Hydraulic Actuator Position Locking for Failure-Hold Control
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Solution Overview
Problem
Conventional hydraulic actuator systems in helicopters tend to revert to a fail-safe position during electrical failures, such as fully retracted or extended, rather than maintaining the last commanded position, which is undesirable for maintaining flight control parameters.
Innovation Solution
The implementation of a hydraulic actuator system with a position-lock controller that hydraulically decouples the actuator controller from the retract or extend cavities in response to a failure, such as a power failure, to maintain the actuator in the last commanded position by locking hydraulic pressures within the cavities.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the actuator is designed to automatically position in a fail-safe position during electrical failure, then the system reliability is improved, but the flight control parameters cannot be maintained
Solution Approach 1:
The position lock controller is pre-configured to detect electrical failures and automatically lock the actuator in its last commanded position before any unwanted movement can occur. This preliminary action prevents the actuator from reverting to fail-safe positions while maintaining flight control parameters.
Solution Approach 2:
A position lock controller is introduced as an intermediary component between the actuator controller and the hydraulic actuator. This intermediary detects failures and hydraulically decouples the actuator controller, preventing automatic positioning while maintaining the last commanded position to preserve flight control parameters.
2Adaptability or versatility
If the actuator controller remains hydraulically coupled during failure, then the actuator can be repositioned, but the actuator moves to unwanted fail-safe positions
Solution Approach 1:
The system dynamically transitions from a hydraulically coupled state (allowing repositioning) to a hydraulically decoupled state (locking position) upon detecting failure. The position lock controller adjusts the hydraulic coupling status in real-time, maintaining stability by locking the actuator in its last commanded position while preventing unwanted movement to fail-safe positions.
3Stability of the object's composition
If the position-lock controller hydraulically decouples the actuator controller from the cavities, then the actuator position is locked, but the device complexity increases
Solution Approach 1:
The position lock function is extracted as a separate, dedicated controller that independently manages hydraulic decoupling. This extracted component simplifies the overall system architecture by separating the position locking function from the main actuator controller, making the system easier to understand and maintain despite the added complexity.
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 allows the actuator to remain in the last commanded position during failures, preventing unwanted movement and ensuring stability, even under great loads, thereby enhancing flight control and reducing the risk of damage to the system.
Implementation Method 1
the actuator controller is configured to control a hydraulic pressure within each of the retract cavity and the extend cavity to control actuation of the hydraulic actuator
Data Source
Figure 1A~1B
Figure 2~4
Figure 5
AI summary
Hydraulic actuator systems of aircraft are described. The hydraulic actuator systems include a hydraulic actuator (101, 201, 301) having a housing and piston therein. The piston includes a piston head separating the housing into a retract cavity and an extend cavity. An actuator controller (112) is hydraulically coupled to the retract cavity by a first hydraulic line and hydraulically coupled to the extend cavity by a second hydraulic line and configured to control a hydraulic pressure within each of the retract cavity and the extend cavity to control actuation of the hydraulic actuator (101, 201, 301). A position-lock controller is arranged along at least one of the first hydraulic line and the second hydraulic line, the position-lock controller is configured to hydraulically decouple the actuator controller (112) from at least one of the retract cavity and the extend cavity.