality without requiring different measurement methods
Solution Approach 2:
The system implements a redundant copy of the pressure sensing and control functionality, where the second pressure sensor and its associated control valve provide a backup copy of the monitoring and control function. This copying strategy ensures that if the primary sensor fails, the system can continue operating using the redundant sensor copy
3Reliability
If redundant pressure sensors and controllers are implemented, then the failure tolerance is improved, but the device complexity increases
Solution Approach 1:
The control architecture is segmented into two independent control loops, each with its own controller that can independently manage its associated brake and pressure sensor. This segmentation allows the system to tolerate sensor or controller failures in one loop while maintaining full functionality in the other, achieving high failure tolerance without requiring a fully integrated complex control system
Solution Approach 2:
Each controller is designed with universal functionality to handle multiple tasks: monitoring pressure from its dedicated sensor, controlling its associated brake, and potentially taking over control of the other brake if needed. This multi-functionality reduces the need for specialized components for each function, thereby limiting the increase in device complexity while maintaining high reliability
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
Enhances failure tolerance by preventing complete system failure through redundant pressure monitoring and adaptive control, ensuring continued functionality even if one or more sensors fail.
Implementation Method 1
a first pressure sensor (41) arranged on the second hydraulic connection (35) and measuring a first supply pressure (PCOM)
Implementation Method 2
a second pressure sensor (51) arranged on the second hydraulic connection (35) and measuring a second supply pressure (PMON)
Implementation Method 3
a pump (15) connected to a first hydraulic connection (30) and to a second hydraulic connection (35) in order to deliver hydraulic fluid from the first hydraulic connection (30) to the second hydraulic connection (35)
Data Source
AI summary
An actuator provided with a pump connected to a first hydraulic connection connected to a reservoir and to a second hydraulic connection. A command controller communicates with a first pressure sensor arranged on the second hydraulic connection and measuring a first supply pressure. A monitoring controller communicates with the command controller and a second pressure sensor arranged on the second hydraulic connection and measuring a second supply pressure. A virtual pressure sensing device is provided with a verification instrument transmitting at least one verification signal carrying an operating parameter of the pump to the command controller and to the monitoring controller in order to identify a failure of the actuator and consequently apply a degraded operating mode.