UAV Heading Estimation via GNSS Speed Vector
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Solution Overview
Problem
Unmanned aerial vehicles (UAVs) face challenges in determining their head direction when a magnetometer is invalid or under strong magnetic interference, leading to difficulties in automatic returning and safety protection, especially as existing solutions like dual GNSS receivers increase weight and cost.
Innovation Solution
An automatic returning system that uses a low-cost GNSS receiver and specific flight actions to estimate the aircraft's heading, accelerating the UAV in the assumed head direction, obtaining speed values, and adjusting the heading angle to ensure safe return without additional hardware.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If dual GNSS receivers are loaded to determine heading under magnetic interference, then heading accuracy is improved, but weight and production costs increase
Solution Approach 1:
The patent uses a low-cost single GNSS receiver to copy the functionality of expensive dual GNSS receivers by implementing software-based dual-antenna RTK positioning algorithms. The system processes signals from one receiver as if from two receivers, achieving comparable heading accuracy without the additional hardware weight and cost.
Solution Approach 2:
The patent replaces the mechanical/hardware solution of dual GNSS receivers with a software-based processing system. By using signal processing algorithms and computational methods, the system achieves the same positioning and heading determination functionality without adding physical hardware components.
2Measurement precision
If higher precision sensors are used to estimate heading and location under magnetic field interference, then measurement precision is improved, but manufacturing costs increase
Solution Approach 1:
The patent changes the operational parameters of the low-cost GNSS receiver by implementing RTK (Real-Time Kinematic) positioning algorithms that process carrier-phase measurements. This parameter change in the signal processing approach enables high-precision positioning and heading estimation without requiring expensive high-precision hardware sensors.
Solution Approach 2:
The system copies the functionality of expensive high-precision sensors by implementing advanced algorithms in software that replicate the measurement and processing capabilities of costly hardware, achieving the same precision outcomes at lower manufacturing cost.
3Device complexity
If GNSS speed information is used to estimate location for multi-rotor aircraft, then location estimation is simplified, but heading determination accuracy deteriorates because multi-rotor aircraft can fly in any direction without a fixed forward direction
Solution Approach 1:
The patent transitions from using only speed information (one-dimensional approach) to utilizing dual-antenna phase difference measurements (adding a spatial dimension). By measuring the phase difference of GNSS signals between two antennas, the system can determine heading angle directly in any direction, solving the fundamental limitation of speed-based methods for multi-rotor aircraft.
Data Source
AI summary
The present invention relates to unmanned aerial vehicles. The method includes: when the magnetometer is invalid or encounters strong magnetic interference, assuming that a track angle is equivalent to the head direction, and accelerating the aircraft in a head direction; determining whether a speed obtained after the aircraft is accelerated reaches a preset value; if the speed reaches the preset value, obtaining the track angle of the aircraft according to the speed; obtaining a current location and a home point of the aircraft by using a positioning system that can provide global or local coordinates, to obtain a heading angle of the aircraft; determining whether a difference between the heading angle of the aircraft and the track angle of the aircraft is less than a fixed value.