Towards Autonomous MAV Soaring in Cities: CFD Simulation, EFD Measurement and Flight Trials

Abstract

MAVs are increasingly being used in complex terrains, such as cities, despite challenges from the highly turbulent flow fields. We investigate the flow around a nominally cuboid building of height 40m both computationally and experimentally in a 1/100th scale windtunnel test. A relatively new computational technique, Improved Delayed Detached Eddy Simulation (IDDES), was used for computing the time-varying flow around the building and surrounding domain. The atmospheric boundary layer velocity and turbulent intensity profiles were replicated at the inlet boundary of the computational domain and wind tunnel. The spatial flow field from the CFD was investigated for locating suitable areas of lift, in order to see if soaring flight would be feasible. Good agreement was found with the wind-tunnel results. Flight trials of a small flying wing aircraft were conducted from the roof demonstrating the possibility of keeping aloft with no conventional power system. Soaring was achieved under piloted control and autonomously. The CFD results proved useful in locating the best lift areas and provided insights into path planning.

Foraging in an unsteady world: bumblebee flight performance in field-realistic turbulence

“…Exploring such strategies is of particular interest given recent advances in biologically inspired flying robots [39]. While there is growing demand and interest in small, autonomous flying robots for use in urban, agricultural and natural environments, navigating such complex physical environments remains a significant challenge for MAVs [40,41].…”

Exploring tandem wing UAS designs for operation in turbulent urban environments

“…This can be particularly useful for on-board payloads which can be blurred due to rotational motion. Furthermore, the implementation of advanced pressure sensors 14–17 on tandem wing designs has the potential to enhance the time advantage by allowing the placement of the roll control surfaces (ailerons) further aft of the probe sensors and enables a number of control architectures to be utilised.…”

“…13 Active turbulence mitigation techniques have shown improved results when sensors with ability to detect the oncoming gusts are used. 14,15 Phase-advanced multi-hole pressure-based sensors which are able to react to the turbulence ahead of the leading edge have been developed, 16 and these have been shown to increase the stability of SUASs in turbulence. 17 This paper explores passive and active methods of aiding the stability of SUASs through experimental wind tunnel testing of a tandem wing airframe, in conjunction with the phase-advanced multi-hole pressure probes, to further enhance the attitude control performance in high levels of turbulence.…”

Unmanned aerial vehicle control costs mirror bird behaviour when soaring close to buildings

“…This model was used to locate suitable areas of lift, which were then tested in flight trials. 23 Birds fly in the same conditions as SUAVs and face similar challenges in energy management and flight control. Birds frequently reduce their energy expenditure by exploiting environmental wind fields such as tailwinds, wind gradients and updraughts.…”