Conflict-free four-dimensional path planning for urban air mobility considering airspace occupancy

AIAA SCITECH 2022 Forum

2022

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As the use of multi-rotors is becoming common, understanding how the wake vortices develop and decay from a multi-rotor is important to reduce the effect of wake vortices on other multi-rotors and ensure their safety during operation by applying a wake separation minima. This paper proposes a method of flow simulation in ANSYS Fluent to study the decay of wake vortices from quadrotor propellers as the vortices evolve over distance and time. First, the near-field wake flow from the quadrotor propellers was simulated using Reynolds-Averaged Navier-Stokes (RANS) turbulence model. The velocity profile in the quadrotor frame of reference was then extracted to be applied for a flow simulation using Large Eddy Simulation (LES). The circulation strength as a function of distance could then be calculated, but it was limited by the length of the computational grid due to the wake flow being seen from the quadrotor frame of reference. To change into the stationary frame of reference, the interpolation data from the first stage LES was exported and modified by subtracting the freestream velocity from the velocity component in the freestream direction. The modified interpolation data was then used for the second stage LES, and the circulation strength in terms of time could be calculated from the resulting wake flow. Three cases of flow simulation are presented in this paper: first using 380-mm-diameter propellers based on the SUI Endurance quadrotor propellers with forward flight speed of 6 m/s, second using the 380-mm-diameter propellers with 12 m/s speed, and third using 240-mm-diameter propellers (similar to the propellers of DJI Phantom quadrotor) with 12 m/s speed. Findings regarding the decay of wake vortex from multi-rotor vehicles will help in determining the safe separation distance required to mitigate the hazards due to wake vortex encounters and ensure the safety of multi-rotor vehicles.

Section: Discussionmentioning

confidence: 99%

A Study on Circulation Strength Decay Over Time of Quadrotor Wake Using Large Eddy Simulation

Nathanael

Wang

AIAA SCITECH 2022 Forum

2022

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“…In the context of Singapore's strict air space regulations where the authorized drone flying zones are extremely scarce, we hope that this paper will be able to identify areas of low risk, and consequently open up more areas for safe drone operations in Singapore. The weather data analysis results can also be used to generate an environmental risk-map, which will contribute to the design of urban air route network [30] and safe UAV path optimization [31].…”

Section: Summariesmentioning

confidence: 99%

Environmental Data Analytics for Safe Drone Operations in Low-Altitude Urban Environments

Lee

Pang

AIAA AVIATION 2022 Forum

2022

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Drone operations in low-altitude urban airspace might be influenced by weather conditions such as wind and rainfall. Severe weather conditions may exceed the threshold of drone tolerability and cause crash accidents, posing risks to people and property. To investigate the influence of weather conditions on drone operation, this paper presents a data-driven method for analysis of weather data and to identify different levels of risk for safe drone operations. Obtained weather data is first collected across Singapore's 63 weather stations, and trend analysis are conducted to test if there are any significant trends in the yearly weather data. The risk standards in low-altitude urban environments are then classified based on the risk cost model. Similar levels of risk are clustered depending on the geographical location. Preliminary results show that the present weather data can be used to model our simulations as past historical weather data have no significant deviations. The results also concluded that low to high rainfall usually occurs at low wind speeds while high wind speeds tend to have low rainfall. The weather data analysis results can be used to generate an environmental risk-map for safe airspace planning and UAV path optimization.

“…The environment is discretized into regular grids using the "AirMatrix" concept [48]. The concept of "AirMatrix" is proven to be an outstanding tool in airspace management [49], [50], it has the flexibility to easily in cooperate various element like third party risk [51] [52] and swarm based path planning [53].…”

Section: Figure 6 Lakeside Area In Singaporementioning

confidence: 99%

Preliminary Study on Drone Navigation in Urban Environments using Visual Odometry and Partially Observable Monte Carlo Planning

Zhang

AIAA AVIATION 2022 Forum

2022

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