Tethered UAV Navigation on Moving Platforms Without GNSS
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Solution Overview
Problem
Tethered unmanned aerial vehicles (UAVs) face challenges in mobility and precision navigation when operating from mobile platforms, as standard GNSS solutions are insufficient for maintaining precise position and altitude, especially in GPS-denied environments and when the ground portion is moving.
Innovation Solution
An optically guided precision UAS navigation system, an automatic Launch and Recovery System (LARS), and a tether break-away system are employed to enable precise launch, station-keeping, and landing of tethered UAVs relative to moving vehicles or vessels, using sensors and digital processing to adjust propeller control and tether management for accurate positioning and tension management.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Duration of action of moving object
If a tether is used to provide power and data to the UAV, then flight time is extended and payload capacity is increased, but the UAV's mobility and flight characteristics are affected
Solution Approach 1:
The system dynamically adjusts the tether length and tension based on real-time conditions. The spool mechanism allows the tether length to change as the UAV moves, and the tension control system actively manages the tether's restraint on the UAV, enabling both extended flight time and improved mobility.
2Adaptability or versatility
If the ground portion of the system is made mobile to increase versatility, then deployment flexibility is improved, but tether management complexity and tension control difficulty increase
Solution Approach 1:
The system uses sensors to continuously monitor tether tension, length, and the relative position between the ground portion and UAV. This feedback is processed by a control system that adjusts spool motor commands and propulsion commands to maintain optimal tether management, even when the ground portion is mobile.
Solution Approach 2:
The patent replaces traditional mechanical tether management with an optically-guided precision navigation system. Instead of relying on mechanical tension-only control, the system uses optical sensors and computer vision to precisely track the UAV's position and control its movement relative to the mobile ground portion.
3Device complexity
If standard GNSS solutions are used for navigation, then the system is simpler to implement, but precision positioning is insufficient especially in GPS-denied environments
Solution Approach 1:
The patent introduces an optical guidance system as an intermediary between the UAV and the ground portion. Instead of relying directly on GNSS signals, the system uses optical markers and computer vision algorithms to establish a relative positioning framework that works independently of GPS, achieving centimeter-level precision.
4Length of moving object
If the tether length is increased to expand operating range, then the UAV can operate farther from the ground portion, but tether mass increases and tension control becomes more difficult
Solution Approach 1:
The system dynamically manages tether length and tension through a controlled spool mechanism. Rather than using a fixed long tether, the spool actively pays out and reels in the tether based on real-time positioning and tension feedback, allowing the UAV to operate at extended ranges while maintaining manageable tension levels through active control.
Data Source
AI summary
Systems and methods including: a UAV comprising: a sensor configured to measure sensor data and a UAV propeller; a mobile platform; a tether attached to the UAV and to the mobile platform; and a digital processing device comprising: at least one processor, an operating system configured to perform executable instructions, a memory, and a computer program including instructions executable by the digital processing device to create a tethered UAV application comprising: a transmission module receiving the sensor data from the sensor at a selected rate; a locational module estimating a relative three-dimensional position of the UAV to the mobile platform, based on the sensor data; and a navigation module directing the UAV propeller and the mobile platform, based on the relative three-dimensional position, to adjust the relative three-dimensional position within a set value.