Rotary Wing Blade Tracking Using Wireless MEMS Sensors
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Solution Overview
Problem
Conventional methods for measuring blade track in rotary wing aircraft face challenges due to low contrast differences between light-colored blades and the background sky, leading to unreliable timing triggers and limited detection, especially at increased rotor speeds with reduced blade chord width, resulting in incomplete blade track data.
Innovation Solution
A blade tracking system comprising wireless blade sensors mounted on the aircraft blades and a reference sensor driven by the rotor hub, which transmit data to a processor for determining lead-lag, flap, and pitch motions, using MEMS-based sensors for accurate data processing and fusion across nine degrees of freedom.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If optical camera equipment is used to detect blade track, then blade track measurement is possible, but detection reliability deteriorates due to low contrast differences between light-colored blades and background sky
Solution Approach 1:
A reflective tape or marker is placed on the blade as an intermediary element. This intermediary has high reflectivity or contrast properties that enhance detection by the optical camera, solving the problem of low contrast between light-colored blades and sky without modifying the blade structure itself
Solution Approach 2:
The blade surface is modified with high-contrast markings, reflective materials, or color-coded sections that create detectable optical signatures. This allows the optical camera to reliably distinguish the blade from the background sky regardless of the blade's base color
2Speed
If rotor speed is increased with reduced blade chord width, then aircraft performance is improved, but detection capability deteriorates due to reduced blade visibility
Solution Approach 1:
High-contrast markings and reflective elements are applied to the blade surface to maintain detectability despite reduced chord width. These optical enhancements ensure the blade remains visible to the camera system even at higher rotation speeds where the blade occupies less visual space
Solution Approach 2:
The detection system uses periodic sampling synchronized with the rotor rotation cycle. This allows the system to accumulate multiple frames and detect the blade's periodic passage, compensating for the reduced visibility at high speeds through temporal integration
3Device complexity
If optical camera measures blade track at one azimuthal location, then measurement setup is simplified, but data completeness deteriorates due to limited measurement coverage
Solution Approach 1:
The measurement system is divided into multiple optical cameras positioned at different azimuthal locations around the rotor hub. Each camera captures blade track data from its specific viewpoint, and the processor integrates these segmented measurements to reconstruct complete three-dimensional blade motion trajectories
Solution Approach 2:
The system transitions from two-dimensional measurement at a single location to three-dimensional spatial measurement by adding cameras at multiple azimuthal positions. This dimensional expansion allows comprehensive capture of blade motion in all spatial directions
Data Source
AI summary
A blade tracking system for a rotary wing aircraft includes a blade sensor mounted on a blade of the rotary wing aircraft, the blade sensor wirelessly transmitting blade data; a reference sensor mounted to the rotary wing aircraft, the blade driven by the rotor hub, the reference sensor transmitting reference data; and a processor receiving the blade data and the reference data, the processor determining at least one of lead-lag, flap and pitch of the blade in response to the blade data and the reference data.