UAV Tether Management via Pivoting Angle Arm
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Solution Overview
Problem
Taut-tether methodologies for UAVs face challenges in maintaining a stable connection when the base station is subject to heaving, pitching, and rolling motions, especially at sea, leading to adverse dynamic stresses and potential tether separation.
Innovation Solution
A UAV tether management system comprising a spool with a slip ring, an angle arm that can pivot freely around its axis of rotation, and an angle arm encoder to measure and adjust the offset angle, allowing for a slack tether configuration that maintains minimal tension and reduces downward force on the UAV, even in dynamic sea conditions.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a taut-tether methodology is used to maintain tension on the tether, then the tether remains stable and connected to the UAV, but the dynamic stresses increase and the UAV may be pulled downward or the tether may separate during heaving, pitching, and rolling motions
Solution Approach 1:
The system transitions from a static taut-tether configuration to a dynamic slack-tether system where the tether length can change. The spool mechanism allows the tether to pay out or retract based on relative motion between the base station and UAV, accommodating heaving, pitching, and rolling motions without creating excessive tension or stress on the tether.
Solution Approach 2:
The system changes the key parameter of tether tension from high (taut) to low (slack). By maintaining minimal tension through the spool mechanism that can adjust tether length, the system reduces dynamic stresses while preserving connection reliability during platform motions.
2Reliability
If a taut-tether methodology is used to maintain tension on the tether, then the tether remains stable and connected to the UAV, but the downward force on the UAV increases
Solution Approach 1:
The spool mechanism enables dynamic adjustment of tether length to maintain a slack configuration, preventing the tether from acting as a rigid constraint that pulls the UAV downward during base station motions.
Solution Approach 2:
The counterweight mounted on the angle arm offsets the gravitational force on the angle arm itself, allowing the angle arm to freely pivot and follow the tether's angle without adding additional downward force on the UAV through the tether.
3Adaptability or versatility
If the angle arm is allowed to pivot freely around the axis of rotation, then the system can adapt to changing tether angles during platform motions, but the system complexity increases due to the need for encoders and control mechanisms
Solution Approach 1:
The angle arm assembly is designed to pivot freely under the influence of tether tension and counterweight balance, allowing it to self-adjust to changing tether angles without requiring active control. The angle arm encoder provides measurement capability, but the fundamental adaptation mechanism is passive and self-regulating.
Solution Approach 2:
The counterweight balances the gravitational moment on the angle arm, allowing it to pivot freely with minimal friction and without requiring active control torques. This passive balancing mechanism enables adaptability while keeping the control system simple.
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
The system enables the UAV to maintain position and reduce power consumption by keeping minimal tension in the tether, preventing separation and improving stability during heaving, pitching, and rolling motions, while allowing for autonomous tether management without the need for optics.
Implementation Method 1
The spool is configured to be rotatably mounted on a base station. The tether is wound on the spool and is configured to transfer power from the base station via the slip ring to the UAV while the UAV is in flight.
Implementation Method 2
The angle arm further comprises a counter weight mounted to a distal end of the angle arm such that a center of mass of the angle arm is aligned with the axis of rotation.
Data Source
AI summary
A UAV tether management system comprising: a tether-wound spool rotatably mounted on a base station, a free-pivoting angle arm, and an angle arm encoder, wherein the tether is configured to transfer power from the base station to the UAV while the UAV is in flight, and the angle arm comprises a tether guide mounted to a proximal end of the angle arm such that the tether passes through the tether guide as the tether pays out of, or is taken up by, the spool, wherein the angle arm further comprises a counter weight mounted to a distal end of the angle arm such that a center of mass of the angle arm is aligned with the spool's axis of rotation, and wherein the angle arm encoder is configured to measure an offset angle of the angle arm.