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.
Non-dominated sorting genetic algorithm II(NSGA-II)with multiple constraints handling is employed for multi-objective optimization of the topological structure of telescope skin,in which a bit-matrix is used as the representation of a chromosome,and genetic algorithm(GA)operators are introduced based on the matrix.Objectives including mass,in-plane performance,and out-of-plane load-bearing ability of the individuals are obtained by fnite element analysis(FEA)using ANSYS,and the matrix-based optimization algorithm is realized in MATLAB by handling multiple constraints such as structural connectivity and in-plane strain requirements.Feasible confgurations of the support structure are achieved.The results confrm that the matrix-based NSGA-II with multiple constraints handling provides an effective method for two-dimensional multi-objective topology optimization.
Liu WeidongZhu HuaWang YipingZhou ShengqiangBai YaleiZhao Chunsheng
A novel 0-Poisson's ratio cosine honeycomb support structure of flexible skin is proposed. Mechanical model of the structure is analyzed with the energy method, finite element method (FEM) and experiments have been performed to validate the theoretical model. The in-plane characteristics of the cosine honeycomb are compared with accordion honeycomb through analytical models and experiments. Finally, the application of the cosine honeycomb on a variable camber wing is studied. Studies show that mechanical model agrees well with results of FEM and experiments. The transverse non-dimensional elastic modulus of the cosine honeycomb increases (decreases) when the wavelength or the wall width increases (decreases), or when the amplitude decreases (increases). Compared with accordion honeycomb, the transverse non-dimensional elastic modulus of the cosine honeycomb is smaller, which means the driving force is smaller and the power consumption is less during deformation. In addition, the cosine honeycomb can satisfy the deform- ing requirements of the variable camber wing.
Liu WeidongZhu HuaZhou ShengqiangBai YaleiWang YuanZhao Chunsheng
