Unmanned Rotorcraft In Aggressive Environment: Aerodynamic Flow Performance Against Wind Gust

Unmanned rotary-wing aircrafts or rotorcrafts are often prone to diverse atmospheric turbulences, and undeniably, abrupt gusts are reckoned to be the most acquainted commotion of them. Time and again, gust turbulence have dictated being the regulating trigger for countless mishaps concerning micro aerial vehicles. Given that the core/main rotor provides principal lift along with governing directional control and dynamic stability for any rotorcraft, the demeanors of thrust or induced air-flow through the gyrating blades largely signify the barebones of its functionality. This paper presents an idiosyncratic approach towards reviewing the impact of wind gust on rotor induced aerodynamic flow performance of an unmanned rotorcraft. Artificial gusts have been generated through the inherent concept of forced pitched oscillation without the use of any conventional wind tunnel. Gust air-speed and the rotor induced air-speed are gauged through the same contraption to provide homogeneous quantitative valuation. Each rotor-halves have been assessed `root-to-tip' across designated span-wise positions against selected strengths of gust. Comparative analysis with normal atmospheric condition indicated gradual loss of cumulative thrust during hover (15-40%) and forward flight (10-30%) within the stipulated gust range and infers the risk of declining altitude. Protuberant imbalance of thrust across the rotor disk during hover indicated the likelihood of lackadaisical half-pitched rolling motion. However, during forward flight, the reduced discrepancy of thrust between the rotor halves signified gradual loss of cruising speed with regards to the increasing gust strength for the specific rotorcraft model. Experimental findings in this study exhibited prospect of appraisal with full-scale rotorcrafts

Flight validation of a feedforward gust-attenuation controller for an autonomous helicopter

This paper presents a practical scheme to control heave motion for hover and automatic landing of a Rotary-wing Unmanned Aerial Vehicle (RUAV) in the presence of strong horizontal gusts. A heave motion model is constructed for the purpose of capturing dynamic variations of thrust due to horizontal gusts. Through construction of an effective gust estimator, a feedback-feedforward controller is developed which uses available measurements from onboard sensors. The proposed controller dynamically and synchronously compensates for aerodynamic variations of heave motion, enhancing disturbance-attenuation capability of the RUAV. Simulation results justify the reliability and efficiency of the suggested gust estimator. Moreover, flight tests conducted on our Eagle helicopter verify suitability of the proposed control strategy for small RUAVs operating in a gusty environment