Study On Ultrasonic Motor For Spin-stabilized Guied Ammunition

As a novel class of actuators,owing to the specific characteristics such as small size,light weight,high motion accuracy,no interference with the magnetic field,and simple and compact structure,the traveling wave type rotary ultrasonic motor(TRUM)has certain advantages in the drive and execution system of the spin-stabilized guided ammunition.The application of the TRUM can greatly simplify the structure of the rudder-actuator,optimize its operation accuracy and response speed,and improve its core competitiveness.However,the TRUM is sensitive to the working environment,especially in the application of the spin-stabilized guided ammunition,the dynamic performance of the TRUM will be affected by the centrifugal field,even the control accuracy of the whole guidance system.In this dissertation,the study on the TRUM for spin-stabilized guided ammunition is carried out.Based on the basic structure and working principle of the TRUM,the influence of the strong centrifugal field on the dynamic characteristics of the stator is studing,and the changing trend of the mechanical properties of the TRUM in the centrifugal field is analyzed.The rudder technology used in the spinstabilized guided ammunition is studied including the theoretical modeling of the TRUM in the centrifugal field,the innovative design of the speed control mechanism of the canard,and the experimental demonstration.The main contributions of this dissertation can be summarized as follows:1.The concepts,characteristics and research progress of the TRUM and the guided ammunition are introduced respectively.The technical problems faced in the design of the rudder-actuator in spinstabilized guided ammunition are summarized,and the key technical problems in the application of the TRUM in spin-stabilized guided ammunition are summarized.2.Based on Hamilton principle,the dynamic equation of the stator of the TRUM in centrifugal field is established by semi-analytical method and finite element method.The influence of centrifugal stiffness on the dynamic characteristics of the stator is expounded,and the additional stiffness matrix of centrifugal is derived.Finally,it is proposed that the natural frequency of the stator in the centrifugal field can be determined by the voltage amplitude of the feedback in the soliton region of the piezoelectric ceramics.3.The warping deflection of the stator of the TRUM in the centrifugal field is analyzed,and the influence of the deflection on the contact between the stator and the rotor of the TRUM is studied.Then,the output model of the TRUM is established,and the mechanical load characteristics of the TRUM in the centrifugal field are measured by experiments.It is found that the output performance of the TRUM decreases with the increase of the centrifugal speed.Finally,an optimization method for the output performance of the TRUM in the centrifugal field is proposed.4.Based on the working principle and characteristics of the rudder actuator of the spin-stabilized guided ammunition,the speed regulation method of friction brake system driving by the TRUM is put forward.The friction brake model between the brake head and the rotating disc is established.Considering the mechanical load characteristics of the TRUM,the frictional torque produced by the brake head on the rotating disc(canards)is calculated,the rotating speed output equation of the rotating disc is obtained,and the influence of various parameters in the system on brake performance is analyzed.The validity of the model is verified by experiments.Finally,experiments results show that the maximum brake stroke of the brake head is 0.25 mm,the maximum rotation angle of the TRUM is 35 degrees,and the maximum frictional torque of the brake head is 0.35 Nm.5.The friction brake test system is improved.The minimum holding time of the rotating disc rapidly dropping from 1000 rpm to 0 rpm is about 150 ms,and the fluctuation rate of the rotating disc speed can be maintained below 10%.The application of the system in the rudder-actuator is studied.The influence of centrifugal speed on the friction braking speed regulation model of the rudder-actuator is analyzed,and a ground simulation test platform of rudder-actuator is built.The results show that the minimum holding time of the rudder wing(the speed of the canard relative to the inertial coordinate system)is about 180 ms,and the velocity fluctuation rate is about 10%.6.Aiming at the problems of large fluctuation of rotational speed of the rotating disc and long response time caused by transmission clearance in frictional brake speed regulation system,a microstructure is deigned in the brake head,and macro-micro combination friction braking speed regulation method with the TRUM in series are proposed.Based on the triangular amplification principle,a microdisplacement amplification mechanism with laminated piezoelectric ceramics is designed.The mechanical output characteristics of the mechanism are studied by simulation and experiment.The maximum output displacement can reach 55 μm,the maximum output force is 44.1 N(the peak-peak driving voltage is 150 V).A macro-micro speed regulation system composed of the TRUM and microstructure in series is built and tested.