Tethered UAV Payload Damping Using Forward Flight Drag
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Solution Overview
Problem
Unmanned aerial vehicles (UAVs) face challenges in effectively damping oscillations of payloads coupled to a tethered winch system, which can lead to instability during payload delivery and retrieval operations.
Innovation Solution
The implementation of a control system that switches to forward flight mode to induce drag on the payload, reducing flight stabilization along certain dimensions to dissipate energy and dampen oscillations, and a payload coupling apparatus with a solid-state design that includes cams for secure attachment and release mechanisms to manage tether operations without moving parts.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the UAV uses traditional hover mode with flight stabilization for payload delivery, then the payload can be delivered to the target location, but oscillations of the payload cannot be effectively damped leading to instability
Solution Approach 1:
The patent applies dynamics by transitioning the UAV from a static hover mode to a dynamic forward flight mode during payload delivery. The control system commands the UAV to move forward at a controlled speed, creating aerodynamic drag on the payload that actively dampens oscillations. This dynamic approach replaces traditional passive stabilization systems with an active motion-based damping mechanism, improving payload stability without requiring complex mechanical stabilization components.
2Stability of the object's composition
If the UAV moves forward to create drag on the payload, then oscillations are damped, but the complexity of control system increases
Solution Approach 1:
The control system implements self-service by autonomously managing the entire payload delivery process without continuous human intervention. It automatically detects payload oscillations, determines the optimal forward speed to create appropriate drag, executes the forward flight maneuver, monitors the damping effect, and returns to hover mode when delivery is complete. This integrated autonomous control simplifies the overall system architecture by replacing complex mechanical damping mechanisms with a software-controlled aerodynamic damping approach.
3Ease of operation
If a traditional payload release mechanism is used, then the payload can be released, but the mechanism may re-engage with the UAV or external obstacles
Solution Approach 1:
The patent extracts the payload from the UAV system by using a tethered release mechanism that completely separates the payload from the aircraft after delivery. The payload is lowered on a tether to the target location, then the release mechanism disengages, leaving the payload independent from the UAV. This extraction approach eliminates the risk of re-engagement between the release mechanism and the UAV, as well as potential interference with external obstacles, since the payload and release mechanism are fully separated after the delivery operation.
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
This solution enhances the stability and reliability of payload delivery and retrieval by effectively damping oscillations and ensuring secure, automatic attachment and release, reducing the risk of re-engagement with the UAV or external obstacles.
Implementation Method 1
the UAV's control system may dampen the oscillations by causing the UAV to switch to a forward flight mode in which movement of the UAV results in drag on the payload, thereby damping the oscillations due to the drag
Implementation Method 2
the control system may cause the UAV to reduce an extent of flight stabilization along at least one dimension, thereby resulting in damping of the detected oscillations due to energy dissipation during movement of the UAV along the at least one dimension
Data Source
Figure 1A
Figure 1B~1C
Figure 1D
AI summary
Described herein are methods and systems to dampen oscillations of a payload coupled to a tether of a winch system arranged on an unmanned aerial vehicle (UAV). For example, the UAV's control system may dampen the oscillations by causing the UAV to switch to a forward flight mode in which movement of the UAV results in drag on the payload, thereby damping the oscillations. In another example, the control system may cause the UAV to reduce an extent flight stabilization along at least one dimension, thereby resulting in damping of the detected oscillations due to energy dissipation during movement of the UAV along the dimension. In this way, the control system could select and carry out one or more such techniques, and could do so during retraction and/or deployment of the tether.