A micro air vehicle (MAV) is a semiautonomous airborne vehicle which measures lessthan 15 cm in any dimension. It can be used to access situations too dangerous for directhuman intervention, e.g., explosive devices planted in buildings and videoreconnaissance and surveillance, etc. As demonstrated by flying birds and insects,flapping flight is advantageous for its superior manoeuvrability and much moreaerodynamically efficient at small size than the conventional steady-state aerodynamics.Piezoelectric actuators are easy to control, have high power density and can producehigh output force but usually the displacement is small. With appropriate strokeamplification mechanisms piezoelectric actuators can be used to drive the flappingwings of MAV.This research aims to develop a piezoelectric fan system with 2 degrees of freedom ofmotion for flapping wing MAV applications. In this project, piezoelectric fansconsisting of a piezoelectric layer and an elastic metal layer were prepared by epoxybonding. A flexible wing formed by carbon fibre reinforced plastic wing spars andpolymer skin was attached to two separate piezoelectric fans to make them coupled.Two sinusoidal voltages signals of different phase were then used to drive the coupledpiezoelectric fans. High speed camera photography was used to characterize the twodegrees of freedom motion of the wing. Theoretical equations were derived to analysethe performance of the piezoelectric fans in both quasi-static and dynamic operations,and the calculated results agreed well with the finite element analysis (FEA) modellingresults. It has been observed that the phase delay between the driving voltages appliedto the coupled piezoelectric fans plays an important role in the control of the flapping vand twisting motions of the wing. Selected factors such as the gap between the twopiezoelectric fans which can affect the performances of the wing have been investigatedand the experimental results were compared with the FEA modelling results.
展开▼
