Tether-Based UAV Altitude Measurement Under Wind Displacement
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Existing unmanned aerial vehicles (UAVs) lack an efficient method to determine their altitude based on tether deployment, especially in environments with wind, which affects the accuracy of altitude measurements.
Innovation Solution
The UAV system includes a tether configured to allow a tethered component, such as a payload coupling apparatus and/or payload, to be retracted towards and/or lowered from the aerial vehicle. Sensors measure the tension and length of the tether to determine the ground contact and lift-off times, enabling the calculation of a tether-based altitude. This system accounts for wind effects by modeling the tether as a hypotenuse or parabola.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If tether length is used to measure altitude without accounting for wind effects, then the measurement method is simple, but the measurement precision deteriorates due to wind-induced horizontal and vertical displacements
Solution Approach 1:
The patent applies parameter changes by modeling the tether geometry differently based on wind conditions. When wind is present, the system transitions from assuming a vertical tether to modeling it as a hypotenuse or parabola, adjusting the geometric parameters to account for horizontal displacement. This allows accurate altitude calculation by changing the mathematical model parameters rather than adding physical sensors.
Solution Approach 2:
The patent replaces mechanical altitude measurement sensors with a computational approach. Instead of using additional mechanical sensors to directly measure altitude, the system uses tension sensor data combined with mathematical modeling (hyperbolic or parabolic functions) to calculate altitude, substituting physical measurement with computational analysis.
2Reliability
If the tether is modeled as a vertical line, then the calculation is simple, but the reliability deteriorates in windy conditions where horizontal displacement occurs
Solution Approach 1:
The patent applies dynamics by making the tether model adaptive rather than static. The system dynamically selects between vertical line, hypotenuse, and parabolic models based on wind conditions and observed tether displacement. This dynamic adaptation ensures the model remains accurate across varying operational conditions without requiring complex hardware changes.
Solution Approach 2:
The patent changes the geometric parameters of the tether model based on environmental conditions. In calm conditions, the tether is modeled as a vertical line with simple height parameters. In windy conditions, the model transitions to a hypotenuse or parabola with additional parameters for horizontal displacement and curvature, adjusting the mathematical representation to match physical reality.
3Measurement precision
If additional sensors are added to measure wind effects and tether geometry, then the measurement precision improves, but the device complexity increases
Solution Approach 1:
The patent replaces mechanical measurement sensors with computational analysis. Instead of adding wind sensors and geometry sensors to physically measure wind speed and tether angle, the system uses existing tension sensor data combined with mathematical modeling to infer these parameters, substituting physical sensing with computational derivation.
Solution Approach 2:
The patent introduces mathematical models (hyperbolic and parabolic functions) as intermediaries between the physical tether system and the altitude measurement. These mathematical relationships act as mediators that translate tension sensor readings into accurate altitude measurements without requiring direct physical measurement of wind effects or tether geometry.
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 provides accurate tether-based altitude measurements, even in windy conditions, by accounting for horizontal and vertical displacements caused by wind, thereby enhancing the precision and reliability of UAV operations.
Implementation Method 1
a tether configured to allow a tethered component, such as a payload coupling apparatus and/or a payload, to be retracted towards and/or lowered from the aerial vehicle
Implementation Method 2
Sensors measure the tension and length of the tether to determine the ground contact and lift-off times
Data Source
AI summary
A method includes obtaining sensor data indicating a tension experienced by a tether while a payload coupling apparatus connected to the tether is lowered from an aerial vehicle using the tether. The method also includes determining, based on the sensor data, a ground contact time at which the payload coupling apparatus or a payload coupled thereto made initial contact with a ground surface. The method additionally includes determining a length of the tether released from the aerial vehicle at the ground contact time. The method further includes determining a tether-based altitude of the aerial vehicle based on the length of the tether released from the aerial vehicle at the ground contact time. The method yet further includes causing the aerial vehicle to perform an operation based on the tether-based altitude.