Tethered Hook Position Control for Precise UAV Payload Pickup
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Solution Overview
Problem
Unmanned aerial vehicles (UAVs) face challenges in accurately and efficiently picking up and dropping off payloads without human intervention, particularly due to oscillations and delays in controlling the payload coupling apparatus via a tether, which affects precision and stability during operations.
Innovation Solution
The implementation of a winch system with a tether and a payload coupling apparatus, combined with a repositioning device such as wheels, fins, or a robotic arm, allows for precise control over the horizontal and vertical positioning of the payload coupling apparatus, enabling direct mechanical coupling to the payload with reduced oscillations and improved accuracy.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If a tether is used to control the payload coupling apparatus, then the apparatus can be deployed and retracted, but oscillations and delays occur during positioning
Solution Approach 1:
A repositioning device acts as an intermediary between the tether and the payload coupling apparatus. The device includes a platform that receives the tether and a repositioning mechanism that directly adjusts the horizontal position of the payload coupling apparatus, eliminating oscillations caused by tether manipulation alone.
Solution Approach 2:
The positioning system is segmented into two independent functions: vertical positioning controlled by the tether/winch system and horizontal positioning controlled by the repositioning device. This segmentation allows each subsystem to optimize its function without interfering with the other, improving overall positioning accuracy.
2Speed
If the UAV repositions itself to control the payload coupling apparatus, then vertical positioning is achieved, but horizontal precision is limited by tether length and oscillations
Solution Approach 1:
The repositioning device serves as a mediator that directly controls horizontal positioning of the payload coupling apparatus independent of UAV movement. This eliminates the indirect control chain where UAV position → tether angle → payload position, replacing it with direct control for higher precision.
3Measurement precision
If a repositioning device is added to control horizontal position, then positioning precision improves, but system complexity increases
Solution Approach 1:
The repositioning device is designed to perform multiple functions: horizontal positioning of the payload coupling apparatus, stabilization during payload engagement, and coordination with the winch system. This multi-functionality justifies the added complexity by consolidating several control tasks into a single integrated device.
Data Source
Figure 1A
Figure 1B~1C
Figure 1D
AI summary
An example system includes an aerial vehicle, a sensor, and a winch system. The winch system includes a tether disposed on a spool, a motor operable to apply a torque to the tether, and a payload coupling apparatus coupled to the tether and configured to mechanically couple to a payload. The system also includes a repositioning apparatus configured to reposition the payload coupling apparatus in at least a horizontal direction. A control system is configured to control the aerial vehicle to deploy the payload coupling apparatus by unwinding the tether from the spool; receive, while the aerial vehicle hovers above the payload and from the sensor, data indicative of a position of the payload coupling apparatus in relation to the payload; and reposition, using the repositioning apparatus and based on the data, the payload coupling apparatus in the horizontal direction to mechanically couple to the payload.