Helicopter Inertial Reference System Leveling via Motion Mode Identification
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Solution Overview
Problem
Helicopter inertial reference systems face challenges in accurately determining initial roll and pitch angles during motion, such as when rotors are on or when deployed from an aircraft carrier, leading to degraded accuracy in leveling and alignment processes.
Innovation Solution
A method involving a fast Fourier transform algorithm to determine the current operation mode of a helicopter, selecting the appropriate leveling algorithm based on sensor data analysis, and executing multiple leveling algorithms in parallel to ensure accurate roll and pitch angle estimation regardless of motion.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If the helicopter is in motion during leveling and alignment, then the system can be deployed more quickly (e.g., from aircraft carrier), but the accuracy of the estimated roll and pitch angle degrades
Solution Approach 1:
The system dynamically adapts the leveling algorithm based on detected motion characteristics. The processor executes a motion detection algorithm that analyzes accelerometer data to determine if the helicopter is in motion, then selects between a first leveling algorithm for motion conditions and a second leveling algorithm for stationary conditions, optimizing both speed and accuracy for the current operational state
Solution Approach 2:
The system changes the parameters of the leveling process by selecting different algorithms based on motion detection. When motion is detected, the system switches to a motion-appropriate algorithm that can process data more quickly despite the motion degradation, effectively changing the computational parameters to match the operational conditions
2Measurement precision
If different leveling algorithms are used for motion and stationary conditions, then accuracy is maintained, but the completion time is significantly increased
Solution Approach 1:
The system dynamically selects the appropriate leveling algorithm based on real-time motion detection rather than always using the most accurate but time-consuming algorithm. The motion detection algorithm continuously monitors accelerometer data, and when motion is detected, the system switches to a faster motion-appropriate algorithm, thereby reducing completion time while maintaining accuracy through adaptive selection
Solution Approach 2:
The system applies a motion detection algorithm that analyzes only the necessary portion of sensor data to determine motion state, then applies the appropriate leveling algorithm. This partial analysis approach (detecting motion rather than fully processing all navigation data) reduces the time investment before initiating the main leveling process
Data Source
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Figure 3A~3C
AI summary
A method to level an inertial reference system of a helicopter with reference to the local vertical frame is provided. The method includes powering up the helicopter; outputting sensor data from at least one gyroscope and at least one accelerometer to a mode-selecting processor; executing a fast Fourier transform algorithm on the sensor data at the mode-selecting processor; andselecting one of a plurality of operation modes of the helicopter as a current-operation mode based on the execution of the fast Fourier transformalgorithm.