Research On The Four Rotor Frame Piezoelectric Actuator

The miniaturization of drones is of great significance for environmental monitoring,disaster relief,counter-terrorism and military fields.The four-rotor unmanned aerial vehicle has a simple structure,but there are still many challenges in order to be practical in the process of miniaturization.These include flight stability problems with reduced size and mass and multivariable,nonlinear and strong coupling problems with autonomous flight control,while power sources are the biggest obstacle to miniaturization.At present,electromagnetic motors are widely used,and the electromechanical conversion efficiency drops sharply after being reduced to a millimeter size,and the endurance capability is insufficient.Considering that the piezoelectric drive has high power density,fast response,convenient control,simple and compact structure,and easy miniaturization,it can maintain high efficiency at a millimeter scale,especially the unique value of electromagnetic radiation and electromagnetic interference resistance in military applications,a new method of micro-miniature four-rotor piezoelectric drive is proposed by constructing reed and frame piezoelectric actuators using inverse piezoelectric effect and friction.Eight reeds are pressed through the eccentric groove cylindrical ring to the outer surface of the stator,and rotate under the rotation of the stator to form a single-rotor reed type piezoelectric actuator.The stator working mode is a second-order bending vibration,which is convenient for clamping and driving.The prototype experiment shows that when the driving voltage exceeds 325 Vpp,the speed is 1947.3 r/min,the torque is 1.32 mN·m,and the rotor with a radius of 30 mm is installed with a lift of only 0.06 g.The four rings are connected by a variable-section piezoelectric composite beam to form a square frame fuselage.The rotary motion of the four rings is excited by the connecting beam,and the rotor is driven by the conical rotor to form a four-rotor aircraft with integrated structural functions.The principle prototype has a driving force of 350 Vpp,a rotational speed of 2000 r/min,and a mounting diameter of 35 mm rotor to generate a lift of 0.6 g.After structural optimization and miniaturization design,the weight is reduced by 82.6%(5.8 g)and the length is reduced by 48.9%(74.6 mm).When the driving voltage is 350 Vpp,the speed is increased by 140%(4800 r/min)and the torque is 7.5 mN/ m,the lift is 1.6 g.After using lightweight materials and further optimization,it is expected to achieve flight.