Multipivot Control Stick Linkages for Jam-Tolerant Fly-By-Wire
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Solution Overview
Problem
Fly-by-wire aircraft systems face challenges in maintaining control redundancy and resilience against single-point failures in human machine interfaces (HMIs) such as control sticks, particularly in transitioning to single-pilot operations.
Innovation Solution
A multipivot user interface device with independently rotatable linkages and a sensing arrangement to measure orientation angles, allowing continued operation even if one linkage is jammed, by compensating with the other linkage to maintain control.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If single pilot operations are utilized to reduce cockpit complexity, then device complexity is reduced, but reliability deteriorates due to loss of redundant control systems
Solution Approach 1:
The control stick is divided into multiple independent linkages (first linkage, second linkage, third linkage) that can operate independently. Each linkage has its own pivot points and sensing elements, allowing the system to segment the control function across multiple redundant mechanical paths while maintaining a single pilot interface.
Solution Approach 2:
The system incorporates redundant linkages and sensing arrangements before failure can occur. If one linkage becomes jammed or fails, the other linkages are already in place and can be activated to compensate, providing beforehand cushioning against control system failure.
2Reliability
If redundant linkages are added to prevent single point of failure, then reliability is improved, but device complexity increases
Solution Approach 1:
Multiple linkages are merged into a single integrated control stick assembly that presents a unified interface to the pilot. The first, second, and third linkages are combined in such a way that they appear as one cohesive control device, reducing the perceived complexity while maintaining redundant internal mechanical paths.
Solution Approach 2:
The control stick is designed with multi-functionality where the same physical device can operate through multiple mechanical paths. The linkages share common pivot points and can be actuated by the same pilot input, allowing one control device to serve multiple redundant functions simultaneously.
3Reliability
If mechanical linkages are made independent to prevent jamming, then reliability is improved, but ease of operation deteriorates due to increased control complexity
Solution Approach 1:
The control system is designed to be dynamic in its operation. Under normal conditions, the linkages operate together in a coordinated manner that feels natural to the pilot. When a failure occurs, the system dynamically adapts by allowing alternative linkages to compensate, maintaining ease of operation through automatic reconfiguration rather than requiring pilot intervention.
Solution Approach 2:
The control stick system is self-servicing in that it automatically compensates for its own failures without requiring pilot awareness or action. The redundant linkages and sensing arrangements are configured to self-diagnose and self-correct by automatically switching to alternative mechanical paths when a linkage becomes jammed or fails.
Data Source
AI summary
Fly-by-wire vehicle systems and related user interface devices are provided for controlling operation of a vehicle, such as an aircraft. An exemplary user interface includes a first linkage and a second linkage coupled to the first linkage. The first linkage is actuatable about a first pivot point and the second linkage is actuatable about a second pivot point independent of actuation of the first linkage about the first pivot point. The user interface includes a sensing arrangement configurable to obtain a first orientation of the first linkage with respect to a first reference orientation associated with the first pivot point, obtain a second orientation of the second linkage with respect to a second reference orientation associated with the second pivot point, and determine an input command based at least in part on the first orientation and the second orientation.