Fundamentals of piezoceramic actuation for micrometer and submicrometer motions for the NanoWalker robot

Abstract

The NanoWalker project aims at developing a new type of miniature wireless autonomous robot capable of performing tasks at the molecular and atomic scales. To do so, the robot must be capable to position itself within the maximum range of the embedded instrument by using a new type of relatively fast locomotion system capable of sub-micrometer step sizes. To prevent excessive traveling delays due to the critical requirement of small step sizes, relatively fast motions have been achieved through several thousand steps executed per second and operation at resonance frequency. Furthermore, step sizes larger than the maximum bending amplitude of the piezo-legs have been achieved with jumps initiated by extremely fast onboard computer controlled angular accelerations of the legs form known parameters such as mass, moment of inertia, and coefficient of friction, just to name a few. This locomotion system is based on three piezo-actuated legs formed as a pyramid with the apex pointing upward. Although this structure is relatively simple, its kinematic behavior becomes extremely sensitive to many variables that must be well understood. Such understanding is critical for the embedded computer system responsible for controlling the three legs. In this paper, an introduction with the fundamental principles behind this new actuation system is presented.