Tethered UAV Angle Sensing for GPS-Denied Flight Stability

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Solution Overview

Problem

Unmanned aerial vehicles (UAVs) are vulnerable to electromagnetic noise and lack of GPS signals, which can cause navigation failures and uncontrollable flight, especially in strong winds, limiting their operational independence.

Innovation Solution

A tethered automatic UAV system with an angle-sensor on the UAV and a preload assembly at the ground station, allowing the UAV to determine its angular position relative to the ground station independently of flight attitude and GPS, using a flexible tether that adjusts load and length to maintain stability and communication integrity.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Measurement precision

If GPS-based navigation is used for UAV flight control, then navigation accuracy is improved under normal conditions, but the system becomes vulnerable to electromagnetic noise and signal jamming causing navigation failure

Engineering Contradiction:
Improvenavigation accuracyVSAvoidnavigation reliability
Core Design Contradiction:
Measurement precisionVSReliability

Solution Approach 1:

The patent introduces a tether as an intermediary physical connection between the ground station and UAV. This mechanical tether serves as a backup navigation reference when electromagnetic-based GPS fails, allowing the system to switch to tether-based angular position measurement for reliable navigation under adverse conditions

Inventive Principle:
Principle #24Intermediary (Mediator)

Solution Approach 2:

The system changes the measurement parameter from GPS coordinates to angular position relative to the ground station via the tether. By measuring the angle of incidence between the tether and vertical direction, the system obtains position information that is independent of electromagnetic signals, thus resolving the contradiction between GPS accuracy and reliability

Inventive Principle:
Principle #35Parameter changes

2Adaptability or versatility

If the UAV operates without a tether in strong winds, then flight freedom is improved, but the risk of loss increases due to uncontrollable flight

Engineering Contradiction:
Improveflight freedomVSAvoidflight safety
Core Design Contradiction:
Adaptability or versatilityVSReliability

Solution Approach 1:

The tether system is designed to be dynamically adjustable, allowing the UAV to operate with varying degrees of freedom. The tether can be extended or retracted based on wind conditions and mission requirements, providing a balance between flight freedom and safety control

Inventive Principle:
Principle #15Dynamics

Solution Approach 2:

The tether acts as a pre-established safety mechanism that prevents complete loss of the UAV in adverse conditions. By having this physical backup connection in place before emergencies occur, the system cushions against the worst-case scenario of UAV loss while still allowing free flight during normal conditions

Inventive Principle:
Principle #11Beforehand cushioning (Prior cushioning)

3Adaptability or versatility

If an angle-sensor is added to the UAV to determine angular position, then navigation independence from GPS is improved, but the device complexity increases

Engineering Contradiction:
Improvenavigation independenceVSAvoidsensor system complexity
Core Design Contradiction:
Adaptability or versatilityVSDevice complexity

Solution Approach 1:

The patent extracts the navigation function from the complex GPS system and implements it through a simpler angular position measurement. By using an angle-sensor to measure only the angle of incidence relative to the vertical, the system achieves GPS-independent navigation with minimal additional complexity

Inventive Principle:
Principle #2Taking out (Extraction)

Solution Approach 2:

The angle-sensor on the UAV works in conjunction with the ground station to provide self-contained navigation capability. The system uses the physical tether and angular measurement to independently determine position without relying on external GPS infrastructure, achieving navigation independence through self-service

Inventive Principle:
Principle #25Self-service

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 UAVs to operate safely and reliably in adverse environments without GPS or clear communication, reducing the risk of loss due to electromagnetic interference and strong winds by maintaining tethered stability and secure control signals.

Implementation Method 1

determining an angle of incidence between the tether and gravity

Methodology Applied
Scientific EffectGravity: Gravitation

Implementation Method 2

the ground station is configured to preload the tether

Methodology Applied
Scientific EffectTension: Tension

Data Source

PatentEP4110694B1Tethered unmanned aerial vehicle system
Publication Date: 2025.01.15 ARROWTEC GMBH
  • EP4110694B1 patent drawingFigure 1
  • EP4110694B1 patent drawingFigure 2
  • EP4110694B1 patent drawingFigure 3

AI summary

The invention relates to a tethered unmanned aerial vehicle system (1) comprising at least the components: - an unmanned aerial vehicle (100), wherein the unmanned aerial vehicle (100) is a multi-copter, - a ground station (200), - a flexible tether (300) that is connectable or that is connected to the unmanned aerial vehicle (100) and to the ground station (200), such that the unmanned aerial vehicle (100) is tethered to the ground station (200), wherein the unmanned aerial vehicle (100) comprises an angle-sensor (104) configured and arranged to determine an angle of incidence (400) between the tether (300) and gravity (G), such as to determine from the detected angle of incidence (400) at least an angular position of the unmanned aerial vehicle (100) with respect to the ground station (200).