Tethered UAV Altitude Control for Moving Base Stability
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Solution Overview
Problem
Existing unmanned aerial vehicle (UAV) control systems fail to maintain a stable relative altitude with respect to a mobile object, such as a boat or vehicle, leading to excessive load on the UAV and inaccurate image capture, especially when the mobile object moves due to water waves or terrain variations.
Innovation Solution
A control system comprising a base device mounted on a mobile object, an unmanned aerial vehicle connected via a power supply cable, and a control device that adjusts the UAV's altitude based on sensors detecting cable tension and angle, GPS receivers, inertial measurement units, and barometric altitude sensors to maintain a target relative altitude, ensuring stable operation and accurate positioning.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If the UAV maintains a fixed altitude, then the battery capacity can be smaller, but the relative altitude stability with respect to the mobile object deteriorates when the mobile object moves due to water waves or terrain variations
Solution Approach 1:
The patent implements dynamic altitude adjustment by continuously monitoring the mobile object's position via GPS and cable state via sensors, then adjusting the UAV's altitude in real-time to maintain a stable relative position. This resolves the contradiction by making the altitude adaptive rather than fixed, allowing the system to respond to mobile object movements while managing battery consumption efficiently.
Solution Approach 2:
The system employs feedback control through sensors that detect cable tension and angle, combined with GPS positioning data. The control device processes this feedback information and adjusts the UAV's altitude accordingly, ensuring relative altitude stability while optimizing battery usage based on actual operational conditions.
2Measurement precision
If the UAV follows the mobile object's movement, then the image capture accuracy improves, but the load on the UAV from the cable increases
Solution Approach 1:
The system dynamically adjusts the UAV's altitude based on real-time detection of cable tension and angle, combined with GPS position data. When the mobile object moves, the system calculates the optimal altitude that maintains image capture accuracy while minimizing cable load through controlled following movement rather than passive dragging.
Solution Approach 2:
Sensors monitoring cable tension and angle provide feedback to the control device, which adjusts the UAV's position to balance image capture requirements with cable load management. The system uses this feedback to determine when to follow the mobile object's movement and when to maintain position.
3Adaptability or versatility
If the cable is allowed to deflect freely, then the UAV has more freedom of movement, but the altitude calculation accuracy deteriorates
Solution Approach 1:
The system uses sensors to detect cable angle and tension, providing feedback that enables the control device to calculate corrected altitude values. This feedback mechanism allows the UAV to maintain movement freedom while compensating for cable deflection effects on altitude measurements, thus preserving calculation accuracy.
Solution Approach 2:
The cable itself serves as an intermediary element whose state (angle and tension) is monitored to infer altitude information. By measuring cable deflection and using this data in altitude calculations, the system converts the potentially harmful effect of cable flexibility into useful measurement information.
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 optimizes the UAV's altitude in accordance with the mobile object's movement, reducing cable deflection and improving altitude calculation accuracy, enabling stable and precise control of the UAV's relative altitude, even in dynamic environments.
Implementation Method 1
an inertial measurement unit mounted on the mobile object. The control device may calculate the altitude of the mobile object based on a signal obtained by the first GPS receiver and an output of the inertial measurement unit
Implementation Method 2
a first barometric altitude sensor mounted on the mobile object and a second barometric altitude sensor mounted on the unmanned aerial vehicle. The control device may use an altitude of the mobile object calculated from an output of the first barometric altitude sensor and an altitude of the unmanned aerial vehicle calculated from an output of the second barometric altitude sensor
Data Source
AI summary
A control system includes a base device to be mounted on a mobile object, an aerial vehicle, a cable including a power supply cable for supplying electric power from the mobile object to the aerial vehicle and connecting the base device with the aerial vehicle, and a control device that controls flight of the aerial vehicle. The control device controls the aerial vehicle so that a relative altitude of the aerial vehicle with respect to the mobile object matches a target relative altitude. This control system optimizes an altitude of the aerial vehicle in accordance with the mobile object.