Modelling and Simulation of a Flapping Wing Mechanism Driven by a Brushless Servo Motor

Flapping wing mechanism is designed to generate flapping motion for a micro air vehicle. Some issues concerning with the design and control of flapping wing mechanism are discussed in this paper. Firstly the problem of phase-lag between two wings is treated. To eliminate phase-lag, a method of modifying the design is proposed. Then, motion controlling of a flapping wing mechanism by means of changing the voltage inputted to servo motor is studied. Based on Lagrange’s formulation and Kirchhoff’s voltage law, motion equation for a servo motor coupled to flapping wing mechanism is established. Fourth-order Runge-Kutta method is employed to integrate this equation. For the purpose of finding the relationship between the flapping motion and the input voltage, a response diagram obtained from simulation of the system is utilized. A crucial voltage V_C is obvious in the response diagram. If the input voltage is lower than V_C, the mechanism will settle at its fixed point, only when the input voltage is higher than V_C, can the mechanism work in order. Both to find all fixed points and to analyze their stability for a complex nonlinear dynamic system are difficult tasks. A numerical method to deal with these difficulties is proposed. The results of simulation also show that the flapping frequency increases with the increasing of input voltage provided that the input voltage is higher than V_C.