Technical Research On Multi-degree-of-freedom Piezoelectric Actuators For Ballistic Correction

Precision strike ammunition has become an important research direction of modem weapons and equipment.Trajectory correction projectile,which significantly improves the shooting accuracy at a lower cost,has become the current research focus.Warhead-deflection trajectory correction features higher control efficiency and aerodynamic characteristics.However,the current warhead deflecting mechanism still has some problems to be solved:small warhead deflection angle,loose structure,complex control method and it is easy to be affected by electromagnetic interference.The multi-degree-of-freedom piezoelectric actuator not only has the advantages of compact structure,large output torque and immunition of electromagnetic interference,but also can realize the deflecting and rotating motion needed for the head deflection trajectory correction simultaneously.Therefore,it is used as a good actuator for warhead deflection mechanism.Based on the current multi-degree-of-freedom piezoelectric actuators,the author presents a new type of piezoelectric actuator which is more suitable for warhead deflection mechanism.And the structure and optimization design,deflection control analysis,finite element modeling,drive circuit design and other researches have been implemented in this paper.The main research contents are summarized as follows:(1)Combining the application background of the warhead deflection mechanism and the characteristics of the multi-degree of freedom piezoelectric actuator,three kinds of multi-degree-of-freedom piezoelectric actuators are designed.After comparison and analysis,the stator-built-in structure has better output performance and enjoys a more compact structure.Therefore,the stator built-in structure is chosen as the research object.(2)The working principle of multi-degree-of-freedom piezoelectric actuator with stato-built-in structure are elaborated.And the actuator drive deflection of warhead with only four driving signals are analyzed.Three kinds of deflection control methods are proposed,and the relationship between selection of controllling methods and deviated target angles is summarized.(3)In order to improve the output performance and conversion efficiency of the new actuator,the velocity factor of the piezoelectric actuator and the the ratio of the normal amplitude to the tangential amplitude of the stator particle is taken as the optimization target.After optimization,the velocity factor is increased by 14.89%,and the amplitude ratio is increased by 17.10%.The principle prototype is processed with the optimized structure.(4)In order to predict the output performance of this new type of actuator,a three-dimensional theory contact model of the stator and rotor is established,and the finite element methods is used to validate that the three-dimensional theory contact model is more accurate than the traditional two-dimensional theory contact model.The output performance of the piezoelectric actuator during the process of deflection and rotation are calculated,verify its ability to meet the needs of trajectory correction.(5)The AD9959 driver circuit is designed for the miniaturization of the warhead deflection mechanism with the consideration to get an adjustable and uniform four output signals and reach a certain power requirements.The design process applys the multi-channel integrated chip as much as possible.To meet the design requirements,the driving voltage is high and the driving signal is stable and convenient to adjust.