Research interests
What the MAV Group does
MAVs are “a class of unmanned aerial vehicles (UAV) that has a size restriction and may be autonomous. Modern craft can be as small as 15 centimetres. Development is driven by commercial, research, government, and military purposes; with insect-sized aircraft reportedly expected in the future. The small craft allows remote observation of hazardous environments inaccessible to ground vehicles. MAVs have been built for hobby purposes, such as aerial robotics contests and aerial photography."
My interest in micro planes has resulted in a research group in the MAV Group which we started in 2001, by producing one of the lightest airframe (7.3g) membrane-structure micro air vehicles in the world at that time. In the last few years we have been awarded 8 grants by the USAF for work on understanding the dynamic response of fixed, rotary and flapping wing MAVs in turbulent flow, including 5 Window on Science travel grants to give invited talks at US and European meetings. Most research is now focussed on understanding MAVs and the influence of both their design type (e.g. fixed wing vs flapping vs rotary) and how these differing designs cope with the effects of atmospheric turbulence. I supervise several PhD students in this area.
We have been focusing on how MAVs will cope with the turbulence inherent in the Atmospheric Boundary Layer (ABL) in order to make MAVs more useful. Our previous work documented the temporal and spatial environment of flight through turbulence inherent in the ABL, as would be perceived by MAVs, both manmade and natural (e.g. small birds, insects). This has involved working with the instrumented eagle of the Oxford Animal Flight Group where we took multi-point measurements of turbulence whilst the instrumented eagle was soaring and high-speed videoing on locusts flying in smooth and turbulent flow in our wind tunnels.
We have replicated this turbulent environment in several wind tunnels, including the largest wind tunnel in the Southern Hemisphere and shown that aspects of the naturally turbulent flow environment had been reproduced with good accuracy.
Flying experiments
We have flown instrumented fixed-wing, rotary-wing and flapping-wing MAVs in the tunnel, including some aerobatics (and many crashes!). Pilot inputs and aircraft accelerations were recorded on the MAVs. For some tests, synchronised measurements of the approach flow time history (u,v,w sampled at 1250 Hz) at four laterally disposed locations were made and retro-reflective markers and six video cameras permitted video tracking. The piloting aim was to hold straight and level flight in the 12m wide x 4m high x ~50m long test section whilst flying in a range of turbulent wind conditions. The results showed that the rotary craft were less sensitive to the effects of turbulence compared to the fixed-wing craft. It was found that whilst fixed-wing aircraft were relatively easy to fly in smooth air, they became extremely difficult to fly under high turbulence conditions. Rotary craft, whilst somewhat more difficult to fly per se, did not become significantly harder to fly in relatively high turbulence levels.