Frangible Link Override for Autonomous Control Levers
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Solution Overview
Problem
Existing control systems lack the ability for an operator to seamlessly override autonomous control actuators and revert to manual control, particularly in scenarios where autonomous control may fail or is undesired.
Innovation Solution
A resettable frangible link mechanism is introduced to couple and decouple actuators to a control lever, allowing manual override by applying a force, ensuring safe separation and reconnection of control actuators.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If a single actuator is permanently coupled to the control lever, then the control system is simple and reliable, but the operator cannot override autonomous control
Solution Approach 1:
The coupling mechanism is segmented into a permanent first coupling (first actuator to control lever) and a removable second coupling (second actuator to control lever) connected via a frangible link. This segmentation allows the system to switch between autonomous and manual control modes by enabling the second actuator to be disconnected when override is needed.
Solution Approach 2:
The second actuator can be extracted or removed from the control lever coupling through the frangible link mechanism. When the frangible link fails due to excessive force or command conflict, the second actuator is automatically extracted from the control system, allowing manual override while maintaining the permanent first actuator connection.
2Ease of operation
If the frangible link is designed to break under high force, then manual override is enabled, but the link may break during normal operation
Solution Approach 1:
The frangible link is designed with localized failure characteristics at specific weak points while maintaining overall structural integrity. The link has predetermined break points with controlled strength that are weaker than the rest of the structure, ensuring it only fails when force exceeds the designed threshold during genuine override scenarios rather than during normal operation.
Solution Approach 2:
The system incorporates force threshold detection and gradual force application mechanisms that prevent sudden excessive forces from reaching the frangible link during normal operation. Control software and mechanical dampers cushion normal operational forces below the break threshold, while still allowing the link to break when genuine override force is applied.
3Adaptability or versatility
If two separate control systems are used, then autonomous and manual control are independent, but the system complexity increases
Solution Approach 1:
Both the first actuator (manual control) and second actuator (autonomous control) are merged to operate on the same control lever through the frangible link coupling mechanism. This merging allows both control systems to share the same mechanical interface while maintaining independent operational capability, reducing overall system complexity compared to having completely separate control levers.
Solution Approach 2:
The control lever serves multiple functions: it can be controlled by the first actuator for manual operation, by the second actuator for autonomous operation, or by direct operator input when the frangible link breaks. This multi-functionality allows a single control lever to handle both autonomous and manual control modes, eliminating the need for separate control mechanisms.
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.