Abstract:

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 π/2, leading to that two phase in-plane bending vibration modes with a spatial phase difference of π/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.

Key words: dynamical characteristics, tracked mobile system, transient characteristics, piezoelectric actuator