Enclosing the rotor in a shroud can improve the power loading of the vehicle and rotor protection. However shrouded rotor vehicles are inherently unstable platforms. This paper presents design, flight testing and PID control implementation of a shrouded rotor vehicle. Studies on the differences in stability between a shrouded and unshrouded rotor were conducted with a teetering and a hingeless rotor. The shroud directly affects the center of lift of the MAV which in turn impacts the flight stability of the vehicle. At MAV scales, due to the relatively low inertia to mass ratios, sensitivity to asymmetric flow field over the shroud is increased. Effects of asymmetric tip clearance and vatiations in rotor tip path plane relative to the shroud axis on flight stability of the vehicle were qualitatively studied. A closed loop PID flight controller was developed and tested to mitigate unstable oscillations in flight.
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