Rotorcraft Control Mode Transition Smoothing for Fly-By-Wire
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Solution Overview
Problem
Fly-by-wire systems in rotorcraft face challenges in smoothly transitioning between different control modes, leading to physical transients such as bumps or jolts during changes in control algorithms, which can affect pilot workload and passenger comfort.
Innovation Solution
The implementation of a method that transitions between translational rate command (TRC) mode and rate mode by fading out the gain of the attitude controller and decrementing the integrator value, ensuring a smooth transition by maintaining a proportional path and increasing the gain of the control path between the cyclic controller and rate control block.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If the control algorithm is changed during mode transition, then the control performance is improved, but physical transients such as bumps or jolts occur
Solution Approach 1:
The patent applies dynamics by making the controller output adjustable and time-varying during mode transitions. The controller dynamically modifies its output signal based on the transition phase, using different control laws at different times to smooth the transition between modes while maintaining control effectiveness.
Solution Approach 2:
The patent changes controller parameters during mode transitions, specifically adjusting the controller output and gain values as functions of time or transition state. This parameter modification allows the system to adapt to different operational modes while minimizing disruptive transients in the control signal.
2Reliability
If fly-by-wire systems are adopted in rotorcraft, then operational safety is improved, but system complexity increases
Solution Approach 1:
The patent introduces an intermediary smoothing mechanism between the pilot controls and the flight control system. This intermediary layer processes and smooths control signals during mode transitions, reducing the complexity burden on the overall system while maintaining safety through controlled, gradual transitions.
Solution Approach 2:
The patent applies preliminary action by preparing and smoothing control signals before actual mode transitions occur. The system anticipates mode changes and pre-adjusts controller outputs to prevent abrupt transitions, thereby simplifying the overall control architecture while enhancing safety.
3Speed
If control mode transitions are made rapidly, then response time is improved, but pilot workload increases due to noticeable changes
Solution Approach 1:
The patent uses dynamic control signal adjustment to achieve rapid mode transitions without increasing pilot workload. The controller dynamically adapts its output during transitions, maintaining smooth control characteristics that prevent noticeable changes to the pilot while still achieving fast mode switching.
Solution Approach 2:
The patent employs feedback mechanisms to monitor and adjust control signals during mode transitions. By continuously monitoring the transition process and adjusting controller outputs accordingly, the system achieves rapid transitions while maintaining ease of operation through smooth, pilot-friendly control characteristics.
Data Source
AI summary
In accordance with an embodiment, a method of operating an aircraft includes operating the aircraft in a first mode including determining an attitude based on a pilot stick signal, where a translational speed or an attitude of the aircraft is proportional to an amplitude of the pilot stick signal in the first mode; transitioning from the first mode to a second mode when a velocity of the aircraft exceeds a first velocity threshold; and operating the aircraft in the second mode where the output of the rate controller is proportional to the amplitude of the pilot stick signal.