中文摘要：

提出一种夹心式压电作动器,用于直接驱动履带以构成小型履带式行星探测移动系统。压电作动器由变截面夹心式压电振子以及对称设置在其两端的两个圆环部分组成。压电作动器在两相具有π/2相位差的电信号驱动下激励出两相正交工作模态并在圆环处呈现两相在空间上具有π/2相位差的面内弯曲振动,耦合形成沿圆环周向旋转的行波,圆环表面质点做微幅椭圆运动,经摩擦作用驱动履带运动。利用有限元法对压电作动器进行了结构设计和动力学特性分析,并通过测振试验进行验证：1模态试验结果表明压电作动器的两相试验工作模态频率差为16 Hz,满足行波在圆环部分形成的要求;2通过谐响应试验得到了圆环表面质点在一个周期内的椭圆运动轨迹,与仿真结果相吻合。构建压电作动器驱动的可进行双向运动的履带移动系统,瞬态特性试验结果表明：1履带移动系统具有快速响应特性;2履带移动系统的瞬时运动速度呈周期性变化。

英文摘要：

A sandwich-type piezoelectric actuator with variable cross-section structure is proposed, being able to drive track and construct a tracked mobile system featuring the potential application on planetary exploration. The piezoelectric actuator is composed of a sandwich-type variable cross-section piezoelectric vibrator and two annular parts that symmetrically place at the both ends of the piezoelectric vibrator. Two phase orthogonal operating modes are stimulated in the piezoelectric actuator under two phase exciting voltages with a phase difference of ~/2, leading to that two phase in-plane bending vibration modes with a spatial phase difference of n/2 are presented in the annular parts. Therefore, rotating traveling waves along the circumferences of the annular parts are generated, and surface particles of the annular parts are moved in elliptical trajectories and then the track is driven by friction force. The structure design and dynamical characteristics of the piezoelectric actuator are conducted utilizing the finite element method, and results are verified by vibration measurement experiments. Modal experiments indicate that the frequency difference between two phase operating modes is 16 Hz, meeting the formation requirement of traveling waves in the annular parts. The elliptical motion trajectories of the annular surface particles obtained by harmonic response tests are consistent with the simulation results. A tracked mobile system with bidirectional movement driven by the piezoelectric actuator is structured and its transient characteristics are experimentally investigated. Results show that the tracked mobile system featured fast response and its transient velocity varied periodically.