A novel variable camber wing driven by ultrasonic motors is proposed.Key techniques of distributed layout of drive mechanisms,coordination control of distributed ultrasonic motors as well as novel flexible skin undergoing one-dimensional morphing are studied.The system integration of small variable camber wing is achieved.Distributed layout of parallelogram linkages driven by geared ultrasonic motors is adopted for morphing,aimed at reducing the load for each motor and producing various aerodynamic configurations suitable for different flying states.Programmable system-on-chip(PSoC)is used to realize the coordination control of the distributed ultrasonic motors.All the morphing driving systems are assembled in the interior of the wing.The wing surface is covered with a novel smooth flexible skin in order to maintain wing shape and decrease the aerodynamic drag during morphing.Wind tunnel test shows that the variable camber wing can realize morphing under low speed flight condition.Lift and drag characteristics and aerodynamic efficiency of the wing are improved.Appropriate configurations can be selected to satisfy aerodynamic requirements of different flight conditions.The study provides a practical application of piezoelectric precision driving technology in flow control.
A method based on programmable system-on-chip(PSoC)is proposed to realize high resolution stepping motion control of liner displacement mechanism driven by traveling wave rotary ultrasonic motors(TRUM).Intelligent controller of stepping ultrasonic motor consists of PSoC microprocessor.Continuous square wave signal is sent out by the pulse width modulator(PWM)module inside PSoC,and converted into sinusoidal signal which is essential to the motor′s normal working by power amplifier circuit.Subsequently,signal impulse transmission is realized by the counter control break,and the stepping motion of linear displacement mechanism based on TRUM is achieved.Running status of the ultrasonic motor is controlled by an upper computer.Control command is sent to PSoC through serial communication circuit of RS-232.Relative program and control interface are written in LabView.Finally the mechanism is tested by XL-80 laser interferometer.Test results show that the mechanism can provide a stable motion and a fixed step pitch with the displacement resolution of 6nm.
