This study carries out the transient flight control simulation of a Flapping-Wing Micro Air Vehicle using Extended Unsteady Vortex-Lattice Method. This method uses the panel method and unsteady vortex-lattice (UVLM) method including the leading-edge suction analogy for leading-edge vortices (LEVs) effect and the vortex-core growth model for the effect of eddy viscosity in the vortex wake. This method has advantages in that it requires relatively less computational cost compared to CFD and provides more precise aerodynamic forces and moments than the conventional quasi-steady aerodynamic model. Based on the multibody dynamic analysis with the aerodynamic model, gainscheduling LQR controller is designed for non-linear system to track reference input.
In this study, the use of the twisted string concept with a pin, serving as a moment arm, is proposed to produce the snapthrough of a pre-compressed beam so that the whole system can be used as an effective on/off actuator. The twisted string mechanism is to produce a horizontal pulling force to the pin, which triggers the snap-through of the beam. The actuation moment required to trigger the bistable beam in this study is 24.3 Nmm, corresponding to a horizontal force of 0.81 N. The twisted string actuator is able to produce a pulling force of 1 N, which is further pulled through a distance of 5-mm. Static performance of the integrated system based on the effects of the length of the string on the required input motor voltage, torque, and the overall system response time is experimentally investigated. The snap-through sequence during the static experiment is also captured with a high-speed camera. The input voltage to the motor increases as the length of the string is increased. The length of the string also affects the overall system response, motor speed and torque. The whole snap-through of the beam happens within 100 msec after the trigger signal is sent.