Resettable Frangible Link for Manual Override of Autonomous Control
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Solution Overview
Problem
Existing control systems for devices, such as aircraft engines, lack a reliable method for operators to override autonomous control actuators and seamlessly transition back to autonomous control after manual intervention, necessitating a mechanism for physical separation and reconnection of control actuators.
Innovation Solution
A resettable frangible link system that couples a second actuator to a control lever via a rod, allowing separation from the control lever based on an applied force by a first actuator, enabling manual override and subsequent reconnection for autonomous operation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a second actuator is permanently coupled to the control lever for autonomous control, then autonomous control reliability is improved, but the ability to override autonomous control manually is worsened
Solution Approach 1:
The coupling between the second actuator and control lever is segmented into separable components: a frangible link that can break under excessive force and a reset mechanism. This allows the system to maintain reliable autonomous control during normal operation while enabling manual override when needed by breaking the frangible link connection.
Solution Approach 2:
The coupling mechanism transitions from a static permanent connection to a dynamic conditional connection. The frangible link provides a flexible coupling that maintains connection under normal autonomous operation forces but disconnects when manual override forces exceed the frangible link's strength, allowing the system to adapt its control mode based on operational conditions.
2Ease of operation
If a frangible link is used to enable manual override, then manual override capability is improved, but the complexity of the control system is worsened
Solution Approach 1:
The override functionality is extracted as a separate mechanical feature (frangible link) rather than integrating it into the actuator or control lever themselves. This modular approach adds minimal complexity while providing clear manual override capability through a dedicated failure-mode connection element.
Solution Approach 2:
The frangible link serves as an intermediary element between the second actuator and control lever. It mediates the connection by providing a controlled failure point that enables manual override without requiring complex control systems or additional actuators, simply through its mechanical design.
3Ease of operation
If the second actuator is disconnected from the control lever, then manual control is improved, but the ability to return to autonomous control is worsened
Solution Approach 1:
The reset mechanism enables the system to self-reconnect the second actuator to the control lever without requiring external intervention or complex reassembly procedures. The reset button or mechanism automatically restores the frangible link connection, allowing the system to return to autonomous control mode through a simple self-contained action.
Solution Approach 2:
The frangible link is designed to be discarded (broken) during manual override but then recovered (reset) through a simple reset mechanism. This allows the connection to be temporarily discarded for manual control while maintaining the ability to recover and restore autonomous control functionality without permanent loss or complex reassembly.
Data Source
AI summary
Within examples, a system is described that includes a control lever for controlling operation of a device, a first actuator coupled to the control lever via a rod, and a resettable frangible link coupling a second actuator to the control lever via the rod. The resettable frangible link enables separation of coupling of the second actuator from the control lever based on an applied force to the rod by the first actuator.