| Agricultural unmanned helicopter plays an increasingly important role in the modernization ofagriculture. It’s necessary to resolve the contradiction between stability and handling qualities ofhelicopters under urgent market requirement. Base on a small-scale agricultural unmanned helicopter,the flight control system is developed by the research on object modeling, functions of flight modesdesigning, the joystick control technologies and internal and external loop control law designing.The small-scale agricultural unmanned helicopter is close to a model helicopter. However, themain rotor and the stablizer bar are highly coupled, it takes a longer period to acquire the dynamicmodel with traditional analytic modeling methods. Therefore CIFER tool based on frequencyidentification method is taken to quickly establish the transfer function in hover state. According tothe needs of the pesticide spraying, semi-autonomous control mode of the joystick is designed, as wellas several flight modes and functions for unmanned helicopters. The advantages and disadvantages ofdifferent joystick control modes are token into comparison, and finally two joystick agriculturalcontrol schemes are proposed for different manipulation level of persons. Because of the stablizer bar,the longitudinal and lateral channels of helicopter reflect the short-period lightly damped mode. Tosolve this problem, three schemes are presented, namely routine control, routine control with notchfilter and angular rate integrating structure. With these schemes, velocity control strategy is developed.According to the flight demand, regular position control law is designed. Furthermore, controlschemes are put forward to ensure flight safety of the helicopter.The simulation and fly results show that the model that acquired by CIFER performances well.The strategy of angular rate integrating structure has good control effect. The joystick control modecan improve handling qualities and satisfy the demands of flight. |
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