Tethered UAV Control for Precise Flight From Moving Platforms
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Solution Overview
Problem
Tethered unmanned aerial vehicles (UAVs) face challenges in mobility and precision navigation when operating from mobile platforms, such as boats, due to the limitations of standard GNSS solutions and RF transmitters in providing the necessary precision and stability.
Innovation Solution
The implementation of an optically guided precision UAS navigation system, an automatic Launch and Recovery System (LARS), and a tether break-away system, which enable precise navigation and control of UAVs relative to moving vehicles or vessels, allowing for centimeter-level accuracy and flexible mobility.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If standard GNSS solutions and RF transmitters are used for navigation, then the system is simple to implement, but the precision and stability are insufficient for mobile platform operations
Solution Approach 1:
The patent introduces an optical guidance system as an intermediary between the UAV and mobile platform. This system uses visual markers and computer vision algorithms to provide precise relative position information, bridging the gap between simple GNSS/RF systems and the need for centimeter-level accuracy during takeoff, landing, and station-keeping operations from moving platforms
2Duration of action of moving object
If a tether is deployed to provide power and data, then flight time and payload capacity are improved, but the tether creates variable mass and tension that affect flight characteristics
Solution Approach 1:
The patent implements a feedback control system that continuously monitors tether tension, length, and UAV position. The ground station processes this data and sends control commands to adjust motor thrust and tether payout rate, compensating for the variable mass and tension effects in real-time to maintain stable flight characteristics
Solution Approach 2:
The system dynamically adjusts operational parameters based on flight conditions. The tether payout rate, motor thrust, and control surface deflections are continuously modified in response to changing flight phase, wind conditions, and tether tension to optimize performance and ease of operation throughout the mission
3Adaptability or versatility
If the ground portion is moving (e.g., on a boat), then mobility is improved, but the precision required for tether management becomes significantly more difficult to achieve
Solution Approach 1:
The optical guidance system serves as a mediator that works independently of the mobile platform's motion. Visual markers mounted on the platform provide a stable reference frame that the UAV can track using computer vision, enabling precise relative position measurement even when the absolute position of the platform is changing due to waves or movement
Solution Approach 2:
The system compensates for the mobile platform's motion by using the optical guidance system to measure and counteract relative position changes. The feedback control adjusts UAV position in real-time to maintain the desired offset from the moving platform, effectively counterweighting the disturbance caused by platform motion
Data Source
AI summary
Disclosed herein are system and method for controlling an unmanned aerial vehicle (UAV) tethered from a mobile platform, the UAV system comprising: a UAV comprising one or more sensors, and one or more propellers; a tether attached to the UAV and to the mobile platform; a digital processing device comprising an operating system configured to perform executable instructions and a memory; and a computer program including instructions executable by the digital processing device to automatically control the UAV relative to the mobile platform comprising: a software module identifying the mobile platform; a software module estimating a real-time state of the mobile platform; and a software module automatically controlling three-dimensional real-time motion of the UAV based on the real-time state estimation of the mobile platform and data collected from the one or more sensors, such that the UAV is maintained at a predetermined position relative to the mobile platform.