Multi-UAV Load Control Using Variable-Length Suspension Cables
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Solution Overview
Problem
Existing control methods for hover-capable aircraft, such as vertical take-off and landing multicopters, cannot independently alter the attitude of a load being transported without affecting the attitude and altitude of the aircraft, leading to inaccuracies in delivery, especially on uneven terrain or in confined spaces.
Innovation Solution
A method using flexible elements connected to both the aircraft and the load, with length-altering devices like winches, allows for independent adjustment of the load's attitude and position without changing the aircraft's attitude or altitude, by varying the length of these elements.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If the attitude and position of the load are altered by changing the aircraft's attitude and altitude, then the load can be delivered to different locations, but the delivery precision deteriorates due to coupled movements and inaccuracies
Solution Approach 1:
The system segments the control functions by separating aircraft position control from load attitude control. The aircraft maintains a stable hovering position while the load's attitude is independently adjusted through flexible element length modification, decoupling the previously coupled movements and improving delivery precision
Solution Approach 2:
The flexible elements (cables, ropes, or chains) serve as intermediaries between the aircraft and the load. By altering the length of these flexible elements through winches or reeling devices, the system can adjust load attitude without requiring aircraft movement, thereby improving delivery precision while maintaining simple aircraft control
2Weight of moving object
If multiple UAVs are used to carry heavier loads, then the payload capacity increases, but the control complexity and coordination difficulty increase
Solution Approach 1:
The system merges the control functions of multiple UAVs under a centralized control unit that coordinates their movements. The UAVs fly in formation and maintain synchronized positions, allowing them to collectively carry heavier loads while the centralized control manages coordination to prevent complexity escalation
Solution Approach 2:
The flexible elements act as counterbalancing mechanisms that allow individual UAVs to make minor position adjustments without affecting the overall system stability. This distributes the control burden across multiple UAVs while maintaining coordinated operation for heavy payload transport
3Stability of the object's composition
If rigid connection between UAVs is used, then the structural stability improves, but the adaptability to different delivery scenarios deteriorates
Solution Approach 1:
The system transitions from rigid to dynamic connections using flexible elements with variable lengths. The flexible elements can be extended or retracted based on delivery requirements, allowing the system to adapt to different delivery scenarios while maintaining structural stability through controlled tension and synchronization
4Manufacturing precision
If the aircraft alters its attitude to change load orientation, then the load orientation changes, but the delivery position accuracy deteriorates due to position-attitude coupling
Solution Approach 1:
The control system segments orientation adjustment from position control. The aircraft maintains a fixed hovering position while the load's orientation is independently adjusted by modifying flexible element lengths, completely decoupling position and attitude control to achieve both high position accuracy and orientation precision
Solution Approach 2:
The flexible elements serve as intermediaries that transmit force and torque from the aircraft to the load without requiring aircraft attitude changes. By controlling the length and tension of these flexible elements, the system can precisely orient the load while the aircraft remains stationary, achieving both position and orientation precision
Data Source
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AI summary
A method is proposed for controlling a plurality of hover-capable aircraft (2; 2.1-2.4), preferably vertical take-off and landing multicopters having a plurality of spaced-apart, electrically driven rotors, during transportation of a load (1), which load (1) is carried jointly by all aircraft (2; 2.1-2.4) by means of at least one flexible element (3; 3.1-3.4) in each case, wherein an attitude and/or a position of the load (1) is altered by altering a length of at least one of the flexible elements (3; 3.1-3.4). The attitude and/or position of the load can thus be altered without the aircraft needing to alter their altitudes and/or attitudes.