Fly-by-wire Jam Mitigation via Force-Based Control Switching
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Solution Overview
Problem
Fly-by-wire aircraft systems face challenges in maintaining control when a pilot cockpit controller or its associated components become jammed, leading to loss of control surfaces and potential safety risks, as existing systems cannot completely take over command from the jammed controller.
Innovation Solution
The implementation of a fly-by-wire system that detects jams by comparing actual pilot input force with expected values, switching to generate commands based on applied force rather than position, allowing continued control of flight surfaces even if the cockpit controller is jammed, using force sensors and position sensors to determine expected positions and generate appropriate commands.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a fly-by-wire system uses position sensors to command actuation systems, then normal control operation is achieved, but control is lost when the cockpit controller becomes jammed
Solution Approach 1:
The system dynamically switches between two control modes: normal position-based control and jam-detection force-based control. The control mode is not fixed but adapts based on real-time monitoring of pilot input characteristics, allowing the system to maintain reliability under varying operational conditions including jam scenarios
Solution Approach 2:
The system changes the control parameter from position-only to force-based control when a jam is detected. By monitoring the relationship between expected and actual pilot input forces, the system transitions to using force magnitude as the primary control signal, enabling continued control authority even when the controller position is fixed
2Reliability
If the system switches to force-based control when jam detected, then control is maintained, but abnormal input forces are required
Solution Approach 1:
The system continuously monitors pilot input force and compares it against expected force values for given positions. This feedback mechanism detects jams by identifying discrepancies between expected and actual force relationships, enabling automatic mode switching without requiring the pilot to manually detect or declare a jam condition
Solution Approach 2:
The system automatically detects and responds to jam conditions without requiring pilot intervention or control transfer procedures. The fly-by-wire system self-manages the transition from position-based to force-based control, eliminating the need for abnormal manual operations or coordination between multiple pilots
3Measurement precision
If position sensors are used for control commands, then precise control is achieved, but control becomes ineffective when controller position is fixed
Solution Approach 1:
The system introduces force sensors as an intermediary measurement device that captures pilot intent even when position sensors become ineffective due to controller jamming. The force sensors serve as a backup measurement modality, translating physical pilot effort into control signals when the primary position-based measurement fails
Data Source
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AI summary
Systems and methods for jam mitigation in aircraft fly-by-wire systems are described herein. An example method of controlling an aircraft with a fly-by-wire system includes determining a current position of a pilot cockpit controller of the fly-by-wire system, determining an amount of pilot input force applied to the pilot cockpit controller, determining an expected pilot input force value that corresponds to the current position of the pilot cockpit controller, and, if the amount of pilot input force applied exceeds the expected pilot input force value by a threshold, generating a pilot command based on the amount of pilot input force applied and not the current position of the pilot cockpit controller.