Rotor Blade Rate-Gyro Sensing for Accurate Rotor State Estimation
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Solution Overview
Problem
Existing methods for determining the state of a rotorcraft rotor, including longitudinal and lateral cyclic pitches and cone angle, are complex, prone to angle errors, and lack accuracy due to the use of multiple sensors and reliance on ambient light, making them unsuitable for commercial deployment.
Innovation Solution
A method utilizing direct measurements of angular velocity components from rate gyros, specifically MEMS type, secured to the rotor blades, which process these measurements to determine the rotor state without additional reference markers, providing robust and precise estimates of cyclic pitches and cone angle directly in the tip path plane.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If multiple sensors and reference markers are used to determine rotor state, then measurement coverage is improved, but device complexity and angle errors increase
Solution Approach 1:
The patent extracts and eliminates unnecessary reference markers and complex sensor systems from the measurement setup. By using only the rate gyro mounted on the blade and the known rotor rotation speed, the solution removes sources of complexity and angle errors while maintaining measurement capability through direct angular velocity measurement in the inertial frame.
Solution Approach 2:
The patent replaces complex mechanical sensor systems with a simplified approach using a rate gyro (inertial sensor) combined with computational processing. This substitution eliminates the need for mechanical reference markers and complex multi-sensor arrangements, reducing device complexity while maintaining or improving measurement precision.
2Measurement precision
If integration of sensor measurements over time is performed, then angle estimation is achieved, but unacceptable angle errors accumulate
Solution Approach 1:
The patent performs preliminary transformation of the measurement data into the inertial reference frame before any integration or processing. By expressing angular velocity directly in the inertial frame and using the known rotor speed to calculate azimuth, the system establishes accurate reference values beforehand, preventing error accumulation during subsequent processing.
Solution Approach 2:
The patent uses feedback from the known rotor rotation speed to continuously correct and update the azimuth calculation. This feedback mechanism ensures that the reference values remain accurate over time, preventing error accumulation and maintaining reliable angle estimation without requiring long-term integration of sensor measurements.
3Ease of manufacture
If ambient light-dependent methods are used for measurement, then implementation is simplified, but reliability and operational capability are reduced
Solution Approach 1:
The patent replaces optical measurement methods (which depend on ambient light) with inertial sensing using a rate gyro. This substitution eliminates dependence on ambient light conditions while maintaining implementation feasibility, as rate gyros are standard commercial components that provide reliable measurements in all lighting conditions.
4Measurement precision
If rate gyros are mounted directly on rotor blades, then direct angular velocity measurement is achieved, but measurement bias and uncertainty are eliminated
Solution Approach 1:
The patent segments the measurement system by mounting the rate gyro directly on the rotor blade, separating the measurement function from the control system. This segmentation allows direct measurement of blade angular velocity in the inertial frame, eliminating biases that would arise from indirect measurements or reference frame transformations.
Solution Approach 2:
The rate gyro mounted on the blade performs self-service by directly measuring its own angular velocity relative to the inertial frame. This self-measurement capability eliminates the need for external reference systems and prevents uncertainty introduced by reference marker alignment or sensor calibration errors.
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 eliminates bias and uncertainty, offers improved accuracy, and simplifies the measurement process, enabling more reliable and efficient monitoring of rotorcraft rotor states, reducing complexity and enhancing operational reliability.
Implementation Method 1
directly measuring the change over time of an angular velocity component of a blade about an articulation axis; a sensor arranged on this blade, this sensor comprising at least one rate gyro
Data Source
AI summary
A device for determining a state of a rotor of a rotorcraft. The rotorcraft comprises a fuselage and a main rotor provided with a hub rotating about a mast of the rotor and with a plurality of blades whose second ends describe a trajectory defining a tip path plane. The device includes a sensor for measuring an angular velocity of a blade about a pitch axis. The device thus makes it possible to determine a state of the rotor, comprising, for example, estimates of a longitudinal cyclic pitch and of a lateral cyclic pitch of the blade with respect to the tip path plane.