Agility Comparison of Stabilizer and Direct Head Systems Mounted on an Unmanned Agricultural Helicopter

Abstract

Abstract. Recently, there has been increasing interest in using unmanned aerial vehicles (UAVs) to reduce the labor required for pest control and to protect farmers from exposure to pesticides. Unmanned aerial application has become a new paradigm in pesticide application; however, a uniform speed must be maintained within a short accelerating distance when spraying small plots, and this depends on the skill of the operator, which is difficult to rely on. In this study, the agility of a direct head system mounted on an unmanned agricultural helicopter was compared with that of a conventional stabilizer head system by using a pitch sweep test in CIFER, a dynamic analysis software program. The controllable frequency range of the unmanned agricultural helicopter with the direct head was analyzed to range between 0.06 and 5 Hz, and the responsiveness of the helicopter with the conventional stabilizer head was observed in a relatively low frequency range of 0.06 to 1.6 Hz. In addition, in comparing the equivalent time delay between the representative transfer functions from the pitch direction input to the surge acceleration obtained using NAVFIT analysis, the time delay of the direct head was shorter than that of the stabilizer head, although the extent of the enhancement was not satisfactory because of the tail gyroscope used for intrinsic attitude stability. Keywords: Agility, Agricultural unmanned helicopter, CIFER, Flight dynamics, Swash head system.