Rotorcraft Laser Scanning via Magnetometer Frequency Estimation
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Solution Overview
Problem
Conventional rotorcrafts face challenges in achieving miniaturization and autonomy while performing laser scanning due to the limitations of commercially available gyroscopic sensors, which restrict further miniaturization and increase weight and complexity when additional sensors are added for autonomy.
Innovation Solution
A method and system that utilize a magnetometer to measure magnetic field data, estimate its frequency, and control a laser rangefinder for laser scanning, eliminating the need for additional sensors and thus minimizing weight and complexity, using either an extended Kalman filter or phase-locked loop for angular rate estimation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If additional sensors are added for autonomy and laser scanning, then measurement precision and autonomy are improved, but weight and device complexity increase
Solution Approach 1:
The magnetometer is repurposed from its traditional navigation function to also serve angular rate measurement for laser scanning control. By utilizing the magnetometer's ability to detect magnetic field variations during rotorcraft rotation, the system achieves dual functionality without adding dedicated sensors, thereby resolving the contradiction between measurement precision and device complexity
Solution Approach 2:
The existing magnetometer on the rotorcraft is made to serve itself by extracting angular rate information from its own magnetic field measurements during rotation. The sinusoidal signal generated during rotation is processed to estimate angular frequency, allowing the same sensor to provide both navigation and scanning control functions, eliminating the need for additional sensors
2Measurement precision
If additional sensors are added for autonomy and laser scanning, then measurement precision is improved, but weight increases
Solution Approach 1:
The magnetometer performs dual functions: traditional magnetic navigation and angular rate measurement for laser scanning. By extracting rotational frequency information from the sinusoidal magnetic field signal generated during rotorcraft rotation, the system eliminates the need for separate angular rate sensors, thereby preventing weight increase while maintaining measurement precision
Solution Approach 2:
The magnetic field acts as an intermediary carrier that encodes angular rate information during rotorcraft rotation. By measuring the frequency of the sinusoidal magnetic field signal, the system indirectly obtains angular rate data without requiring direct mechanical or inertial sensing, thus avoiding additional sensor weight
3Measurement precision
If gyroscopic sensors are used for angular rate measurement, then measurement precision is improved, but device complexity and weight increase
Solution Approach 1:
The patent replaces the mechanical gyroscopic system with a magnetic field-based measurement approach. Instead of using physical gyroscopes to detect angular rate, the system uses the magnetometer to capture magnetic field variations during rotation and estimates angular frequency through signal processing, thereby eliminating mechanical complexity while maintaining measurement capability
Solution Approach 2:
The system creates a virtual angular rate signal by processing the magnetic field measurements. The sinusoidal signal generated during rotation is analyzed to estimate angular frequency, producing a digital representation of angular rate without physical gyroscopic sensors, thus reducing device complexity while preserving measurement precision
4Device complexity
If the rotorcraft is miniaturized, then device complexity is reduced, but measurement precision of angular rate decreases due to gyroscopic saturation
Solution Approach 1:
The patent replaces the mechanical gyroscopic system with a magnetic field-based measurement approach that is not subject to saturation limitations. The magnetometer measures magnetic field variations during rotation, and the angular frequency is estimated through signal processing of the sinusoidal signal, allowing accurate measurement even in miniaturized rotorcraft where rotational speeds are higher
Solution Approach 2:
The system changes the measurement parameter from direct angular velocity (prone to saturation in small rotorcraft) to the frequency of magnetic field variations during rotation. This parameter transformation allows the system to accurately measure high rotational speeds in miniaturized platforms without encountering gyroscopic saturation limits
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
Enables efficient laser scanning with high angular rate estimation, allowing rotorcrafts to operate beyond gyroscopic saturation limits, achieving accurate localization and mapping without increasing the rotorcraft's weight or complexity, and facilitating miniaturization.
Implementation Method 1
a magnetometer configured to measure magnetic field; obtaining magnetic field measurement data from the magnetometer while the rotatable body frame is rotating during flight
Data Source
AI summary
There is provided a method of controlling laser scanning by a rotorcraft. The rotorcraft includes: a rotatable body frame configured to rotate during flight; a laser rangefinder mounted on the rotatable body frame and configured to perform laser scanning; and a magnetometer configured to measure magnetic field. The method includes: obtaining magnetic field measurement data from the magnetometer while the rotatable body frame is rotating during flight, the magnetic field measurement data including a sinusoidal signal; estimating a frequency of the sinusoidal signal; and controlling the laser rangefinder to perform laser scanning based on the estimated frequency of the sinusoidal signal. There is also provided a corresponding controller for controlling laser scanning by a rotorcraft, and a corresponding rotorcraft configured to perform laser scanning including the controller.