Optical Tether Angle Measurement for Slack UAV Winch Control
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Solution Overview
Problem
Conventional tethered UAV systems face challenges in accurately measuring tether departure angles, particularly in hanging or slack tether configurations, leading to measurement errors and reduced performance in tether management systems.
Innovation Solution
An optical system using 2D LIDAR technology with novel filtering and signal processing to measure the dynamic distance to the tether, calculating the tether departure angle by forming a triangle with known geometric parameters, and employing Cartesian and morphological filtering to eliminate noise and false returns.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If conventional tether management systems are used with slack tether configurations, then the system complexity is reduced and ease of operation is improved, but measurement precision of tether departure angle deteriorates
Solution Approach 1:
The patent replaces mechanical/optical measurement devices with a magnetic field-based sensor system. Instead of using complex optical apparatus to measure tether departure angle, the invention uses a magnetometer to detect the magnetic field signature of the tether, which indirectly provides departure angle information through signal processing. This substitution of measurement methodology reduces device complexity while maintaining measurement capability.
Solution Approach 2:
The patent introduces a magnetic field as an intermediary between the tether and the measurement system. Rather than directly measuring the tether's physical position or angle, the system measures the magnetic field disturbances caused by the tether and uses signal processing to derive departure angle information. This intermediary approach allows for simpler sensing hardware while achieving the measurement objective.
2Measurement precision
If optical measurement devices are used to measure dynamic distance to tether, then measurement precision is improved, but device complexity and cost increase
Solution Approach 1:
The patent substitutes optical measurement devices with magnetic field sensors (magnetometers). Instead of using LIDAR or other optical systems to measure dynamic distance to the tether, the invention uses magnetic field measurements combined with signal processing to derive position and distance information. This replacement significantly reduces device complexity and cost while maintaining measurement precision through sophisticated algorithms.
Solution Approach 2:
The patent creates a virtual model or representation of the tether's position and orientation by processing magnetic field measurements. Rather than directly measuring physical quantities with complex devices, the system constructs a digital model of the tether configuration based on magnetic field signatures, enabling accurate measurement inference from simpler sensor data.
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
Accurately measures tether departure angles in real-time, improving the performance of slack tether management systems by reducing measurement errors and enhancing control precision.
Implementation Method 1
optical measurement device attached to the support structure and configured for optically measuring a dynamic distance, a, along an optical path from the optical measurement device to the tether
Implementation Method 2
optically measuring a dynamic distance, a, along an optical path from the optical measurement device to the tether
Data Source
AI summary
The present invention involves systems and methods for tether length management between an uncrewed aerial vehicle (UAV), e.g., a drone, and a surface vehicle (SV), dynamically moving ground vehicle or an uncrewed SV (USV) base station. The tether departure angle control methodology of the present invention utilizes an optical method of measuring tether departure angle, which in combination with relative locations of the SV and UAV allows for a dynamic hanging tether management.