Helicopter Active Vibration Control System Pilot Cueing
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Solution Overview
Problem
Helicopter pilots may not notice visual indicators when flight parameters such as rotor-induced vibration levels exceed operational constraints, leading to potential damage and restricted flight envelopes, as they can be distracted during flight.
Innovation Solution
The on-board active vibration control system is modified to temporarily detune or cease vibration suppression when excessive flight parameters are detected, causing increased airframe vibrations to serve as a tactile cue for the pilot to take corrective action, utilizing a power signal frequency adjustment based on rotor speed and input from the flight control computer or cruise guide indicator.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If visual indicators are used to alert pilots of excessive flight parameters, then pilots can be warned of dangerous conditions, but pilots may not notice the indicators when distracted during flight
Solution Approach 1:
The warning system is segmented into multiple independent channels: visual indicators on the display and tactile vibrations through the control stick. This segmentation ensures that if the pilot misses one channel due to distraction, the other channel can still convey the warning effectively.
Solution Approach 2:
The control stick serves as an intermediary device that translates excessive flight parameter conditions into tactile vibrations. This intermediary mechanism directly couples the warning system to the pilot's sense of touch through a familiar flight control interface, ensuring reliable perception regardless of visual attention.
2Reliability
If the active vibration control system continuously suppresses vibrations, then flight comfort and component protection are improved, but the system cannot provide tactile feedback to alert pilots of excessive conditions
Solution Approach 1:
The system employs periodic modulation of the vibration control actuator based on the magnitude of excessive flight parameters. When parameters exceed thresholds, the system introduces a periodic vibration component at a distinct frequency (e.g., 10-20 Hz) superimposed on the normal vibration suppression activity, creating a tactile warning signal.
Solution Approach 2:
The system continuously monitors flight parameters and provides real-time tactile feedback to the pilot through the control stick. The vibration characteristics (amplitude, frequency) are dynamically adjusted based on the degree of parameter exceedance, creating a closed-loop feedback system that informs the pilot of current operating conditions.
3Reliability
If the flight envelope is restricted to prevent component damage, then aircraft reliability is improved, but helicopter productivity and operational value are reduced
Solution Approach 1:
The pilot themselves monitors and responds to the tactile warnings generated by the system. Rather than requiring complex automated envelope protection systems that would restrict operations, the system empowers the pilot with intuitive tactile feedback, allowing them to self-regulate and maintain safe operations while maximizing productivity.
Solution Approach 2:
The system changes the vibration parameter characteristics (frequency, amplitude) of the control stick based on the degree of parameter exceedance. This dynamic parameter adjustment provides graduated warning levels that guide the pilot back into the safe flight envelope without requiring rigid operational restrictions.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
This approach provides a non-intrusive and intuitive method for pilots to recognize excessive operating conditions, ensuring flight safety and reducing the risk of component damage by converting the active vibration control system from an active to a standby state when oscillatory loads exceed specified thresholds.
Implementation Method 1
generating counter-vibrations in the airframe of the rotorcraft which have the frequency of the power signal while the measured flight parameter is less than the specified threshold
Implementation Method 2
The system detunes the cockpit active vibration control system based upon an input from the flight control computer, cruise guide indicator, or other input reading that results from an exceedance of the desired flight envelope
Data Source
AI summary
Systems and methods for cueing a helicopter pilot when a flight parameter (such as rotor-induced vibration level, airspeed, bank angle, icing accumulation, etc.) exceeds operational constraints. This is accomplished by reformulating the on-board cockpit active vibration control system to add a pilot cueing aid. When the measured flight parameter becomes excessive, the active vibration control system is temporarily detuned, which reduces the amount of vibration suppression it provides or turns off vibration suppression, causing an increase in airframe vibration levels to cue the pilot to take action (e.g., to fly within operating limits).