Rotorcraft Torque Calibration via Aerodynamic Reference
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Solution Overview
Problem
Traditional methods for calibrating torque measurement systems in rotorcraft require a zero-torque condition, which is time-consuming, costly, and poses safety hazards, especially when measuring tail rotor torque.
Innovation Solution
A system and method for calibrating torque measurements using a reference operating condition with a known, non-zero torque, employing a torque model that accounts for operational and atmospheric conditions to estimate torque precisely.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If traditional zero-torque calibration method is used, then measurement precision is improved, but maintenance time and cost increase significantly
Solution Approach 1:
The patent changes the calibration parameter from zero-torque condition to a known non-zero torque condition. By using a reference operating condition where the torque is known (such as when rotor blades are at a specific pitch angle), the system can perform calibration without requiring complete disassembly and zero-load conditions, thus reducing maintenance time while maintaining measurement precision.
Solution Approach 2:
The patent performs preliminary estimation of the reference torque using aerodynamic models and operational parameters before actual calibration. This preliminary action allows the system to prepare calibration data in advance during normal operation, eliminating the need for time-consuming zero-torque setup procedures.
2Measurement precision
If traditional zero-torque calibration method is used, then measurement precision is improved, but device complexity and maintenance cost increase
Solution Approach 1:
The patent simplifies the calibration procedure by changing from zero-torque conditions to known non-zero torque conditions. This parameter change eliminates the need for removing rotor blades and creating artificial zero-load conditions, thereby reducing device complexity and maintenance cost while preserving measurement precision through aerodynamic modeling.
Solution Approach 2:
The patent replaces the mechanical approach of physically removing components to achieve zero torque with an aerodynamic modeling approach. By using computational models to estimate reference torque based on operational parameters, the system substitutes complex mechanical disassembly procedures with simpler computational methods.
3Measurement precision
If traditional zero-torque calibration method is used, then measurement precision is improved, but safety hazards increase
Solution Approach 1:
The patent changes the calibration condition parameter from zero-torque (requiring rotor removal) to known non-zero torque (normal operation). This parameter change eliminates safety hazards associated with operating aircraft without essential components like tail rotors, while maintaining measurement precision through aerodynamic reference models.
Solution Approach 2:
The patent converts the previously harmful condition of operating without full rotor assembly into a beneficial calibration opportunity. By using normal operational conditions with known torque characteristics as the calibration reference, the system turns what was previously a safety risk into a safe and efficient calibration method.
Data Source
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AI summary
A torque measurement system determines torque on a shaft (301) by monitoring angular deflection of the shaft (301) under load using phase shift measurements (314, 315). Calibration of the system uses a defined offset that is determined using a reference operating condition. The offset calibration value is determined for a rotorcraft using the following steps: defining a reference operational condition in which the shaft is rotating, estimating the torque at the reference condition based on aerodynamic knowledge of the rotors coupled to the shaft, operating the shaft at the reference operational condition, capturing sensor data to determine the phase difference at the operational condition, and associating the phase difference and an estimated torque as a calibration value to enable calculation of torque in the torque measurement system.