INVESTINGATION DOWNWARD WIND PRESSURE ON A SMALL QUADROTOR HELICOPTER

Abstract

Abstract. Small rotary-wing UAVs are susceptible to gusts and other environmental disturbances that affect inflow at their rotors. Inflow variations cause unexpected aerodynamic forces through changes in thrust conditions and unmodeled blade-flapping dynamics. This pa­per introduces an onboard, pressure-based flow measurement system developed for a small quadrotor helicopter. The probe-based instrumentation package provides spatially dis­tributed airspeed measurements along each of the aircraft-fixed axes. Lateral and vertical windspeed estimates enable the development of disturbance-tolerant flight control strate­gies. The focus of this paper is vertical flow disturbances such as those caused by the downwash of a second vehicle. Real-time velocity measurements are incorporated into a recursive Bayesian estimator to localize a nearby rotorcraft using its downwash. A path planner developed for proximity flight is demonstrated through indoor flight testing with multiple vehicles to safely guide an instrumented quadrotor towards a goal point while avoiding another quadrotor.